Literature ReportLiterature ReportBy Liu, YuanyuanBy Liu, Yuanyuan

2011.04.092011.04.09

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Intramolecular aminopalladation of Intramolecular aminopalladation of alkenes alkenes as a key step to pyrrolidinesas a key step to pyrrolidines

and related heterocyclesand related heterocycles

Ref:Ref:

K.K. Muniz, A. Minatti Muniz, A. Minatti Chem. Soc. RevChem. Soc. Rev., ., 20072007, , 3636, 1142., 1142.

By Ana Minatti and Kilian MunizBy Ana Minatti and Kilian Muniz

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Table of ContentsTable of Contents

1. Introduction1. Introduction

2. 2. AminopalladationAminopalladation

3. 3. Several related reactionsSeveral related reactions

55. . Summary and outlookSummary and outlook

4. 4. Enantioselective aminopalladationEnantioselective aminopalladation

4

Ana MinattiAna MinattiAna Minatti was born in Bonn, Germany in 1977. She studied chemistry at the University of Bonn and graduated in 2001 with highest honours. That year she commenced her PhD studies in the research group of Karl-Heinz Dotz

and worked on Fischer-carbene-complexes as a tool for ligand and natural product synthesis. She obtained her PhD in Organic and Organometallic Chemistry in 2006.

She further worked for three months on iodoniuminduced cyclization reactions in the research group of Jose Barluenga

at the

University of Oviedo, Spain. In 2006, she joined the research group of Stephen L. Buchwald

at the Massachusetts Institute of Technology. She

received a Theodor-Laymann-fellowship

from the University of Bonn, a PhD fellowship

from the Fonds der Chemischen Industrie, a

DAAD exchange fellowship

and a postdoctoral fellowship

from the Alexander-von-Humboldt foundation. In 2006, she was awarded the Edmund-ter-Meer-prize

from the University of Bonn.

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Kilian MunizKilian MunizKilian Muniz was born in 1970. From 1990 to 1996 he studied Chemistry at Hannover University, Germany, at the Imperial College London, UK and at University of Oviedo, Spain. In 1996 he joined the group of Carsten Bolm

at the

RWTH Aachen, Germany to obtain his doctorate in 1998. In 1999/2000 he worked as a postdoctoral associate

with Ryoji

Noyori

at Nagoya

University, Japan.

He began his independent research in December 2000 at the Kekule-Department in Bonn, Germany to finish his Habilitation in 2005. In the autumn of 2005 he joined the Institut de Chimie at ULP Strasbourg as an Associate Professor

and was promoted to

Full Professor

in 2006. His research has been recognised by several awards and honours, among them the German–Israeli Young Investor Award

and the German ADUC Prize for Habilitands. In

2006 he was awarded a Chaire d’Excellence

from the French National Research Agency.

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IntroductionIntroductionIntroduction

Synthesis of nitrogen heterocycles

through C–N bond formation

represents a useful

and widely applied synthetic tool. The application of transition metal complexes as catalysts for this process has been considered an attractive approach, and palladium salts

have emerged as

particularly exciting catalysts over the course of the past two decades.

Ref:

J. Tsuji, Palladium Reagents and Catalysts, Wiley, New York, 2004.

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IntroductionIntroductionIntroduction

electron rich functional character

Their direct reaction is characterised by a high activation energy and is usually not straightforward.

However, coordination to a transition metal centre such as palladium(II) induces an umpolung of the original alkene reactivity and renders the alkene susceptible to nucleophilic attack.

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Table of ContentsTable of Contents

1. Introduction1. Introduction

2. 2. AminopalladationAminopalladation

3. 3. Several related reactionsSeveral related reactions

55. . Summary and outlookSummary and outlook

4. 4. Enantioselective aminopalladationEnantioselective aminopalladation

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AminopalladationAminopalladationAminopalladation

Mechanistic background of aminopalladation for heterocycle synthesis

The exact pathways remain unknown, but in principle:

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In the following, we will discuss the reaction conditions for intramolecular aminopalladation and subsequent

selective transformations of the resulting alkyl– palladium bond

in order to generate functionalised

nitrogen heterocycles. These reactions will be presented in a subjective order where it is intended to show structural similarities arising from different reaction conditions. These may involve catalysts with differentiating metal oxidation states,

namely, reactions without Pd(II)

oxidation state change, those by classical Pd(0)/Pd(II) catalysis

and those which presumably follow a

Pd(II)/Pd(IV) oxidation state cycle.

AminopalladationAminopalladationAminopalladation

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Table of ContentsTable of Contents

1. Introduction1. Introduction

2. 2. AminopalladationAminopalladation

3. 3. Several related reactionsSeveral related reactions

55. . Summary and outlookSummary and outlook

4. 4. Enantioselective aminopalladationEnantioselective aminopalladation

12

Enantioselective aminopalladationEnantioselective aminopalladationEnantioselective aminopalladation

Ref: L. E. Overman and T. P. Remarchuk, J. Am. Chem. Soc., 2002, 124, 12;For the achiral variant: A. Lei, G. Liu and X. Lu, J. Org. Chem., 2002, 67, 974;S. F. Kirsch and L. E. Overman, J. Org. Chem., 2005, 70, 2859.

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Table of ContentsTable of Contents

1. Introduction1. Introduction

2. 2. AminopalladationAminopalladation

3. 3. Several related reactionsSeveral related reactions

55. . Summary and outlookSummary and outlook

4. 4. Enantioselective aminopalladationEnantioselective aminopalladation

15

Hydroamination reactionHydroamination reaction

In principle, 2-aminoalkyl palladium compounds should serve as suitable intermediates

for

hydroamination processes of unactivated alkenes. By this, simple

pyrrolidines, piperidines

and related

heterocyclic cores

should be accessible from protonolysis of the carbon-palladium bond. Such a process had posed a significant long-term problem

since organometallic

palladium intermediates usually undergo -hydride elimination (vide infra) at a higher rate.

16

Ref: F. E. Michael and B. M. Cochran, J. Am. Chem. Soc., 2006, 128, 4246;C. Hahn, A. Vitagliano, F. Giordano and R. Taube, Organometallics, 1998, 17, 2060.

The pincer ligand is believed to prevent formation of any open coordination sides at palladium, thereby suppressing undesired reactions such as -hydride elimination

to take place.

17

Aza-Wacker reactionsAza-Wacker reactions

For the elaboration of more diversified structures, simple hydroamination

represents a less desirable

process. --Hydride elimination processesHydride elimination processes

represent represent standard demetallation reactions in organometallic standard demetallation reactions in organometallic chemistrychemistry..

As such, it has also found wide application

in palladium-catalysed intramolecular amination reactions and, in principle, constitutes the most productive pathway

once the initial aminopalladation

has taken place. Depending on the substitution pattern, -hydride elimination of 2-aminoalkyl palladium can furnish enamides or allylic amides, respectively, the latter representing the more common product.

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Ref: R. C. Larock, T. R. Hightower, L. A. Hasvold and K. P. Peterson, J. Org. Chem., 1996, 61, 3584;

M. M. Rogers, J. E. Wendlandt, I. A. Guzei and S. S. Stahl, Org. Lett., 2006, 8, 2257.

19

Ref:

R. C. Larock, T. R. Hightower, L. A. Hasvold and K. P. Peterson, J. Org. Chem., 1996, 61, 3584; S. R. Fix, J. L. Brice and S. S. Stahl, Angew. Chem., Int. Ed., 2002, 41, 164; R. M. Trend, Y. K. Ramtohul, E. M. Ferreira and B. M. Stoltz, Angew. Chem., Int. Ed., 2003, 42, 2892; M. M. Rogers, J. E. Wendlandt, I. A. Guzei and S. S. Stahl, Org. Lett., 2006, 8, 2257.

20Ref: X. Ye, G. Liu, B. V. Popp, and S. S. Stahl, J. Org. Chem. 2011, 76, 1031.

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Amino-Heck-type reactionsAmino-Heck-type reactions

Ref: J. E. Ney and J. P. Wolfe, Angew. Chem., Int. Ed., 2004, 43, 3605;J. E. Ney, M. B. Hay, Q. Yang and J. P. Wolfe, Adv. Synth. Catal.,2005, 347, 1614.

22Ref: J. E. Ney and J. P. Wolfe, J. Am. Chem. Soc., 2005, 127, 8644.

23

Ref: J. E. Ney, M. B. Hay, Q. Yang and J. P. Wolfe, Adv. Synth. Catal.,2005, 347, 1614;R. Lira and J. P. Wolfe, J. Am. Chem. Soc., 2004, 126, 13906; Q. Yang, J. E. Ney and J. P. Wolfe, Org. Lett., 2005, 7, 2575; M. B. Bertrand and J. P. Wolfe, Org. Lett., 2006, 8, 2353.

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Ref: J. E. Ney, M. B. Hay, Q. Yang and J. P. Wolfe, Adv. Synth. Catal.,2005, 347, 1614;J. S. Nakhla, J. W. Kampf and J. P. Wolfe, J. Am. Chem. Soc., 2006, 128, 2893.

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Aza-Heck-type reactionsAza-Heck-type reactions

Ref: M. Kitamura and K. Narasaka, Chem. Rec., 2002, 2, 268;K. Narasaka and M. Kitamura, Eur. J. Org. Chem., 2005, 4505;S. Zaman, M. Kitamura and K. Narasaka, Bull. Chem. Soc. Jpn., 2003, 76, 1055.

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Ref: S. Chiba, M. Kitamura, O. Saku and K. Narasaka, Bull. Chem. Soc. Jpn., 2004, 77, 785;J. Helaja and R. Gottlich, Chem. Commun., 2002, 720.

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Aminocarbonylation reactionsAminocarbonylation reactions

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Ref: Y. Tamaru, H. Tanigawa, S. Itoh, M. Kimura, S. Tanaka, K. Fugami, T. Sekiyama and Z.-i. Yoshida, Tetrahedron Lett., 1992, 33, 631; Y. Tamaru, M. Hojo and Z.-i. Yoshida, J. Org. Chem., 1988, 53, 5731; Y. Tamaru, M. Hojo, H. Higashimura and Z.-i. Yoshida, J. Am. Chem. Soc., 1988, 110, 3994.

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Ref: T. Tsujihara, T. Shinohara, K. Takenaka, S. Takizawa, K. Onitsuka, M. Hatanaka, and H. Sasai, J. Org. Chem. 2009, 74, 9274.

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Aminocarbonation reactionsAminocarbonation reactions

Ref: K.-T. Yip, M. Yang, K.-L. Law, N.-Y. Zhu and D. Yang, J. Am. Chem. Soc., 2006, 128, 3130; R. M. Trend, Y. K. Ramtohul and B. M. Stoltz, J. Am. Chem. Soc., 2005, 127, 17778.

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Aminohalogenation reactionsAminohalogenation reactions

Ref: Y. Tamaru, M. Hojo, H. Higashimura and Z.-i. Yoshida, J. Am. Chem. Soc., 1988, 110, 3994; M. R. Manzoni, T. P. Zabawa, D. Kasi and S. R. Chemler, Organometallics, 2004, 23, 5618.

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Ref: A. Lei, X. Lu and G. Liu, Tetrahedron Lett., 2004, 45, 1785;P. Szolcsanyi and T. Gracza, Tetrahedron, 2006, 62, 8498.

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R1 R2

NHTs3

Pd(OAc)2(10 mol %)

PhI(OCOtBu)2(2 equiv)

AgF (5 equiv)MgSO4 (100 mg)

CH3CNr.t.

N

R1

R2 F

4Ts

Ref: T. Wu, G. Yin, and G. Liu, J. Am. Chem. Soc. 2009, 131, 16354.

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Aminoacetoxylation reactionsAminoacetoxylation reactions

Ref: E. J. Alexanian, C. Lee and E. J. Sorensen, J. Am. Chem. Soc., 2005, 127, 7690.

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Diamination reactionsDiamination reactions

Ref: J. Streuff, C. H. Hovelmann, M. Nieger and K. Muniz, J. Am. Chem. Soc., 2005, 127, 14587.

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Table of ContentsTable of Contents

1. Introduction1. Introduction

2. 2. AminopalladationAminopalladation

3. 3. Several related reactionsSeveral related reactions

55. . Summary and outlookSummary and outlook

4. 4. Enantioselective aminopalladationEnantioselective aminopalladation

39

Summary and outlookSummary and outlookSummary and outlook

While the initial aminopalladation

necessarily requires palladium(II) as the catalyst oxidation

state, the exact course

of the subsequent catalysissteps to a large extent depend on the chosen reaction conditions, among which the electronic situation at the palladium centre is a key issue.

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At present, several open issues remain to be solved:

1.

A broader scope regarding internal alkenes. 2.

The development of efficient ligands

for palladium.

(hydroamination) 3.

The development of suitable chiral

ligands

for

asymmetric protocols is obviously a necessary task to ensure access to enantiomerically

enriched

heterocycles. (biomolecules)4.

Especially desirable for the oxidative processes

of

aminohalogenation, aminoacetoxylation

and diamination.

Thank you!Thank you!By Liu, YuanyuanBy Liu, Yuanyuan

2011.04.092011.04.09