Catalytic Asymmetric Conjugate Reactions E-Book

• Herausgeber: Wiley-VCH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 652

Veröffentlichungsjahr: 2010

Beschreibung

This unique and long-awaited handbook on this important topic in the hot field of stereoselective organic synthesis covers several types of nucleophiles. Top international authors deal with modern forms of achieving stereoselective conjugate additions based on the use of chiral auxiliaries or asymmetric catalysis, such as P-N ligands, organocatalysis, domino reactions, Lewis acid and base catalysis. There is also a discussion of the employment of enantioselective conjugate addition transformations in total synthesis of important molecules. With its reliable and previously unpublished experimental procedures, this is a true source of high quality information.

Leseprobe

Table of Contents

Related Titles

Title Page

Copyright

Preface

List of Contributors

1 Rhodium- and Palladium-Catalyzed Asymmetric Conjugate Additions

1.1 Introduction

1.2 Rh-Catalyzed ECA of Organoboron Reagents

1.3 Rh-Catalyzed ECA Organotitanium and Organozinc Reagents

1.4 Rh-Catalyzed ECA of Organosilicon Reagents

1.5 Rh-Catalyzed ECA with Other Organometallic Reagents

1.6 Rh-Catalyzed ECA of Alkynes

1.7 Rh-Catalyzed Tandem Processes

1.8 1,6-Conjugate Additions

1.9 Pd-Catalyzed ECA

1.10 Conclusions

2 Cu- and Ni-Catalyzed Conjugated Additions of Organozincs and Organoaluminums to α,β-Unsaturated Carbonyl Compounds

2.1 Introduction

2.2 General Aspects

2.3 Conjugated Additions

2.4 Ligands for Cu-Catalyzed Enantioselective Conjugated Additions

2.5 Ligands for Ni-Catalyzed Enantioselective Conjugated Additions

2.6 Application of Conjugated Additions in the Synthesis of Natural Compounds

2.7 Conclusions

3 ECAs of Organolithium Reagents, Grignard Reagents, and Examples of Cu-Catalyzed ECAs

3.1 Introduction

3.2 Enantioselective Conjugate Addition of Lithium Reagents

3.3 Catalytic Enantioselective Conjugate Addition of Grignard Reagents

3.4 Cu-Complexes as Catalysts for Enantioselective Conjugate Additions

3.5 Conclusions

4 Asymmetric Bifunctional Catalysis Using Heterobimetallic and Multimetallic Systems in Enantioselective Conjugate Additions

4.1 Introduction

4.2 Dinuclear Zn-Complexes in Catalytic ECAs

4.3 Heterobimetallic Rare-Earth–Alkali Metal-Binol Complexes in ECAs

4.4 Heterobimetallic Rare-earth–Alkali Metal-Binol Complexes in ECAs of Heteroatom Nucleophiles

4.5 Miscellaneous

4.6 Conclusion

5 Enamines in Catalytic Enantioselective Conjugate Additions

5.1 Introduction and Background

5.2 Mechanistic Considerations

5.3 Ketone Conjugate Additions

5.4 Aldehyde Conjugate Additions

5.5 Tandem or Cascade Reactions

5.6 Conclusions

5.7 Experimental

6 Iminium Activation in Catalytic Enantioselective Conjugate Additions

6.1 Introduction

6.2 Mechanistic Aspects of the Iminium Activation Concept, and Factors Influencing Stereocontrol in Michael Additions

6.3 Michael Reactions

6.4 Conjugate Friedel-Crafts Alkylations

6.5 Conjugate Hydrogen-Transfer Reactions

6.6 Conjugate Additions of Heteronucleophiles

6.7 Cascade Reactions

6.8 Concluding Remarks and Outlook

7 Organocatalytic Enantioselective Conjugate Additions of Heteroatoms to α,β-Unsaturated Carbonyl Compounds

7.1 Introduction

7.2 “N” as Nucleophiles

7.3 “O” as Nucleophiles

7.4 “S” as Nucleophiles

7.5 “P” as Nucleophiles

7.6 Concluding Remarks

8 Domino Reactions Involving Catalytic Enantioselective Conjugate Additions

8.1 Introduction

8.2 Metal-Mediated Domino Michael/Aldol Reactions

8.3 Metal-Mediated Domino Michael Reaction/Electrophile Trapping with Noncarbonyl Compounds

8.4 Organocatalytic Domino Michael Reactions/Electrophilic Trapping

8.5 1,4-Conjugate Additions Followed by a Cycloaddition, Hydrogenation, Rearrangement, or Other Reactions

8.6 Conclusion

9 Asymmetric Epoxidations of α, β-Unsaturated Carbonyl Compounds

9.1 Introduction

9.2 Metal-Catalyzed Epoxidations

9.3 Organocatalyzed Epoxidations

9.4 Conclusions

9.5 Experimental

10 Catalytic Asymmetric Baylis–Hillman Reactions and Surroundings

10.1 Introduction

10.2 The Reaction Mechanism

10.3 Asymmetric Intermolecular Baylis–Hillman Reaction

10.4 Asymmetric Intramolecular Morita–Baylis–Hillman Reaction

10.5 Conclusions

Index

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The Editor

Prof. Armando Córdova

Department of Organic Chemistry Stockholm University Arrhenius Laboratory 106 91 Stockholm Schweden

Cover

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.

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A catalogue record for this book is available from the British Library.

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The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <http://dnb.d-nb.de>.

© 2010 WILEY-VCH Verlag GmbH & 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, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.

ISBN: 978-3-527-32411-8

Preface

The stereoselective conjugate reaction is one of the most important transformations in organic synthesis to achieve asymmetric carbon–carbon and heteroatom-carbon bond-forming reactions. There is today no such book that is focused on this topic. In particular, there is need for a book that covers catalytic asymmetric methods. The last book on the general topic of conjugate reactions in organic synthesis was published in 1992 and the discussion of stereoselective reactions is a small part. This book covers catalytic asymmetric methods based on conjugate additions, which are catalyzed by organometallic complexes or small organic molecules. Significant efforts have been made in asymmetric catalysis during this decade and pioneers of this field were awarded the Nobel prize in 2001. Thus, a book that focuses on modern methods on catalytic stereoselective conjugate addition reactions is highly desirable for the chemistry community.

I would like to thank all the distinguished scientists and their coauthors for their rewarding and timely contributions. I gratefully acknowledge the Wiley-VCH editorial staff, in particular to Dr. Elke Maase for proposing to me this excellent topic and to Dr. Waltraud Wuest who was of precious help for the development of this project.

Armando Córdova

Stockholm, April 2010

List of Contributors

Dolores Badía

University of the Basque Country

Faculty of Science and Technology

Department of Organic Chemistry II

P.O. Box 644, 48080 Bilbao

Spain

Guillaume Berthon

Syngenta Crop Protection Münchwilen AG

Schaffhauserstrasse

Postfach 4332, Stein

Switzerland

Robert Betík

Department of Organic and Nuclear Chemistry

Faculty of Science

Charles University in Prague

Hlavova 8, 128 43 Praha 2

Czech Republic

Luisa Carrillo

University of the Basque Country

Faculty of Science and Technology

Department of Organic Chemistry II

P.O. Box 644, 48080 Bilbao

Spain

Armando Córdova

Stockholm University

Department of Organic Chemistry

Arrhenius Laboratory

Svante Arrhenius väg 16 C

plan 6, 10691 Stockholm

Sweden

Alexander Düfert

Universität Göttingen

Institut für Organische und Biomolekulare Chemie

Tammannstr. 2

37077 Göttingen

Germany

Tamio Hayashi

Kyoto University

Graduate School of Science

Department of Chemistry

Rigakubu-ichi-goukan

Kyoto 606-8502

Japan

Martin Kotora

Department of Organic and Nuclear Chemistry

Faculty of Science

Charles University in Prague

Hlavova 8, 128 43 Praha 2

Czech Republic

and

Institute of Organic Chemistry and Biochemistry

Academy of Sciences of the Czech Republic

Flemingovo n. 2, 166 10 Praha 6

Czech Republic

Alessandra Lattanzi

Universitá di Salerno

Dipartimento di Chimica

Via Ponte don Melillo

84084 Fisciano

Italy

Albert Moyano

University of Barcelona

Department of Organic Chemistry

Martí i Franquès, 1-11

08028 Barcelona

Spain

Efraim Reyes

University of the Basque Country

Faculty of Science and Technology

Department of Organic Chemistry II

P.O. Box 644, 48080 Bilbao

Spain

Ramon Rios

University of Barcelona

Department of Organic Chemistry

Martí i Franquès, 1-11

08028 Barcelona

Spain

Lutz F. Tietze

Universität Göttingen

Institut für Organische und Biomolekulare Chemie

Tammannstr. 2, 37077 Göttingen

Germany

Jose L. Vicario

University of the Basque Country

Faculty of Science and Technology

Department of Organic Chemistry II

P.O. Box 644, 48080 Bilbao

Spain

Wei Wang

University of New Mexico

Department of Chemistry and Chemical Biology

Clark Hall B-56

Albuquerque, NM 87131-0001

USA

Shilei Zhang

University of New Mexico

Department of Chemistry and Chemical Biology

Clark Hall B-56

Albuquerque, NM 87131-0001

USA

Gui-Ling Zhao

Stockholm University

Department of Organic Chemistry

Arrhenius Laboratory

Svante Arrhenius väg 16 C

plan 6, 10691 Stockholm

Sweden

1

Rhodium- and Palladium-Catalyzed Asymmetric Conjugate Additions

Guillaume Berthon

Tamio Hayashi

1.1 Introduction

Since the seminal report by Uemura (1) in 1995 for palladium, and by Miyaura in 1997 for rhodium (2), the late transition metal-catalyzed conjugate addition of organoboron reagents to activated alkenes has emerged as one of the most functional group-tolerant and reliable carbon–carbon bond-forming processes. The maturity of this methodology is such that it has become an ideal testing ground for new ligand concepts and design, as will be illustrated throughout this chapter. A true statement to the robustness of this process is the application of Rh-catalyzed enantioselective conjugate addition (ECA) on a kilogram-scale for the manufacture of advanced pharmaceutical ingredients, and its use as a key step in the synthesis of complex natural products (3, 4, 5).

In this chapter, an overview will be provided – spanning from 2003 to mid-2009 – of the developments in the field of rhodium- and palladium-catalyzed ECA of organometallic reagents (B, Si, Zn, and Ti) to activated alkenes. The chapter is not intended to be comprehensive, and will include only selected examples of this powerful methodology. For more in-depth and comprehensive accounts, the reader should consult a number of excellent reviews that are available on this subject (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16).

1.2 Rh-Catalyzed ECA of Organoboron Reagents

This section will include details of the state of the art for the rhodium-catalyzed ECA of organoboron reagents to activated olefins. Special emphasis will be placed on α, β-unsaturated ketones, as this substrate class has attracted the most attention and undergone thorough investigation with a plethora of different ligand systems. Many of the findings described for α, β-unsaturated ketones are also applicable to other olefin classes and other nucleophilic organometallic reagents, unless otherwise specified.

1.2.1 α, β-Unsaturated Ketones

1.2.1.1 A Short History

The first example of conjugate addition of an arylboronic acid to an enone catalyzed by transition metal complexes can be traced back to a report from 1995 by Uemura and coworkers (1). This reaction was carried out ligand-less and with a high catalyst loading (10 mol%). The interest in this reaction remained limited until 1997, when Miyaura reported that the [Rh(acac)(CO)2]/dppb (acac = acetylacetonato; dppb = 1,4-bis(diphenylphosphino)butane) system would efficiently catalyze the conjugate addition of a wide range of aryl- and alkenylboronic acids to methyl vinyl ketone (MVK) in high yields, and also to β-substituted enones including 2-cyclohexenone, albeit in lower yields (Scheme 1.1) (2).

Scheme 1.1 Seminal report of Rh-catalyzed conjugate addition of organoboronic acids.

The hallmarks of this reaction are: (i) no competitive uncatalyzed reaction of the organoboronic acids onto the enone; (ii) no 1,2-addition of the organoboron reagent; and (iii) a large functional group tolerance which is in contrast to organolithium and Grignard reagents.

A real breakthrough in this methodology came in 1998, when Hayashi and Miyaura described the first example of a rhodium-catalyzed ECA (17). For the first time, a wide range of aryl and alkenyl fragments could be added in high yields and with exquisite enantioselectivity to an α, β-unsaturated ketone using (S)-binap ((S)-L1) as the chiral diphosphine ligand (Scheme 1.2) (17). Since this initial report, great progress has also been made in the copper-catalyzed ECA using Grignard and organozinc reagents (this subject is treated in detail in Chapter 3) (18, 19, 20, 21). In order to achieve such high enantioselectivities in the Rh-catalyzed ECA, several factors had to be modified from the original conditions: namely, the rhodium precursor was changed from [Rh(acac)(CO)2] to [Rh(acac)(C2 H4)2]; the solvent system was changed to 1,4-dioxane/H2O (10 : 1); the temperature was increased to 100 °C; and the reaction time was shortened to 5 h. The scope of the reaction was very broad, and a wide range of arylboronic acids (2) substituted with electron-donating or -withdrawing groups could be added to 2-cyclohexenone (1a) with high enantioselectivities (Scheme 1.2, entries 2–5). The ECA of alkenylboronic acids 4m and 4n to 2-cyclohexenone and 2-cyclopentenone was also very selective (Scheme 1.2, entries 11 and 12). Linear enones having a trans geometry also gave high enantioselectivities (Scheme 1.2, entries 8 and 9).

Scheme 1.2 ECA of organoboronic acids to α, β-unsaturated ketones catalyzed by [Rh(acac)(C2H4)]/(S)-binap.

These key seminal findings set the stage for an intense research activity in the area of rhodium-catalyzed ECAs, and related processes, which goes unabated in 2009. In the following sections, the mechanism will be discuss and a working model postulated for the observed enantioselectivity. Using the insights brought by the mechanistic studies, the importance of the Rh precatalyst, as well of the organoboron derivatives that can be used, will also be discussed. An overview will then be presented, by ligand class, of all ligands systems reported until mid-2009, after which the different substrate classes and other competent organometallic reagents in Rh-catalyzed ECA will be reviewed. Following a section devoted to tandem processes involving a conjugate addition step, the chapter will conclude with details of the palladium catalysts for ECAs.

1.2.1.2 Catalytic Cycle

In 2002, Hayashi and coworkers established the detailed mechanistic cycle for the rhodium-catalyzed ECA. An example of this catalytic cycle for the ECA of phenylboronic acid onto 2-cyclohexenone (1a) is given in Scheme 1.3 (22). The cycle goes through three identifiable intermediates: the hydroxyrhodium A; the phenylrhodium B; and the oxa-π-allylrhodium (rhodium-enolate) C complexes. These intermediates are related to the cycle as follows. The reaction is initiated through the transmetallation of a phenyl group from boron to hydroxyrhodium to generate the phenylrhodium . The 2-cyclohexenone will subsequently insert into Rh–Ph bond of to form the oxa-π-allylrhodium . The rhodium enolate is unstable under protic condition, and will be readily hydrolyzed to regenerate and liberate the ECA product. It is important to note that, throughout the catalytic cycle, rhodium remains at a constant oxidation state of +I.