toc 18 january 2011; 14:44:2€¦ · handbook of green chemistry - green catalysis 3 volume set...

TOC 18 January 2011; 14:44:2

Privileged Chiral Ligands

and Catalysts

Edited by

Qi-Lin Zhou

FFIRS 20 January 2011; 12:39:5

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Edited by Qi-Lin Zhou

Privileged Chiral Ligands and Catalysts

WILEY-VCH Verlag GmbH & Co. KGaA


The Editor

Prof. Qi-Lin Zhou

Nankai University

Institute of Elemento-Organic Chemistry

94 Weijin Road

Tianjin 300071

China

& All books published by Wiley-VCH are carefully

produced. Nevertheless, authors, editors, and

publisher do not warrant the information

contained in these books, including this book, to

be free of errors. Readers are advised to keep in

mind that statements, data, illustrations,

procedural details or other items may

inadvertently be inaccurate.

Library of Congress Card No.: applied for

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A catalogue record for this book is available

from the British Library.

Bibliographic information published by the

Deutsche Nationalbibliothek

The Deutsche Nationalbibliothek lists this

publication in the Deutsche Nationalbibliografie;

detailed bibliographic data are available on the

Internet at ohttp://dnb.d-nb.deW.

& 2011 Wiley-VCH Verlag & Co. KGaA,

Boschstr. 12, 69469 Weinheim, Germany

All rights reserved (including those of translation

into other languages). No part of this book may be

reproduced in any form – by photoprinting,

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ISBN: 978-3-527-32704-1


http://dnb.d-nb.de

Contents

Preface XVList of Contributors XIX

1 BINAP 1Takeshi Ohkuma and Nobuhito Kurono

1.1 Introduction: Structural Consideration 11.2 Hydrogenation of Olefins 31.3 Hydrogenation of Ketones 61.3.1 Functionalized Ketones 61.3.2 Simple Ketones 91.4 Isomerization of Allylamines and Allylalcohols 131.5 Hydroboration, Hydrosilylation, Hydroacylation,

and Hydroamination 141.6 Allylic Alkylation 181.7 Heck Reaction 181.7.1 Intramolecular Reaction 181.7.2 Intermolecular Reaction 191.8 Aldol and Mannich-Type Reactions 211.8.1 Aldol Reaction 211.8.2 Mannich-Type Reaction 231.9 Nucleophilic Additions to Carbonyl and Imino

Compounds 241.9.1 Allylation 241.9.2 Alkenylation and Arylation 251.9.3 Dienylation 261.9.4 Cyanation 271.10 a-Substitution Reactions of Carbonyl Compounds 281.10.1 Fluorination and Amination 281.10.2 Arylation and Orthoester Alkylation 291.11 Michael-Type Reactions 30

Privileged Chiral Ligands and Catalysts. Edited by Qi-Lin ZhouCopyright r 2011 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimISBN: 978-3-527-32704-1

| V

TOC 18 January 2011; 14:44:2

1.11.1 Michael Reaction 301.11.2 Aza-Michael Reaction 321.12 Conjugate Additions Using Organoboron and Grignard

Reagents 321.13 Diels–Alder Reaction 351.14 Ene Reaction 381.15 Cyclization 381.15.1 Intramolecular Reactions of Enynes 381.15.2 [3þ 2] and [5þ 2] Cycloaddition Reactions 391.15.3 [2þ 2þ 2] Cycloaddition Reactions 421.15.4 Pauson–Khand Type Reactions 431.16 Ring-Opening Reactions 451.17 Concluding Remarks 45

2 Bisphosphacycles — From DuPhos and BPE to a Diverse Setof Broadly Applied Ligands 55Weicheng Zhang and Xumu Zhang

2.1 Introduction 552.2 Development of Bisphosphacycle Ligands 552.2.1 Structural Features of DuPhos and BPE 552.2.2 Strategies of Ligand Design 582.3 Applications of Bisphosphacycle Ligands 652.3.1 Asymmetric Hydrogenation 652.3.2 Asymmetric Hydroformylation 752.3.3 Asymmetric Hydrosilylation 772.3.4 Asymmetric Hydroacylation 772.3.5 Asymmetric Cycloisomerization, Cycloaddition, and

Cyclization 782.3.6 Asymmetric Phosphination 812.3.7 Asymmetric Nucleophilic Addition to Ketones and

Ketimines 822.3.8 Asymmetric Conjugate Addition 852.3.9 Miscellaneous Reactions 852.4 Concluding Remarks 87

3 Josiphos Ligands: From Discovery to TechnicalApplications 93Hans-Ulrich Blaser, Benoıt Pugin, Felix Spindler, Esteban Mejıa, and

Antonio Togni

3.1 Introduction and Background 933.2 Discovery and Development of the Josiphos Ligand

Family 943.3 Why Are Josiphos Ligands So Effective? 97

VI | Contents

TOC 18 January 2011; 14:44:2

3.3.1 General Considerations 973.3.2 Structural Aspects of Transition Metal Complexes Containing

Josiphos and Josiphos-Like Ligands 993.4 Catalytic Profile of the Josiphos Ligand Family 1043.4.1 Enantioselective Reductions of C¼C, C¼O and C¼N

Bonds 1043.4.1.1 Enantioselective Hydrogenation of C¼C Bonds 1043.4.1.2 Copper-Catalyzed Reduction of Activated C¼C bonds with

PMHS (Conjugate Reduction) 1103.4.1.3 Enantioselective Hydrogenation of C¼O Bonds 1113.4.1.4 Enantioselective Hydrogenation of C¼N Bonds 1143.4.2 Enantioselective Hydrofunctionalizations 1183.4.2.1 Hydroboration 1183.4.2.2 Hydroamination and Hydrophosphonation 1193.4.2.3 Hydrocarboxylation 1203.4.3 Enantioselective C–C Bond Forming Reactions 1203.4.3.1 Allylic Alkylation 1203.4.3.2 Michael Addition 1213.4.3.3 Heck Reaction 1223.4.3.4 Miscellaneous C–C Reactions 1233.4.4 Miscellaneous Enantioselective Reactions 1253.4.4.1 Isomerization of Allylamines 1253.4.4.2 Ring-Opening of Oxabicycles 1253.4.4.3 Allylic Substitution 1263.4.5 Application in Non-Enantioselective Reactions 1273.5 Concluding Remarks 127

4 Chiral Spiro Ligands 137Shou-Fei Zhu and Qi-Lin Zhou

4.1 Introduction 1374.2 Preparation of Chiral Spiro Ligands 1394.3 Asymmetric Hydrogenation 1444.3.1 Hydrogenation of Functionalized Olefins 1444.3.1.1 Hydrogenation of Enamides 1444.3.1.2 Hydrogenation of Enamines 1464.3.1.3 Hydrogenation of a,b-Unsaturated Acids 1464.3.2 Hydrogenation of Ketones and Aldehydes 1514.3.2.1 Hydrogenation of Simple Ketones 1514.3.2.2 Hydrogenation of Racemic 2-Substituted Ketones via DKR 1514.3.2.3 DKR Hydrogenation of Racemic 2-Substituted Aldehydes 1534.3.3 Hydrogenation of Imines 1544.3.4 Hydrogenation of 2-Substituted Quinolines 1544.4 Asymmetric Carbon–Carbon Bond Forming Reaction 155

Contents | VII

TOC 18 January 2011; 14:44:2

4.4.1 Rhodium-Catalyzed Arylation of Carbonyl Compounds andImines 155

4.4.2 Palladium-Catalyzed Umpolung Allylation of Aldehydes 1584.4.3 Copper-Catalyzed Conjugate Addition Reaction 1584.4.4 Copper-Catalyzed Ring-Opening Reaction with Grignard

Reagents 1584.4.5 Nickel-Catalyzed Three-Component Coupling Reaction 1594.4.6 Nickel-Catalyzed Hydrovinylation Reaction 1614.4.7 Rhodium-Catalyzed Hydrosilylation/Cyclization Reaction 1614.4.8 Palladium-Catalyzed Asymmetric Oxidative Cyclization 1624.4.9 Gold-Catalyzed Ring Expanding Cycloisomerization 1634.5 Asymmetric Carbon–Heteroatom Bond Forming

Reaction 1634.5.1 Palladium-Catalyzed Hydrosilylation 1634.5.2 Palladium-Catalyzed Wacker-Type Oxidative Cyclization

Reaction 1634.5.3 Copper-Catalyzed Carbene Insertion into X–H Bonds 1644.5.4 Allene-Based Allylic Cyclization Reactions 1664.6 Conclusion 167

5 Chiral Bisoxazoline Ligands 171Levi M. Stanley and Mukund P. Sibi

5.1 Introduction 1715.2 Enantioselective Carbon–Carbon Bond Formation 1765.2.1 Addition of Carbon Nucleophiles to C¼O and C¼N Bonds 1765.2.1.1 Aldol Reactions 1765.2.1.2 Mannich-Type Reactions 1775.2.1.3 Nitroaldol (Henry) Reactions 1795.2.1.4 Nitro-Mannich (Aza-Henry) Reactions 1815.2.1.5 Addition of Activated Carbon Nucleophiles to Carbonyl

Electrophiles 1825.2.1.6 Addition of Activated Carbon Nucleophiles to Imines 1835.2.1.7 Ene Reactions 1845.2.1.8 Friedel–Crafts Reactions of Aromatic Compounds with C¼O and

C¼N Bonds 1845.2.2 1,4-Addition of Carbon Nucleophiles to a,b-Unsaturated

Acceptors 1865.2.3 Reactions of Radicals Alpha to Carbonyls 1905.2.4 Cyclization Reactions 1915.2.5 Rearrangement Reactions 1915.3 Enantioselective Carbon–Heteroatom Bond Formation 1935.3.1 1,4-Addition of Heteroatom Nucleophiles to a,b-Unsaturated

Acceptors 1935.3.1.1 1,4-Addition of Nitrogen Nucleophiles 193

VIII | Contents

TOC 18 January 2011; 14:44:2

5.3.1.2 1,4-Addition of Sulfur and Oxygen Nucleophiles 1955.3.1.3 1,4-Addition of Boron Nucleophiles 1955.3.2 Allylic Functionalization Reactions 1965.3.3 a-Heteroatom Functionalization of Carbonyl Compounds 1965.3.3.1 Amination 1965.3.3.2 Oxygenation 1975.3.3.3 Halogenation 1975.3.4 X–H Insertion Reactions (X ¼ O, N, S) 1985.3.5 Cyclization Reactions 1995.3.5.1 Carbonylative Cyclization 1995.3.5.2 Wacker-Type Cyclizations 1995.3.5.3 Hydroamination 2015.3.6 Kinetic Resolution and Desymmetrization Reactions 2015.3.6.1 Kinetic Resolution 2015.3.6.2 Desymmetrization 2015.4 Enantioselective Cycloaddition Reactions 2025.4.1 Carbo-Diels–Alder Cycloadditions 2025.4.2 Hetero-Diels–Alder Cycloadditions 2045.4.3 Cyclopropanations 2055.4.4 Aziridination 2085.4.5 1,3-Dipolar Cycloadditions 2095.4.6 Additional Cycloaddition Reactions 2115.5 Conclusions 212

6 PHOX Ligands 221Cory C. Bausch and Andreas Pfaltz

6.1 Introduction 2216.2 Synthesis of PHOX Ligands 2226.3 Nucleophilic Allylic Substitution 2246.3.1 Palladium-Catalyzed Allylic Substitution 2246.3.2 Tungsten- and Iridium-Catalyzed Allylic Substitution 2296.3.3 Allylic Substitution in Total Synthesis 2306.4 Decarboxylative Tsuji Allylations 2316.4.1 Method Development 2316.4.2 Application to Fluorinated Derivatives 2346.4.3 Applications in Total Synthesis 2356.5 Heck Reaction 2376.5.1 Intermolecular Heck Reaction 2376.5.2 Intramolecular Heck Reaction 2386.6 Hydrogenation 2406.6.1 Hydrogenation of Imines 2406.6.2 Hydrogenation of Trisubstituted Olefins 2406.6.3 Hydrogenation of Tetrasubstituted Olefins 2436.6.4 Hydrogenation of Vinyl Phosphonates 243

Contents | IX

TOC 18 January 2011; 14:44:2

6.6.5 Hydrogenation of a,b-Unsaturated Ketones 2446.6.6 Hydrogenation of Ketones 2446.6.7 Transfer Hydrogenation of Ketones 2466.7 Cycloadditions 2466.7.1 [3þ 2] Cycloadditions 2466.7.2 Diels–Alder Reactions 2476.8 Miscellaneous Reactions 2486.8.1 Hydrosilylations 2486.8.2 Pauson–Khand Reaction 2486.8.3 Decarboxylative Protonation 2496.8.4 Sigmatropic Rearrangements 2506.8.5 Desymmetrization Reactions 2516.8.6 Asymmetric Arylations 2536.9 Conclusion 253

7 Chiral Salen Complexes 257Wen-Zhen Zhang and Xiao-Bing Lu

7.1 Introduction 2577.2 Synthesis of Chiral Salen Complexes 2577.3 Structural Properties of Chiral Salen Complexes 2597.4 Asymmetric Reactions Catalyzed by Chiral Salen

Complexes 2627.4.1 Asymmetric Epoxidation 2627.4.2 Asymmetric Ring-Opening of Epoxides 2667.4.2.1 Desymmetrization of Meso-Epoxides 2667.4.2.2 Kinetic Resolution of Racemic Epoxides 2697.4.2.3 Enantioselective Addition of Carbon Dioxide to Propylene

Oxide 2717.4.2.4 Asymmetric Alternating Copolymerization of Racemic Epoxides

and Carbon Dioxide 2727.4.2.5 Enantioselective Homopolymerization of Epoxides 2737.4.3 Asymmetric Cyclopropanation 2747.4.4 Asymmetric Conjugate Addition Reaction 2777.4.5 Asymmetric Diels–Alder Reaction 2817.4.6 Asymmetric Cyanohydrin Synthesis 2847.4.7 Miscellaneous Reactions 2877.5 Conclusion and Outlook 289

8 BINOL 295Masakatsu Shibasaki and Shigeki Matsunaga

8.1 Introduction 2958.2 Applications in Reduction and Oxidation 2968.3 Metal/BINOL Chiral Lewis Acid Catalysts in Asymmetric

C–C Bond Forming Reactions 300

X | Contents

TOC 18 January 2011; 14:44:2

8.3.1 Group IV Metal/BINOL Lewis Acid Catalysts 3008.3.2 Group XIII Metal/BINOL Lewis Acid Catalysts 3048.3.3 Rare Earth Metal/BINOL Lewis Acid Catalysts 3078.4 Acid/Base Bifunctional Metal/BINOL Catalysts 3088.4.1 Rare Earth Metal/Alkali Metal/BINOL Catalysts 3088.4.2 Group XIII Metal/Alkali Metal/BINOL Catalysts 3128.4.3 Other Metal/BINOL Complexes as Acid/Base Bifunctional

Catalysts 3168.4.4 Lewis Acid/Lewis Base Bifunctional Aluminium-Catalyst 3218.5 BINOL in Organocatalysis 3248.6 Summary 329

9 TADDOLate Ligands 333Helene Pellissier

9.1 Introduction 3339.2 Nucleophilic Additions to C¼O Double Bonds 3349.2.1 Organozinc Additions to Aldehydes 3349.2.2 Allylations 3359.2.3 Aldol-Type Reactions 3369.2.4 Miscellaneous Reactions 3389.3 Nucleophilic Conjugate Additions to Electron-Deficient

C¼C Double Bonds 3399.4 Nucleophilic Substitutions 3429.4.1 Allylic Substitutions 3429.4.2 a-Halogenations of Carbonyl Compounds 3449.4.3 Miscellaneous Substitutions 3459.5 Cycloaddition Reactions 3459.5.1 Diels�Alder reactions 3469.5.2 Hetero-Diels–Alder Reactions 3479.5.3 Miscellaneous Cycloadditions 3489.6 Oxidation and Reduction Reactions 3499.7 Miscellaneous Reactions 3519.8 Conclusions 354

10 Cinchona Alkaloids 361Hongming Li, Yonggang Chen and Deng Li

10.1 Introduction 36110.2 Metal Catalysis 36310.3 Phase-Transfer Catalysis 36710.3.1 Asymmetric Alkylations 36710.3.2 Asymmetric Conjugate Additions 36810.3.3 Asymmetric Aldol Reactions 36810.3.4 Examples of Recent Applications 36910.4 Nucleophilic Catalysis 370

Contents | XI

TOC 18 January 2011; 14:44:2

10.4.1 Asymmetric Reactions with Ketenes 37010.4.2 Asymmetric Morita–Baylis–Hillman Reactions 37310.4.3 Asymmetric Cyanation of Simple Ketones 37410.4.4 Recent Applications of Nucleophilic Catalysis by Cinchona

Alkaloids 37510.4.4.1 Asymmetric Conjugate Additions 37510.4.4.2 Asymmetric Electrophilic Halogenations of Olefins 37610.5 Base Catalysis 37710.5.1 Asymmetric Alcoholysis of Cyclic Anhydrides 37710.5.2 Conjugate Additions 38010.5.3 Asymmetric Mannich and Aldol Reactions 38110.6 Cooperative and Multifunctional Catalysis 38210.6.1 Acid–Base Cooperative Catalysis 38210.6.1.1 Asymmetric Conjugate Additions 38210.6.1.2 Asymmetric 1,2-Additions to Carbonyls 38610.6.1.3 Asymmetric 1,2-Additions to Imines 39010.6.1.4 Asymmetric Friedel–Crafts Reactions 39110.6.1.5 Asymmetric Diels–Alder Reactions 39310.6.1.6 Asymmetric Fragmentation 39410.6.2 Base–Iminium Cooperative Catalysis 39610.6.2.1 Asymmetric Conjugate Additions 39610.6.2.2 Asymmetric Fridel–Crafts Additions 39810.6.2.3 Asymmetric Diels–Alder Reactions 39910.6.2.4 Semipinacol-Type 1,2-Carbon Migration 39910.6.3 Multifunctional Cooperative Catalysis 40010.6.3.1 Tandem Conjugate Addition–Protonation Reactions 40010.6.3.2 Catalytic Asymmetric Peroxidations 40010.7 Conclusion 404

11 Proline Derivatives 409Shilei Zhang and Wei Wang

11.1 Introduction 40911.2 Proline as Organocatalyst 41011.2.1 Aldol Reactions 41011.2.1.1 Intermolecular Aldol Reactions 41011.2.1.2 Intramolecular Aldol Reactions 41211.2.1.3 Synthesis of Carbohydrates by Proline-Catalyzed Aldol

Reactions 41311.2.2 Mannich Reactions Catalyzed by Proline 41411.2.3 Michael Addition Reactions Catalyzed by Proline 41511.2.4 Morita–Baylis–Hillman (MBH) Reactions Catalyzed by

Proline 41611.2.5 a-Amination, a-Aminoxylation, and a-Alkylation of Carbonyl

Compounds Catalyzed by Proline 417

XII | Contents

TOC 18 January 2011; 14:44:2

11.2.6 Cascade/One-Pot Reactions Catalyzed by Proline 41811.3 Proline Analogs as Organocatalysts 41911.3.1 4-Hydroxyproline as Organocatalyst 41911.3.2 Other Proline Analogs as Organocatalysts 42111.4 5-Pyrrolidin-2-yltetrazole as Organocatalyst 42211.5 Pyrrolidine-Based Sulfonamides as Organocatalysts 42411.6 Pyrrolidine-Based Amides as Organocatalysts 42511.7 Pyrrolidine Diamine Catalysts 42711.8 Diarylprolinols or Diarylprolinol Ether Catalysts 42911.8.1 Aldol Reactions, Mannich Reactions, and Other

a-Functionalizations of Aldehydes Catalyzed byDiarylprolinols or Diarylprolinol Silyl Ethers 429

11.8.2 Michael Addition Reactions Catalyzed by Diarylprolinols orDiarylprolinol Silyl Ethers. 430

11.8.2.1 Michael Additions through an Enamine Pathway 43011.8.2.2 Michael Additions through an Iminium Mechanism 43011.8.3 Cycloaddition Reactions Catalyzed by Diarylprolinols or

Diarylprolinol Silyl Ethers 43311.8.4 Cascade Reactions Catalyzed by Diarylprolinol Silyl Ethers 43511.8.4.1 Three-Membered Rings Formed by a [1þ 2] Strategy 43511.8.4.2 Five-Membered Rings Formed by a [3þ 2] Strategy 43611.8.4.3 Six-Membered Rings Formed by a [4þ 2] Strategy 43711.8.4.4 Six-Membered Rings Formed by a [3þ 3] Strategy 43711.8.4.5 Six-Membered Rings Formed by a [2þ 2þ 2] Strategy 43811.8.4.6 Other Cascade Reactions 43911.9 Concluding Remarks 439

Index 447

Contents | XIII

TOC 18 January 2011; 14:44:2

TOC 18 January 2011; 14:44:2

Preface

Catalytic asymmetric synthesis has been one of the most active research areas in

modern chemistry. Asymmetric catalyses with enzymes, chiral metal complexes,

and chiral organic molecules have emerged as successful and powerful tools in

asymmetric synthesis. Among the three catalytic asymmetric processes, artificial

metal complex catalysis and organocatalysis have only a very short history

compared to traditional biocatalysis but are now a predominant part of asymmetric

synthesis in both research and application. The development of efficient synthetic

chiral catalysts, including chiral metal complex catalysts modified with various

chiral ligands and chiral organo-molecule catalysts, is at the center of research in

asymmetric catalysis. Although numerous chiral ligands as well as chiral catalysts

have been reported in past decades, only a handful of them, rooted in a very few

core structures, can be regarded as truly successful in demonstrating proficiency

in various mechanistically unrelated reactions. Researchers have designated chiral

catalysts showing good enantioselectivity over a wide range of different reactions

as “privileged chiral catalysts,” a term coined by Jacobsen. The essential feature

that makes a catalyst “privileged” is its scaffold (core structure). To understand the

relationship between the structure of a “privileged” catalyst and its catalytic

features in reactions is the key to opening the door to designing more efficient

catalysts. Furthermore, a deep insight into the structural characteristics of the

most successful catalysts so far reported will facilitate the selection of appropriate

catalysts in developing new asymmetric processes. However, available books on

asymmetric synthesis have focused predominantly on asymmetric reactions,

making it difficult to perceive the suite of chiral catalysts in terms of structural

characteristics and catalytic abilities. This book, Privileged Chiral Ligands andCatalysts, tells the stories of these ligands and catalysts from the core structure

point of view, a rarity in previous books. This book is a timely overview of a few

popularly used chiral ligands and catalysts, focused on their structural aspects and

the relationship between the structure of catalysts and their success in catalytic

operations.

It is not the goal, and it would be an almost impossible undertaking, to provide a

comprehensive book on chiral ligands and catalysts. To illustrate clearly the key

points of “privileged” chiral ligands and catalysts in a 400-page book we have se-

lected eleven ligands and catalysts as examples to discuss in detail, namely,


| XV

fpref 18 January 2011; 11:31:44

BINAP, DuPhos, Josiphos, spiro ligands, BOX, PHOX, Salen complexes, BINOL,

TADDOL, cinchona alkaloids, and proline, rather than examining all of the high-

profile candidates. Among the eleven, BINAP, DuPhos, Josiphos, spiro ligands,

BOX, and PHOX are chiral ligands in metal catalysts; Salen complexes are chiral

metal catalysts, and cinchona alkaloids and proline are generally used as

organocatalysts. BINOL and TADDOL were used as chiral ligands in Lewis acid

catalysts in earlier studies but recently they have also been used as organocatalysts

in various reactions. The editor, based solely on personal taste, has sought to ar-

range the presentation of the eleven ligands or catalysts by starting with ligands,

then addressing metal catalysts and organocatalysts. Although the selection is

subjective we believe that the important ligands and catalysts in the field of

asymmetric synthesis are included and that the general aspects of ligand and

catalyst design will thus be fully exhibited through these eleven examples.

The eleven selected ligands or catalysts are independent of each other and so, as

a result, each chapter in this book provides an individual overview of each one.

Although the authors responsible for each chapter were given sufficient freedom

to organize their material, we encouraged them to provide a short discussion of the

family of ligands or catalysts to which the individual ligand or catalyst belongs. It

is beneficial to readers to see the full spectrum of the ligands or catalysts rooted

on the same scaffolds. Each chapter also emphasizes the chiral-inducing models

of metal catalysts or organocatalysts to illustrate the transfer of chirality from

catalysts to substrates in different reactions. The most successful applications,

X

X PP

Me

Me

Me

Me

DuPhos

O

O

Me

Me

OH

OH

Ph

Ph

Ph

Ph

TADDOL

N N

OO

Me Me

tButBu

N N

tBu

tBu tBu

tBuOOM

HH

Salen complexes

N

OMe

OH

N

Cinchona alkaloid

XX

Spiro ligands

Fe

Me

PCy2

PPh2

Josiphos

BOX

N

O

iPr

PPh2

PHOX

NH

COOH

Proline

X � OH BINOL

X � PPh2 BINAP

XVI | Preface

fpref 18 January 2011; 11:31:44

especially the latest identified reactions of these ligands or catalysts, have been

described to support their designation as “privileged” catalytic properties. In

contrast, well-known classic applications are discussed only briefly.

The editor believes that the authors have described the most important features

of these specific ligands or catalysts discussed in this book. The reader can find the

design principle of the chiral ligands and catalysts readily in each chapter. Because

many common principles have been considered during the development of the

most successful ligands or catalysts, some overlap of these principles inevitably

occurs among the chapters. For instance, the features of high chemical robustness

and ease of modification can be found in all eleven selected ligands or catalysts.

Further, it is generally accepted that the high scaffold rigidity of the ligand or

catalyst plays a crucial role in making it “privileged.” Accordingly, the reader may

readily notice that almost all of the successful ligands or catalysts contain five- or

six-membered rings. In addition to the structural properties of each ligand or

catalyst, an easily available starting material is also important. At least three

selected ligands and catalysts – proline, cinchona alkaloids, and TADDOL – are

derived directly from a “chiral pool.” The chiral moiety of the ligands BOX

and PHOX are chiral amino alcohols, derived from natural amino acids. The

coordinating atom is another important aspect of ligand design, and the most

successful ligands all have phosphorus or nitrogen as the coordinating atom. In

addition, the dentate number of chiral ligands and the chelating ring size of cat-

alysts are crucial features for obtaining satisfactory chiral induction.

It is our hope that the new descriptive model in this book will lead readers

to constructive thinking about what makes chiral catalysts “privileged” and

encourage more creative work for the development of “privileged ligands

and catalysts.” If this book is helpful to our colleagues in the chemistry community

in their design of chiral ligands or catalysts, selection of appropriate catalysts in

their chiral synthesis, or other aspects of their research we believe our goal will

have been met.

I am deeply indebted to all chapter authors for their significant contributions to

the book. I am grateful to Dr. Elke Maase of Wiley-VCH, who initiated the project

of editing this book, and to Lesley Belfit for her support during the editing process.

I also thank my colleague Dr. Shou-Fei Zhu for his constructive suggestions in

editing this book.

Qi-Lin ZhouNankai University

Tianjin, China

Preface | XVII

fpref 18 January 2011; 11:31:44

fpref 18 January 2011; 11:31:44

List of Contributors

Cory Bausch

University of Basel

Department of Chemistry

St. Johanns-Ring 19

4056 Basel

Switzerland

Hans-Ulrich Blaser

Solvias AG

P.O. Box

4002 Basel

Switzerland

Yonggang Chen

Brandeis University


415 South St., Waltham

MA 024543

USA

Li Deng

Brandeis University



MA 024543

USA

Nobuhito Kurono

Hokkaido University, Graduate School

of Engineering

Division of Chemical Process

Engineering, Laboratory of Organic

Synthesis

Sapporo 060- 8628

Japan

Hongming Li

Brandeis University



MA 024543

USA

Xiao-Bing Lu

Dalian University of Technology

State Key Laboratory of Fine

Chemicals

No. 2 Linggong Road

Dalian

Liaoning 116024

China


| XIX

flast 21 January 2011; 9:29:48

Shigeki Matsunaga

The University of Tokyo

Graduate School of Pharmaceutical

Sciences

Tokyo 113-0033

Japan

Esteban Mejıa

ETH Zurich

Laboratorium fur Anorganische Chemie

Wolfgang-Pauli-Str. 10

8093 Zurich

Switzerland

Takeshi Ohkuma

Hokkaido University, Graduate School

of Engineering

Division of Chemical Process

Engineering, Laboratory of Organic

Synthesis

Sapporo 060- 8628

Japan

Helene Pellissier

Universite Paul Cezanne –

Aix-Marseille III

Institut Sciences Moleculaires de

Marseille

Avenue Esc. Normandie-Niemen

13397 Marseille

France

Andreas Pfaltz

University of Basel


St. Johanns-Ring 19

4056 Basel

Switzerland

Benoıt Pugin

Solvias AG

P.O. Box

4002 Basel

Switzerland

Masakatsu Shibasaki

The University of Tokyo

Graduate School of Pharmaceutical

Sciences

Tokyo 113-0033

Japan

Mukund P. Sibi

North Dakota State University

Department of Chemistry and

Molecular Biology

1231 Albrecht Boulevard

Fargo

USA

Felix Spindler

Solvias AG

P.O. Box

4002 Basel

Switzerland

Levi M. Stanley

University of Illinois at

Urbana-Champaign


Urbana

USA

Antonio Togni

ETH Zurich

Laboratorium fur Anorganische Chemie

Wolfgang-Pauli-Str. 10

8093 Zurich

Switzerland

XX |List of Contributors


Wei Wang

University of New Mexico


Chemical Biology

Albuquerque

NM 87131-0001

USA

and

Chinese Academy of Sciences

Shanghai Institute of Materia Medica

Shanghai 201203

China

Shilei Zhang

University of New Mexico


Chemical Biology

Albuquerque

NM 87131-0001

USA

Weicheng Zhang

Nankai University

College of Pharmacy

94 Weijin Road

Tianjin 300071

China

Wen-Zhen Zhang

Dalian University of Technology

State Key Laboratory of Fine

Chemicals

No. 2 Linggong Road

Dalian

Liaoning 116024

China

Xumu Zhang

Rutgers, The State University of

New Jersey


Chemical Biology

610 Taylor Road

Piscataway

NJ 08854

USA

Qi-Lin Zhou

Nankai University

Institute of Elemento-organic

Chemistry

94 Weijin Road

Tianjin 300071

China

Shou-Fei Zhu

Nankai University

Institute of Elemento-organic

Chemistry

94 Weijin Road

Tianjin 300071

China

List of Contributors | XXI


1

BINAPTakeshi Ohkuma and Nobuhito Kurono

1.1

Introduction: Structural Consideration

BINAP (2,2u-diphenylphosphino-1,1u-binaphthyl), which was devised by Ryoji

Noyori (winner of the Nobel Prize in Chemistry 2001), is typical among chiral

diphosphine ligands [1–3]. BINAP chemistry has contributed notably the devel-

opment of the field of asymmetric catalysis [1, 4]. This ligand with transition

metallic elements forms C2-symmetric chelate complexes. Figure 1.1 indicates the

chiral structure created by an (R)-BINAP–transition metal complex. The naph-

thalene rings of BINAP are omitted in the side view (right-hand side) for clarity. As

illustrated in the top view, the axial-chirality information of the binaphthyl back-

bone is transferred through the P-phenyl rings to the four coordination sites

shown by & and ’. The coordination sites & placed in the P1–M–P2 plane are

sterically influenced by the “equatorial” phenyl rings, whereas the out-of-plane

coordination sites, ’, are affected by the “axial” phenyl groups (side view). Con-

sequently, the two kinds of quadrant of the chiral structure (first and third versus

second and forth in the side view) are clearly discriminated spatially, where the

second and fourth quadrants are sterically crowded, while the first and third ones

are open for approach of substrates and reagents. This chiral structure realizes

excellent enantiodifferentiation in various asymmetric catalytic reactions. The

flexibility of the binaphthyl backbone appears to enable a wide scope of substrate.

The great success of BINAP chemistry has encouraged researchers to develop

BINAP derivatives and related chiral biaryl diphosphines [5]. Figure 1.2 illustrates

representative examples. As shown in Figure 1.1, substitution manner of P-arylrings of BINAP ligands obviously affects the chiral structure of metal complexes.

TolBINAP, which has P-4-tolyl groups, shows similar enantioselective features to

those of BINAP, although the solubility of the metal complexes in organic solvents

is increased [6]. XylBINAP and DTBM-BINAP bearing 3,5-dialkyl groups on the

P-phenyl rings give better enantioselectivity than that with the original ligand in

some cases [6]. The bulkier P-aryl groups seem to make the contrast of congest-

ion in the chiral structure clearer. Diphosphines with a relatively small P1–M–P2

angle in the complexes, that is, MeO-BIPHEP [7], SEGPHOS [8], SYNPHOS


| 1

CH001 18 January 2011; 14:52:17

axeq

ax

eqP2P1

ax

ax

eqeq

top view side view

� coordination site in the P1�M�P2 plane

� coordination site out of the P1�M�P2 plane

Ph2

Ph2

M

P

P

(R)-BINAP

13

M

M � metallic element, ax � axial, eq � equatorial

24

Figure 1.1 Molecular models of an (R)-BINAP–transition metal complex.

PAr2

PAr2

PPh2

PPh2

PPh2

PPh2

R

R

PPh2

PPh2

O

O

O

O

PPh2

PPh2

O

O

O

OPPh2

PPh2

O

O

(CH2)n

X

X

X

X

PPh2

PPh2

N

N

CH3O

CH3O

OCH3

OCH3

S

S

PPh2

PPh2

BINAP: Ar � C6H5

TolBINAP: Ar � 4-CH3C6H4

XylBINAP: Ar � 3,5-(CH3)2C6H3

DTB-BINAP: Ar � 3,5-(t-C4H9)2C6H3

DTBM-BINAP: Ar � 3,5-(t-C4H9)2-4-CH3OC6H2

H8-BINAP BIPHEMP: R � CH3, X � H

MeO-BIPHEP: R � CH3O, X � H

Cl, MeO-BIPHEP: R � CH3O, X � Cl

P-Phos

SEGPHOS: X � H

Difluorphos: X � F

SYNPHOS

(BisbenzodioxanPhos)

CnTunaPhos

(n � 1–6)

Bitianp

X

X

Figure 1.2 (R)-BINAP and selected chiral biaryl diphosphines.

2 | 1 BINAP

CH001 18 January 2011; 14:52:17

(BisbenzodioxanPhos) [9], P-Phos [10], and Difluorphos [11], place the “equatorial”

phenyl groups in forward regions, providing highly contrasted chiral structures.

The chiral structures are varied by the size of the P1–M–P2 angle. CnTunaphos(n ¼ 1–6) can control the angle by changing the number of CH2 moieties [12].

H8-BINAP [13] and BIPHEMP [14], which are alkylated biphenyl diphosphines,

exhibit some unique stereoselective characters. Heteroaromatic biaryl ligands,

Bitianp [15] and P-Phos, as well as fluorinated diphosphine, Difluorphos, are

expected to add some electronic perturbation in the catalytic systems.

In this chapter we introduce typical, but not comprehensive, asymmetric reac-

tions catalyzed by the BINAP–metal complexes, achieving excellent enantios-

electivity. Mechanistic considerations for some reactions are commented on with

molecular models.

1.2

Hydrogenation of Olefins

In 1980, highly enantioselective hydrogenation of a-(acylamino)acrylic acids and

esters catalyzed by the cationic BINAP–Rh(I) complexes was reported [16–18].

For example, (Z)-a-(benzamido)cinnamic acid is hydrogenated with [Rhf(R)-binapg(CH3OH)2]ClO4 to afford (S)-N-benzoylphenylalanine in 100% enantio-

meric excess (ee) and 97% yield [substrate/catalyst molar ratio (S/C) ¼ 100, 4

atm H2, room temperature), 48 h, in C2H5OH] (Scheme 1.1). In terms of enan-

tioselectivity this hydrogenation appears to be excellent; however, very careful

choice of reaction parameters, such as low substrate concentration and low

hydrogen pressure, is required [19–22]. The scope of the olefinic substrates is

insufficiently wide.

BINAP–Ru(II) catalysis resolved the above problems. Methyl (Z)-a-(acetamido)

cinnamate is hydrogenated in the presence of Ru(OCOCH3)2[(R)-binap] (S/C ¼ 200)

in CH3OH (1 atm H2, 30 1C, 24 h) to give methyl (R)-a-(acetamido)cinnamate in

92% ee and 100% yield (Scheme 1.2) [17, 23, 24]. Various olefinic substrates,

Ph2

Ph2

Rh

P OMe

OMeP

NHCOC6H5

COOH (R)-BINAP–Rh

C2H5OH

H

H

ClO4�

NHCOC6H5

COOH

S, 100% ee97% yield

�

� H2

4 atm

[Rh{(R)-binap}(CH3OH)2]ClO4

Scheme 1.1 Hydrogenation of (Z)-a-(benzamido)cinnamic acid with a BINAP–Rh catalyst.

1.2 Hydrogenation of Olefins | 3

CH001 18 January 2011; 14:52:17

including enamides, a,b- and b,g-unsaturated carboxylic acids, and allylic and

homoallylic alcohols, are converted into the desired products in high ee [25]. About

300 tons per year of optically active citronellol is produced by this hydrogenation

[26]. The citronellol synthesis, by the use of a Ru(II) catalyst with a MeO-BIPHEP

derivative, is applied to the production of vitamin E [27]. The H8-BINAP–Ru

(II) catalyst reduces a,b-unsaturated carboxylic acids with even higher enantios-

electivity [28].

Figure 1.3 illustrates a mechanism for the hydrogenation of methyl (Z)-a-acetamidocinnamate catalyzed by the BINAP–Ru(II) complex [19, 20, 23]. Pre-

catalyst Ru(OCOCH3)2[(R)-binap] [(R)-1] was converted into the RuH(OCOCH3)

complex 2, which is an active species, under a H2 atmosphere with release of

CH3CO2H. The enamide substrate reversibly coordinates to the Ru center in

bidentate fashion, forming 3. Migratory insertion gives 4, followed by Ru–C

bond cleavage largely by H2, but also by CH3OH solvent to some extent, resulting

in the chiral product and regenerating the catalytic species 2. The stereochemistry

of the product is determined at the irreversible step (4-2). Because the

reactivities of the two diastereomers of 4 are similar, the enantioselectivity of

the product corresponds well to the relative stability (population) of the diaster-

eomeric enamide–RuH(OCOCH3) intermediates [not transition states (TSs)], Si-3and Re-3 (Figure 1.4). The Si-3 is more favored over the diastereomeric isomer

Re-3, because the latter suffers nonbonded repulsion between an equatorial phenyl

ring of the (R)-BINAP and the methoxycarbonyl group of substrate. Therefore,

the major (favored) intermediate Si-3 is converted into the (R) hydrogenation

product via 4.

CO2CH3

NHCOCH3

H2

CO2CH3

NHCOCH3

�

Ph2

Ph2

O

O

Ru

O

OP

P

NCHO

OCH3

OCH3

CH3O

CH3O

CH3OH

CO2H

CH3OOH

R, 92% ee

100% yield

R, �99.5% ee

with (R)-BINAP–Ru

S, 97% ee

with (S)-BINAP–Ru

R, 98% ee

with (S)-BINAP–Ru

(R)-BINAP–Ru

1 atm

Ru(OCOCH3)2[(R)-binap]

Scheme 1.2 Hydrogenation of functionalized olefins catalyzed by BINAP–Ru complexes.

4 | 1 BINAP

CH001 18 January 2011; 14:52:17

(P–P)(AcO)HRu

O

NH

Me

COOMe

(P–P)(AcO)Ru

O

NH

Me

COOMe

H

MeOOC NHCOMe

H

H(P–P)RuH(OAc)

R

(R)-2

(P–P)Ru(OAc)2

�H2

MeOOC NHCOMe

H2

�AcOH

P–P � (R)-BINAP

34

(R)-1

Figure 1.3 Catalytic cycle of BINAP–Ru catalyzed hydrogenation of methyl

(Z)-a-acetamidocinnamate. (For clarity the b-substituents in the substrates are omitted.)

X

H

X

RuO

ZH

H

Z

PhH

HN

CH3

O

Ph/Z

repulsion

X � OCOCH3, Z � CO2CH3

Ru PP

Si-3 (favored) Re-3 (unfavored)

H

N

CH3

Pheq eq

eqqeax ax

ax ax

(R)-BINAP

132

4

Figure 1.4 Molecular models of diastereomeric (R)-BINAP/enamide Ru complexes 3

(not transition state).

1.2 Hydrogenation of Olefins | 5

CH001 18 January 2011; 14:52:17

1.3

Hydrogenation of Ketones

1.3.1

Functionalized Ketones

Ru(OCOCH3)2(binap) is feebly active for the hydrogenation of ketones, although it

shows remarkable catalytic efficiency for the reaction of functionalized olefins.

This problem is resolved simply by replacing the carboxylate ligands with halides.

For instance, b-keto esters (R ¼ alkyl) are hydrogenated with RuCl2(binap)

(polymeric form; S/C ¼ 2000) in CH3OH (100 atm H2, 30 1C, 36 h) to give the b-hydroxy esters in W99% ee quantitatively (Scheme 1.3) [29, 30]. A turnover

number (TON) of 10 000 is achieved in the best cases. Several related complexes

exhibit comparable catalytic efficiency, including RuCl2(binap)(dmf)n (oligomeric

form) [31], [RuCl(binap)(arene)]Cl [6, 32], [NH2(C2H5)2][fRuCl(binap)g2(m-Cl)3][24, 33], and other in situ prepared halogen-containing BINAP–Ru complexes [34].

A range of a-, b-, and g-hetero substituted ketones as well as difunctionalized

ketones and diketones is converted into the chiral alcohols in high ee (Scheme 1.3)

[17, 35, 36]. Ruthenium(II) complexes with biaryldiphosphines that have smaller

dihedral angles (MeO-BIPHEP [37], P-Phos [10], SEGPHOS [8], and SYNPHOS

[9]) hydrogenate an aromatic b-keto ester (R ¼ C6H5) in high stereoselectivity [38].

For the reaction of an analogue with trifluoromethyl group (R ¼ CF3), the

Difluorphos–Ru(II) complex exhibits fine enantioselectivity [11]. The electronic

deficient character of this ligand is supposed to be important.

Ph2

Ph2

Ru

P S

SP

Cl

Cl

R OCH3

OO

H2

(R)-BINAP–Ru

CH3OH R OCH3

OOH

R, �99% ee

99% yield

�

R � alkyl, S � solvent or a weak ligand

N(CH3)2

OH

R, 99% ee

R, 99.5% ee

P(OC2H5)2

OH O

R, 99% ee

O

O

100 atm

OC2H5

OOH

Cl

S, 97% ee (100 °C)

OH OH

R,R, 100% ee

RuCl2[(R)-binap](S)n

Scheme 1.3 Hydrogenation of functionalized ketones catalyzed by BINAP–Ru complexes.

6 | 1 BINAP

CH001 18 January 2011; 14:52:17

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