transition metal mediated, stereoselective higher …figure 13.1.3 crystal structures of diene,...
TRANSCRIPT
TRANSITION METAL MEDIATED, STEREOSELECTIVE
HIGHER-ORDER [6+4] AND DIELS-ALDER [4+2] CYCLOADDITION REACTIONS:
SYNTHESIS OF NOVEL 2-SILYL SUBSTITUTED-1,3-DIENYL COMPOUNDS
AND THEIR DOMINO REACTIONS
BY
RAMAKRISHNA R. PIDAPARTHI
A Dissertation Submitted to the Graduate Faculty of
WAKE FOREST UNIVERSITY GRADUATE SCHOOL OF ARTS & SCIENCES
in Partial Fulfillment of the Requirements
for the Degree of
DOCTOR OF PHILOSOPHY
Chemistry
August 2011
Winston-Salem, North Carolina
Approved by:
Mark E. Welker, Ph. D., Advisor
Gloria K. Muday, Ph. D., Chair
Ulrich Bierbach, Ph. D.
Christa L. Colyer, Ph. D.
Paul B. Jones, Ph. D.
II
Dedication
I dedicate this work to the three most precious people in my life:
To my wife, Atchamamba (Aruna) Yarram for her great love, support and patience, words
cannot express.
To my parents: In loving memory of my father Subba Reddy Pidaparthi, without his
encouragement in my earlier years, I would have never turned out to be what I am today. Dad, I
am always fond of your memories of you as role model for family values, love and support.
My beloved mother, Subbayamma Pidaparthi even staying oceans away for these many years
always been optimistic, encouraging. I feel energetically motivated towards destiny every time I
spoke to you.
To the three, I will be eternally grateful for the role each of you has played in turning me what I
am today. You are part of this accomplishment and I thank you for your love and support.
III
Acknowledgments
I would like to first express my gratitude to Dr. Mark E. Welker for his wonderful guidance
and support all these many years. I am very grateful for the opportunity you gave me to work in
your labs. I am very fond for being acquainted with you in learning good laboratory professional
and personnel skills. His direction and guidance has not stopped with only problem solving but
also helped me in widening my thinking horizons on how to relate the solutions to others. I
would also like to thank the members of my committee, Dr. Ulrich Bierbach and Dr. Paul B.
Jones for their review and in-puts through out my research work. Also, I greatly appreciate Dr.
Gloria K. Muday and Dr. Christa L. Colyer help in filling the graduate chair and committee with
such a short notice. In addition, I would like to extend my thanks to Dr. Al Rives for helping me
to effectively use the electronic resources in completing my research project.
I would like to extend my appreciation to the faculty and staff of the chemistry department
at Wake Forest University for the given educational opportunity and resources. In particular, I
would like to thanks to each and every individual faculty who taught me chemistry in possible
easy way to understand and keep memorize. My special thanks to Dr. Marcus W. Wright and Dr.
Cynthia C. Day for their extended help not only solving the spectral issues but also their
motivation, and dedication in shaping my research in better possible way. I would like to
acknowledge the chemistry department for their competitive financial support and special
thanks to Kent R. Greer, assistant director for international students and scholars for the role he
played in my admission and help in dealing with immigration related issues for international
students.
IV
I extend my special thanks to the members of the Welkers group, past and present members.
I learned a lot from all of you and I thank for the advice and friendship. I specially thank to Dr.
Marian A. Franks, Dr. Harinath Chakrapani, Dr. Mike J. Gorczynski, Dr. Rajkumar
Guddneppanavar, Subhasis De, Hemanta Baruah, Jayati for their positive attitude, times of
laughter shared and friendship that went beyond the lab.
I would like to express my thanks to Dr. Ivy F. Carroll for his guidance and encouragement to
accomplish my post-doctoral experience. I greatly appreciate for all of his advices, cordial
relationship and mentorship.
I also want to express my deep appreciation for the love and support of my family. In
particular, to my sisters, Koteswari, Seetharavamma, Rajyalakshmi and Vijayalakshmi and elder
brother Jaya vidya sagar, I am grateful for all of their love and affection towards me as a younger
brother. I always remember the warmth of your blessings in spite of the distance you have
always been there. And to my brother-in-laws: Anji Reddy, Koti Reddy, Souri Reddy and Subba
Reddy, I thank you all for your words of encouragement. I cannot express my thanks in words to
my wife, Aruna, for the sacrifices you have made. I am eternally grateful for the love and
support you gave me in being half part of my life. Thank you dear for your love.
V
Table of Contents
DEDICATION II
ACKNOWLEDGMENTS III
LIST OF TABLES VIII
LIST OF FIGURES IX
LIST OF SCHEMES X
LIST OF ABBREVATIONS XVI
ABSTRACT XIX
CHAPTER 1:
Introduction: Overview of Traditional Diels-Alder Reactions 1
1) Mechanistic Aspects 2
2) Stereochemical Aspects
2.1) Regioselectivity 4
2.2) Diastereoselectivity 7
2.3) Enantioselectivity 11
CHAPTER 2:
TRANSITION METAL MEDIATED, STEREO-SELECTIVE HIGHER-ORDER [6+4]
AND DIELS-ALDER [4+2] CYCLOADDITION REACTIONS
3) Introduction 13
4) Higher-Order Cycloaddition Reactions using 6π and 4π Components
4.1) Metal-free Tropones in Higher-Order Cycloaddition Reactions 14
4.2) Metal-mediated Tropones in Higher-Order Cycloaddition Reactions 19
5) Results and Discussion 24
6) Conclusion 33
7) Experimental 34
VI
CHAPTER 3:
SYNTHESIS OF NOVEL 2-SILYL SUBSTITUTED-1,3-DIENYL COMPOUNDS
AND THEIR DOMINO REACTIONS
8) Introduction 49
9) Literature Review on Synthesis & Cycloaddition Reactions Of Silylated
(Conjugated) Dienes
9.1) Synthesis of Silyl Dienes & Cycloadditions (organic approach) 50
9.2) Transition-Metal Mediated Silyl Diene Synthesis & Cycloadditions 54
10) Literature Review on Cross-Coupling Reactions 62
10.1) Fluoride-Assisted Cross-Coupling Reactions of Silanes
10.1.1) Cross-Coupling Reactions of Vinyl Silanes 63
10.1.2) Cross-Coupling Reactions of Aryl Silanes 69
10.2) Non-Fluoride Mediated Cross-Coupling Reactions of Silanes 72
11) A Brief outlook on:
11.1) Tandem Reactions 74
11.2) Domino Reactions 75
11.3) Alkoxy Conjugated Silyl Dienes – Literature Precedence 75
12) Aim and Scope of the Present Study 77
13) Results and Discussion 81
14) Future Research 97
15) Conclusion 105
16) Experimental 106
CHAPTER 4:
17) Conclusion 140
Bibliography 142
Appendix – A: Crystallographic data for [6+4] cycloadduct, 5.2.2b 154
Appendix – B: Crystallographic data for [4+2] cycloadduct, 5.2.3b 166
Appendix – C: NMR spectral data for silyl dienes, 11.3.2b, 13.1.2a-c 186
VII
Appendix – D: Crystallographic data for 13.1.2a 194
Appendix – E: Crystallographic data for 13.1.2c 214
Appendix – F: Crystallographic data for 13.1.2d 232
Appendix – G: NMR kinetic study of dienes, 13.1.2a, 13.1.2d & 11.3.2b 251
Appendix – H: Graphical representation of NOE data of 13.1.3a, b & 13.1.4a, b 257
Appendix – I: Crystallographic data for 13.1.3a & 13.1.3b 259
Appendix – J: HMBC NMR spectra of cycloadduct, 13.1.4c 271
Appendix – K: Structural conformation of 13.2.8b & 13.2.9 by 2D NMR Spectroscopy 273
Appendix – L: Crystallographic data for cross-coupled cycloadduct, 13.3.2e 278
Scholastic Vita 292
Biography 295
VIII
List of Tables
Table 5.3.1 Cycloaddition reactions of unsubstituted tropones at bond
forming centers (C2 and C7) 30
Table 5.3.2 Cycloaddition reactions of highly substituted tropones 31
Table 13.1.2 Comparative reactivity studies of silylbuta-1, 3-dienes 88
IX
List of Figures
Figure 1.0.1 Diels-Alder reaction with formation of “FOUR” stereocenters 1
Figure 1.0.2 Conformational changes of diene at reaction conditions 2
Figure 1.0.3 Transition-Metal role in attaining “ciscoid” conformation 2
Figure 1.0.4 Relative rate of reactivity (Krel) of few “ciscoid” dienes in
Diels-Alder reactions 2
Figure 1.0.5 FMO Diagrams for normal (A) and inverse (B) electron demand
Diels-Alder reactions 3
Figure 1.0.6 Classification of Diels-Alder reactions based on FMO analysis 3
Figure 2.2.1 Stereochemical considerations (Alder’s endo rule) 8
Figure 2.2.2 Maximum overlap of orbitals enhance the “endo” selectivity 8
Figure 4.1.1 Catalytic reaction pathway of chromium (0)-catalyzed
higher-order cycloaddition reactions 21
Figure 5.2.1 Crystal Structure of [6+4] Cycloadduct, 5.2.2b 26
Figure 5.2.2 Exo approach of tropone to a cobalt substituted diene 27
Figure 5.2.3 Schematic representation of NOE data for [6+4] cycloadduct,
5.2.2e 29
Figure 5.3.1 Crystal Structure of [4+2] Cycloadduct, 5.2.3b 32
Figure 10.1.1 Resonance structures of arylsilatrane 71
Figure 13.1.2 Crystal Structures of [buta-1, 3-dien-2-yl]silatrane, 13.1.2a 84
Figure 13.1.3 Crystal Structures of Diene, 13.1.2c 85
Figure 13.1.4 Crystal Structure of Catechol Silyl Substituted Cycloadduct,
13.1.1d 86
Figure 13.1.5 Semi-empirical MO calculations 87
Figure 13.1.6 Crystal Structures of Silatranyl Cycloadduct, 13.1.3a, b 89
Figure 13.2.1 Schematic Representation of Cycloadduct (13.2.10b)
Stereochemistry 95
Figure 13.3.1 Crystal Structures of Cross-Coupled Cycloadduct, 13.3.2e 96
X
List of Schemes
Scheme – 1.0.1 Traditional Diels-Alder reaction showing preference for “endo”
selectivity 1
Scheme – 2.1.1 Bonding interactions between the large coefficients of termini 5
Scheme – 2.2.2 Resonance structure showing the outcome in regioselectivity 5
Scheme – 2.1.3 Effect of the EDG attached to the dienes in Diels-Alder reactions 6
Scheme – 2.2.1 “Cis” principle in Diels-Alder reactions 7
Scheme – 2.2.2 Effect of temperature (A) and Lewis acids (B) on stereo-
chemistry 8
Scheme – 2.2.3 Coordination effect of the Lewis acid on stereochemistry 9
Scheme – 2.2.4 Transition-Metal influence on regiochemistry 9
Scheme – 2.2.5 Stereochemical considerations (Alder’s endo rule) of transition
metalated dienes 10
Scheme – 2.2.6 Chromium-Metal mediated [6+4] cycloaddition reactions 10
Scheme – 2.3.1 Enantioselectivity in Diels-Alder reactions 11
Scheme – 2.3.2 Enantioselective asymmetric synthesis of natural product,
Gracilin B 12
Scheme – 3.1 Few natural products accessible through [6+4] and [4+2]
cycloadditiion reactions 13
Scheme – 4.1.1 Higher-Order cycloaddition reactions of simple tropones and
transformation of cycloadducts 15
Scheme – 4.1.2 Cycloaddition reaction of (E)-1-trimethylsilyloxy-1,3-diene with
tropone 16
Scheme – 4.1.3 Cycloaddition reaction of (E) and (Z)-1-acetoxy-1,3-diene with
tropone 16
Scheme – 4.1.4 Tropones with substituents at bond forming centers 17
Scheme – 4.1.5 Influence of tropones bearing EWG in [6+4] cycloaddition
reactions 17
XI
Scheme – 4.1.6 Influence of tropones bearing EDG in [6+4] cycloaddition
reactions 17
Scheme – 4.1.7 Influence of Lewis acid catalyst on [6+4] cycloaddition reactions 18
Scheme – 4.1.8 Effect of Lewis acid catalysis on tropones substituted at
bond-forming centers 18
Scheme – 4.1.9 Tethered diene at 2-position of the tropone used towards the
synthesis of ABC tricyclic core of Ingenane terpenoids 19
Scheme – 4.1.10 Chromium-Metal mediated higher-order cycloaddition
reactions 20
Scheme – 4.1.11 Chromium (0)-catalyzed higher-order cycloaddition reactions 20
Scheme – 4.1.12 Synthesis of chiral auxillaries to promote chromium (0)-mediated
higher-order cycloaddition reactions 22
Scheme – 4.1.13 Reactions of auxillary directed and metal-promoted higher-order
cycloaddition reactions 23
Scheme – 5.1.1 Synthesis of cobolaxime dienes, 5.1.1a-e 25
Scheme – 5.2.1 [6+4] Cycloaddition reactions of tropones (5.1.2a) with
cobaloxime dienes 26
Scheme – 5.2.2 [6+4] Cycloaddition reactions of 2-substituted tropones with
cobaloxime diene 28
Scheme – 5.4.1 Representative example for demetallation reaction of [6+4]
cycloadduct 33
Scheme – 9.1.1 First reported synthesis (in-situ) of 1-trimethylsilyl-1,3-
butadienes 51
Scheme – 9.1.2 Poor regioselectivity due to electron poor and non-steric silyl
group in Diels-Alder reactions 51
Scheme – 9.1.3 Olefination of vinylsilyl carbonyl compounds using Grignard
reagents 52
Scheme – 9.1.4 Olefination of α, β-unsaturated carbonyl compounds using
1,1-bis(trimethylsilyl)methyllithium 52
XII
Scheme – 9.1.5 Olefination of carbonyl compounds using 1,3-bis(trimethylsilyl)-
propenyllithium 53
Scheme – 9.1.6 Synthesis of trimethylsilyl dienes by pyrolysis of 3-sulfolenes 53
Scheme – 9.1.7 Synthesis of 2-trimethylsilyl-1,3-butadienes using Grignard
addition reaction 54
Scheme – 9.2.1 Hydrosilylation of 1,4-dichlorobutyne using chloroplatinic acid 54
Scheme – 9.2.2 Synthesis of trimethylsilyl diene from 2-bromoallylbromide in
presence of nickel catalyst 55
Scheme – 9.2.3 Synthesis of trimethyl-[(E)-4-phenylbuta-1,3-dien-2-yl]silane 55
Scheme – 9.2.4 Tandem Pd-catalyzed elimination and cyclization reactions of
allylic acetates 56
Scheme – 9.2.5 Synthesis of silylstyrenes and silylbutadienes from dithioacetals
using nickel catalyst 57
Scheme – 9.2.6 Synthesis of (Z)-exocyclic silyl dienes by Ni(0) catalyzed hydro-
silylation of 1,7-diynes 58
Scheme – 9.2.7 Synthesis of 2-aryl-3-trimethylsilyl-1,3-butadienes 59
Scheme – 9.2.8 Synthesis of silyl dienes and Type-1 IMDA reactions of tethered
silyl dienes 60
Scheme – 9.2.9 Type-2 IMDA reactions of tethered silyl dienes 61
Scheme – 9.2.10 Synthesis of oxasilacyclopentene and its cycloaddition reactions
with 9.1.4b 61
Scheme – 9.2.11 Synthesis of siloxacycles, 9.2.29 62
Scheme – 10.1 Schematic representation of cross-coupling reactions 62
Scheme – 10.1.1 Non-activated desilylative cross-coupling reactions leading to
regioisomers 64
Scheme – 10.1.2 First report on fluoride-assisted regiospecific cross-coupling
reaction 64
Scheme – 10.1.3 Cross-coupling reactions of alkenylfluorosilanes 65
XIII
Scheme – 10.1.4 “Cine product” formation and group effect in Hiyama coupling
reactions 65
Scheme – 10.1.5 Cross-coupling reactions of dichloroalkylvinylsilanes using –OH
as activator 66
Scheme – 10.1.6 Synthesis of 1,3-dienes by cross-coupling reactions 66
Scheme – 10.1.7 Synthesis of siletanes 67
Scheme – 10.1.8 Cross-coupling reactions of alkenylsiletanes in mild conditions 67
Scheme – 10.1.9 Synthesis of highly substituted alkenes from silanols by
cross-coupling 68
Scheme – 10.1.10 Synthesis of (α-alkoxyalkenyl)silanols 69
Scheme – 10.1.11 Cross-coupling reactions of (α-alkoxyalkenyl)silanols 69
Scheme – 10.1.12 Synthesis of silylethers by hydrosilylation and its cross-coupling
reactions 69
Scheme – 10.1.13 Cross-coupling reactions of trialkoxyorganosilanes 70
Scheme – 10.1.14 Synthesis of trialkoxyorganosilanes by nucleophillic addition
reactions 70
Scheme – 10.1.15 Synthesis of trialkoxyorganosilanes by hydrosilylation using
Pd(0) and Rh(I) 70
Scheme – 10.1.16 Synthesis of bis(catechol)trialkoxyorganosilicates and their
cross-coupling 71
Scheme – 10.2.1 Cross-coupling reactions of alkenylsilanols in presence of
silveroxides 72
Scheme – 10.2.2 Enhanced reactivity of the silanols (> one –OH on silicon
moiety) 72
Scheme – 10.2.3 Cross-coupling reactions of alkenyl(aryl)[2-(hydroxymethyl)-
phenyl]dimethylsilanes 73
Scheme – 10.2.4 First report on silicon recovery after cross-coupling reactions 73
Scheme – 10.2.5 Silicon-Mannich reactions for synthesis of pentafluorophenyl-
methylamines 74
XIV
Scheme – 11.1.1 Representative example for tandem reactions and their
applications in natural product synthesis 74
Scheme – 11.2.1 Schematic representation of domino reactions 75
Scheme – 11.3.1 Synthesis of 2-(trialkoxysilyl)buta-1,3-diene 76
Scheme – 12.1 Schematic representation of the Hiyama coupling reaction 77
Scheme – 12.2 Proposed catalytic cycle (Exo-selective Diels-Alder and cross-
coupling reactions) 78
Scheme – 12.3 Proposed reaction mechanism for catalytic exo & enantio
selective Diels-Alder reactions 79
Scheme – 13.1.1 Synthesis of 2-alkyl(aryl)siloxy buta-1,3-dienes 82
Scheme – 13.1.2 Comparative study of reactivities of various silyldienes 85
Scheme – 13.2.1 Synthesis of allenic alcohols (13.2.2a, b) from propargylic
alcohols 90
Scheme – 13.2.2 Synthesis of trimethyl-[(E)-4-phenyl-1,3-butadien-2-yl]sialne,
(13.2.4a) 91
Scheme – 13.2.3 Synthesis of (1-cyclohexenylvinyl)trimethylsilane (13.2.4b) 91
Scheme – 13.2.4 Synthesis of siloxacyclopentene containing 1,3-dienes from
pentenyne 92
Scheme – 13.2.5 Synthesis of diisopropylsilyloxy substituted enynes (13.2.9a, c-d)
and siloxacyclopentene containing 1,3-dienes (13.2.4c) 92
Scheme – 13.2.6 Synthesis of diisopropylsilyloxy substituted enynes (13.2.9e) and
siloxacyclopentene containing 1,3-dienes (13.2.4d) 93
Scheme – 13.2.7 Synthesis (tandem) of dimethyl siloxacyclopentene containing
1,3-dienes (13.2.4e, f) 93
Scheme – 13.2.8 Intermolecular Diels-Alder reactions of diene–13.2.4c, with
N-phenylmaleimide 94
Scheme – 13.3.1 Cross-coupling reactions of silatrane substituted silyl
cycloadduct, 13.1.1c 95
XV
Scheme – 13.3.2 Cross-coupling reactions of bis-catechol substituted silyl
cycloadduct, 13.1.1d 96
Scheme – 13.3.3 One-pot, domino reaction of silatrane substituted
silyl 1,3-butadiene (13.1.2a) 97
Scheme – 14.1.1 Various substituted dienophiles and cross-coupling reagents 98
Scheme – 14.1.2 Proposed catalytic cycle for domino/tandem Diels-Alder, and
cross-coupling reactions 99
Scheme – 14.1.3 Synthetic route for the preparation of Pt(II) catalysts 100
Scheme – 14.1.4 Synthesis of palladocycle catalyst 100
Scheme – 14.1.5 Proposed pathway for the synthesis of alkoxysilyldienes (Tamao
protocol) 101
Scheme – 14.1.6 Proposed reaction pathway for synthesis of alkoxysilyldienes 101
Scheme – 14.1.7 Synthesis of trialkoxysilyldienes by hydrosilylation of halodienes 102
Scheme – 14.1.8 Enyne cross-metathesis reaction for synthesis of
trialkoxysilyldiene 102
Scheme – 14.1.9 Synthesis of trialkoxysilyldiene by Kumuda reactions 103
Scheme – 14.1.10 Proposed synthesis methodology for synthesis of 1,2-substituted
halo dienes 103
Scheme – 14.1.11 Rhodium-catalyzed asymmetric 1,4-addition of organosilanes 104
Scheme – 14.1.12 Proposed catalytic asymmetric Diels-Alder and 1,4-addition
reaction mechanism 104
XVI
List of Abbreviations
DDQ 2,3-dichloro-5,6-dicyanobenzoquinone
Ac2O Acetic anhydride
MeCN Acetonitrile
Ac Acetyl
Ar Aryl
Bp Boiling point
13C APT Carbon-13 Attached Proton Test
13C DEPT Carbon-13 Distortionless Enhancement by Polarization Transfer
J Coupling constant
Tropone Cycloheptatrienone
dec Decomposes
DIBAL-H Diisobutylaluminium hydride
DMAP Dimethylamino pyridine
DMF Dimethylformamide
DMG Dimethylglyoxime
DMSO Dimethylsulfoxide
DPG Diphenylglyoxime
EDG Electron donating group
EWG Electron withdrawing group
Et Ethyl
EtOH Ethyl alcohol
EtOAc Ethyl acetate
XVII
GCMS Gas Chromatography Mass Spectrometry
HMBC Heteronuclear Multiple Bond Coherence
HMQC Heteronuclear Multiple Quantum Coherence
HMPA Hexamethylphosphoramide
HRMS High Resolution Mass Spectrometry
COSY Homonuclear Correlation Spectroscopy
IR Infrared
IMDA Intra-Molecular Diels-Alder
iPr isopropyl
LCMS Liquid Chromatography Mass Spectrometry
Mg* Magnesium, activated
mp Melting point
Me Methyl
NBS N-bromosuccinimide
nBuLi n-Butyllithium
NMP N-Methyl-2-pyrrolidone
NMR Nuclear Magnetic Reseonance
NOESY Nuclear Overhauser Effect Spectroscopy
OAc¯
acetate
Ph Phenyl
Py Pyridine
Rf Retention factor
XVIII
sBu Secondary butyl
tBu Tertiary butyl
THF Tetrahydrofuran
THP Tetrahydropyran
TBAF Tetra-n-butylammonium fluoride
TMS Tetramethylsilane
TMSCl Trimethylsilyl chloride
TPP Triphenylphosphine
TASF Tris(dimethylamino)sulfonium difluorotrimethylsilicate
XIX
ABSTRACT
Pidaparthi, Ramakrishna Reddy
TRANSITION METAL MEDIATED, STEREOSELECTIVE
HIGHER-ORDER [6+4] AND DIELS-ALDER [4+2]
REACTIONS: SYNTHESIS OF NOVEL 2-SILYL SUBSTITUTED-
1,3-DIENYL COMPOUNDS & THEIR DOMINO REACTIONS
Dissertation under the direction of Mark E. Welker, Ph. D., William L. Poteat Professor of
Chemistry
We have prepared various substituted cobaloxime dienes and studied extensively their
reactivities in Diels-Alder reactions. Based on the studies with cobaloxime chemistry, we
concluded that increased exo selectivities were possible with the insertion of the transition
metals in the 2-position of the diene moiety. In the first part of this study, we will describe the
higher-order [6+4] and Diels-Alder [4+2] reactions of the cobaloxime dienes with various
tropones. The reaction pathway [6+4 vs 4+2] largely depends on the substituents on the tropone
moiety where as the stero and regioselectivity is determined only by the cobaloxime.
In order to overcome the problems persisting with those dienes in catalytic reactions,
we have now moved on to main group element substituted dienyl compounds which are benign
to nature, easy to handle and mild in reactivities. These main group element substituted dienes
can be transmetalated efficiently to catalytic quantities of transition metals in order to get all
the enhanced selectivities mentioned above. We have already established the pathway by using
boron substituted dienes. Herein, we describe various methods used in the synthesis of stable
silyl dienes from inexpensive starting materials and show their improved regio and
stereoselective reactions in Diels-Alder, cross-coupling, and domino reactions.
1
A, B = need not be carbon / c,c double bond; R1,R2,R3,R4 ≠ Η
∗
∗
∗
∗
∗ = stereochemistry was not shown at the stereo centers
R1
B
A
R4
R3
A
B
R1R4
R3
R2
+
R2
Diels-Alder
Figure - 1.0.1: Diels-Alder reaction with formation of "F OUR" stereocenters
CHAPTER 1 INTRODUCTION: OVERVIEW OF TRADITIONAL DIELS-ALDER REACTIONS
Although the mechanism of the reaction was not described, Wieland first reported the
cycloaddition (dimerization) of the conjugated dienes.[1, 2] In 1928 Diels and Alder[3] defined the
scope and mechanism of the cycloaddition reaction between cyclopentadiene (1.0.1a) with
quinone (1.0.2) for which they were rewarded with the Nobel Prize in chemistry (1950) and the
reaction later on would bear their names (Scheme-1.0.1).[4]
These reactions are ubiquitous in organic synthesis due to their ability to construct six-
membered cyclic structures with 2–4 consecutive stereocenters. During the course of the
reaction the stereochemistry of the dienophile was maintained. In general, these reactions are
thermodynamically favorable and exothermic where two new ‘σ’ bonds were formed with the
expense of two ‘π’ bonds (Figure 1.0.1).
2
1.0) Mechanistic Aspects. Two factors govern the outcome of the Diels-Alder reactions.
One is the sterics and the other is electronics. Under normal reaction conditions, aliphatic
dienes exist largely in the ‘S-trans’ conformation in order to minimize steric interactions in
between the terminal substituents, but it can rotate to the ‘S-cis’ conformation at elevated
conditions, which ultimately promote the facile Diels-Alder reactions (Figure 1.0.2).
Enhanced reactivity towards cycloadditions has been achieved by either employing 2-
transmetalated dienes[5] (Figure 1.0.3) or by using cisoid dienes (Figure 1.0.4).[6]
3
LUMO ofdiene
bondinginteraction
LUMO ofdienophile
HOMO ofdienophile
HOMO of
diene
bondinginteraction
A B
The electronic effect in the Diels-Alder reactions can be explained by Frontier
Molecular Orbital (FMO) theory.[7-12] In the normal demand Diels-Alder reactions, the Highest
Occupied Molecular Orbital (HOMO) of the diene interacts with the Lowest Unoccupied
Molecular Orbital (LUMO) of the dienophile. In the case of inverse electron-demand Diels-Alder
reactions, the LUMO of the diene interacts with the HOMO of the dienophile. Both of the
reactions happen suprafacially with respect to reacting components and are termed [π4s+π2s]
reactions. This reaction is a symmetry-allowed reaction and governed by the Woodward-
Hoffmann rules (Figure 1.0.5).[13]
Based on the electronic nature of the groups attached to the diene and dienophile one
can easily predict the reaction pathway they will undergo (Figure 1.0.6).[6, 14]
Figure - 1.0.6: Classification of Diels-Alder reactions based on FMO analysis
Figure - 1.0.5: FMO Diagrams for normal (A) and inverse (B) electron demand Diels-Alder reactions
4
2.0) Stereochemical Aspects. The versatility of the Diels-Alder reaction lies in its
stereoselectivity. These reactions will work under different conditions with the utilization of a
wide range of diene and dienophile systems. Based upon the selectivity, the possible product
outcomes of these reactions can be subdivided into three groups: regioselectivity,
diastereoselectivity, and enantioselectivity.
2.1) Regioselectivity. In general, with the use of unsymmetrical dienes and dienophiles we can
expect the formation of two regioisomers with equal propensity. But in reality formation of one
isomer is predominant over the other. This can be explained with the aid of FMO theory, which
takes into consideration of orbital coefficients altered by the groups attached to the reacting
partners.[8] Based on the FMO theory, Houk[11] proposed two assumptions to predict the
outcome of the regiochemistry.
� Stabilization of the transition state primarily occurs from the interactions of HOMO-
LUMO pairs of molecular orbitals, which are closest in energy.
� Preferentially, the termini with a larger coefficient undergo the bonding interactions
during the transition state.
From the above assumptions, prediction of the major regioisomer in the Diels-Alder
reactions is possible. For example, the reaction between 2-ethoxybutadiene (2.1.1) and methyl
acrylate (2.1.2) yields the para isomer as the major regioisomer due to higher differences in the
HOMO diene terminal coefficients. Whereas in the case of 2-cyanobutadiene (2.1.3) and methyl
acrylate (2.1.2), low regioselectivity is predicted due to a smaller difference between the diene
terminal coefficients (Scheme-2.1.1).[8]
5
0.585
-0.563
0.636
-0.572
-0.19
0.68
EtOO
OMeNC
HOMO LUMO
2.1.1 2.1.3 2.1.2
EtO
OMe
O
OrthoMeta
Para
NC
OMe
O
OrthoMeta
Para
NCOrtho
Meta
Para+
O
OMe
EtO
O
OMe
NC
O
OMe
Scheme - 2.1.1: Bonding interactions between the large coefficients of termini
2.1.3 + 2.1.2
2.1.1 +2.1.2
C
N
CN
CN
100 °C, 12h30%
+
+
Ratio: 9 : 1
Another easy way to predict the regiochemical outcome is with zwitterionic drawings
(resonance) (Scheme-2.1.2).
Scheme - 2.1.2: Resonance structure showing the outcome in regioselectivity
6 Regioselectivity also relies on the position of the electron donating groups (EDG)
attached to the diene participating in the Diels-Alder reactions (Scheme-2.1.3).[6]
Y
+
X
Y
Complementary substitution (1,3-disubstituted dienes) provides even greater regioselectivity:
X'
X
X'
ortho to X' groupand para to X group
Y
+
X X
Y
X Y
+
Non-complementary substitution (1,2-disubstituted dienes) results in poor regioselectivity:
X' X' X'
relative amounts depend on electrondonating strength of X and X'
Scheme - 2.1.3: Effect of the EDG attached to the dienes in Diels-Alder reactions
7
2.2) Diastereoselectivity. The most important factor making the Diels-Alder reaction an
important tool in over all organic reactions is its diastereoselectivity. The diastereoselectivity
can be explained as the approach of the dienophile towards the diene during the formation of
the cycloadducts. The likely formation of the diastereomers were identified with the aid of two
principles brought forward by Alder and Stein.[15]
a) Cis principle: The relative configuration of the reacting diene and dienophile are
maintained in Diels-Alder cycloadducts (Scheme-2.2.1).[6]
b) Alder’s endo rule: The approach of the diene and dienophile in the Diels-Alder
reactions is possible by two means. If the EWG of the dienophile was kept away from the diene
during the reaction, the formation of the thermodynamically stable cycloadduct through the exo
transition state results where as if the EWG of the reacting dienophile is tucked underneath the
diene during the reaction the cycloadduct through the endo transition state results (Figure
2.2.1).[5]
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
MeO2C
CO2Me
CO2Me
X
X
X
X
R
R
R
R
+
+
+
Scheme - 2.2.1: "Cis" principle in Diels-Alder reactions
8
Figure - 2.2.1: Stereochemical considerations (Alder's endo rule)
EWG
H
EWG EWG
EWG
H
EWG
EWG
=
+
Endo:
=
+
∆
∆
Exo:
The formation of endo-adduct (kinetic product) is more likely in regular organic
reactions. This effect can be explained by the secondary orbital interactions during the transition
states where maximum overlap of the orbitals takes place (Figure 2.2.2).[11]
O OEndo cycloadduct Exo cycloadduct
Figure - 2.2.2: Maximum overlap of orbitals enhance the "endo" selectivity
Endo-selectivity can be improved in the Diels-Alder reactions by altering the reaction
conditions like working at high pressure and / or low temperature or by employing Lewis acids
(Scheme-2.2.2).[16]
9 Addition of Lewis acids enhances diastereo- and regioselectivities. In the following
example (Scheme-2.2.3), the high selectivity was observed by using SnCl4 presumably due to its
bidentate coordination ability over the other Lewis acid, boron trifluoroetherate.
Our group has shown that using metal templates having bulky ligands on the diene
partners makes the dienophile approach through exo transition states in order to minimize the
steric interactions between the EWG and the ligands of the metal (Scheme-2.24).[17-19] This
results in the formation of anti products which are difficult to prepare in traditional Diels-Alder
reactions of (Z)-dienes. The formed anti product has the same stereochemistry that would have
been obtained with the (Z)-dienes in metal-free Diels-Alder reactions (Scheme-2.2.5).
10
H
H H
H
EWGH
HEWG
EWG
H
LnM
H
EWGH
EWGEWG
MLnM
=
typically does notwork well (anti product)
"Z" diene
+
Scheme - 2.2.5: Stereochemical considerations (Alder's endo rule) of transition metalated dienes
=
L
L
LL
+
An alternative route toanti diastereomers
The bulk of a metal's ligand set is used to d irect exo selective cycloadditions!
Exo:
Endo:
∆
Rigby’s group use a different approach to reverse the exo/endo selectivities in higher-order
cycloaddition reactions.[20-22] They chose chromium metal to block one face of the
cycloheptatriene (2.2.1) by making η6-complex (2.2.2). This complex 2.2.2 has shown
preferential reactivity with various dienes to yield higher-order cycloadducts (2.2.3a-f) through
exclusively endo transition states where the traditional cycloaddition (organic) reactions tend to
give the cycloadducts through exo transition states (Scheme-2.2.6).
11
2.3) Enantioselectivity. The dienophile can approach in an endo (or) exo orientation
from the top face or the bottom face of the diene (difference in facial approach of the diene)
resulting in enantiomers (Scheme-2.3.1).
Enantioselectivity can be improved by blocking one face of the diene or dienophile with
chiral auxiliaries.[8] Chiral Lewis acid catalysts and optically active chiral transition metal
dienes[23] have been extensively studied. Recent studies have shown the importance of using
the chiral Lewis acid catalysts[24-26] compared to the earlier stoichiometric chiral auxiliary
mediated asymmetric synthetic reactions and can be effectively employed in total synthesis
(Scheme-2.3.2).[27]
12
Having the experience using cobaloxime to induce exo stereoselective synthesis as
mentioned above, we wanted to see how they react with various tropones as 6π system in
higher-order cycloaddition reactions. Precise background information and our experimental
observations in this area would follow this section.
Scheme-2.3.2: Enantioselective asymmetric synthesis of natural product, Gracilin B
TMS
N
F3CO2SNAl
NSO2CF3
ArAr
N
O
O
t-Bu TMSO
O
t-BuH
H
+Ar = 3,5-dimethylphenyl
toluene, -78°C
O
TMSOMe
OMe
H
H
HO2C
HO2CO
OMe
OMe
H
H
O
H
H
H
H
O
O
MeO
O
MeSO3HO
H
H
H
H
O
O
AcO
O
AcO
Gracilin B
89%, 95% ee
(20 mol %)
13
CHAPTER 2
TRANSITION METAL MEDIATED, STEREOSELECTIVE HIGHER-ORDER [6+4]
AND DIELS-ALDER [4+2] REACTIONS
3) Introduction.
Higher-Order cycloaddition reactions are known for assembling complex molecules with
polycyclic carbon skeletons and predictable stereochemistry. The major drawback arises from
low yields due to lack of periselectivity, which can be overcome by tying the reacting centers
together to take advantage of intramolecularity by employing metal templates.[28] In general,
free tropones as 6π components with the regular organic diene partners leads to [6+4]
cycloaddition through exo-transition states,[29, 30] where as metal complexed tropones give the
cycloadducts through endo-transition states.[28]
Cobaloxime dienyl complexes[31] are well known for highly exo- selective Diels-Alder reactions
with various dienophiles. Our recent work involves one pot synthesis of cobaloxime dienyl
complexes and study of their unusual cycloaddition reactions with tropones. The cycloadducts
were formed with moderate to high yields through higher order [6+4] or [4+2] cycloadditions
dictated by the substituents present on the 6π system. The [6+4] cycloadditions are
stereocomplementary to those reported by the Rigby group.[28] The cycloadducts from [6+4] and
[4+2] cycloadditions have been shown to provide access to the core structures in natural
products (Scheme-3.1) viz. Guanacastepene (3.1.1),[32] Guadalupol (3.1.2a),[33] Epiguadalupol
(3.1.2b),[33] Mulin-12,14-dien-11-on-20-oic acid (3.1.3),[34] and Ingenol (3.1.4).[35, 36]
14
4.1) Higher-Order Cycloaddition Reactions using 6π and 4π
Components. Having similar utilities in organic synthesis compared to the well known Diels-
Alder reactions, higher-order cycloaddition reactions became an important tool in attaining
higher stereoselectivities, molecular complexity and the ability to substantial functionalization
of both the reacting partners. However, these reactions are limited by the lack of periselectivity
that ultimately results in low yields of the desired cycloadducts. Using 6π and 4π components in
the reactions often leads to multiple competitive pericyclic reactions which will result in several
cycloadducts. Due to the synthetic advantages offered by this class of cycloadditions, other
groups have reported recent developments, including metal mediations which have successfully
addressed the periselectivity.[12, 37-40] Based on the use of transition metals, higher-order
cycloadditions involving 6π and 4π components are subdivided into two main categories, viz.
metal-free tropones in higher-order cycloaddition reactions and metal-mediated tropones in
higher-order cycloaddition reactions.
4.2) Metal-free Tropones in Higher-Order Cycloaddition Reactions.
Cycloaddition reactions of tropones and related cyclic trienes with 4π reaction partners can
offer easy access to functionalized bicyclic products that are difficult or impossible to make by
other means. In contrast, most of the cyclic triene reacting partners such as 1,3,5-
cycloheptatriene and azepine are poor 6π reacting partners in thermal, metal-free higher-order
cycloaddition reactions and offer limited synthetic advantage. The thermally induced [6+4]
cycloaddition reactions reported by Ito and co-workers[41] between 2,4,6-cycloheptatrienone
(tropone) (5.2.1a) with butadiene (4.1.2) derived from sulfolene (4.1.1) at 130 °C in xylenes for
10h resulted in two types of adducts through exo transition states. The [6+4] adduct was
obtained as a major isomer (4.1.3a) in 75% yield and the [4+2] adduct was obtained in 9% yield.
15 Further they showed that these adducts could undergo dehydrogenation (4.1.5a-c), reduction
(4.1.6a,b), acetylation (4.1.7a-c) and bromination (4.1.8a,b) to yield other bicyclicundecanes
that are useful building blocks in natural product synthesis (Scheme-4.1.1).
A reaction (Scheme-4.1.2) between tropone (5.2.1a) and (E)-1-trimethylsilyloxy-1,3-
butadiene (4.1.9a) at various temperatures showed that extended reaction times or higher
temperatures tended to enhance the yields at the expense of higher-order adducts and often an
alternative [4+2] reaction pathway prevailed under harsher conditions.[42, 43] In benzene at reflux
conditions, the electron-rich diene yielded [6+4] cycloadduct in higher yields, but treating the
same reagents in xylenes at refluxing temperature resulted only in the [4+2] adduct.
S
OO
4.1.1
4.1.2O
O
O
Br
Br
O
H
BrBr
H
O
5.2.1a
+
O
4.1.3a 4.1.4
∆∆∆∆
O
NaBH4
HO
OH
+
H
H
AcO
H
DDQ
NBS
OAc
OAc
Br2+
Me
MeO
4.1.3c
O
4.1.3b
Me
DDQ
O
Me
MeDDQ
O
Me
4.1.5a
4.1.5b
DDQ
4.1.5c
Ac2O
4.1.3a
Scheme - 4.1.1: Higher-Order cycloaddition reactions of simple tropones and transformation of cycloadducts
4.1.7c
4.1.6a 4.1.7b4.1.7a4.1.8a
4.1.8b4.1.6b
16
Garst et al.[42] studied the effects of 1-substituted dienes by varying the electronic nature
of the dienes in cycloaddition reactions with tropones. Even small structural changes on either
reaction partner can have profound effects on the periselectivity of these transformations
(Scheme-4.1.3). For example, reacting tropone (5.2.1a) with (E)-1-acetoxy-1,3-butadienes
(4.1.11a) resulted in only one isomer (4.1.12a). Whereas the same transformation using (Z)-1-
acetoxy-1,3-butadienes (4.1.11b) resulted in only a smaller amount of [6+4] adduct (4.1.12c)
along with a major adduct having a mixture of isomeric products (4.1.12b) through [4+2]
cycloaddition.
Among all the ten dienes they used in their study, the reactions carried out under 200 ⁰C
favoured [6+4] additions and the yields ranged from 60-80%. The conclusions based on their
study of these cycloaddition reactions are that the [6+4] adducts are formed through an exo
transition state and the [4+2] cycloadditions will happen through an endo transition state. In
[6+4] cycloaddition reactions, only two of these distinct adducts are formed from dienes
differing only in stereochemistry. The rate of the [6+4] addition reaction depends on the
electron density of the diene. Cycloadducts formed from electron-rich dienes are
OOAcO
HH
OAc
O
AcO
1 2
3
45
6
7
1'
2'3'
4'
5
67
12
3
4
12
3
45
6
7
1'
2'3'
4'
1'
2'3'
4'4.1.11a
5.2.1a4.1.12a (59%) 4.1.12b (50%)
Scheme - 4.1.3: Cycloaddition reaction of (E) and (Z)-1-acetoxy-1,3-diene with tropone
AcO
1'
2'3'
4'
4.1.11b
O
HH
OAc1
2
3
45
6
7
1'
2'3'
4'
4.1.12c (12%)
+
O OTMSO
HH
OTMS
O
OTMS
1 2
3
45
6
7 1'2'
3'
4'5
67
12
3
4
12
3
45
6
7
1'
2'3'
4'
1'
2'3'
4'+
Benzene
∆∆∆∆∆∆∆∆
Xylene
4.1.9a5.2.1a4.1.10a 4.1.10b
Scheme - 4.1.2: Cycloaddition reaction of (E)-1-trimethylsilyloxy-1,3-diene with tropone
17
O
+
160 °°°°C1 2
3
45
6
7 1' 2'
3'4'
+
4.1.154.1.17b 4.1.18b (15%)
Scheme - 4.1.6: Influence of tropones bearing EDG in [6+4] cycloaddition reactions
OMe
O
HH 12
3
45
6
7
1'
2'3'
4'
4.1.18a (15%)
OMe
Me
Me
O
HH 12
3
45
6
7
1'
2'3'
4'
OMe
Me
thermodynamically less stable when compared to cycloadducts resulting from electron-poor
dienes.
Substituents at the bond forming centers of the tropones (4.1.13) are known to inhibit the
higher-order cycloaddition pathway (Scheme-4.1.4) as shown in the following example.[44, 45]
Electronically influencing substituents located on the tropone nucleus other than bond
forming centers strongly influence the regiochemical outcome. Tropones with electron
withdrawing groups (EWG) undergo [6+4] cycloaddition qualitatively parallel to Diels-Alder [4+2]
reaction (Scheme-4.1.5) in modest yields.
Tropones having electron donating groups (EDG) exhibit both low regioselectivity and
poor chemical yields (Scheme-4.1.6) suggesting the electronic nature of the reactants on
tropones influence the outcome and mode of reaction pathway.
OCl
+
150 °°°°C
OCl
1
2
3
45
6
71'
2'3'
4'
5'
1
23
4
5
67
2'
3'
4'
5'
1'
O
Cl
1
2
3
45
6
72'
3'
4'
5'1'
+
1.0.1a4.1.13 4.1.14a (11%) 4.1.14b (30%)
Scheme - 4.1.4: Tropones with substituents at bond forming centers
O
+
110 °°°°C1 2
3
45
6
7 1'2'
3'4'
O
1
2
3
45
6
7
2'+
4.1.11a4.1.15 4.1.16b (10%)
Scheme - 4.1.5: Influence of tropones bearing EWG in [6+4] cycloaddition reactions
OAc
OAcCO2Et
O
HH
OAc1
23
45
6
7
1'
2'3'
4'
4.1.16a (20%)
CO2Et
EtO2C
18 Gleason and co-workers on their work (Scheme-4.1.7) towards the synthesis of
carbocyclic core of CP-225,917 and CP-263,114 reported the use of lewis acid in promoting the
facile [6+4] cycloaddition reactions of cyclopentadiene (1.0.1a) and 2-triethylsilyloxy-
cyclopentadiene (1.0.1b) with tropones having EWG at 3 and 4 positions (4.1.19).[46]
Another interesting finding in this study is that the Lewis acid assisted higher-order
cycloaddition reactions are also possible with tropones having substitutents at the bond-forming
centers as well. In these reactions, the [6+4] adduct was isolated in quatitative yields and the
reaction was progressed instantaneously with the aid of ZnCl2 in Et2O (Scheme-4.1.8).
O
+
1 2
3
4
5
6
7
4.1.19
CO2Me
O
1'
2'3'
4'
5'
1
2 3
4
5
672'
3'
4'
5'
1'+
CO2Me
CO2Me
R1CO2Me
1.0.1a, R1 = H
1.0.1b, R1 = OTMS
O
1
2 3
4
5
672'
3'
4'
5'
1'+
4.1.19a, b (1:1, 65%)
CO2Me
CO2Me
O
O
1
2 3
4
5
67
2'
3' 4'
5'
1'CO2Me
CO2MeO
Condition a: Tol, ∆, 2 h, 4.1.20a, b (1.5:1, 51%)
b: 10% ZnCl2, Et2O, 3 h, 4.1.19a, b (3:1, 62%)
O
1
2
3
4 5
6
7
2'3'
4'
5'1'
MeO2C
MeO2C
a or b
b
Condition b: 10% ZnCl2, Et2O, 3 h, 4.1.21a, b (1:1, 65%)
Scheme - 4.1.7: Influence of Lewis acid catalyst on [6+4] cycloaddition reactions
O
+
1 2
3
4
5
6
7
4.1.22a-c
R2 1'
2'3'
4'
5'
OTESR3
1.0.1b O
1
2 3
4
5
672'
3'
4'
5'
1'
R3
R2
O
4.1.23a (70%), R2 = CO2Me, R3 = R4 = H
4.1.23a (82%), R3 = CO2Me, R2 = R4 = H
4.1.23a (88%), R4 = CO2Me, R2 = R3 = H
R1
ZnCl2
Et2O
R1
Scheme - 4.1.8: Effect of Lewis acid catalysis on tropones substituted at bond-forming centers
19 Tethering the diene and triene components is another interesting phenomenon
addressed in higher-order cycloaddition reactions in order to prevent the competing Diels-Alder
reactions that are common when tropones having substituents at the 2-position were
employed. Rigby et al.[43] showed that using a three-carbon spacer tethered at the 2-position of
tropone allows one to construct the ABC tricyclic system of ingenane diterpenoids (Scheme-
4.1.9) through exo stereoselectivity in high yields.
4.2) Metal-mediated Tropones in Higher-Order Cycloaddition Reactions.
We have found a very few examples involving transition metals in promoting [6+4] cycloaddition
reactions. Among the notable work on higher-order cycloaddition reactions, the Rigby group
reported several examples in the past two decades screening various group VI metals[47] (Cr, Mo,
W) and showed that chromium (0) is the best choice in promoting higher-order cycloaddition
reactions. These chromium-η6 cycloheptatriene complexes (2.2.2) were shown to be air-stable
and undergo [6+4] and [6+2] cycloadditions under photolytic conditions to yield cycloadducts in
high yields (Scheme-4.1.10). Subsequent demtallation could be carried out in the presence of
trimethyl phosphite. In all cases, the cycloadditions happened through endo transition states
resulting in anti-adducts which is not possible in traditional organic reactions involving metal-
free tropones.
1'
2'
3'
4'
5'
Scheme - 4.1.8: Tethered diene at 2-position of the tropone usedtowards the synthesis of ABC tricyclic core of Ingenane terpenoids
O1 2
3
4
5
6
76'
7'
80 °°°°CO
H 12
3
45
6
7
1'
2' 3'
4'5'
6'7'
H
4.1.244.1.25 (80%)
20
Later, in their studies in higher-order cycloadditions, Rigby et al. reported the thermal
reactions involving chromium (0) metal complexed cycloheptatriene.[48] These reactions resulted
in isolation of metal-free cycloadducts and prompted them to develop a catalytic version using
catalytic quantities of (η6-cycloheptatriene)tricarbonylchromium (2.2.2) with an excess (2-10
eq.) of 2π reacting partner (ethyl acrylate, 14.1.25) in refluxing alkyl ethers (nBu2O/tBuOMe) for
several hours (Scheme-4.1.11) to provide a mixture of [6+4] and [4+2] cycloadducts (4.1.26a, b)
in 10:1 ratio and 99% yield. Whereas, the absence of metal catalyst resulted in a mixture
comprised principally of 4.126b with only a trace of 4.1.26a.
Scheme - 4.1.10: Chromium-Metal mediated higher-order cycloaddition reactions
2.2.2
R
HH
Cr(CO)3
a (or) b
c, eHH
R
Conditions: a) Cr(CO)6, diglyme; b) (MeCN)3Cr(CO)3, THF
c) RC(H)=CH-CH=CH2, hυυυυ; d) RC(H)=CH2, hυυυυ; e) (MeO)3P
d, e
[6+4][6+2]
2.2.1
Scheme - 4.1.11: Chromium (0)-catalyzed higher-order cycloaddition reactions
4.1.26a
trace, [6+4 adduct]
2.2.1
b, cHH
EtO2C
Conditions: a) 15 mol% 2.2.2; b) CO2EtC(H)=CH2; c) nBu2O, 160 °°°°C, sealed tube
a, b, c1
2
34
5
67
1' 2'
1
2
34
5
6
7
12
34
5
6 7
1'
2'
CO2Et
+
4.1.26b
minor, [4+2 adduct]
HH
EtO2C
1
2
34
5
67
1' 2'
12
34
5
6 7
1'
2'
CO2Et
+
4.1.26a
major, [6+4 adduct]
4.1.26b
major, [4+2 adduct]
21 The catalytic cycle (Fig 4.1.1) clearly explains that the reaction solvent, nBu2O can serve
both to initiate ligand exchange and to regenerate the active metal complex, 4.1.27. Also, the
reduced rate of [6+4] addition compared to [6+2] reaction can be explained in terms of the
stabilities of the adduct-metal complexes.
Even though, the [6+4] cycloaddition reactions are slower than [6+2] cycloadditions, the
reaction can be best effected by exposing cycloheptatriene and the 4π reacting partner to
catalyst in which one of the CO ligands has been replaced with PPh3.[49] This finding is very
significant as it offers an opportunity to examine various chiral phosphine ligands to induce
asymmetry during the cycloaddition. The same group[50] has also reported an alternate protocol
for asymmetric synthesis to deliver optically active cycloadducts by preparing diasteromerically
enriched chromium (0) complexes that were prepared through face-selective complexation of a
chiral auxillary-substituted π-system. The tropilium ions (4.1.28) could be prepared from the
R2O
Cr(CO)3
CO2Et
Cr(CO)3
CO2Et
R2O
CO2Et
H
H(R2O)3Cr(CO)3
4.1.27
Figure - 4.1.1: Catalytic reaction pathway of chromium (0)-catalyzed higher-order cycloaddition reactions
22 known procedure[51] and derivatized with commercially available auxillaries and then
complexed with chromium carbonyl species (Scheme-4.1.12) using a standard protocol.
BF4R1H, NaH
Tol, r.t
R1
100 °°°°C 135 °°°°C
4.1.29a (65%) 4.1.30a (68%) 4.1.31a (55%)4.1.29b (50%) 4.1.30b (45%) 4.1.31b (60%)4.1.29c (90%) 4.1.30c (60%)
4.1.28
OH
Me
Me
Me
S
R
SS R
R
S
Me
OH
SR
R
Me
Me
Ph
MeMe
H
SNH
OO
R1H = a (isopinocampheol) b (8-phenylmenthol) c (camphorsultam)
R1
R1
R1 R1R1
12
3
4
56
7
1
2
34
5
6
71
2
34
5
6
7
12
3
4
5 6
7
12
3
4
56
7
12
3
4
56
7
Cr(CO)3 Cr(CO)3
+(MeCN)3Cr(CO)3
THF, r.t
4.1.31a 4.1.32a 4.1.33a (55%, Ratio, 4:1)4.1.31b 4.1.32b 4.1.33b (73%, Ratio, 6:1)
R1
1
2
34
5
6
7
(MeCN)3Cr(CO)3
THF, r.t
R1
1
2
34
5
6
7
Cr(CO)3
4.1.30c 4.1.34 (70%, >98%de)
Scheme - 4.1.12: Synthesis of chiral auxillaries to promote chromium (0)-mediated
higher-order cycloaddition reactions
Photochemically initiated [6+2] cycloaddition of 4.1.32a with ethyl acrylate (4.1.25)
afforded a single regioisomer (4.1.35) in quantitative yields with high diastereoselectivity.
Whereas the compound 4.1.34 with 4.1.25 under photolysis conditions, resulted in a 1:1
mixutre of regioisomeric adducts (4.1.36a, b) which are found to be diastereomerically in
23 pure form (Scheme-4.1.13) suggesting that the face-integrity of the metal-triene
complex remained intact through out the process.
We have found few other examples in which trienes have acted as 6π components to
undergo higher-order cycloadditions with various dienes to yield 6+4 cycloadducts. For example,
fulvenes are considered to be capable of undergoing multiple, competitive pericycyclic reactions
with various dienes in a similar manner to the cyclic triene systems. In general, fulvenes react
with electron-deficient dienes at one of the endocyclic double bonds in [4+2] reaction
pathways[40, 52] and with electron-rich dienes they will undergo higher-order [6+4]
cycloadditions.[38, 39, 53, 54] Also there are a few other reports describing 1,3-dipoles as equivalent
to 4π systems which react with tropones to yield [6+4] cycloadducts.[55] Even though these
reactions were considered to higher-order cycloadditions, these are beyond the limit of this
present study and hence they are not covered here.
Scheme - 4.1.13: Reactions of auxillary directed and metal-promoted higher-order cycloaddition reactions
CO2Et
R1 H
EtO2C
4.1.36a 4.1.36b 4.1.25 4.1.35
4.1.32a
hνννν
4.1.34HH
EtO2C CO2Et
R1R1
(82%, >98%de, 1:1) (86%, >98%de)
+ hνννν
1
2
3
4 5
6
7
1
2
3
45
6
7
1
2
3
45
6
7
24
5.0) Results and Discussion. Our group[56] and the Tada group[57] independently
reported the preparation and Diels-Alder reactions of pyridine cobaloxime dienyl complexes
over 10 years ago. Since that time, we have reported a number of synthetic routes to these and
other related types of cobalt dienyl complexes as well as their subsequent cycloaddition and
demetallation chemistry,[31, 58, 59] and other groups have now made use of the cycloadducts thus
prepared[60] as well as the methodology.[61]
Tropones are unusual cycloaddition electrophiles in that they can participate as 6π or 2π
electron partners in cycloadditons with organic dienes.[62] As discussed earlier, free tropones
react in [6 + 4] cycloadditon reactions with organic dienes through exo transition states[29, 46, 63, 64]
and the metal complexed tropones react with organic dienes through endo transition states.[28]
Reactions of metal substituted dienes with free tropones had not been investigated, hence the
studies we report here to elucidate both the mode ([6 + 4] versus [4 + 2]) and stereochemical
outcomes of these classes of cycloaddition reactions.
5.1) Synthesis of Cobaloxime Dienes. Cobaloxime dienyl complexes (5.1.1b-e) used in this
study were prepared using zinc mediated hydrocobaltation of enynes as we have reported
previously.[31] We extensively studied rates of Z-diene to E-diene isomerization relative to
cycloaddition rates in our earlier cobaloxime Diels-Alder chemistry.[65] Since we found that Z to
E isomerization was rapid relative to cycloaddition, we have routinely used Z/E diene mixtures
and have never noted any effect on stereochemical outcomes of cycloadditon (when compared
to using pure E or Z dienes). We, therefore, used the E/Z mixture resulting from the preparation
shown here without any additional purification. Pyridine cobaloxime butadienyl complex
(5.1.1a) and pyridine cobaloxime pentadienyl complexes (5.1.1b, c) were prepared according to
the reported procedure.[56, 57, 59, 66-71]
25
Co(OAc)2.4H2O + (dmg) + Pya. Zn dust, THF, reflux (15min.)
b. 5.1.0a, ∆∆∆∆, 1 h
Me
Me
Co(dmg)2Py
5.1.1b, (47%, E-isomer)
Scheme - 5.1.1: Synthesis of cobaloxime dienes, 5.1.1a-e
CoCl2 + (dmg) + Pyr.t, 30 min.
ClCo(dmg)2PyClMg
Co(dmg)2Py
5.1.1a, 74%
5.1.0b
5.1.0a
MeC
OCO2Et
Co(OAc)2.4H2O + (R-glyoxime) + (L)a. Zn dust, THF, reflux (15min.)
b. 5.1.0b, ∆∆∆∆, 1 h
Me
Co(R-glyoxime)2(L)
E/ Z - isomer
5.1.1c, R = DMG; (L) = Py
5.1.1d, R = DMG; (L) = DMAP (68%, 2.3:1, Z:E)
5.1.1e, R = DPG; (L) = Py (89%, 1.5:1, Z:E)
5.2) Higher-Order [6+4] Cycloaddition Reactions of Cobaloxime Dienes with Tropones.
In a typical cycloaddition experiment, cobaloxime dienes were heated at various temperatures
in the presence of tropones (Scheme-5.2.1). The simplest tropone, cycloheptatrienone (5.2.1a)
reacted with a pyridine cobaloxime butadienyl complex (5.1.1a) and pyridine as well as DMAP
ligated cobaloxime pentadienyl complexes (5.1.1c and 5.1.1d). Those cycloaddition reactions
proceeded via [6+4] cycloaddition resulting in the formation of bicyclo[4.4.1]undecanones
(5.2.2a-c) in high yields. Cobaloxime substituted bicycloundecanones (5.2.2a-c) were formed as
single stereoisomers. NMR techniques such as 13C and HMBC were used to postulate the
regiochemistry [6+4 vs 4+2 cycloadduct] of the cycloadducts isolated. The [6+4] versus [4+2]
regiochemistry was supported initially by C=O 13C NMR resonances appearing in the 204-
209ppm range in all cases (5.2.2a-c) as well as HMBC cross peaks from both the CH2 and the RCH
26 protons to the C=O for 5.2.2b and 5.2.2c. That regiochemical postulate as well as
stereochemistry was subsequently confirmed by X-ray crystallography for complex 5.2.2b.
From the X-ray crystallographic data of cycloadduct 5.2.2b (Figure 5.2.1), the Co-carbon
bond in this complex is 1.976(6)Å and is similar to most of the other Cobalt-sp2 carbon bonds we
have reported in cobaloxime complexes previously.[66] The C(14)-Co-N(5) bond angle is very
close to 180o and the Co-C(14)-C(15) and Co-C(14)-C(20) bond angles are both very close to 120o
indicating that the complex has classical octahedral cobaloxime complex geometry and that
there is little if any steric interaction between the cobaloxime core and the bicyclic core of the
cycloadduct .
O R
Co(dmg)2(L)
O
H
HR
O R
Co(dmg)2(L)
(L)(dmg)2Co
++
5.2.1a [6+4] Cycloadduct (exo) [4+2] Cycloadduct
THF, ∆∆∆∆
12-24h
5.1.1a, R = H, (L) = Py 5.2.2a, R = H; L = Py (95%) 5.2.3a, not observed5.1.1c, R = Me, (L) = Py 5.2.2b, R = Me; L = Py (93%) 5.2.3b, not observed5.1.1d, R = Me, (L) = DMAP 5.2.2c, R = Me; L = DMAP (87%) 5.2.3c, not observed
Scheme - 5.2.1: [6+4] Cycloaddition reactions of tropone (5.2.1a) with cobaloxime dienes
27 The stereoisomers we isolated (5.2.2a-c) can be rationalized by an exo approach of the
tropone to the cobaloxime dienes (5.2.4) (Figure 5.2.2). This tropone approach would place the
reactive and sterically most cumbersome triene portion of the tropone away from the
cobaloxime diene substituent in the transition state. This is consistent with our stereochemical
observations of Diels-Alder reactions of these dienes.[58] The [6+4] cycloadduct yields and
stereochemistries obtained here compare favorably to those previously obtained with organic
dienes like 1,3-butadiene, trans-piperylene and isoprene which reacted with tropone in xylenes
in sealed tubes heated to 130oC to produce a 9:1 mixture of [6+4] : [4+2] products, a 60% yield
of [6+4] product, and an 86% yield of [6+4] product respectively.[29, 63]
We next investigated the cycloaddition chemistry (Scheme-5.2.3) of some simple
monosubstituted tropones with cobaloxime dienes. Specifically, we looked at reactions of both
2-methyl[72] (5.2.1b) and 2-phenyltropone[73] (5.2.1c). Substituents at the 2 and 7 positions of a
tropone (bond forming centers) would be expected to sterically retard the rates of [6+4]
cycloaddition and that trend is what we encountered here. Whereas tropone (5.2.1a) reacted
completely with all three cobaloxime dienes we tried in 12-24h, we found that 2-methyl (5.2.1b)
and 2-phenyltropone (5.2.1c) only produced cycloadducts (5.2.2d,e) in 44% and 26% yields
respectively after 72h of heating with diene (5.1.1c). At these long heating times significant
cobaloxime diene decomposition also starts to compete with cycloaddition. Interestingly, these
OO
LnCo
RR
LnCo
5.2.4
Figure 5.2.2: Exo approach of tropone to a cobalt substituted diene
28 tropones (5.2.1b, c) reacted with cobaloxime dienyl complex (5.1.1c) to produce a single
regio- and stereoisomer (5.2.2d, e).
The regio- and stereochemistries of these cycloadducts (5.2.2d, e) are postulated as shown
based on 1H and 13C NMR analogy to the cycloadduct 5.2.2b which we characterized by X-ray
crystallography. Proton and carbon resonances in the bicycloundecatrienone core for protons
and carbons other than the bridgehead carbon attached to R2 are almost identical when one
compares spectroscopic data for 5.2.2b to 5.2.2d or 5.2.2e. The methine proton alpha to R1 =
Me in both 5.2.2d and 5.2.2e shows coupling to only one alkene proton and the methyl group
(R1 = Me) as expected for the regiochemical outcome shown. In the case of 5.2.2d, it did not
prove possible to use NOESY (Nuclear Overhauser Enhancement Spectroscopy) to gain
additional stereochemical information about the relationship between R1 and R2. In 5.2.2d,
where both R1 and R2 are CH3 groups, their chemical shifts are too close together to permit
meaningful data to be gathered from NOESY. However, in the case of 5.2.2e (Figure-5.2.3),
where R1 = CH3 and R2 = Ph, the ortho protons on the benzene ring show NOESY cross peaks to
the protons on carbons 2, 9 and 12 but not to the methine proton on C10. The methine proton
on C10 shows strong NOESY cross peaks to both H2 and H3. This NMR data along with the
general spectroscopic similarities to 5.2.2b mentioned above lead us to postulate the
stereochemistry shown for 5.2.2d and 5.2.2e. Isolated yields of [6+4] cycloadducts (5.2.2d and
O R1
Co(dmg)2(DMAP)
O
H
R2
R1
(DMAP)(dmg)2Co
+
R2 = Me, 5.2.1b
= Ph, 5.2.1c
5.1.1c Exo [6+4]
THF, ∆∆∆∆
72 h
5.2.2d, R2 = Me, 44%
5.2.2e, R2 = Ph, 26% (37% based on
recovered starting material)
Scheme - 5.2.2: [6+4] Cycloaddition reactions of 2-substituted tropones with cobaloxime diene
2
3
4678
910
11
1 5
R2
29 5.2.2e) were modest however, [6+4] cycloadduct formation is known to be suppressed in
intermolecular cycloaddition reactions between 2-substituted tropones and organic rather than
organometallic1,3 dienes.[62, 74] This organometallic chemistry therefore provides access to
structural types which were not previously readily available.
We also note one unusual experimental observation from performing these reactions.
In the past, we had noted that we could synthesize stereochemically pure cobaloxime E-dienes
using reactions of cobaloxime anions with allenic electrophiles[70] or prepare E/Z mixtures using
the enyne hydrocobaltation procedure described earlier here. In Diels-Alder chemistry, we had
noted that Z-diene cycloadditions were much slower than Z:E isomerization and that
cycloaddition rates of E-dienes were fast relative to Z:E isomerization.[65] In these [6+4]
cycloadditions with 5.1.1d (R1 = Me, (L) = DMAP) and 5.2.1b (R2 = Me), we noted a difference
between using the Z/E mixture and stereochemically pure E. Whereas, diene 5.1.1b (pure E)
had reacted completely with 5.2.1b in 72h, the 5.1.1c (E/Z) mixture reaction was only ~50%
complete in that same time frame. The implication here is that [6+4] cycloaddition is slow
relative to Z:E isomerization.
5.3) [6+4] and [4+2] Cycloaddition Reactions of Cobaloxime Dienes with Substituted
Tropones. The cycloaddition chemistry of a number of tropones which were polysubstituted
[M]
H
Me
H
HOH
HNOE
NOE
NOE
[M]
H
Me
H
HNOE
Ph
O
H
H
H
NOE
NOENOE
Figure - 5.2.3: Schematic representation of NOE data for [6+4] cycloadduct, 5.2.2e
[M] = Co(dmg)2DMAP (other protons were not shown for clarity)
1
23
45
67
8
9
10
11
12
1
2
3
456
7
8
9
10
1112
13
14
15
16
14
15
30 and contained at least 1 electron withdrawing substituent (5.2.1d-g) were used with
cobaloxime dienes (5.1.1c) in order to see what effect this would have on the regio- and
stereochemical outcome of these cycloaddition reactions. In previously reported thermal
intermolecular cycloaddition reactions of unsymmetrical 1,3-dienes with 3- or 4-substituted
tropones, electron withdrawing substituents provided slightly higher yields of [6+4] products
than electron donating substituents, but product yields and regioisomer outcomes were modest
(10-20%) in both cases.10 Tropone (5.2.1d) which was unsubstituted at the 2nd & 6th positions,
but which also had an electron withdrawing group lead to the formation of two types of
cycloadducts (5.2.2f, 5.2.3a). In both cases a single stereo/regio isomer was isolated. Higher-
order [6+4] cycloaddition produced the minor isomer (5.2.2f) in this case whereas [4+2]
cycloaddition led to the major isomer (5.2.3a) in 1.0: 4.2 ratio (13%:55% isolated yields of
5.2.2f:5.2.3a). Once again this reaction of a cobaloxime substituted diene with a tropone
compared favorably with a reaction of an organic diene like isoprene with similar tropones
(Table-5.3.1, entries 2-4).10
31 Tropones (5.2.1h-l) that have substituents at the bond forming centers and EWG’s
inhibited the higher-order pathway. They reacted in [4+2] reaction pathways (Table-5.3.2) to
yield bicyclo[5.4.0]undecanones (5.2.3b-f). It should also be noted here that
tricarbonyl(tropone)iron has also previously been shown to contain a tropone core which
reacted with dienes in [4 +2] rather than [6 +4} cycloaddition reactions.[75] Presumably, in that
case, the Fe(CO)3 acts as an electron withdrawing group on 2 of the 3 alkene groups in the
tropone, leaving one of the alkene functional groups to react as a typical enone in Diels-Alder
chemistry.
The structure of cycloadduct 5.2.3b was confirmed by X-ray crystallography. The X-ray
crystallographic data of cycloadduct 5.2.3b (Figure 5.3.1) revealed a Co-carbon bond length of
1.987(6) Å in this complex. This and other cobalt coordination sphere bond lengths and angles
32 are similar to those which have have observed previously for complexes containing cobalt-sp
2
carbon bonds.[59]
The structures of cycloadducts 5.2.3c-f were inferred by analogy to the spectroscopic data of
5.2.3b and additional NMR data. With respect to the regiochemistry of cycloaddition in the case
of cycloadduct 5.2.3c, HMBC confirmed that the conjugated carbonyl carbon absorbing at
190ppm contained cross peaks only to the alkenyl proton R2 = H. Stereochemistry was inferred
by the strong NOESY cross peak between the ring junction proton (R4 = H) and the methyl group.
Likewise, for 5.2.3f, HMBC also confirmed that the conjugated carbonyl in that case showed
cross peaks only to the alkenyl protons R2 = R5 = H.
33
5.4) Demetallation of Tropone Cycloadducts. We have previously reported numerous
examples of the cleavage of cobaloxime-sp2 carbon bonds (Scheme-5.4.1) which yield
demetallated organic cycloadducts and a reusable cobaloxime complex.4 These cobaloxime
tropone cycloadducts also fall into this reaction category. When [6+4] adduct (5.2.2b) was
treated with trimethylaluminum, cycloadduct (5.4.1) was isolated in almost quantitative yield
along with pyr(dmg)2CoMe (5.4.2).
6.0) Conclusion. Cobaloxime dienyl complexes reacted with tropone and 2-methyl as well as
2-phenyltropone to produce [6+4] cycloadducts through exo transition states. When
cobaloxime dienyl complexes are treated with tropones which contain electron withdrawing
substituents then they participated in [4+2] cycloaddition reactions with the alkene in the
tropone that contained the electron withdrawing group. The [6+4] cycloadduct produced in one
case was removed from the cobaloxime core and recovered along with a cobaloxime methyl
complex which can be recycled back into the synthesis of the original dienyl complex.
5.2.2b 5.4.1 (96%) 5.4.2 (73%)
R2
O
H
HMe
O
H
H
Py(dmg)2CoAlMe3, THF
-15 °°°°C→→→→25 °°°°C
H
+ Py(dmg)2CoMe
Scheme - 5.4.1: Representative example for demetallation reaction of [6+4] cycloadduct
34
7.0) Experimental: General. The 1H NMR spectra were recorded by using a Bruker
Avance 500MHz spectrometer and Bruker Avance 300MHz spectrometer operating at
500.13MHz and 300.13MHz respectively. 13C NMR spectra were recorded on a Bruker Avance
300MHz spectrometer and Bruker Avance 500MHz spectrometer operating at 75.48MHz and
125.77MHz respectively. Chemical shifts were reported in parts per million (δ) relative to
tetramethylsilane (TMS), or the residual proton resonances in the deuterated solvents:
dimethylsulfoxide (DMSO,) or chloroform (CDCl3). Coupling constants (J values) were reported in
hertz (Hz), and spin multiplicities were indicated by the following symbols: s (singlet), d
(doublet), t (triplet), q (quartet), m (multiplet) and p (pentet).
All elemental analyses were carried out by Atlantic Microlabs Inc., GA. High resolution mass
spectrometric (HRMS) analyses were carried out at the Duke Mass Spectrometric Facility,
Durham, NC. Flash chromatography was performed using thick-walled glass chromatography
columns and “Ultrapure” silica gel (Silicycle Ind., Canada, 40 – 63 μm). Vacuum filtrations were
carried out with the aid of microanalysis vacuum filter apparatus and Millipore filter
membranes.
All reactions were carried out under an inert atmosphere unless otherwise noted.
Tetrahydrofuran, dimethylformamide and methylene chloride were purchased from Fischer
Scientific in the form of solvent kegs and distilled by using the centrally located solvent
dispensing system developed by J.C. Meyer.[76] Hexanes were distilled over CaH2 before use. Silyl
reagents were either purchased from Aldrich Chemicals or Gelest Inc. Deuterated solvents were
purchased from Cambridge Isotopes and used as received. All other chemicals were purchased
from Sigma-Aldrich and used as received. Pent-3-en-1-yne (5.1.0b),[77] ethyl penta-3,4-dien-2-yl
carbonate (5.1.0a),[17, 78-80] 2-methyltropone (5.2.1b, R2 = Me)[81], 2-phenyltropone (5.2.1c, R2 =
35 Ph)[82], 1,3-butadiene-2-yl-(pyridine)bis(dimethyl-glyoximato)cobalt(III) (5.1.1a),[83, 84] (3E)-1,3-
pentadien-2-yl-(pyridine)bis(dimethyl glyoximato) cobalt(III) (5.1.1b),[71] (3E)- and (3Z)-1,3-
pentadien-2-yl-(pyridine)bis(dimethyl glyoximato)cobalt(III) (5.1.1c),[71] were prepared according
to the reported literature. Other tropones (5.2.1d, h-l) were kindly donated by Dr. Huw M. L.
Davies & his research group at SUNY – Buffalo.
(3E)- and (3Z)-1,3-pentadien-2-yl-(4-(dimethylamino)pyridine)bis(dimethylglyoximatio)
Cobalt(III) (5.1.1d). A modification of a literature procedure was used to synthesize cobaloxime
diene (5.1.1d).[71] Cobalt(II) acetate tetrahydrate (2.452 g, 9.844
mmol) and dimethylglyoxime (2.275 g, 19.59 mmol) was dissolved in
degassed THF (100 mL). To this, 4-(dimethylamino)pyridine (1.808 g,
14.80 mmol), pre-dissolved in 5.00 mL of degassed THF and Zn dust
(3.194 g, 48.86mmol) was added successively. This mixture was refluxed for 15 min. The
reaction mixture was cooled enough to cease the reflux then 3-penten-1-yne (5.1.0b)[85] (0.972
g, 14.70 mmol) was added and the reflux was resumed for 1h. The reaction pot cooled to room
temperature and filtered using the celite pad (10 mm) to remove any insoluble materials. The
celite pad was washed with THF (3×10 mL) and the solvent removal results in the cobaloxime
complex deposition as yellowish-orange solid. The solid was vacuum dried and passed through
column (100 mm, EtOAc) to remove polar impurities affords (3.210 g, 6.709 mmol, 68%) of the
cobaloxime diene (5.1.1d) as an orange-yellow fluffy powder. The isomeric ratio (1.0:2.3 E to Z)
was determined by 1H NMR and the spectral data was identical to that reported earlier by our
group.[83, 84]
(3E)- and (3Z)-1,3-pentadien-2-yl-(pyridine)bis(diphenylglyoximato)cobalt(III) (5.1.1e).
Cobaloxime diene (5.1.1e) was prepared according to the procedure mentioned above except
Me
Co(DMG)2(DMAP)
(5.1.1d)
36 using pyridine and diphenylglyoxime in place of 4-(dimethylamino)pyridine and
dimethylglyoxime. Cobalt(II) acetate tetrahydrate (1.250 g, 5.018 mmol), diphenylglyoxime
(2.403 g, 10.0 mmol), freshly distilled pyridine (1.170 g, 14.79
mmol), Zn dust (3.194 g, 48.86mmol) and 3-penten-1-yne (5.1.0b)
(0.500 g, 7.560 mmol) were used. The resulting crude product was
purified by column chromatography (silica gel, 14.5 mm × 250 mm;
10 mm; EtOAc), which provided (3.386 g, 4.953 mmol, 89%) of the title compound (5.1.1e) as a
brown-yellow amorphous solid. The isomeric ratio (1.0:1.5 E to Z) was calculated based on 1H
NMR and the spectral data was identical to that reported earlier by our group.[83]
General Procedure for the Cycloaddition Reactions. A representative procedure follows: In a
sealed tube, cobalt substituted diene was dissolved in freshly distilled THF (7.0 mL) and purged
with nitrogen for few minutes. Tropone was added to the tube and heated in an oil bath at 110
˚C over a period of time. After completion of the reaction, the sealed tube was cooled to room
temperature and solvent was removed by rotary evaporation. Purification of the crude
compound by flash column chromatography using silica gel affords the cycloadduct in good to
moderate yields.
Higher-Order [6π + 4π] cycloaddition reactions.
Synthesis of ((1Hβ, 6Hβ)-bicyclo[4.4.1]undeca-2,4,8-trien-11-one-8-yl)pyridinebis(dimethyl
glyoximato)cobalt (5.2.2a): Diene (5.1.1a) (0.2 g, 0.475 mmol) and tropone (5.2.1a) (0.075 g,
0.712 mmol) were heated for 24 hours according to the general
procedure stated above. Removal of solvent and purification of the
product by flash chromatography affords cycloadduct (5.2.2a) (0.238 g,
4.52 mmol, 95%) as a yellow amorphous powder: mp (neat) 194 ˚C dec;
Rf 0.044 (pentane/ethyl acetate, 2:1); IR (CHCl3) υ 1562, 1449, 1089, 904, 703, 647 cm-1; 1H NMR
Me
Co(DPG)2(Py)
(5.1.1e)
O
H
H
(Py)(DMG)2Co
(5.2.2a)
37 (300 MHz, CDCl3) δ 8.63 (ad, J = 5.0 Hz, 2H), 7.70 (tt, J = 7.7, 1.3 Hz, 1H), 7.30 (t, J = 6.9 Hz,
2H), 5.72−5.78 (m, 2H, H−3, 4), 5.54−5.66 (m, 2H, H−9, 2/5), 5.43−5.52 (m, 1H, H−2/5),
3.05−3.21 (m, 2H, H−1, 6), 2.80 (dd, J = 14.9, 8.9 Hz, 1H, H−10), 2.41−2.52 (m, 1H, H−7),
2.24−2.33 (m, 1H, H−7), 2.15 (s, 6H), 2.04 (s, 6H), 2.03−2.03 (m, 1H, H−10); 13C NMR (75.5 MHz,
CDCl3) δ 208.8 (C−11), 149.9 (CH), 137.3 (CH), 130.0 (C−9), 129.0 (C−2), 128.5 (C−5), 125.0 (CH),
123.9 (C−3/4), 121.8 (C−3/4), 56.6 (C−6), 55.8 (C−1), 36.2 (C−10), 30.4 (C−7), 12.1 (CH3), 11.9
(CH3); Anal. calcd for C24H30CoN5O5: C, 54.65; H, 5.73. Found: C, 54.42; H, 5.75.
Synthesis of (7α-Methyl-(1Hβ, 6Hβ)-bicyclo[4.4.1]undeca-2,4,8-trien-11-one-9-yl)pyridinebis-
(dimethylglyoximato)cobalt (5.2.2b): Diene (5.1.1c) (0.100 g, 0.230 mmol) and tropone (5.2.1a)
(0.037 g, 0.344 mmol) were heated for 16 hours according to the general
procedure. After heating the solvent was reduced and the compound was
purified by flash chromatography to yield cycloadduct (5.2.2b) (0.115 g,
0.212 mmol, 93%) as a yellowish brown powder: mp (neat) 210 ˚C dec; Rf
0.195 (pentane/ethyl acetate, 2:3); IR (CHCl3) υ 1562, 1449, 1089, 902, 726, 703, 648 cm-1; 1H
NMR (300 MHz, CDCl3) δ 8.63 (dt, J = 5.0, 1.3 Hz, 2H), 7.70 (tt, J = 7.7, 1.3 Hz, 1H), 7.30 (at, J = 6.9
Hz, 2H), 5.75−5.83 (m, 2H, H−3, 4), 5.67−5.75 (m, 1H, H−5), 5.39−5.47 (m, 1H, H−2), 5.31 (bs, 1H,
H−8), 3.05−3.15 (m, 1H, H−1), 2.88 (dd, J = 14.8, 9.3 Hz, 1H, H−10), 2.64−2.77 (m, 2H, H−6, 7),
2.15 (s, 6H), 2.09 (s, 6H), 1.97 (ddd, J = 15.4, 9.3, 2.4 Hz, 1H, H−10), 1.07 (d, J = 6.09 Hz, 3H,
H−12); 13C NMR (75.5 MHz, CDCl3) δ 208.7 (C−11), 150.9 (C), 150.5 (C), 150.2 (CH), 138.9 (C−8),
137.5 (CH), 129.3 (C−2), 127.8 (C−5), 125.2 (CH), 124.5 (C−4), 121.7 (C−3), 64.5 (C−6), 55.4 (C−1),
37.1 (C−10), 36.8 (C−7), 19.3 (C−12), 12.3 (CH3), 12.1 (CH3); HRMS calcd for C25H32CoN5O5 (M+)
541.1735, found 541.1727. Anal. calcd for C25H32CoN5O5: C, 55.44; H, 5.96. Found: C, 55.04; H,
5.99.
O
H
H
(Py)(DMG)2Co
(5.2.2b)
Me
38 Synthesis of (7α-Methyl-(1Hβ, 6Hβ)-bicyclo[4.4.1]undeca-2,4,8-trien-11-one-9-yl)(4’-N,N-
dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.2c): Diene (5.1.1d) (0.200 g, 0.418
mmol) and tropone (5.2.1a) (0.067 g, 0.631 mmol) were heated for
12 hours according to the general procedure. The solvent was
removed and the compound was crystallized using a dual solvent
technique where the product was first dissolved in hot
dichloroethane followed by the addition of cyclohexane at room temperature, which afforded
cycloadduct (5.2.2c) (0.212 g, 0.363 mmol, 87%) as brown crystalline material: mp (neat) 240 ˚C
dec; IR (CHCl3) υ 1620, 1388, 1089, 905, 760, 739, 705, 649 cm-1; 1H NMR (300 MHz, CDCl3) δ
8.09 (d, J = 6.9 Hz, 2H), 6.40 (t, J = 6.9 Hz, 2H), 5.73−5.83 (m, 2H, H−3, 4), 5.65−5.73 (m, 1H, H−5),
5.42 (dd, J = 12.4, 6.2 Hz, 1H, H−2), 5.33 (bs, 1H, H−8), 3.04−3.17 (m, 1H, H−1), 2.96 (s, 6H),
2.84−2.93 (m, 1H, H−10), 2.62−2.75 (m, 2H, H−6, 7), 2.14 (s, 6H), 2.09 (s, 6H), 1.91−2.03 (m, 1H,
H−10), 1.06 (d, J = 5.7 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ 208.8 (C−11), 154.2 (C), 150.2
(C), 149.8 (C), 149.0 (CH), 138.7 (C−8), 129.5 (C−2), 127.9 (C−5), 124.4 (C−4), 121.5 (C−3), 107.5
(CH), 64.6 (C−6), 55.6 (C−1), 39.0 (CH3), 37.1 (C−10), 36.7 (C−7), 19.4 (C−12), 12.2 (CH3), 12.0
(CH3); Anal. calcd for C27H37CoN6O5: C, 55.46; H, 6.38. Found: C, 55.76; H, 6.42.
Synthesis of (10α-Methyl-(1β-methyl, 6Hβ)-bicyclo[4.4.1]undeca-2,4,8-trien-11-one-8-yl)(4’-
N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.2d): Diene (5.1.1d) (0.100 g,
0.209 mmol), tropone (5.2.1b, R2 = Me) (0.050 g, 0.418 mmol) were
heated for 72 hours according to the general procedure. Purification of
the compound by column chromatography yielded cycloadduct
(5.2.2d) (0.055g, 0.092 mmol, 44%) as a yellow amorphous material.:
mp (neat) 154 ˚C decompose; Rf 0.189 (diethyl ether/hexane, 3:2); 1H NMR (300 MHz, CDCl3) δ
8.09 (d, J = 7.2 Hz, 2H), 6.39 (d, J = 7.2 Hz, 2H), 5.77 (dd, J = 11.7, 7.2 Hz, 1H, H−4), 5.71 (dd, J =
O
H
H
(DMAP)(DMG)2Co
(5.2.2c)
Me
O
H
Me
(DMAP)(DMG)2Co
(5.2.2d)
Me
39 11.7, 7.2 Hz, 1H, H−3), 5.25−5.39 (m, 3H, H−2, 5, 9), 3.30−3.42 (m, 1H, H−6), 2.91−3.09 (m, 2H,
H−7, 10), 2.96 (s, 6H), 2.14 (s, 6H), 2.08 (s, 6H), 1.91−2.01 (m, 1H, H−7), 1.01 (s, 3H, H−13), 0.96
(d, J = 6.8 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ 209.2 (C−11), 154.2 (C), 150.2 (C), 149.8
(C), 149.1 (CH), 138.5 (C−9), 135.1 (C−2), 130.8 (C−5), 123.7 (C−3), 120.7 (C−4), 107.5 (CH), 60.8
(C−1), 54.9 (C−6), 39.0 (CH), 37.1 (C−10), 37.0 (C−7), 18.5 (C−13), 15.3 (C−12), 12.1 (CH3), 11.9
(CH3); HRMS calcd for C28H40CoN6O5 (M + H)+ 599.2392, found: 599.2399.
Synthesis of (10α-Phenyl-(1β-methyl, 6Hβ)-bicyclo[4.4.1]undeca-2,4,8-trien-11-one-8-yl)(4’-
N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.2e): Diene (5.1.1d) (0.200 g,
0.418 mmol) and tropone (5.2.1c, R2 = Ph) (0.138 g, 0.758 mmol)
were heated for 72 hours according to the general procedure. Initial
chromatographic separation of the crude product yielded excess
tropone (5.2.1c, R2 = Ph) (0.084 g, 0.462 mmol, 61%) followed by the
cycloadduct (5.2.2e) and unreacted diene (5.1.1d) as a dark yellow mixture (0.119 g). Rf 0.64
(100% diethyl ether); Further purification of the cobaloxime mixture by another column
chromatography yielded the pure cycloadduct (5.2.2e) (0.073 g, 0.111 mmol, 26%) as yellow
powder: mp (neat) 156−159 ºC ; Rf 0.16 (hexanes/diethyl ether, 4:1); 1H NMR (500 MHz, CDCl3) δ
8.13 (d, J = 6.6 Hz, 2H), 7.29−7.36 (m, 2H, H−15), 7.18−7.24 (m, 3H, H−14, 16), 6.42 (d, J = 6.6 Hz,
2H), 6.05 (d, J = 12.1 Hz, 1H, H−2), 5.90 (dd, J = 12.1, 7.6 Hz, 1H, H−3), 5.81 (dd, J = 11.3, 7.6 Hz,
1H, H-4), 5.68 (dd, J = 11.3, 7.1 Hz, 1H, H−5), 5.63 (d, J = 7.6 Hz, 1H, H−9), 3.40 (p, J = 7.1 Hz, 1H,
H−10), 3.13−3.25 (m, 1H, H−6), 2.90−3.06 (m, 1H, H−7), 2.98 (s, 6H), 2.13−2.20 (m, 1H, H−7),
2.11 (s, 6H), 2.02 (s, 6H), 0.81 (d, J = 7.1 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ 207.9
(C−11), 154.2 (C), 150.2 (C), 149.9 (C), 149.0 (CH) 141.2 (C−13), 132.1 (C−2), 131.2 (C−5), 130.2
(C−15), 127.4 (C−14), 126.1 (C−16), 122.3 (C−3), 121.3 (C−4), 107.5 (CH), 71.5 (C−1), 55.2 (C−6),
O
H
Ph
(DMAP)(DMG)2Co
(5.2.2e)
Me
40 42.6 (C−10), 39.0 (CH3), 37.5 (C−7), 16.2 (C−12), 12.2 (CH3), 12.0 (CH3); HRMS calcd for
C33H42CoN6O5 (M + H)+ 661.2548, found: 661.2542.
Synthesis of (7α-Methyl-(1Hβ, 6Hβ)-5-carbomethoxy-2-methoxy-3-phenyl-bicyclo[4.4.1]
undeca-2,4,8-trien-11-one-9-yl)pyridinebis(dimethylglyoximato)cobalt (5.2.2f) and (1β-carbo-
methoxy,7Hβ,11β-methyl)-4-methoxy-
3-phenyl-bicyclo[5.4.0]undeca-2,4,9-
trien-6-one-9-yl)
pyridinebis(dimethylglyoximato)cobalt
(5.2.3a): Diene (5.1.1d) (0.033 g, 0.078 mmol) and tropone (5.2.1d) (0.021 g, 0.078 mmol) were
heated for 25 hours according to the general procedure mentioned above. The compound was
purified by flash chromatography which afforded cycloadducts (5.2.2f, 5.2.3a) (0.036 g, 0.051
mmol, 68%): Cycloadduct–5.2.2f: amorphous blackish-green solid (0.008g, 0.011 mmol, 15%): Rf
0.234 (diethyl ether/pentane, 3:2); 1H NMR (500 MHz, CDCl3) δ 8.64 (d, J = 5.1 Hz, 2H), 7.71 (at, J
= 7.6 Hz, 1H), 7.27−7.34 (m, 4H), 7.15− 7.24 (m, 4H), 5.34 (ad, J = 6.2 Hz, 1H, H−8), 3.79 (s, 3H,
H−15), 3.57 (at, J = 9.0 Hz, 1H, H−1), 3.39 (s, 3H, H−14), 3.15−3.25 (m, 1H, H−10), 2.97−3.10 (m,
2H, H−6,7), 2.18 (s, 6H), 2.12 (s, 6H), 1.94−1.99 (m, 1H, H−10), 1.19 (d, J = 6.2 Hz, 3H, H−12); 13C
NMR (75.5 MHz, CDCl3) δ 206.4 (C−11), 166.9 (C−2), 158.7 (C−13), 150.8 (C), 150.3 (C), 150.2
(CH), 141.0 (C), 137.9 (C−8), 137.5 (CH), 135.4 (C−4), 129.1 (CH), 128.1 (CH), 126.6 (CH), 125.2
(CH), 125.1 (C−2), 119.5 (C−5), 63.9 (C−6), 52.1 (C−1), 37.3 (C−10), 36.3 (C−7), 19.4 (C−12), 12.3
(CH3), 12.1 (CH3); HRMS calcd for C34H40CoN5O8 (M)+ 705.2209, found 705.2202. Cycloadduct–
5.2.3a: amorphous yellow-brown solid (0.028g, 0.04 mmol, 53%): mp (neat) 209−211 ˚C
decomposes; Rf 0.328 (diethyl ether/pentane, 3:2); 1H NMR (500 MHz, TMS) δ 8.47 (d, J = 5.2 Hz,
2H), 7.59 (at, J = 7.6 Hz, 1H), 7.03−7.32 (m, 7H), 5.79 (s, 1H, H−2), 5.52 (s, 1H, H−5), 5.15 (d, J =
5.5 Hz, 1H, H−10), 3.54 (s, 3H, H−14), 3.48 (s, 3H, H−15), 3.03 (dd, J = 12.3, 5.5 Hz, 1H, H−7), 2.51
O
(DMAP)(DMG)2Co
(5.2.2f)[6+4] adduct
Me O
Co(DMG)2(DMAP)
MeO2C
H
MePh
MeO
CO2Me
PhOMe
(5.2.3a)[4+2] adduct
41 (p, J = 6.3 Hz, 1H, H−11), 2.27−2.36 (m, 1H, H−8), 1.85−1.95 (m, 1H, H−8), 1.72 (s, 6H), 1. 70 (s,
6H), 0.72 (d, J = 6.8 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ 200.8 (C−6), 173.8 (C−13), 163.3
(C−4), 150.0 (CH), 149.7 (C), 140.4 (C−2), 139.6 (C), 137.7 (C−3), 137.5 (CH), 128.0 (CH), 127.9
(CH), 127.5 (C−10), 127.3 (CH), 125.1 (CH), 106.9 (C−5), 55.4 (C−15), 51.8 (C−14), 51.2 (C−7), 50.5
(C−1), 43.0 (C−11), 32.9 (C−8), 17.7 (C−12), 11.8 (CH3); HRMS calcd for C34H41CoN5O8 (M+H)+
706.2287, found 706.2283.
Diels-Alder [4+2] cycloaddition reactions.
Synthesis of (1β,3-dicarboethoxy-7Hβ,11β-methyl)-5-methoxy-bicyclo[5.4.0]undeca-2,5,9-
trien-4-one-9-yl)(4’-N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.3b): Diene
(5.1.1d) (0.074 g, 0.155 mmol) and tropone (5.2.1h) (0.064 g,
0.228 mmol) were heated for 36 hours according to the general
procedure mentioned above. The compound was purified by
flash chromatography to afford cycloadduct (5.2.3b) (0.078 g, 0.103 mmol, 67%) as a yellowish-
brown powder. The product was further purified by dual solvent recrystallization using ethyl
acetate to dissolve the compound and the cyclohexane for slow diffusion: mp (neat) 134−136 ˚C;
Rf 0.133 (ethyl acetate/hexane, 3:1); 1H NMR (500 MHz, CDCl3) δ 8.04 (d, J = 7.1 Hz, 2H), 6.64
(bs, 1H, H−2), 6.38 (d, J = 7.1 Hz, 2H), 5.87 (d, J = 8.7 Hz, 1H, H−6), 5.32 (bd, J = 5.5 Hz, 1H, H−10),
4.17−4.25 (m, 1H, H−17), 4.09−4.17 (m, 1H, H−17), 3.94−4.06 (m, 2H, H−14), 3.56 (s, 3H, H−19),
2.95 (s, 6H), 2.85−2.92 (m, 1H, H−7), 2.47−2.60 (m, 2H, H−8, 11), 2.08 (s, 6H), 2.03 (s, 6H),
1.62−1.72 (dd, J = 18.5, 11.2Hz, 1H, H−8), 1.27 (t, J = 7.1 Hz, 3H, H−18), 1.11 (t, J = 7.1 Hz, 3H,
H−15), 0.76 (d, J = 6.8 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ 184.7 (C−4), 171.8 (C−13),
165.8 (C−16), 154.2 (C), 150.9 (C−5), 149.7 (C−9), 149.1 (C−1), 148.9 (CH), 148.7 (C−2), 135.3
(C−3), 127.0 (C−10), 119.1 (C−6), 107.5 (CH), 61.2 (C−17), 60.9 (C−14), 55.4 (C−19), 53.3 (C), 42.4
EtO2C
H
MeEtO2C
O
Co(DMG)2DMAPMeO
(5.2.3b)
42 (C−11), 39.0 (CH3), 37.0 (C−8), 33.9 (C−7), 18.0 (C−12), 14.06 & 14.00 (C−15, 18), 11.92, &
11.89 (dmg CH3’s); HRMS calcd for C34H47CoN6O10 (M+H)+ 759.2764, found 759.2762.
Synthesis of (1β-carbomethoxy,7Hβ,11β-methyl)-6-methoxy-3-phenyl-bicyclo[5.4.0]undeca-
2,5,9-trien-4-one-9-yl)(4’-N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.3c)
Diene (5.1.1d) (0.060 g, 0.125 mmol) and tropone (5.2.1i) (0.050
g, 0.185 mmol) were heated for 22 hours according to the general
procedure mentioned above. The compound was purified by flash
chromatography to yield cycloadduct (5.2.3c) (0.035 g, 0.047 mmol, 38%) as an amorphous
brown powder: mp (neat) 205−207 ˚C decomposes; Rf 0.326 (ethyl acetate); 1H NMR (500 MHz,
CDCl3) δ 8.00 (d, J = 7.0 Hz, 2H), 7.34−7.11 (m, 5H), 6.35 (d, J = 7.0 Hz, 2H), 6.00 (s, 1H, H−2), 5.45
(s, 1H, H−5), 5.27 (d, J = 5.5 Hz, 1H, H−10), 3.70 (s, 3H, H−15), 3.58 (s, 3H, H−14), 2.93 (s, 6H),
2.83 (dd, J = 8.6, 5.2 Hz, 1H, H−7), 2.59 (dd, J = 11.9, 5.5 Hz, 1H, H−8), 2.48-2.56 (m, 1H, H−11),
1.93−2.03 (m, 1H, H−8), 1.86 (s, 6H), 1.79 (s, 6H), 0.76 (d, J = 7.0 Hz, 3H, H−12); 13C NMR (75.5
MHz, CDCl3) δ 189.1 (C−4), 179.0 (C−6), 173.5 (C−13), 154.1 (C), 149.3 (C), 149.1 (C), 148.8 (CH),
142.5 (C−3), 140.3 (C−2), 140.2 (C), 128.5 (CH), 127.8 (CH), 127.1 (CH), 126.9 (C−10), 107.4 (CH),
104.2 (C−5), 56.0 (C−15), 51.9 (C−14), 51.6 (C−1), 43.3 (C−11), 41.9 (C−7), 38.9 (CH3), 35.5 (C−8),
17.9 (C−12), 11.9 (CH3), 11.6 (CH3); HRMS calcd for C36H45CoN6O8 (M + H)+ 749.2709, found
749.2709.
Synthesis of (1β-carbomethoxy,7Hβ,11β-methyl)-3-methyl-6-methoxy-bicyclo[5.4.0]undeca-
2,5,9-trien-4-one-9-yl)(4’-N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.3d)
Diene (5.1.1d) (0.015 g, 0.032 mmol) and tropone (5.2.2j) (0.008 g, 0.038 mmol) were heated for
23 hours according to the general procedure mentioned above. The compound was purified by
flash chromatography to afford cycloadduct (5.2.3d) (0.010 g, 0.015 mmol, 46%) as brown
MeO2C
H
MePh
O
Co(DMG)2DMAP
(5.2.3c)
OMe
43 powdery material: mp (neat) 149 ˚C dec; Rf 0.310 (ethylacetate/hexane, 3:1); 1H NMR (500
MHz, CDCl3) δ 8.06 (d, J = 7.2 Hz, 2H), 6.39 (d, J = 7.2 Hz, 2H), 5.75 (s, 1H, H−2), 5.30 (s, 1H, H−5),
5.27 (d, J = 5.4 Hz, 1H, H−10), 3.66 (s, 3H, H−16), 3.57 (s, 3H,
H−14), 2.96 (s, 6H), 2.73 (add, J = 11.4, 5.4 Hz, 1H, H−7), 2.51 (dd,
J = 18.0, 5.4 Hz, 1H, H−8), 2.39−2.46 (m, 1H, H−11), 2.09 (s, 6H),
2.04 (s, 6H), 1.86 (dd, J = 18.0, 11.4 Hz, 1H, H−8), 1.78 (s, 3H, H−15), 0.72 (d, J = 6.9 Hz, 3H,
H−12); 13C NMR (75.5 MHz, CDCl3) δ 189.4 (C−4), 178.5 (C−6), 173.6 (C−13), 154.2 (C), 149.3 (C),
148.9 (CH), 148.8 (C), 139.7 (C−2), 127.0 (C−10), 107.5 (CH), 103.3 (C−5), 55.9 (C−16), 51.8
(C−14), 43.6 (C−11), 41.5 (C−7), 39.0 (CH3), 36.1 (C−8), 20.7 (C−15), 18.0 (C−12), 12.0 (CH3);
HRMS calcd for C31H43CoN6O8 (M + H)+ 687.2552, found 687.2556.
Synthesis of (1β-carbomethoxy,7Hβ,11β-methyl)-6-methoxy-3-thioethyl-bicyclo[5.4.0]undeca-
2,5,9-trien-4-one-9-yl)(4’-N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.3e)
Diene (5.1.1d) (0.066 g, 0.138 mmol) and tropone (5.2.2k)
(0.070 g, 0.275 mmol) were heated for 40 hours according to
the general procedure mentioned above. The compound was
purified by flash chromatography which afforded cycloadduct (5.2.3e) (0.087 g, 0.119 mmol, 87
%) as yellowish-brown powdery material: mp (neat) 183 ˚C dec; Rf 0.367 (diethyl ether); 1H NMR
(500 MHz, CDCl3) δ 8.05 (d, J = 6.0 Hz, 2H), 6.39 (d, J = 6.0 Hz, 2H), 5.59 (s, 1H, H−2), 5.37 (s, 1H,
H−5), 5.24 (d, J = 5.7 Hz, 1H, H−10), 3.68 (s, 3H, H−17), 3.57 (d, J = 1.3 Hz, 3H, H−14), 2.96 (d, J =
1.1 Hz, 6H), 2.75 (dd, J = 11.7, 5.4 Hz, 1H, H−7), 2.54−2.63 (m, 2H, H−8, 15), 2.42−2.63 (m, 2H,
H−11, 15), 2.09 (d, J = 1.1 Hz, 6H), 2.06 (d, J = 1.1 Hz, 6H), 1.86 (dd, J = 18.0, 11.7 Hz, 1H, H−8),
1.26 (t, J = 7.4 Hz, 3H, H−16), 0.73 (d, J = 6.8 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ 185.7
(C−4), 179.1 (C−6), 173.1 (C−13), 154.2 (C), 149.8 (C), 148.9 (CH), 148.8 (C), 138.2 (C−3), 136.0
(C−2), 127.0 (C−10), 107.5 (CH), 102.5 (C−5), 56.2 (C−17), 52.2 (C−1), 51.9 (C−14), 43.8 (C−11),
MeO2C
H
MeMe
O
Co(DMG)2DMAP
(5.2.3d)
OMe
MeO2C
H
MeSEt
O
Co(DMG)2DMAP
(5.2.3e)
OMe
44 41.7 (C−7), 39.0 (CH3), 36.0 (C−8), 25.9 (C−15), 18.2 (C−12), 12.9 (C−16), 12.1 (CH3), 12.0 (CH3);
Anal. calcd for C32H45CoN6O8S: C, 52.44; H, 6.19. Found: C, 52.48; H, 6.52.
Synthesis of (1β-carbomethoxy,7Hβ,11β-methyl)-5-methoxy-3-phenyl-bicyclo[5.4.0]undeca-
2,5,9-trien-4-one-9-yl)(4’-N,N-dimethylamino)pyridinebis(dimethylglyoximato)cobalt (5.2.3f)
Diene (5.1.1d) (0.047 g, 0.01 mmol) and tropone (5.2.2l) (0.032
g, 0.118 mmol) were heated for 36 hours according to the
general procedure mentioned above. The compound was
purified by flash chromatography to yield cycloadduct (5.2.3f) (0.019 g, 0.024 mmol, 29%) as an
amorphous yellow powder: mp (neat) 156 ˚C dec; Rf 0.204 (diethyl ether/hexane, 4:1); 1H NMR
(500 MHz, CDCl3) δ 8.03 (d, J = 6.3 Hz, 2H), 7.05−7.32 (m, 5H), 6.37 (d, J = 6.3 Hz, 2H), 6.11 (s, 1H,
H−2), 5.96 (d, J = 8.6 Hz, 1H, H−6), 5.28 (ad, J = 5.5 Hz, 1H, H−10), 3.61 (s, 3H, H−15), 3.57 (s, 3H,
H−14), 2.94 (s, 6H), 2.86−3.01 (m, 1H, H−7), 2.50−2.63 (m, 2H, H−8,11), 1.89 (s, 6H), 1.87 (s, 6H),
1.75 (dd, J = 17.3, 11.4 Hz, 1H, H−8), 0.77 (d, J = 6.7 Hz, 3H, H−12); 13C NMR (75.5 MHz, CDCl3) δ
188.1 (C−4), 173.4 (C), 154.2 (C), 151.7 (C), 149.6 (C), 148.9 (CH), 142.4 (C−2), 142.0 (C), 140.0
(C), 128.6 (CH), 127.9 (CH), 127.4 (CH), 127.1 (C−10), 119.3 (C−6), 107.5 (CH), 55.5 (C−15), 53.7
(C−8), 51.9 (C−14), 43.3 (C−11), 39.0 (CH3), 37.2 (C-8), 33.8 (C−7), 18.3 (C−12), 11.9 (CH3), 11.7
(CH3); HRMS calcd for C36H45CoN6O8 (M + H)+ 749.2709, found 749.2709.
Demetallation reaction of the cycloadduct (5.2.2b) using trimethyl aluminum:[86] Cycloadduct
(5.2.2b) (0.300 g, 0.554 mmol) was dissolved in distilled THF (10 mL) in a flame dried 2-neck
round bottom flask fitted with a nitrogen inlet. This contents were cooled to -15˚ C
using an ethylene/glycol ice bath. Trimethylaluminum (850 μL of a 2.0M solution
in hexanes, 1.66 mmol) was added in ca. 5 min. The solution was warmed to room
temperature over in 30 min and stirring continued for 2 h. Ice water (10 mL) was
added and the mixture was extracted with dichloromethane (4×10 mL). The organics were
MeO2C
H
MePh
O
Co(DMG)2DMAP
(5.2.3f)
MeO
O
H
H
(5.4.1)
Me
45 combined, dried over MgSO4 and the solvent was removed by rotary evaporation. The
demetallated cycloadduct was purified by column chromatography to yield cycloadduct (5.4.1)
(0.092 g, 0.528 mmol, 96%) as colorless oil: Rf 0.86 (ethyl acetate/pentane, 1:1). The spectral
data of the product was correlated with the reported literature values.[41] Further elution also
yielded cobalt complex (5.4.2) (0.155g, 0.405 mmol, 73%).
X-Ray Experimental Information for C25 H32CoN5O5 (5.2.2b). Several weakly-diffracting crystals
of 5.2.2b were examined before selecting an orange-brown parallelepiped-shaped crystal of
approximate dimensions 0.46 mm x 0.26 mm x 0.10 mm for the X-ray crystallographic analysis. A
full hemisphere of diffracted intensities (omega scan width of 0.30°) was measured using graphite-
monochromated MoKα radiation on a Bruker SMART APEX CCD Single Crystal Diffraction System.
X-rays were provided by a fine-focus sealed x-ray tube operated at 50kV and 30mA.
The frames were integrated with the Bruker SAINT Software package using a narrow-frame
integration algorithm. Integration of the dataset used a monoclinic unit cell and yielded a total
of 16838 reflections to a maximum 2θ angle of 48.3° (4067 were independent, Rint = 0.112). The
final cell constants of a = 8.173(3) Å, b = 22.819(8) Å, c = 13.929(5) Å, β = 99.147(5)°, V =
2565(2)Å3, are based upon the refinement of the XYZ-centroids of 1575 reflections with
8.23°<2Θ<36.32°. Analysis of the data showed negligible decay during data collection.
The structure was solved using "Direct Methods" techniques with the Bruker AXS SHELXTL (vers
6.12) software package. All stages of weighted full-matrix least-squares refinement were conducted
using Fo2 data. The structure was initially solved and refined in the centrosymmetric space group
P21/n since the statistics and systematically absent reflections for the intensity data indicated this
was the correct choice. When the resulting structural model contained anomalous metrical
parameters, the structure was solved and refined again in the noncentrosymmetric space groups
46 P21 and Pn. These refinements also considered the possibility of merohedral twinning. Neither of
the models from these noncentrosymmetric refinements resulted in metrical parameters superior
to those obtained from the initial centrosymmetric refinement; furthermore, the anisotropic
thermal parameters for several nonhydrogen atoms also refined to non-positive-definite values.
The final structure refinement was therefore performed in the centrosymmetric P21/n description.
This refinement converged to: R1 (unweighted, based on F) = 0.068 for 2208 independent
reflections having 2Θ(MoKα ) < 48.3o and F2>2σ(F2); R1 (unweighted, based on F) = 0.124 and wR2
(weighted, based on F2) = 0.159 for all 4067 reflections. The goodness-of-fit was 0.901 . The largest
peak in the final difference Fourier map was 0.83 e-/Å3 and the largest hole was -0.45 e-/Å3.
The final structural model incorporated anisotropic thermal parameters for all nonhydrogen
atoms and isotropic thermal parameters for all hydrogen atoms. Hydroxyl hydrogen atoms of the
DMG ligands were located from a difference Fourier map and refined as independent isotropic
atoms. The methyl groups were refined as rigid rotors (using idealized sp3-hybridized geometry and
a C-H bond length of 0.98Å). The remaining hydrogen atoms were included in the structural model
as fixed atoms (using idealized sp2- or sp3-hybridized geometry and C-H bond lengths of 0.95-1.00 Å)
"riding" on their respective carbon atoms. The isotropic thermal parameters for hydroxyl hydrogen
atoms were fixed at values 1.2 times the equivalent isotropic thermal parameter of the oxygen
atom to which they are covalently bonded. The isotropic thermal parameter of each remaining
hydrogen atom was fixed at a value 1.2 (nonmethyl) or 1.5 (methyl) times the equivalent isotropic
thermal parameter of the carbon atom to which it is covalently bonded. On the basis of the final
model, the calculated density was 1.402 g/cm3 and F(000), 1136 e-.
All calculations were performed using the SHELXTL (Version 6.12) interactive software package
(Bruker (2001). SHELXTL-NT (Version 6.12). Bruker AXS Inc., Madison, Wisconsin, USA).
47 X-Ray Experimental Information for Co(C4H7N2O2)2(C7H10N2)(C19H23O6) (5.2.3b). Single crystals
of 5.2.3b are, at 193(2)oK, orthorhombic, space group Pna21 – C 9
2v (No. 33) with a = 9.199(1) Å, b =
29.552(4) Å, c = 14.318(2) Å, V = 3892.5(9))Å3, and Z = 4 formula units I. A yellow crystal of
approximate dimensions 0.22 x 0.19 x 0.04 mm was used for the X-ray crystallographic analysis. A
full hemisphere of diffracted intensities (omega scan width of 0.30°) was measured using graphite-
monochromated MoKα radiation on a Bruker SMART APEX CCD Single Crystal Diffraction System.
X-rays were provided by a fine-focus sealed x-ray tube operated at 50kV and 30mA.
Lattice constants were determined with the Bruker SMART software package (SMART version
5.628 and SAINT version 6.36a, Bruker AXS Inc., Madison, Wisconsin, USA.) using peak centers for
2693 reflections with 7.63°<2Θ<35.65°. A total of 24196 integrated intensities were produced using
the Bruker program SAINT, of which 6189 were independent and gave Rint = 0.082. Analysis of the
data showed negligible decay during data collection. Data were corrected for absorption effects
using the multi-scan technique (SADABS).
The structure was solved using "Direct Methods" techniques with the Bruker AXS SHELXTL (vers
6.12) software package. All stages of weighted full-matrix least-squares refinement were conducted
using Fo2 data and converged to give R1 (unweighted, based on F) = 0.079 for 5162 independent
reflections having 2Θ(MoKα ) < 48.3o and F2>2σ(F2);. The goodness-of-fit was 1.204. The largest
peak in the final difference Fourier map was 0.68 e-/Å3 and the largest hole was -0.54 e-/Å3. The
Flack parameter refined to a final value of 0.03(3).
The structural model incorporated anisotropic thermal parameters for all nonhydrogen atoms
and isotropic thermal parameters for all hydrogen atoms. Hydroxyl hydrogen atoms of the DMG
ligands were located from a difference Fourier map and refined as independent isotropic atoms.
The methyl groups were refined as rigid rotors (using idealized sp3-hybridized geometry and a C-H
48 bond length of 0.98Å). The remaining hydrogen atoms were included in the structural model as
fixed atoms (using idealized sp2- or sp3-hybridized geometry and C-H bond lengths of 0.95-1.00 Å)
"riding" on their respective carbon atoms. The isotropic thermal parameters for hydroxyl hydrogen
atoms refined to final values of 0.04(2)Å2. The isotropic thermal parameter of each remaining
hydrogen atom was fixed at a value 1.2 (nonmethyl) or 1.5 (methyl) times the equivalent isotropic
thermal parameter of the carbon atom to which it is covalently bonded.
All calculations were performed using the SHELXTL (Version 6.12) interactive software package
(Bruker (2001). SHELXTL-NT (Version 6.12). Bruker AXS Inc., Madison, Wisconsin, USA).
49
CHAPTER 3 SYNTHESIS OF NOVEL 2-SILYL SUBSTITUTED-1, 3-DIENYL COMPOUNDS
AND THEIR DOMINO REACTIONS
8) Introduction
We have prepared various substituted cobaloxime dienes and studied extensively their
reactivities in Diels-Alder reactions.[83, 87, 88] Based on the studies with cobaloxime chemistry, we
conclude that increased exo selectivities were possible with the insertion of the transition
metals in the 2-position of the diene moiety. We have also shown that the main group
substituted dienes, 1,3-butadien-2-yl-trifluoroborates underwent [4+2] cycloadditon reactions
and subsequent cross-coupling reactions under controlled conditions.[89]
Having added advantages such as stability, accessibility, and reactivity in comparison with
other main group metals, we now propose preparation of air-stable, moisture resistant silyl
dienes in order to synthesize 1-aryl-1-cyclohexenes and other cross-coupled cycloadducts. These
dienes can be synthesized efficiently in a few steps from inexpensive, commercially available
starting materials.
We also propose that main group substituted dienes can be transmetalated on to catalytic
quantities of transition metals that will ultimately undergo cycloaddition/cross-coupling
reactions with higher regio and stereoselectivity than cobaloxime dienes. Success of this
reaction relies on the rate of transmetalation, which must be higher than the rate of Diels-Alder
and cross-coupling reactions. This work should help us in developing a one-pot synthesis
methodology where all the reagents were added together (domino) to get the cross-coupled
cycloadduct at the end. Further enhancement of this proposed utility in enantioselective
synthesis is potentially achieved through the use of chiral spectator phospine ligands.
50 Ultimately, this synthetic strategy is expected to lead towards the synthesis of naturally
occurring biologically active compounds such as terpenoids.
9) Literature Review on Synthesis & Cycloaddition Reactions of Silylated
(Conjugated) Dienes:
Over the past three decades, organosilicon chemistry has undergone dramatic change from
the traditional Diels-Alder reactions to the present cross-coupling reactions. During the process,
lots of new silicon-based reagents and reactions have been discovered and made available
commercially[90] due to the versatile properties of the silicon element, for example, polarization
of the silicon-carbon bonds in the sense Siδ+, Cδ- results in ready cleavage by ionic reagents. The
ability to form hypervalent silicon leads to facile nucleophilic attack on silicon and electrophilic
attack on carbon. In general, carbocations β (Si-C-C+) and carbanions α (Si-C-) to silicon are
favoured. The chemistry of allyl, vinyl, and aryl silanes have received considerably more
attention than the conjugated silyl diene chemistry.[91-99] Based on the transition metal
involvement, methods of silyl diene synthesis were divided into two categories.
9.1) Synthesis of silyl dienes & cycloadditions (organic approach)
9.2) Transition-metal mediated silyl diene synthesis & cycloadditions
9.1) Synthesis of silyl dienes & cycloadditions (organic approach):
In this section, approaches toward silyl diene synthesis without using any transition metals
will be discussed.
Synthesis of 1-trimethylsilyl-1,3-butadiene (9.1.3) was first reported by Sadykh-Zade et al[98]
in 1957 by dehydration of 2-hydroxy-1-trimethylsilyl-3-butene (9.1.1) with potassium hydrogen
sulphate (9.1.2). This diene (9.1.3) was characterized as its corresponding cycloadduct (9.1.5)
with maleic anhydride (9.1.4a). This work did not receive much attention until the mid-seventies
51
SiMe3
O
SiMe3
SiMe3 SiMe3
O O+
+ +
+
SiMe3 SiMe3
SiMe3SiMe3 SiMe3
SiMe3
CO2Me
CO2Me
O
O
O
O
MeO2C
CO2Me
MeO2C
CO2Me
O
O
O
O
3.2:1.0 (42%) 1.1:1.0 (77%)
1.2:1.0 (52%)1.0:1.0 (32%)
(48%)
9.1.3
Scheme - 9.1.2: Poor regioselectivity due to electron poor and non-steric silyl group in Diels-Alder reactions
O
O
O
O
O
O
MeO2C CO2Me
O OO
O
when a number of new and practical approaches were made towards the preparation of
these dienes (Scheme-9.1.1).
Fleming[100] studied the reactivities of the 1-trimethylsilylbutadiene (9.1.3) with
unsymmetrical dienophiles and concluded that electronics would dictate the outcome of the
Diels-Alder reaction. As the silyl group was neither electron rich nor bulky to influence the
selectivity, the result was a lack of regio selectivity (ortho favored) and mainly depended on the
EWG of the dienophile (Scheme-9.1.2).
52 The high affinity between silicon and oxygen makes the olefination reactions most
valuable in the formation of carbon-carbon double bonds. Three different approaches have
been reported.[98] First, treating α,β-unsaturated carbonyl compounds having a silyl substituent
(9.1.6) with α-substituted organometallic reagents (9.1.7) followed by dehydration results in the
formation of diene (9.1.8) quantitatively.[100, 101] Using the Grignard reagents instead of
compound (9.1.7) were also known but the yields would be low (Scheme-9.1.3).
In the second approach,[102] 1,1-bis(trimethylsilyl)methyllithium (9.1.9) was used with non-
enolizable α,β-unsaturated carbonyl compounds (9.1.10) to yield the disubstituted conjugated
diene (9.1.11) after workup (Scheme-9.1.4).
The third approach involves reaction between 1,3-bis(trimethylsilyl)propenyllithium (9.1.12)
and carbonyl compounds in the presence of anhydrous magnesium bromide.[103, 104] The
resulting silanols (9.1.13), when treated with acid or silica, afford the 1(E), 3(E)-1-trimethylsilyl
dienes (9.1.14) in moderate yields. Alternatively, the elimination reaction can be carried out
using potassium hydride which yields (1E, 3Z)-1-trimethylsilyldiene (9.1.15) (Scheme-9.1.5).
53
Scheme - 9.1.6: Synthesis of trimethylsilyl dienes by pyrolysis of 3-sulfolenes
9.1.16
9.1.18
9.1.17
9.1.20
9.1.3
SO O
SO O S
O OS
O O
SO O
TMS
TMS
a
b c
TMS TMS
c
TMS
Reaction conditions: (a) i. nBuLi (1.0 eq), -105 °C; ii. TMSCl (0.67 eq).
(b) i. nBuLi (1.0 eq)/NaI (1.0 eq), -105 °C; ii. TMSCl (1.0 eq).
(c) Thermolysis, 240 °C.
TMS TMS
Li 1. MgBr2R
TMS
HO
TMS
KH
H3O +
R TMS
RTMS
Scheme - 9.1.5: Olefination of carbonyl compounds using 1,3-bis(trimethylsilyl)propenyllithium
9.1.129.1.13
9.1.14
9.1.15
2. RCHO
1
2
3
4
1
2
34
Such silylated 1,3-dienes have also been synthesized through the Wittig reaction, and also
from allylsilanes. The electrophiles preferably attack at the γ-position of the lithiated
allylsilyanes.
Chou et al.[105] reported (Scheme-9.1.6) a method to synthesize silyl dienes from pyrolysis of
3-sulfolene precursors such as 9.1.16. Yields of the quenched sulfolene anions (9.1.17, 9.1.18)
were found to be low (25-45%) as the sulfolenes were proven highly sensitive to the reaction
conditions. In order to overcome the volatility problem with the dienes (9.1.3, 9.1.20) at that
temperature, they used the dienophiles to trap the diene and the yields were reported based on
the mass of the cycloadduct. The use of a symmetrical dienophile in this report precluded any
study of regio- and stereochemical preference.
54 Very recently Takenaka et al
[106] reported the synthesis and isolation of the silyldiene
(9.1.20) quantitatively by nucleophilic addition of the Grignard reagent (9.1.21) generated insitu
from chloroprene (9.1.22) and magnesium metal (9.1.23) to trimethylsilylchloride, 9.1.24
(Scheme-9.1.7).
Mg
ClMg
Scheme - 9.1.7: Synthesis of 2-trimethylsilyl-1,3-butadiene using Grignard addition reaction
9.1.23
9.1.21
aMg
Reaction conditions: (a) i. dibromoethane in THF, r.t; ii. ZnCl2 in THF, ∆, 15 min
(b) i. chloroprene (9.1.22) and dibromoethane in THF, dropwise with gentle ∆; ii. ∆ for 45 min
(c) i. TMSCl (9.1.24) in THF, r.t; ii. canula transfer of 9.1.21 at r.t; iii. ∆ for 3h; iv. work-up
9.1.20
TMS
b c∗
9.2) Transition-metal mediated silyl diene synthetis & cycloadditions:
The silyl diene synthetic methodologies involving the use of transition metals are reported
under this category.
In 1978, Batt and Ganem[107] reported a method to make the 2-triethylsilyl-1,3-butadiene
(9.2.2) by catalytic hydrosilylation of 1,4-dichloro-2-butyne (9.2.1) with triethylsilane (9.2.3)
using chloroplatinate, H2PtCl6 (9.2.4) followed by reduction with zinc dust. When subjected to
Diels-Alder reaction conditions, this diene did not result in any better selectivity than the
terminal substituted silyl diene (Scheme-9.2.1).
55
Br
BrSiMe3
Ph
Scheme - 9.2.2: Synthesis of trimethylsilyl diene from 2-bromoallylbromide in presence of nickel catalyst
9.2.59.2.6
Reaction conditions: (a). Benzylmagnesium bromide, NiCl2(dppp)
(b). (E)-2-Trimethylsilyl vinylmagnesium bromide (9.2.7)
a b
1-Silyl-substituted diene (9.2.6) can be synthesized from 2-bromoallyl bromides
(9.2.5) by treating with 2-trimethylsilyl vinyl magnesium bromide (9.2.7) in the presence of a
catalytic amount of NiCl2·(dppp) (Scheme-9.2.2).[108]
Suzuki et al. reported the synthesis of (E)-olefins (9.2.10) by a stepwise cross-coupling
reaction using organozinc chloride (9.2.8), (E)-(2-bromoethenyl)dibromoborane (9.2.9), and
palladium catalyst (Scheme-9.2.3).[109]
Trost and Mignani[110] reported (Table-9.2.1, Scheme-9.2.4) the attempted generation of 2-
(trimethylsilyl)buta-1,3-diene (9.1.20) by palladium catalyzed elimination of 3-acetoxy-2-
(trimethylsilyl)-1-butadiene (9.2.11) led instead to the formation of an octatriene compound
through the dimerization of the desired diene. This observation suggests that the desired diene
is produced but its conversion to dimer is rapid. Having that evidence, they trapped the diene as
soon as it was formed with excess dienophile by using a tandem elimination-cycloaddition
56 reaction. As the silicon substituent is not a strong directing group both regio isomers were
formed with slight preference of the para isomer (1.2-2.5 : 1).
Nickel-catalyzed olefination of allylic and benzylic dithioacetals have been shown to be useful
in the preparation of silylstyrenes and silylbutadienes.[111] These reactions are considered to
involve the formal substitution of a carbon-sulfur bond by the Grignard addition, followed by
the oxidative addition of Ni(0) to displace the other carbon-sulfur bond and β-hydride
elimination produced the (E)-vinylsilanes exclusively (Scheme-9.2.5).
Synthesis of allylic acetate (9.2.11):
Plausible reaction mechanism
9.2.11 (88-95%)
TMS
Br
TMS
Li
TMS TMS
R
OH
R
OAc
RCH2CHO AcCl
DMAP
54-56%
R = H, MeTMS
Pd
LnOAc
EWGpath - A
TMS
PdEWG
Ln
AcOH
Diels-Alder
TMS
EWG
TMS
EWG
PdOAc
Ln
TMS
EWG
PdLn
path - B
ring closure &reductive elimination
Pd insertion
β-hydride elimination andπ-allyl complex generation
Scheme - 9.2.4: Tandem Pd-catalyzed elimination and cyclization reactions of allylic acetates (9.35)
Entry Dienophile Reaction Yield Ratio
time (h) (adducts) (7:8)
1. methyl acrylate 10 68 64:36
2. ethyl acrylate 10 70 67:33
3. nbutyl acrylate 8 69 53:47
4. acrylonitrile 12 88 59:41
5. acrylamide 12 50 56:44
6. methyl vinyl ketone 5 72 66:34
7. ethyl vinyl ketone 5 68 71:29
8. dimethyl maleate 12 62 ---
9. dimethyl fumerate 12 50 ---
Table - 9.2.1
nBuLi
57
Scheme - 9.2.5: Synthesis of silylstyrenes and silylbutadienes from dithioacetals using nickel catalyst
S
SAr
R
Ar
R'R
R'CH2MgX
NiCl2(PPh3)2
Dithioacetal Grignard reagent Product
MeMgI
Me3SiCH2MgCl
Me3SiCH2MgCl
MeMgI (or)
Me3SiCH2MgCl
MeMgI (or)
Me3SiCH2MgClSS
TMS
TMS
SS
TMS TMS
TMS
s
s
TMS
TMS
SSO
TMS
O
SS
TMS
TMS
Ph
Dithioacetal Grignard reagent Product
1,2-Dialkylidenecycloalkanes are known as important building blocks in the synthesis of
polycyclic molecules.[112] This class of compounds can be made by the cyclization of 1,n-diynes
using either titanium or zirconium metals quantitatively or palladium, nickel and chromium
complexes catalytically. Also they can be prepared from 1,4-elimination reactions of the
allylsilane precursors. All of these reactions will give the (E)- or (E,E)-diene moieties. Whereas
using the hydrosilylation of 1,7-diynes (9.2.12) with nickel (0) catalysts led to the formation of
(Z)-exocyclic silyl dienes (9.2.13a-e) which are synthetically equivalent to the exocyclic
dienol.[112] Transformation of silicon-carbon into carbon-carbon bonds by using cross-coupling
reactions does not alter the (Z)-configuration. The reaction involves first the coordination of
Ni(0) to the alkyne and oxidative addition (step-1), followed by carbometalation (step-2), ring
closure (step-3), and reductive elimination (step-4) as shown below (Scheme-9.2.6).
58
Scheme - 9.2.6: Synthesis of (Z)-exocyclic silyl dienes by Ni(0) catalyzed hydrosilylation of 1,7-diynes
9.2.119.2.12a-e
H
R
H SiX3+
H
SiX3
H
R
9.2.12a. SiX3 = Si(OEt)3 70%
9.2.12b. = SiMe(OEt)2 68%
9.2.12c. = SiMe2(O-iPr) 67%
9.2.12d. = SiMeEt2 55%
9.2.12e. = SiMe2(NEt)2 52%
(Z:E = 94:6)
Ni(0)
H
R
NiSiX3
H
R
Ni H
H
SiX3
H
SiX3
Ni
R
H
1
23
4
Synthesis of 2-aryl-3-trimethylsilyl-1,3-butadienes (9.2.15) was reported recently using a
Ni(0) catalyst. In this protocol, low valent Ni(COD)2 was used to do the sequential
carbometallation of the aryl halide to the propargyl derivative of the silyl compound followed by
cross-coupling reaction with bis(iodozinc)methane (9.2.13). The resulting allylzinc derivative
(9.2.14) was transformed to the arylsilylbutadienes (9.40) in excellent yield (Scheme-9.2.7).[113]
59
Murphy et al.[114] have used a different approach in making alkyl / aryl silyl butadienes
(9.2.18a-h). The Pt (0) catalyst was used in hydrosilylation of 2-propynyl alcohols (9.2.16a-e)
which produced the silylated allylic alcohols (9.2.17a-i) in moderate yields. These alcohols are
readily converted into the aryl / alkyl silylbutadienes by using simple dehydration (9.2.18a-f, h)
or a Wittig reaction (9.2.18g, h). The same protocol was further expanded to make the tethered
dienes (9.2.19), which could undergo the type-1 intramolecular Diels-Alder (Type-1 IMDA)
reactions to give the cycloadducts (9.2.20) (Scheme-9.2.8).
60
Br Si
Si
OH
Si Si
H
PhPh
PhPh
Ph
Phd e f g
Ph Ph
H
Scheme - 9.2.8: Synthesis of silyl dienes and Type-1 IMDA reactions of tethered silyl dienes
OH
R1
R2
SiR32R4
R1 OHR2
SiR32R4
R2
SiR32R4
R2
a
b
c
Z
OH
Ph3Si OH
Me
Me
Ph3Si
OH
Ph3Si
a+
b
c
9.2.18g
9.2.16a-d 9.2.17a-f
9.2.19
9.2.18a-f
9.2.18h
9.2.17g
9.2.17h
9.2.16e
9.2.18i 9.2.20
Reaction conditions: a). HSiR32R4, [Pt]0; b). , H+ / -H2O; c). R1 = H; i). PCC ii). ZCHPPh3; Z = H, R, Ar, CN, COR, CO2R
Reaction conditions: d). Mg-Et2O then ClHSiPh2; e). 9.2.16a, catalyst 7, THF, , 3 h; f). , toluene, CSA (10% w/w), 2 h;
g). xylene, 180-200 °C, 40 h
9.2.16a: R1, 2 = Me 9.2.17a: R1, 2 = Me, R3, 4 = Ph 9.2.18a: R2 = Me, R3, 4 = Ph
9.2.16b: R1 = Me, R2 = Ph 9.2.17b: R1 = Me, R2 - 4 = Ph 9.2.18b: R2 - 4 = Ph
9.2.16c: R1 = Me, R2 = H 9.2.17c: R1 = Me, R2 = H, R3, 4 = Ph 9.2.18c: R2 = H, R3, 4 = Ph
9.2.16d: R1 = Me, R2 = Et 9.2.17d: R1 = Me, R2 = Et, R3, 4 = Ph 9.2.18d: R2 = Et, R3, 4 = Ph
9.2.17e: R1 - 3 = Me, R4 = Ph 9.2.18e: R2, 3 = Me, R4 = Ph
9.2.17f: R1, 2 = Me, R3, 4 = Et 9.2.18f: R2 = Me, R3, 4 = Et
Si
O
Si
Pt PtBu3
catalyst 7
OS
O
OOH
Camphorsulphonic acid
(CSA)
Type-2 IMDA reactions were reported by Shea and co-workers[115] to make the bicyclo[5.3.1]
ring systems, which are crucial for the total synthesis of Plocamium marine natural products.
Deprotonation of the alcohol (9.2.21) with Grignard reagent was followed by reacting with Mg
to get the Normant-Grignard reagent (9.2.22), which was then cross-coupled to chloroprene via
Hosomi’s protocol using nickel catalyst. The silyl diene formed was tethered with an acid
chloride in-situ. The trienyl silane (9.2.23) formed underwent an IMDA reaction to give the
bridge head allylsilane compound (9.2.24) with high stereoselectivity during which two
quaternary carbon centers were formed (Scheme-9.2.9).
61
In 2004, Clark and Woerpel reported the reaction of a silacyclopropene (9.2.25a)[116] with a
protected enynol (9.2.26a) to produce a siloxacyclopentene containing a silicon substituent at
the terminal position of a 1,3 diene moiety (9.2.27a, 9.2.27b) as non-separable regioisomers in
moderate yields.[117] These dienes were reacted with N-phenylmaleimide (9.1.4b) in a Diels-
Alder reaction to yield the cycloadducts. Even though the exo-selective Diels-Alder reaction was
not expected to give high facial selectivity with the chiral oxasilacyclopentene 9.2.28b, 4:1
diasteroselectivity was reported (Scheme-9.2.10).
Also in 2004 Lee and co-workers reported the synthesis of a number of siloxacycles that are
part of a 1,3-diene unit via a condensation/metathesis strategy using alkenyl alcohols and
TIPSO
SiO
TIPSO
R2
R1tBu
tBu
PhN
OSiO
O
OTIPS
R2
R1
tButBu
9.2.26a
9.2.27a: R1 = R2 = Et (54%, 98:2)
9.2.27b: R1 = Ph; R2 = Me (58%, 89:11)
9.2.28a: R1 = R2 = Et (76%, 99:1 dr)
9.2.28b: R1 = Ph; R2 = Me (69%, 4:1 dr)
Reaction conditions: a) i. Ag3PO4 (10 mol%), 1; ii. CuI, Et2CO (or) PhCOMe; b) 9.1.4b, 130 °C, 6-9 d
Si(tBu)2a b
silacyclopropene(9.2.25a)
Scheme - 9.2.10: Synthesis of oxasilacyclopentene and its cycloaddition reaction with 9.1.4b
Scheme - 9.2.9: Type-2 IMDA reactions of tethered silyl dienes
Si
Cl
Cl
SiOH
Cl
SiOMgBr
MgCl
Cl
O R3
R2
R1
Si
O
O R1
R3
R2
R1
R2
R3
OOSi
9.2.21 9.2.22 9.2.23 9.2.24
Reaction conditions: a) i. KOAc; ii. MeOH, H+; iii. tBuOCl, PPh3
b) i. MeMgBr; ii. Mg
c) i. NiCl2(dppp), chloroprene; ii.
d) ∆, 200 °C, toluene
a b c d
62 alkynyl silanes.[118] No Diels-Alder or cross coupling reactions of these substrates were
reported (Scheme-9.2.11).
10) Literature review on cross-coupling reactions:
Transition metal catalyzed cross-coupling reactions have become the most important
synthetic tool in acheiving the stereoselective synthesis of carbon-carbon double bonds. The
well established Stille-Migita-Kosugi coupling reactions of organostannanes and the Suzuki-
Miyaura coupling of organoboron compounds are the two reactions regarded as the most
effective among this class of reactions. Their wide application and extraordinary synthetic usage
have provided the stimulus to develop newer and more effective methods (Scheme-10.1).
Organosilanes were originally thought to be unreactive towards cross-coupling reactions. The
small difference in the electronegativity between silicon and carbon resulted in a weak
nucleophilic reagent for cross-coupling reactions. The early work of Hiyama[119-121] demonstrated
that in the presence of a nucleophilic promoter such as fluoride, a hypervalent pentacoordinate
Scheme - 9.2.11: Synthesis of siloxacycles, 9.2.29
OH
nSi
R
Ph
H
PhO
Si
PhPh
R
n
OSi
R
Ph Ph
n(a)
[RuCl2(p-cym)2]
(b)
Grubbs catalyst (2nd gen.)
+a b
63 “ate” complex was postulated to undergo a facile coupling reaction due to the increased
polarization at the carbon-silicon bond. The silicon compounds were known for non-toxicity,
have low molecular weight and their incorporation into the organic molecules by various
methods makes these reactions superior to the methods previously employed.
Kumada reactions,[111-113] Stille reactions,[122] and Hiyama reactions[121] are typical examples
for transmetallion of silicon compounds with palladium and nickel complexes. Several other
reactions were also reported using rhodium[123] and platinum[124] catalysts.
For the sake of convenience, we have organized the silyl cross-coupling reactions under two
categories based on the silyl activator viz. fluoride-assisted and non-fluoride assisted cross-
coupling reactions of silanes.
10.1) Fluoride-assisted cross-coupling reactions of silanes: There are several reports
available on the cross-coupling reactions of the various silyl compounds with a large pool of
coupling partners and reaction conditions. We will try to explain a few examples, which have
some relevance to the present study i.e. vinyl and aryl silyl compounds.
10.1.1) Cross-coupling reactions of vinyl silanes: Prior to 1988, only a few examples of neutral
alkenylsilanes undergoing desilylative coupling reactions in the presence of Pd catalyst with aryl
halides were known. They became less attractive as these reactions lead to the formation of
regioisomers and substrates were limited to alkenylsilanes (Scheme-10.1.1).
64
In 1988, Hiyama & Takanaka[125] showed a solution for this problem by using a nucleophilic
promoter – fluoride source, which transformed the silicon compounds to pentacoordinate “ate”
complexes which become nucleophilic enough to react with Pd complexes chemoselectively
(Scheme-10.1.2).
Scheme - 10.1.1: Non-activated desilylative cross-coupling reactions leading to regioisomers
TMS
R
TMS
R
+ +
51-60% 5-25%
Reagents and conditions: a). Pd(OAc)2 (2.0 mol%), PPh3(4.0 mol%), Et3N (1.4 eq), DMF, 70-125 °C
b). Pd(dba)2 (5.0 mol%), MeCN, 25 °C
c). Pd(dba)2 (10.0 mol%), MeCN, 25 °C
R = H, OMe, NO2, Me
Ph
TMS
Ar
Ph Ph
Ar
ArPh
+ +
Ar = Ph, 4-Me-C6H4, 4-Br-C6H4, 4-NO2-C6H4
+ 58 - 86% 14 - 42% : 0%
TMSPh
TMS
Ph
+
+
(Yield = 97-100%)
70 - 80% 20 - 30% : 0% (Yield = 66-100%)
96 - 99% 0% : <1 - 4% (Yield = 96-100%)
a
b
c
c
R
I
ArN2+BF4
-
ArN2+BF4
-
ArN2+BF4
-
65
Scheme - 10.1.3: Cross-coupling reactions of alkenylfluorosilanes
n-Hex
SiMe3-nFn
I
+
n-Hex
2.5 mol% of PdCl( 3-C3H5)]2
TASF(1.0 eq)
THF, 50 °C
n time (h) % yield0 24 01 10 812 48 743 24 0
Having an aliphatic substitutent on the vinylsilanes failed to couple with aryl halides under
the conditions mentioned above. When the methylene groups (one or two) were replaced with
fluorine, the alkenylfluorosilanes coupled with aryl halides in good yields. The success of the
reaction was attributed to the electron donating nature of the aliphatic substitutent which
prevents the formation of pentacoordinate silicates (Scheme-10.1.3).[126]
The groups attached to the aryl halide influenced the formation of cine-coupled products
along with the required ipso-coupled products which is a common problem in Stille coupling
reactions (Scheme-10.1.4).[127]
Scheme - 10.1.4: "Cine product" formation and group effect in Hiyama coupling reactions
ipso product cine product
FMe2Si
Ph
I Ar+Ar
Ph Ph
Ar
2.5 mol% of PdCl(η3-C3H5)]2
TASF(1.1 eq)
THF, 60 °C
+
Time % Yield Ratio
Ar = 4-CF3-C6H4 24h 72 93 : 7
4-MeCO-C6H4 20h 73 88 : 12
4-F-C6H4 4h 80 79 : 21
Ph 4h 69 75 : 25
4-Me-C6H4 14h 84 59 : 41
4-EtO-C6H4 20h 63 60 : 40
66
Scheme - 10.1.5: Cross-coupling reactions of dichloroalkylvinylsilanes using -OH as activator
R1
SiMeCl2
n-Hex SiEtCl2
R1 = nBu, Me3Si +
R5X
R2
R3
R4
i. X = Br, R2, R3 = F, R5 = CH
ii. Br/Cl, R2, R4 = H, R5 = CH, R3 = COMe
iii. Br/Cl, R2-4 = H, R5 = N
iv. Br, R2,4 = CF3, R3 = H, R5 = CH
i-viii
coupling products
55-95%
Reaction conditions: a) 2.5 mol% Pd(OAc)2, NaOH (6.0 eq), THF, 60 °C, 5-36h (for aryl bromides)
b) 2.5 mol% Pd(iPr3P)2, NaOH (6.0 eq), THF, 80 °C, 12h (for aryl chlorides)
reaction
conditions
v. X = Br/Cl, R3,4 = H, R5 = CH
vi. Br, R4 = CN, R2,3 = H, R5 = CH
vii. Cl, R2 = Me, R3,4 = H, R5 = CH
viii. Cl, R4 = CF3, R2,4 = H, R5 = CH
Aryl chlorides and aryl/alkenyl triflates can be made good coupling partners with the
organosilicon compounds by replacing the fluoride activator with a hydroxide ion and the
fluoride ligand on silicon with chlorine (Scheme-10.1.5).[128]
The reactivities of alkenyl halides are comparable with aryl halides in cross-coupling
reactions, 1,3-dienes can be synthesized by using alkenyl halides in place of aryl halides
(Scheme-10.1.6).[125]
The Denmark group[129] has developed a new class of organosilanes called siletanes[130] which
underwent cross-coupling reactions readily. The siletanes can be prepared as shown below
(Scheme- 10.1.7).
67
Scheme - 10.1.7: Synthesis of siletanes
H
n-C5H11
Si
n-C5H11
Sin-C5H11
Si
n-C5H11
(E)-1 (E/Z >99/1)
(Z)-1 (E/Z <2/98)
Reaction conditions: a) i. DIBAL-H, hexane, 50 °C; ii. 10.1.1, 50 °C, 2days; 81%
b) i. MeLi/Et2O, -78 °C; ii. 1; 92%
c) i. DIBAL-H, hexane-Et2O; ii. NaF (aq); 82%
10.1.1 = Si
Cl
a (i)
b
c
a (ii)
The added advantage of this class of compound was thought initially to be the increased
nucleophilicity due to the silacyclobutane ring. Upon activation with the nucleophile, the angle
strain in the silacyclobutane was relieved by the transformation from tetrahedral (79º vs. 109º)
to trigonal bipyramid (79° vs. 90°).[131] Alkenylsiletanes (E)- and (Z)- were coupled with aryl
iodides in 10 min. at room temperature under mild conditions. High regiospecificity with respect
to alkene geometry was observed. Whereas the arylsiletanes require higher temperature and
heteroatom substitution at silicon (Scheme-10.1.8).[130]
68 Later, it was found that silacyclobutanes were first converted to alkenyl(propyl)silanols by
hydrolysis under the reaction conditions[132] and these were shown to be highly reactive. The
reactivity of silanol compounds in coupling reactions can be enhanced by using silanol cross-
coupling systems developed by Denmark et al. for which they have chosen Pd(dba)2 as the
catalyst and TBAF as the effective promoter. By having these advantages they reported the
cross-coupling reactions of highly substituted alkenylsilanols with aryl iodides (Scheme-
10.1.9).[133]
(α-Alkoxyalkenyl)silanols (10.1.3) can be synthesized (Scheme-10.1.10) by treating the
dihydropyran (10.1.2a) with tBuLi and subsequent quenching with hexamethylcyclosiloxane
(trimer) (10.1.4) resulted in the formation of silanol (10.1.3a) in moderate yields. Attempts
made to synthesize the other α-alkoxydimethylsilanols in the same process mentioned above
resulted in impure, non-separable mixtures. The other attempted process involves the
generation of silyl hydrides (10.1.3b-d) as an intermediate. To their surprise,[132] these silyl
hydrides (10.1.3b-d) themselves couple readily without the need of silanols. In all of these
reactions, in place of Pd(dba)2 they used [(allyl)PdCl]2 as the catalyst to avoid contamination
during the purification of cross-coupled products (Scheme-10.1.11).
69
10.1.3a10.1.2a
10.1.4
O
O
O
O O
OBu
OBu
Reaction conditions: a) i. tBuLi, THF, -78 °C 0 °C; ii. (Me2SiO)3 (10.1.4), -78 °C 0 °C
b) i. tBuLi, THF, -78 °C 0 °C; ii. i-Pr2Si(H)Cl, -78 °C 0 °C
c) i. nBu4N+F- or nBu4N+OH-; ii. 2.5 mol% [allylPdCl]2, THF, r.t
SiOH
O
SiH
i-Pri-Pr
Si
H
i-Pr
i-Pr
SiH
i-Pri-Pr
a
b
b
b
---
75%
71%
72%
YieldSi
OSi
O
SiO
Scheme - 10.1.10: Synthesis of ( -alkoxyalkenyl)silanols
10.1.3b
10.1.3c
10.1.3d
10.1.3a
I
R2 +
c
c
c
O
O
OBu
R1
R1
R2
R2
R2
Scheme - 10.1.11: Cross-coupling reactions of( -alkoxyalkenyl)silanols
Yield: 71-94%
10.1.2a
10.1.2b
10.1.2c
10.1.3b
10.1.3c
10.1.3d
Scheme - 10.1.12: Synthesis of silylethers by hydrosilylation and its cross-coupling reactions
OH
O
OH
SiHSi Oa b c
X
R R
+
Reaction conditions: a) i.i-Pr2Si(H)Cl, Et3N, DMAP, Pentane, 80%
b) i. H2PtCl6 6H2O, CH2Cl2, 83%
c) i. nBu4N+F- (TBAF); ii. 5.0 mol% Pd(0), THF, r.t-45 °C, 45%-88%
Alkylidenesilacyclopentenes can be generated by intramolecular hydrosilylation of
homopropargylic alcohols using a Pt(0) catalyst. These compounds undergo facile coupling
reactions with alkenyl and aryl halides in the presence of Pd(0) and TBAF (Scheme-10.1.12).[134]
10.1.2) Cross-coupling reactions of arylsilanes: Deshong et al.[135] reported the cross-coupling
reactions between organo trialkoxysilanes and aryl halides. This study showed a wide array of
alkoxysilyl compounds having aryl, vinyl, and allyl groups and their cross-coupling reactions with
aryl iodides, electron-deficient aryl bromides, and allylic benzoates. The electronic nature of the
groups does not show any effect in the cross-coupling reaction. However, these alkoxysilanes do
not show any reactivity towards the aryl triflates. Cross-coupling of arylsilyl ethers with aryl
70 chlorides has also been possible by using the phosphine ligand, 2-
(dicyclohexylphosphino)biphenyl, which is known to activate aryl chlorides in Pd-catalyzed
coupling reactions (Scheme-10.1.13).
The siloxanes can be prepared by either metalation (Li/Mg) from the corresponding aryl
halide followed by the nucleophilic addition to tetraalkyl orthosilicates (Scheme-10.1.14)[136] or
by Pd(0)[137]- or Rh(I)[123]-catalyzed silylation of aryl halides with trialkoxysilanes (Scheme-
10.1.15).
In 2003, Deshong et al.[138] developed a protocol to promote cross-coupling reactions of aryl
triflates by using silatranes (Figure-10.1.1). The aryl silatranes can be synthesized by alcoholysis
of the aryl siloxane using triethanolamine in refluxing toluene. The alcohol was removed as soon
as it was formed during the reaction by using the Dean-Stark apparatus.
71
Si
N
O
O
O Si
N
O
O
O
••
Figure - 10.1.1: Resonance structures of arylsilatrane
The characteristic features of these compounds are:
i) Stable under standard hydrolysis and alcoholysis conditions.
ii) Crystalline solids, monomeric, stable, excellent yields, and do not polymerize.
iii) Easy to prepare from its siloxane precursors.
From their initial studies it was revealed that the dative bond in the pentacoordinate
silatrane was not sufficient to promote the phenyl transfer. However, using TBAF with 10-20
equivalents of H2O, the silatrane was found to couple with aryl triflates. The optimum conditions
for this reaction were H2O / TBAF (20: 1) and use of the Buchwald ligand. It is noteworthy to
mention that silatranes would undergo the coupling reactions with aryl iodides and bromides
but the yields were low compared to its counterpart trialkoxyarylsilanes.
To overcome the problems in the silatrane reactions (like the requirement of water that
causes the competing hydrolysis of the triflates) they[139] have shown the preparation and cross-
coupling reactions of pentavalent aryl and heteroaryl bis(catechol)silicates with aryl triflates in
the presence of TBAF, Buchwald ligand and catalytic amount of Pd(dba)2. These compounds
were also shown to couple with electron rich aryl iodides (Scheme-10.1.16).
72
10.2) Non-fluoride mediated cross-coupling reactions of silanes:
With very few exceptions, all of the cross-coupling reactions involving silicon compounds
require the fluoride source as an activator. Fluorides are incompatible with several functional
groups like common silyl protectors, and labile silicon reagents with oxygen or halogen on
silicon and this undermines the application of this protocol.
In order to overcome the problems associated with fluoride activators, Mori et a.[140]
discovered that silver (I) oxide can also be used as an effective activator for Pd catalyzed
coupling of alkenylsilanols with aryl iodides. Preference for iodide was noted in the presence of
bromide and triflate (Scheme-10.2.1).
As the silanol having one hydroxyl group required longer reaction times and elevated
temperatures, Denmark’s group[129] reported the synthesis of silanediol and silanetriol from the
corresponding chlorides, which showed enhanced reactivity and yields compared to the silanol
reactions reported by Mori et al (Scheme-10.2.2).
The two notable properties of the Ag2O in promoting the coupling reactions are: i) The
oxygen atom of the Ag2O acts as a nucleophile to activate the silicon and generates the
73 hypervalent silicon intermediate. ii) Silver atom promotes the halide extraction from the
arylpalladium species. Likely this would generate a more reactive cationic palladium species.
Hiyama et al[141] recently reported the synthesis of alkenyl- and aryl[2-
(hydroxymethy)phenyl]dimethylsilanes and their cross coupling reactions with organic iodides
under mild reaction conditions (Scheme-10.2.3).
These are the first reported reactions on the recovery of the silicon after the cross-coupling
reactions (Scheme-10.2.4).
Perfluoroalkyl or perfluoroaryl compounds with amines in the α-position have gotten
considerable attention as they serve as potential pharmaceutical and agrochemical agents.
Three component one pot silicon Mannich reactions were proposed to synthesize the
pentafluorophenylmethylamines using aldehydes, secondary amines, and alkoxytris-
(pentafluorophenyl)silanes (Scheme-10.2.5).[142]
74
11.1) A brief outlook on tandem reactions: The tandem reaction can be defined as “the
combination of two or more reactions which occurs in a specific order, and if they need any
sequential reagent addition the secondary reagents must be incorporated into the
products”.[143] These reactions were considered eco-friendly due to minimal use of the solvents
as the reactions are carried out without the isolation of the intermediates and help in attaining
the large degree of complexity. These reactions are also important in industrial applications as
they minimize the required reagents, work force and time (Scheme-11.1.1).[144]
In general, tandem Diels-Alder reactions involve the generation of dienes or dienophiles in-
situ and trapped by the reaction partner which is already present.[98, 105, 110] Usually this kind of
transformation is common in intramolecular Diels-Alder reactions. If the reacting partners are
highly reactive then intermolecular Diels-Alder reactions also happen and the reacting partners
were added prior to the reactions as trapping agents.[105]
Scheme - 10.2.5: Silicon-Mannich reactions for syntheis of pentafluorophenylmethylamines
O
R1
NR2
R OH
N
R1 Si
HO OMe
C6F5C6F5
C6F5
NR2
R1 C6F5
R RR2NH MeOSi(C6F5)3
75
11.2) A brief outlook on domino reactions: According to Tietze,[145] “A domino reaction is
a process involving two or more bond-forming transformations (usually C-C bonds), which takes
place under the same reaction conditions without adding any additional reagents and catalysts,
and in which the subsequent reactions result as a consequence of the functionality formed in
the previous step”. According to the mechanism of the first step, these reactions were classified
into cationic, anionic, radical, pericyclic, and transition-metal induced transformations.
Combinations of the same type of reactions are called homo-domino reactions and that of
different types in sequence are called hetero-domino reactions. Homo-domino reactions are
more common in the literature. The following scheme-11.2.1 shows the generalized transition-
metal, Pd(0) catalyzed domino reactions.[146]
11.3) Alkoxy silyl conjugated dienes – literature precedence: Silicon compounds have
been utilized in cross-coupling reactions since the invention of silicon activation in presence of
fluoride reported by Hiyama et al. in 1988.[125] There are several reports in the literature
showing the versatility and ubiquity of the silyl compounds in cross-coupling reactions. Silicon
has the ability to transfer various groups like vinyl, aryl, alkyl, alkenyl, pyridinyl, and other
organo groups in cross-coupling reactions with catalytic quantities of transition metal. However,
Scheme - 11.2.1: Schematic representaion of domino reactions
BrPd(0)
A
B C∆
Br +
RPd(0)
R
∆
R
X
Y
Pd(0)∆ R
R
R
RR
76 not many reports were known about the synthesis of alkoxysilyl conjugated dienes and their
reactions. Atsuhiro et al reported and received a patent for the synthesis of the trialkoxysilyl-
1,3-butadiene using Batt and Ganem’s[107] method (Scheme -11.3.1)
The cycloadduct resulting from the reaction with maleic anhydride (9.1.4a) was reported to
be useful as the starting material for silicon containing polyester and polyamide resins, silane
coupling agents, plasticizers for vinyl chloride resins and as curing agents for epoxy resins[147] (US
Patent 4837339).
77
12) Aim and Scope of the Present Study: Our goal in this research study is to
develop a methodology for a one-pot three component catalytic system to enable the
stereoselective syntheses of substitututed arylcyclohexenyl systems. These compounds are key
components of naturally occurring biologically active natural products such as terpenoids. From
a pharmaceutical and agricultural point of view, these terpenoid compounds have vast utility
and their ever challenging stereo complexity lures organic chemists to come up with better
selective synthetic methodologies. From our earlier experience with cobaloxime diene
chemistry, we inferred that enhanced stereoselectivity (exo) was possible with low-valent
transition metals substituted on the 2- position of the diene moiety. It is evident from
contemporary studies that silicon compounds will transmetalate easily on to catalytic transition
metals during the cross-coupling reactions. The reaction mechanism for the Hiyama cross-
coupling reaction is outlined below (Scheme-12.1).
Scheme - 12.1: Schematic representation of the Hiyama coupling reaction
L2Pd X R
F3Si R'F
Si R'
F
F
FTBAF
R
PdL X
L
L
PdL R'
R
R
PdL R'
L
R' R
FSi X
F
F
FNBu4
oxidativeaddition
transmetalation
trans-cis
isomerization
reductiveelimination
+
NBu4
78 In the usual Hiyama cross-coupling reaction, the first step is oxidative-addition of Ar−X
followed by the transmetalation and reductive elimination. In order to attain our goal, we
have to develop a system where the transmetalation happens first followed by Diels-Alder
reaction and then cross-coupling (Scheme-12.2).
79
BF3K
RhLn2
Transmetalation
Ln2Rh
MeO2C
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
[Rh(acac)(C2H4)2] + Ln
[Rh(acac)Ln2]
H2O
acac
H2O
Ln = S-BINAP
Ln2Rh OH
Diels-Alder
Demetalationcatalyst
regeneration
Scheme - 12.3: Proposed reaction mechanism for catalytic exo &enantio selective Diels-Alder reactions
Hopefully, this can be achieved by choosing a transition metal (M) with an oxidation state
of M(I) or M(II), probably our first choice would be M(II).[148-153] The success of the catalytic cycles
involving M(II) catalysts mentioned in Scheme-12.2 depends on the following factors: 1)
Transmetalation and cycloaddition reaction must be faster than the oxidative addition of Ar−X
(PATH - A); or 2) Reductive elimination should be slower than all the other reactions (PATH - B);
or 3) The cycloaddition reaction of the transition-metal dienyl complex should take place faster
than 1,4-addition with the dienophiles (PATH - A & B). Overall, oxidative addition should be
slower than the transmetalation & the cycloaddition reaction should be faster than 1,4-addition
with dienophiles. At this stage, we cannot rule out the possibility of a catalytic pathway involving
M(0) initiator which starts with oxidative addition followed by transmetalation and Diels-Alder
reaction when the reductive elimination is the rate determining step (PATH - C).
From unpublished results,[154] we know that it is possible to get the transmetalation before
the cycloaddition reaction of the main group diene, dienyl borate under the controlled
conditions (Scheme-12.3).
80 We are envisioning that this kind of reaction will work with the silyl compounds also
because of the similarity in their electronic nature and reactivity. Upon developing the reaction
conditions for the catalytic cycle, we will carry out the asymmetric version by employing
commercially available chiral phosphine ligands.
The silyl group in silyl diene is neither electron rich nor a strong directing group – and will
likely give poor selectivity in cycloaddition reactions both regio- and stereospecifically. Hence we
won’t pay much attention towards achieving higher stereoselectivity with silyl dienes. In order
to prove the principle with the novel silyl dienes synthesized in our lab, we propose to carry out
a few representative examples of Diels-Alder reactions with various substituted dienophiles. For
the purpose of the cross-coupling reactions of the same, we will use the cycloadducts derived
from the cycloaddition of the symmetrical dienophiles.
81
13) Results and Discussion: As a first step, to execute the proposed project, we have
chosen to prepare 2-trialkoxysilyl-1,3-butadiene (11.3.2b). The reasons for selecting the
compound 11.3.2b as the primary choice are as follows:
1) Trialkoxysilyl groups are known to form pentacoordinate “ate” complexes readily during the
cross-coupling reactions (compared with trialkylsilanes).[129]
2) These compounds are also known for their ligand exchange reactions to make the stable
silyl dienes (13.1.2a, 13.1.2c) in the solid form (no polymerization).
3) Building the steric bulk around the silicon will enhance the regio selectivity.
4) Having the anionic silyl group like compound 13.1.2c may result in higher reactivity.
5) 2-Substituted dienes are proven for higher selectivities in Diels-Alder reactions compared to
terminal substituted dienes.[155]
13.1). Synthesis of air-stable, moisture resistant monomeric 2-silyl-1,3-butadienes and their
reactions. 2-Triethoxysilyl-1,3-butadiene (11.3.2b)[156, 157] can be prepared quantitatively in multi
gram scale from commercially available starting materials. The compound 11.3.2b in xylenes
was prepared by the nucleophilic addition of 1,3-butadienyl-2-magnesium chloride (generated
in-situ from chloroprene, and Mg metal) to the triethoxysilylchloride as shown below (scheme-
13.1.1).[106, 158] The title compound was isolated as a light yellow-brown liquid after distillation
under reduced pressure. This compound slowly polymerizes on standing at room temperature
over a period of time (stable at low temperature, -20 °C).
82
2-Triethoxysilyl-1,3-butadiene can be used in the subsequent cycloaddition reactions or in
the ligand exchange reactions to make the dienes (13.1.2a, c) in solid forms. Alcoholysis of
compound 11.3.2b with triethanolamine in the presence of catalytic amount of KOH results in
the formation [buta-1,3-dien-2-yl]silatrane (13.1.2a)[156, 157] as a light yellow solid (Scheme-
13.1.1).
Reacting compound 11.3.2b with catechol in the presence of KOH yields potassium [bis(1,2-
benzenediolato)-1,3-butadien-2-yl-]silicate (13.1.2c)[156] as a white amorphous powder (Scheme-
13.1.1).
Buta-1,3-dien-2-yldimethyl(phenyl)silane (13.1.2b)[156] was also prepared in a similar
synthetic sequence as described above in multi-gram scale (Scheme-13.1.1). This diene is in
liquid form and has some practical disadvantages such as handling, storing etc. when compared
Si
O
O O1
2
3
4
Si1
2
3
4
5
6
ClMg
Mga-e f g
i
h 11.3.2b 13.1.2a
O
N
O
O
Si
13.1.2b
O
SiO
O
O
K
13.1.2c
(85%, yellow liq.) (91%, yellow solid)
(65%, white solid)
(98%, brown liq.)
1
2
3
4
5
6
123
4
8
7
96
5
5'
7
a) Dibromoethane, THF, r.t; b) ZnCl2, THF, r.t; c) THF, ∆, 15min; d) Chloroprene, dibromoethane, THF, dropwise, 30min; e) ∆,
45min; f) i. Canula transfer of (9.1.21) to (EtO)3SiCl in THF; ii. ∆, 1h; g) Triethanolamine, cat. KOH, THF, ∆, 1h; h) i. Canula transfer
of (9.1.21) to Me2PhSiCl in THF, r.t; ii. ∆, overnight; i) i. Catechol, KOH, THF; ii. ∆, 1h;
9.1.21
Scheme - 13.1.1: Synthesis of 2-alkyl(aryl)siloxy buta-1, 3-dienes
83 to other dienes. At room temperature, Dienes 13.1.2a and 13.1.2c show no signs of
decomposition over a period of a few weeks.
All the silyl butadienes (11.3.2b, 13.1.2a-c) were structurally confirmed and fully
characterized by 1D and 2D NMR techniques (Appendix C). In case of diene 13.1.2b, presence of
a NOESY peak (Appendix C) from H1↔H3 confirms the compound is in the s-trans
conformation in solution. Whereas the dienes 13.1.2a and 13.1.2c do not show any distinct
NOESY peaks in between H1↔H4 and H3↔H1 (Appendix C), we conclude that the
conformational changes (S-cis ↔ S-trans) are too fast to observe as there is no observable peak
broadening even at low temperature (-60 ⁰C) in solution (Appendix C).
Structure of the diene 13.1.2a was confirmed by both NMR and X-ray analysis (Figure-
13.1.2). In NMR analysis (solution), even at lower temperatures (-60 ⁰C) we were not able to
assign any one of the two conformers (S-cis or S-trans) due to the absence of NOE peak in
between H1↔H4 and/or H3↔H1. Whereas the X-ray analysis of the transparent, needle like
crystals (Appendix D) proved to be unusual in that there are three independent molecules per
asymmetric unit. Two of the molecules in this unit had s-trans diene like torsion angles where as
the third molecule had an s-cis like diene torsion angle. The C(17)-C(18)-C(19)-C(20) torsion
angle and Si(1)-C(18)-C(19)-C(20) torsion angle in the ‘S-trans’ conformation was -178.5 (3)⁰ and
2.1 (4)⁰ respectively. Whereas the C(37)-C(38)-C(39)-C(40) torsion angle and Si(3)-C(38)-C(39)-
C(40) in the ‘S-cis’ conformation were found to be 36.3 (4)⁰ and -144.3 (3)⁰ respectively. The
N→Si bond (dative) length for the ‘S-trans’ conformer was determined as 2.158 (1)⁰A, whereas
the other conformer, ‘S-cis’ was found to be 2.144⁰A which is in agreement with structural
trends found for such systems.[159] In general, if the length of the dative bond increases, the
silicon-carbon (sp2) bond decreases and vice versa. The C(18)-Si(1) bond length is found as 1.896
(0.12)⁰A which is slightly longer than the regular Si-C sp2 bond.[160] This change can be attributed
84 to the dπ-pπ interactions between the neighbouring π-system and the silicon center
(hyperconjugation). The pseudo-pentacoordinate distorted trigonal bipyramidal geometry which
is apparent in the title diene (13.1.2a) is common to silatranes. The angle at C(18)-Si(1)-N(1) is
almost linear i.e. 178.10 (9.8)⁰, while the O(12)-Si(1)-O(11), O(12)-Si(1)-O(13), O(11)-Si(1)-O(13)
angles are 118.59 (8)⁰, 117.96 (8)⁰ and 119.39 (8)⁰ respectively. Also the C(18)-Si(1)-O angles are
much closer to optimal trigonal bipyramidal (90⁰) than tetrahedral geometry (109.5⁰).
Silyl diene (13.1.2c) crystallizes with potassium coordinated THF molecules (Figure 13.1.3)
and the structure was inferred by both NMR and X-ray crystallography (Appendix E). In the case
of silyl diene-13.1.2c, both in solution (NMR) and solid (crystals) phase only one conformer was
detected. Solid-state structure of this compound (only ‘S-trans’) was determined by X-ray
crystallography, and the C(14)-C(13)-C(15)-C(16) torsion angle and Si(1)-C(13)-C(15)-C(16)
torsion angle were -176.7 (8)⁰ and 3.7 (11)⁰ respectively.
85
In order to test our assumptions about the reactivity of dienes based on the ligands around
the silicon, we carried out a model study in between the 2-silylbutadienes using N-
phenylmaleimide (9.1.4b) as the dienophile. This study gave us the support for our prediction as
dienes 13.1.2a and 13.1.2c were totally consumed within 30 min at room temperature. It is
noteworthy that due to the volatility of the diene 9.1.20 (bp 47-51 ⁰C, 12mm), we took the mass
of the recovered dienophile (9.1.4b) after the reaction to calculate the mass of the reacted
diene in the reaction (Scheme-13.1.2).
[Si]
N
O
O
Ph+THF, r.t
N
[Si]
O
O
Ph
% Conversion % Yield
(by 1HNMR)
[Si] = (Me)3Si (9.1.20)a N/A 13.1.1a (35 %)b, c, e
= (EtO)3Si (11.3.2b) ~2 % 13.1.1bb, d, e
= N(CH2CH2O)3Si (13.1.2a) 100 % 13.1.1c (98 %)b, e
= (C6H4O2)2Si K (13.1.2c) 100 % 13.1.1d (99 %)b, e
= [Ph(Me2)]Si (13.1.2b) 100 % 13.1.1e (98 %)f
a highly volatile ≥25 °C; bafter 30 min; cbased on recoverd 9.1.4b; dnot isolated; er.t; 30 min; f90 °C, 4 h.
9.1.4b 13.1.1a-e
30 min
Scheme - 13.1.2: Comparative study of reactivities of various silyldienes
86 All of the isolated cycloadducts were characterized by 1H NMR and 13C NMR. Cycloadduct
13.1.1d coordinated with a molecule of CH3CN was also characterized by X-ray diffraction
studies (Appendix F). The Si–sp2C bond length in between Si(1)–C(13) is slightly shorter
(1.874(4)⁰A) compared to the starting diene (1.889(5)⁰A). As like in the diene, the cycloadduct
also has O–Si–O bond angles between the adjacent oxygens in 85–88⁰ range. The overall
geometry around the silicon is significantly distorted square-based pyramid with bond angles
133.91(15) and 163.90(15) in between O(4)–Si–O(1) and O(3)–Si–O(2) respectively (Figure
13.1.4).
Diene 13.1.2a and 13.1.2c were treated with N-phenylmaleimide at 0 ⁰C, spontaneous
cycloaddition was noticed with diene 13.1.2c compared to 13.1.2a. When we compared these
most reactive silicon-substituted dienes, 13.1.2a and 13.1.2c with known, reactive dienes such
as Danishefsky’s diene, 13.1.2d (1-methoxy-3-trimethylsiloxy-1,3-butadiene)[161] for relative
Figure 13.1.4: Crystal Structure of Catechol Silyl Substituted Cycloadduct, 13.1.1d
(Coordination with a molecule of CH3CN was shown)
87 reactivity, we found that silatrane diene 13.1.2a reacted with N-phenylmaleimide at 0 ⁰C with
kobs of 3.7 × 10-2 min-1 and t1/2 of 18.8 min where as 13.1.2d reacted under identical conditions
with kobs of 2.1 × 10-2 min-1 and t1/2 of 33 min. Whereas, the (buta-1,3-dien-2-yl)triethoxysilane
(11.3.2b) had not reached t1/2 by 10 hours under these conditions. This data suggests that the
diene 13.1.2a is almost twice as reactive as diene 13.1.2d (Appendix G).
Single-point energy, semiempirical (AM1) calculation of HOMO energies for a number of
dienes, while constraining the 1,3-dienyl dihedral angle at 0⁰, were also calculated using
SPARTAN 2.0. 1,3-Butadiene (13.1.2g), 2-methoxybutadiene (13.1.2e), and 13.1.2d have HOMO
energies of -9.35, -9.09 and -8.82 eV, respectively. Dienes 11.3.2b, 13.1.2a and 13.1.2c have
HOMO energies of -9.21, -7.87 and -5.04 eV, respectively. These observations are consistent
with our observations that 11.3.2b is less reactive than 13.1.2d where as 13.1.2a is more
reactive than 13.1.2d and less reactive than diene 13.1.2c (Figure 13.1.5).
According to Houk’s Rule, the difference between the values of both termini needs to be
higher to achieve better selectivity. If this is true, then diene 13.1.2a needs to be more selective
than 13.1.2c, but we had noticed that diene 13.1.2c was more selective than 13.1.2a when
treated with citraconic anhydride, 9.1.4c. The observed selectivities could result not only
because of the electronic nature of silicon but also due to steric interactions of the ligands on
Si
O
O O
Si
MeO
(7) (8)
O
N
O
OSi
(10)
O
SiO
O
O
K
(9)
TMSO
OMe
(19)
Me
(20) (21) (22)
0.564
0.564
0.666
0.416
0.574
0.434
0.595
0.5190.541
0.571
0.591
0.550
0.080
0.063
0.562
0.550
-9.21 -9.35-9.09-8.82 -9.22HOMO(eV)
-7.87 -5.04-9.24
0.030 0.000.2500.140 0.076C1-C4 0.041 0.0170.012
Figure - 13.1.5: Semi-empirical MO calculations
88 silicon. In order to compare the reactivities between dienes 13.1.2a and 13.1.2c, we used the
less reactive, symmetrical and unsymmetrical dienophiles such as citraconic anhydride (9.1.4c)
and ethyl-2-propenoate (9.1.4d) under identical reaction conditions (Table-13.1.2).
Diene 13.1.2a reacted with 9.1.4c to produce 2.0:1.0 mixture of para:meta regioisomers
(13.1.3a: 13.1.3b) in 77.5% isolated yields. Whereas, diene 13.1.2c reacted under slightly milder
conditions to produce a 4.8:1 mixture with the same dienophile in 78.2% isolated yield. The
same trend of this diene (13.1.2c) for being slightly reactive over the other diene 13.1.2a was
also noticed when reacted with ethyl acrylate, 9.1.4d. Although these dienes are similar in
reactivity and regioselectivity to previously reported thermal Diels-Alder reactions of 2-phenyl-
Diene Dienophile % Conversion
(by 1H NMR)
% Yield Regioisomeric Ratio
13.1.2ai 100% 78% 2.0 : 1.0 (13.1.3a:13.1.3b)
13.1.2cii
9.14c
100% 78% 4.8 : 1.0 (13.1.4a:13.1.4b)
13.1.2aiii 100% 99% 4.0 : 1.0 (13.1.3c:13.1.3d)
13.1.2civ
9.14d
100% 94% 3.6 : 1.0 (13.1.4c:13.1.4d)
iTHF, 120 ⁰C, 48 h; iiTHF, 80 ⁰C, 36 h, iiiTHF, 150 ⁰C, 90 h, ivTHF, 90 ⁰C, 28 h
Table - 13.1.2: Comparitive reactivity studies of silylbuta-1, 3-dines
89 1,3-butadiene,[162, 163] they have the advantage of converting the cycloadducts to a variety of
aryl substituted cycloadducts by using cross-coupling chemistry. The regio- and stereochemistry
of the minor and major isomers were originally postulated using NOESY data (Appendix H)
which showed strong NOEs between the –CH3 and both the ring junction H and one of the two
diasterotopic H’s on the CH2 α to the alkene C–H for both 13.1.3a and 13.1.4a. This assignment
was further confirmed by X-ray crystallography (Figure 13.1.6, Appendix I).
The regiochemistry of the major isomer (13.1.3c, 13.1.4c) from the reactions with 9.1.4d was
established by the presence of a strong HMBC cross peak in between C2 and H4 (Appendix J).
From all these experimental and theoretical studies, it was inferred that diene 13.1.2c is more
reactive and selective among all of the other 2-silylbutadienes prepared so far.
The reactivity studies carried out, to date, gave insight about choosing the right diene for the
catalytic reactions to be studied. For example, dienes 11.3.2b and 13.1.2b which are mild in
reactivity with 9.1.4b at room temperature could serve as the starting diene to use in catalytic
reactions with transition metals either to use at room temperature and/or moderate heating
conditions as the silyl dienes do not interfere with the transition metal catalyzed cycloaddition
90 reactions. Whereas dienes 13.1.2a and 13.1.2c can serve as the reacting partners in
developing one-pot reaction protocols via sequential, tandem, and domino reactions.
13.2) Synthesis of terminal substituted 2-silyl-1,3-dienes. To validate the exo- selectivity, we
have prepared dienes such as 13.2.4a and 13.2.4b in 3 steps starting from the propargylic
alcohols by the following modified procedure.[164] Allenic alcohols (13.2.2a, 13.2.2b) were
prepared by homologation of the corresponding propargylic alcohols (13.2.1a, 13.2.1b) using
the literature procedure (Scheme-13.2.1).[165]
Synthesis of Trimethyl[(E)-4-phenyl-1,3-butadien-2-yl]silane (13.2.4a). Allenic alcohol 13.2.2a
was used to prepare 1-phenyl-3-bromo-1,3-diene (13.2.3a) by the addition-elimination reaction
using LiBr in acetic acid.[166, 167] The bromodiene (13.2.3a) was used in making the silyldiene
(13.2.4a) according to the modified procedure outlined below (Scheme-13.2.2)
MgMg∗
1
2
3
4
Ph CC
OH CH2
+ LiBr
~ 80 % (using Et2O)~ 40 -55 % (using pentane)
13.2.2a
OH
OH
13.2.3a
Scheme - 13.2.2: Synthesis of trimethyl[-(E )-4-phenyl-1,3-butadien-2-yl-]silane (13.2.4a)
H
Ph
Br
Cl Mg TMS+ +
Reaction conditions: a) CH3COOH, 50 °C, 40 min; b) i. I2 in THF,r.t; ii. dibromoethane in THF, r.t; iii. r.t→ 0 °C
c) TMSCl; d) 13.2.3a in THF, dropwise, 30 min; e) 0 °C→ r.t, overnight
Ph
TMS
13.2.4a
(85%) yellowish-brownliquid
a bc
d, e
91
HOC C CH2
CC CH2
TMS
~50% yield(unoptimized)
13.2.4b
Scheme - 13.2.3: Synthesis of (1-cyclohexenylvinyl)trimethylsilane (13.2.4b)
Br
13.2.2b 13.2.5b 13.2.3b
H H
AcO
MgMgCl Mg TMS+
Reaction conditions: a) acetic anhydride, pyridine, DMAP, 40 °C, overnight; b) 15.0 mol% Pd(OAc)2, LiBr,
CH3COOH, 40 °C, overnight; c) i. I2 in THF,r.t; ii. dibromoethane in THF, r.t; iii. r.t 0 °C
d) TMSCl, dropwise; e) 13.2.3b in THF, dropwise, 30 min; f) 0 °C r.t, overnight
a bcd
e, f
Synthesis of (1-Cyclohexenylvinyl)trimethylsilane (13.2.4b). Allenic alcohol (13.2.2b) was
acetylated (13.2.5b) and treated with LiBr in the presence of cat. Pd(OAc)2 to give 2-
bromodiene (13.2.3b),[165] as a light yellow oil. The diene (13.2.3b) was used in the Grignard
reaction according to the procedure outlined below (Scheme-13.2.3) to give the diene, 13.2.4b
in moderate yields.
Synthesis of siloxacyclopentene containing 1,3-dienes (13.2.4c-f). In 2004, Clark and Woerpel
reported the reaction of a silacyclopropene with a protected enynol to produce a
siloxacyclopentene containing a silicon substituent at the terminal position of a 1,3 diene moiety
as non-separable regioisomers in moderate yields (Scheme-9.2.10).[117] This diene was shown to
react with N-phenylmaleimide (9.1.4b) under drastic reaction conditions (130 ⁰C, 6-9 d) to yield
the cycloadducts with mediocre selectivity. Also in 2004 Lee and co-workers reported the
synthesis of a number of siloxacycles that are part of a 1,3-diene unit via a
condensation/metathesis strategy using alkenyl alcohols and alkynyl silanes.[118] These reported
dienes may not undergo Diels-Alder reactions due to the steric interactions in between the
substituents on C2 and C3 of the diene moiety (Scheme-9.2.11). We had simultaneously been
92
13.2.7a: R1, R2 = Me (94%)
13.2.7b: R1 = Ph, R2 = Me (96%)
13.2.7c: R1, R2 = iPr (89%)
MeMe
Si
HR2
R1
Me
H
Si
O
R1
R2
Reaction Conditions: i. BuLi; ii. R1R2Si(H)Cl; iii. (HCHO)n, KOtBu (10 mol%), THF
Scheme-13.2.4: Synthesis of siloxacyclopentene containing 1,3-dienes from pentenyne
13.2.6a
using a combination of the Tamao-Ito[168] and Lee protocols[169] to make siloxacyclopentenes
which could participate in intermolecular Diels-Alder reactions.
We first prepared several enynyl silanes (Scheme-13.2.4) in excellent yields from pentenyne
(13.2.6a) and tried to convert them into siloxacyclopentene containing 1,3 dienes using Lee’s
alkynylation-hydrosilylation sequence.[169] Unfortunately, we only recovered enynyl silanes
(13.2.7a-c) from these reactions.
Based on the reports involving the preparation of oxasilacyclopentanes containing vinyl
substituents,[129, 133, 169-173] we first prepared (Scheme-13.2.5) stable diisopropylsiloxy substituted
enynes (13.2.9a, 13.2.9c-e)[174, 175] via condensation of methylbutenyne (13.2.6b) with carbonyl
compounds and then converted them into diisopropylsiloxacyclopentene containing 1,3-diene
(13.2.4c) using a base catalyzed trans-hydrosilylation protocol reported in literature.[169]
93
Under the same reaction conditions reported above, using cyclohexenylethyne (13.2.6c)
with carbonyl compounds yielded the diisopropylsiloxacyclopentene containing 1,3-diene,
13.2.4d in moderate yields (Scheme-13.2.6).
Due to the instability of dimethylsiloxy substituted enynes (13.2.8g-h), they are generated in-
situ using the Tamao-Ito protocol[176] and converted into siloxacyclopentene containing dienes
(13.2.4e,f). These dienes were found to be stable for weeks in bench-top conditions (Scheme-
13.2.7).
All of these dienes were thoroughly characterized and structurally proven that they are in S-
trans conformation in solution by 1D and 2D NMR techniques. Having these dienes in hand we
have performed several Diels-Alder reactions. 2-Methyl substituted dienes 13.2.4c and 13.2.4e
both reacted completely with N-phenylmaleimide (9.1.4b) within 24-36 h at 90 ⁰C (Scheme-
13.2.8). The dimethylsiloxy substituted diene (13.2.4e) provides endo adduct (13.2.11b)
HSi
OMe
Me
Me
Me
13.2.4d (75%)
O
Si
Me
MeHMe
Me
R2R1
OH
a, b cd
13.2.8e-f13.2.9e (53%)
13.2.6c
13.2.8e = R1 = R2 = H (93%)
13.2.8f = R1 = H; R2 = Ph (97%)
Reaction conditions: a) i. THF, -78 °C; ii. nBuLi; iii. -78°C → 0 °C, 1 h
b) i. 0 °C → -78 °C; ii. aldehyde/ketone; iii. -78 °C → r.t, overnight
c) i. hexanes, 0 °C; ii. DMAP, NEt3; iii. iPr2Si(H)Cl in hex, 10 min; iv. 0 °C → r.t, overnight
d) i. THF; ii. waterbath; iii. KOtBu in THF; iv. r.t, 1 h.
Scheme - 13.2.6. Synthesis of diisopropylsilyloxy substituted enyne (13.2.9e) and siloxacyclopentene containing 1,3-diene (13.2.4d)
94
exclusively. Whereas the more bulky diisopropyl siloxy diene 13.2.4c provides both the exo
and endo cycloadducts (13.2.10a and 13.2.10b respectively) in almost equal proportions. This
outcome can be rationalized by unfavorable steric interactions between the N-phenyl and the
isopropyl groups in the electronically favored endo transition state.
Cyclohexenyl substituted dienes 13.2.4d and 13.1.4f proved much less reactive in thermal
Diels-Alder reactions and only start to show traces of Diels-Alder cycloadducts after 40-50 h of
heating at 90 ⁰C. While we were publishing our preliminary results in this area, Halvorsen and
Roush[177] reported their findings in synthesis of siloxacyclopentenes containing pendant
dienophiles and demonstrated that they could be used in intramolecular Diels-Alder reactions
which were followed by protiodesilylation.[177] In their study, they reported that
siloxacyclopentene constrained nonatrienes participated in thermal Diels-Alder reactions with
little stereoselectivity whereas these substrates participated in Lewis acid catalyzed
intramolecular Diels-Alder (IMDA) reactions through endo transition states to produce
perhydroindene cycloadducts with high stereoselectivity.[177] They found that siloxacyclopentene
constrained decatrienes participated in thermal or Lewis acid catalyzed cycloadditions through
endo transition states to produce octahydronaphthalenes with high stereoselectivity.
The stereochemistry of the Diels-Alder cycloadducts 13.2.10a,b and 13.2.11b were assigned
using a combination of COSY, HMQC, and HMBC to make all the 1H and 13C assignments followed
95
by NOESY to assign stereochemistry (Appendix K). In the cis isomers that arise from the endo
transition states (13.2.10b, 13.2.11b), one of the diastereotopic H5 protons exhibits NOE to both
H8a and H8b whereas the other H5 does not exhibit NOE to either of those protons (Figure-
13.2.1).
13.3) Diels-Alder/Cross Coupling Reactions: We have demonstrated that it is possible to effect
Hiyama cross coupling reactions of these silicon substituted Diels-Alder cycloadducts.[178]
Silatrane substituted cycloadduct (13.1.1c) was treated with a wide variety of aryl iodides
substituted with electron donating and electron withdrawing substituents (13.3.1a-j) in the
presence of Pd(OAc)2, PPh3, and TBAF (Scheme-13.3.1).
Si
O
N
O
O
HH
HH
H
Me
Me
Me
Me 1
23
4 56
7
8b
9
1011
12
13
14 15
165a
8a8
Me
Figure-13.2.1: Schematic Representation of Cycloadduct Stereochemistry
(Endo adduct, 13.2.10b in benzene-d6 (other protons were not shown for clarity))
96
Most of these cross coupling reactions proceeded in excellent yield with the exception of
the use of 2-iodo anisole (13.3.1b), 2-iodothiophene (13.3.1i), and 3-iodo benzonitrile (13.3.1j)
which produced cross coupled cycloadducts in more moderate yields around 50-60%.
All these cross coupled products were characterized by 1H and 13C NMR techniques and the
cross coupled product from 2-fluoro-iodobenzene (13.3.2e) was also characterized by X-ray
crystallography (Figure 13.3.1, Appendix L).
We tried these cross coupling conditions with a bis catechol silyl substituted cycloadduct
such as 13.1.1d and p-iodotoluene (13.3.1k) and we isolated the desired cross coupled product
(13.3.2k) in moderate yields (Scheme-13.3.2). Screening of various catalysts and optimization of
reaction conditions are still in needed to use this class of cycloadducts.[139]
97 We have also looked very briefly at the possibility of using these dienes in one pot
sequential reaction sequences (Scheme-13.3.3) rather than the two pot Diels-Alder cross
coupling sequences described above. The first attempt to do transmetallation/Diels-Alder/cross
coupling by treating 13.1.2a with 9.1.4b, 13.2.2a, and TBAF in the presence of Pd(II) and CuI, just
yielded the cross coupling product of the silyl diene, 2-phenyl-1,3-butadiene (13.3.4).[179] The
implication of this experiment is that transmetallation/oxidative addition/reductive elimination
couldn’t be intercepted by the Diels-Alder reaction under these conditions. A less ambitious
transmetallation/Diels-Alder/protonolysis scheme did yield some Diels-Alder product (13.3.5)[180,
181] from a one pot reaction.
14) Future Research. Having the promising results from our preliminary investigation on
using various silyl substituted 1,3-dienes (11.3.2b, 13.1.2a-c, 13.2.4c,e) with dienophiles such as
N-phenylmaleimide (9.1.4b), citraconicanhydride (9.1.4c) and ethylvinyl ketone (9.1.4d), our
research in this area could be extended to study the stero- and regio- chemical outcome of
other highly substituted dienophiles (Scheme-14.1.1) with silyl dienes (11.3.2b, 13.1.2a-c,
13.2.4a-f) prepared in our labs.
98
We have also shown that the silyl substituted cycloadducts could participate in cross
coupling reactions effectively, however more work should be done in optimizing reaction
conditions for using bis catechol substituted silyl cycloadducts as cross coupled reacting
partners. Based on the exemplary reactions involving a domino reaction sequence (Scheme-
13.3.3), screening of various additives to transmetalate dienyl silanes onto transition metal
should be carried out in order to increase the stereo (Exo) and regio chemistry of the
cycloadducts involving unsymmetrical dienophiles as per the proposal outlined earlier (Scheme-
12.2).
Based on our results so far on the cycloaddition reactions of silyl dienes (Table-2), we
envision that the dienes-11.3.2b and 13.1.2b could be used in room temperature catalytic
reactions whereas the other dienes-13.1.2a and 13.1.2c could be used in low temperature
catalytic reactions in order to prevent the competing reactions that may occur due to the
reactivity of the silyl diene alone.
The literature[148-150] reveals that starting with a Pt(II) catalyst would be advantageous in
achieving the goals of the proposed work. Since there is no reduction of Pt(II) to Pt(0) in any
part of the catalytic cycle, we can rule out the possibility of PATH – C in the proposed Scheme-
12.2. The advantages of using a Pt(II) catalyst are summarized here:
O
PhO
O
O
O
O
N
O
O
OO
O
O N
O
O
9.1.4d 9.1.4f 9.1.4g 9.1.4h9.1.4b 9.1.4c
Scheme - 14.1.1: Various substituted dienophiles and cross-coupling reagents
Mono substituted dienophiles: Ethylvinyl ketone (9.1.4d); Methyl propiolate (9.1.4f)
Di substituted dienopiles: N-Phenylmaleimide (9.1.4b); Dimethylfumerate (9.1.4e)
Tri substituted dienophiles: Citraconicanhydride (9.1.4c); Phenylmaleic anhydride (9.1.4g)
Tetra substituted dienophiles: N-Phenyl-2,3-dimethylmaleimide (9.1.4h)
Cross-coupling aryl compound, where X = I, Br, OTf
Ph Ph
CO2Me
MeO2C
9.1.4e
X
99
Scheme - 14.1.2: Proposed catalytic cycle for domino/tandem Diels-Alder and cross-coupling reactions
Flouride source = CsF, TBAF etc.; R = Alkoxy, Alkyl, Aryl; M = Pt(II)
SiR3TBAF
R3(F)Si
M(II)Ln2X2
Si
F
RR
RX
MeO2C
Diels-Alder
CO2Me
CO2Me
CO2Me
M(II)Ln
X Ln
Ar-X
CO2Me
CO2MeM(IV)
Ar
reductive
elimination
catalyst
regeneration
oxidative
addition
X
X
Ln
NBu4
NBu4
M(II)Ln
LnX
CO2Me
CO2MeM(IV)
Ar
X
X
Ln
MeO2C
MeO2C Ar
reductive
elimination
catalyst
regeneration
Ar-X
oxidative
addition
M(IV)
Ar
X
Ln
CO2Me
MeO2C
M(IV)Ar
Ln
X
CO2Me
CO2Me
Diels-Alder
trans-cis
isomerization
X
X
trans-
metalation
PATH - B
trans-
metalation
PATH - A
i) Stable Pt(II) catalysts [bi (or) tridentate] can be prepared easily.[149, 153, 182]
ii) These complexes were known to form Pt(II) ↔ Pt(IV) complexes readily in the
reaction conditions.
iii) Reductive elimination (through a five coordinate intermediate) is slow compared to
the oxidative addition. From these assumptions, we refine the Scheme-12.2, and
propose the plausible mechanism for future research in developing the catalytic
pathway as follows (Scheme-14.1.2).
The stable Pt(II) catalysts can be prepared by a direct (aromatic) C-H activation using
PtCl2(dmso)2[149, 182, 183] with an external base. The representative example for the synthesis of
the Pt(II) catalyst (14.1.1a-d) is outlined in Scheme-14.1.3.
100
Very recently, Buchwald and co-workers[184-186] published their work in preparation of
stable, highly reactive palladocycles (14.1.1e-i) to facilitate C-N cross-coupling reactions using
aryl chlorides in low temperature oxidative additions (Scheme-14.1.4). These types of catalysts
could be used in lieu of platinocylces (Scheme-14.1.3) when the oxidative additions of platinum
catalysts are in question due to electron rich nature of the metal.
If needed, other terminal substituted silyldienes (other than 13.2.4a-f) could be prepared
easily according to the plan outlined hereunder.
tBu
O
NMe2H2N+tBu
N NMe2
H
K2PtCl6 + H2O DMSO+(excess)
[PtCl2(dmso)2]+
4
32
1
65
7
N
Pt
Cl
8
9N
Scheme - 14.1.3: Synthetic route for the preparation of Pt(II) catalysts
N
H
tButBu
[PtCl2(dmso)2]
NaOAc, MeOH, ∆∆∆∆
PPh3
CH2Cl2
Pt
NDMSO
Cl
tBu
Pt
NPPh3
Cl
N
Pt N Me
Me
Cl
CltBu
H
C-H
Activation
NPt
N
Cl
Me
Me
tBu14.1.1a14.1.1b
14.1.1c 14.1.1d
PCy2R1
R2
R5
R4
R3
XPhos (e), R1, R2 = iPr
SPhos (f), R1 = OMe; R2 = H
RuPhos (g), R1 = OiPr; R2 = H
BrettPhos (h), R1, R2, R3 = iPr, R4, R5 = OMe
DavePhos (i), R1, R3, R4, R5 = H; R2 = NMe2
(MeCN)2PdCl2 TMEDA+a
NMe2
PdCl2
Me2N
b
NMe2
PdMe2
Me2N
c
PdNMe2
Cl L
L =
Reaction conditions: a) MeCN, r.t; b) MeLi, MTBE, 0 °C;c) 2-(2-chlorophenyl)ethanamine, ligand (L), MTBE, 55 °C
14.1.1e-i
Scheme - 14.1.4: Synthesis of palladocycle catalyst
101 14.1) From allenic acetates/allenic carboxylates: Alkoxysilyl dienes (14.1.3a,b) can be
prepared by allylic substitution of the allenic acetates (13.2.5a,b)[165] allenic carboxylates
(13.2.5c-e)[187] using (aminosilyl)lithiums (Scheme-14.1.5) which can be prepared in two
steps by using a Tamao protocol.[188-191]
14.2) From halodienes: Alkoxysilyl dienes (Scheme-14.1.6) can also be prepared by SN2'
reaction of the silylanions with halodienes (13.2.3a,b). During the Hiyama coupling
reactions, selective reductive elimination of the vinyl groups even in the presence of aryl
and alkyl groups were reported.[192]
Si
Scheme - 14.1.6: Proposed reaction pathway for synthesis of alkoxysilyldienes
Reaction conditions: a) Et2NH, NEt3, THF, 0 C, overnight; b) Li (granular),
THF, 0 C, 4h; c) 13.2.3a/13.2.3b in THF; d) EtOH, r.t, overnight
a b c dPh SiCl3 Si
Ph
Et2N NEt2Cl
Si
Ph
Et2N NEt2Li
NEt2Ph
NEt2
R
Si OEtPh
OEt
R
14.1.2a,b 14.1.3a,b
R = Ph (14.1.3a)= Cyclohexyl (14.1.3b)
R = Ph (14.1.2a)= Cyclohexyl (14.1.2b)
102
Scheme - 14.1.8: Enyne cross-metathesis reaction for synthesis of trialkoxysilyldiene
R, R' = H or any group
EtO
SiEtO
EtO
R R'
N N
Ru
PhPCy3Cl
Cl
Mes Mes
14.1.5(Grubb's catalyst)
14.1.413.2.7d
cat. 14.1.5
ethylene atm.+
R
(EtO)3Si
14.1.6
14.3) Silylation of halodienes: Alkoxy silyl dienes (Scheme-14.1.7) can be prepared by
silylation of the halodienes (13.2.3a,b) with triethoxysilane in the presence of cat. Rh(I)[123]
or Pd(0).[137]
14.4) Enyne Cross-Metathesis: Intramolecular enyne cross-metathesis reactions (Scheme-
14.1.8) of triethoxysilylalkyne (13.2.7d)[193] with olefins (14.1.4) in the presence of second
generation Grubbs catalyst (14.1.5) results in the stereoselective synthesis of (E)-1,3-
disubstituted silylbutadienes (14.1.6).[194]
14.5) Kumada reaction: Triethoxysilyl diene (Scheme-14.1.9) can be prepared from the cross-
coupling reaction of halodienes (13.2.3a,b) with triethoxychlorosilane in the presence of
catalytic transition metals, Pd(II)105 or Ni(II).[195, 196]
14.1.1a,b
Scheme - 14.1.7: Synthesis of trialkoxysilyldienes by hydrosilylation of halodienes
R = Ph; X = Br (13.2.3a)
= Cyclohexyl; X = Br (13.2.3b)
R
X
H Si(OEt)3+
Rh (I)
or
Pd (0)
R
(EtO)3Si
R = Ph (14.1.3a)
= Cyclohexyl (14.1.3b)
103
Mg Mg* Cl Mg Si(OEt)3
Reaction conditions: a) i. I2 in THF,r.t; ii. dibromoethane in THF, r.t; iii. r.t → 0 °C;
b) i. catalytic Ni(II); ii.(EtO)3SiCl (65) in THF; c) 13.2.3a/b in THF, dropwise, 30 min
d) 0 °C → r.t, overnight
a b c, d
R
Si(OEt)3
R = Ph (14.1.3a)= Cyclohexyl (14.1.3b)
Scheme - 14.1.9: Synthesis of trialkoxysilyldiene by Kumuda reaction
14.6) Similar to silaxocyclopentene containing 1,3-dienes, 1,2-disubstituted halo dienes
(Scheme-14.1.10) could be prepared according to the literature procedure.[197-200] These
dienes can easily be converted in to the respective silyl dienes by using any of the silylation
protocols reported above.
Along with the development of the novel catalytic reaction pathway for exo- selectivity as
described in Scheme-14.2, this research can be extended to develop rhodium catalyzed
asymmetric 1,4-addition reactions as described below using the organosilanes prepared in our
labs.
Highly enantioselective asymmetric 1,4-addition reactions of trialkoxyorganosilanes with
α,β-unsaturated carbonyl compounds (ketones, esters and amides) using catalytic chiral
rhodium complexes were reported by Hayashi[201, 202] and Oi et al[203] (Scheme-14.1.11).
104
As per the literature on the asymmetric catalysis reactions[201-203] and from our results
described above, we propose that the same kind of analogy will work with the silyl dienes
prepared in our labs. The proposed mechanism is as follows (Scheme-14.1.12).
The success of this asymmetric catalytic cycle relies on conditions like the Diels-Alder
reaction of Rh-dienyl complex must be much faster than the cycloaddition reactions of silyldiene
(or) 1,4-additions of dienophile and α,β-unsaturated carbonyl compounds.
Scheme - 14.1.11: Rhodium-catalyzed asymmetric 1,4-addition of organosilanes
XRh BINAP
X = BF4 orOH
Ar Si(OR)3
H2O SiX(OR)3
Where R = Me, Et or H
Rh BINAPAr
O
R"
R'
R"
O
R'
Ar
RhBINAP
H2O
R'
Ar O
R"
transmetalation
1,4-addition
hydrolysis
catalystregeneration
105
15) Conclusion. We have prepared stable alkoxy and alkyl silyl buta-1,3-dienes that are
both in oil and solid, crystalline forms and have shown that they would undergo the
cycloaddition reactions to give the cycloadducts with improved regio selectivities. These silyl
dienes and their cycloadducts act as facile cross-coupling partners in Hiyama cross-coupling
reactions. Along with these silyl-1,3-butadines, various other silyl dienes that are terminally
substituted were also prepared for stereoselectivity studies through two to three step
procedures from enynes and other halo-substituted 1,3-dienes. The
dimethylsilyloxycyclopentene containing 1,3-dienes were prepared via a one pot, two step
sequence from enynols. These dienes were shown to undergo Diels-Alder reactions with a
higher preference for the production of trans cycloadducts from the sterically more bulky
diisopropylsiloxy substituted dienes. Very recently our group[204] prepared several other
substituted silyl dienes by using ene-yne cross metathesis as projected under future research
(14.4).
Due to time constraints, we were only able to study a very few domino reactions in order to
develop new reaction sequences that involve successive transmetallation, Diels-Alder and cross-
coupling reactions to yield the cross-coupled cycloadducts. But in the reactions we carried out,
we were only able to isolate the cross-coupled diene when Pd (II), silyl diene (11.3.2b), N-
phenylmaleimide, iodobenzene and TBAF were taken together. From this we assumed that
transmetallation/oxidative addition/reductive elimination could not be intercepted by the Diels-
Alder reactions under these reactions conditions. Also, in another case we isolated a Diels-Alder
product formed from a less ambitious transmetallation/Diels-Alder/protonolysis reaction
sequence.
106
16) Experimental: General. The 1H NMR spectra were recorded by using a Bruker
Avance 500MHz spectrometer and Bruker Avance 300MHz spectrometer operating at
500.13MHz and 300.13MHz respectively. 13C NMR spectra were recorded on a Bruker Avance
300MHz spectrometer and Bruker Avance 500MHz spectrometer operating at 75.48MHz and
125.77MHz respectively. Chemical shifts were reported in parts per million (δ) relative to
trichlorofluoromethane (Cl3CF, 0.00 ppm), tetramethylsilane (TMS, 0.00 ppm), dimethyl
sulfoxide (DMSO, 2.50 ppm) or chloroform (CDCl3, 7.26 ppm). Coupling constants (J values) were
reported in hertz (Hz), and spin multiplicities were indicated by the following symbols: s
(singlet), d (doublet), t (triplet), q (quartet), p (pentet), s (sixtet), h (heptet) and m (multiplet).
All elemental analyses were carried out by Atlantic Microlabs Inc., GA. High resolution mass
spectrometric (HRMS) analyses were carried out at the Duke Mass Spectrometric Facility,
Durham, NC. Flash chromatography was performed using thick-walled glass chromatography
columns and “Ultrapure” silica gel (Silicycle Ind., Canada, 40 – 63 μm). Vacuum filtrations were
carried out with the aid of microanalysis vacuum filter apparatus and Millipore filter
membranes.
All reactions were carried out under an inert atmosphere unless otherwise noted. The
common reaction solvents were distilled distilled by using the centrally located solvent
dispensing system developed by J.C. Meyer.[76] Tetrahydrofuran (THF), diethyl ether (Et2O), and
dichloromethane (CH2Cl2) were degassed with argon and then passed through two 4 x 36 inch
columns of anhydorous neutral A-2 alumina (8 x 14 mesh; activated under a flow of Ar at 350 °C
for 3 hr) to remove water. Toluene (PhMe) was degassed with Ar and then passed through one 4
x 36 inch column of Q-5 reactant (activated under a flow of 5% hydrogen/nitrogen at 250 °C for
3 hrs) to remove oxygen then through one 4 x 36 inch column of anhydrous alumina to remove
107
water. Hexanes were distilled over CaH2 before use. Silyl reagents were either purchased
from Aldrich Chemicals or Gelest Inc. Deuterated solvents were purchased from Cambridge
Isotopes and used as received. All the transition-metal catalysts were purchased from Strem
Chemicals, stored in a desicator and used without any further purification. Chloroprene (1a) was
purchased from Pfaltz & Bauer and stored at -78 ºC. All other chemicals were purchased from
Sigma-Aldrich and used as received.
3-Cyclohexenylprop-2-yn-1-ol (13.2.2b),[80] pent-3-en-1-yne,[77] 4-methylpent-4-en-2-yn-1-
ol,[17, 78, 79] 1-[(E)-3-bromobuta-1,3-dienyl]benzene (13.2.3a),[205, 206] and (2-bromoallylidene)
cyclohexene (13.2.3b)[165] and other 2-silyl substituted 1,3-butadienes were prepared according
to the reported literature.[207, 208]
General Procedure for Synthesis of Enynylsilane (13.2.7a-c). Enynylsilanes were prepared
according to a similar procedure reported by Maifeld et al.[169] To a stirring colorless clear
solution of enyne (1.05eq) in THF (20 mL) at -78 ⁰C using dry ice/acetone bath, nBuLi (1.10eq,
1.6M solution in hexanes) was added in ~ ca. 15 min. The yellow-brown, clear reaction mixture
was stirred for 15 min. at this temperature, then chlorosilane (1.0eq) taken in THF (15 mL) was
added dropwise over a period of 15 min. After stirring at this temperature for 30 min, cold bath
was removed and the white cloudy reaction mixture brought to room temperature and stirring
continued for overnight. The white thick reaction mixture was diluted with Et2O (50 mL) and
quenched with aqueous NH4Cl (100 mL) solution. Aqueous layers washed with Et2O (2 × 25 mL)
and the combined organic layers were washed with brine (100 mL), dried over MgSO4. After
removal of volatiles, the crude product was subjected for purification.
Dimethyl(pent-3-en-1-ynyl)silane [13.2.7a]. According to general procedure mentioned above
using pent-3-en-1-yne (3.14 g, 47.5 mmol), nBuLi (32.0 mL, 51.2 mmol), and
108
dimethylchlorosilane (4.34 g, 45.9 mmol) resulted compound 13.2.7a as colorless clear
liquid after purification by using flash chromatography (5.54 g, 44.7 mmol, 94%): Rf 0.39 (100%
hexanes); Major isomer(trans): 1H NMR (500 MHz,
CDCl3) δ 6.22 (dq, J = 15.9, 6.8 Hz, 1H, H−4),
5.50−5.54 (m, 1H, H−3), 4.16 (h, J = 3.8 Hz, 1H, H−6),
1.77 (dd, J = 6.8, 1.8 Hz, 3H, H−5), 0.23 (dd, J = 3.8,
1.3 Hz, 6H, H−7); 13C NMR (300 MHz, CDCl3) δ 141.6 (C−4), 110.7 (C−3), 105.4 (C−2), 89.3 (C−1),
18.6 (C−5), −3.0 (C−7); Minor Isomer(cis): 1H NMR (500 MHz, CDCl3) δ 6.04 (dq, J = 10.8, 6.8 Hz,
1H, H−4), 5.46−5.50 (m, 1H, H−3), 4.20 (h, J = 3.8 Hz, 1H, H−6), 1.89 (dd, J = 6.8, 1.8 Hz, 3H, H−5),
0.26 (dd, J = 3.8, 1.3 Hz, 6H, H−7); 13C NMR (300 MHz, CDCl3) δ 140.5 (C−4), 110.0 (C−3), 103.2
(C−2), 95.8 (C−1), 16.1 (C−5), −2.9 (C−7); Regio isomer ratio 1.0:1.2 (cis to trans, based on 1H
NMR).
Methyl(phenyl)(pent-3-en-1-ynyl)silane [13.2.7b]. Pent-3-en-1-yne (1.03 g, 15.6 mmol), nBuLi
(10.2 mL, 16.3 mmol) and
methyl(phenyl)chlorosilane (2.22 g, 14.2
mmol) was used as mentioned in general
procedure. The resulted crude product
was subjected to column chromatography
yielded compound 13.2.7b as colorless, clear liquid (2.66 g, 14.3 mmol, 96%): Rf 0.33 (100%
hexanes); Major isomer(cis): 1H NMR (500 MHz, CDCl3) δ 7.65−7.77 (m, 2H, H-9), 7.37−7.50 (m,
3H, H−10, 11), 6.13 (dq, J = 10.9, 6.9 Hz, 1H, H−4), 5.61−5.65 (m, 1H, H−3), 4.80 (q, J = 3.7 Hz, 1H,
H−6), 1.98 (dd, J = 6.9, 1.9 Hz, 3H, H−5), 0.57 (d, J = 3.7 Hz, 3H, H−7); 13C NMR (300 MHz, CDCl3) δ
141.2 (C−4), 134.3 (C−9), 133.9 (C−8), 129.7 (C−11), 128.0 (C−10), 110.0 (C−3), 104.9 (C−2), 93.6
(C−1), 16.2 (C−5), −3.5 (C−7), −3.6 (C−7); Minor isomer(trans) (diagnostic peaks): 1H NMR (500
109
MHz, CDCl3) δ 6.35 (dq, J = 15.7, 6.9 Hz, 1H, H−4), 5.58−5.61 (m, 1H, H−3), 4.75 (q, J = 3.7 Hz,
1H, H−6), 1.84 (dd, J = 6.9, 1.9 Hz, 3H, H−5) , 0.54 (d, J = 3.7 Hz, 3H, H−7); 13C NMR (300 MHz,
CDCl3) δ 142.2 (C−4), 110.6 (C−3), 107.1 (C−2), 87.1 (C−1), 18.7 (C−5); Anal. calcd for C12H14Si: C,
77.35; H, 7.57. Found: C, 77.09; H, 7.68. Regio isomer ratio 1.2:1.0 (cis to trans, based on 1H
NMR).
Diisopropyl(pent-3-en-1-ynyl)silane [13.2.7c]. Pent-3-en-1-yne (0.826 g, 12.5 mmol), nBuLi (8.0
mL, 12.8 mmol) and diisopropylchlorosilane (1.74 g, 11.5 mmol) was used according to the
general procedure resulted the crude
compound as colorless oil. After purification by
flash chromatography, compound 13.2.7c was
isolated as colorless, clear liquid (1.84 g, 10.2
mmol, 89%): Rf 0.69 (100% hexanes); Major isomer(trans): 1H NMR (300 MHz, CDCl3) δ 6.26 (dq, J =
15.8, 6.8 Hz, 1H, H−4), 5.53−5.60 (bm, 1H, H−3), 3.73 (bs, 1H, H−6), 1.79 (dd, J = 6.8, 1.7 Hz, 3H,
H−5), 0.93−1.16 (m, 14H, H−7,8); 13C NMR (300 MHz, CDCl3) δ 141.5 (CH), 140.4 (CH), 110.9 (CH),
110.2 (CH), 106.7 (C), 104.5 (C), 92.5 (C), 85.9 (C), 19.1 (CH), 18.7 (CH), 18.6 (CH3), 18.5 (CH3),
18.48 (CH3), 18.2 (CH3), 10.9 (CH3); Minor isomer(cis) (diagnostic peaks): 1H NMR (300 MHz, CDCl3)
δ 6.04 (dq, J = 10.9, 6.8 Hz, 1H, H−4), 5.48−5.53 (bm, 1H, H−3), 3.78 (bs, 1H, H−6), 1.91 (dd, J =
6.8, 1.7 Hz, 3H, H−5); Regio isomer ratio 1.0:1.3 (cis to trans, based on 1H NMR).
General Procedure for Synthesis of Propargylic Alcohols (13.2.8b-e). Propargylic alcohols were
prepared by the addition of lithium acetylide to the corresponding aldehyde as follows.[79] To a
solution of alkyne (1.0 eq) taken in THF (75 mL) at -78 ⁰C was added with nBuLi (1.1eq, 1.6M
solution in hexanes) in ~ca. 30 min. The resulted clear orange solution was raised to 0 ºC and
stirred for additional 1 h and the flask was again cooled back to -78 ºC. After the addition of
respective electrophile (1.25eq), stirring was continued for overnight at room temperature
110
followed by quenching with saturated aqueous NH4Cl (100 mL). Aqueous layers were
extracted with Et2O (3 × 50 mL), followed by washing of combined organics with saturated
aqueous NaCl solution (100 mL), and rotovapped to nearly dryness. The crude product was
further purified by flash chromatography.
4-Methyl-1-phenylpent-4-en-2-yn-1-ol [13.2.8b]. 2-Methylbut-1-en- 3-yne (3.45 g, 52.2 mmol),
nBuLi (36.0 mL, 57.6 mmol) and benzaldehyde (6.64 g, 62.6 mmol) were used
according to the general method mentioned above. Purification of the
resulting clear yellow-brown crude yielded the pure product as clear yellow-
brown oil (8.44 g, 49.0 mmol, 94%): Rf 0.72 (hexanes/Et2O, 4:1); 1H NMR (300
MHz, CDCl3) δ 7.49−7.69 (m, 2H, H−8), 7.30−7.49 (m, 3H, H−9, 10), 5.58 (d, J =
6.2 Hz, 1H, H−1), 5.37 (bs, 1H, H−5), 5.28 (p, J = 1.5 Hz, 1H, H−5), 2.43 (d, J = 6.2 Hz, 1H, −OH),
1.93 (bs, 3H, H−10); 13C NMR (300 MHz, CDCl3) δ 140.6 (C−7), 128.6 (C−9), 128.3 (C−10), 126.6
(C−8), 126.1 (C−4), 126.6 (C−5), 87.8 (C−2/3), 87.7 (C−2/3), 64.9 (C−1), 23.3 (C−6); HRMS calcd
for C12H12O (M+)172.0888, found 172.0885.
2,5-Dimethylhex-5-en-3-yn-2-ol [13.2.8c]. Using 2-methylbut-1-en- 3-yne (3.45 g, 52.2 mmol),
nBuLi (36.0 mL, 57.6 mmol) and acetone (3.89 g, 67.0 mmol) resulted 13.2.8c
as brown crude reaction mixture which upon purification by flash
chromatography yielded the pure product as clear yellow oil (2.232 g, 18.0
mmol, 33%): Rf 0.22 (hexanes/Et2O, 4:1); 1H NMR (500 MHz, CDCl3) δ 5.21 (s, 1H, H−6), 5.15 (s,
1H, H−6), 2.48−2.93 (bs, 1H, −OH), 1.82 (as, 3H, H−7), 1.49 (as, 6H, H−1, 8); 13C NMR (300 MHz,
CDCl3) δ 126.3 (C−5), 121.7 (C−6), 92.8 (C−3), 83.2 (C−4), 65.4 (C−2), 31.4 (C−1, 8), 23.4 (C−7);
HRMS calcd for C8H12O (M+)124.0888, found 124.0885.
3,6-Dimethylhepta-1,6-dien-4-yn-3-ol [13.2.8d]. The title compound was prepared according to
general method above by using 2-Methylbut-1-en-3-yne (1.73 g, 26.1 mmol), nBuLi (18.0 mL,
111
28.8 mmol) and but-3-en-2-one (2.19 g, 31.3 mmol). Crude product was purified by flash
chromatography (2.23 g, 16.4 mmol, 63%): Rf 0.28 (hexanes/Et2O, 4:1); 1H NMR (300 MHz,
CDCl3) δ 6.00 (dd, J = 17.1, 10.2 Hz, 1H, H−2), 5.49 (dd, J = 17.1, 0.7 Hz, 1H,
H−1trans), 5.25−5.32 (m, 1H, H−7), 5.18−5.25 (m, 1H, H−7), 5.11 (dd, J = 10.2,
0.7 Hz, 1H, H−1cis), 2.24 (s, 1H, −OH), 1.88 (as, 3H, H−8), 1.56 (s, 3H, H−9); 13C
NMR (300 MHz, CDCl3) δ 142.0 (C−2), 126.2 (C−6), 122.1 (C−7), 113.5 (C−1),
89.9 (C−4/5), 85.9 (C−4/5), 68.5 (C−3), 29.9 (C−9), 23.4 (C−8);
3-Cyclohexenyl-1-phenylprop-2-yn-1-ol [13.2.8e]. Using 1-ethynylcyclohex-1-ene (1.99 g, 18.7
mmol), 1.6M nbutyllithium (14 mL, 22.4 mmol) and benzaldehyde (2.43 g, 22.9 mmol) resulted
yellow-brown crude reaction mixture which upon purification by
flash chromatography yielded the pure product as light yellow
colored oily substance (3.84 g, 18.1 mmol, 97%): Rf 0.47
(hexanes/Et2O, 2:1). Spectral data is consistent with earlier reported data.[209]
General Procedure for Syntheses of Enynyloxysilanes (13.2.9a-e). Enynyloxysilanes were
prepared by the following method anologous to the procedure reported.[173, 210] Alkenynol
(1.0eq), dimethylaminopyridine (10 mol%), and triethylamine (1.01eq) were added at 0 ⁰C to a
250 mL, single-neck round bottom flask having hexanes (100 mL). The flask was charged with
stirbar and an additional funnel. After stirring to homogenate the reaction mixture for a while,
chlorosilane taken in hexanes (10 mL) were added dropwise over a period of 20 min during
which the reaction mixture slowly turns to cloudy white suspension. Later the reaction mixture
was brought to ambient temperature and stirring continued for overnight. The thick white
reaction mixture was filtered through a pad of silica using sintered funnel, and the silica pad was
washed with hexanes (2 × 20 mL). After removal of volatiles, the crude product was purified by
using flash chromatography.
112
(4-Methylpent-4-en-2-ynyloxy)diisopropylsilane [13.2.9a]: 4-methylpent-4-en-2-yn-1-ol
(2.0 g, 20.8 mmol), dimethylaminopyridine (0.252 g, 2.10 mmol), triethylamine (2.13 g, 21.0
mmol) and diisopropylchlorosilane (3.14 g, 20.8 mmol) was used
according to the general procedure. The resulted clear, light yellow
colored crude compound was purified by flash chromatography
resulted 3.91 g (18.6 mmol, 90%) of pure product as clear colorless solution: Rf 0.82
(hexanes/Et2O, 9:1); 1H NMR (500 MHz, CDCl3) δ 5.28 (bs, 1H, H−5), 5.22 (bs, 1H, H−5), 4.49 (s,
1H, H−1), 4.21 (s, 1H, H−7), 1.88 (s, 3H, H−6), 0.74−1.37 (m, 14H, H−8, 9); 13C NMR (300 MHz,
CDCl3) δ 126.5 (C−4), 121.8 (C−5), 86.5 (C−3), 86.3 (C−2), 54.3 (C−1), 23.2 (C−6), 17.3 (C−9), 17.2
(C−9), 12.3 (C−8); Anal. calcd for C12H22OSi: C, 68.51; H, 10.54. Found: C, 68.32; H, 10.73.
(4-Methyl-1-phenylpent-4-en-2-ynyloxy)diisopropylsilane [13.2.9b]. Using 4-methylpent-4-en-
2-yn-1-ol (1.61 g, 9.36 mmol), dimethylaminopyridine (0.117 g, 0.975 mmol), triethylamine (1.00
g, 9.92 mmol) and diisopropylchlorosilane (1.31 g, 8.68 mmol)
according to the general procedure, resulted the crude product as
clear, light yellow colored compound. Upon purification by flash
chromatography resulted 0.742 g (2.59 mmol, 30%) of pure product
as light yellow colored solution: Rf 0.85 (hexanes/Et2O, 4:1); Major
isomer: 1H NMR (300 MHz, CDCl3) δ 7.43−7.58 (m, 2H, H−8), 7.18−7.41 (m, 3H, H−9, 10), 5.64 (s,
1H, H−1), 5.30 (bs, 1H, H−5), 5.16−5.23 (m, 1H, H−5), 4.36 (s, 1H, H−11), 1.85−1.88 (m, 3H, H−6),
0.86−1.18 (m, 14H, H−12, 13); 13C NMR (300 MHz, CDCl3) δ 141.2 (C−7), 128.3 (C−9), 127.8
(C−10), 126.4 (C−8), 121.9 (C−5), 88.3 (C−2), 87.5 (C−3), 67.4 (C−1), 23.20 (C−6), 17.4 (C−13),
17.35 (C−13), 17.27 (C−13), 12.52 (C−12), 12.45 (C−12); Minor isomer (diagnostic peaks): 1H
NMR (300 MHz, CDCl3) δ 5.55 (s, 1H, H−1), 5.34 (bs, 1H, H−5), 5.23−5.27 (m, 1H, H−5), 1.88−1.92
10
11 12
13
OSi
H1
2
34
5
6
7
8
9
H
(13.2.9b)
113
(m, 3H, H−6); 13C NMR (300 MHz, CDCl3) δ 140.7 (C−7), 128.5 (C−9), 126.6 (C−10), 126.3
(C−8), 122.5 (C−5), 64.9 (C−1), 23.24 (C−6);
(2,5-Dimethylhex-5-en-3-yn-2-yloxy)diisopropylsilane [13.2.9c]. 2,5-Dimethylhex-5-en-3-yn-2-
ol (13.2.8c) (1.77 g, 14.3 mmol), triethylamine (1.69 g, 15.3 mmol), dimethylaminopyridine
(0.180 g, 1.50 mmol) and diisopropylchlorosilane (1.92 g, 12.7 mmol)
were resulted 13.2.9c as colorless clear oil (2.23 g, 9.36 mmol, 74%)
after purification by flash chromatography: Rf 0.90 (hexanes/Et2O, 4:1);
1H NMR (500 MHz, CDCl3) δ 5.24 (as, J = 0.9 Hz, 1H, H−6), 5.19 (p, J = 1.4
Hz, 1H, H−6), 4.38 (at, J = 1.4 Hz, 1H, H−9), 1.87 (t, J = 1.4 Hz, 3H, H−7), 1.52 (s, 6H, H−1, 8),
1.01−1.07 (m, 14H, H−10, 11); 13C NMR (300 MHz, CDCl3) δ 126.6 (C−5), 121.2 (C−6), 92.9 (C−3),
84.2 (C−4), 67.4 (C−2), 32.4 (C−1, 8), 23.4 (C−7), 17.6 (C−11), 17.5 (C−11), 12.6 (C−10); HRMS
calcd for C14H27OSi (M+H)+ 239.1831, found 239.1819.
(3,6-Dimethylhepta-1,6-dien-4-yn-3-yloxy)diisopropylsilane [13.2.9d]. 3,6-dimethylhepta-1,6-
dien-4-yn-3-ol (13.2.8d) (1.52 g, 11.2 mmol), triethylamine (1.20 g, 11.9 mmol),
dimethylaminopyridine (0.153 g, 1.28 mmol) and
diisopropylchlorosilane (1.66 g, 11.0 mmol) were used according to
the general procedure. The resulted brown, clear crude product was
purified by column chromatography resulted the title compound
(13.2.9d) as clear colorless solution (2.64 g, 10.5 mmol, 96%): Rf 0.91 (hexanes/Et2O, 4:1); 1H
NMR (300 MHz, CDCl3) δ 5.92 (dd, J = 17.0, 10.2 Hz, 1H, H−2), 5.44 (d, J = 17.0 Hz, 1H, H−1), 5.28
(bs, 1H, H−7), 5.22 (p, J = 1.5 Hz, 1H, H−7), 5.07 (d, J = 10.2 Hz, 1H, H−1), 4.36 (s, 1H, H−10), 1.89
(s, 3H, H−8), 1.56 (s, 3H, H−9), 0.95−1.14 (m, 14H, H−11, 12); 13C NMR (300 MHz, CDCl3) δ 142.6
(C−2), 126.4 (C−6), 121.6 (C−7), 112.8 (C−1), 89.9 (C−4), 86.9 (C−5), 70.5 (C−3), 31.6 (C−9), 23.3
114
(C−8), 17.6 (C−12), 17.55 (C−12), 17.53 (C−12), 12.7 (C−11), 12.6 (C−11); HRMS calcd for
C15H26OSi (M+) 250.1753, found 250.1744.
(3-Cyclohexenylprop-2-ynyloxy)diisopropylsilane [13.2.9e]. 3-Cyclohexenylprop-2-yn-1-ol
(13.2.8e) (1.24 g, 12.9 mmol), triethylamine (1.30 g, 12.9 mmol), dimethylaminopyridine (0.152
g, 1.27 mmol) and diisopropylchlorosilane (1.92 g, 12.7 mmol) was
used to yield compound 13.2.9e (1.68 g, 6.71 mmol, 53%) as colorless,
clear oily substance after purification by flash chromatography: Rf
0.85 (hexanes/Et2O, 4:1); 1H NMR (500 MHz, CDCl3) δ 6.08 (h, J = 1.8
Hz, 1H, H−5), 4.48 (s, 2H, H−1), 4.20 (s, 2H, H−10), 1.98−2.17 (m, 4H, H6−9), 1.49−1.71 (m, 4H,
H6−9), 0.96−1.12 (m, 14H, H−11, 12). 13C NMR (300 MHz, CDCl3) δ 134.8 (C−5), 120.3 (C−4), 87.1
(C−2/3), 84.4 (C−2/3), 54.3 (C−1), 29.0 (C6−9), 25.6 (C6−9), 22.2 (C6−9), 21.5 (C6−9), 17.3 (C−12),
17.2 (C−12), 12.3 (C−11);
2-Trialkylsiloxy Substituted 1,3-butadienes and Their Synthesis.
General Procedure: An oven-dried 100 mL 2-neck round-bottom flask equipped with a magnetic
stir bar, addition funnel and reflux condenser was charged with magnesium (1.6 eq) followed by
the addition of dibromoethane (11.0 mol %) in THF (5 mL). After stirring ~ca. 5 min (initiation of
magnesium activation can be noticed by its silver color and ethane gas liberation), 3.0 mol % of
anhydrous ZnCl2 in THF (5 mL) was added. This mixture was added with additional THF (30 mL)
and resulted in a whitish-grey solution which was brought to gentle reflux over a period of 15
min. Chloroprene (in 50 % xylenes) (1.0 eq) and dibromoethane (23.0 mol %) in THF (25 mL) was
added drop-wise to the refluxing reaction mixture over 30 min. After the addition, refluxing was
continued for another 45 min. The greenish-grey colored Grignard solution was transferred by
canula into a 250 mL, one-neck round-bottomed flask containing alk(aryl)oxychlorosilane (0.95
eq) in THF (25 mL) at room temperature. The reaction mixture was refluxed (1 h), poured into
115
0.5M HCl solution (100 mL) and extracted with pentane (2 × 75 mL). The combined colorless
clear organic layers were washed successively with 0.5M HCl (75 mL) and water (2 × 100 mL).
After drying over MgSO4, the solvent was removed under reduced pressure to yield 2-
substituted silyl diene with xylenes as a colorless liquid. This compound was subjected to
fractional vacuum distillation to remove xylenes and then purified by flash chromatography.
Synthesis of (buta-1,3-dien-2-yl)dimethyl(phenyl)silane (13.1.2b). Chloroprene (4.58 g, 51.7
mmol) and phenyldimethylchlorosilane (8.03 g, 47.1 mmol) were used according to the general
procedure above to yield a light yellow colored crude product (14.4 g) as a
mixture of diene, 13.1.2b and xylenes. The crude product was subjected to
fractional distillation at reduced pressure (20 mm, 45 ⁰C) resulted in diene,
13.1.2b (7.77 g) as a brown colored liquid, which was further purified by flash
chromatography (100% pentanes) to yield the title compound as a light yellow colored liquid in
pure form (8.36 g, 44.4 mmol, 97%): Rf 0.63 (100% pentanes); 1H NMR (500 MHz, CDCl3) δ
7.49−7.55 (m, 2H, H−7), 7.31−7.37 (m, 3H, H−8, 9), 6.46 (dd, J = 17.7, 10.9 Hz, 1H, H−3), 5.88 (d, J
= 3.2 Hz, 1H, H−1), 5.51 (d, J = 3.2 Hz, 1H, H−1), 5.10 (d, J = 17.7 Hz, 1H, H−4trans), 5.00 (d, J = 10.9
Hz, 1H, H−4cis), 0.43 (s, 9H, H−5); 13C NMR (300 MHz, CDCl3) δ 147.6 (C−2), 141.1 (C−3), 138.2
(C−6), 133.9 (C−7), 130.4 (C−1), 129.0 (C−9), 127.8 (C−8), −2.3 (C−5); HRMS calcd for C12H16Si
(M+) 188.1021, found 188.1020.
Synthesis of (buta-1,3-dien-2-yl)triethoxysilane (11.3.2b).[106, 158, 211] Chloroprene (5.04 mL,
0.026 mol) and triethoxychlorosilane (5.0 mL, 0.025 mol) were used according to the general
procedure above to yield a colorless crude product as a mixture of diene, 11.3.2b and xylenes
(1.7:1.0). This compound can be used in the ligand exchange reactions to make compounds
13.1.2a and 13.1.2b or can be purified by fractional distillation under controlled pressure. The
title compound (11.3.2b) distills as a colorless liquid (4.55 g, 0.021 mmol, 85%) after the xylenes
116
Si
O
O O
12
3
4
5
6
(11.3.2b)
(55 ºC – 60 ºC, 4 mm). 1H NMR (300 MHz, CDCl3) δ 6.45 (dd, J = 17.5, 10.7 Hz, 1H, H−3), 5.90
(d, J = 3.4 Hz, 1H, H−1), 5.81 (d, J = 3.4 Hz, 1H, H−1), 5.54 (d, J = 17.5 Hz, 1H, H−4trans), 5.14 (d, J =
10.7 Hz, 1H, H−4cis), 3.84 (q, J = 7.0 Hz, 6H, H−5), 1.23 (t, J = 7.0 Hz,
9H, H−6); 13C NMR (300 MHz, CDCl3) δ 141.1 (C−2), 140.4 (C−3),
133.4 (C−1), 117.9 (C−4), 58.6 (C−5), 18.1 (C−6); Anal. calcd for
C10H20O3Si: C, 55.53; H, 9.33. Found: C, 55.93; H, 9.09.
Synthesis of (buta-1,3-dien-2-yl)silatrane (13.1.2a).[212] A one neck round bottomed flask (100
mL) fitted with a reflux condenser was charged with THF solution (30 mL). To this flask,
triethanolamine (0.620 g, 4.16 mmol), compound 11.3.2b (1.0 g,
4.65 mmol) and a catalytic amount of KOH powder (5 mol%, 0.032
g, 0.058 mmol) were added successively. Under refluxing for 15
min. the reaction mixture turns clear orange-brown and then the
reaction mixture was cooled to room temperature and pentane (100 mL) was added to
precipitate the product. The light yellow solid was filtered and washed with ice-cold pentane (3
× 25 mL) to produce compound 13.1.2a (0.857 g, 3.77 mmol, 91 %) as a light yellow fluffy
powder. This compound was used to carry-out the cycloaddition reactions without any further
purification. X-ray quality crystals were prepared by the dual solvent crystallization technique
where the compound 13.1.2a was first dissolved in dichloroethane and then cyclohexane was
added for slow diffusion to produce 13.1.2a as white needles: m.p (neat) 104–106 ⁰C; 1H NMR
(300 MHz, CDCl3) δ 6.51 (dd, J = 17.5, 10.7 Hz, 1H, H−3), 5.74 (d, J = 4.5 Hz, 1H, H−1), 5.64 (d, J =
4.5 Hz, 1H, H−1), 5.42 (dd, J = 17.5, 2.3 Hz, 1H, H−4trans), 5.03 (dd, J = 10.7, 2.3 Hz, 1H, H−4cis),
3.86 (t, J = 5.8 Hz, 6H, H−5/6), 2.86 (t, J = 5.8 Hz, 6H, H−5/6); 13C NMR (300 MHz, CDCl3) δ 149.6
(C−2), 143.0 (C−3), 128.3 (C−1), 115.1 (C−4), 57.8 (C−5/6), 51.3 C−5/6); HRMS calcd for
117 C10H17O3SiN (M+) 227.0978, found 227.0979. Anal. calcd for C10H17O3SiN: C, 52.84; H, 7.54.
Found: C, 53.37; H, 7.67.
Synthesis of potassium bis(5,5’-benzenediolato)-(1,3-butadien-2-yl)silicate (13.1.2c).[139, 213]
Catechol (5.12 g, 0.046 mol) was dissolved in THF (60 mL) followed by the addition of compound
11.3.2b (5.0 g, 0.023 mol) and KOH powder (1.30 g, 0.023 mol) successively.
The reaction mixture was refluxed for one hour and the colorless solution
turned to clear dark orange. After reflux, the reaction mixture was brought to
room temperature, filtered to remove solid particles and pentane was added
to precipitate the product as a pale grayish white powder (7.77 g, 0.023 mol,
99%). Purification of the title compound was carried out by dissolving the product (5.72 g, 0.017
mol) in minimum quantity of hot THF, filtration and solidification by cooling the flask at -40 ⁰C
for 1 h ( 2.33 g, 6.93 mmol, 41%). The filtrate after rotovap (3.10 g, 9.23 mmol) was used again
for re-solidification (0.734 g, 2.18 mmol, 24%) as mentioned above resulted to improve the
overall product yield of the pure product (64%). For crystallographic studies, recrystallization
was carried out by dissolving the compound 13.1.2c taken up in a small test tube with a small
quantity of hot THF and cyclohexane was added carefully along the walls. This test tube was left
at room temperature for slow diffusion and the crystals grew out at the junction of the two
solvents as white needles: m.p (neat) 242 ⁰C (dec); 1H NMR (300 MHz, DMSO) δ 6.49−6.60 (m,
4H, H−6/7), 6.40−6.49 (m, 4H, H−6/7), 6.20 (dd, J = 17.5, 10.6 Hz, 1H, H−3), 5.29 (dd, J = 17.5, 2.3
Hz, 1H, H−4trans), 5.28 (d, J = 4.1 Hz, 1H, H−1), 5.18 (d, J = 4.1 Hz, 1H, H−1), 4.77 (dd, J = 10.6, 2.3
Hz, 1H, H−4cis); 13C NMR (300 MHz, DMSO) δ 151.3 (C−2), 150.3 (C−5), 142.2 (C−3), 123.5 (C−1),
117.3 (C−6/7), 114.5 (C−4), 109.7 (C−6/7). Anal. calcd for C16H13O4SiK: C, 57.14; H, 3.90. Found:
C, 56.96; H, 3.84.
118 2-Trialkyl(aryl)siloxy Terminal Substituted 1,3-Dienes and Their Synthesis.
General Procedure for Synthesis of Silyl Dienes 13.2.4a, 13.2.4b. Substituted silyl dienes
13.2.4a, 13.2.4b were prepared according to a procedure reported in the literature[214] with
slight modifications. Magnesium turnings (3.0eq) and iodine (4.0 mol%) were taken into a 2-
neck, 100 mL round-bottomed flask fitted with a reflux condenser, addition funnel and stir-bar.
After adding THF (2.0 mL) and stirring for ca~ 2 min, dibromoethane (15 mol%) in THF (5.0 mL)
was added at room temperature. After cessation of ethane gas evolution, the reaction flask was
cooled to 0 ºC using an ice-bath, and stirring continued for 10 min. Silylchloride (1.3eq) in THF
(10 mL) was added dropwise over 15 min. followed by dropwise addition of a mixture of 13.2.3a
or 13.2.3b (1.0eq) and dibromoethane (30 mol%) in THF (20 mL) over a period of 45 min. After
the addition of halodiene (13.2.3a or 13.2.3b), stirring was continued for 1h at 0 ºC and, then at
room temperature overnight. The reaction mixture was filtered through a pad of celite with
diethyl ether and then quenched with 0.6 M HCl (50 mL), and extracted with diethyl ether (3 ×
30 mL). The combined organic layers were washed with brine solution (2 × 50 mL), dried over
MgSO4 and volatiles were removed. The crude residue of the reaction mixture was purified by
flash chromatography.
Synthesis of Trimethyl[(E)-4-phenyl-1,3-butadien-2-yl]silane (13.2.4a). 1-[(E)-3-Bromobuta-1,3-
dienyl]benzene (13.2.3a) (1.99 g, 9.49 mmol) and trimethylsilylchloride (1.37 g, 12.6 mmol) were
used according to the general method above, producing the crude compound as
a dark brown liquid. The crude residue after purification by flash chromatography
(hexanes/ Et2O, 9:1) yields compound 13.2.4a as a brown-yellow oil (1.56 g, 7.73
mmol, 85%). Spectroscopic data was not reported earlier:[215, 216] Rf 0.15
(hexanes/Et2O, 9:1); 1H NMR (500 MHz, CDCl3) δ 7.43 (ad, J = 7.7 Hz, 2H, H-6), 7.34 (t, J = 7.7 Hz,
1H, H−7), 7.24 (t, J = 7.4 Hz, 1H, H−8), 6.94 (d, J = 16.5 Hz, 1H, H−3), 6.64 (d, J = 16.5 Hz, 1H,
119 H−4), 5.89 (d, J = 3.0 Hz, 1H, H−1), 5.53 (d, J = 3.0 Hz, 1H, H−1), 0.27 (s, 9H, H−9); 13C NMR
(300 MHz, CDCl3) δ 148.9 (C−2), 137.7 (C−5), 134.0 (C−3), 130.5 (C−4), 128.6 (C−1), 128.5 (C−7),
127.3 (C−8), 126.3 (C−6), 0.8 (C−9).
Synthesis of (1-cyclohexylideneprop-2-en-2-yl)trimethylsilane (13.2.4b). Chlorotrimethylsilane
(0.685 g, 6.30 mmol) and (2-bromoallylidene)cyclohexene (13.2.3b) (0.929 g, 4.64 mmol) were
used according to the above general procedure. The resulting dark brown
crude residue after purification by flash chromatography (hexanes/ Et2O, 15:1
→ 9:1) yielded compound 13.2.4b as a brown-yellow oil (0.483 g, 2.49 mmol,
47%): Rf 0.84 (hexanes/Et2O, 15:1); 1H NMR (500 MHz, CDCl3) δ 5.71 (s, 1H,
H−1), 5.40−5.49 (m, 2H, H−3), 2.10−2.23 (m, 4H, H−5,9), 1.54−1.60 (m, 4H, H−6,8), 1.41−1.50 (m,
2H, H−7), 0.07 (s, 9H, H−10); 13C NMR (300 MHz, CDCl3) δ 150.3 (C−2), 140.5 (C−4), 125.1 (C−3),
123.5 (C−1), 37.4 (C−5/9), 29.3 (C−5/9), 29.0 (C−6/8), 28.3 (C−7), 26.9 (C−6/8), −1.95 (C−10);
HRMS calcd for C12H22Si (M+) 194.1491, found 194.1489.
Genenral Procedure for Synthesis of Siloxacyclopentene Containing-1,3-Dienes (13.2.4c,
13.2.4d) by Potassium tert-Butoxide Catalyzed trans-Hydrosilylation of Enynyloxysilanes.[169]
Potassium tert-butoxide salt (10 mol%) taken in THF (10 mL) was added slowly ca. ~ 10 min to a
flask kept in water bath and having a solution of enynyloxysilane (13.2.9a, 13.2.9e) in THF (10
mL). Stirring was continued for 1h at ambient temperature, and the reaction mixture was
diluted with Et2O (50 mL) followed by quenching with saturated NH4Cl (100 mL) solution. The
organic layer was separated and aqueous layers were extracted with Et2O (3 × 50 mL). Combined
organic layers were washed with brine, dried over MgSO4. Volatiles were removed and crude
reaction mixture was subjected for purification by using flash chromatography and/or
chromatotron.
120 2,5-Dihydro-2,2-diisopropyl-3-(prop-1-en-2-yl)-1,2-oxasilole [13.2.4c]. (4-Methylpent-4-en-
2-ynyloxy)diisopropylsilane (13.2.9a) (1.66 g, 7.90 mmol) and KOtBu (0.092 g, 0.820 mmol) were
used according to the general procedure mentioned above. The resulted
light brown clear solution was subjected for column chromatography
yielded 1.19 g (5.67 mmol, 72%) of 13.2.4c as colorless, clear liquid: Rf 0.37
(hexanes/Et2O, 15:1); 1H NMR (500 MHz, CDCl3) δ 6.68 (t, J = 1.9 Hz, 1H,
H−4), 4.99 (s, 1H, H−9), 4.80 (s, 1H, H−9), 4.63 (dd, J = 1.9, 0.9 Hz, 2H, H−5), 1.94 (s, 3H, H−10),
1.09−1.19 (m, 2H, H−6), 1.04 (d, J = 7.3 Hz, 6H, H−7), 0.99 (d, J = 7.3 Hz, 6H, H−7); 13C NMR (300
MHz, CDCl3) δ 142.4 (C−4), 142.1 (C−8), 139.8 (C−3), 116.3 (C−9), 72.7 (C−5), 20.6 (C−10), 17.3
(C−7), 17.0 (C−7), 13.3 (C−6); Anal. calcd for C12H22OSi: C, 68.51; H, 10.54. Found: C, 68.24; H,
10.61.
3-Cyclohexenyl-2,5-dihydro-2,2-diisopropyl-1,2-oxasilole [13.2.4d]. Using (3-cyclohexenylprop-
2-ynyloxy)diisopropylsilane (13.2.4e) (0.715 g, 2.85 mmol) and KOtBu (0.037 g, 0.330 mmol)
resulted the crude product as colorless, clear liquid which upon flash
chromatography yielded the title compound as clear colorless liquid; Rf 0.45
(hexanes/Et2O, 15:2). The isolated compound was found having an impurity of
about ~20% with close Rf value, hence the compound was further purified by
using chromatotron (2.0 mm silica gel) (0.537 g, 2.14 mmol, 75%). 1H NMR (300 MHz, CDCl3) δ
6.56 (s, 1H, H−4), 5.57 (s, 1H, H−9), 4.61 (s, 1H, H−5), 2.17−2.26 (m, 2H, H−13), 2.03−2.16 (m, 2H,
H−10), 1.64−1.75 (m, 2H, H−12), 1.52−1.64 (m, 2H, H−11), 1.06−1.20 (m, 2H, H−6), 1.04 (d, J =
6.6Hz, 6H, H−7), 0.98 (d, J = 6.8Hz, 6H, H−7); 13C NMR (300 MHz, CDCl3) δ 140.3 (C−), 138.0 (C−4),
135.7 (C−), 128.9 (C−9), 77.8 (C−5), 26.2 (C−13), 26.0 (C−10), 22.8 (C−12), 22.4 (C−11), 17.4 (C−7),
17.1 (C−7), 13.4 (C−6)
Si
O1
2
3
4
5
67 8
H
910
(13.2.4c)
121
One-pot, Tandem Synthesis of Enynyloxysilanes (13.2.9g, 13.2.9h) and Their Potassium
tert-Butoxide Catalyzed trans-Hydrosilylation Reactions Using 1,1,3,3-
Tetramethyldisilazane:[169, 177] Alkenynol (13.2.9g or 13.2.9h) (1.0eq) was taken in a 50 mL,
round bottom flask kept in a water bath and attached with N2 inlet. After the slow addition of
tetramethyldisilazane (0.6eq) over ~ 5 min using syringe, water bath was removed and stirring
continued overnight at room temperature. Then volatiles were removed by rotovap and the
crude reaction mixture was dissolved in THF (10 mL), and flask was cooled in water-bath at
ambient temperature. The flask was purged with N2 for 2 min, then KOtBu (10 mol%) was added
in THF (3 × 5 mL) solution over a period of 10 min. After the addition, water bath was removed
and stirring continued for 1 h at room temperature. The reaction mixture was diluted with Et2O
(20 mL), followed by quenching with satd. NH4Cl (50 mL). Organic layer was separated and
aqueous layers were extracted with Et2O (3 × 20 mL). The combined organics were washed with
satd. NaCl solution (50 mL), dried over MgSO4 and volatiles were removed by rotovap. The crude
reaction mixture was purified by means of column chromatography or chromatotron.
2,5-Dihydro-2,2-dimethyl-3-(prop-1-en-2-yl)-1,2-oxasilole [13.2.4e]. Using 4-methylpent-4-en-
2-yn-1-ol (1.79 g, 18.6 mmol), 1,1,3,3-tetramethyldisilazane (1.50 g, 11.3 mmol) and KOtBu
(0.217 g, 1.93 mmol) according to the above general procedure resulted a clear
brown colored crude reaction mixture which upon purification by column
chromatography yielded 13.2.4e as clear colorless oil (2.01 g, 13.1 mmol, 70%):
Rf 0.68 (pentane/Et2O, 3:1); 1H NMR (500 MHz, CDCl3) δ 6.60 (as, 1H, H−4), 4.99
(s, 1H, H−8'), 4.82 (s, 1H, H−8''), 4.66 (s, 2H, H−5), 1.93 (s, 3H, H−9), 0.33 (as, 6H, H−6); 13C NMR
(300 MHz, CDCl3) δ 142.2 (C−3), 141.3 (C−7), 141.2 (C−4), 115.7 (C−8), 71.9 (C−5), 20.4 (C−9),
0.45 (C−6); HRMS calcd for C8H14OSi (M+) 154.0814, found 154.0813.
122
(3-Cyclohexenylprop-2-ynyloxy)dimethylsilane [13.2.9h]. 3-Cyclohexenylprop-2-yn-1-ol
(13.2.8e) (2.51 g, 26.1 mmol) and 1,1,3,3-tetramethyldisilazane (1.53 g,
11.5 mmol) were used according to the method mentioned above
resulted the title compound as brown clear liquid (3.92 g, 20.2 mmol,
77%). The crude reaction mixture was analyzed by 1H NMR to confirm
the product formation and used as in KOtBu catalyzed trans-hydrosilylation reaction.
3-Cyclohexenyl-2,5-dihydro-2,2-dimethyl-1,2-oxasilole [13.2.4f]. (3-Cyclohexenylprop-2-
ynyloxy)dimethylsilane (13.2.9h) (2.77 g, 14.3 mmol) and KOtBu (0.160 g, 1.43 mmol) were used
according to the general procedure. The brown oily crude reaction mixture was
purified by flash chromatography using hexanes/Et2O (6:1) as elutant resulted
13.2.4f as clear colorless oil (1.44 g, 7.39 mmol, 52%), which was further purified
by chromatotron (2.0 mm, silica gel) yielded 13.2.4f as colorless clear liquid in
pure form (1.02 g, 5.23 mmol, 71%): Rf 0.34 (hexanes/Et2O, 8:1); 1H NMR (300 MHz, CDCl3) δ
6.49 (s, 1H, H−4), 5.61 (s, 1H, H−8), 4.64 (s, 1H, H−5), 2.04−2.26 (m, 4H, H−9, 12), 1.51−1.77 (m,
4H, H−10, 11), 0.32 (s, 6H, H−6); 13C NMR (300 MHz, CDCl3) δ 142.6 (C−), 136.9 (C−), 135.2 (C−3),
128.8 (C−), 72.0 (C−5), 26.1 (C−), 22.6 (C−), 22.4 (C−), 0.74 (C−6); HRMS calcd for C11H18OSi (M+)
194.1127, found 194.1121.
General procedure for Diels-Alder reactions: The diene was dissolved in THF (2-5 mL) in a thick
walled micro wave tube charged with a mini stir-bar. After purging with nitrogen for 2 min,
dienophile was added and the tube was closed with an aluminum seal and the reaction was run
with continuous stirring at a stipulated time and temperature. The microwave tube was then
brought to room temperature and the seal was broken.
Synthesis of [(3a,4,7,7a-tetrahydro-2-phenyl-2H-isoindole-1,3-dione)-5-yl]silatrane (13.1.1c):
Diene (13.1.2a) (0.050 g, 0.220 mmol) and N-phenylmaleimide (0.080 g, 0.462 mmol) were used
H
Si
O1
23
4
56
7
8
910
11
12
(13.2.4f)
123
according to the general procedure for the cycloaddition reaction. After stirring 30 min. at
room temperature, the reaction mixture was filtered through a cotton plug and addition of
pentane (5 mL) to the filtrate resulted in cycloadduct (13.1.1c) as
white crystalline powder (0.086 g, 0.215 mmol, 98%): m.p (neat)
170–172 ⁰C; 1H NMR (500 MHz, CDCl3) δ 7.41 (t, J = 7.8 Hz, 2H,
H−12), 7.33 (t, J = 7.4 Hz, 1H, H−13), 7.29 (d, J = 7.4 Hz, 2H, H−11), 6.43 (t, J = 4.1 Hz, 1H, H−6),
3.77 (t, J = 6.0 Hz, 6H, H−8), 2.87−3.19 (m, 2H, H−3a, 7a), 2.81 (t, J = 6.0 Hz, 6H, H−9), 2.66 (dd, J
= 14.8, 4.0 Hz, 1H, H−4), 2.44−2.59 (m, 2H, H−4, 7), 2.28−2.40 (m, 1H, H−7); 13C NMR (300 MHz,
CDCl3) δ 179.7 (C−1/3), 179.6 (C−1/3), 142.8 (C−5), 134.3 (C−6), 132.5 (C−10), 128.8 (C−12),
128.1 (C−13), 126.8 (C−11), 57.5 (C−8), 51.0 (C−9), 39.81 (C−3a/7a), 39.76 (C−3a/7a), 27.6 (C−4),
24.4 (C−7); Anal. calcd for C20H24N2O5Si: C, 59.98; H, 6.04. Found: C, 60.34; H, 6.43.
Synthesis of potassium bis(8,8’-benzenediolato)-[(3a,4,7,7a-tetrahydro-2-phenyl-2H-isoindole-
1,3-dione)-5-yl]silicate (13.1.1d). Diene (13.1.2c) (0.30 g, 0.893 mmol) and N-phenylmaleimide
(0.246 g, 1.42 mmol) were used in the cycloaddition reaction
according to the general procedure. After stirring for 30 min at
room temperature, the product was seen precipitating out as a
white solid. Further precipitation was carried out by adding
pentane (5.0 mL) and quick filtration yielded cycloadduct (13.1.1d) as a white fluffy powder
(0.450 g, 0.884 mmol, 99%) : m.p (neat) 310 ⁰C (dec); 1H NMR (500 MHz, DMSO) δ 7.34−7.46
(m,3H, H−13,14), 6.85−6.97 (m, 2H, H−12), 6.54−6.64 (m, 4H, H−10), 6.45−6.54 (m, 4H, H−9),
6.23 (bs, 1H, H−6), 3.08−3.19 (m, 1H, H−3a), 2.98−3.07 (m, 1H, H−7a), 2.69 (dd, J = 14.9, 3.4 Hz,
1H, H−4), 2.33 (ddd, J = 15.1, 5.9, 4.0 Hz, 1H, H−7), 2.05−2.17 (m, 2H, H−4, 7); 13C NMR (500
MHz, DMSO) δ 179.4 (C−1), 178.9 (C−3), 150.5 (C−8/8’), 150.2 (C−8/8’), 142.8 (C−5), 135.5 (C−6),
132.6 (C−11), 128.6 (C−13), 127.9 (C−14), 127.2 (C−12), 117.4 (C−10), 117.1 (C−10), 109.8 (C−9),
8
9
10
1 2
3
4
N
O
O
5
6
7
3a
7a
11 12
13
SiO
O
O
N
(13.1.1c)
124
109.6 (C−9), 39.1 (C−3a/7a), 39.0 (C−3a/7a), 26.9 (C−4), 24.1 (C−7); Anal. calcd for
C26H20O6SiNK: C, 61.29; H, 3.96. Found: C, 61.03; H, 4.35. The unreacted dienophile (0.089 g,
0.514 mmol, 97%) was recovered after removal of the organics by using the rotovap.
Synthesis of 3a,4,7,7a-tetrahydro-5-[dimethyl(phenyl)silyl]-2-phenyl-2H-isoindole-1,3-dione
(13.1.1e). Diene (13.1.2b) (0.302 g, 1.60 mmol) and N-phenylmaleimide (0.103 g, 0.595 mmol)
were used according to the general procedure for the cycloaddition
reaction. After heating for 4h at 90 ⁰C, the reaction mixture was
filtered through a cotton plug and volatiles were removed by rotary
evaporation. The resulting yellow colored residue was purified by flash chromatography with
the excess diene eluting as a light yellow colored solution (0.151 g, 0.802 mmol, 78% recovery:
Rf 0.84, pentane/diethyl ether, 1:1) followed by the cycloadduct 13.1.1e as a colorless, clear
viscous liquid (0.204 g, 0.564 mmol, 98%): Rf 0.29 (pentane/diethyl ether, 1:1); 1H NMR (500
MHz, CDCl3) δ 7.41−7.54 (m, 4H), 7.29−7.41 (m, 4H), 7.09−7.20 (m, 2H, H−10), 6.34 (p, J = 3.2 Hz,
1H, H−6), 3.18−3.30 (m, 2H, H−3a, 7a), 2.71−2.88 (m, 2H, H−4,7), 2.22−2.36 (m, 2H, H−4,7), 0.36
(s, 3H, H−16), 0.35 (s, 3H, H−16); 13C NMR (300 MHz, CDCl3) δ 179.1 (C−1/3), 178.7 (C−1/3),
140.7 (C−5), 138.4 (C−6), 137.0 (C−12), 133.9 (CH), 132.0 (C−8), 129.2 (CH), 129.0 (CH), 128.4
(CH), 127.8 (CH), 126.3 (CH), 39.3 (C−3a/7a), 39.2 (C−3a/7a), 26.4 (C−4/7), 25.0 (C−4/7), -3.88
(C−16), -3.89 (C−16); HRMS calcd for C22H23NO2Si (M+) 361.1498, found 361.1490. Anal. calcd for
C22H23NO2Si: C, 73.10; H, 6.42. Found: C, 72.63; H, 6.38.
(5αS,8αS,8βS)-5,5a-dihydro-3,3-diisopropyl-4-methyl-7-phenyl-1H-[1,2]oxasilolo[4,3-e]
isoindole-6,8(3H,7H,8αH,8βH)-dione [13.2.10a] and (5αS,8αS,8βR)-5,5a-Dihydro-3,3-
diisopropyl-4-methyl-7-phenyl-1H-[1,2]oxasilolo[4,3-e]isoindole-6,8(3H,7H,8αH,8βH)-dione
[13.2.10b]. Compound 13.2.4c (0.496 g, 2.36 mmol), N-phenylmaleimide (0.201 g, 1.16 mmol)
were taken together according to above procedure and heated for 36 h. After removal of
125 volatiles, crude reaction mixture was disolved in CHCl3 (2.0 mL) followed by purification with
flash chromatography using hexanes/Et2O, 2:1 resulted elution of unreacted (excess) diene prior
to the cycloadducts. After elution of unreacted (excess) diene, polarity of the mobile phase was
increased (hexanes/Et2O, 1:1) to yield both the stereo isomers one after the other as in pure
form (0.382 g, 0.996 mmol, 86%).
Minor Isomer [13.2.10a]: After eluting the excess diene with hexanes/diethyl ether (2:1),
increasing the polarity yields (hexanes/Et2O, 1:1) stereo isomer – 13.2.10a as viscous clear liquid
almost in pure form (0.180 g, 0.469 mmol, 47%): Rf 0.61
(hexanes/Et2O, 1:1); 1H NMR (500 MHz, CDCl3) δ 7.47 (t, J = 7.4
Hz, 2H, H−15), 7.38 (t, J = 7.4 Hz, 1H, H−16), 7.29 (d, J = 7.4 Hz,
2H, H−14), 4.64 (dd, J = 10.0, 7.6 Hz, 1H, H−9), 3.90 (dd, J =
10.0, 8.6 Hz, 1H, H−9), 3.12 (ddd, J = 17.8, 9.5, 8.1 Hz, 1H, H−5a), 2.73 (dd, J = 15.9, 8.1 Hz, 1H,
H−5), 2.63 (t, J = 9.5 Hz, 1H, H−8a), 2.50−2.60 (m, 1H, H−8b), 2.22 (dd, J = 15.9, 10.0 Hz, 1H,
H−5), 1.96 (dd, J = 1.7, 1.0 Hz, 3H, H−12), 1.11−1.20 (m, 2H, H−10), 1.09 (d, J = 7.1, 3H, H−11),
1.02 (d, J = 7.4, 6H, H−11), 1.00 (d, J = 7.4, 3H, H−11); 1H NMR (300 MHz, C6D6) δ 6.82 (d, J = 7.9
Hz, 2H, H−14), 6.54 (t, J = 7.9 Hz, 2H, H−15), 6.40 (t, J = 7.9 Hz, 1H, H−16), 4.20 (dd, J = 9.8, 8.2
Hz, 1H, H−9), 3.29 (dd, J = 9.8, 8.8 Hz, 1H, H−9), 1.59−1.79 (m, 3H, H−5, 5a, 8a), 1.25 (t, J = 9.5 Hz,
1H, H−8b), 1.08 (dd, J = 17.7, 12.6 Hz, 1H, H−5), 0.93 (at, J = 1.3 Hz, 3H, H−12), 0.48 (d, J = 6.9
Hz, 3H, H−11), 0.36−0.46 (m, 2H, H−10), 0.43 (d, J = 5.4 Hz, 3H, H−11), 0.30−0.37 (m, 6H, H−11);
13C NMR (300 MHz, CDCl3) δ 178.3 (C−6), 177.9 (C−8), 143.9 (C−4), 131.7 (C−13), 131.0 (C−3),
129.1 (C−15), 128.5 (C−16), 126.3 (C−14), 72.7 (C−9), 43.8 (C−8a), 42.9 (C−8b), 39.7 (C−5a), 30.8
(C−5), 25.7 (C−12), 17.9 (C−11), 17.3 (C−11), 17.1 (C−11), 13.1 (C−10), 12.6 (C−10); HRMS calcd
for C22H30NO3Si (M+H)+ 384.1995, found 384.1979.
126 Major Isomer [13.2.10b]: Once 13.2.10a elution was completed, polarity of the mobile
phase was gradually increased to 100% Et2O, results the elution of other stereo isomer –
13.2.10b as major product in form of colorless clear viscous
liquid (0.202 g, 0.527 mmol, 53%): Rf 0.24 (hexanes/ Et2O, 1:1);
1H NMR (500 MHz, C6D6) δ 7.40 (d, J = 7.7 Hz, 2H, H−14), 7.12 (t,
J = 7.7 Hz, 2H, H−15), 6.97 (t, J = 7.7 Hz, 1H, H−16), 4.94 (dd, J =
10.0, 7.7 Hz, 1H, H−9), 4.31 (dd, J = 10.0, 9.0 Hz, 1H, H−9), 2.64 (d, J = 15.4 Hz, 1H, H−5),
2.36−2.52 (m, 2H, H−5a, 8a), 2.11−2.26 (m, 1H, H−8b), 1.68 (d, J = 2.6 Hz, 3H, H−12), 1.59−1.73
(m, 1H, H−5), 1.06 (d, J = 6.7 Hz, 3H, H−11), 1.01 (d, J = 5.9 Hz, 3H, H−11), 0.94 (d, J = 5.9 Hz, 3H,
H−11), 0.90 (d, J = 6.7 Hz, 3H, H−11), 0.88−1.12 (m, 2H, H−10); 1H NMR (500 MHz, CDCl3) δ 7.43
(t, J = 7.9 Hz, 2H, H−15), 7.35 (t, J = 7.9 Hz, 1H, H−16), 7.19 (d, J = 7.9 Hz, 2H, H−15), 4.65 (dd, J =
10.1, 8.2 Hz, 1H, H−9), 4.37 (dd, J = 10.1, 8.8 Hz, 1H, H−9), 3.25−3.40 (m, 2H, H−5a, 8a),
2.76−2.92 (m, 2H, H−5, 8b), 2.37 (dd, J = 14.8, 6.3 Hz, 1H, H−5), 1.93 (ad, J = 2.5 Hz, 3H, H−12),
1.04−1.11 (m, 2H, H−10), 1.02 (d, J = 7.3 Hz, 3H, H−11), 0.98 (d, J = 7.8 Hz, 3H, H−11), 0.97 (d, J =
7.3 Hz, 3H, H−11), 0.94 (d, J = 7.8 Hz, 3H, H−11); 13C NMR (300 MHz, C6D6) δ 177.9 (C−6), 176.0
(C−8), 144.8 (C−4), 133.0 (C−13), 132.5 (C−3), 128.8 (C−15), 128.1 (C−16), 126.4 (C−14), 67.7
(C−9), 42.7 (C−8b), 40.8 (C−5a/8a), 40.7 (C−5a/8a), 31.1 (C−5), 26.3 (C−12), 18.2 (C−11), 17.7
(C−11), 17.4 (C−11), 13.4 (C−10), 13.3 (C−10); HRMS calcd for C22H30NO3NaSi (M+Na)+ 406.1814,
found 406.1770. The unreacted diene (excess) was recovered after the volatiles were
rotovapped (0.093 g, 0.442 mmol, 37%).
(5αS,8αS,8βR)-5,5a-Dihydro-3,3,4-trimethyl-7-phenyl-1H-[1,2]oxasilolo[4,3-e]isoindole-6,8(3H,
7H,8αH,8βH)-dione [13.2.11b]. Compound 13.2.4e (0.449 g, 2.91 mmol), N-phenylmaleimide
(0.195 g, 1.13 mmol) were used according to the general procedure. After heating for 24 h, and
flash chromatography resulted eluting the excess unreacted diene (pentane/Et2O, 2:1) as first
Si
O
N
O
O1
2
3
4 5 6 7
8
910
11
12
13
14 15
16
H
H
H5a
8a
8b
H H
H
H
(13.2.10b)
127
elutant followed by increasing polarity of the mobile phase (100% Et2O) yields 13.2.11b as
clear colorless viscous liquid (0.323 g, 0.986 mmol, 88%): Rf 0.53 (100% Et2O); 1H NMR (500 MHz,
CDCl3) δ 7.44 (t, J = 7.7 Hz, 2H, H−14), 7.35 (t, J = 7.4 Hz, 1H,
H−15), 7.16 (ad, J = 8.3 Hz, 2H, H−13), 4.72 (dd, J = 10.1, 6.6 Hz,
1H, H−9), 4.35 (dd, J = 10.1, 8.5 Hz, 1H, H−9), 3.24−3.36 (m, 2H,
H−5a, 8a), 2.73−2.87 (m, 2H, H−5, 8b), 2.28 (dd, J = 14.8, 6.3 Hz,
1H, H−5), 1.89 (bs, 3H, H−11), 0.29 (s, 3H, H−10), 0.18 (s, 3H, H−10); 1H NMR (500 MHz, C6D6) δ
7.34 (ad, J = 7.8 Hz, 2H, H−13), 7.10 (at, J = 7.8 Hz, 2H, H−14), 6.96 (at, J = 7.6 Hz, 1H, H−15), 5.02
(dd, J = 10.3, 6.3 Hz, 1H, H−9), 4.28 (dd, J = 10.3, 8.6 Hz, 1H, H−9), 2.56 (dd, J = 14.6, 1.8 Hz, 1H,
H−5), 2.46 (ddd, J = 8.8, 6.8, 1.8 Hz, 1H, H−5a), 2.39 (dd, J = 8.8, 6.8 Hz, 1H, H−8a), 2.15−2.25 (m,
1H, H−8b), 1.65 (add, J = 14.6, 6.8, 1H, H−5), 1.60 (as, 3H, H−11), 0.20 (s, 3H, H−10), 0.14 (s, 3H,
H−10); 13C NMR (300 MHz, CDCl3) δ 178.5 (C−6), 176.8 (C−8), 144.6 (C−4), 134.7 (C−3), 131.9
(C−12), 129.1 (C−13), 128.5 (C−15), 126.3 (C−14), 66.5 (C−9), 41.9 (C−8b), 41.5 (C−8a), 40.8
(C−5a), 31.5 (C−5), 24.7 (C−11), -0.65 (C−10), -0.71 (C−10); 13C NMR (300 MHz, C6D6) δ 177.8
(C−6/8), 176.3 (C−6/8), 144.4 (C), 135.6 (C), 132.9 (C), 129.0 (C−14), 128.2 (C−15), 126.5 (C−13),
66.7 (C−9), 42.5 (C−8b), 41.5 (C−8a), 40.9 (C−5a), 31.6 (C−5), 24.5 (C−11), -0.52 (C−10); HRMS
calcd for C18H22NO3Si (M+H)+ 328.1369, found 328.1376. The unreacted (excess) diene (0.192 g,
1.244 mmol, 69.8%) was recovered after removal of volatiles by rotovap and was found as in
pure form: Rf 0.78 (pentane/Et2O, 1:2).
Synthesis of [(3a,4,7,7a-tetrahydro-3a-methyl-isobenzofuran-1,3-dione)-6-yl] silatranene
(13.1.3a) & [(3a,4,7,7a-tetrahydro-3a-methyl-isobenzofuran-1,3-dione)-5-yl] silatrane
(13.1.3b). Diene (13.1.2a) (0.271 g, 1.19 mmol) and citraconic anhydride (0.163 g, 1.45 mmol)
were heated at 120 ⁰C over a period of 48 h according to the general procedure. The reaction
mixture brought to room temperature, the product was precipitated with pentane (10 mL) and
128
following vacuum filtration the cycloadducts (9, 10) were isolated as a white crystalline solid
(0.314 g, 0.925 mmol, 78%): m.p (neat) 164 ⁰C (dec); Major Isomer (13.1.3a): 1H NMR (500 MHz,
C6D6): δ 6.63−6.82 (m, 1H, H−5), 3.32 (t,
J = 6.0 Hz, 6H, H−8), 3.20 (d, J = 14.0 Hz,
1H, H−7), 2.44 (dd, J = 15.0, 6.2 Hz, 1H,
H−4), 2.21−2.34 (m, 2H, H−7,7a), 1.83
(t, J = 6.0 Hz, 6H, H−9), 1.55 (ddd, J = 15.0, 3.7, 1.8 Hz, 1H, H−4), 0.78 (s, 3H, H−10); 13C NMR (300
MHz, C6D6) δ 178.2 (C−3), 173.7 (C−1), 143.81 (C−6), 133.5 (C−5), 57.5 (C−8), 50.6 (C−9), 47.45
(C−7a), 46.0 (C−3a), 33.1 (C−4), 28.0 (C−7), 23.9 (C−10); Minor Isomer (13.1.3b): Diagnostic
peaks: 1H NMR (500 MHz, C6D6): δ 3.30 (t, J = 6.0 Hz, 6H, H−8), 3.08 (d, J = 15.0 Hz, 1H, H−4),
2.53 (ddd, J = 15.7, 6.2, 2.7 Hz, 1H, H−7), 2.15 (dd, J = 6.7, 2.7 Hz, 1H, H−7a), 2.03 (dt, J = 15.0,
2.2 Hz, 1H, H−4), 1.81 (t, J = 6.0 Hz, 6H, H−9), 1.72−1.79 (m, 1H, H−7), 0.97 (s, 3H, H−10); 13C
NMR (300 MHz, C6D6) δ 177.6 (C−3), 174.2 (C−1), 143.77 (C−5), 133.0 (C−6), 47.50 (C−7a), 45.2
(C−3a), 36.9 (C−4), 24.2 (C−7), 23.6 (C−10); HRMS calcd for C15H21SiNO6 (M+) 339.1138, found
339.1138. Regio isomer ratio 2.0: 1.0 (based on 1H NMR)
Synthesis of potassium bis(8,8’-benzenediolato)-[(3a,4,7,7a-tetrahydro-3a-methyl-
isobenzofuran-1,3-dione)-6-yl]silicate (13.1.4a) & potassium bis(8,8’-benzenediolato)-
[(3a,4,7,7a-tetrahydro-3a-methyl-isobenzofuran-1,3-dione)-5-yl]silicate (13.1.4b). Diene –
13.1.2c (0.10 g, 0.298 mmol) and citraconic
anhydride (0.073 g, 0.651 mmol) were heated at 90
⁰C over a period of 36 h according to the general
procedure. The reaction mixture was brought to
room temperature, the product precipitated with pentane (15 mL) and following vacuum
filtration the cycloadducts were isolated (13.1.4a, 13.1.4b) as a brown amorphous solid (0.104 g,
1
23
4
5
67
8
9
10
11
3a
7a
SiO
O
OO
K
O
O
O
Me
H SiO
O
OO
3
4
K
O
O
O
7
8'
H
Me
8'
1 2
5
68
9
10
3a
7a
Major Isomer (13.1.4a) Minor Isomer (13.1.4b)
11
129
0.232 mmol, 78%): m.p (neat) 208 ⁰C (dec); Major Isomer (13.1.4a): 1H NMR (500 MHz,
DMSO): δ 6.53−6.65 (m, 4H, H−9/10), 6.43−6.52 (m,, 4H, H−9/10), 6.14 (t, J = 4.73 Hz, 1H, H−5),
3.06 (dd, J = 7.6, 4.4 Hz, 1H, H−7a), 2.16−2.35 (m, 3H, H−4, 7), 2.03 (d, J = 14.8 Hz, 1H, H−4), 1.15
(s, 3H, H−11); 13C NMR (500 MHz, DMSO) δ 177.4 (C−3), 174.3 (C−1), 150.5 (C−8/8’), 150.3
(C−8/8’), 141.5 (C−6), 134.2 (C−5), 117.32 (C−9/10), 117.28 (C−9/10), 109.6 (C−9/10), 109.58
(C−9/10), 45.2 (C−7a), 44.4 (C−3a), 35.2 (C−4), 23.1 (C−7), 22.3 (C−11); Minor Isomer (13.1.4b):
diagnostic peaks: 1H NMR (500 MHz, DMSO): δ 6.09−6.12 (m, 1H, H−6), 3.02 (dd, J = 7.6, 3.5 Hz,
1H, H−7a), 2.58 (p, J = 1.9 Hz, 1H, H−7), 1.88 (dd, J = 1.6 Hz, 1H, H−4), 1.26 (s, 3H, H−11); 13C
NMR (500 MHz, DMSO) δ 178.1 (C=O), 173.5 (C=O), 134.0 (C−6), 119.2 (C−9/10), 115.8 (C−9/10),
45.6 (C−7a), 32.8 (C−4), 26.0 (C−7), 22.8 (C−11); LRMS (FAB¯) m/z 409 (M¯ − K+, 48), 407 (15), 353
(19), 325 (17); Regio isomer ratio 4.8:1.0 (based on 1H NMR).
General procedure for cross-coupling reactions: These reactions were carried out by analogy to
the reported literature procedure.[138] Diels-Alder cycloadduct, Pd(OAc)2, PPh3 and aryliodide
were taken in 50 mL, single neck round bottom flask fitted with reflux condenser, and dissolved
in dis. DMF (10 mL). This transparent yellow colored reaction mixture was stirred to
homogenate followed by addition of TBAF dissolved in THF (0.5 mL), results the reaction mixture
to turn dark brown color, was purged with N2, and heated in an oil bath for 2h at 90 ⁰C. During
the course of reaction, the reaction mixture turned to dark black and the formation of active
palladium species (PdII → Pd0) was also noticed as the catalyst slowly turned to black solid. The
reaction mixture was then quenched with water (50 mL), and extracted with Et2O (4 × 50 mL).
The combined organic layers were again washed with water (2 × 75 mL), dried over MgSO4 and
volatiles were removed by rotary evaporation. The resulted cross-coupled cycloadduct residue
was purified by flash chromatography.
130 Synthesis of 3a,4,7,7a-tetrahydro-2,5-diphenyl-2H-isoindole-1,3-dione (13.3.2a).
Compound 13.1.1c (0.155 g, 0.387 mmol), Pd(OAc)2 (0.024 g, 0.041 mmol), PPh3 (0.024 g, 0.092
mmol), Iodobenzene (0.083 g, 0.407 mmol) and TBAF (0.118 g,
0.374 mmol) were used according to the general procedure
mentioned above. The resulted brown colored oily crude
reaction mixture was subjected to flash chromatography to
yield the cross-coupled product (13.3.2a) as a white solid (0.098 g, 0.323 mmol, 83%): m.p (neat)
122−124 ⁰C; Rf 0.27 (hexanes/diethyl ether, 1:1); 1H NMR (500 MHz, CDCl3) δ 7.38−7.45 (m, 2H,
H-10), 7.30−7.38 (m, 5H), 7.24−7.29 (m, 1H), 7.10−7.20 (m, 2H), 6.15−6.27 (m, 1H, H−6), 3.44
(ddd, J = 9.5, 6.9, 2.5 Hz, 1H, H−3a), 3.35 (ddd, J = 9.5, 6.9, 2.5 Hz,1H, H−7a), 3.26 (dd, J = 15.1,
2.5 Hz, 1H, H−4), 2.95 (ddd, J = 15.5, 6.9, 2.5 Hz, 1H, H−7), 2.64 (ddt, J = 15.1, 6.9, 2.5 Hz, 1H,
H−4), 2.40−2.50 (m, 1H, H−7); 13C NMR (500 MHz, CDCl3) δ 179.1 (C−1), 178.9 (C−3), 140.4
(C−12), 140.1 (C−5), 131.2 (C−8), 129.1 (C−10), 128.58 (C−13/14/15), 128.56 (C−13/14/15), 127.5
(C−11), 126.4 (C−9), 125.5 (C−13/14/15), 123.2 (C−6), 40.1 (C−3a), 39.5 (C−7a), 27.6 (C−4), 25.3
(C−7); HRMS calcd for C20H17O2N (M+) 303.1259, found 303.1251.
Synthesis of (3aR, 7aS)-5-(2-methoxyphenyl)-2-phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-
1,3(2H)-dione (13.3.2b). Cycloadduct 13.1.1c (0.101 g, 0.252 mmol), Pd(OAc)2 (0.020 g, 0.034
mmol), PPh3 (0.024 g, 0.092 mmol), 2-iodoanisole (0.084 g, 0.359 mmol) and TBAF (0.110 g,
0.349 mmol) were used according to the general procedure
mentioned above. The resulting brown colored oily crude
reaction mixture was subjected to flash chromatography to
yield the cross-coupled product 13.3.2b as a brownish-yellow crystalline solid (0.048 g, 0.144
mmol, 57%): m.p (neat) 128−132 ⁰C (dec.); Rf 0.42 (diethyl ether/hexanes, 2:1); 1H NMR (500
MHz, CDCl3) δ 7.44 (t, J = 8.1 Hz, 2H, H−10), 7.37 (t, J = 7.5 Hz, 1H, H−11), 7.18−7.25 (m, 3H, H−9,
1 2
34
5
6 78
9 10
113a
7aN
O
O
H
H
O
(13.3.2b)
12
1314
15
17
18
16
131
15), 7.08 (d, J = 7.5 Hz, 1H, H−17), 6.90 (t, J = 7.5 Hz, 1H, H−16), 6.83 (d, J = 8.1 Hz, 1H, H−14),
6.03 (p, J = 3.4 Hz, 1H, H−6), 3.67 (s, 3H, H−18), 3.36 (ddd, J = 9.1, 7.7, 2.4 Hz, 1H, H−3a), 3.32
(ddd, J = 9.1, 6.7, 2.6 Hz, 1H, H−7a), 3.07 (dd, J = 15.4, 2.4 Hz, 1H, H−4), 2.94 (ddd, J = 15.4, 6.7,
2.6 Hz, 1H, H−7), 2.63 (ddt, J = 15.4, 7.7, 2.4 Hz, 1H, H−4), 2.37−2.50 (m, 1H, H−7); 13C NMR (300
MHz, CDCl3) δ 179.2(C−1), 178.8 (C−3), 156.5 (C−13), 139.5 (C−5), 132.3 (C−8), 130.9 (C−12),
129.2 (C−11/17), 129.0 (C−10), 128.8 (C−11/17), 128.5 (C−15), 126.7 (C−9), 125.1 (C−6), 120.6
(C−16), 110.5 (C−14), 54.9 (C−18), 40.0 (C−3a/7a), 39.8 (C−3a/7a), 28.9 (C−4), 24.5 (C−7); HRMS
calcd for C21H19NO3Cs (M+) 466.0419, found 466.0430.
Synthesis of (3aR, 7aS)-5-(3-methoxyphenyl)-2-phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-
1,3(2H)-dione (13.3.2c). Cycloadduct 13.1.1c (0.100 g, 0.250 mmol), Pd(OAc)2 (0.028 g, 0.047
mmol), PPh3 (0.024 g, 0.088 mmol), 3-iodoanisole (0.126 g,
0.538 mmol) and TBAF (0.128 g, 0.406 mmol) were used
according to the general procedure mentioned above. The
resulting brown colored oily crude reaction mixture was
subjected to flash chromatography to yield the cross-coupled product 13.3.2c as a brown
colored oily substance (0.073 g, 0.219 mmol, 88%): Rf 0.15 (diethyl ether/hexanes, 2:1); 1H NMR
(500 MHz, CDCl3) δ 7.41 (at, J = 8.1 Hz, 2H, H−10), 7.35 (at, J = 8.1 Hz, 1H, H−11), 7.19–7.25 (m,
1H, H−16), 7.16 (ad, , J = 8.1 Hz, 2H, H−9), 6.91–7.02 (m, 1H, H−17), 6.90 (at, J = 2.1 Hz, 1H,
H−13), 6.81 (dd, J = 8.3, 2.5 Hz, 1H, H−15), 6.22 (p, J = 3.4 Hz, 1H, H−6), 3.80 (s, 3H, H−18), 3.44
(ddd, J = 9.4, 7.0, 2.5 Hz, 1H, H−3a), 3.34 (ddd, J = 9.4, 7.2, 2.5 Hz, 1H, H−7a), 3.24 (dd, J = 15.3,
2.5 Hz, 1H, H−4), 2.93 (ddd, J = 15.3, 7.0, 2.5 Hz, 1H, H−7), 2.64 (ddt, J = 15.3, 7.0, 2.3 Hz, 1H,
H−4), 2.37−2.51 (m, 1H, H−7); 13C NMR (300 MHz, CDCl3) δ 179.0(C−1), 178.8 (C−3), 159.8
(C−14), 141.9 (C−12), 140.0 (C−5), 132.0 (C−8), 129.5 (C−16), 129.1 (C−10), 128.6 (C−11), 126.4
132 (C−9), 123.4 (C−6), 118.0 (C−17), 113.1 (C−15), 111.2 (C−13), 55.5 (C−18), 40.1 (C−3a), 39.5
(C−7a), 27.7 (C−4), 25.3 (C−7); HRMS calcd for C21H19NO3Cs (M+) 466.0419, found 466.0444.
Synthesis of 3a,4,7,7a-tetrahydro-5-(4-methoxyphenyl)-2-phenyl-2H-isoindole-1,3-dione
(13.3.2d). Compound 13.1.1c (0.102 g, 0.255 mmol), Pd(OAc)2 (0.016 g, 0.027 mmol), PPh3
(0.015 g, 0.057 mmol), 4-iodoanisole (0.065 g, 0.278
mmol) and TBAF (0.098 g, 0.311 mmol) were used
according to the procedure mentioned as above. The
resulted brown colored impure solid was subjected to
flash chromatography to yield the cross-coupled product (13.3.2d) as a yellowish white solid
(0.058 g, 0.174 mmol, 68%): m.p (neat) 142−144 ⁰C; Rf 0.32 (diethyl ether/hexane, 1:1); 1H NMR
(500 MHz, CDCl3) δ 7.41 (t, J = 7.6 Hz, 2H, H−10), 7.34 (t, J = 7.6 Hz, 1H, H−11), 7.31 (d, J = 8.7 Hz,
2H, H−13), 7.15 (d, J = 7.6 Hz, 2H, H−9), 6.86 (d, J = 8.7 Hz, 2H, H−14), 6.12 (p, J = 3.2 Hz, 1H,
H−6), 3.80 (s, 3H, H−16), 3.42 (ddd, J = 9.3, 7.0, 2.6 Hz, 1H, H−3a), 3.33 (ddd, J = 9.3, 7.4, 2.4
Hz,1H, H−7a), 3.26 (dd, J = 15.1, 2.5 Hz, 1H, H−7), 2.95 (ddd, J = 15.5, 6.9, 2.5 Hz, 1H, H−4), 2.64
(ddt, J = 15.1, 6.9, 2.5 Hz, 1H, H−7), 2.40−2.50 (m, 1H, H−4); 13C NMR (500 MHz, CDCl3) δ 179.2
(C−1), 178.9 (C−3), 159.2 (C−15), 139.4 (C−5), 133.0 (C−12), 132.0 (C−8), 129.1 (C−10), 128.5
(C−11), 126.6 (C−13), 126.4 (C−9), 121.3 (C−6), 113.9 (C−14), 55.3 (C−16), 40.1 (C−3a), 39.6
(C−7a), 27.6 (C−4), 25.2 (C−7); HRMS calcd for C21H19O3N (M+) 333.1365, found 333.1370.
Synthesis of (3aR, 7aS)-5-(2-fluorophenyl)-2-phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-
1,3(2H)-dione (13.3.2e). Cycloadduct 13.1.1c (0.135 g, 0.337 mmol), Pd(OAc)2 (0.023 g, 0.039
mmol), PPh3 (0.024 g, 0.092 mmol), 1-iodo-2-fluorobenzene (0.126 g, 0.568 mmol) and TBAF
(0.132 g, 0.418 mmol) were used according to the general procedure mentioned above. The
resulting brown colored oily crude reaction mixture was subjected to flash chromatography to
yield the cross-coupled product 13.3.2e as a whitish-yellow, amorphous solid (0.091 g, 0.283
133 mmol, 84%): m.p (neat) 110−112 ⁰C; Rf 0.27 (diethyl ether/hexanes, 1:1); 1H NMR (500 MHz,
CDCl3) δ 7.44 (t, J = 7.6 Hz, 2H, H−10), 7.37 (tt, J = 7.6, 1.3 Hz, 1H, H−11), 7.15−7.25 (m, 4H, H−9,
17, 16/15), 7.09 (td, J = 7.6, 1.0 Hz, 1H, H−15/16), 7.04
(ddd, J = 10.7, 8.2, 1.0 Hz, 1H, H−14), 6.21 (p, J = 3.2
Hz, 1H, H−6), 3.41 (ddd, J = 9.5, 6.9, 2.5 Hz, 1H, H−3a),
3.35 (ddd, J = 9.5, 6.9, 2.5 Hz, 1H, H−7a), 3.16 (dd, J =
15.5, 1.6 Hz, 1H, H−4), 2.94 (ddd, J = 15.5, 6.9, 2.5 Hz, 1H, H−7), 2.73 (ddq, J = 15.5, 7.3, 1.3 Hz,
1H, H−4), 2.47 (dddd, J = 15.5, 6.6, 3.5, 2.5 Hz, 1H, H−7); 13C NMR (300 MHz, CDCl3) δ 178.9
(C−1), 178.7 (C−3), 159.7 (d, 1JC-F = 247.7 Hz, C−13), 135.3 (C−5), 132.0 (C−8), 129.1 (C−10),
128.99 (d, 3JC-F = 5.7 Hz, C−15/17), 128.91 (d, 3
JC-F = 5.7 Hz, C−15/17), 128.79 (C−12), 128.6
(C−11), 127.2 (d, 4JC-F = 3.4 Hz, C−6), 126.4 (C−9), 124.2 (d, 4
JC-F = 3.4 Hz, C−16), 115.9 (d, 2JC-F =
22.4 Hz, C−14), 40.0 (C−3a/7a), 39.3 (C−3a/7a), 28.6 (d, 4JC-F = 2.3 Hz, C−4), 25.0 (C−7); 19F NMR
(300 MHz, CDCl3) δ −116.3; HRMS calcd for C20H16FNO2Cs (M+) 454.0219, found 454.0238. Anal.
calcd for C20H16FNO2: C, 74.75; H, 5.02. Found: C, 74.47; H, 5.08.
Synthesis of (3aR, 7aS)-2-phenyl-5-(2-(trifluoromethyl)phenyl)-3a,4,7,7a-tetrahydro-1H-
isoindole-1,3(2H)-dione (13.3.2f). Cycloadduct 13.1.1c (0.158 g, 0.394 mmol), Pd(OAc)2 (0.022 g,
0.037 mmol), PPh3 (0.020 g, 0.076 mmol), 1-iodo-2-
(trifluoromethyl)benzene (0.122 g, 0.448 mmol) and
TBAF (0.126 g, 0.399 mmol) were used according to
the general procedure mentioned above. The resulting
brown colored oily crude reaction mixture was subjected to flash chromatography to yield the
cross-coupled product 13.3.2f as a yellow-brown liquid (0.11 g, 0.296 mmol, 75%): Rf 0.68
(diethyl ether/hexanes, 1:1); 1H NMR (500 MHz, CDCl3) δ 7.63 (d, J = 7.8 Hz, 1H, H−14),
7.43−7.54 (m, 3H, H−10, 16), 7.40 (tt, J = 7.6, 2.0 Hz, 1H, H−11), 7.36 (t, J = 7.8 Hz, 1H, H−15),
134 7.29 (dt, J = 7.6, 2.0 Hz, 1H, H−9), 7.10 (d, J = 7.8 Hz, 1H, H−17), 5.95 (p, J = 3.4 Hz, 1H, H−6),
3.40 (ddd, J = 9.4, 7.0, 2.6 Hz, 1H, H−3a), 3.39 (ddd, J = 9.4, 7.0, 2.6 Hz, 1H, H−7a), 2.81−2.98 (m,
2H, H−4, 7), 2.66−2.80 (m, 1H, H−4), 2.40−2.57 (m, 1H, H−7); 13C NMR (300 MHz, CDCl3) δ 179.0
(C−1), 178.8 (C−3), 141.2 (q, 3JC-F = 2.3 Hz, C−12), 138.4 (C−5), 132.0 (C−8), 131.8 (C−11/15/16),
129.9 (C−17), 129.1 (C−10), 128.6 (C−11/15/16), 127.8 (q, 2JC-F = 29.9 Hz, C−13), 127.3
(C−11/15/16), 126.5 (q, 5JC-F = 1.7 Hz, C−6), 126.3 (C−9), 126.1 (q, 3
JC-F = 5.2 Hz, C−14), 124.2 (q,
1JC-F = 273.6 Hz, C−18), 39.9 (C−3a), 38.8 (C−7a), 29.6 (q, 5
JC-F = 1.7 Hz, C−4), 24.7 (C−7); 19F NMR
(300 MHz, CDCl3) δ −58.2; HRMS calcd for C21H16F3NO2Cs (M+) 504.0187, found 504.0219.
Synthesis of (3aR, 7aS)-2-phenyl-5-(3-(trifluoromethyl)phenyl)-3a,4,7,7a-tetrahydro-1H-
isoindole-1,3(2H)-dione (13.3.2g). Cycloadduct 13.1.1c (0.100 g, 0.25 mmol), Pd(OAc)2 (0.018 g,
0.030 mmol), PPh3 (0.018 g, 0.069 mmol), 1-iodo-3-(trifluoromethyl)benzene (0.096 g, 0.353
mmol) and TBAF (0.092 g, 0.292 mmol) were used
according to the general procedure mentioned above.
The resulting brown colored oily crude reaction mixture
was subjected to flash chromatography to yield the
cross-coupled product 13.3.2g as a brown colored liquid
(0.084 g, 0.226 mmol, 90%): Rf 0.16 (diethyl ether/hexanes, 1:1); 1H NMR (500 MHz, CDCl3) δ
7.60 (s, 1H, H−13), 7.54 (d-overlapped, J = 7.9 Hz, 1H, H−17), 7.52 (d-overlapped, J = 8.1 Hz, 1H,
H−15), 7.39−7.48 (m, 3H, H−10, 16), 7.36 (att, J = 7.3, 1.4 Hz, 1H, H−11), 7.15 (d, J = 7.3 Hz, 2H,
H−9), 6.30 (p, J = 3.5 Hz, 1H, H−6), 3.47 (ddd, J = 9.4, 6.9, 2.7 Hz, 1H, H−3a), 3.37 (ddd, J = 9.4,
7.5, 2.5 Hz, 1H, H−7a), 3.25 (dd, J = 15.4, 2.7 Hz, 1H, H−4), 2.97 (ddd, J = 15.6, 6.9, 2.5 Hz, 1H,
H−7), 2.67 (ddt, J = 15.4, 6.9, 2.5 Hz, 1H, H−4), 2.47 (dddd, J = 15.6, 6.2, 3.7, 2.5 Hz, 1H, H−7); 13C
NMR (300 MHz, CDCl3) δ 178.8 (C−1), 178.6 (C−3), 141.1 (C−12), 138.9 (C−5), 131.8 (C−8), 131.0
(q, 2JC-F = 32.2 Hz, C−14), 129.13 (C−10), 129.11 (C−17), 128.7 (q, 4
JC-F = 1.7 Hz, C−16), 128.6
135 (C−11), 126.3 (C−9), 125.0 (C−6), 124.2 (q, 3
JC-F = 4.0 Hz, C−13), 124.0 (q, 1JC-F = 273.0 Hz,
C−18), 122.4 (q, 3JC-F = 4.0 Hz, C−15), 40.0 (C−3a), 39.2 (C−7a), 27.5 (C−4), 25.3 (C−7); 19F NMR
(300 MHz, CDCl3) δ −63.2; HRMS calcd for C21H16F3NO2 (M+) 371.1133, found xxx.xxxx. Anal. calcd
for C21H16F3NO2: C, 67.92; H, 4.34. Found: C, xx.xx; H, x.xx.
Synthesis of (3aR, 7aS)-2-phenyl-5-(4-(trifluoromethyl)phenyl)-3a,4,7,7a-tetrahydro-1H-
isoindole-1,3(2H)-dione (13.3.2h). Cycloadduct 13.1.1c (0.099 g, 0.247 mmol), Pd(OAc)2 (0.023
g, 0.039 mmol), PPh3 (0.024 g, 0.092 mmol), 1-
iodo-4-(trifluoromethyl)benzene (0.132 g, 0.485
mmol) and TBAF (0.098 g, 0.311 mmol) were used
according to the general procedure mentioned
above. The resulting brown colored oily crude reaction mixture was subjected to flash
chromatography to yield the cross-coupled product 13.3.2h as a yellow-brown liquid (0.082 g,
0.221 mmol, 89%): Rf 0.35 (diethyl ether/hexanes, 2:1); 1H NMR (500 MHz, CDCl3) δ 7.58 (d, J =
8.4 Hz, 2H, H−13), 7.46 (d, J = 8.4 Hz, 2H, H−14), 7.42 (t, J = 7.5 Hz, 2H, H−10), 7.36 (t, J = 7.5 Hz,
1H, H−11), 7.14 (t, J = 7.5 Hz, 2H, H−9), 6.31 (p, J = 3.4 Hz, 1H, H−6), 3.47 (ddd, J = 9.4, 6.7, 2.5
Hz, 1H, H−3a), 3.38 (ddd, J = 9.4, 7.1, 2.3 Hz, 1H, H−7a), 3.27 (dd, J = 15.3, 2.5 Hz, 1H, H−4), 2.99
(ddd, J = 15.6, 7.1, 2.3 Hz, 1H, H−7), 2.65 (ddt, J = 15.3, 6.7, 2.5 Hz, 1H, H−4), 2.37−2.54 (m, 1H,
H−7); 13C NMR (300 MHz, CDCl3) δ 178.8 (C−1/3), 178.7 (C−1/3), 143.7 (q, 5JC-F = 1.1 Hz, C−12),
139.1 (C−5), 131.8 (C−8), 129.5 (q, 2JC-F = 32.8 Hz, C−15), 129.1 (C−10), 128.6 (C−11), 126.3 (C−9),
125.8 (C−13), 125.5 (q, 3JC-F = 4.0 Hz, C−14), 125.4 (C−6), 124.1 (q, 1
JC-F = 271.8 Hz, C−16), 40.0
(C−3a), 39.2 (C−7a), 27.4 (C−4), 25.3 (C−7); 19F NMR (300 MHz, CDCl3) δ −63.0; HRMS calcd for
C21H16F3NO2Cs (M+) 504.0187, found 504.0222.
Synthesis of (3aR, 7aS)-2-phenyl-5-(thiophen-2-yl)-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-
dione (13.3.2i). Cycloadduct 13.1.1c (0.15 g, 0.375 mmol), Pd(OAc)2 (0.022 g, 0.037 mmol), PPh3
136 (0.026 g, 0.099 mmol), 2-iodothiophene (0.126 g, 0.60 mmol) and TBAF (0.129 g, 0.409
mmol) were used according to the general procedure mentioned above. The oily crude reaction
mixture was purified by flash chromatography to yield
the cross-coupled product 13.3.2i as a brown colored
oily substance (0.059 g, 0.191 mmol, 51%): Rf 0.22
(diethyl ether/hexanes, 1:1); 1H NMR (300 MHz, CDCl3) δ
7.30–7.47 (m, 3H, H−10, 11), 7.10–7.22 (m, 3H, H−9, 15), 7.05 (ad, J = 3.4 Hz, 1H, H−13), 6.97 (at,
J = 4.3 Hz, 1H, H−14), 6.28 (p, J = 3.4 Hz, 1H, H−6), 3.40 (ddd, J = 9.6, 7.0, 2.8 Hz, 1H, H−3a), 3.31
(ddd, J = 9.6, 7.0, 2.6 Hz, 1H, H−7a), 3.22 (dd, J = 15.3, 2.8 Hz, 1H, H−4), 2.87 (ddd, J = 15.8, 7.0,
2.6 Hz, 1H, H−7), 2.67 (ddt, J = 15.3, 7.0, 2.3 Hz, 1H, H−4), 2.38−2.55 (m, 1H, H−7); 13C NMR (300
MHz, CDCl3) δ 178.8 (C−1), 178.4 (C−3), 143.9 (C−12), 133.3 (C−5), 131.9 (C−8), 129.0 (C−10),
128.5 (C−11), 127.5 (C−14), 126.4 (C−9), 124.2 (C−15), 123.0 (C−13), 121.4 (C−6), 39.7 (C−3a/7a),
39.3 (C−3a/7a), 27.5 (C−4), 24.8 (C−7); HRMS calcd for C18H15NO2SCs (M+) 441.9878, found
441.9891.
Synthesis of 3-[(3aR,7aS)-1,3-dioxo-2-phenyl-2,3,3a,4,7,7a-hexahydro-1H-isoindol-5-
yl]benzonitrile (13.3.2j). Cycloadduct 13.1.1c (0.150 g, 0.375 mmol), Pd(OAc)2 (0.027 g, 0.046
mmol), PPh3 (0.024 g, 0.088 mmol), 3-iodobenzonitrile
(0.118 g, 0.515 mmol) and TBAF (0.143 g, 0.453 mmol)
were used according to the general procedure
mentioned above. The resulting brown colored oily
crude reaction mixture was subjected to flash
chromatography to yield the cross-coupled product 13.3.2j as yellow-white solid (0.066 g, 0.201
mmol, 54%): m.p (neat) 157−159 ⁰C; Rf 0.51 (100% diethyl ether); 1H NMR (500 MHz, CDCl3) δ
7.63 (t, J = 1.5 Hz, 1H, H−13), 7.58 (dt, J = 7.9, 1.5 Hz, 1H, H−17), 7.54 (dt, J = 7.9, 1.5 Hz, 1H,
137 H−15), 7.39–7.48 (m, 3H, H−10, 16), 7.63 (tt, J = 7.4, 1.3 Hz, 1H, H−11), 7.15 (ad, J = 7.4 Hz,
2H, H−9), 6.29 (p, J = 3.4 Hz, 1H, H−6), 3.48 (ddd, J = 9.4, 6.8, 2.5 Hz, 1H, H−3a), 3.38 (ddd, J =
9.4, 7.6, 2.5 Hz, 1H, H−7a), 3.22 (dd, J = 15.3, 2.5 Hz, 1H, H−4), 2.98 (ddd, J = 15.7, 7.0, 2.5 Hz,
1H, H−7), 2.64 (ddt, J = 15.3, 6.8, 2.5 Hz, 1H, H−4), 2.47 (dddd, J = 15.7, 7.6, 3,6, 2.5 Hz, 1H, H−7);
13C NMR (300 MHz, CDCl3) δ 178.7 (C−1), 178.5 (C−3), 141.4 (C−12), 138.3 (C−5), 131.8 (C−8),
131.0 (C−15), 129.8 (C−17), 129.5 (C−13), 129.2 (C−10, 11), 128.7 (C−16), 126.3 (C−9), 125.7
(C−6), 118.7 (C−18), 112.9 (C−14), 40.0 (C−3a), 39.1 (C−7a), 27.2 (C−4), 25.4 (C−7); HRMS calcd
for C21H16N2O2Cs (M+) 461.0266, found 461.0280.
Synthesis of 3a,4,7,7a-tetrahydro-5-(4-methoxyphenyl)-2-phenyl-2H-isoindole-1,3-dione
(13.3.2k). Compound 13.1.1d (0.102 g, 0.255 mmol), Pd(OAc)2 (0.016 g, 0.027 mmol), PPh3
(0.015 g, 0.057 mmol), 4-iodoanisole (0.065 g, 0.278
mmol) and TBAF (0.098 g, 0.311 mmol) were used
according to the procedure mentioned as above. The
resulted brown colored impure solid was subjected to
flash chromatography to yield the cross-coupled product (13.3.2k) as a yellowish white solid
(0.058 g, 0.174 mmol, 68%): m.p (neat) 142−144 ⁰C; Rf 0.32 (diethyl ether/hexane, 1:1); 1H NMR
(500 MHz, CDCl3) δ 7.41 (t, J = 7.6 Hz, 2H, H−10), 7.34 (t, J = 7.6 Hz, 1H, H−11), 7.31 (d, J = 8.7 Hz,
2H, H−13), 7.15 (d, J = 7.6 Hz, 2H, H−9), 6.86 (d, J = 8.7 Hz, 2H, H−14), 6.12 (p, J = 3.2 Hz, 1H,
H−6), 3.80 (s, 3H, H−16), 3.42 (ddd, J = 9.3, 7.0, 2.6 Hz, 1H, H−3a), 3.33 (ddd, J = 9.3, 7.4, 2.4
Hz,1H, H−7a), 3.26 (dd, J = 15.1, 2.5 Hz, 1H, H−7), 2.95 (ddd, J = 15.5, 6.9, 2.5 Hz, 1H, H−4), 2.64
(ddt, J = 15.1, 6.9, 2.5 Hz, 1H, H−7), 2.40−2.50 (m, 1H, H−4); 13C NMR (500 MHz, CDCl3) δ 179.2
(C−1), 178.9 (C−3), 159.2 (C−15), 139.4 (C−5), 133.0 (C−12), 132.0 (C−8), 129.1 (C−10), 128.5
(C−11), 126.6 (C−13), 126.4 (C−9), 121.3 (C−6), 113.9 (C−14), 55.3 (C−16), 40.1 (C−3a), 39.6
(C−7a), 27.6 (C−4), 25.2 (C−7); HRMS calcd for C21H19O3N (M+) 333.1365, found 333.1370.
138 Synthesis of 1-(buta-1,3-dien-2-yl)benzene (13.3.4) under Domino Reaction Conditions.
Diene – 13.1.2a (0.108 g, 0.502 mmol), N-phenylmaleimide (0.107 g, 0.618 mmol), 0.5M TBAF
solution (0.93 mL, 0.465 mmol), PdCl2(PPh3)2 (0.005 g, 1.5 mol %), CuI
(0.015 g, 0.079 mmol) and Iodobenzene (0.102 g, 0.502 mmol) were taken
into a thick walled microwave tube equipped with stir-bar. The contents
were added with THF (2.0 mL) and the sealed tube was left at room
temperature for 36h with constant stirring. After which the reaction mixture was added to Et2O
(10 mL) and quenched with 1.2M HCl (10 mL) and filtered through a pad of silica to remove solid
particulate matter. The silica pad was washed with Et2O (2 × 10 mL), the resulting filtrate was
washed successively with 1.2M HCl (2 × 25 mL), water (2 × 25 mL) and dried over MgSO4. After
removal of volatiles, crude product was purified by flash chromatography resulted compound
13.3.4 as yellowish-brown oil (0.047 g, 0.361 mmol, 72%). Spectral data is consistent with earlier
reported literature.[179]
Synthesis of 3a,4,7,7a-tetrahydro-2-phenyl-2H-isoindole-1,3-dione (13.3.5) under Domino
Syntheses Protocol. Diene – 13.1.2a (0.150 g, 0.697 mmol), N-phenylmaleimide (0.233 g, 1.35
mmol), TBAF (0.240 g, 0.761 mmol), PdCl2(PPh3)2 (0.008 g, 1.5 mol%) and CuI (0.375 g, 1.97
mmol) were taken into a thick walled microwave tube equipped
with stir-bar. The tube was sealed after THF (2.0 mL) addition
resulted pink-violet cloudy reaction mixture was stirred for 9 h at
room temperature. After which the reaction mixture was added
to Et2O (10 mL) and quenched with 1.2M HCl (10 mL) and filtered through a pad of silica to
remove solid particulate matter. The silica pad was washed with Et2O (2 × 10 mL), the resulting
filtrate was washed successively with 1.2M HCl (2 × 25 mL), water (2 × 25 mL) and dried over
MgSO4. After the removal of volatiles by rotary evaporator, crude product was subjected to flash
139 chromatography resulted compound 13.3.5 as brown oil (0.040 g, 0.176 mmol, 25%).
Spectral data was consistent with those reported in literature.[180, 181, 217-219]
140
CHAPTER 4
17) Conclusion. We have prepared cobaloxime dienes with slight modifications to the
existing procedures and shown that they involve higher-order and Diels-Alder reactions. The
prepared cobaloxime dienes involve cycloaddition reactions with various tropones to give the
cycloadducts in moderate to high yields. From the X-ray and 1D and 2D NMR studies of the
formed cycloadducts, it was concluded that these cycloadditions were happening through ‘exo’
transition states. Tropones that are unsubstituted at bond-forming centers undergo [6+4]
cycloadditions with high stereo and regioselectivity to yield the [6+4] cycloadducts as single
isomer. Where as the tropones having substituents at the bond-forming centers (phenyl or
methyl) did undergo higher-order cycloaddition reactions to give the [6+4] adducts in moderate
yields. When the tropones having an EWG at the bond forming center were used, the reaction
happened through [4+2] cycloaddtion reaction to yield [4+2] cycloadduct as a single isomer.
When the tropone that are unsubstituted at bond forming centers and have atleast one EWG,
yielded two seperable cycloadducts forming through [6+4] and [4+2] cycloadditions. From these
reactions, it was evidenced that the transition metal (cobalt) has total control on stereo and
regioselectivity of the reaction and the substitutents on 6π system (EWG) dictates the reaction
pathway (higher-order vs Diels-Alder). Also, cobaloxime dienes with DMAP ligands were shown
much reactive than the coblaoxime dienes having pyridine ligand.
As a part of our on going search for developing catalytic reactions involving transition metals,
we have prepared various silyl dienes (11.3.2b, 13.1.2a-c, 13.2.4a-e ) in multi gram scale using
inexpensive, readily available commercial reagents in economic way. These dienes were
prepared in 2 to 4 steps in high yields both in oil, solid and crystalline forms. A comparative
study among the prepared silyl dienes and with other commercially available dienes were
141 indicated that the silatrane (13.1.2a) and catechol (13.1.2c) substituted silyl dienes were
more selective and reactive. When the reactivity of the silatrane diene (13.1.2a) was compared
with Danishefsky’s diene (13.1.2d) by NMR kinetics, they were found almost twice reactive as
Danishefsky’s diene. The cycloadducts prepared from the silyl dienes were shown to
participating in cross-coupling reactions to yield the cross-coupled adducts in moderate to high
yields.
Due to time constraints, we were only able to study a very few domino reactions in order to
develop new reaction sequences that involve successive transmetallation, Diels-Alder and cross-
coupling reactions to yield the cross-coupled cycloadducts. But in the reactions we carried out,
we were only able to isolate the cross-coupled diene when Pd (II), silyl diene (11.3.2b), N-
phenylmaleimide, iodobenzene and TBAF were taken together. From this we assumed that
transmetallation/oxidative addition/reductive elimination could not be intercepted by the Diels-
Alder reactions under these reactions conditions. Also, in another case we isolated a Diels-Alder
product formed from a less ambitious transmetallation/Diels-Alder/protonolysis reaction
sequence. From these preliminary results from our studies, it concludes that the silyl dienes and
the products evolved trough their reactions serve as synthons for cross-coupling reactions and it
is possible to develop new methodology (one-pot, domino reaction sequence) involving
successive transmetallation/Diels-Alder/oxidative addition/reductive elimination reactions to
yield cross-coupled cycloadduct.
142
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154
Appendix A
Crystallographic Data for [6+4] Cycloadduct, 5.2.2b
155
Table 1. Crystal data and structure refinement for Co(C4H7N2O2)2(C5H5N)(C12H13O) (5.2.2b)
Empirical formula C25 H32 Co N5 O5
Formula weight 541.49
Temperature 193(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic
Space group P2(1)/n
Unit cell dimensions a = 8.173(3) Å
b = 22.819(8) Å, β = 99.147(5)°
c = 13.929(5) Å
Volume 2564.9(15) Å3
Z 4
Density (calculated) 1.402 g/cm3
Absorption coefficient 0.714 mm-1
F(000) 1136
Crystal size 0.46 x 0.26 x 0.10 mm3
Theta range for data collection 3.99 to 24.15°
Index ranges -9≤h≤9, -26≤k≤26, -16≤l≤16
Reflections collected 16838
Independent reflections 4067 [R(int) = 0.1118]
Completeness to theta = 24.15° 99.1 %
Refinement method Full-matrix least-squares on F2
Data / restraints / parameters 4067 / 32 / 335
Goodness-of-fit on F2 0.901
Final R indices [I>2sigma(I)] R1 = 0.0682, wR2 = 0.1463
R indices (all data) R1 = 0.1236, wR2 = 0.1586
Largest diff. peak and hole 0.831 and -0.448 e-/Å3
156
Table 2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for
Compound(5B). U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
Co(1) -725(1) -528(1) -2565(1) 30(1)
O(1) -97(5) -660(2) -4496(3) 47(1)
O(2) 1358(5) -854(2) -813(3) 54(1)
O(3) -1365(5) -408(2) -639(3) 48(1)
O(4) -2796(5) -189(2) -4327(3) 45(1)
O(5) 1290(7) -2381(2) -2862(6) 114(3)
N(1) 487(6) -744(2) -3555(3) 32(1)
N(2) 1163(6) -835(2) -1790(4) 37(1)
N(3) -1931(6) -320(2) -1578(3) 33(1)
N(4) -2592(5) -221(2) -3342(3) 32(1)
N(5) 316(5) 291(2) -2485(3) 34(1)
C(1) 1912(7) -985(3) -3282(5) 41(2)
C(2) 2319(7) -1040(3) -2235(5) 45(2)
C(3) -3348(7) -54(2) -1854(4) 35(1)
C(4) -3743(7) 4(3) -2897(4) 33(1)
C(5) 3007(8) -1180(3) -3989(5) 63(2)
C(6) 3852(8) -1328(3) -1725(5) 63(2)
C(7) -4401(7) 174(3) -1153(4) 53(2)
C(8) -5277(7) 301(3) -3416(4) 47(2)
C(9) 324(7) 617(3) -3279(4) 42(2)
C(10) 960(8) 1179(3) -3235(6) 52(2)
C(11) 1634(8) 1411(3) -2364(6) 61(2)
C(12) 1653(8) 1075(3) -1536(5) 54(2)
C(13) 1009(7) 515(3) -1626(5) 42(2)
C(14) -1747(7) -1315(2) -2638(4) 34(1)
C(15) -1807(8) -1637(3) -1831(6) 56(2)
C(16) -2417(11) -2242(4) -1835(8) 98(3)
C(17) -1122(13) -2671(4) -2202(11) 147(5)
C(18) -198(11) -2373(3) -2922(8) 82(3)
C(19) -1174(11) -2082(4) -3851(8) 103(4)
C(20) -2346(8) -1582(3) -3588(5) 54(2)
157
C(21) -1914(19) -3256(5) -2570(19) 210(11)
C(22) -2453(13) -3368(8) -3556(19) 320(20)
C(23) -2551(13) -3071(8) -4200(19) 294(17)
C(24) -2041(15) -2492(5) -4519(11) 162(6)
C(25) -2793(14) -2442(5) -797(9) 146(5)
______________________________________________________________________________
158
Table 3. Bond lengths [Å] and angles [°] for Compound(5B)
_____________________________________________________
Co(1)-N(4) 1.862(4)
Co(1)-N(2) 1.872(5)
Co(1)-N(3) 1.875(4)
Co(1)-N(1) 1.886(4)
Co(1)-C(14) 1.976(6)
Co(1)-N(5) 2.050(5)
O(1)-N(1) 1.336(5)
O(2)-N(2) 1.345(6)
O(3)-N(3) 1.332(5)
O(4)-N(4) 1.357(6)
O(5)-C(18) 1.206(9)
N(1)-C(1) 1.290(7)
N(2)-C(2) 1.298(7)
N(3)-C(3) 1.311(7)
N(4)-C(4) 1.311(6)
N(5)-C(9) 1.333(7)
N(5)-C(13) 1.341(7)
C(1)-C(2) 1.449(9)
C(1)-C(5) 1.500(8)
C(2)-C(6) 1.490(8)
C(3)-C(4) 1.443(8)
C(3)-C(7) 1.494(7)
C(4)-C(8) 1.505(7)
C(9)-C(10) 1.382(8)
C(10)-C(11) 1.358(9)
C(11)-C(12) 1.383(9)
C(12)-C(13) 1.380(8)
C(14)-C(15) 1.350(8)
C(14)-C(20) 1.469(8)
C(15)-C(16) 1.467(10)
159
C(16)-C(17) 1.584(12)
C(16)-C(25) 1.592(13)
C(17)-C(18) 1.509(14)
C(17)-C(21) 1.535(18)
C(18)-C(19) 1.557(13)
C(19)-C(24) 1.426(13)
C(19)-C(20) 1.569(10)
C(21)-C(22) 1.40(3)
C(22)-C(23) 1.1161
C(23)-C(24) 1.47(2)
N(4)-Co(1)-N(2) 179.6(2)
N(4)-Co(1)-N(3) 81.6(2)
N(2)-Co(1)-N(3) 98.8(2)
N(4)-Co(1)-N(1) 98.6(2)
N(2)-Co(1)-N(1) 81.0(2)
N(3)-Co(1)-N(1) 179.5(2)
N(4)-Co(1)-C(14) 90.7(2)
N(2)-Co(1)-C(14) 89.6(2)
N(3)-Co(1)-C(14) 90.0(2)
N(1)-Co(1)-C(14) 89.6(2)
N(4)-Co(1)-N(5) 89.00(19)
N(2)-Co(1)-N(5) 90.73(19)
N(3)-Co(1)-N(5) 89.52(18)
N(1)-Co(1)-N(5) 90.90(18)
C(14)-Co(1)-N(5) 179.5(2)
C(1)-N(1)-O(1) 121.0(5)
C(1)-N(1)-Co(1) 116.8(4)
O(1)-N(1)-Co(1) 122.2(4)
C(2)-N(2)-O(2) 119.5(5)
C(2)-N(2)-Co(1) 117.1(4)
O(2)-N(2)-Co(1) 123.4(4)
C(3)-N(3)-O(3) 120.7(5)
C(3)-N(3)-Co(1) 116.4(4)
O(3)-N(3)-Co(1) 122.8(4)
C(4)-N(4)-O(4) 118.4(4)
160
C(4)-N(4)-Co(1) 117.1(4)
O(4)-N(4)-Co(1) 124.4(3)
C(9)-N(5)-C(13) 118.1(5)
C(9)-N(5)-Co(1) 121.3(4)
C(13)-N(5)-Co(1) 120.6(4)
N(1)-C(1)-C(2) 112.7(5)
N(1)-C(1)-C(5) 122.5(6)
C(2)-C(1)-C(5) 124.8(6)
N(2)-C(2)-C(1) 112.4(5)
N(2)-C(2)-C(6) 123.6(6)
C(1)-C(2)-C(6) 123.9(6)
N(3)-C(3)-C(4) 112.6(5)
N(3)-C(3)-C(7) 122.9(5)
C(4)-C(3)-C(7) 124.5(5)
N(4)-C(4)-C(3) 112.2(5)
N(4)-C(4)-C(8) 123.7(5)
C(3)-C(4)-C(8) 124.1(5)
N(5)-C(9)-C(10) 122.1(6)
C(11)-C(10)-C(9) 120.0(7)
C(10)-C(11)-C(12) 118.5(7)
C(13)-C(12)-C(11) 119.0(6)
N(5)-C(13)-C(12) 122.3(6)
C(15)-C(14)-C(20) 118.2(6)
C(15)-C(14)-Co(1) 121.6(5)
C(20)-C(14)-Co(1) 120.1(4)
C(14)-C(15)-C(16) 124.6(7)
C(15)-C(16)-C(17) 109.7(7)
C(15)-C(16)-C(25) 112.4(8)
C(17)-C(16)-C(25) 110.6(8)
C(18)-C(17)-C(21) 113.4(12)
C(18)-C(17)-C(16) 111.6(7)
C(21)-C(17)-C(16) 112.1(9)
O(5)-C(18)-C(17) 123.6(10)
O(5)-C(18)-C(19) 116.2(9)
C(17)-C(18)-C(19) 120.0(8)
C(24)-C(19)-C(18) 113.4(10)
161
C(24)-C(19)-C(20) 111.8(8)
C(18)-C(19)-C(20) 111.5(7)
C(14)-C(20)-C(19) 112.6(6)
C(22)-C(21)-C(17) 122.5(17)
C(23)-C(22)-C(21) 130.5(12)
C(22)-C(23)-C(24) 142.9(10)
C(19)-C(24)-C(23) 121.8(14)
_____________________________________________________________
162
Table 4. Anisotropic displacement parameters (Å2x 103) for Compound(5B). The anisotropic
displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]
______________________________________________________________________________
U11 U22 U33 U23 U13 U12
______________________________________________________________________________
Co(1) 23(1) 39(1) 29(1) 0(1) 7(1) 1(1)
O(1) 51(3) 65(3) 29(3) -6(2) 17(2) 6(2)
O(2) 44(3) 78(4) 37(3) 9(2) -1(2) 14(2)
O(3) 43(3) 76(3) 25(2) 8(2) 9(2) 3(2)
O(4) 37(3) 72(4) 27(3) 0(2) 3(2) 9(2)
O(5) 40(4) 56(4) 250(8) 0(4) 37(4) 9(3)
N(1) 29(3) 38(3) 34(3) -4(2) 16(2) 2(2)
N(2) 25(3) 50(3) 34(3) 5(2) 1(2) -1(2)
N(3) 29(3) 46(3) 25(3) 0(2) 10(2) -5(2)
N(4) 30(3) 42(3) 21(3) 1(2) -1(2) 3(2)
N(5) 28(3) 48(3) 27(3) 0(2) 11(2) 6(2)
C(1) 28(4) 40(4) 57(5) -8(3) 19(3) -2(3)
C(2) 29(4) 32(4) 73(5) 0(3) 8(3) 5(3)
C(3) 24(3) 44(4) 39(4) -6(3) 15(3) -2(3)
C(4) 22(3) 43(4) 34(4) -9(3) 4(3) 1(3)
C(5) 44(4) 65(5) 89(6) -14(4) 38(4) 7(4)
C(6) 34(4) 63(5) 90(6) 8(4) 2(4) 14(4)
C(7) 40(4) 80(5) 47(4) -8(4) 30(3) 6(4)
C(8) 30(4) 60(4) 48(4) -2(3) 0(3) 12(3)
C(9) 39(4) 48(4) 41(4) 5(3) 17(3) 6(3)
C(10) 40(4) 47(5) 77(6) 12(4) 30(4) 0(3)
C(11) 52(5) 46(5) 89(6) -17(5) 22(4) -14(4)
C(12) 43(4) 58(5) 60(5) -16(4) 7(4) -9(4)
C(13) 33(3) 49(4) 45(4) -9(3) 10(3) -3(3)
C(14) 27(3) 30(3) 47(4) 1(3) 12(3) 6(3)
C(15) 37(4) 53(5) 80(5) 10(4) 15(4) -6(3)
C(16) 79(7) 78(7) 144(9) 33(6) 36(6) 20(5)
C(17) 70(7) 65(7) 313(17) 33(9) 51(9) 23(6)
C(18) 44(5) 36(5) 173(10) 3(5) 36(6) 1(4)
C(19) 63(6) 96(8) 163(10) -45(7) 56(7) -14(6)
C(20) 32(4) 48(4) 85(5) -14(4) 16(4) -2(3)
163
C(21) 87(10) 40(7) 530(40) 35(13) 132(16) 11(7)
C(22) 150(20) 161(19) 710(70) -160(30) 200(30) -2(14)
C(23) 89(12) 190(20) 610(40) -280(20) 73(17) -28(11)
C(24) 146(11) 103(9) 255(15) -126(10) 89(11) -59(8)
C(25) 129(10) 106(9) 209(13) 92(8) 45(9) 6(7)
______________________________________________________________________________
164
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3)
for Compound(5B).
______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
H(2O) 690(90) -690(30) -630(50) 64
H(4O) -2260(90) -400(30) -4370(50) 55
H(5A) 2506 -1066 -4649 95
H(5B) 3135 -1607 -3956 95
H(5C) 4096 -994 -3824 95
H(6A) 3974 -1245 -1027 95
H(6B) 4816 -1175 -1983 95
H(6C) 3773 -1752 -1831 95
H(7A) -3748 187 -499 80
H(7B) -5357 -86 -1152 80
H(7C) -4788 569 -1347 80
H(8A) -6255 137 -3187 70
H(8B) -5363 236 -4118 70
H(8C) -5211 722 -3281 70
H(9) -122 457 -3896 50
H(10) 925 1403 -3813 63
H(11) 2083 1796 -2324 73
H(12) 2103 1227 -915 65
H(13) 1059 280 -1059 50
H(15) -1428 -1460 -1219 67
H(16) -3475 -2265 -2305 118
H(17) -279 -2766 -1621 176
H(19) -332 -1890 -4195 124
H(20A) -2438 -1276 -4096 65
H(20B) -3466 -1746 -3583 65
H(21) -2042 -3553 -2110 252
H(22) -2790 -3760 -3702 390
H(23) -3199 -3260 -4738 353
H(24) -2297 -2390 -5187 194
H(25A) -3384 -2128 -515 219
165
H(25B) -1748 -2524 -368 219
H(25C) -3479 -2796 -869 219
______________________________________________________________________________
Table 7. Hydrogen bonds for Compound(5B) [Å and °].
____________________________________________________________________________
D-H...A d(D-H) d(H...A) d(D...A) <(DHA)
____________________________________________________________________________
O(2)-H(2O)...O(3) 0.74(7) 1.79(7) 2.494(6) 157(8)
O(4)-H(4O)...O(1) 0.66(6) 1.90(7) 2.498(5) 151(9)
____________________________________________________________________________
166
Appendix B
Crystallographic Data for [4+2] Cycloadduct, 5.2.3b
167
Table 1. Crystal data and structure refinement for Co(C4H7N2O2)2(C7H10N2)(C19H23O6) (5.2.3b)
Empirical formula C34 H47 Co N6 O10
Formula weight 758.71
Temperature 193(2) K
Wavelength 0.71073 Å
Crystal system Orthorhombic
Space group Pna2(1) – C 92v
(No.33)
Unit cell dimensions a = 9.199(1) Å
b = 29.552(4) Å
c = 14.318(2) Å
Volume 3892.5(9) Å3
Z 4
Density (calculated) 1.295 g/cm3
Absorption coefficient 0.501 mm-1
F(000) 1600
Crystal size 0.22 x 0.19 x 0.04 mm3
Theta range for data collection 3.81 to 24.15°
Index ranges -10≤h≤10, -34≤k≤33, -16≤l≤16
Reflections collected 24196
Independent reflections 6189 [R(int) = 0.0820]
Completeness to theta = 24.15° 99.2 %
Absorption correction Multi-scan (SADABS)
Refinement method Full-matrix least-squares on F2
Data / restraints / parameters 6189 / 1 / 461
Goodness-of-fit on F2 1.204
Final R indices [I>2σ(I)] R1 = 0.0794, wR2 = 0.1736
R indices (all data) R1 = 0.0949, wR2 = 0.1805
Absolute structure parameter 0.03(3)
Largest diff. peak and hole 0.685 and -0.539 e-/Å3
168
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x 103) for
Co(C4H7N2O2)2(C7H10N2)(C19H23O6). U(eq) is defined as one third of the trace of the orthogonalized Uij
tensor.
______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
Co(1) 3542(1) -473(1) 5166(1) 32(1)
O(1) 733(6) -367(2) 5972(4) 55(2)
O(2) 4392(5) -285(2) 3290(3) 39(1)
O(3) 6271(5) -645(2) 4299(3) 40(1)
O(4) 2713(6) -620(2) 7043(3) 48(1)
O(5) 5215(6) 1654(2) 6951(4) 57(2)
O(6) 5342(8) 1832(2) 5445(4) 80(2)
O(7) 1545(12) 1494(4) 3589(9) 146(4)
O(8) -171(10) 1150(3) 4303(6) 105(3)
O(9) 58(6) 1689(2) 5894(5) 70(2)
O(10) 592(6) 1503(2) 7598(4) 58(2)
N(1) 1552(6) -316(2) 5218(6) 43(1)
N(2) 3296(6) -280(2) 3932(4) 32(1)
N(3) 5497(5) -646(2) 5113(5) 35(1)
N(4) 3801(6) -634(2) 6414(4) 37(1)
C(1) 963(8) -162(2) 4448(5) 38(2)
C(2) 2019(8) -147(2) 3663(5) 37(2)
C(3) 6054(7) -794(3) 5869(5) 38(2)
C(4) 5064(9) -783(3) 6655(5) 43(2)
C(5) -580(8) -31(3) 4352(8) 68(3)
C(6) 1640(9) 22(3) 2708(6) 57(2)
C(7) 7584(8) -993(3) 5925(6) 52(2)
C(8) 5397(10) -911(3) 7628(6) 64(2)
N(5) 2972(5) -1127(2) 4834(4) 34(1)
N(6) 1764(8) -2454(2) 4162(5) 63(2)
C(9) 3260(8) -1322(2) 4018(5) 44(2)
C(10) 2894(8) -1739(3) 3729(6) 49(2)
C(11) 2163(8) -2033(3) 4393(6) 50(2)
C(12) 1920(7) -1841(2) 5252(6) 49(2)
C(13) 2297(8) -1405(2) 5434(4) 41(2)
169
C(14) 1050(12) -2734(4) 4813(8) 92(4)
C(15) 1913(14) -2611(4) 3146(8) 98(4)
C(16) 4097(7) 154(2) 5515(4) 33(2)
C(17) 5233(6) 364(2) 5152(6) 36(1)
C(18) 5722(7) 838(2) 5361(5) 39(2)
C(19) 4410(7) 1114(2) 5793(5) 38(2)
C(20) 3781(7) 840(2) 6595(5) 33(2)
C(21) 3131(7) 391(2) 6228(5) 35(2)
C(22) 3304(8) 1193(2) 5025(5) 40(2)
C(23) 1919(7) 1307(2) 5124(6) 43(2)
C(24) 1126(8) 1446(2) 6017(5) 39(2)
C(25) 1564(7) 1315(2) 6950(4) 30(1)
C(26) 2681(7) 1059(2) 7215(5) 37(2)
C(27) 7095(8) 852(3) 5942(6) 51(2)
C(28) 5004(8) 1558(2) 6154(6) 44(2)
C(29) 6028(16) 2267(5) 5669(12) 137(5)
C(30) 7090(20) 2404(7) 5076(16) 195(8)
C(31) 995(13) 1311(5) 4216(10) 106(5)
C(32) -1044(16) 1148(5) 3436(10) 129(6)
C(33) -1767(13) 1553(5) 3320(8) 103(4)
C(34) 757(12) 1365(4) 8534(7) 90(3)
______________________________________________________________________________
170
Table 3. Bond lengths [Å] and angles [°] for Co(C4H7N2O2)2(C7H10N2)(C19H23O6)
_____________________________________________________
Co(1)-N(4) 1.864(6)
Co(1)-N(2) 1.869(5)
Co(1)-N(3) 1.872(5)
Co(1)-N(1) 1.890(5)
Co(1)-C(16) 1.987(6)
Co(1)-N(5) 2.058(6)
O(1)-N(1) 1.325(9)
O(2)-N(2) 1.365(7)
O(3)-N(3) 1.365(7)
O(4)-N(4) 1.347(7)
O(5)-C(28) 1.192(9)
O(6)-C(28) 1.335(9)
O(6)-C(29) 1.468(16)
O(7)-C(31) 1.164(14)
O(8)-C(31) 1.180(12)
O(8)-C(32) 1.479(12)
O(9)-C(24) 1.228(9)
O(10)-C(25) 1.403(8)
O(10)-C(34) 1.409(11)
N(1)-C(1) 1.310(10)
N(2)-C(2) 1.297(9)
N(3)-C(3) 1.275(9)
N(4)-C(4) 1.290(9)
C(1)-C(5) 1.478(10)
C(1)-C(2) 1.486(10)
C(2)-C(6) 1.497(10)
C(3)-C(4) 1.449(10)
C(3)-C(7) 1.528(10)
C(4)-C(8) 1.476(10)
N(5)-C(9) 1.330(9)
N(5)-C(13) 1.341(8)
N(6)-C(11) 1.339(9)
N(6)-C(14) 1.410(12)
N(6)-C(15) 1.533(12)
171
C(9)-C(10) 1.342(10)
C(10)-C(11) 1.453(11)
C(11)-C(12) 1.373(11)
C(12)-C(13) 1.359(10)
C(16)-C(17) 1.321(9)
C(16)-C(21) 1.523(9)
C(17)-C(18) 1.502(9)
C(18)-C(27) 1.514(10)
C(18)-C(19) 1.583(9)
C(19)-C(22) 1.515(10)
C(19)-C(28) 1.513(9)
C(19)-C(20) 1.521(10)
C(20)-C(26) 1.495(9)
C(20)-C(21) 1.547(9)
C(22)-C(23) 1.325(9)
C(23)-C(24) 1.529(11)
C(23)-C(31) 1.553(16)
C(24)-C(25) 1.448(10)
C(25)-C(26) 1.331(9)
C(29)-C(30) 1.35(2)
C(32)-C(33) 1.377(15)
N(4)-Co(1)-N(2) 177.0(3)
N(4)-Co(1)-N(3) 81.2(3)
N(2)-Co(1)-N(3) 99.3(3)
N(4)-Co(1)-N(1) 98.5(3)
N(2)-Co(1)-N(1) 81.1(3)
N(3)-Co(1)-N(1) 178.3(2)
N(4)-Co(1)-C(16) 87.9(2)
N(2)-Co(1)-C(16) 89.1(2)
N(3)-Co(1)-C(16) 91.0(2)
N(1)-Co(1)-C(16) 90.6(2)
N(4)-Co(1)-N(5) 90.8(2)
N(2)-Co(1)-N(5) 92.2(2)
N(3)-Co(1)-N(5) 88.8(2)
N(1)-Co(1)-N(5) 89.6(2)
172
C(16)-Co(1)-N(5) 178.7(2)
C(28)-O(6)-C(29) 117.6(9)
C(31)-O(8)-C(32) 114.0(12)
C(25)-O(10)-C(34) 116.5(6)
C(1)-N(1)-O(1) 119.4(6)
C(1)-N(1)-Co(1) 116.9(6)
O(1)-N(1)-Co(1) 123.7(6)
C(2)-N(2)-O(2) 118.2(5)
C(2)-N(2)-Co(1) 118.8(5)
O(2)-N(2)-Co(1) 123.0(4)
C(3)-N(3)-O(3) 121.0(5)
C(3)-N(3)-Co(1) 116.5(5)
O(3)-N(3)-Co(1) 122.4(4)
C(4)-N(4)-O(4) 120.0(6)
C(4)-N(4)-Co(1) 117.3(5)
O(4)-N(4)-Co(1) 122.6(5)
N(1)-C(1)-C(5) 124.5(8)
N(1)-C(1)-C(2) 112.1(6)
C(5)-C(1)-C(2) 123.4(8)
N(2)-C(2)-C(1) 111.0(6)
N(2)-C(2)-C(6) 125.7(7)
C(1)-C(2)-C(6) 123.2(7)
N(3)-C(3)-C(4) 113.5(6)
N(3)-C(3)-C(7) 123.2(7)
C(4)-C(3)-C(7) 123.2(7)
N(4)-C(4)-C(3) 111.5(6)
N(4)-C(4)-C(8) 121.8(7)
C(3)-C(4)-C(8) 126.7(7)
C(9)-N(5)-C(13) 112.9(6)
C(9)-N(5)-Co(1) 124.0(5)
C(13)-N(5)-Co(1) 123.1(4)
C(11)-N(6)-C(14) 120.7(8)
C(11)-N(6)-C(15) 119.5(8)
C(14)-N(6)-C(15) 119.4(8)
N(5)-C(9)-C(10) 128.2(7)
C(9)-C(10)-C(11) 117.6(7)
173
N(6)-C(11)-C(12) 124.1(8)
N(6)-C(11)-C(10) 121.3(8)
C(12)-C(11)-C(10) 114.5(7)
C(13)-C(12)-C(11) 121.4(8)
N(5)-C(13)-C(12) 125.2(7)
C(17)-C(16)-C(21) 120.6(6)
C(17)-C(16)-Co(1) 122.8(5)
C(21)-C(16)-Co(1) 116.5(4)
C(16)-C(17)-C(18) 126.6(6)
C(17)-C(18)-C(27) 112.6(6)
C(17)-C(18)-C(19) 109.3(5)
C(27)-C(18)-C(19) 114.0(6)
C(22)-C(19)-C(28) 111.0(5)
C(22)-C(19)-C(20) 112.0(6)
C(28)-C(19)-C(20) 110.0(6)
C(22)-C(19)-C(18) 107.9(6)
C(28)-C(19)-C(18) 107.8(6)
C(20)-C(19)-C(18) 108.1(5)
C(26)-C(20)-C(19) 118.3(5)
C(26)-C(20)-C(21) 108.2(5)
C(19)-C(20)-C(21) 110.4(5)
C(16)-C(21)-C(20) 113.3(5)
C(23)-C(22)-C(19) 127.4(7)
C(22)-C(23)-C(24) 128.0(8)
C(22)-C(23)-C(31) 116.1(8)
C(24)-C(23)-C(31) 115.9(7)
O(9)-C(24)-C(25) 120.7(7)
O(9)-C(24)-C(23) 114.8(7)
C(25)-C(24)-C(23) 124.5(6)
C(26)-C(25)-O(10) 121.8(6)
C(26)-C(25)-C(24) 129.0(6)
O(10)-C(25)-C(24) 109.1(6)
C(25)-C(26)-C(20) 126.9(6)
O(5)-C(28)-O(6) 123.2(7)
O(5)-C(28)-C(19) 126.3(7)
O(6)-C(28)-C(19) 110.5(7)
174
C(30)-C(29)-O(6) 115.7(16)
O(7)-C(31)-O(8) 131.6(15)
O(7)-C(31)-C(23) 114.3(13)
O(8)-C(31)-C(23) 113.9(10)
C(33)-C(32)-O(8) 111.1(10)
_____________________________________________________________
175
Table 4. Anisotropic displacement parameters (Å2x 103) for Co(C4H7N2O2)2(C7H10N2)(C19H23O6). The
anisotropic displacement factor exponent takes the form: -2Π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]
______________________________________________________________________________
U11 U22 U33 U23 U13 U12
______________________________________________________________________________
Co(1) 36(1) 32(1) 28(1) -5(1) 5(1) -2(1)
O(1) 49(3) 48(3) 68(4) -7(3) 35(3) -7(2)
O(2) 49(3) 41(3) 26(3) 3(2) 6(2) 5(2)
O(3) 37(3) 43(3) 39(3) -9(2) 18(2) 1(2)
O(4) 64(4) 45(3) 35(3) -6(2) 21(3) -8(3)
O(5) 64(4) 56(3) 51(4) -26(3) -8(3) -12(3)
O(6) 134(6) 31(3) 76(5) -3(3) 5(4) -29(3)
O(8) 112(7) 117(6) 86(6) 24(4) -67(5) -23(5)
O(9) 55(3) 76(4) 78(4) 18(3) -1(3) 32(3)
O(10) 55(3) 68(4) 52(4) -11(3) 3(3) 28(3)
N(1) 43(3) 39(3) 49(4) -13(4) 11(4) -5(2)
N(2) 34(3) 27(3) 34(3) 4(2) 2(3) -1(2)
N(3) 44(3) 30(3) 31(3) -1(3) -9(3) -2(2)
N(4) 47(4) 40(3) 25(3) 2(3) 6(3) -15(3)
C(1) 39(4) 23(4) 51(5) -11(3) -6(4) -1(3)
C(2) 42(4) 32(4) 39(4) -14(3) 6(3) -9(3)
C(3) 32(4) 47(4) 34(4) -4(3) -4(3) -11(3)
C(4) 58(5) 44(4) 26(4) -2(3) -21(4) -10(4)
C(5) 45(5) 49(5) 110(8) -25(5) -1(5) 4(4)
C(6) 69(6) 44(4) 57(6) 7(4) -9(4) 13(4)
C(7) 50(5) 45(4) 61(5) 7(4) -18(4) -2(3)
C(8) 94(7) 58(5) 39(5) 9(4) -15(5) -2(5)
N(5) 27(3) 37(3) 37(3) 1(2) -1(2) -4(2)
N(6) 75(5) 34(4) 80(5) -18(4) 3(4) -15(3)
C(9) 50(4) 35(4) 46(5) -2(3) 22(4) -3(3)
C(10) 49(4) 47(5) 51(5) -6(4) 9(4) 5(4)
C(11) 57(5) 39(4) 53(5) -14(4) -11(4) -2(4)
C(12) 49(4) 48(4) 50(5) -4(4) -10(4) -10(3)
C(13) 62(5) 41(4) 21(4) -5(3) -10(3) 0(4)
C(14) 92(7) 59(6) 124(11) -6(6) 6(6) -31(5)
C(15) 133(10) 74(7) 88(9) -25(6) -17(7) -17(7)
176
C(16) 39(4) 34(4) 27(3) -3(3) -7(3) -1(3)
C(17) 43(3) 34(3) 31(3) -14(4) 8(4) -2(3)
C(18) 45(4) 38(4) 35(5) -1(3) 13(3) -8(3)
C(19) 43(4) 28(4) 42(4) -10(3) -1(3) 8(3)
C(20) 33(4) 33(4) 33(4) -5(3) -1(3) 5(3)
C(21) 35(4) 36(4) 36(4) -2(3) 8(3) -7(3)
C(22) 65(5) 31(3) 25(4) -2(3) -16(4) -2(3)
C(23) 54(4) 37(4) 39(4) -3(4) 3(5) -3(3)
C(24) 30(4) 45(4) 41(5) 3(4) -5(3) -8(3)
C(25) 35(4) 33(4) 23(3) -2(3) 4(3) 5(3)
C(26) 47(4) 38(4) 27(4) -10(3) -2(3) 3(3)
C(27) 44(4) 60(5) 48(5) -11(4) 8(4) -2(4)
C(28) 41(4) 36(4) 55(5) -9(4) -7(4) -5(3)
C(31) 50(6) 133(11) 136(12) 98(10) 3(7) 20(7)
C(32) 140(12) 109(10) 139(12) -42(9) -96(10) 29(9)
C(33) 98(9) 121(10) 92(9) -19(7) -14(7) 32(7)
C(34) 88(7) 110(9) 72(8) 2(6) 31(6) 35(7)
______________________________________________________________________________
177
Table 5. Hydrogen coordinates (x 104) and isotropic displacement parameters (Å2x 10 3)
for Co(C4H7N2O2)2(C7H10N2)(C19H23O6)
_____________________________________________________________________________
x y z U(eq)
_____________________________________________________________________________
H(2O) 5060(80) -470(20) 3670(50) 39(19)
H(4O) 1590(80) -580(20) 6750(50) 42(19)
H(5A) -1059 -51 4962 102
H(5B) -1063 -235 3911 102
H(5C) -641 281 4121 102
H(6A) 2508 16 2312 85
H(6B) 1276 333 2753 85
H(6C) 888 -172 2436 85
H(7A) 7757 -1188 5382 78
H(7B) 7678 -1172 6499 78
H(7C) 8299 -748 5931 78
H(8A) 5285 -646 8034 96
H(8B) 6399 -1021 7666 96
H(8C) 4728 -1149 7831 96
H(9) 3792 -1144 3585 52
H(10) 3106 -1838 3113 59
H(12) 1478 -2017 5730 59
H(13) 2064 -1288 6034 49
H(14A) 1713 -2805 5329 138
H(14B) 751 -3016 4506 138
H(14C) 191 -2578 5056 138
H(15A) 2926 -2578 2944 147
H(15B) 1285 -2426 2745 147
H(15C) 1623 -2929 3098 147
H(17) 5797 198 4714 43
H(18) 5959 983 4748 47
H(20) 4619 755 7004 39
H(21A) 2967 184 6762 43
H(21B) 2175 454 5938 43
H(22) 3642 1156 4403 49
178
H(26) 2790 1011 7868 45
H(27A) 7880 697 5608 76
H(27B) 6922 701 6541 76
H(27C) 7373 1168 6054 76
H(29A) 5262 2502 5684 165
H(29B) 6446 2246 6305 165
H(30A) 7938 2501 5435 293
H(30B) 6730 2658 4700 293
H(30C) 7356 2153 4664 293
H(32A) -398 1096 2894 155
H(32B) -1758 898 3461 155
H(33A) -2450 1527 2797 155
H(33B) -1063 1793 3188 155
H(33C) -2302 1626 3892 155
H(34A) -10 1502 8915 135
H(34B) 1709 1462 8766 135
H(34C) 686 1035 8571 135
_____________________________________________________________________________
179
Table 6. Torsion angles [°] for Co(C4H7N2O2)2(C7H10N2)(C19H23O6)
________________________________________________________________
N(4)-Co(1)-N(1)-C(1) 177.3(5)
N(2)-Co(1)-N(1)-C(1) 0.3(5)
N(3)-Co(1)-N(1)-C(1) -103(12)
C(16)-Co(1)-N(1)-C(1) 89.3(5)
N(5)-Co(1)-N(1)-C(1) -92.0(5)
N(4)-Co(1)-N(1)-O(1) -4.8(5)
N(2)-Co(1)-N(1)-O(1) 178.2(5)
N(3)-Co(1)-N(1)-O(1) 75(12)
C(16)-Co(1)-N(1)-O(1) -92.7(5)
N(5)-Co(1)-N(1)-O(1) 86.0(5)
N(4)-Co(1)-N(2)-C(2) -85(5)
N(3)-Co(1)-N(2)-C(2) 177.0(5)
N(1)-Co(1)-N(2)-C(2) -1.4(5)
C(16)-Co(1)-N(2)-C(2) -92.1(5)
N(5)-Co(1)-N(2)-C(2) 87.9(5)
N(4)-Co(1)-N(2)-O(2) 97(5)
N(3)-Co(1)-N(2)-O(2) -1.0(5)
N(1)-Co(1)-N(2)-O(2) -179.4(5)
C(16)-Co(1)-N(2)-O(2) 89.9(5)
N(5)-Co(1)-N(2)-O(2) -90.1(5)
N(4)-Co(1)-N(3)-C(3) 2.0(5)
N(2)-Co(1)-N(3)-C(3) 178.9(5)
N(1)-Co(1)-N(3)-C(3) -78(12)
C(16)-Co(1)-N(3)-C(3) 89.7(5)
N(5)-Co(1)-N(3)-C(3) -89.1(5)
N(4)-Co(1)-N(3)-O(3) 177.7(4)
N(2)-Co(1)-N(3)-O(3) -5.3(4)
N(1)-Co(1)-N(3)-O(3) 98(12)
C(16)-Co(1)-N(3)-O(3) -94.6(4)
N(5)-Co(1)-N(3)-O(3) 86.7(4)
N(2)-Co(1)-N(4)-C(4) -99(5)
N(3)-Co(1)-N(4)-C(4) -1.0(5)
N(1)-Co(1)-N(4)-C(4) 177.3(5)
C(16)-Co(1)-N(4)-C(4) -92.4(5)
180
N(5)-Co(1)-N(4)-C(4) 87.6(5)
N(2)-Co(1)-N(4)-O(4) 84(5)
N(3)-Co(1)-N(4)-O(4) -177.6(5)
N(1)-Co(1)-N(4)-O(4) 0.7(5)
C(16)-Co(1)-N(4)-O(4) 91.0(5)
N(5)-Co(1)-N(4)-O(4) -89.0(5)
O(1)-N(1)-C(1)-C(5) 0.9(10)
Co(1)-N(1)-C(1)-C(5) 178.9(5)
O(1)-N(1)-C(1)-C(2) -177.4(5)
Co(1)-N(1)-C(1)-C(2) 0.6(7)
O(2)-N(2)-C(2)-C(1) -179.9(5)
Co(1)-N(2)-C(2)-C(1) 2.0(7)
O(2)-N(2)-C(2)-C(6) -2.6(9)
Co(1)-N(2)-C(2)-C(6) 179.3(5)
N(1)-C(1)-C(2)-N(2) -1.6(8)
C(5)-C(1)-C(2)-N(2) -179.9(6)
N(1)-C(1)-C(2)-C(6) -179.0(6)
C(5)-C(1)-C(2)-C(6) 2.7(10)
O(3)-N(3)-C(3)-C(4) -178.3(5)
Co(1)-N(3)-C(3)-C(4) -2.5(8)
O(3)-N(3)-C(3)-C(7) -2.1(10)
Co(1)-N(3)-C(3)-C(7) 173.7(5)
O(4)-N(4)-C(4)-C(3) 176.7(6)
Co(1)-N(4)-C(4)-C(3) 0.0(8)
O(4)-N(4)-C(4)-C(8) -4.6(10)
Co(1)-N(4)-C(4)-C(8) 178.7(6)
N(3)-C(3)-C(4)-N(4) 1.6(9)
C(7)-C(3)-C(4)-N(4) -174.6(6)
N(3)-C(3)-C(4)-C(8) -177.1(7)
C(7)-C(3)-C(4)-C(8) 6.8(12)
N(4)-Co(1)-N(5)-C(9) -147.4(6)
N(2)-Co(1)-N(5)-C(9) 32.9(6)
N(3)-Co(1)-N(5)-C(9) -66.3(6)
N(1)-Co(1)-N(5)-C(9) 114.0(6)
C(16)-Co(1)-N(5)-C(9) -147(11)
N(4)-Co(1)-N(5)-C(13) 31.0(5)
181
N(2)-Co(1)-N(5)-C(13) -148.7(5)
N(3)-Co(1)-N(5)-C(13) 112.1(5)
N(1)-Co(1)-N(5)-C(13) -67.6(6)
C(16)-Co(1)-N(5)-C(13) 31(11)
C(13)-N(5)-C(9)-C(10) 3.8(11)
Co(1)-N(5)-C(9)-C(10) -177.7(6)
N(5)-C(9)-C(10)-C(11) -3.9(12)
C(14)-N(6)-C(11)-C(12) -0.3(13)
C(15)-N(6)-C(11)-C(12) 172.0(9)
C(14)-N(6)-C(11)-C(10) -179.7(9)
C(15)-N(6)-C(11)-C(10) -7.4(12)
C(9)-C(10)-C(11)-N(6) -179.9(7)
C(9)-C(10)-C(11)-C(12) 0.6(11)
N(6)-C(11)-C(12)-C(13) -177.3(7)
C(10)-C(11)-C(12)-C(13) 2.2(11)
C(9)-N(5)-C(13)-C(12) -0.4(10)
Co(1)-N(5)-C(13)-C(12) -179.0(5)
C(11)-C(12)-C(13)-N(5) -2.5(11)
N(4)-Co(1)-C(16)-C(17) 119.7(6)
N(2)-Co(1)-C(16)-C(17) -60.7(6)
N(3)-Co(1)-C(16)-C(17) 38.6(6)
N(1)-Co(1)-C(16)-C(17) -141.8(6)
N(5)-Co(1)-C(16)-C(17) 119(11)
N(4)-Co(1)-C(16)-C(21) -60.9(5)
N(2)-Co(1)-C(16)-C(21) 118.7(5)
N(3)-Co(1)-C(16)-C(21) -142.1(5)
N(1)-Co(1)-C(16)-C(21) 37.6(5)
N(5)-Co(1)-C(16)-C(21) -61(11)
C(21)-C(16)-C(17)-C(18) -0.4(11)
Co(1)-C(16)-C(17)-C(18) 179.0(5)
C(16)-C(17)-C(18)-C(27) 107.8(8)
C(16)-C(17)-C(18)-C(19) -20.0(10)
C(17)-C(18)-C(19)-C(22) -70.2(7)
C(27)-C(18)-C(19)-C(22) 162.7(6)
C(17)-C(18)-C(19)-C(28) 169.9(6)
C(27)-C(18)-C(19)-C(28) 42.9(8)
182
C(17)-C(18)-C(19)-C(20) 51.0(7)
C(27)-C(18)-C(19)-C(20) -76.0(7)
C(22)-C(19)-C(20)-C(26) -70.9(7)
C(28)-C(19)-C(20)-C(26) 53.0(8)
C(18)-C(19)-C(20)-C(26) 170.4(6)
C(22)-C(19)-C(20)-C(21) 54.5(7)
C(28)-C(19)-C(20)-C(21) 178.4(5)
C(18)-C(19)-C(20)-C(21) -64.2(7)
C(17)-C(16)-C(21)-C(20) -11.0(9)
Co(1)-C(16)-C(21)-C(20) 169.6(4)
C(26)-C(20)-C(21)-C(16) 174.8(6)
C(19)-C(20)-C(21)-C(16) 43.9(8)
C(28)-C(19)-C(22)-C(23) -80.2(9)
C(20)-C(19)-C(22)-C(23) 43.2(9)
C(18)-C(19)-C(22)-C(23) 162.0(6)
C(19)-C(22)-C(23)-C(24) 8.5(11)
C(19)-C(22)-C(23)-C(31) -173.3(8)
C(22)-C(23)-C(24)-O(9) 154.1(7)
C(31)-C(23)-C(24)-O(9) -24.1(10)
C(22)-C(23)-C(24)-C(25) -25.4(11)
C(31)-C(23)-C(24)-C(25) 156.4(8)
C(34)-O(10)-C(25)-C(26) -7.1(11)
C(34)-O(10)-C(25)-C(24) 172.7(8)
O(9)-C(24)-C(25)-C(26) -179.7(7)
C(23)-C(24)-C(25)-C(26) -0.2(11)
O(9)-C(24)-C(25)-O(10) 0.6(9)
C(23)-C(24)-C(25)-O(10) -179.9(6)
O(10)-C(25)-C(26)-C(20) 179.7(6)
C(24)-C(25)-C(26)-C(20) 0.0(12)
C(19)-C(20)-C(26)-C(25) 43.6(10)
C(21)-C(20)-C(26)-C(25) -82.7(8)
C(29)-O(6)-C(28)-O(5) 1.0(13)
C(29)-O(6)-C(28)-C(19) -176.0(9)
C(22)-C(19)-C(28)-O(5) 137.7(8)
C(20)-C(19)-C(28)-O(5) 13.2(10)
C(18)-C(19)-C(28)-O(5) -104.5(9)
183
C(22)-C(19)-C(28)-O(6) -45.5(8)
C(20)-C(19)-C(28)-O(6) -170.0(6)
C(18)-C(19)-C(28)-O(6) 72.4(7)
C(28)-O(6)-C(29)-C(30) 141.5(15)
C(32)-O(8)-C(31)-O(7) 6(2)
C(32)-O(8)-C(31)-C(23) -179.2(9)
C(22)-C(23)-C(31)-O(7) -46.6(15)
C(24)-C(23)-C(31)-O(7) 131.9(12)
C(22)-C(23)-C(31)-O(8) 137.4(11)
C(24)-C(23)-C(31)-O(8) -44.2(14)
C(31)-O(8)-C(32)-C(33) -85.3(17)
________________________________________________________________
184
Table 7. Hydrogen bonds for Co(C4H7N2O2)2(C7H10N2)(C19H23O6) [Å and °].
____________________________________________________________________________
D-H...A d(D-H) d(H...A) d(D...A) <(DHA)
____________________________________________________________________________
O(2)-H(2O)...O(3) 0.98(7) 1.53(8) 2.491(7) 167(6)
O(4)-H(4O)...O(1) 1.12(7) 1.49(8) 2.495(8) 145(6)
____________________________________________________________________________
Least-squares planes (x,y,z in crystal coordinates) and deviations from them
(* indicates atom used to define plane)
2.4011 (0.0155) x + 27.6265 (0.0177) y + 3.4470 (0.0266) z = 1.3329 (0.0144)
* -0.0357 (0.0027) N1
* 0.0400 (0.0029) N2
* -0.0359 (0.0026) N3
* 0.0403 (0.0028) N4
* -0.0087 (0.0023) Co1
-2.0669 (0.0059) N5
1.9782 (0.0066) C16
Rms deviation of fitted atoms = 0.0342
185
Unit cell of 5.2.3b not showing Head-to-Tail packing
186
Appendix C
NMR Spectral Data of Silyl Dienes, 11.3.2b, 13.1.2a-c
187
1H NMR Spectra (Stacked) of
Various Silyl Dienes Showing Dienyl Region
(Enhanced upfield effect noticed by chemical shift of H1 seen in diene, 13.1.2c
can be explained by resonance effect of electron rich silicon)
SiO
NOO
(13.1.2a)
1
2
3
4
(EtO)3Si
(11.3.2b)
1
2
3
4
H1
H3H4
H1
H3
H1
H3
H4
H4
H4
Si
(13.1.2c)
1
23
4
O
O O
O
K
188
2D COSY 1H NMR Spectra of Triethoxy Silyl Diene, 11.3.2b
H1H3 H4(EtO)3Si
(11.3.2b)
2
3
4
1
189
2D COSY
1H NMR Spectra of Silatrane Substituted Diene, 13.1.2a
H3 H4H4H1
SiO
NOO
(13.1.2a)
2
3
4
1
190
2D COSY 1H NMR Spectra of Catechol Silane Substituted Diene, 13.1.2c
Si
(13.1.2c)
1
2
3
4
O
OO O
K
H1
H3H4 H4
191
Me2PhSi
2
1
34
(13.1.2b)
H3H1
H4H1
NOE between H1 H3
2D NOESY 1H NMR Spectra of 13.1.2b: Exhibits S-trans
Conformation in solution due to a Strong NOE observed between H1, H3
192
2D NOESY
1H NMR Spectra of Catechol Silane Substituted Diene, 13.1.2c:
No peak distinction in between H3 and H1/H4 due to overlapping
H3
H1
H4
No distinction in between the cross-peaks from H1 to H4
(or) H1 to H3 to prove S-cis vs S-trans conformer
Si
(13.1.2c)
1
2
3
4
O
OO O
K
193
Variable Temperature H NMR Experiments of 13.1.2a
(No peak broadening even at –50 ⁰C)
Si1
2
3
4
13.1.2a
O
N
O
O
H3
H1
H4
194
Appendix D
Crystallographic Data for 13.1.2a
195
Table 1. Crystal data and structure refinement for C10H17NO3Si
Empirical formula C10 H17 N O3 Si
Formula weight 227.34
Temperature 193(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic
Space group C2/c- C 62h
(No. 15)
Unit cell dimensions a = 21.502(3) Å
b = 12.376(2) Å, β = 107.412(2)°
c = 27.044(3) Å
Volume 6867.2(14) Å3
Z 24
Density (calculated) 1.319 g/cm3
Absorption coefficient 0.193 mm-1
F(000) 2928
Crystal size 0.50 x 0.45 x 0.05 mm3
Theta range for data collection 3.80 to 27.50°
Index ranges -27≤h≤27, -16≤k≤15, -35≤l≤35
Reflections collected 29884
Independent reflections 7854 [R(int) = 0.0393]
Completeness to theta = 27.50° 99.6 %
Absorption correction Multi-scan (SADABS)
Refinement method Full-matrix least-squares on F2
Data / parameters 7854 / 433
Goodness-of-fit on F2 1.040
Final R indices [6113 data I>2σ(I)] R1 = 0.0541, wR2 = 0.1309
R indices (all data) R1 = 0.0706, wR2 = 0.1411
Largest diff. peak and hole 0.692 and -0.359 e-/Å-3
196
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x 103)
for C10H17NO3Si. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
Si(1) 2831(1) 4635(1) 200(1) 28(1)
O(11) 2434(1) 3985(1) -339(1) 36(1)
O(12) 2723(1) 5964(1) 230(1) 33(1)
O(13) 3084(1) 3958(1) 752(1) 40(1)
N(1) 1902(1) 4565(1) 353(1) 33(1)
C(11) 1745(1) 3835(2) -494(1) 39(1)
C(12) 1531(1) 3737(2) -10(1) 41(1)
C(13) 2214(1) 6416(2) 400(1) 37(1)
C(14) 1632(1) 5660(2) 245(1) 38(1)
C(15) 2648(1) 3519(2) 1003(1) 44(1)
C(16) 2062(1) 4250(2) 901(1) 41(1)
C(17) 4163(1) 4141(2) 349(1) 51(1)
C(18) 3649(1) 4692(2) 62(1) 36(1)
C(19) 3738(1) 5341(2) -371(1) 48(1)
C(20) 3306(1) 5958(2) -694(1) 54(1)
Si(2) 2141(1) 190(1) 2430(1) 30(1)
O(21) 2375(1) -1070(1) 2371(1) 41(1)
O(22) 1779(1) 900(1) 1903(1) 42(1)
O(23) 2510(1) 855(1) 2970(1) 47(1)
N(2) 3011(1) 588(1) 2227(1) 32(1)
C(21) 2886(1) -1327(2) 2158(1) 44(1)
C(22) 3386(1) -429(2) 2285(1) 39(1)
C(23) 2127(1) 1494(2) 1622(1) 42(1)
C(24) 2775(1) 945(2) 1679(1) 39(1)
C(25) 3165(1) 1211(2) 3089(1) 50(1)
C(26) 3328(1) 1441(2) 2586(1) 41(1)
C(22') 3144(12) -278(18) 1981(10) 38(5)
C(24') 2850(9) 1636(15) 1964(7) 25(4)
C(26') 3507(10) 829(18) 2787(8) 30(5)
C(27) 1284(1) 42(3) 3045(1) 58(1)
C(28) 1369(1) -203(2) 2594(1) 38(1)
197
C(29) 853(1) -841(2) 2229(1) 49(1)
C(30) 789(1) -1055(2) 1744(1) 64(1)
Si(3) 4877(1) 8855(1) 1204(1) 36(1)
O(31) 5166(1) 8636(2) 711(1) 67(1)
O(32) 5361(1) 8635(1) 1797(1) 54(1)
O(33) 4077(1) 8838(1) 1106(1) 42(1)
N(3) 4768(1) 7132(2) 1189(1) 40(1)
C(31) 5134(2) 7613(3) 472(1) 81(1)
C(32) 5173(1) 6744(2) 875(1) 69(1)
C(33) 5544(1) 7583(2) 1994(1) 69(1)
C(34) 5007(1) 6799(2) 1735(1) 61(1)
C(35) 3722(1) 7877(2) 1113(1) 42(1)
C(36) 4067(1) 6941(2) 951(1) 38(1)
C(37) 5140(1) 10948(2) 890(2) 72(1)
C(38) 4960(1) 10380(2) 1235(1) 51(1)
C(39) 4808(2) 10927(2) 1699(2) 73(1)
C(40) 4532(2) 11847(3) 1708(2) 77(1)
_____________________________________________________________________________
198
Table 3. Bond lengths [Å] and angles [°] for C10H17NO3Si
______________________________________________________________________________
Si(1)-O(11) 1.659(2)
Si(1)-O(12) 1.666(1)
Si(1)-O(13) 1.655(2)
Si(1)-C(18) 1.907(2)
Si(1)-N(1) 2.158(2)
O(11)-C(11) 1.426(2)
O(12)-C(13) 1.422(2)
O(13)-C(15) 1.419(3)
N(1)-C(12) 1.478(3)
N(1)-C(14) 1.469(3)
N(1)-C(16) 1.468(3)
C(11)-C(12) 1.515(3)
C(13)-C(14) 1.518(3)
C(15)-C(16) 1.509(3)
C(17)-C(18) 1.332(3)
C(18)-C(19) 1.479(4)
C(19)-C(20) 1.312(4)
C(19)-H(19) 0.97(3)
Si(2)-O(22) 1.656(2)
Si(2)-O(23) 1.658(2)
Si(2)-O(21) 1.660(2)
Si(2)-C(28) 1.906(2)
Si(2)-N(2) 2.159(2)
O(21)-C(21) 1.419(3)
O(22)-C(23) 1.421(2)
O(23)-C(25) 1.417(3)
N(2)-C(22) 1.477(3)
N(2)-C(24) 1.482(3)
N(2)-C(26) 1.458(3)
C(21)-C(22) 1.513(3)
C(23)-C(24) 1.516(3)
C(25)-C(26) 1.528(4)
C(27)-C(28) 1.322(3)
C(28)-C(29) 1.474(4)
C(29)-C(30) 1.304(4)
C(29)-H(29) 0.99(3)
N(2)-C(22') 1.34(2)
N(2)-C(24') 1.47(2)
N(2)-C(26') 1.60(2)
C(21)-C(22') 1.54(2)
C(23)-C(24') 1.56(2)
C(25)-C(26') 1.34 (2)
Si(3)-O(31) 1.653(2)
Si(3)-O(32) 1.651(2)
Si(3)-O(33) 1.662(2)
Si(3)-C(38) 1.896(3)
199
Si(3)-N(3) 2.144(2)
O(31)-C(31) 1.413(3)
O(32)-C(33) 1.419(3)
O(33)-C(35) 1.415(3)
N(3)-C(32) 1.468(3)
N(3)-C(34) 1.470(3)
N(3)-C(36) 1.470(3)
C(31)-C(32) 1.515(5)
C(33)-C(34) 1.510(4)
C(35)-C(36) 1.509(3)
C(37)-C(38) 1.315(4)
C(38)-C(39) 1.545(5)
C(39)-C(40) 1.287(4)
C(39)-H(39) 0.74(4)
O(13)-Si(1)-O(11) 119.39(8)
O(13)-Si(1)-O(12) 117.96(8)
O(11)-Si(1)-O(12) 118.59(8)
O(13)-Si(1)-C(18) 96.95(9)
O(11)-Si(1)-C(18) 96.18(8)
O(12)-Si(1)-C(18) 97.07(8)
O(13)-Si(1)-N(1) 83.12(7)
O(11)-Si(1)-N(1) 83.55(7)
O(12)-Si(1)-N(1) 83.13(7)
C(18)-Si(1)-N(1) 179.72(9)
O(22)-Si(2)-O(23) 118.13(9)
O(22)-Si(2)-O(21) 119.58(9)
O(23)-Si(2)-O(21) 118.20(9)
O(22)-Si(2)-C(28) 96.73(8)
O(23)-Si(2)-C(28) 98.17(9)
O(21)-Si(2)-C(28) 95.37(9)
O(22)-Si(2)-N(2) 83.14(7)
O(23)-Si(2)-N(2) 83.54(8)
O(21)-Si(2)-N(2) 83.07(7)
C(28)-Si(2)-N(2) 178.10(9)
C(11)-O(11)-Si(1) 122.43(13)
C(13)-O(12)-Si(1) 122.42(12)
C(15)-O(13)-Si(1) 122.57(14)
C(21)-O(21)-Si(2) 122.90(13)
C(23)-O(22)-Si(2) 123.16(13)
C(25)-O(23)-Si(2) 122.39(15)
C(16)-N(1)-C(14) 113.92(17)
C(16)-N(1)-C(12) 113.77(17)
C(14)-N(1)-C(12) 113.82(17)
C(16)-N(1)-Si(1) 104.74(13)
C(14)-N(1)-Si(1) 104.89(12)
C(12)-N(1)-Si(1) 104.30(13)
C(26)-N(2)-C(22) 114.55(19)
C(26)-N(2)-C(24) 113.77(18)
C(22)-N(2)-C(24) 111.92(19)
C(26)-N(2)-Si(2) 105.22(14)
C(22)-N(2)-Si(2) 105.30(13)
C(24)-N(2)-Si(2) 104.96(13)
O(11)-C(11)-C(12) 108.35(17)
N(1)-C(12)-C(11) 105.98(16)
O(12)-C(13)-C(14) 108.49(16)
O(21)-C(21)-C(22) 109.03(19)
N(2)-C(22)-C(21) 105.93(18)
O(22)-C(23)-C(24) 109.20(17)
200
N(1)-C(14)-C(13) 105.69(17)
O(13)-C(15)-C(16) 108.57(17)
N(1)-C(16)-C(15) 105.86(17)
N(2)-C(24)-C(23) 105.32(18)
O(23)-C(25)-C(26) 109.40(19)
N(2)-C(26)-C(25) 105.84(19)
C(17)-C(18)-C(19) 117.3(2)
C(17)-C(18)-Si(1) 121.31(19)
C(19)-C(18)-Si(1) 121.38(17)
C(20)-C(19)-C(18) 127.5(2)
C(20)-C(19)-H(19) 117.9(16)
C(18)-C(19)-H(19) 114.5(16)
C(27)-C(28)-C(29) 117.1(2)
C(27)-C(28)-Si(2) 121.8(2)
C(29)-C(28)-Si(2) 121.03(17)
C(30)-C(29)-C(28) 127.8(2)
C(30)-C(29)-H(29) 120.5(17)
C(28)-C(29)-H(29) 111.7(17)
C(22')-N(2)-C(24') 121.4(13)
C(22')-N(2)-C(26') 116.1(14)
C(24')-N(2)-C(26') 106.7(11)
C(22')-N(2)-Si(2) 105.9(10)
C(24')-N(2)-Si(2) 103.2(7)
C(26')-N(2)-Si(2) 100.6(7)
N(2)-C(22')-C(21) 111.6(15)
N(2)-C(24')-C(23) 103.6(11)
C(25)-C(26')-N(2) 108.1(13)
O(21)-C(21)-C(22') 109.3(9)
O(22)-C(23)-C(24') 109.4(7)
C(26')-C(25)-O(23) 116.3(9)
O(32)-Si(3)-O(31) 118.51(12)
O(32)-Si(3)-O(33) 118.22(10)
O(31)-Si(3)-O(33) 119.39(10)
O(32)-Si(3)-C(38) 95.59(10)
O(31)-Si(3)-C(38) 98.44(12)
O(33)-Si(3)-C(38) 95.65(9)
O(32)-Si(3)-N(3) 83.55(8)
O(31)-Si(3)-N(3) 83.56(9)
O(33)-Si(3)-N(3) 83.18(7)
C(38)-Si(3)-N(3) 177.99(11)
C(31)-O(31)-Si(3) 122.48(17)
C(33)-O(32)-Si(3) 122.70(17)
C(35)-O(33)-Si(3) 123.01(13)
C(32)-N(3)-C(34) 113.6(2)
C(32)-N(3)-C(36) 113.7(2)
C(34)-N(3)-C(36) 113.57(19)
C(32)-N(3)-Si(3) 104.74(15)
C(34)-N(3)-Si(3) 104.91(14)
C(36)-N(3)-Si(3) 105.13(13)
O(31)-C(31)-C(32) 108.8(2)
O(32)-C(33)-C(34) 109.1(2)
O(33)-C(35)-C(36) 109.2(2)
N(3)-C(32)-C(31) 105.7 (2)
N(3)-C(34)-C(33) 105.9(2)
N(3)-C(36)-C(35) 106.0(2)
201
C(37)-C(38)-C(39) 121.4(3)
C(37)-C(38)-Si(3) 122.9(2)
C(39)-C(38)-Si(3) 115.6(2)
C(40)-C(39)-C(38) 127.9(4)
C(40)-C(39)-H(39) 108(3)
C(38)-C(39)-H(39) 124(3)
202
__________________________________________________________________________
203
Table 4. Anisotropic displacement parameters (Å2x 103) for C10H17NO3Si. The anisotropic
displacement factor exponent takes the form: -2Π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]
______________________________________________________________________________
U11 U22 U33 U23 U13 U12
______________________________________________________________________________
Si(1) 26(1) 23(1) 34(1) -3(1) 10(1) -2(1)
O(11) 31(1) 35(1) 44(1) -12(1) 13(1) -7(1)
O(12) 32(1) 24(1) 48(1) -4(1) 19(1) -3(1)
O(13) 37(1) 39(1) 43(1) 6(1) 11(1) 2(1)
N(1) 33(1) 29(1) 39(1) -1(1) 13(1) -5(1)
C(11) 31(1) 37(1) 46(1) -10(1) 6(1) -7(1)
C(12) 32(1) 39(1) 53(1) -4(1) 12(1) -11(1)
C(13) 37(1) 29(1) 49(1) -3(1) 20(1) 2(1)
C(14) 31(1) 36(1) 50(1) -1(1) 18(1) 3(1)
C(15) 54(1) 35(1) 43(1) 8(1) 17(1) -4(1)
C(16) 49(1) 40(1) 42(1) 3(1) 23(1) -7(1)
C(17) 33(1) 45(1) 76(2) -11(1) 19(1) 1(1)
C(18) 30(1) 30(1) 49(1) -14(1) 15(1) -5(1)
C(19) 42(1) 51(2) 62(2) -15(1) 31(1) -11(1)
C(20) 67(2) 54(2) 54(2) -3(1) 36(1) -7(1)
Si(2) 27(1) 28(1) 37(1) 7(1) 12(1) 4(1)
O(21) 35(1) 28(1) 67(1) 7(1) 25(1) 4(1)
O(22) 28(1) 48(1) 52(1) 22(1) 13(1) 4(1)
O(23) 43(1) 55(1) 46(1) -8(1) 19(1) -7(1)
N(2) 27(1) 29(1) 39(1) 6(1) 10(1) 3(1)
C(21) 35(1) 31(1) 71(2) 2(1) 25(1) 5(1)
C(22) 30(1) 34(1) 56(2) 8(1) 16(1) 7(1)
C(23) 31(1) 46(1) 49(1) 22(1) 12(1) 2(1)
C(24) 33(1) 46(2) 39(1) 11(1) 13(1) -1(1)
C(25) 45(1) 58(2) 43(1) -5(1) 6(1) -12(1)
C(26) 36(1) 38(1) 47(2) -1(1) 10(1) -6(1)
C(27) 45(1) 73(2) 64(2) 11(2) 31(1) 9(1)
C(28) 34(1) 36(1) 50(1) 14(1) 21(1) 10(1)
C(29) 35(1) 43(1) 74(2) 15(1) 26(1) 0(1)
C(30) 48(2) 62(2) 86(2) -18(2) 28(2) -22(1)
Si(3) 28(1) 33(1) 46(1) -5(1) 7(1) -5(1)
204
O(31) 85(1) 53(1) 83(1) -18(1) 55(1) -26(1)
O(32) 44(1) 40(1) 60(1) -3(1) -11(1) -3(1)
O(33) 29(1) 32(1) 59(1) -4(1) 5(1) -3(1)
N(3) 29(1) 33(1) 56(1) -6(1) 12(1) -2(1)
C(31) 99(2) 68(2) 111(3) -38(2) 83(2) -34(2)
C(32) 49(2) 49(2) 122(3) -33(2) 46(2) -10(1)
C(33) 53(2) 50(2) 79(2) 9(1) -17(2) -3(1)
C(34) 56(2) 41(1) 69(2) 10(1) -7(1) -2(1)
C(35) 31(1) 38(1) 57(1) -7(1) 12(1) -6(1)
C(36) 33(1) 35(1) 45(1) -6(1) 10(1) -6(1)
C(37) 50(2) 49(2) 113(3) 10(2) 17(2) -11(1)
C(38) 30(1) 37(1) 76(2) -1(1) -1(1) -7(1)
C(39) 43(2) 38(2) 115(3) -32(2) -9(2) -5(1)
C(40) 64(2) 76(2) 91(2) -22(2) 26(2) -18(2)
______________________________________________________________________________
205
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3)
for C10H17NO3Si
______________________________________________________________________________
x y z U(eq)
_____________________________________________________________________________
H(11A) 1627 3172 -706 47
H(11B) 1525 4457 -704 47
H(12A) 1057 3869 -93 50
H(12B) 1629 3006 142 50
H(13A) 2091 7134 239 44
H(13B) 2363 6509 781 44
H(14A) 1330 5813 449 45
H(14B) 1394 5742 -128 45
H(15A) 2866 3465 1380 52
H(15B) 2511 2786 868 52
H(16A) 1691 3863 966 50
H(16B) 2164 4895 1127 50
H(17A) 4565 4175 272 61
H(17B) 4127 3714 631 61
H(19) 4178(14) 5320(20) -402(10) 57
H(20A) 2880 6023 -662 65
H(20B) 3421 6339 -959 65
H(21A) 2708 -1410 1777 53
H(21B) 3092 -2018 2305 53
H(21C) 2721 -1820 1859 53
H(21D) 3243 -1697 2422 53
H(22A) 3677 -506 2644 47
H(22B) 3654 -444 2045 47
H(23A) 2202 2242 1758 51
H(23B) 1870 1529 1252 51
H(23C) 1923 2212 1528 51
H(23D) 2113 1106 1299 51
H(24A) 2718 318 1442 47
H(24B) 3087 1455 1600 47
H(25A) 3461 647 3290 60
H(25B) 3225 1874 3302 60
206
H(25C) 3164 2009 3070 60
H(25D) 3394 1007 3452 60
H(26A) 3159 2159 2447 49
H(26B) 3805 1427 2647 49
H(22C) 3622 -336 2049 46
H(22D) 2944 -186 1603 46
H(24C) 3138 1792 1747 30
H(24D) 2891 2228 2218 30
H(26C) 3737 158 2938 36
H(26D) 3836 1368 2760 36
H(27A) 902 -192 3122 66(8)
H(27B) 1604 453 3292 48(7)
H(29) 530(14) -1120(20) 2395(11) 68(9)
H(30A) 1099 -787 1588 76(9)
H(30B) 432 -1480 1548 79(10)
H(31A) 5500 7532 323 98
H(31B) 4720 7544 188 98
H(32A) 5005 6049 707 83
H(32B) 5629 6641 1093 83
H(33A) 5619 7575 2374 82
H(33B) 5954 7367 1926 82
H(34A) 5177 6051 1764 73
H(34B) 4652 6833 1898 73
H(35A) 3276 7946 872 50
H(35B) 3690 7749 1465 50
H(36A) 3935 6250 1074 46
H(36B) 3960 6911 569 46
H(37A) 5179 11711 923 86
H(37B) 5231 10594 607 86
H(39) 4860(20) 10670(30) 1953(14) 87
H(40A) 4395 12274 1403 92
H(40B) 4465 12098 2020 92
______________________________________________________________________________
207
Table 6. Torsion angles [°] for C10H17NO3Si
________________________________________________________________
O(13)-Si(1)-O(11)-C(11) 87.51(17)
O(12)-Si(1)-O(11)-C(11) -69.38(18)
C(18)-Si(1)-O(11)-C(11) -170.91(17)
N(1)-Si(1)-O(11)-C(11) 9.16(16)
O(13)-Si(1)-O(12)-C(13) -69.08(18)
O(11)-Si(1)-O(12)-C(13) 88.13(17)
C(18)-Si(1)-O(12)-C(13) -170.84(17)
N(1)-Si(1)-O(12)-C(13) 9.35(16)
O(11)-Si(1)-O(13)-C(15) -68.49(18)
O(12)-Si(1)-O(13)-C(15) 88.54(17)
C(18)-Si(1)-O(13)-C(15) -169.63(17)
N(1)-Si(1)-O(13)-C(15) 10.10(16)
O(13)-Si(1)-N(1)-C(16) 15.04(13)
O(11)-Si(1)-N(1)-C(16) 135.78(14)
O(12)-Si(1)-N(1)-C(16) -104.31(14)
C(18)-Si(1)-N(1)-C(16) 120(26)
O(13)-Si(1)-N(1)-C(14) 135.30(14)
O(11)-Si(1)-N(1)-C(14) -103.97(14)
O(12)-Si(1)-N(1)-C(14) 15.94(13)
C(18)-Si(1)-N(1)-C(14) -120(35)
O(13)-Si(1)-N(1)-C(12) -104.77(14)
O(11)-Si(1)-N(1)-C(12) 15.96(14)
O(12)-Si(1)-N(1)-C(12) 135.88(14)
C(18)-Si(1)-N(1)-C(12) 0(26)
Si(1)-O(11)-C(11)-C(12) -32.1(2)
C(16)-N(1)-C(12)-C(11) -147.31(19)
C(14)-N(1)-C(12)-C(11) 79.9(2)
Si(1)-N(1)-C(12)-C(11) -33.79(19)
O(11)-C(11)-C(12)-N(1) 41.9(2)
Si(1)-O(12)-C(13)-C(14) -32.2(2)
C(16)-N(1)-C(14)-C(13) 80.2(2)
C(12)-N(1)-C(14)-C(13) -147.07(18)
Si(1)-N(1)-C(14)-C(13) -33.70(18)
O(12)-C(13)-C(14)-N(1) 41.8(2)
208
Si(1)-O(13)-C(15)-C(16) -32.8(2)
C(14)-N(1)-C(16)-C(15) -146.99(18)
C(12)-N(1)-C(16)-C(15) 80.3(2)
Si(1)-N(1)-C(16)-C(15) -32.95(19)
O(13)-C(15)-C(16)-N(1) 41.6(2)
O(13)-Si(1)-C(18)-C(17) 8.1(2)
O(11)-Si(1)-C(18)-C(17) -112.60(19)
O(12)-Si(1)-C(18)-C(17) 127.50(19)
N(1)-Si(1)-C(18)-C(17) -97(26)
O(13)-Si(1)-C(18)-C(19) -172.50(17)
O(11)-Si(1)-C(18)-C(19) 66.81(18)
O(12)-Si(1)-C(18)-C(19) -53.09(18)
N(1)-Si(1)-C(18)-C(19) 83(26)
C(17)-C(18)-C(19)-C(20) -178.5(3)
Si(1)-C(18)-C(19)-C(20) 2.1(4)
O(22)-Si(2)-O(21)-C(21) 67.8(2)
O(23)-Si(2)-O(21)-C(21) -89.1(2)
C(28)-Si(2)-O(21)-C(21) 168.68(19)
N(2)-Si(2)-O(21)-C(21) -10.23(18)
O(23)-Si(2)-O(22)-C(23) 71.5(2)
O(21)-Si(2)-O(22)-C(23) -85.4(2)
C(28)-Si(2)-O(22)-C(23) 174.53(19)
N(2)-Si(2)-O(22)-C(23) -7.38(18)
O(22)-Si(2)-O(23)-C(25) -86.7(2)
O(21)-Si(2)-O(23)-C(25) 70.4(2)
C(28)-Si(2)-O(23)-C(25) 171.07(19)
N(2)-Si(2)-O(23)-C(25) -8.10(19)
O(22)-Si(2)-N(2)-C(22') -98.8(12)
O(23)-Si(2)-N(2)-C(22') 141.8(12)
O(21)-Si(2)-N(2)-C(22') 22.3(12)
C(28)-Si(2)-N(2)-C(22') -13(3)
O(22)-Si(2)-N(2)-C(26) 103.64(15)
O(23)-Si(2)-N(2)-C(26) -15.80(15)
O(21)-Si(2)-N(2)-C(26) -135.33(15)
C(28)-Si(2)-N(2)-C(26) -170(3)
O(22)-Si(2)-N(2)-C(24') 29.8(8)
209
O(23)-Si(2)-N(2)-C(24') -89.7(7)
O(21)-Si(2)-N(2)-C(24') 150.8(7)
C(28)-Si(2)-N(2)-C(24') 116(3)
O(22)-Si(2)-N(2)-C(22) -134.97(17)
O(23)-Si(2)-N(2)-C(22) 105.59(17)
O(21)-Si(2)-N(2)-C(22) -13.94(16)
C(28)-Si(2)-N(2)-C(22) -49(3)
O(22)-Si(2)-N(2)-C(24) -16.69(15)
O(23)-Si(2)-N(2)-C(24) -136.13(15)
O(21)-Si(2)-N(2)-C(24) 104.34(15)
C(28)-Si(2)-N(2)-C(24) 69(3)
O(22)-Si(2)-N(2)-C(26') 139.9(8)
O(23)-Si(2)-N(2)-C(26') 20.5(8)
O(21)-Si(2)-N(2)-C(26') -99.0(8)
C(28)-Si(2)-N(2)-C(26') -134(3)
Si(2)-O(21)-C(21)-C(22) 32.0(3)
Si(2)-O(21)-C(21)-C(22') -2.3(11)
C(22')-N(2)-C(22)-C(21) -64.8(17)
C(26)-N(2)-C(22)-C(21) 146.2(2)
C(24')-N(2)-C(22)-C(21) -120.1(14)
C(24)-N(2)-C(22)-C(21) -82.3(2)
C(26')-N(2)-C(22)-C(21) 130.2(8)
Si(2)-N(2)-C(22)-C(21) 31.1(2)
O(21)-C(21)-C(22)-N(2) -39.6(3)
C(22')-C(21)-C(22)-N(2) 56.7(16)
Si(2)-O(22)-C(23)-C(24) 29.8(3)
Si(2)-O(22)-C(23)-C(24') -16.0(8)
C(22')-N(2)-C(24)-C(23) 136.8(10)
C(26)-N(2)-C(24)-C(23) -81.3(2)
C(24')-N(2)-C(24)-C(23) -60.6(10)
C(22)-N(2)-C(24)-C(23) 146.86(19)
C(26')-N(2)-C(24)-C(23) -103.4(13)
Si(2)-N(2)-C(24)-C(23) 33.2(2)
O(22)-C(23)-C(24)-N(2) -40.0(3)
C(24')-C(23)-C(24)-N(2) 58.2(10)
Si(2)-O(23)-C(25)-C(26') -10.7(11)
210
Si(2)-O(23)-C(25)-C(26) 29.7(3)
C(22')-N(2)-C(26)-C(25) -111.6(18)
C(24')-N(2)-C(26)-C(25) 131.1(8)
C(22)-N(2)-C(26)-C(25) -83.1(2)
C(24)-N(2)-C(26)-C(25) 146.4(2)
C(26')-N(2)-C(26)-C(25) -55.0(12)
Si(2)-N(2)-C(26)-C(25) 32.0(2)
C(26')-C(25)-C(26)-N(2) 68.6(14)
O(23)-C(25)-C(26)-N(2) -39.5(3)
C(26)-N(2)-C(22')-C(21) 115.9(14)
C(24')-N(2)-C(22')-C(21) -144.4(14)
C(22)-N(2)-C(22')-C(21) 66.5(17)
C(24)-N(2)-C(22')-C(21) -130.0(17)
C(26')-N(2)-C(22')-C(21) 83.2(19)
Si(2)-N(2)-C(22')-C(21) -27.6(19)
O(21)-C(21)-C(22')-N(2) 22(2)
C(22)-C(21)-C(22')-N(2) -72.8(18)
C(22')-N(2)-C(24')-C(23) 77.2(16)
C(26)-N(2)-C(24')-C(23) -142.9(11)
C(22)-N(2)-C(24')-C(23) 110.5(12)
C(24)-N(2)-C(24')-C(23) 57.1(8)
C(26')-N(2)-C(24')-C(23) -146.6(10)
Si(2)-N(2)-C(24')-C(23) -41.0(10)
O(22)-C(23)-C(24')-N(2) 39.4(11)
C(24)-C(23)-C(24')-N(2) -58.2(8)
O(23)-C(25)-C(26')-N(2) 28.8(16)
C(26)-C(25)-C(26')-N(2) -59.3(11)
C(22')-N(2)-C(26')-C(25) -143.7(15)
C(26)-N(2)-C(26')-C(25) 71.3(14)
C(24')-N(2)-C(26')-C(25) 77.4(15)
C(22)-N(2)-C(26')-C(25) -134.2(13)
C(24)-N(2)-C(26')-C(25) 107.4(13)
Si(2)-N(2)-C(26')-C(25) -30.0(14)
O(22)-Si(2)-C(28)-C(27) -122.3(2)
O(23)-Si(2)-C(28)-C(27) -2.5(2)
O(21)-Si(2)-C(28)-C(27) 117.1(2)
211
N(2)-Si(2)-C(28)-C(27) 152(3)
O(22)-Si(2)-C(28)-C(29) 60.68(18)
O(23)-Si(2)-C(28)-C(29) -179.55(17)
O(21)-Si(2)-C(28)-C(29) -60.01(18)
N(2)-Si(2)-C(28)-C(29) -25(3)
C(27)-C(28)-C(29)-C(30) 170.3(3)
Si(2)-C(28)-C(29)-C(30) -12.5(4)
O(32)-Si(3)-O(31)-C(31) 87.7(3)
O(33)-Si(3)-O(31)-C(31) -69.8(3)
C(38)-Si(3)-O(31)-C(31) -171.2(3)
N(3)-Si(3)-O(31)-C(31) 8.6(3)
O(31)-Si(3)-O(32)-C(33) -71.6(2)
O(33)-Si(3)-O(32)-C(33) 86.2(2)
C(38)-Si(3)-O(32)-C(33) -174.4(2)
N(3)-Si(3)-O(32)-C(33) 7.5(2)
O(32)-Si(3)-O(33)-C(35) -72.4(2)
O(31)-Si(3)-O(33)-C(35) 85.1(2)
C(38)-Si(3)-O(33)-C(35) -171.87(19)
N(3)-Si(3)-O(33)-C(35) 6.49(18)
O(32)-Si(3)-N(3)-C(32) -103.66(19)
O(31)-Si(3)-N(3)-C(32) 16.09(19)
O(33)-Si(3)-N(3)-C(32) 136.82(19)
C(38)-Si(3)-N(3)-C(32) -169(3)
O(32)-Si(3)-N(3)-C(34) 16.24(17)
O(31)-Si(3)-N(3)-C(34) 135.99(18)
O(33)-Si(3)-N(3)-C(34) -103.28(17)
C(38)-Si(3)-N(3)-C(34) -49(3)
O(32)-Si(3)-N(3)-C(36) 136.28(15)
O(31)-Si(3)-N(3)-C(36) -103.97(16)
O(33)-Si(3)-N(3)-C(36) 16.76(14)
C(38)-Si(3)-N(3)-C(36) 71(3)
Si(3)-O(31)-C(31)-C(32) -31.1(4)
C(34)-N(3)-C(32)-C(31) -147.1(2)
C(36)-N(3)-C(32)-C(31) 81.0(3)
Si(3)-N(3)-C(32)-C(31) -33.2(3)
O(31)-C(31)-C(32)-N(3) 41.0(3)
212
Si(3)-O(32)-C(33)-C(34) -29.4(4)
C(32)-N(3)-C(34)-C(33) 81.1(3)
C(36)-N(3)-C(34)-C(33) -146.9(2)
Si(3)-N(3)-C(34)-C(33) -32.7(3)
O(32)-C(33)-C(34)-N(3) 39.6(3)
Si(3)-O(33)-C(35)-C(36) -28.1(3)
C(32)-N(3)-C(36)-C(35) -146.7(2)
C(34)-N(3)-C(36)-C(35) 81.4(2)
Si(3)-N(3)-C(36)-C(35) -32.8(2)
O(33)-C(35)-C(36)-N(3) 38.9(2)
O(32)-Si(3)-C(38)-C(37) 125.9(2)
O(31)-Si(3)-C(38)-C(37) 6.0(2)
O(33)-Si(3)-C(38)-C(37) -114.9(2)
N(3)-Si(3)-C(38)-C(37) -169(3)
O(32)-Si(3)-C(38)-C(39) -53.42(19)
O(31)-Si(3)-C(38)-C(39) -173.39(19)
O(33)-Si(3)-C(38)-C(39) 65.73(19)
N(3)-Si(3)-C(38)-C(39) 11(3)
C(37)-C(38)-C(39)-C(40) 36.3(4)
Si(3)-C(38)-C(39)-C(40) -144.3(3)
213
Unit cell of 13.1.2a not showing Head-to-Tail packing (Among 3 molecules per
asymmetric unit shows 2 are in S-trans and 1 in S-cis conformation)
214
Appendix E
Crystallographic Data for 13.1.2c
215
Table 1. Crystal data and structure refinement for C16H13O4SiK(THF)2
Empirical formula C24 H29 K O6 Si
Formula weight 480.66
Temperature 193(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic
Space group P2(1)/c - C 52h
(No. 14)
Unit cell dimensions a = 12.445(2) Å
b = 15.623(3) Å, β = 108.108(3)°
c = 13.259(2) Å
Volume 2450.3(7) Å3
Z 4
Density (calculated) 1.303 g/cm3
Absorption coefficient 0.302 mm-1
F(000) 1016
Crystal size 0.36 x 0.05 x 0.02 mm3
Theta range for data collection 4.09 to 24.15°
Index ranges -14≤h≤14, -17≤k≤17, -15≤l≤15
Reflections collected 16300
Independent reflections 3879 [R(int) = 0.0950]
Completeness to theta = 24.15° 99.3 %
Absorption correction Multi-scan (SADABS)
Refinement method Full-matrix least-squares on F2
Data / parameters 3879 / 341
Goodness-of-fit on F2 1.047
Final R indices [I>2sigma(I)] R1 = 0.0709, wR2 = 0.1337
R indices (all data) R1 = 0.1187, wR2 = 0.1525
Largest diff. peak and hole 0.245 and -0.222 e-/Å3
216
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters (Å2x 103) for
C16H13O4SiK(THF)2. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
K(1) 6571(1) 1547(1) 7415(1) 42(1)
Si(1) 6830(1) 1994(1) 10238(1) 39(1)
O(1) 7752(2) 2062(2) 9453(2) 45(1)
O(2) 7649(2) 2754(2) 11062(2) 43(1)
O(3) 5816(3) 2254(2) 10879(2) 53(1)
O(4) 5757(2) 1988(2) 9054(2) 44(1)
C(1) 8656(4) 2578(3) 9899(3) 39(1)
C(2) 8596(4) 2984(3) 10805(3) 44(1)
C(3) 9403(4) 3552(3) 11348(4) 58(1)
C(4) 10290(4) 3726(3) 10949(5) 64(2)
C(5) 10359(4) 3329(3) 10054(4) 59(1)
C(6) 9535(4) 2744(3) 9511(4) 55(1)
C(7) 4707(4) 2010(3) 9176(4) 45(1)
C(8) 4750(4) 2161(3) 10217(4) 51(1)
C(9) 3760(5) 2206(3) 10488(5) 69(2)
C(10) 2740(5) 2114(3) 9684(6) 72(2)
C(11) 2703(4) 1965(3) 8654(5) 67(2)
C(12) 3698(4) 1914(3) 8387(4) 59(1)
C(13) 7089(4) 842(3) 10677(3) 46(1)
C(14) 6423(5) 244(3) 10072(4) 71(2)
C(15) 7932(5) 529(4) 11594(5) 88(2)
C(16) 8620(7) 979(5) 12300(6) 148(4)
O(5) 4788(3) 457(3) 6673(3) 80(1)
C(17) 4680(30) -176(18) 7280(20) 99(10)
C(18) 4120(50) -900(30) 6390(40) 103(11)
C(19) 3530(30) -450(30) 5569(19) 180(20)
C(20) 3780(30) 596(19) 5800(30) 116(11)
C(17') 4700(20) -420(20) 7170(20) 109(13)
C(18') 3850(50) -840(40) 6620(50) 127(16)
C(19') 3270(30) -300(20) 5640(30) 180(17)
C(20') 3940(30) 330(17) 5750(20) 105(12)
217
O(6) 7892(3) 136(2) 7709(3) 70(1)
C(21) 8811(7) 154(4) 8668(5) 65(2)
C(22) 8986(8) -744(4) 9057(6) 84(2)
C(23) 8457(9) -1284(5) 8086(6) 103(3)
C(24) 7944(9) -633(6) 7179(6) 81(3)
C(21') 8350(30) -140(30) 8790(30) 51(11)
C(22') 9400(30) -640(30) 8620(30) 66(13)
C(23') 8800(40) -1040(30) 7500(40) 69(11)
C(24') 7580(50) -810(40) 7490(50) 90(20)
______________________________________________________________________________
218
Table 3. Bond lengths [Å] and angles [°] for C16H13O4SiK(THF)2
_____________________________________________________
K(1)-O(6) 2.705(3)
K(1)-O(3)#1 2.710(3)
K(1)-O(5) 2.726(4)
K(1)-O(4) 2.756(3)
K(1)-O(1) 2.764(3)
K(1)-O(2)#1 2.776(3)
Si(1)-O(4) 1.716(3)
Si(1)-O(2) 1.717(3)
Si(1)-O(3) 1.775(3)
Si(1)-O(1) 1.776(3)
Si(1)-C(13) 1.889(5)
O(1)-C(1) 1.361(5)
O(2)-C(2) 1.373(5)
O(3)-C(8) 1.351(5)
O(4)-C(7) 1.366(5)
C(1)-C(6) 1.371(6)
C(1)-C(2) 1.381(6)
C(2)-C(3) 1.365(6)
C(3)-C(4) 1.391(6)
C(4)-C(5) 1.365(7)
C(5)-C(6) 1.395(6)
C(7)-C(12) 1.370(6)
C(7)-C(8) 1.386(6)
C(8)-C(9) 1.388(6)
C(9)-C(10) 1.389(7)
C(10)-C(11) 1.371(7)
C(11)-C(12) 1.392(7)
C(13)-C(14) 1.337(6)
C(13)-C(15) 1.423(7)
C(15)-C(16) 1.267(8)
O(5)-C(17) 1.31(3)
O(5)-C(20) 1.43(4)
O(5)-C(17') 1.53(3)
O(5)-C(20') 1.36(3)
C(17)-C(18) 1.63(5)
C(18)-C(19) 1.31(6)
C(19)-C(20) 1.68(5)
C(17')-C(18') 1.27(6)
C(18')-C(19') 1.53(7)
C(19')-C(20') 1.27(4)
O(6)-C(21) 1.422(7)
O(6)-C(24) 1.405(8)
O(6)-C(21') 1.44(4)
O(6)-C(24') 1.53(6)
C(21)-C(22) 1.487(9) C(22)-C(23) 1.509(9)
219
C(23)-C(24) 1.553(11)
C(21')-C(22') 1.60(6)
C(22')-C(23') 1.57(6)
C(23')-C(24') 1.55(7)
O(6)-K(1)-O(3)#1 136.46(10)
O(6)-K(1)-O(5) 86.16(13)
O(3)#1-K(1)-O(5) 96.17(12)
O(6)-K(1)-O(4) 116.47(10)
O(3)#1-K(1)-O(4) 107.05(9)
O(5)-K(1)-O(4) 89.05(11)
O(6)-K(1)-O(1) 88.93(10)
O(3)#1-K(1)-O(1) 119.21(10)
O(5)-K(1)-O(1) 131.30(11)
O(4)-K(1)-O(1) 50.95(8)
O(6)-K(1)-O(2)#1 91.13(10)
O(3)#1-K(1)-O(2)#1 50.74(8)
O(5)-K(1)-O(2)#1 121.02(11)
O(4)-K(1)-O(2)#1 141.37(9)
O(1)-K(1)-O(2)#1 107.48(9)
O(4)-Si(1)-O(2) 136.48(15)
O(4)-Si(1)-O(3) 88.43(15)
O(2)-Si(1)-O(3) 84.65(14)
O(4)-Si(1)-O(1) 85.69(14)
O(2)-Si(1)-O(1) 88.17(14)
O(3)-Si(1)-O(1) 162.32(16)
O(4)-Si(1)-C(13) 106.63(18)
O(2)-Si(1)-C(13) 116.88(18)
O(3)-Si(1)-C(13) 98.56(17)
O(1)-Si(1)-C(13) 99.10(17)
C(1)-O(1)-Si(1) 112.2(2)
C(1)-O(1)-K(1) 135.6(2)
Si(1)-O(1)-K(1) 108.17(13)
C(2)-O(2)-Si(1) 114.2(3)
C(2)-O(2)-K(1)#2 133.0(2)
Si(1)-O(2)-K(1)#2 111.87(13)
C(8)-O(3)-Si(1) 111.4(3)
C(8)-O(3)-K(1)#2 127.1(2)
Si(1)-O(3)-K(1)#2 112.71(14)
C(7)-O(4)-Si(1) 113.2(3)
C(7)-O(4)-K(1) 134.3(3)
Si(1)-O(4)-K(1) 110.54(13)
O(1)-C(1)-C(6) 126.7(4)
O(1)-C(1)-C(2) 112.9(4)
C(6)-C(1)-C(2) 120.3(4)
C(3)-C(2)-O(2) 126.0(4)
C(3)-C(2)-C(1) 121.8(4)
O(2)-C(2)-C(1) 112.2(4)
C(2)-C(3)-C(4) 117.9(5)
C(5)-C(4)-C(3) 120.9(5)
C(4)-C(5)-C(6) 120.8(5)
C(1)-C(6)-C(5) 118.3(5)
O(4)-C(7)-C(12) 126.2(4)
O(4)-C(7)-C(8) 112.3(4)
C(12)-C(7)-C(8) 121.5(5)
O(3)-C(8)-C(7) 113.1(4)
O(3)-C(8)-C(9) 126.7(5)
C(7)-C(8)-C(9) 120.2(5)
C(8)-C(9)-C(10) 118.0(5)
C(11)-C(10)-C(9) 121.4(5)
C(10)-C(11)-C(12) 120.4(5)
C(7)-C(12)-C(11) 118.4(5)
220
C(14)-C(13)-C(15) 115.3(5)
C(14)-C(13)-Si(1) 117.8(4)
C(15)-C(13)-Si(1) 126.9(4)
C(16)-C(15)-C(13) 126.2(7)
C(17)-O(5)-C(20') 104.3(19)
C(17)-O(5)-C(20) 113(2)
C(20')-O(5)-C(17') 96.8(16)
C(20)-O(5)-C(17') 108.9(17)
C(17)-O(5)-K(1) 118.3(14)
C(20')-O(5)-K(1) 137.2(14)
C(20)-O(5)-K(1) 127.2(15)
C(17')-O(5)-K(1) 123.9(10)
O(5)-C(17)-C(18) 100(2)
C(19)-C(18)-C(17) 104(3)
C(18)-C(19)-C(20) 110(3)
O(5)-C(20)-C(19) 94(2)
C(18')-C(17')-O(5) 112(3)
C(17')-C(18')-C(19') 107(4)
C(20')-C(19')-C(18') 102(3)
C(19')-C(20')-O(5) 121(3)
C(24)-O(6)-C(21) 108.3(5)
C(24)-O(6)-C(21') 100.3(18)
C(21)-O(6)-C(24') 106(3)
C(21')-O(6)-C(24') 84(3)
C(24)-O(6)-K(1) 138.3(4)
C(21)-O(6)-K(1) 113.4(3)
C(21')-O(6)-K(1) 114.9(17)
C(24')-O(6)-K(1) 131(2)
O(6)-C(21)-C(22) 106.4(6)
C(21)-C(22)-C(23) 104.7(6)
C(22)-C(23)-C(24) 105.1(6)
O(6)-C(24)-C(23) 104.1(6)
O(6)-C(21')-C(22') 95(3)
C(23')-C(22')-C(21') 99(3)
C(24')-C(23')-C(22') 95(3)
O(6)-C(24')-C(23') 93(3)
221
Table 4. Anisotropic displacement parameters (Å2x 103) for C16H13O4SiK(THF)2. The anisotropic
displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]
______________________________________________________________________________
U11 U22 U33 U23 U13 U12
______________________________________________________________________________
K(1) 47(1) 45(1) 36(1) 5(1) 15(1) 0(1)
Si(1) 42(1) 39(1) 41(1) -6(1) 20(1) -3(1)
O(1) 47(2) 49(2) 45(2) -7(1) 23(2) -6(2)
O(2) 38(2) 49(2) 46(2) -12(1) 19(1) -6(1)
O(3) 45(2) 61(2) 64(2) -31(2) 30(2) -16(2)
O(4) 43(2) 46(2) 46(2) 4(1) 19(2) -3(2)
C(1) 41(3) 31(2) 46(3) 8(2) 16(2) 5(2)
C(2) 37(3) 42(3) 54(3) -4(2) 16(2) 5(2)
C(3) 41(3) 58(3) 73(3) -17(3) 17(3) -9(3)
C(4) 44(3) 60(4) 89(4) -11(3) 20(3) -13(3)
C(5) 42(3) 48(3) 93(4) 12(3) 32(3) 2(3)
C(6) 50(3) 54(3) 70(3) -1(3) 32(3) 1(3)
C(7) 43(3) 34(3) 57(3) 7(2) 13(3) -1(2)
C(8) 45(3) 35(3) 78(4) -17(2) 26(3) -5(2)
C(9) 62(4) 56(3) 104(4) -33(3) 48(4) -14(3)
C(10) 43(3) 46(3) 132(6) -2(3) 37(4) 4(3)
C(11) 41(3) 50(3) 100(5) 26(3) 8(3) 1(3)
C(12) 59(4) 55(3) 62(3) 25(3) 15(3) -1(3)
C(13) 38(3) 64(3) 39(3) 10(2) 14(2) 3(3)
C(14) 78(4) 44(3) 82(4) 7(3) 13(3) -2(3)
C(15) 91(5) 76(4) 85(5) 3(4) 8(4) -10(4)
C(16) 181(9) 105(6) 99(6) -1(5) -43(6) -22(6)
O(5) 81(3) 72(3) 74(3) -1(2) 6(2) -28(2)
C(17) 200(30) 38(11) 78(14) -21(10) 72(15) -40(11)
C(18) 170(40) 55(12) 100(20) -40(14) 70(20) -39(16)
C(19) 270(40) 140(30) 53(13) -31(16) -58(17) -80(20)
C(20) 84(14) 44(19) 170(20) -26(13) -27(12) 13(13)
C(17') 92(17) 100(30) 110(20) 70(20) -11(13) -5(14)
C(18') 170(30) 110(30) 140(30) -50(20) 100(20) -70(20)
C(19') 129(19) 83(17) 260(40) 73(19) -35(19) -52(15)
C(20') 170(30) 24(14) 73(12) -6(9) -28(14) -15(14)
O(6) 75(3) 66(3) 57(2) -3(2) 1(2) 21(2)
222
C(21) 69(5) 60(5) 66(5) -4(4) 19(4) 7(4)
C(22) 119(7) 52(5) 59(5) 4(4) -4(5) -13(5)
C(23) 132(7) 57(5) 85(6) 10(4) -20(6) -5(5)
C(24) 81(7) 84(6) 63(5) -24(5) 2(5) 7(5)
______________________________________________________________________________
223
Table 5. Hydrogen coordinates (x 104) and isotropic displacement parameters (Å2x 10 3)
for C16H13O4SiK(THF)2
________________________________________________________________________
x y z U(eq)
________________________________________________________________________
H(3) 9359 3820 11977 70
H(4) 10855 4127 11304 77
H(5) 10976 3452 9799 70
H(6) 9582 2467 8888 66
H(9) 3780 2296 11202 82
H(10) 2052 2155 9850 86
H(11) 1995 1896 8121 80
H(12) 3677 1816 7674 71
H(14A) 6532 -342 10267 85
H(14B) 5841 406 9447 85
H(15) 7985 -74 11685 106
H(16A) 8600 1586 12243 178
H(16B) 9155 710 12886 178
H(17A) 4179 -25 7705 119
H(17B) 5426 -362 7767 119
H(18A) 4712 -1237 6213 123
H(18B) 3631 -1292 6634 123
H(19A) 2714 -568 5434 217
H(19B) 3730 -627 4932 217
H(20A) 3935 895 5195 139
H(20B) 3182 893 6001 139
H(17C) 5398 -748 7238 130
H(17D) 4646 -328 7893 130
H(18C) 3327 -946 7036 152
H(18D) 4094 -1395 6411 152
H(19C) 3204 -622 4977 216
H(19D) 2505 -116 5634 216
H(20C) 3469 855 5616 127
H(20D) 4291 292 5179 127
H(21A) 8632 526 9198 78
H(21B) 9501 375 8535 78
224
H(22A) 8612 -846 9605 101
H(22B) 9802 -873 9362 101
H(23A) 7860 -1658 8196 124
H(23B) 9033 -1646 7921 124
H(24A) 8434 -572 6720 97
H(24B) 7181 -816 6737 97
H(21C) 7828 -527 9013 62
H(21D) 8577 342 9298 62
H(22C) 10011 -237 8595 79
H(22D) 9707 -1076 9168 79
H(23C) 9014 -766 6921 83
H(23D) 8916 -1671 7488 83
H(24C) 7009 -906 6788 102
H(24D) 7358 -1090 8057 102
________________________________________________________________________
225
Table 6. Torsion angles [°] for C16H13O4SiK(THF)2
________________________________________________________________
O(4)-Si(1)-O(1)-C(1) 142.5(3)
O(2)-Si(1)-O(1)-C(1) 5.6(3)
O(3)-Si(1)-O(1)-C(1) 71.6(6)
C(13)-Si(1)-O(1)-C(1) -111.3(3)
O(4)-Si(1)-O(1)-K(1) -18.47(13)
O(2)-Si(1)-O(1)-K(1) -155.35(14)
O(3)-Si(1)-O(1)-K(1) -89.4(5)
C(13)-Si(1)-O(1)-K(1) 87.71(18)
O(6)-K(1)-O(1)-C(1) 94.1(3)
O(3)#1-K(1)-O(1)-C(1) -51.0(4)
O(5)-K(1)-O(1)-C(1) 178.0(3)
O(4)-K(1)-O(1)-C(1) -139.8(4)
O(2)#1-K(1)-O(1)-C(1) 3.2(4)
O(6)-K(1)-O(1)-Si(1) -111.43(15)
O(3)#1-K(1)-O(1)-Si(1) 103.46(14)
O(5)-K(1)-O(1)-Si(1) -27.5(2)
O(4)-K(1)-O(1)-Si(1) 14.67(11)
O(2)#1-K(1)-O(1)-Si(1) 157.72(13)
O(4)-Si(1)-O(2)-C(2) -86.5(3)
O(3)-Si(1)-O(2)-C(2) -168.6(3)
O(1)-Si(1)-O(2)-C(2) -4.8(3)
C(13)-Si(1)-O(2)-C(2) 94.5(3)
O(4)-Si(1)-O(2)-K(1)#2 83.6(2)
O(3)-Si(1)-O(2)-K(1)#2 1.51(15)
O(1)-Si(1)-O(2)-K(1)#2 165.34(14)
C(13)-Si(1)-O(2)-K(1)#2 -95.39(19)
O(4)-Si(1)-O(3)-C(8) 11.5(3)
O(2)-Si(1)-O(3)-C(8) 148.4(3)
O(1)-Si(1)-O(3)-C(8) 82.0(6)
C(13)-Si(1)-O(3)-C(8) -95.1(3)
O(4)-Si(1)-O(3)-K(1)#2 -138.54(16)
O(2)-Si(1)-O(3)-K(1)#2 -1.56(16)
O(1)-Si(1)-O(3)-K(1)#2 -68.0(6)
C(13)-Si(1)-O(3)-K(1)#2 114.87(19)
O(2)-Si(1)-O(4)-C(7) -92.1(3)
226
O(3)-Si(1)-O(4)-C(7) -11.5(3)
O(1)-Si(1)-O(4)-C(7) -174.9(3)
C(13)-Si(1)-O(4)-C(7) 86.9(3)
O(2)-Si(1)-O(4)-K(1) 101.6(2)
O(3)-Si(1)-O(4)-K(1) -177.88(14)
O(1)-Si(1)-O(4)-K(1) 18.81(13)
C(13)-Si(1)-O(4)-K(1) -79.41(18)
O(6)-K(1)-O(4)-C(7) -113.3(3)
O(3)#1-K(1)-O(4)-C(7) 68.1(3)
O(5)-K(1)-O(4)-C(7) -28.0(3)
O(1)-K(1)-O(4)-C(7) -177.7(4)
O(2)#1-K(1)-O(4)-C(7) 115.6(3)
O(6)-K(1)-O(4)-Si(1) 49.06(17)
O(3)#1-K(1)-O(4)-Si(1) -129.54(14)
O(5)-K(1)-O(4)-Si(1) 134.29(16)
O(1)-K(1)-O(4)-Si(1) -15.42(11)
O(2)#1-K(1)-O(4)-Si(1) -82.12(19)
Si(1)-O(1)-C(1)-C(6) 177.9(4)
K(1)-O(1)-C(1)-C(6) -28.3(6)
Si(1)-O(1)-C(1)-C(2) -5.2(4)
K(1)-O(1)-C(1)-C(2) 148.5(3)
Si(1)-O(2)-C(2)-C(3) -177.9(4)
K(1)#2-O(2)-C(2)-C(3) 14.7(6)
Si(1)-O(2)-C(2)-C(1) 2.8(4)
K(1)#2-O(2)-C(2)-C(1) -164.5(2)
O(1)-C(1)-C(2)-C(3) -177.6(4)
C(6)-C(1)-C(2)-C(3) -0.6(7)
O(1)-C(1)-C(2)-O(2) 1.6(5)
C(6)-C(1)-C(2)-O(2) 178.7(4)
O(2)-C(2)-C(3)-C(4) -178.1(4)
C(1)-C(2)-C(3)-C(4) 1.1(7)
C(2)-C(3)-C(4)-C(5) -1.1(8)
C(3)-C(4)-C(5)-C(6) 0.6(8)
O(1)-C(1)-C(6)-C(5) 176.7(4)
C(2)-C(1)-C(6)-C(5) 0.0(6)
C(4)-C(5)-C(6)-C(1) -0.1(7)
Si(1)-O(4)-C(7)-C(12) -172.1(4)
227
K(1)-O(4)-C(7)-C(12) -10.1(6)
Si(1)-O(4)-C(7)-C(8) 9.1(4)
K(1)-O(4)-C(7)-C(8) 171.0(3)
Si(1)-O(3)-C(8)-C(7) -8.8(5)
K(1)#2-O(3)-C(8)-C(7) 135.9(3)
Si(1)-O(3)-C(8)-C(9) 171.4(4)
K(1)#2-O(3)-C(8)-C(9) -44.0(6)
O(4)-C(7)-C(8)-O(3) 0.1(5)
C(12)-C(7)-C(8)-O(3) -178.8(4)
O(4)-C(7)-C(8)-C(9) 179.9(4)
C(12)-C(7)-C(8)-C(9) 1.1(7)
O(3)-C(8)-C(9)-C(10) 178.4(4)
C(7)-C(8)-C(9)-C(10) -1.5(7)
C(8)-C(9)-C(10)-C(11) 1.4(8)
C(9)-C(10)-C(11)-C(12) -1.0(8)
O(4)-C(7)-C(12)-C(11) -179.3(4)
C(8)-C(7)-C(12)-C(11) -0.5(7)
C(10)-C(11)-C(12)-C(7) 0.5(7)
O(4)-Si(1)-C(13)-C(14) -2.4(4)
O(2)-Si(1)-C(13)-C(14) 176.9(4)
O(3)-Si(1)-C(13)-C(14) 88.5(4)
O(1)-Si(1)-C(13)-C(14) -90.6(4)
O(4)-Si(1)-C(13)-C(15) 177.2(5)
O(2)-Si(1)-C(13)-C(15) -3.5(5)
O(3)-Si(1)-C(13)-C(15) -91.8(5)
O(1)-Si(1)-C(13)-C(15) 89.0(5)
C(14)-C(13)-C(15)-C(16) -176.7(8)
Si(1)-C(13)-C(15)-C(16) 3.7(11)
O(6)-K(1)-O(5)-C(17) 55.3(14)
O(3)#1-K(1)-O(5)-C(17) -168.4(14)
O(4)-K(1)-O(5)-C(17) -61.3(14)
O(1)-K(1)-O(5)-C(17) -29.9(14)
O(2)#1-K(1)-O(5)-C(17) 144.3(14)
O(6)-K(1)-O(5)-C(20') -119(2)
O(3)#1-K(1)-O(5)-C(20') 17(2)
O(4)-K(1)-O(5)-C(20') 124(2)
O(1)-K(1)-O(5)-C(20') 156(2)
228
O(2)#1-K(1)-O(5)-C(20') -30(2)
O(6)-K(1)-O(5)-C(20) -140.9(19)
O(3)#1-K(1)-O(5)-C(20) -4.6(19)
O(4)-K(1)-O(5)-C(20) 102.5(19)
O(1)-K(1)-O(5)-C(20) 133.9(19)
O(2)#1-K(1)-O(5)-C(20) -51.9(19)
O(6)-K(1)-O(5)-C(17') 40.5(15)
O(3)#1-K(1)-O(5)-C(17') 176.9(15)
O(4)-K(1)-O(5)-C(17') -76.1(15)
O(1)-K(1)-O(5)-C(17') -44.6(15)
O(2)#1-K(1)-O(5)-C(17') 129.6(15)
C(20')-O(5)-C(17)-C(18) 29(3)
C(20)-O(5)-C(17)-C(18) 47(3)
C(17')-O(5)-C(17)-C(18) -30(8)
K(1)-O(5)-C(17)-C(18) -147(2)
O(5)-C(17)-C(18)-C(19) -31(4)
C(17)-C(18)-C(19)-C(20) 7(4)
C(17)-O(5)-C(20)-C(19) -40(3)
C(20')-O(5)-C(20)-C(19) 26(8)
C(17')-O(5)-C(20)-C(19) -26(3)
K(1)-O(5)-C(20)-C(19) 155.2(15)
C(18)-C(19)-C(20)-O(5) 16(4)
C(17)-O(5)-C(17')-C(18') 117(10)
C(20')-O(5)-C(17')-C(18') -7(3)
C(20)-O(5)-C(17')-C(18') 8(4)
K(1)-O(5)-C(17')-C(18') -173(2)
O(5)-C(17')-C(18')-C(19') 2(4)
C(17')-C(18')-C(19')-C(20') 4(5)
C(18')-C(19')-C(20')-O(5) -11(5)
C(17)-O(5)-C(20')-C(19') 0(4)
C(20)-O(5)-C(20')-C(19') -119(12)
C(17')-O(5)-C(20')-C(19') 11(4)
K(1)-O(5)-C(20')-C(19') 174(3)
O(3)#1-K(1)-O(6)-C(24) -54.5(9)
O(5)-K(1)-O(6)-C(24) 40.4(8)
O(4)-K(1)-O(6)-C(24) 127.4(8)
O(1)-K(1)-O(6)-C(24) 172.0(8)
229
O(2)#1-K(1)-O(6)-C(24) -80.6(8)
O(3)#1-K(1)-O(6)-C(21) 125.2(4)
O(5)-K(1)-O(6)-C(21) -139.8(4)
O(4)-K(1)-O(6)-C(21) -52.8(5)
O(1)-K(1)-O(6)-C(21) -8.3(4)
O(2)#1-K(1)-O(6)-C(21) 99.1(4)
O(3)#1-K(1)-O(6)-C(21') 160.8(19)
O(5)-K(1)-O(6)-C(21') -104.3(19)
O(4)-K(1)-O(6)-C(21') -17.3(19)
O(1)-K(1)-O(6)-C(21') 27.2(19)
O(2)#1-K(1)-O(6)-C(21') 134.7(19)
O(3)#1-K(1)-O(6)-C(24') -94(3)
O(5)-K(1)-O(6)-C(24') 1(3)
O(4)-K(1)-O(6)-C(24') 88(3)
O(1)-K(1)-O(6)-C(24') 132(3)
O(2)#1-K(1)-O(6)-C(24') -120(3)
C(24)-O(6)-C(21)-C(22) -34.9(9)
C(21')-O(6)-C(21)-C(22) 45(3)
C(24')-O(6)-C(21)-C(22) -5(2)
K(1)-O(6)-C(21)-C(22) 145.3(6)
O(6)-C(21)-C(22)-C(23) 21.8(10)
C(21)-C(22)-C(23)-C(24) -2.6(13)
C(21)-O(6)-C(24)-C(23) 32.2(11)
C(21')-O(6)-C(24)-C(23) -0.2(19)
C(24')-O(6)-C(24)-C(23) -58(5)
K(1)-O(6)-C(24)-C(23) -148.1(6)
C(22)-C(23)-C(24)-O(6) -17.4(13)
C(24)-O(6)-C(21')-C(22') 47(3)
C(21)-O(6)-C(21')-C(22') -61(3)
C(24')-O(6)-C(21')-C(22') 71(3)
K(1)-O(6)-C(21')-C(22') -156(2)
C(24)-O(6)-C(21')-C(24') -24(2)
C(21)-O(6)-C(21')-C(24') -132(4)
K(1)-O(6)-C(21')-C(24') 133(2)
O(6)-C(21')-C(22')-C(23') -40(4)
C(24')-C(21')-C(22')-C(23') 8(4)
C(21')-C(22')-C(23')-C(24') -10(4)
230
C(24)-O(6)-C(24')-C(23') 43(3)
C(21)-O(6)-C(24')-C(23') -57(4)
C(21')-O(6)-C(24')-C(23') -81(4)
K(1)-O(6)-C(24')-C(23') 161(2)
C(22')-C(23')-C(24')-O(6) 53(4)
________________________________________________________________
Symmetry transformations used to generate equivalent atoms:
#1 x,-y+1/2,z-1/2 #2 x,-y+1/2,z+1/2
231
Unit cell of 13.1.2c showing Head-to-Tail packing
(only S-trans conformer noticed)
232
Appendix F
Crystallographic Data for 13.1.1d
233
Table 1. Crystal data and structure refinement for K[Si(O2C6H4)2(C14H12NO2)]-MeCN
Identification code a45n2m
Empirical formula C28 H23 K N2 O6 Si
Formula weight 550.67
Temperature 213(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic
Space group P2(1)/c– C 52h
(No. 14)
Unit cell dimensions a = 10.141(8) Å
b = 12.072(10) Å, β= 95.56(2)°
c = 21.290(14) Å
Volume 2594(3) Å3
Z 4
Density (calculated) 1.410 g/m3
Absorption coefficient 0.298 mm-1
F(000) 1144
Crystal size 0.38 x 0.04 x 0.02 mm3
Theta range for data collection 3.76 to 25.00°
Index ranges -12≤h≤12, -14≤k≤14, -25≤l≤25
Reflections collected 19509
Independent reflections 4548 [R(int) = 0.1063]
Completeness to theta = 25.00° 99.6 %
Absorption correction Multi-scan (SADABS)
Max. and min. transmission 0.7460 and 0.6088
Refinement method Full-matrix least-squares on F2
Data / parameters 4548 / 343
Goodness-of-fit on F2 1.085
Final R indices [3164 I>2σ(I) data] R1 = 0.0749, wR2 = 0.1407
R indices (all data) R1 = 0.1146, wR2 = 0.1570
Largest diff. peak and hole 0.348 and -0.409e-/Å3
------------------------------------------------------------------------------------------------------------------------
R1 = Σ ||Fo| - |Fc|| / Σ |Fo|
wR2 = { Σ [w(Fo2 - Fc
2)
2] / Σ [w(Fo
2)
2] }
1/2
234
Table 2. Atomic coordinates a,b ( x 104) and equivalent isotropic displacement parameters
(Å2x 103) for K[Si(O2C6H4)2(C14H12NO2)]-MeCN
_____________________________________________________________________________
x y z U(eq) c
_____________________________________________________________________________
K(1) 3332(1) 4862(1) 3083(1) 35(1)
Si(1) 4946(1) 7358(1) 2578(1) 25(1)
O(1) 3404(3) 6826(2) 2325(1) 28(1)
O(2) 4886(3) 8122(2) 1866(1) 31(1)
O(3) 4634(3) 6845(2) 3326(1) 28(1)
O(4) 5483(3) 8579(2) 2933(1) 31(1)
O(5) 10606(4) 5567(3) 3377(2) 57(1)
O(6) 8542(3) 8375(2) 2261(2) 40(1)
N(1) 9699(3) 7138(3) 2919(2) 30(1)
C(1) 2958(4) 7140(3) 1722(2) 26(1)
C(2) 3807(4) 7884(3) 1464(2) 27(1)
C(3) 3488(5) 8300(4) 872(2) 39(1)
C(4) 2328(5) 7964(4) 537(2) 49(1)
C(5) 1491(5) 7230(4) 795(2) 46(1)
C(6) 1798(4) 6804(4) 1398(2) 37(1)
C(7) 5114(4) 7534(4) 3796(2) 28(1)
C(8) 5563(4) 8527(3) 3575(2) 30(1)
C(9) 6015(4) 9351(4) 3985(2) 38(1)
C(10) 6029(5) 9160(4) 4626(3) 47(1)
C(11) 5596(5) 8167(4) 4844(2) 44(1)
C(12) 5115(4) 7335(4) 4433(2) 40(1)
C(13) 6316(4) 6372(3) 2436(2) 27(1)
C(14) 6784(4) 5613(3) 2856(2) 32(1)
C(15) 7877(4) 4831(4) 2719(2) 40(1)
C(16) 9022(4) 5458(3) 2441(2) 34(1)
C(17) 8498(4) 6407(3) 2004(2) 32(1)
C(18) 6997(4) 6384(4) 1838(2) 32(1)
C(19) 9884(5) 5997(4) 2963(2) 39(1)
C(20) 8877(4) 7439(4) 2386(2) 29(1)
C(21) 10188(4) 7906(3) 3400(2) 29(1)
C(22) 9279(4) 8548(4) 3681(2) 34(1)
235
C(23) 9740(5) 9311(4) 4135(2) 40(1)
C(24) 11073(5) 9415(4) 4307(2) 41(1)
C(25) 11978(5) 8755(4) 4033(2) 37(1)
C(26) 11528(4) 7993(3) 3572(2) 31(1)
N(2) 3103(7) 4523(5) 4405(3) 87(2)
C(27) 2434(8) 4254(6) 4759(4) 73(2)
C(28) 1573(8) 3876(8) 5233(4) 118(3)
______________________________________________________________________________ a The numbers in parentheses are the estimated standard deviations in the last significant digit. b Atoms are labeled in agreement with Figures 1 and 2. c U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
236
Table 3. Bond lengths [Å] and angles [°] for K[Si(O2C6H4)2(C14H12NO2)]-MeCN a,b
__________________________________________________________________________
K(1)-O(6)#1 2.665(3)
K(1)-O(3) 2.758(3)
K(1)-O(2)#1 2.766(3)
K(1)-O(1) 2.873(3)
K(1)-O(4)#1 3.004(3)
K(1)-O(5)#2 3.016(4)
K(1)-N(2) 2.876(6)
Si(1)-O(4) 1.721(3)
Si(1)-O(1) 1.727(3)
Si(1)-O(3) 1.766(3)
Si(1)-O(2) 1.770(3)
Si(1)-C(13) 1.876(4)
O(1)-C(1) 1.374(5)
O(2)-C(2) 1.353(5)
O(3)-C(7) 1.356(5)
O(4)-C(8) 1.364(5)
N(1)-C(20) 1.389(5)
N(1)-C(19) 1.392(6)
N(1)-C(21) 1.435(5)
O(5)-C(19) 1.207(5) O(6)-C(20) 1.203(5)
C(1)-C(6) 1.366(6)
C(1)-C(2) 1.393(6)
C(2)-C(3) 1.367(6)
C(3)-C(4) 1.375(7)
C(4)-C(5) 1.379(7)
C(5)-C(6) 1.390(7)
C(7)-C(12) 1.377(6)
C(7)-C(8) 1.381(6)
C(8)-C(9) 1.372(6)
C(9)-C(10) 1.383(7)
C(10)-C(11) 1.372(7)
C(11)-C(12) 1.390(6)
C(13)-C(14) 1.336(6)
C(21)-C(26) 1.376(6)
C(21)-C(22) 1.385(6)
C(22)-C(23) 1.383(6)
C(23)-C(24) 1.372(7)
C(24)-C(25) 1.387(6)
C(25)-C(26) 1.389(6)
C(13)-C(18) 1.506(6)
C(14)-C(15) 1.506(6)
C(16)-C(19) 1.494(6)
C(17)-C(20) 1.516(6)
C(15)-C(16) 1.551(6)
C(16)-C(17) 1.538(6)
C(17)-C(18) 1.529(6)
N(2)-C(27) 1.110(8) C(27)-C(28) 1.470(11)
O(6)#1-K(1)-O(3) 162.11(9)
O(6)#1-K(1)-O(2)#1 86.86(11)
O(3)-K(1)-O(2)#1 110.66(11)
O(6)#1-K(1)-O(1) 117.21(10)
237
O(3)-K(1)-O(1) 49.53(9)
O(2)#1-K(1)-O(1) 126.64(10)
O(6)#1-K(1)-N(2) 92.90(17)
O(3)-K(1)-N(2) 91.33(16)
O(2)#1-K(1)-N(2) 88.16(14)
O(1)-K(1)-N(2) 132.53(14)
O(6)#1-K(1)-O(4)#1 77.23(10)
O(3)-K(1)-O(4)#1 111.38(9)
O(2)#1-K(1)-O(4)#1 48.05(8)
O(1)-K(1)-O(4)#1 89.28(9)
N(2)-K(1)-O(4)#1 135.01(14)
O(6)#1-K(1)-O(5)#2 66.63(10)
O(3)-K(1)-O(5)#2 98.51(10)
O(2)#1-K(1)-O(5)#2 144.57(10)
O(1)-K(1)-O(5)#2 87.53(9)
N(2)-K(1)-O(5)#2 71.02(15)
O(4)#1-K(1)-O(5)#2 137.18(9)
O(4)-Si(1)-O(1) 133.91(15)
O(4)-Si(1)-O(3) 88.91(15)
O(1)-Si(1)-O(3) 85.07(14)
O(4)-Si(1)-O(2) 85.00(15)
O(1)-Si(1)-O(2) 88.43(14)
O(3)-Si(1)-O(2) 163.90(15)
O(4)-Si(1)-C(13) 113.96(17)
O(1)-Si(1)-C(13) 112.13(17)
O(3)-Si(1)-C(13) 97.07(17)
O(2)-Si(1)-C(13) 99.03(17)
C(1)-O(1)-Si(1) 113.2(2)
C(1)-O(1)-K(1) 136.8(2)
Si(1)-O(1)-K(1) 101.74(13)
C(2)-O(2)-Si(1) 112.9(3)
C(2)-O(2)-K(1)#3 132.2(2)
Si(1)-O(2)-K(1)#3 113.20(14)
C(7)-O(3)-Si(1) 111.6(3)
C(7)-O(3)-K(1) 143.3(2)
Si(1)-O(3)-K(1) 105.08(13)
C(8)-O(4)-Si(1) 112.8(2)
C(8)-O(4)-K(1)#3 139.2(2)
Si(1)-O(4)-K(1)#3 104.89(14)
C(19)-O(5)-K(1)#4 118.2(3)
C(20)-O(6)-K(1)#3 150.8(3)
C(20)-N(1)-C(19) 112.3(4)
C(20)-N(1)-C(21) 123.5(3)
C(19)-N(1)-C(21) 123.8(4)
C(6)-C(1)-O(1) 125.4(4)
C(6)-C(1)-C(2) 121.9(4)
O(1)-C(1)-C(2) 112.8(4)
O(2)-C(2)-C(3) 127.6(4)
O(2)-C(2)-C(1) 112.4(4)
C(3)-C(2)-C(1) 120.0(4)
C(2)-C(3)-C(4) 118.9(5)
C(3)-C(4)-C(5) 120.8(5)
C(4)-C(5)-C(6) 121.0(5)
C(1)-C(6)-C(5) 117.4(5)
O(3)-C(7)-C(12) 125.9(4)
O(3)-C(7)-C(8) 112.8(4)
C(12)-C(7)-C(8) 121.2(4)
O(4)-C(8)-C(9) 126.0(4)
O(4)-C(8)-C(7) 113.1(4)
C(9)-C(8)-C(7) 120.9(4)
238
C(8)-C(9)-C(10) 118.5(5)
C(11)-C(10)-C(9) 120.5(5)
C(10)-C(11)-C(12) 121.5(5)
C(7)-C(12)-C(11) 117.4(5)
C(14)-C(13)-C(18) 114.3(4)
C(14)-C(13)-Si(1) 123.2(3)
C(18)-C(13)-Si(1) 122.5(3)
C(13)-C(14)-C(15) 121.4(4)
O(5)-C(19)-N(1) 122.9(4)
O(5)-C(19)-C(16) 128.7(4)
N(1)-C(19)-C(16) 108.4(4)
O(6)-C(20)-N(1) 124.1(4)
O(6)-C(20)-C(17) 127.0(4)
N(1)-C(20)-C(17) 108.9(4)
C(26)-C(21)-C(22) 121.6(4)
C(26)-C(21)-N(1) 120.2(4)
C(22)-C(21)-N(1) 118.2(4)
C(23)-C(22)-C(21) 118.7(4)
C(24)-C(23)-C(22) 120.4(4)
C(23)-C(24)-C(25) 120.6(5)
C(24)-C(25)-C(26) 119.5(4)
C(21)-C(26)-C(25) 119.1(4)
C(14)-C(15)-C(16) 111.1(4)
C(19)-C(16)-C(17) 105.6(4)
C(19)-C(16)-C(15) 109.5(4)
C(17)-C(16)-C(15) 111.5(4)
C(20)-C(17)-C(18) 109.5(3)
C(20)-C(17)-C(16) 103.4(4)
C(18)-C(17)-C(16) 113.8(4)
C(13)-C(18)-C(17) 109.5(4)
C(27)-N(2)-K(1) 144.9(6) N(2)-C(27)-C(28) 178.5(8)
239
______________________________________________________________________________ a The numbers in parentheses are the estimated standard deviations in the last significant digit. b Atoms are labeled in agreement with Figures 1 and 2.
c Symmetry transformations used to generate equivalent atoms:
#1 -x+1,y-1/2,-z+1/2 #2 x-1,y,z #3 -x+1,y+1/2,-z+1/2 #4 x+1,y,z
240
Table 4. Anisotropic displacement parameters (Å2x 103) for K[Si(O2C6H4)2(C14H12NO2)]-MeCN a,b,c ______________________________________________________________________________
U11 U22 U33 U23 U13 U12
______________________________________________________________________________
K(1) 36(1) 23(1) 45(1) -1(1) -3(1) 1(1)
Si(1) 23(1) 23(1) 30(1) 0(1) 4(1) -3(1)
O(1) 22(2) 27(2) 34(2) 1(1) 3(1) -2(1)
O(2) 26(2) 33(2) 32(2) 6(1) -1(1) -4(1)
O(3) 32(2) 25(2) 29(2) -3(1) 4(1) -5(1)
O(4) 35(2) 22(2) 35(2) -1(1) 6(1) -3(1)
O(5) 62(2) 29(2) 74(3) -1(2) -24(2) 16(2)
O(6) 36(2) 30(2) 54(2) 9(2) -3(2) -2(1)
N(1) 18(2) 23(2) 47(2) 2(2) 1(2) 1(2)
C(1) 27(2) 24(2) 28(3) -3(2) 6(2) 3(2)
C(2) 25(2) 23(2) 34(3) -5(2) 2(2) 1(2)
C(3) 42(3) 38(3) 37(3) 3(2) 7(2) -3(2)
C(4) 52(3) 59(4) 35(3) 2(3) -5(3) 0(3)
C(5) 39(3) 51(3) 46(3) -5(3) -11(3) -2(2)
C(6) 27(3) 38(3) 43(3) -8(2) -3(2) -3(2)
C(7) 20(2) 31(2) 32(3) -4(2) 0(2) 4(2)
C(8) 22(2) 29(2) 39(3) -8(2) 5(2) 2(2)
C(9) 28(3) 36(3) 50(3) -13(2) 6(2) 0(2)
C(10) 33(3) 54(3) 52(4) -29(3) 1(3) -1(2)
C(11) 38(3) 58(4) 37(3) -9(3) 3(2) 0(2)
C(12) 39(3) 43(3) 36(3) -1(2) -2(2) -1(2)
C(13) 21(2) 26(2) 35(3) -8(2) 5(2) -5(2)
C(14) 29(3) 21(2) 48(3) 1(2) 7(2) -4(2)
C(15) 37(3) 29(3) 57(3) -3(2) 14(2) 3(2)
C(16) 29(3) 24(2) 50(3) -9(2) 3(2) 5(2)
C(17) 30(3) 32(2) 35(3) -5(2) 5(2) 1(2)
C(18) 27(3) 36(3) 33(3) -6(2) 2(2) 2(2)
C(19) 33(3) 32(3) 53(3) 1(2) 6(2) 8(2)
C(20) 14(2) 31(3) 41(3) 4(2) 2(2) -3(2)
C(21) 26(2) 22(2) 38(3) 4(2) 4(2) 3(2)
C(22) 22(2) 39(3) 42(3) 2(2) 5(2) 4(2)
C(23) 46(3) 38(3) 38(3) 2(2) 11(2) 13(2)
241
C(24) 50(3) 39(3) 34(3) -4(2) 1(2) 3(2)
C(25) 30(3) 40(3) 40(3) 3(2) -3(2) 3(2)
C(26) 24(2) 27(2) 42(3) 3(2) 2(2) 5(2)
N(2) 109(5) 97(5) 55(4) 15(3) 1(4) 30(4)
C(27) 73(5) 70(5) 70(5) -7(4) -15(4) 17(4)
C(28) 79(6) 123(7) 157(9) -2(6) 31(6) -6(5)
______________________________________________________________________________ a The numbers in parentheses are the estimated standard deviations in the last significant digit. b The form of the anisotropic thermal parameter is: exp[-2π2 (U11h
2a*2 + U22k2b*2 + U33l
2c*2 + 2U12hka*b* + 2U13hla*c* + 2U23klb*c*)].
c Atoms are labeled in agreement with Figures 1 and 2.
242
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3) for K[Si(O2C6H4)2(C14H12NO2)]-MeCN
a,b ______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
H(3) 4052 8807 696 46
H(4) 2105 8239 128 59
H(5) 700 7014 560 56
H(6) 1229 6304 1577 44
H(9) 6309 10030 3833 45
H(10) 6337 9713 4914 56
H(11) 5625 8049 5282 53
H(12) 4803 6661 4584 47
H(14) 6424 5566 3246 39
H(15A) 7522 4265 2419 48
H(15B) 8220 4456 3110 48
H(16) 9551 4937 2208 41
H(17) 8954 6402 1614 39
H(18A) 6720 7039 1587 39
H(18B) 6749 5723 1587 39
H(22) 8365 8467 3566 41
H(23) 9137 9761 4326 49
H(24) 11377 9939 4615 49
H(25) 12889 8822 4157 44
H(26) 12130 7542 3381 37
H(28A) 697 3717 5029 177
H(28B) 1512 4451 5547 177
H(28C) 1943 3211 5436 177
______________________________________________________________________________ a The hydrogen atoms were included in the structural model as fixed atoms (using idealized sp2- or sp3-
hybridized geometry and C-H bond lengths of 0.94 – 0.99 Å) "riding" on their respective carbon atoms. The isotropic thermal parameters for all hydrogen atoms were fixed at a value 1.2(non-methyl) or 1.5(methyl) times the equivalent isotropic thermal parameter of the carbon atom to which they are covalently bonded.
b Hydrogen atoms are labeled with the same numerical subscript(s) as their respective carbon atoms with an additional literal subscript (a, b or c) where necessary to distinguish between hydrogens bonded to the same carbon atom.
243
Table 6. Torsion angles [°] for K[Si(O2C6H4)2(C14H12NO2)]-MeCN ________________________________________________________________
O(6)#1-K(1)-Si(1)-O(4) 138.50(19)
O(3)-K(1)-Si(1)-O(4) -11.42(19)
O(2)#1-K(1)-Si(1)-O(4) -109.45(17)
O(1)-K(1)-Si(1)-O(4) 116.5(2)
N(2)-K(1)-Si(1)-O(4) -10.4(2)
O(4)#1-K(1)-Si(1)-O(4) -154.11(13)
O(5)#2-K(1)-Si(1)-O(4) 66.39(18)
Si(1)#1-K(1)-Si(1)-O(4) -136.00(16)
O(6)#1-K(1)-Si(1)-O(1) 22.04(18)
O(3)-K(1)-Si(1)-O(1) -127.89(19)
O(2)#1-K(1)-Si(1)-O(1) 134.09(14)
N(2)-K(1)-Si(1)-O(1) -126.91(19)
O(4)#1-K(1)-Si(1)-O(1) 89.42(14)
O(5)#2-K(1)-Si(1)-O(1) -50.07(15)
Si(1)#1-K(1)-Si(1)-O(1) 107.54(14)
O(6)#1-K(1)-Si(1)-O(3) 149.92(18)
O(2)#1-K(1)-Si(1)-O(3) -98.02(15)
O(1)-K(1)-Si(1)-O(3) 127.89(19)
N(2)-K(1)-Si(1)-O(3) 0.98(19)
O(4)#1-K(1)-Si(1)-O(3) -142.69(14)
O(5)#2-K(1)-Si(1)-O(3) 77.82(15)
Si(1)#1-K(1)-Si(1)-O(3) -124.58(14)
O(6)#1-K(1)-Si(1)-O(2) -7.8(2)
O(3)-K(1)-Si(1)-O(2) -157.7(2)
O(2)#1-K(1)-Si(1)-O(2) 104.26(16)
O(1)-K(1)-Si(1)-O(2) -29.83(18)
N(2)-K(1)-Si(1)-O(2) -156.7(2)
O(4)#1-K(1)-Si(1)-O(2) 59.59(16)
O(5)#2-K(1)-Si(1)-O(2) -79.90(17)
Si(1)#1-K(1)-Si(1)-O(2) 77.70(15)
O(6)#1-K(1)-Si(1)-C(13) -103.91(19)
O(3)-K(1)-Si(1)-C(13) 106.17(19)
O(2)#1-K(1)-Si(1)-C(13) 8.15(15)
O(1)-K(1)-Si(1)-C(13) -125.94(19)
244
N(2)-K(1)-Si(1)-C(13) 107.1(2)
O(4)#1-K(1)-Si(1)-C(13) -36.52(15)
O(5)#2-K(1)-Si(1)-C(13) -176.01(15)
Si(1)#1-K(1)-Si(1)-C(13) -18.41(13)
O(6)#1-K(1)-Si(1)-K(1)#3 -48.0(5)
O(3)-K(1)-Si(1)-K(1)#3 162.1(5)
O(2)#1-K(1)-Si(1)-K(1)#3 64.1(5)
O(1)-K(1)-Si(1)-K(1)#3 -70.0(5)
N(2)-K(1)-Si(1)-K(1)#3 163.1(5)
O(4)#1-K(1)-Si(1)-K(1)#3 19.4(5)
O(5)#2-K(1)-Si(1)-K(1)#3 -120.1(5)
Si(1)#1-K(1)-Si(1)-K(1)#3 37.5(4)
O(4)-Si(1)-O(1)-C(1) 86.8(3)
O(3)-Si(1)-O(1)-C(1) 170.5(3)
O(2)-Si(1)-O(1)-C(1) 5.2(3)
C(13)-Si(1)-O(1)-C(1) -93.9(3)
K(1)-Si(1)-O(1)-C(1) -154.1(3)
K(1)#3-Si(1)-O(1)-C(1) 20.3(3)
O(4)-Si(1)-O(1)-K(1) -119.13(19)
O(3)-Si(1)-O(1)-K(1) -35.41(12)
O(2)-Si(1)-O(1)-K(1) 159.34(13)
C(13)-Si(1)-O(1)-K(1) 60.23(19)
K(1)#3-Si(1)-O(1)-K(1) 174.41(5)
O(6)#1-K(1)-O(1)-C(1) -21.4(3)
O(3)-K(1)-O(1)-C(1) 173.1(4)
O(2)#1-K(1)-O(1)-C(1) 86.4(3)
N(2)-K(1)-O(1)-C(1) -144.7(4)
O(4)#1-K(1)-O(1)-C(1) 53.8(3)
O(5)#2-K(1)-O(1)-C(1) -83.5(3)
Si(1)-K(1)-O(1)-C(1) 144.1(4)
Si(1)#1-K(1)-O(1)-C(1) 61.0(3)
O(6)#1-K(1)-O(1)-Si(1) -165.50(12)
O(3)-K(1)-O(1)-Si(1) 29.06(11)
O(2)#1-K(1)-O(1)-Si(1) -57.69(17)
N(2)-K(1)-O(1)-Si(1) 71.2(2)
O(4)#1-K(1)-O(1)-Si(1) -90.27(13)
245
O(5)#2-K(1)-O(1)-Si(1) 132.44(14)
Si(1)#1-K(1)-O(1)-Si(1) -83.12(13)
O(4)-Si(1)-O(2)-C(2) -139.3(3)
O(1)-Si(1)-O(2)-C(2) -4.9(3)
O(3)-Si(1)-O(2)-C(2) -71.1(6)
C(13)-Si(1)-O(2)-C(2) 107.2(3)
K(1)-Si(1)-O(2)-C(2) 17.7(3)
K(1)#3-Si(1)-O(2)-C(2) -166.9(3)
O(4)-Si(1)-O(2)-K(1)#3 27.62(15)
O(1)-Si(1)-O(2)-K(1)#3 161.96(14)
O(3)-Si(1)-O(2)-K(1)#3 95.8(5)
C(13)-Si(1)-O(2)-K(1)#3 -85.89(18)
K(1)-Si(1)-O(2)-K(1)#3 -175.43(5)
O(4)-Si(1)-O(3)-C(7) -8.7(3)
O(1)-Si(1)-O(3)-C(7) -142.9(3)
O(2)-Si(1)-O(3)-C(7) -76.4(6)
C(13)-Si(1)-O(3)-C(7) 105.3(3)
K(1)-Si(1)-O(3)-C(7) 179.3(3)
K(1)#3-Si(1)-O(3)-C(7) 1.5(3)
O(4)-Si(1)-O(3)-K(1) 172.00(13)
O(1)-Si(1)-O(3)-K(1) 37.74(13)
O(2)-Si(1)-O(3)-K(1) 104.3(5)
C(13)-Si(1)-O(3)-K(1) -73.99(17)
K(1)#3-Si(1)-O(3)-K(1) -177.86(6)
O(6)#1-K(1)-O(3)-C(7) 105.6(5)
O(2)#1-K(1)-O(3)-C(7) -86.7(4)
O(1)-K(1)-O(3)-C(7) 152.2(4)
N(2)-K(1)-O(3)-C(7) 1.9(4)
O(4)#1-K(1)-O(3)-C(7) -138.4(4)
O(5)#2-K(1)-O(3)-C(7) 72.9(4)
Si(1)-K(1)-O(3)-C(7) -179.0(5)
Si(1)#1-K(1)-O(3)-C(7) -111.9(4)
O(6)#1-K(1)-O(3)-Si(1) -75.5(4)
O(2)#1-K(1)-O(3)-Si(1) 92.32(14)
O(1)-K(1)-O(3)-Si(1) -28.80(11)
N(2)-K(1)-O(3)-Si(1) -179.15(17)
246
O(4)#1-K(1)-O(3)-Si(1) 40.61(15)
O(5)#2-K(1)-O(3)-Si(1) -108.15(14)
Si(1)#1-K(1)-O(3)-Si(1) 67.06(14)
O(1)-Si(1)-O(4)-C(8) 89.2(3)
O(3)-Si(1)-O(4)-C(8) 7.1(3)
O(2)-Si(1)-O(4)-C(8) 172.2(3)
C(13)-Si(1)-O(4)-C(8) -90.2(3)
K(1)-Si(1)-O(4)-C(8) 15.4(3)
K(1)#3-Si(1)-O(4)-C(8) -163.9(3)
O(1)-Si(1)-O(4)-K(1)#3 -106.93(19)
O(3)-Si(1)-O(4)-K(1)#3 170.97(13)
O(2)-Si(1)-O(4)-K(1)#3 -23.95(13)
C(13)-Si(1)-O(4)-K(1)#3 73.72(19)
K(1)-Si(1)-O(4)-K(1)#3 179.30(6)
Si(1)-O(1)-C(1)-C(6) 177.3(3)
K(1)-O(1)-C(1)-C(6) 36.0(6)
Si(1)-O(1)-C(1)-C(2) -4.4(4)
K(1)-O(1)-C(1)-C(2) -145.8(3)
Si(1)-O(2)-C(2)-C(3) -177.8(4)
K(1)#3-O(2)-C(2)-C(3) 18.5(6)
Si(1)-O(2)-C(2)-C(1) 3.5(4)
K(1)#3-O(2)-C(2)-C(1) -160.2(3)
C(6)-C(1)-C(2)-O(2) 178.9(4)
O(1)-C(1)-C(2)-O(2) 0.6(5)
C(6)-C(1)-C(2)-C(3) 0.0(6)
O(1)-C(1)-C(2)-C(3) -178.3(4)
O(2)-C(2)-C(3)-C(4) -179.2(4)
C(1)-C(2)-C(3)-C(4) -0.5(6)
C(2)-C(3)-C(4)-C(5) 0.7(7)
C(3)-C(4)-C(5)-C(6) -0.4(8)
O(1)-C(1)-C(6)-C(5) 178.4(4)
C(2)-C(1)-C(6)-C(5) 0.3(6)
C(4)-C(5)-C(6)-C(1) -0.1(7)
Si(1)-O(3)-C(7)-C(12) -175.1(4)
K(1)-O(3)-C(7)-C(12) 3.8(7)
Si(1)-O(3)-C(7)-C(8) 8.2(4)
247
K(1)-O(3)-C(7)-C(8) -172.9(3)
Si(1)-O(4)-C(8)-C(9) 176.9(4)
K(1)#3-O(4)-C(8)-C(9) 21.1(6)
Si(1)-O(4)-C(8)-C(7) -4.0(4)
K(1)#3-O(4)-C(8)-C(7) -159.7(3)
O(3)-C(7)-C(8)-O(4) -2.9(5)
C(12)-C(7)-C(8)-O(4) -179.7(4)
O(3)-C(7)-C(8)-C(9) 176.3(4)
C(12)-C(7)-C(8)-C(9) -0.5(6)
O(4)-C(8)-C(9)-C(10) 180.0(4)
C(7)-C(8)-C(9)-C(10) 0.9(6)
C(8)-C(9)-C(10)-C(11) -0.2(7)
C(9)-C(10)-C(11)-C(12) -0.9(7)
O(3)-C(7)-C(12)-C(11) -177.0(4)
C(8)-C(7)-C(12)-C(11) -0.5(6)
C(10)-C(11)-C(12)-C(7) 1.3(7)
O(4)-Si(1)-C(13)-C(14) 89.5(4)
O(1)-Si(1)-C(13)-C(14) -90.0(4)
O(3)-Si(1)-C(13)-C(14) -2.4(4)
O(2)-Si(1)-C(13)-C(14) 178.0(4)
K(1)-Si(1)-C(13)-C(14) -47.5(3)
K(1)#3-Si(1)-C(13)-C(14) 136.4(4)
O(4)-Si(1)-C(13)-C(18) -89.4(4)
O(1)-Si(1)-C(13)-C(18) 91.1(3)
O(3)-Si(1)-C(13)-C(18) 178.6(3)
O(2)-Si(1)-C(13)-C(18) -0.9(4)
K(1)-Si(1)-C(13)-C(18) 133.5(3)
K(1)#3-Si(1)-C(13)-C(18) -42.6(3)
C(18)-C(13)-C(14)-C(15) -1.6(6)
Si(1)-C(13)-C(14)-C(15) 179.4(3)
C(13)-C(14)-C(15)-C(16) 46.6(6)
C(14)-C(15)-C(16)-C(19) 80.2(5)
C(14)-C(15)-C(16)-C(17) -36.2(5)
C(19)-C(16)-C(17)-C(20) -11.5(4)
C(15)-C(16)-C(17)-C(20) 107.4(4)
C(19)-C(16)-C(17)-C(18) -130.2(4)
248
C(15)-C(16)-C(17)-C(18) -11.3(5)
C(14)-C(13)-C(18)-C(17) -49.3(5)
Si(1)-C(13)-C(18)-C(17) 129.8(3)
C(20)-C(17)-C(18)-C(13) -60.1(5)
C(16)-C(17)-C(18)-C(13) 55.1(5)
K(1)#4-O(5)-C(19)-N(1) -100.0(5)
K(1)#4-O(5)-C(19)-C(16) 82.4(6)
C(20)-N(1)-C(19)-O(5) 177.0(4)
C(21)-N(1)-C(19)-O(5) -9.0(7)
C(20)-N(1)-C(19)-C(16) -5.0(5)
C(21)-N(1)-C(19)-C(16) 169.0(4)
C(17)-C(16)-C(19)-O(5) -171.7(5)
C(15)-C(16)-C(19)-O(5) 68.1(6)
C(17)-C(16)-C(19)-N(1) 10.4(5)
C(15)-C(16)-C(19)-N(1) -109.8(4)
K(1)#3-O(6)-C(20)-N(1) -131.4(5)
K(1)#3-O(6)-C(20)-C(17) 48.9(9)
C(19)-N(1)-C(20)-O(6) 177.4(4)
C(21)-N(1)-C(20)-O(6) 3.5(6)
C(19)-N(1)-C(20)-C(17) -2.8(5)
C(21)-N(1)-C(20)-C(17) -176.8(4)
C(18)-C(17)-C(20)-O(6) -49.6(6)
C(16)-C(17)-C(20)-O(6) -171.3(4)
C(18)-C(17)-C(20)-N(1) 130.7(4)
C(16)-C(17)-C(20)-N(1) 9.0(4)
C(20)-N(1)-C(21)-C(26) -125.5(4)
C(19)-N(1)-C(21)-C(26) 61.2(6)
C(20)-N(1)-C(21)-C(22) 54.5(6)
C(19)-N(1)-C(21)-C(22) -118.8(5)
C(26)-C(21)-C(22)-C(23) 1.6(7)
N(1)-C(21)-C(22)-C(23) -178.4(4)
C(21)-C(22)-C(23)-C(24) -0.9(7)
C(22)-C(23)-C(24)-C(25) -0.3(7)
C(23)-C(24)-C(25)-C(26) 0.9(7)
C(22)-C(21)-C(26)-C(25) -1.0(7)
N(1)-C(21)-C(26)-C(25) 179.0(4)
249
C(24)-C(25)-C(26)-C(21) -0.3(7)
O(6)#1-K(1)-N(2)-C(27) -25.5(10)
O(3)-K(1)-N(2)-C(27) 137.1(10)
O(2)#1-K(1)-N(2)-C(27) -112.2(10)
O(1)-K(1)-N(2)-C(27) 106.4(10)
O(4)#1-K(1)-N(2)-C(27) -100.3(10)
O(5)#2-K(1)-N(2)-C(27) 38.6(10)
Si(1)-K(1)-N(2)-C(27) 136.7(10)
Si(1)#1-K(1)-N(2)-C(27) -98.3(10)
K(1)-N(2)-C(27)-C(28) 123(36)
________________________________________________________________
Symmetry transformations used to generate equivalent atoms:
#1 -x+1,y-1/2,-z+1/2 #2 x-1,y,z #3 -x+1,y+1/2,-z+1/2
#4 x+1,y,z
250
Unit cell of 13.1.1d not showing Head-to-Tail packing
(Counter ion, K+ was seen coordinated with a molecule of acetonitrile)
251
Appendix G
NMR Kinetic Study of Dienes, 13.1.2a, 13.1.2d & 11.3.2b
252
Comparitive Reactivities Studies in between (Buta-1,3-dien-2-yl)silatrane (13.1.2a),
Danishefsky’s Diene (13.1.2d) and (Buta-1,3-dien-2-yl)triethoxysilane (11.3.2b) against N-
Phenylmaleimide (9.1.4b) using NMR Kinetic Experiments.
General: 1H NMR kinetics data were collected on a Bruker DRX 500 spectrometer using a 5 mm
BBO probe at 273 K (0oC) using variable temperature regulation. A standard Bruker zg30 pulse
sequence of 16 scans with a recycle delay of one second was used. Experiments were arrayed
using a variable delay list arranged according to the progress of reaction. Typically, a spectrum
was collected every 15 minutes during the first 2 half lives and then every 30 minutes during the
third and fourth half lives and finally every hour for the fifth and final half life. After data
collection the 2D serial file was split into individual FIDs and all data were processed with a
standard exponential window function and all integrals corrected for slope and bias defects.
Disappearance of the diene was monitored by integrating the vinyl proton signals relative to the
TMS signal at 0 ppm. Rate constants determined from appearance of the cycloadduct integrals
consistently had larger errors and were not used in the reported average values. Sigma Plot 9.0
(Systat Software, Inc.) was used to plot the integral values for the disappearance of diene peaks
as a function of time (ref supplemental see below). Under the pseudo-first order conditions
employed a first order exponential decay curve fit (I = I0e-kt) was performed to determine the rate
constant and error. (Buta-1,3-dien-2-yl)silatrane (13.1.2a) gave an average observed rate
constant of kobs = 0.037 min-1 +/- 0.003 min-1 t1/2 = 19 min. and Danishefsky’s diene (13.1.2d)
gave kobs = 0.021 min-1 +/- 0.001 min-1 t1/2 = 33 min. Whereas, the (buta-1,3-dien-2-
yl)triethoxysilane (11.3.2b) had not reached t1/2 by 10 hours under these conditions.
Sample Preparation: Experiment 1: N-Phenylmaleimide, 9.1.4b (0.121 g, 0.699 mmol) was
dissolved in ice-cold CDCl3 having TMS (1% v/v) in a NMR tube. (Buta-1,3-dien-2-yl)silatrane
253
(13.1.2a) (0.025 g, 0.110 mmol) pre-dissolved in ice-cold CDCl3 was added to the NMR tube.
Overall, 15 sets of FID’s were collected (with an interval of 15 min.) starting 15 min. after
mixing.
Experiment 2: N-Phenylmaleimide, 9.1.4b (0.117 g, 0.676 mmol) was dissolved in ice-cold
CDCl3 having TMS (1% v/v) in a NMR tube. Danishefsky’s diene (13.1.2d) (0.052 g, 0.302
mmol) pre-dissolved in ice-cold CDCl3 was added to the NMR tube. Overall, 15 sets of FID’s
were collected starting 15 min. after mixing. First Four intermittent FID’s were collected at every
15 min. followed by 30 min. intervals.
Experiment 3: N-Phenylmaleimide, 9.1.4b (0.08 g, 0.462 mmol) was dissolved in ice-cold
CDCl3 having TMS (1% v/v) in a NMR tube. (Buta-1,3-dien-2-yl)triethoxysilane (11.3.2b)
(0.020 g, 0.093 mmol) pre-dissolved in ice-cold CDCl3 was added to the NMR tube. Overall, 15
sets of FID’s were collected starting 15 min. after mixing. First Four intermittent FID’s were
collected at every 15 min. followed by 30 min. intervals.
254
(13.1.2a) (13.1.1c)
NMR Kinetics of Silyl Diene, 13.1.2a with N-Phenylmaleimide, 9.1.4b
13.1.1c13.1.2a13.1.2a
13.1.1c
13.1.1c
255
Danishefsky's Diene Integration vs. Time
Time (min)
0 100 200 300 400 500
Inte
gra
tion
0
1
2
3
4
5.38 ppm
4.13 ppm
3.58 ppm
10
1 2
3
4
N
O
O
5
6
7
3a
7a
11 12
13
TMSO
OMe
(13.1.1f)
TMSO
OMe
(13.1.2d)
13.1.2d 13.1.2d
13.1.2d
13.1.1f13.1.1f 13.1.1f
13.1.1f
NMR Kinetics of Danishefsky's Diene, 13.1.2d with N-Phenylmaleimide, 9.1.4b
256
NMR Kinetics of Diene, 11.3.2b with N-Phenylmaleimide, 9.1.4b
257
Appendix H
Graphic Representation of 13.1.3a, b and 13.1.4a, b showing
NOE (Nuclear Overhauser Effect) peaks
258
259
Appendix I
Crystallographic Data for 13.1.3a and 13.1.3b
Major Isomer (13.1.3a) Minor Isomer (13.1.3b)
260
Table 1. Crystal data and structure refinement for C15H21NO6Si
Empirical formula C15H21NO6Si
Formula weight 339.42
Temperature 193(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic Space group P2(1)/c- C 5
2h(No. 14)
Unit cell dimensions a = 11.545(2) Å
b = 10.647(2) Å, β = 96.352(3)°
c = 12.953(3) Å
Volume 1582.4(6) Å3
Z 4
Density (calculated) 1.425 g/cm3
Absorption coefficient 0.180 mm-1
F(000) 720
Crystal size 0.54 x 0.23 x 0.02 mm3
Theta range for data collection 3.95 to 27.48°
Index ranges -14≤h≤14, -13≤k≤13, -16≤l≤16
Reflections collected 13680
Independent reflections 3595 [R(int) = 0.0540]
Completeness to theta = 27.48° 99.0 %
Absorption correction Multi-scan (SADABS)
Refinement method Full-matrix least-squares on F2
Data / parameters 3595 / 221
Goodness-of-fit on F2 1.035
Final R indices [I>2sigma(I)] R1 = 0.0677, wR2 = 0.1725
R indices (all data) R1 = 0.0977, wR2 = 0.1916
Largest diff. peak and hole 0.677 and -0.375 e-/Å3
261
Table 2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x
103) for C15H21NO6Si. U(eq) is defined as one third of the trace of the orthogonalized Uij
tensor.
______________________________________________________________________________
x y z U(eq)
______________________________________________________________________________
Si(1) 381(1) 2518(1) 3102(1) 27(1)
O(1) 565(2) 2718(2) 1858(2) 35(1)
O(2) 235(2) 3780(2) 3832(2) 33(1)
O(3) -112(2) 1140(2) 3493(2) 34(1)
O(4) 4167(2) 4548(2) 3732(2) 64(1)
O(5) 5251(3) 3507(4) 2688(4) 106(1)
O(6) 3113(3) 5092(3) 4962(3) 96(1)
N(1) -1405(2) 2829(2) 2569(2) 30(1)
C(1) -375(3) 2868(3) 1068(2) 43(1)
C(2) -1393(3) 3439(3) 1547(2) 41(1)
C(3) -811(2) 4502(3) 3745(2) 33(1)
C(4) -1821(3) 3656(3) 3361(2) 36(1)
C(5) -1316(3) 830(3) 3399(3) 39(1)
C(6) -1938(3) 1574(3) 2515(3) 41(1)
C(7) 1949(3) 2179(3) 3568(3) 37(1)
C(8) 2718(3) 1726(3) 2946(3) 50(1)
C(9) 3912(3) 1349(4) 3360(4) 70(1)
C(10) 4465(3) 2386(3) 4084(4) 67(1)
C(11) 3678(3) 2891(4) 4818(3) 60(1)
C(12) 2416(3) 2287(4) 4689(3) 54(1)
C(13) 4696(4) 3484(4) 3411(4) 68(1)
C(14) 3597(3) 4272(4) 4563(3) 59(1)
C(15) 5622(4) 1947(5) 4745(5) 68(2)
C(15') 4400(30) 2520(30) 5750(19) 94(10)
______________________________________________________________________________
262
Table 3. Bond lengths [Å] and angles [°] for C15H21NO6Si
___________________________________________________________________________
Si(1)-O(2) 1.662(2)
Si(1)-O(1) 1.663(2)
Si(1)-O(3) 1.671(2)
Si(1)-C(7) 1.879(3)
Si(1)-N(1) 2.126(2)
O(1)-C(1) 1.415(4)
O(2)-C(3) 1.425(3)
O(3)-C(5) 1.420(3)
O(4)-C(14) 1.354(5)
O(4)-C(13) 1.373(5)
O(5)-C(13) 1.191(5) O(6)-C(14) 1.186(5)
N(1)-C(6) 1.470(4)
N(1)-C(4) 1.473(4)
N(1)-C(2) 1.476(4)
C(1)-C(2) 1.516(5)
C(3)-C(4) 1.513(4)
C(5)-C(6) 1.508(5)
C(7)-C(8) 1.352(5)
C(7)-C(12) 1.496(5)
C(8)-C(9) 1.478(5)
C(9)-C(10) 1.542(6)
C(10)-C(11) 1.486(7)
C(10)-C(13) 1.500(6)
C(11)-C(14) 1.508(6)
C(11)-C(12) 1.584(5)
C(10)-C(15) 1.575(6) C(11)-C(15') 1.44(2)
O(2)-Si(1)-O(1) 118.67(11)
O(2)-Si(1)-O(3) 118.55(11)
O(1)-Si(1)-O(3) 119.33(11)
O(2)-Si(1)-C(7) 97.31(12)
O(1)-Si(1)-C(7) 96.54(13)
O(3)-Si(1)-C(7) 94.74(12)
O(2)-Si(1)-N(1) 84.46(10)
O(1)-Si(1)-N(1) 83.60(10)
O(3)-Si(1)-N(1) 83.36(10)
C(7)-Si(1)-N(1) 177.88(11)
C(1)-O(1)-Si(1) 123.01(19)
C(3)-O(2)-Si(1) 121.94(17)
C(5)-O(3)-Si(1) 122.78(19)
C(14)-O(4)-C(13) 109.5(3)
C(6)-N(1)-C(4) 114.2(2)
C(6)-N(1)-C(2) 113.8(2)
C(4)-N(1)-C(2) 113.4(2)
C(6)-N(1)-Si(1) 105.06(18)
C(4)-N(1)-Si(1) 104.25(17)
C(2)-N(1)-Si(1) 104.78(18)
263
O(1)-C(1)-C(2) 108.5(2)
N(1)-C(2)-C(1) 106.0(3)
O(2)-C(3)-C(4) 108.7(2)
N(1)-C(4)-C(3) 106.6(2)
O(3)-C(5)-C(6) 108.8(2)
N(1)-C(6)-C(5) 106.2(2)
C(8)-C(7)-C(12) 114.6(3)
C(8)-C(7)-Si(1) 123.4(3)
C(12)-C(7)-Si(1) 121.9(3)
C(7)-C(8)-C(9) 121.9(4)
C(8)-C(9)-C(10) 109.4(3)
C(11)-C(10)-C(13) 104.5(3)
C(11)-C(10)-C(9) 114.0(3)
C(13)-C(10)-C(9) 107.0(4)
C(11)-C(10)-C(15) 107.5(4)
C(13)-C(10)-C(15) 110.6(3)
C(9)-C(10)-C(15) 112.8(4)
C(15')-C(11)-C(10) 95.7(13)
C(15')-C(11)-C(14) 117.7(13)
C(10)-C(11)-C(14) 103.9(4)
C(15')-C(11)-C(12) 114.6(13)
C(10)-C(11)-C(12) 114.0(3)
C(14)-C(11)-C(12) 109.8(3)
C(7)-C(12)-C(11) 111.2(3)
O(5)-C(13)-O(4) 121.2(4)
O(5)-C(13)-C(10) 128.2(4)
O(4)-C(13)-C(10) 110.7(4)
O(6)-C(14)-O(4) 118.7(4)
O(6)-C(14)-C(11) 130.0(5)
O(4)-C(14)-C(11) 111.2(3)
264
________________________________________________________________________
265
Table 4. Anisotropic displacement parameters (Å2x 103) for C15H21NO6Si. The
anisotropic
displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k a* b* U12 ]
________________________________________________________________________
______
U11 U22 U33 U23 U13 U12
________________________________________________________________________
______
Si(1) 27(1) 25(1) 29(1) -3(1) 3(1) -3(1)
O(1) 37(1) 40(1) 31(1) 0(1) 9(1) -2(1)
O(2) 33(1) 32(1) 33(1) -7(1) -2(1) -1(1)
O(3) 30(1) 28(1) 44(1) 2(1) 7(1) -2(1)
O(4) 60(2) 36(1) 97(2) 1(1) 15(2) -2(1)
O(5) 94(3) 90(3) 147(4) -10(2) 66(3) -21(2)
O(6) 93(2) 80(2) 118(3) -49(2) 23(2) -7(2)
N(1) 29(1) 29(1) 33(1) -4(1) 2(1) -3(1)
C(1) 54(2) 46(2) 30(2) -4(1) 5(1) 0(2)
C(2) 43(2) 44(2) 33(2) -3(1) -5(1) 1(1)
C(3) 35(2) 28(1) 35(2) -3(1) 3(1) 3(1)
C(4) 36(2) 34(2) 39(2) -5(1) 6(1) 2(1)
C(5) 35(2) 32(2) 53(2) -3(1) 13(1) -8(1)
C(6) 32(2) 36(2) 52(2) -10(1) 2(1) -8(1)
C(7) 29(2) 27(1) 54(2) 4(1) 2(1) -4(1)
C(8) 38(2) 35(2) 77(3) -8(2) 6(2) -4(1)
C(9) 44(2) 43(2) 122(4) -9(2) 4(2) 2(2)
C(10) 35(2) 38(2) 127(4) 7(2) 0(2) -2(2)
C(11) 50(2) 63(2) 61(2) 6(2) -14(2) -4(2)
C(12) 43(2) 60(2) 56(2) 15(2) -4(2) -3(2)
C(13) 52(2) 58(3) 99(3) -8(2) 29(2) -9(2)
C(14) 44(2) 58(2) 73(3) -25(2) 3(2) -8(2)
C(15) 28(2) 66(3) 108(5) 26(3) -2(2) 4(2)
C(15') 100(20) 130(30) 51(14) 2(13) -20(13) 0(17)
________________________________________________________________________
_____
266
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x 10 3)
for C15H21NO6Si
________________________________________________________________________
_____
x y z U(eq)
________________________________________________________________________
_____
H(1A) -601 2043 756 52
H(1B) -141 3424 515 52
H(2A) -1289 4358 1630 49
H(2B) -2132 3277 1104 49
H(3A) -753 5203 3251 40
H(3B) -935 4860 4429 40
H(4A) -2068 3153 3941 43
H(4B) -2493 4162 3056 43
H(5A) -1644 1031 4054 47
H(5B) -1419 -81 3263 47
H(6A) -1841 1169 1842 49
H(6B) -2781 1631 2589 49
H(8) 2484 1649 2222 73(14)
H(9A) 4388 1214 2779 84
H(9B) 3886 551 3749 84
H(10) 5208 2081 4472 81
H(11) 4044 2775 5548 71
H(12A) 2449 1443 5011 65
H(12B) 1884 2814 5055 65
H(15A) 5964 2655 5155 102
H(15B) 6175 1648 4278 102
H(15C) 5445 1266 5211 102
H(15D) 5016 3147 5912 141
H(15E) 4750 1702 5643 141
H(15F) 3921 2469 6328 141
________________________________________________________________________
_____
267
Table 6. Torsion angles [°] for C15H21NO6Si
________________________________________________________________
O(2)-Si(1)-O(1)-C(1) -85.4(2)
O(3)-Si(1)-O(1)-C(1) 73.4(2)
C(7)-Si(1)-O(1)-C(1) 172.6(2)
N(1)-Si(1)-O(1)-C(1) -5.3(2)
O(1)-Si(1)-O(2)-C(3) 74.3(2)
O(3)-Si(1)-O(2)-C(3) -84.7(2)
C(7)-Si(1)-O(2)-C(3) 175.9(2)
N(1)-Si(1)-O(2)-C(3) -5.3(2)
O(2)-Si(1)-O(3)-C(5) 75.8(2)
O(1)-Si(1)-O(3)-C(5) -83.0(2)
C(7)-Si(1)-O(3)-C(5) 176.7(2)
N(1)-Si(1)-O(3)-C(5) -4.2(2)
O(2)-Si(1)-N(1)-C(6) -138.42(19)
O(1)-Si(1)-N(1)-C(6) 101.85(19)
O(3)-Si(1)-N(1)-C(6) -18.77(19)
C(7)-Si(1)-N(1)-C(6) 8(3)
O(2)-Si(1)-N(1)-C(4) -18.01(18)
O(1)-Si(1)-N(1)-C(4) -137.74(19)
O(3)-Si(1)-N(1)-C(4) 101.64(19)
C(7)-Si(1)-N(1)-C(4) 128(3)
O(2)-Si(1)-N(1)-C(2) 101.42(19)
O(1)-Si(1)-N(1)-C(2) -18.31(19)
O(3)-Si(1)-N(1)-C(2) -138.93(19)
C(7)-Si(1)-N(1)-C(2) -112(3)
Si(1)-O(1)-C(1)-C(2) 27.4(3)
C(6)-N(1)-C(2)-C(1) -79.8(3)
C(4)-N(1)-C(2)-C(1) 147.4(2)
Si(1)-N(1)-C(2)-C(1) 34.4(3)
O(1)-C(1)-C(2)-N(1) -39.6(3)
Si(1)-O(2)-C(3)-C(4) 27.3(3)
C(6)-N(1)-C(4)-C(3) 148.2(2)
C(2)-N(1)-C(4)-C(3) -79.2(3)
Si(1)-N(1)-C(4)-C(3) 34.2(3)
O(2)-C(3)-C(4)-N(1) -39.8(3)
268
Si(1)-O(3)-C(5)-C(6) 26.1(3)
C(4)-N(1)-C(6)-C(5) -79.2(3)
C(2)-N(1)-C(6)-C(5) 148.5(3)
Si(1)-N(1)-C(6)-C(5) 34.4(3)
O(3)-C(5)-C(6)-N(1) -39.0(3)
O(2)-Si(1)-C(7)-C(8) -144.2(3)
O(1)-Si(1)-C(7)-C(8) -24.1(3)
O(3)-Si(1)-C(7)-C(8) 96.2(3)
N(1)-Si(1)-C(7)-C(8) 70(3)
O(2)-Si(1)-C(7)-C(12) 41.3(3)
O(1)-Si(1)-C(7)-C(12) 161.4(3)
O(3)-Si(1)-C(7)-C(12) -78.3(3)
N(1)-Si(1)-C(7)-C(12) -105(3)
C(12)-C(7)-C(8)-C(9) 1.3(5)
Si(1)-C(7)-C(8)-C(9) -173.7(3)
C(7)-C(8)-C(9)-C(10) -47.7(5)
C(8)-C(9)-C(10)-C(11) 44.6(5)
C(8)-C(9)-C(10)-C(13) -70.5(5)
C(8)-C(9)-C(10)-C(15) 167.6(4)
C(13)-C(10)-C(11)-C(15') -124.8(13)
C(9)-C(10)-C(11)-C(15') 118.7(13)
C(15)-C(10)-C(11)-C(15') -7.2(13)
C(13)-C(10)-C(11)-C(14) -4.4(4)
C(9)-C(10)-C(11)-C(14) -121.0(4)
C(15)-C(10)-C(11)-C(14) 113.2(4)
C(13)-C(10)-C(11)-C(12) 115.0(4)
C(9)-C(10)-C(11)-C(12) -1.5(5)
C(15)-C(10)-C(11)-C(12) -127.4(4)
C(8)-C(7)-C(12)-C(11) 44.9(4)
Si(1)-C(7)-C(12)-C(11) -140.1(3)
C(15')-C(11)-C(12)-C(7) -152.7(14)
C(10)-C(11)-C(12)-C(7) -43.7(5)
C(14)-C(11)-C(12)-C(7) 72.3(4)
C(14)-O(4)-C(13)-O(5) -179.9(5)
C(14)-O(4)-C(13)-C(10) 0.0(5)
C(11)-C(10)-C(13)-O(5) -177.0(5)
269
C(9)-C(10)-C(13)-O(5) -55.8(6)
C(15)-C(10)-C(13)-O(5) 67.5(7)
C(11)-C(10)-C(13)-O(4) 3.0(5)
C(9)-C(10)-C(13)-O(4) 124.2(4)
C(15)-C(10)-C(13)-O(4) -112.5(5)
C(13)-O(4)-C(14)-O(6) 178.0(4)
C(13)-O(4)-C(14)-C(11) -3.1(4)
C(15')-C(11)-C(14)-O(6) -72.2(16)
C(10)-C(11)-C(14)-O(6) -176.4(4)
C(12)-C(11)-C(14)-O(6) 61.3(6)
C(15')-C(11)-C(14)-O(4) 109.1(15)
C(10)-C(11)-C(14)-O(4) 4.9(4)
C(12)-C(11)-C(14)-O(4) -117.4(4)
________________________________________________________________
270
Unit cell of 13.1.3a and 13.1.3b not showing Head-to-Tail packing
(Cycloadduct forming through ‘endo’ transition state was only noticed)
271
Appendix J
HMBC NMR Spectra of Catechol Silane Substituted Cycloadduct, 13.1.4c
1
2
6
5
4
3
10 O
O11
12
Si
O
7'
7
O
OO
9
8
H
Major Isomer (13.1.4c)
272
Figure 13.1.6: HMBC (Heteronuclear Multiple Bond Coherence) NMR Spectra of
Cycloadduct, 13.1.4c, Confirms Regiochemistry of Major Cycloadduct
H4 (2.28 ppm)
C2 (131.79 ppm)
1
2
6
5
4
3
10 O
O11
12
Si
O
7'
7
O
OO
9
8
H
Major Isomer (13.1.4c)
273
APPENDIX – K
Strucutral Conformation of 13.2.8a-b (Exo and Endo) and 13.2.9 (Endo) by
2D NMR Spectroscopy
274
Stereochemical Assignment of 13.2.9 (Endo Cycloadduct) by NMR Spectroscopy:
1H NMR of the cycloadduct 13.2.9 was first recorded using CDCl3 was shown that the
protons H5a,8a and H5,8b were overlapping. When the same compound spectrally observed in
benzene-d6 all the protons were seen separated well. Hence all the 1D and 2D NMR data was
collected in C6D6 to prove the structure and stereochemistry of the cycloadduct.
All the protons were assigned by using the 2D COSY NMR spectroscopy. Diastereotopic
protons and carbons to which they were attached were primarily identified by HMQC. HMBC
spectral data was used to clarify the ambiguous carbon assignment and used for identifying the
quaternary carbon centers. NOE data from NOESY spectra was used to find the ring junction
(cis/trans) and to assign the stereochemistry.
Findings:
1. COSY NMR: H5up (1.65ppm) was shown having a cross-peak with H5a
2. NOESY:
a. H10up (0.14ppm) was showing a NOE to H9 (5.02ppm) – concluded as they are
on the same side.
275
b. H10down (0.20ppm) was showing NOE peaks in between H9, 5a, 8b and 5
(4.28ppm, 2.46ppm, 2.15-2.25ppm, 1.65ppm respectively) – concludes as are on
same side.
c. H5down (1.65ppm) having NOE peaks from H5a, 8a and 8b – confirms H5 at
1.65ppm is on same side as bridge-head protons and H8b.
d. H5up (2.56ppm) doesn’t show any NOE from H8a, 8b – confirms that proton (H5)
at 2.56ppm is opposite side to bride-head protons.
276
Si
O
NH
MeO
O
H
HH
HH
HH
H
H
11b (C6D6)[Endo- adduct, major (52.9%]
H
H
no NOE in b.wbridgehead - isopropyl
1
2
3
45 6 7
8
910
11
12
13
1415
165a
8a8b
Si
O
NH
MeO
O
H
HH
HH
HH
H
H
11a (CDCl3)[Exo- adduct, minor (47.1%)]
H
H
no NOE in b.wbridgehead(H5a) - 8b
1
2
3
45 6 7
8
910
11
12
13
1415
165a
8a8b
weak 'NOE'
Stereochemical Assignment of 13.2.8a (Exo Cycloadduct) by NMR Spectroscopy:
1H NMR of this isomer was taken in both CDCl3 and C6D6. It was found that the proton
separation is good when CDCl3 was used. Hence all the 2D NMR spectra data was recorded in
using chloroform-d as the NMR solvent. Stereochemical assignment was made by using NOESY
NMR as follows.
1. H9up (3.90ppm) shows NOE from H8a (2.63ppm) and H11 (1.09, 1.02ppm)
2. H9down (4.64ppm) shows NOE in between H8b (2.51-2.60ppm), H12 (1.96) and H11down (1.02,
1.09ppm)
3. H8bdown (2.51-2.60ppm) has a NOE in between H5down (2.22ppm), H11down (1.02, 1.09ppm) and
also…
4. H8b doesn’t show any NOE to H5a (bride-head) which confirms that they are on opposite side
to each other.
277
Si
O
NH
MeO
O
H
HH
HH
HH
H
H
11b (C6D6)[Endo- adduct, major (52.9%]
H
H
no NOE in b.wbridgehead - isopropyl
1
2
3
45 6 7
8
910
11
12
13
1415
165a
8a8b
Si
O
NH
MeO
O
H
HH
HH
HH
H
H
11a (CDCl3)[Exo- adduct, minor (47.1%)]
H
H
no NOE in b.wbridgehead(H5a) - 8b
1
2
3
45 6 7
8
910
11
12
13
1415
165a
8a8b
weak 'NOE'
Stereochemical Assignment of 13.2.8b (Endo Cycloadduct) by NMR Spectroscopy:
1H NMR of this isomer was taken in both CDCl3 and C6D6. It was found that the proton
separation is good when C6D6 was used. Hence all the 2D NMR used to confirm the
stereochemistry was of taken in C6D6 only.
1. NOE was observed in between the benzene (ortho, H14, 7.40ppm) to H9up (4.94ppm), 5/12
(1.59-1.73ppm) and isopropyl groupup (0.90, 0.94ppm) of silicon.
2. H9down (4.31ppm) show peaks to H8b (2.11-2.26ppm) and isopropyl (1.06ppm) of silicon.
3. H8bdown has the cross-peak between H5a/8a (2.36-2.52ppm), H5 and isopropyldown (1.01ppm).
4. Other H5up (2.64ppm) doesn’t show any NOE cross-peak.
278
Appendix L
Crystallographic Data for Cross Coupled Cycloadduct, 13.3.2e
279
Table 1. Crystal data and structure refinement for C20H16FNO2
Identification code a26n2m
Empirical formula C20 H16 F N O2
Formula weight 321.34
Temperature 193(2) K
Wavelength 0.71073 Å
Crystal system Monoclinic Space group P21/n [an alternate setting of P21/c – C 5
2h
(No. 14)]
Unit cell dimensions a = 14.649(1) Å
b = 6.6182(6) Å, β = 99.662(1)°
c = 17.212(2) Å
Volume 1645.1(3) Å3
Z 4
Density (calculated) 1.297 g/cm3
Absorption coefficient 0.091 mm-1
F(000) 672
Crystal size 0.44 x 0.29 x 0.06 mm3
Theta range for data collection 3.90 to 30.05°
Index ranges -20≤h≤20, -9≤k≤9, -24≤l≤24
Reflections collected 17395
Independent reflections 4776 [R(int) = 0.0286]
Completeness to theta = 30.05° 98.8 %
Absorption correction None
Max. and min. transmission 0.9947 and 0.9609
Refinement method Full-matrix least-squares on F2
Data / parameters 4776 / 217
Goodness-of-fit on F2 1.047
Final R indices [3533 data I>2σ(I)] R1 = 0.0587, wR2 = 0.1539
R indices (all data) R1 = 0.0775, wR2 = 0.1690
Largest diff. peak and hole 0.363 and -0.172 e-/Å3
------------------------------------------------------------------------------------------------------------------------
R1 = Σ ||Fo| - |Fc|| / Σ |Fo|
wR2 = { Σ [w(Fo2
- Fc2
)2
] / Σ [w(Fo2
)2
] }1/2
280
Table 2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters
(Å2x 103) for C20H16FNO2. U(eq) is defined as one third of the trace of the
orthogonalized Uij tensor.
________________________________________________________________________
x y z U(eq)
________________________________________________________________________
F(1) -1506(1) 3730(2) 4266(1) 95(1)
O(1) 102(1) 3378(2) 1919(1) 48(1)
O(2) 2310(1) -1163(2) 2914(1) 60(1)
N(1) 1172(1) 876(2) 2257(1) 34(1)
C(1) 705(1) 2621(2) 2393(1) 36(1)
C(2) 1825(1) 311(2) 2904(1) 41(1)
C(3) 1805(1) 1810(2) 3558(1) 42(1)
C(4) 1058(1) 3338(2) 3225(1) 41(1)
C(5) 239(1) 3453(2) 3687(1) 48(1)
C(6) -48(1) 1351(2) 3885(1) 41(1)
C(7) 619(1) 68(3) 4190(1) 46(1)
C(8) 1612(1) 724(3) 4303(1) 51(1)
C(9) -1035(1) 739(3) 3725(1) 47(1)
C(10) -1736(1) 1950(4) 3904(1) 65(1)
C(11) -2661(1) 1390(5) 3755(1) 91(1)
C(12) -2897(2) -437(6) 3428(1) 98(1)
C(13) -2234(2) -1700(5) 3245(1) 90(1)
C(14) -1305(1) -1134(3) 3390(1) 65(1)
C(15) 1058(1) -170(2) 1516(1) 35(1)
C(16) 1370(1) 725(2) 884(1) 47(1)
C(17) 1289(1) -339(3) 179(1) 58(1)
C(18) 906(1) -2237(3) 111(1) 54(1)
C(19) 602(1) -3110(3) 748(1) 52(1)
C(20) 674(1) -2077(2) 1455(1) 42(1)
________________________________________________________________________
281
Table 3. Bond lengths [Å] and angles [°] for C20H16FNO2
________________________________________________________________________
F(1)-C(10) 1.349(3) N(1)-C(15) 1.4348(16)
O(1)-C(1) 1.2068(16)
O(2)-C(2) 1.2055(18)
N(1)-C(1) 1.3822(17)
N(1)-C(2) 1.3927(16)
C(1)-C(4) 1.514(2)
C(2)-C(3) 1.504(2)
C(5)-C(6) 1.509(2)
C(7)-C(8) 1.500(2)
C(3)-C(4) 1.529(2)
C(3)-C(8) 1.537(2)
C(4)-C(5) 1.549(2)
C(6)-C(7) 1.334(2)
C(6)-C(9) 1.482(2)
C(9)-C(10) 1.377(2)
C(9)-C(14) 1.396(3)
C(10)-C(11) 1.387(3)
C(11)-C(12) 1.354(4)
C(12)-C(13) 1.359(4)
C(13)-C(14) 1.393(3)
C(15)-C(20) 1.379(2)
C(15)-C(16) 1.382(2)
C(16)-C(17) 1.391(2)
C(17)-C(18) 1.373(3)
C(18)-C(19) 1.377(2)
C(19)-C(20) 1.385(2)
C(1)-N(1)-C(2) 112.40(11)
C(1)-N(1)-C(15) 124.52(10)
C(2)-N(1)-C(15) 122.91(11)
O(1)-C(1)-N(1) 123.96(13)
O(1)-C(1)-C(4) 127.22(13)
N(1)-C(1)-C(4) 108.80(11)
O(2)-C(2)-N(1) 123.50(13)
O(2)-C(2)-C(3) 127.52(13)
N(1)-C(2)-C(3) 108.97(12)
C(2)-C(3)-C(4) 104.92(11)
C(2)-C(3)-C(8) 110.20(13)
C(4)-C(3)-C(8) 113.74(12)
C(1)-C(4)-C(3) 104.90(11)
C(1)-C(4)-C(5) 109.21(12)
C(3)-C(4)-C(5) 114.00(12)
C(6)-C(5)-C(4) 109.86(12)
C(7)-C(8)-C(3) 109.69(12)
282
C(7)-C(6)-C(9) 121.73(14)
C(7)-C(6)-C(5) 117.58(14)
C(9)-C(6)-C(5) 120.68(14)
C(6)-C(7)-C(8) 119.82(15)
C(10)-C(9)-C(14) 116.06(17)
C(10)-C(9)-C(6) 122.70(16)
C(14)-C(9)-C(6) 121.24(15)
F(1)-C(10)-C(9) 118.31(16)
F(1)-C(10)-C(11) 118.6(2)
C(9)-C(10)-C(11) 123.0(2)
C(12)-C(11)-C(10) 119.3(2)
C(11)-C(12)-C(13) 120.1(2)
C(12)-C(13)-C(14) 120.6(3)
C(13)-C(14)-C(9) 120.8(2)
C(20)-C(15)-C(16) 121.11(13)
C(20)-C(15)-N(1) 119.62(12)
C(16)-C(15)-N(1) 119.22(12)
C(15)-C(16)-C(17) 118.63(14)
C(18)-C(17)-C(16) 120.75(15)
C(17)-C(18)-C(19) 119.88(15)
C(18)-C(19)-C(20) 120.37(15)
C(15)-C(20)-C(19) 119.27(13)
________________________________________________________________________
283
Table 4. Anisotropic displacement parameters (Å2x 103) for C20H16FNO2. The
anisotropic displacement factor exponent takes the form: -2π2[ h2 a*2U11 + ... + 2 h k
a* b* U12 ]
________________________________________________________________________
U11 U22 U33 U23 U13 U12
________________________________________________________________________
F(1) 76(1) 116(1) 97(1) -33(1) 28(1) 26(1)
O(1) 44(1) 51(1) 48(1) 8(1) 1(1) 11(1)
O(2) 59(1) 77(1) 41(1) 0(1) -4(1) 33(1)
N(1) 30(1) 39(1) 30(1) 1(1) 0(1) 0(1)
C(1) 31(1) 38(1) 38(1) 4(1) 6(1) -3(1)
C(2) 33(1) 55(1) 32(1) 3(1) 1(1) 5(1)
C(3) 33(1) 60(1) 32(1) -3(1) 1(1) -3(1)
C(4) 41(1) 41(1) 41(1) -4(1) 7(1) -5(1)
C(5) 50(1) 47(1) 48(1) -8(1) 13(1) 3(1)
C(6) 40(1) 52(1) 35(1) -4(1) 14(1) 0(1)
C(7) 46(1) 59(1) 36(1) 5(1) 14(1) 3(1)
C(8) 41(1) 77(1) 33(1) 4(1) 5(1) 6(1)
C(9) 41(1) 68(1) 34(1) 1(1) 11(1) -3(1)
C(10) 45(1) 106(2) 47(1) -8(1) 14(1) 9(1)
C(11) 43(1) 179(3) 55(1) -4(2) 15(1) 13(1)
C(12) 50(1) 196(3) 49(1) 3(2) 9(1) -36(2)
C(13) 83(2) 128(2) 57(1) -1(1) 10(1) -54(2)
C(14) 63(1) 80(1) 53(1) -1(1) 13(1) -23(1)
C(15) 31(1) 41(1) 31(1) 1(1) -3(1) 1(1)
C(16) 55(1) 49(1) 35(1) 5(1) 1(1) -11(1)
C(17) 72(1) 68(1) 31(1) 4(1) 4(1) -12(1)
C(18) 59(1) 65(1) 34(1) -8(1) -4(1) -5(1)
C(19) 56(1) 50(1) 47(1) -8(1) -1(1) -13(1)
C(20) 42(1) 46(1) 38(1) 1(1) 4(1) -8(1)
________________________________________________________________________
284
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x
10 3) for C20H16FNO2
________________________________________________________________________
x y z U(eq)
________________________________________________________________________
H(3) 2417 2512 3677 50
H(4) 1343 4707 3207 49
H(5A) 426 4235 4178 57
H(5B) -290 4154 3364 57
H(7A) 465 -1258 4335 55
H(8A) 2021 -469 4410 61
H(8B) 1744 1646 4761 61
H(11) -3123 2280 3881 110
H(12) -3529 -837 3327 118
H(13) -2405 -2980 3016 107
H(14) -849 -2034 3258 78
H(16) 1634 2039 930 56
H(17) 1500 255 -261 69
H(18) 851 -2948 -374 65
H(19) 343 -4428 702 62
H(20) 460 -2675 1894 51
________________________________________________________________________
285
Table 6. Torsion angles [°] for C20H16FNO2
________________________________________________________________
C(2)-N(1)-C(1)-O(1) -179.20(13)
C(15)-N(1)-C(1)-O(1) 5.4(2)
C(2)-N(1)-C(1)-C(4) -0.76(15)
C(15)-N(1)-C(1)-C(4) -176.20(11)
C(1)-N(1)-C(2)-O(2) 180.00(14)
C(15)-N(1)-C(2)-O(2) -4.5(2)
C(1)-N(1)-C(2)-C(3) 0.37(16)
C(15)-N(1)-C(2)-C(3) 175.89(12)
O(2)-C(2)-C(3)-C(4) -179.44(15)
N(1)-C(2)-C(3)-C(4) 0.17(15)
O(2)-C(2)-C(3)-C(8) -56.6(2)
N(1)-C(2)-C(3)-C(8) 122.99(12)
O(1)-C(1)-C(4)-C(3) 179.20(13)
N(1)-C(1)-C(4)-C(3) 0.82(14)
O(1)-C(1)-C(4)-C(5) 56.62(18)
N(1)-C(1)-C(4)-C(5) -121.75(12)
C(2)-C(3)-C(4)-C(1) -0.58(14)
C(8)-C(3)-C(4)-C(1) -121.08(13)
C(2)-C(3)-C(4)-C(5) 118.84(13)
C(8)-C(3)-C(4)-C(5) -1.66(17)
C(1)-C(4)-C(5)-C(6) 73.54(15)
C(3)-C(4)-C(5)-C(6) -43.42(17)
C(4)-C(5)-C(6)-C(7) 47.30(18)
C(4)-C(5)-C(6)-C(9) -131.34(14)
C(9)-C(6)-C(7)-C(8) 176.97(13)
C(5)-C(6)-C(7)-C(8) -1.7(2)
C(6)-C(7)-C(8)-C(3) -45.8(2)
C(2)-C(3)-C(8)-C(7) -72.57(16)
C(4)-C(3)-C(8)-C(7) 44.90(18)
C(7)-C(6)-C(9)-C(10) 136.89(17)
C(5)-C(6)-C(9)-C(10) -44.5(2)
C(7)-C(6)-C(9)-C(14) -42.4(2)
C(5)-C(6)-C(9)-C(14) 136.19(16)
C(14)-C(9)-C(10)-F(1) 176.64(16)
286
C(6)-C(9)-C(10)-F(1) -2.7(3)
C(14)-C(9)-C(10)-C(11) -0.9(3)
C(6)-C(9)-C(10)-C(11) 179.83(18)
F(1)-C(10)-C(11)-C(12) -176.6(2)
C(9)-C(10)-C(11)-C(12) 0.8(3)
C(10)-C(11)-C(12)-C(13) -0.4(4)
C(11)-C(12)-C(13)-C(14) 0.0(4)
C(12)-C(13)-C(14)-C(9) 0.0(3)
C(10)-C(9)-C(14)-C(13) 0.4(3)
C(6)-C(9)-C(14)-C(13) 179.75(17)
C(1)-N(1)-C(15)-C(20) -113.92(14)
C(2)-N(1)-C(15)-C(20) 71.11(17)
C(1)-N(1)-C(15)-C(16) 68.61(17)
C(2)-N(1)-C(15)-C(16) -106.36(16)
C(20)-C(15)-C(16)-C(17) 0.0(2)
N(1)-C(15)-C(16)-C(17) 177.46(13)
C(15)-C(16)-C(17)-C(18) 0.1(3)
C(16)-C(17)-C(18)-C(19) -0.3(3)
C(17)-C(18)-C(19)-C(20) 0.5(3)
C(16)-C(15)-C(20)-C(19) 0.2(2)
N(1)-C(15)-C(20)-C(19) -177.27(13)
C(18)-C(19)-C(20)-C(15) -0.4(2)
________________________________________________________________
287
Least-squares planes (x,y,z in crystal coordinates) and deviations from them
(* indicates atom used to define plane)
- 11.1333 (0.0035) x - 3.6499 (0.0026) y + 8.0309 (0.0088) z = 0.1892 (0.0027)
* 0.0050 (0.0008) O1
* 0.0037 (0.0009) O2
* -0.0009 (0.0010) N1
* -0.0082 (0.0011) C1
* -0.0019 (0.0012) C2
* -0.0017 (0.0010) C3
* 0.0039 (0.0010) C4
Rms deviation of fitted atoms = 0.0043
5.6878 (0.0121) x + 4.7735 (0.0037) y + 8.6114 (0.0164) z = 4.9636 (0.0044)
Angle to previous plane (with approximate esd) = 60.29 ( 0.06 )
* -0.0086 (0.0009) C3
* 0.0086 (0.0009) C4
* -0.0047 (0.0005) C5
* 0.0048 (0.0005) C8
Rms deviation of fitted atoms = 0.0070
- 3.3274 (0.0134) x + 2.0429 (0.0060) y + 16.3286 (0.0049) z = 6.6420 (0.0016)
Angle to previous plane (with approximate esd) = 48.37 ( 0.09 )
* 0.0035 (0.0004) C5
* -0.0074 (0.0009) C6
* 0.0075 (0.0009) C7
* -0.0036 (0.0004) C8
Rms deviation of fitted atoms = 0.0058
288
- 0.8359 (0.0128) x - 2.7850 (0.0036) y + 15.5270 (0.0050) z = 5.6824 (0.0038)
Angle to previous plane (with approximate esd) = 44.00 ( 0.05 )
* -0.0175 (0.0013) C9
* -0.0192 (0.0017) C10
* -0.0173 (0.0018) C11
* 0.0040 (0.0017) C12
* 0.0157 (0.0017) C13
* 0.0053 (0.0014) C14
* 0.0288 (0.0012) F1
Rms deviation of fitted atoms = 0.0173
12.7151 (0.0055) x - 2.6376 (0.0043) y + 2.5206 (0.0118) z = 1.7723 (0.0011)
Angle to previous plane (with approximate esd) = 67.27 ( 0.06 )
* -0.0004 (0.0010) C15
* 0.0007 (0.0011) C16
* 0.0005 (0.0012) C17
* -0.0021 (0.0013) C18
* 0.0025 (0.0012) C19
* -0.0012 (0.0010) C20
Rms deviation of fitted atoms = 0.0015
289
Selected Pictures and Plots
X-ray Crystals of Cross-Coupled Cycloadduct, 13.3.2e
290
Unit cell of 13.3.2e not showing Head-to-Tail packing
291
Space filled molecular model of 13.1.2a
292
SCHOLASTIC VITA
RAMAKRISHNA R. PIDAPARTHI
BORN: July 10; Subbareddy Palem (village), Andhra Pradesh, INDIA UNDERGRADUATE
STUDY: V. V. Pura College of Science& Arts (Bangalore University) Bangalore, Karnataka, INDIA B. Sc., Chemistry, 1990 GRADUATE STUDY: V. V. Pura College of Arts & Science (Bangalore University) Bangalore, Karnataka, INDIA P. G. D. S., with Honors, 1991 SCHOLASTIC AND PROFESSIONAL EXPERIENCE:
Research Assistant, Wake Forest University, 2004-2008 Teaching Assistant, Wake Forest University, 2002-2004 Production & Marketing Officer, Shaanshi Seritech Limited, INDIA, 1999-2001 Batch House & Production Supervisor, Shaanshi Seritech Limited, INDIA, 1998-1999 Junior Lecturer, Government College of Arts & Science, INDIA, 1994-1997 Junior Lecturer, S.C.V.S Junior College, INDIA, 1991-1993 HONORS AND AWARDS:
Alumni Student Travel Award, Wake Forest University, 2007
Reviewer, Panel for Membership Reviewing Committee (Sigma-Xi) PROFESSIONAL SOCIETIES:
Associate Member: American Chemical Society (ACS), Organic and Medicinal Chemistry Associate Member: American Association for the Advancement of Science (AAAS) Associate Member: The Scientific Research Society (Sigma-Xi) PEER-REVIEWED ARTICLES:
Pidaparthi, R. R.; Junker, C. S.; Welker, M. E.; Day, C. S. and Wright, M. W. (2010), ChemInform Abstract: Preparation of 2-Silicon-Substituted 1,3-Dienes and Their Diels-Alder/Cross-Coupling Reactions. ChemInform, 41: no. doi: 10.1002/chin.201012161
293
“Preparation of 2-Silicon-substituted 1,3-Dienes and their Diels-Alder/Cross-Coupling Reactions” Pidaparthi, R. R.; Junker, C. S.; Welker, M. E.; Day, C. S.; Wright, M. W. J. Org.
Chem. 2009, 74(21), 8290-8297 “ChemInform Abstract: Preparation of Siloxacyclopentene Containing 1,3-Dienes and Their Diels-Alder Reactions” 2008, DOI: 10.1002/chin.200807150 (review abstract) “Preparation of Siloxacyclopentene Containing-1,3-Dienes and Their Diels-Alder Reactions” Pidaparthi, R. R.; Welker, M. E. Tetrahedron Lett. 2007, 48(44), 7853-7856 “Preparation of 2-Trialkylsiloxy Substituted 1,3-Dienes and Their Diels-Alder/Cross-Coupling Reactions” Pidaparthi, R. R.; Welker, M. E.; Day, C. S.; Wright, M. W. Org. Lett. 2007, 9(9), 1623-1626 “[6+4] and [4+2] Cycloaddition Reactions of Cobaloxime 1,3-Dienyl Complexes and Tropones” Pidaparthi, R. R.; Welker, M. E.; Day, C. S. Organometallics 2006 25(4), 974-981
COMMERCIALIZED COMPOUNDS, PATENTS, PUBLISHED CONFERENCE PROCEEDINGS &
ABSTRACTS:
Starting from November 2008, the silyl dienes we prepared so far, two of them such as: Bis(1,2-benzenediolato)(1,3-butadien-2-yl)silicate (CAS# 937796-66-8) & 2,2’,2’’-Nitrilotris(ethanolato) (buta-1,3-dien-2-yl)silane (CAS#937796-65-7) are produced and marketed through STREM CHEMICALS under research chemicals category “Compounds and Compositions Containing Silicon and/or other Heteroatoms and/or
Metals and Methods of Making and using them” Pidaparthi, R. R.; Welker, M. E. International patent application (WO 2008/054718 A2) was approved by U. S. Patent & Trademark Office on 05/08/2008 “New Silicon Substituted Dienes and their Diels-Alder Cycloadducts as Polymerization
Monomers, Plasticizers, Curing and Coupling Agents.” Pidaparthi, R. R.; Welker, M. E. Provisional patent application (60/855,428) filed with U.S. Patent & Trademark Ofice on 11/20/2006
“Synthesis and Tandem Reactions of Main Group Element Boron, Aluminum and Silicon
Substituted 1,3-Dienes” Welker, M. E.; Pidaparthi, R. R.; De, S.; Crook, K. E.; Solano, J. Cope Scholar Award Symposium II, Greenville, SC, October 24-27, 2007 (Invited Talk) “Silyl Dienes and their Reactions in Consecutive Transmetalation/Diels-Alder/Cross-
Coupling Sequences” Pidaparthi, R. R.; Welker, M. E.; Day, C. S.; Wright, M. W. 40th National Organic Chemistry Symposium by American Chemical Society, Duke University, Durham, NC, June 3–7, 2007 (Presentation) “A Classical Approach Towards Transition-Metal Assisted One-Pot, Multi-component
Sequential/Tandem/Domino Reactions using Novel Silyl Dienes” Pidaparthi, R. R.;
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Welker, M. E. Day, C. S.; Wright, M. W. 7th Annual Graduate Student Research Day, Wake Forest University, Winston-Salem, NC, March 14, 2007 (Presentation) “Progressive Study in Developing One-Pot, Three Component Domino Reactions for
Stereoslective Synthesis of Cyclohexenes from Transmetalated (in-situ) Silyl Dienes” Pidaparthi, R. R.; Welker, M. E. 58th South-East Regional Meeting of the American Chemical Society, Augusta, GA, November 1– 4, 2006 (Oral) “Novel Synthesis of Air Stable, Moisture Resistant Silyl Dienes – Sequential/Tandem
Diels-Alder and Hiyama Coupling Reactions” Pidaparthi, R. R., Welker, M. E. 6th Annual Graduate Student Research Day, Wake Forest University, Winston-Salem, NC, March 24, 2006 (Presentation) “Cobalt Mediated Higher-Order [6+4] and Diels-Alder [4+2] Cycloaddition Reactions with
Substituted Tropones” Pidaparthi, R. R.; Welker, M. E. 56th South-East Regional Meeting of the American Chemical Society, Research Triangle Park, NC, November 10–13, 2004
(Presentation) “Cobalt-Mediated Cycloaddition Reactions with Tropones” Pidaparthi, R. R.; Welker, M. E.; Wright, M. W. 4th Annual Graduate Student Research Day, Wake Forest University, Winston-Salem, NC, March 26, 2004 (Presentation)
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Biography
Ramakrishna Reddy, Pidaparthi was born July 10 in a small hamlet, Subbareddypalem
having a pouplation of nearly 300 people. This small village is located in south-eastern part of
Andhra Pradesh (state), India. He did his undergraduate work at V.V.Puram College of Arts &
Science, Bangalore, and received a degree in Bachelor of Science in 1990 and continued for a
diploma in graduate study in the same school. He graduated in 1991 with Honors and started
career as a lecturer (high school teacher) in S.C.V.S Jr. College and Government College of Arts &
Science (GAS), Sattenapalli from 1991 to 1997. Later he moved to an agri-based industry seeking
industrial exposure from 1998 to 2001. After gaining few years of industrial experience in
various levels, he was accepted as graduate student in Wake Forest University, NC to pursue his
Ph. D. degree in 2002. He began to work on his Ph. D. in Chemistry under the supervison of
Professor Mark E. Welker with combined interest in metal-mediated organocatalysis and
advanced research in Diels-Alder and Cross-Coupling reactions. At present, he is working as a
Post-Doctoral Research Chemist at RTI, International and managing a project involving the
synthesis of small molecules, haptens that are conjugated to a variety of proteins in order to
elucidate monoclonal antibodies to treat drug addiction and dependency. Also, these gained
experience is being extended in developing antigens and vaccines for treating drug and nicotine
addiction studies.