Comprehensive Enantioselective Organocatalysis E-Book
502,99 €
Mehr erfahren.
- Herausgeber: Wiley-VCH
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Structured in three parts this manual recollects efficient organocatalytic transformations around clear principles that meet actual standard in asymmetric synthesis. Chapters were written by acknowledged leaders of the organocatalysis field, and are presented in a concise way. Volume 1: Privileged Catalysts gives insight to readers to the continuously increasing variety of catalysts, and the relatively complex interactions that make organocatalytic reactions selective. An appendix recollects catalyst structures with the adequate cross-references. Volume 2: Activations covers the fundamental activation types (non-covalent and covalent activations) and helps understanding the importance of physical parameters, and in particular, the role of water, that influences reactivity and selectivity. Volume 3: Reactions and Applications highlights transformations by reaction types. The final part of this volume is dedicated to application in multistep synthesis and industrial applications.
Considering the ever increasing interest in the organocatalysis field, the book aims addressing to a large audience: to academic, and, industrial researchers, students and teachers who are interested in synthetic organic chemistry at advanced level. This book provides non-specialists with an introduction to the topic as well as serving as a valuable source for newcomers and researchers searching for an up-to-date and comprehensive overview of this promising area of synthetic organic chemistry.
Sie lesen das E-Book in den Legimi-Apps auf:
Seitenzahl: 2036
Veröffentlichungsjahr: 2013
Ähnliche
Table of Contents
Related Titles
Title page
Copyright page
Foreword
Preface
List of Contributors
Abbreviations
Volume 1: Privileged Catalysts
Part I: Amino Acid-Derived Catalysts
1: Proline-Related Secondary Amine Catalysts and Applications
1.1 Introduction
1.2 Prolinamide and Related Catalysts
1.3 Prolinamine and Related Catalysts
1.4 Proline Tetrazole and Related Catalysts
1.5 Prolinamine Sulfonamide and Related Catalysts
1.6 Prolinamine Thiourea and Related Catalysts
1.7 Miscellaneous
1.8 Conclusions
Acknowledgments
2: TMS-Prolinol Catalyst in Organocatalysis
2.1 Introduction
2.2 Enamine Activation
2.3 Iminium-Ion Activation
2.4 Cascade Reactions
2.5 Dienamine Activation
2.6 Trienamine Activation
2.7 Summary and Conclusions
3: Non-Proline Amino Acid Catalysts
3.1 Introduction
3.2 Primary Amino Acids in Amino Catalysis
3.3 Primary Amino Acid-Derived Organic Catalysts
3.4 Applications of Non-Proline Primary Amino Acid Catalysts
3.5 Conclusions
Acknowledgments
4: Chiral Imidazolidinone (MacMillan's) Catalyst
4.1 Introduction
4.2 Enamine Catalysis
4.3 Iminium Catalysis
4.4 Cascade Reaction–Merging Iminium and Enamine Catalysis
5: Oligopeptides as Modular Organocatalytic Scaffolds
5.1 Introduction
5.2 C–C Bond Forming Reactions
5.3 Asymmetric Acylations
5.4 Asymmetric Phosphorylations
5.5 Enantioselective Oxidations
5.6 Hydrolytic Reactions
5.7 Summary and Conclusions
Part II: Non-Amino Acid-Derived Catalysts
6: Cinchonas and Cupreidines
6.1 Introduction
6.2 Cinchona Alkaloid Derivatives
6.3 Natural Cinchona Alkaloids, Cupreine, and Cupreidine
6.4 Cinchona Alkaloids with an Ether or Ester Group at C9
6.5 Cinchona Alkaloid Derivatives with a Sulfonamide, Urea, Thiourea, Squaramide, or Guanidine Function
6.6 Cinchona Alkaloids with a Primary Amine Group at C9
6.7 Cinchona Alkaloids in Phase-Transfer Catalysis
6.8 Ether Bridged Dimers
6.9 Some Novel Cinchona Alkaloid Derivatives
6.10 Prospects
7: Chiral C2 Catalysts
7.1 Introduction
7.2 Chiral Lewis Base Catalysts
7.3 Phosphines
7.4 Chiral C2-Symmetric Secondary and Primary Amines
7.5 Chiral C2-Symmetric Brønsted Bases: Guanidines
7.6 Chiral C2-Symmetric Brønsted Acids
7.7 Chiral C2-Symmetric Bis-Thioureas
7.8 Chiral C2-Symmetric Aminophosphonium Ions
7.9 Summary and Conclusions
8: Planar Chiral Catalysts
8.1 Introduction
8.2 Lewis/Brønsted Bases
8.3 Lewis/Brønsted Acids
8.4 Redox Reactions
8.5 Summary and Conclusions
9: Dynamic Approaches towards Catalyst Discovery
9.1 Introduction
9.2 Self-Assembly
9.3 Self-Selected Catalysts
9.4 Conclusions
Acknowledgments
Appendix
Proline Derivatives and Proline Analogs
Non-Proline Amino Acids
Chiral Imidazolidinones (MacMillan's Catalysts and Analogs)
Di- and Oligopeptide Catalysts
Cinchonas
Planar Chiral Catalysts
Biaryl Catalysts
1,2-Diamines
1,2-Aminoalcohols
1,2-Aminophosphines
TADDOL-Derived Catalysts
Carbohydrate-Derived Catalysts
Terpene-Derived Catalysts
Chiral Sulfoxides
Miscellaneous
Volume 2: Activations
Part I: Asymmetric Catalysis with Non-Covalent Interactions
10: Brønsted Acids
10.1 Introduction
10.2 Chiral Alcohol Catalysts
10.3 Chiral Squaramides as Hydrogen-Bond Donor Catalysts
10.4 Guanidines/Guanidiniums
10.5 Miscellaneous Brønsted Acids
10.6 Addendum
11: Brønsted Acids: Chiral Phosphoric Acid Catalysts in Asymmetric Synthesis
11.1 Introduction
11.2 Reaction with Imines
11.3 Friedel–Crafts Reaction
11.4 Intramolecular Aldol Reaction
11.5 Ring Opening of meso-Aziridines
11.6 Future Prospects
12: Brønsted Acids: Chiral (Thio)urea Derivatives
12.1 Introduction
12.2 Important Chiral (Thio)urea Organocatalysts
12.3 Summary
13: Brønsted Bases
13.1 Introduction
13.2 Cinchona Alkaloids
13.3 Brønsted Base-Derived Thiourea Catalysts
13.4 Chiral Guanidine Catalysts
13.5 Conclusion
14: Chiral Onium Salts (Phase-Transfer Reactions)
14.1 Introduction
14.2 Phase-Transfer Catalysis
14.3 Onium Fluorides
14.4 Onium Phenoxides and Related Compounds
14.5 Conclusions
15: Lewis Bases
15.1 Introduction
15.2 Allylation Reactions
15.3 Propargylation, Allenylation, and Addition of Acetylenes
15.4 Aldol-Type Reactions
15.5 Cyanation and Isonitrile Addition
15.6 Reduction Reactions
15.7 Epoxide Opening
15.8 Conclusion and Outlook
16: Lewis Acids
16.1 Introduction
16.2 Silyl Cation Based Catalysts
16.3 Hypervalent Silicon Based Catalysts
16.4 Phosphonium Cation Based Catalysts
16.5 Carbocation Based Catalysts
16.6 Ionic Liquids
16.7 Miscellaneous Catalysts
16.8 Conclusion
Part II: Asymmetric Catalysis with Covalent Interactions
17: Rationalizing Reactivity and Selectivity in Aminocatalytic Reactions
17.1 Introduction
17.2 Secondary Amine Catalysis
17.3 Stereoselectivity in Proline-Catalyzed Reactions
17.4 Mechanism and Stereoselectivity in Organocatalytic Cascade Reactions
17.5 Rational Design of Catalysts
17.6 Summary and Conclusions
Acknowledgments
18: Carbene Catalysts
18.1 Introduction
18.2 Reactions of Acyl Anion Equivalents
18.3 Extended Umpolung
18.4 Umpolung of Activated Olefins
18.5 Nucleophilic Catalysis
18.6 Conclusion
19: Oxides and Epoxides
19.1 Alkene Epoxidation
19.2 Hypervalent Iodine-Catalyzed Oxidations
19.3 Oxidation of Thioethers and Disulfides
19.4 Resolution of Alcohols by Oxidation
20: Ylides
20.1 Introduction
20.2 Enantioselective Sulfur Ylide Catalysis
20.3 Enantioselective Phosphorus and Arsenic Ylide Catalysis
20.4 Enantioselective Nitrogen Ylide Catalysis
20.5 Enantioselective Selenium and Tellurium Ylide Catalysis
20.6 Summary and Conclusions
Part III: Tuning Catalyst Activity and Selectivity by the Reaction Medium and Conditions
21: “Non-Classical” Activation of Organocatalytic Reactions (Pressure, Microwave Irradiation.)
21.1 Introduction
21.2 Asymmetric Organocatalysis under High-Pressure Conditions
21.3 Asymmetric Organocatalysis under Microwave Irradiation–Thermal Effect
21.4 Asymmetric Organocatalysis under Ultrasound Irradiation
21.5 Asymmetric Organocatalysis under Ball Milling Conditions
21.6 Summary and Conclusions
22: Ionic Liquid Organocatalysts
22.1 Introduction
22.2 Ionic Liquids as Recyclable Solvents for Asymmetric Organocatalytic Reactions
22.3 “Non-Solvent” Applications of Ionic Liquids and Their Congeners in Asymmetric Organocatalysis
22.4 Conclusion
23: Polymer and Mesoporous Material Supported Organocatalysts
23.1 Introduction
23.2 Polymer-Supported Organocatalysts
23.3 Mesoporous-Supported Organocatalysts
23.4 Conclusions and Outlook
24: Water in Organocatalytic Reactions
24.1 Introduction
24.2 Aldol Reactions
24.3 Michael Reactions
24.4 Mannich Reaction
24.5 Diels–Alder Reaction
24.6 Miscellaneous Examples
Volume 3: Reactions and Applications
Part I: Alpha-Alkylation and Heteroatom Functionalization
25: SN2-Type Alpha-Alkylation and Allylation Reactions
25.1 SN2-Type Alkylation under Homogenous Conditions
25.2 Domino Reactions Including SN2-Type Alkylations
25.3 Intermolecular SN2′ Alkylations under Homogenous Conditions
25.4 Summary
26: Alpha-Alkylation by SN1-Type Reactions
26.1 Introduction
26.2 SN1-Type Nucleophilic Reaction by Generation of Carbocations
26.3 Organocatalytic Stereoselective SN1-Type Reactions with Enamine Catalysis
26.4 Asymmetric SN1-Type α-Alkylation of Ketones
26.5 Combination of Enamine Catalysis and Lewis Acids in SN1-Type Reactions
26.6 Organocatalytic SN1-Type Reactions with Brønsted Acids
26.7 SN1-Type Reaction Promoted by Chiral Thioureas
26.8 SN1-Type Organocatalytic Reaction of Iminium, Oxonium, and Aziridinium Intermediates
26.9 Conclusions and Perspectives
27: Alpha-Heteroatom Functionalization of Carbonyl Compounds
27.1 Introduction
27.2 Enantioselective α-Pnictogenation of Carbonyl Compounds
27.3 Enantioselective α-Chalcogenation
27.4 Enantioselective α-Halogenation of Carbonyl Compounds
27.5 Summary and Conclusions
Part II: Nucleophile Addition to C=X Bonds
28: Aldol and Mannich-Type Reactions
28.1 Introduction
28.2 Enamine Catalysis
28.3 Brønsted Acid Catalysis Including Hydrogen-Bond Catalysis
28.4 Brønsted Base Catalysis Including Bifunctional Catalysis
28.5 Phase-Transfer Catalysis
28.6 N-Heterocyclic Carbene (NHC) Catalysis
28.7 Supported Organocatalysis
28.8 Summary and Conclusions
29: Additions of Nitroalkyls and Sulfones to C=X
29.1 Organocatalytic Addition of Nitroalkanes to C=O (The Henry Reaction)
29.2 Addition of Nitroalkanes to C=NR (The Aza-Henry or Nitro-Mannich Reaction)
29.3 Organocatalytic Addition of Sulfones to C=X
29.4 Summary and Outlook
30: Hydrocyanation and Strecker Reactions
30.1 Introduction
30.2 Amino-Acid Containing Catalysts for Carbonyl Hydrocyanation
30.3 Thiourea Catalysts for Carbonyl Hydrocyanation
30.4 C2-Symmetrical Guanidines and N,N′-Dioxides
30.5 Diketopiperazines as Catalysts for the Strecker Reaction
30.6 (Thio)urea Catalysts for the Strecker Reaction
30.7 Guanidines as Catalysts for the Strecker Reaction
30.8 N,N′-Dioxides and Bis-Formamides as Catalysts for the Strecker Reaction
30.9 Chiral Quaternary Ammonium Salts as Catalysts for the Strecker Reaction
30.10 BINOL-Phosphates as Catalysts for the Strecker Reaction
30.11 Other Catalysts for the Strecker Reaction
31: The Morita–Baylis–Hillman (MBH) and Hetero-MBH Reactions
31.1 Introduction
31.2 Recent Mechanistic Insights into the MBH/aza-MBH Reaction and Its Asymmetric Version
31.3 Recent Developments of Essential Components
31.4 Recent Developments of Asymmetric MBH/aza-MBH Reactions
31.5 Conclusions
32: Reduction of C=O and C=N
32.1 Introduction
32.2 Hantzsch Ester as the Hydride Source
32.3 Trichlorosilane as the Reducing Reagent
32.4 Other Hydrogen Sources
32.5 Summary and Conclusions
Part III: Nucleophile Addition to C=C Bonds
33: Addition to α,β-Unsaturated Aldehydes and Ketones
33.1 Introduction
33.2 Nucleophilic Addition to Enals and Ketones
33.3 Conclusion
34: Addition to Nitroolefins and Vinyl Sulfones
34.1 Introduction
34.2 Addition to Nitroolefins
34.3 Addition to Vinyl Sulfones
34.4 Addition to Vinyl Selenones
34.5 Summary and Conclusions
Acknowledgments
35: Organocatalyzed Asymmetric Arylation and Heteroarylation Reactions
35.1 Introduction
35.2 Representative Classes of Electrophiles
35.3 Friedel–Crafts in Organocascade Transformations
35.4 Application in Biologically Interesting and Natural Product Syntheses
35.5 Miscellaneous
35.6 Conclusion
Part IV: Ring-Forming Reactions
36: Intramolecular Reactions
36.1 Introduction
36.2 Intramolecular Ring-Forming Reactions via Covalent Catalysis
36.3 Intramolecular Ring-Forming Reactions by Non-Covalent Catalysis
36.4 Conclusion
37: Formation of 3-, 4- and 5-Membered Cycles by Intermolecular Reactions
37.1 Introduction
37.2 Organocatalytic Asymmetric Synthesis of Five-Membered Cycles
37.3 Organocatalytic Asymmetric Synthesis of Four-Membered Cycles
37.4 Organocatalytic Asymmetric Synthesis of Three-Membered Cycles
37.5 Conclusion
38: Diels-Alder and Hetero-Diels–Alder Reactions
38.1 Introduction
38.2 Organocatalytic Diels–Alder Reaction
38.3 Organocatalysis of Oxa-Hetero-Diels–Alder Reaction
38.4 Organocatalysis of Aza-Hetero-Diels–Alder Reaction
38.5 Conclusion
Part V: Increasing Complexity
39: Organocatalytic Radical and Electron Transfer Reactions
39.1 Introduction
39.2 Chemically Induced Oxidative Electron-Transfer Reactions
39.3 Photoredox Catalysis
39.4 Photochemical Asymmetric Synthesis
39.5 Conclusion
40: Organocatalytic Sigmatropic Reactions
40.1 Introduction
40.2 Steglich and Related Rearrangements
40.3 1,3-Sigmatropic Rearrangements
40.4 1,4-Sigmatropic Rearrangements
40.5 2,3-Sigmatropic Rearrangements
40.6 3,3-Sigmatropic Rearrangements
40.7 Aza-Petasis–Ferrier Rearrangement
40.8 Pinacol and Related Rearrangements
Acknowledgments
41: Regio- and Position Selective Reactions and Desymmetrizations
41.1 Introduction
41.2 Kinetic Resolution of Alcohols
41.3 Kinetic Resolution of Amines
41.4 Concluding Remarks
42: Three or More Components Reactions (Single Catalyst Systems)
42.1 General Introduction
42.2 Covalent Modes of Catalysis–Developing MCRs by Asymmetric Aminocatalysis
42.3 Non-Covalent Modes of Catalysis
42.4 Merging Covalent and Non-Covalent Activation Modes
42.5 Summary and Outlook
Acknowledgments
43: Multi-Catalyst Systems
43.1 Introduction
43.2 Combinational Use of Dual Brønsted Acids
43.3 Combinational Use of Chiral Brønsted Acid and Chiral or Achiral Lewis Base
43.4 Carbene-Based Dual Organocatalysis
43.5 Amino Catalyst-Based Cooperative Catalysis with Multifarious Co-Catalysts
43.6 Conclusions
Acknowledgments
44: Organocatalysis in Total Synthesis
44.1 Introduction
44.2 Aminocatalysis in Natural Product Synthesis
44.3 Hydrogen Bond Catalysis in Total Synthesis
44.4 Cinchona Alkaloids in Total Synthesis
44.5 Phase-Transfer Catalysis in Target Molecule Synthesis
44.6 Industrial Applications of Organocatalysis
44.7 Conclusions
Index
Related Titles
The Editor
Dr. Peter I. Dalko
Université Paris-Descartes
PRES Sorbonne Paris Cité, CNRS
45, rue des Saints-Pères
75270 Paris Cedex 06
France
Cover
© darknightsky – Fotolia.com
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
British Library Cataloguing-in-Publication Data
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 <http://dnb.d-nb.de>.
© 2013 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.
Composition Toppan Best-set Premedia Ltd., Hong Kong
Cover Design Schulz Grafik-Design, Fußgönheim
Print ISBN: 978-3-527-33236-6
ePDF ISBN: 978-3-527-65889-3
ePub ISBN: 978-3-527-65888-6
mobi ISBN: 978-3-527-65887-9
oBook ISBN: 978-3-527-65886-2
Foreword
The enthusiasm and dedication with which chemists have embraced the field of organocatalysis after its inauguration in 2000 has been spectacular and somewhat resembled the quick opening of a bottle of champagne under pressure. So much catalysis needed to be rapidly discovered and revealed by an ever increasing number of researchers with so little time. First dozens, soon hundreds and later thousands of publications appeared describing the power and potential of organic catalysis. But why did all those ideas and catalysis concepts appear in such a burst? In my opinion, the organocatalysis explosion was fueled by the deeper understanding of the reactivity of organic compounds, which chemists have accumulated during the last two centuries. Without doubt, in their slow but steady advancement, organic chemists significantly benefited from the inclusion of physical methods such as kinetics, theory, and spectroscopy. The new understanding had served them very well towards the sophistication of organic synthesis, enabling chemists to make many interesting and useful molecules and materials such as drugs, dyes, polymers, and natural products. But for some reason, this understanding had hardly been applied to advancing organic catalysis. The science of catalysis had been a domain of organometallic chemistry and possibly of biochemistry but certainly not of organic chemistry. Once the first examples of rationally designed reactions catalyzed by organic molecules were disclosed though, the situation quickly became an entirely different one. All of a sudden, the accumulated knowledge of the principles of organic reactivity could immediately be applied to the design of novel catalysis concepts. For organic chemists, entering the catalysis domain by facilely illustrating that organic compounds can be active and selective catalysts very much like metals and proteins was an exciting adventure.
Now, a dozen years later, the discovery phase of organocatalysis continues relentlessly but another phase is also beginning and that is the phase of understanding and structuring organocatalysis. I think these times are equally exciting and valuable for the field. For example, many mechanistic details are still to be elucidated, including the exact nature of reactive intermediates in organocatalysis. But for me, it is also time to define the logics of organocatalysis and to give the field a certain structure. In my experience, making the effort to classify and structure an area is highly rewarding as one can easily identify uninvestigated territories, which in turn are valuable windows of opportunities for further breakthrough research.
It appears to be in this spirit that the present book is edited. I think these efforts are highly laudable and the editor has tried very hard to organize organocatalysis in a rational manner. He also has put a lot of effort on identifying the leading people in the field and on recruiting them as authors. What a massive and impressive task! Efforts such as the present one are of great value in encouraging further studies from the next generation of chemists. I hope they will be stimulated to conduct exciting new research in areas where nobody else had been before, possibly opening up another bottle …
Ben List
Preface
This book is the new edition of the earlier published Enantioselective Organocatalysis manual, which appeared six years ago. Over the past six years the organocatalysis field has progressed considerably; many new more and more powerful methods were discovered, and a new edition of this book appeared to be necessary. The aim of this multiauthor book was to recollect efficient organocatalytic reactions around clear principles that meet actual standards in asymmetric synthesis. Chapters were written in a concise way, and this condensed treatment is supported by more than 1400 schemes and figures, providing condensed visual information at a glance. The book was kept updated with the literature until spring/summer 2012. Considering the historically broad interest in the field, the book wishes to address a large audience: academic or industrial researchers, students, and teachers who are interested in synthetic organic chemistry at an advanced level.
The difficulty of discussing organocatalytic reactions in a comprehensive way lies in the dichotomy of the catalyst/reaction approach: looking at the chemistry from the catalyst side, which is usually more suitable for researchers who are developing new reactions, or discussing the topic by reaction types, which is more useful for those who wish to apply these new reactions in synthesis. The book explores a novel type of treatment by merging different approaches (catalysts, activation types, and applications), giving readers an opportunity to examine the same transformation from different points of view, allowing for some overlaps between parts. In order to give the most useful insight into this large and fast progressing field, frontline leaders who pioneered the field of organocatalysis were requested to contribute to this work. I wish to acknowledge all of the 96 authors for participating in this venture despite their already heavy responsibilities, yielding a manual of a high standard. I wish also to acknowledge the important lecture and advice of many of my colleagues and friends who assisted me in the evaluation and correction process: I am indebted to Prof. Jose L. Vicario, Prof. Helma Wennemers, Prof. Ryan Gilmour, Prof. Viresh H. Rawal, Prof. Frank Glorius, Prof. Yoshiji Takemoto, Prof. Stephen Connon, Dr. Tirayut Vilaivan, Dr. Pablo Domínguez de María, Dr. Vinod Kumar Singh, and Prof. Jieping Zhu. Also, I wish to acknowledge the help and the professionalism of Dr. Anne Brennführer and Mrs Bernadette Anna Gmeiner of STM Books, Wiley-VCH Verlag GmbH & Co. KGaA, who worked tirelessly to keep all deadlines on time. I had a sincere pleasure to work on this project with you.
Peter I. Dalko
Paris, May 20, 2013
List of Contributors
Takahiko Akiyama
Gakushuin University
Department of Chemistry
1-5-1 Mejiro
Toshima-ku
Tokyo 171-8588
Japan
Łukasz Albrecht
Aarhus University
Department of Chemistry
Center for Catalysis
Langelandsgade 140
8000 Aarhus
Denmark
Jon C. Antilla
University of South Florida
Department of Chemistry
4202 East Fowler Avenue CHE205A
Tampa, FL 33613
USA
Alan Armstrong
Imperial College London
Department of Chemical Engineering and Chemical Technology and Department of Chemistry
South Kensington Campus
London SW7 2AZ
UK
Stellios Arseniyadis
ESPCI ParisTech
Laboratoire de Chimie Organique
CNRS (UMR 7084)
10 Rue Vauquelin
75231 Paris
France
Carlos F. Barbas III
The Scripps Research Institute
The Departments of Chemistry and Molecular Biology
10550 North Torrey Pines Road
La Jolla, CA 92037
USA
Stefan Bräse
Karlsruher Institut für Technologie (KIT)
Institut für Organische Chemie
Fritz-Haber-Weg 6
76131 Karlsruhe
Germany
Cyril Bressy
Aix-Marseille Université
Institut des Sciences Moléculaires de Marseille (iSm2)
CNRS – UMR 7313
Campus St Jérôme
Service 532
13397 Marseille
France
Jean-Marc Campagne
Ecole Nationale Supérieure de Chimie
ICGM-UMR 5253 (CNRS-ENSCM-UM2-UM1)
8 Rue de l'Ecole Normale
34296 Montpellier
France
Ying-Chun Chen
Sichuan University
West China School of Pharmacy
No. 17 3rd South Road Renming
Chengdu 610041
China
Xavier Companyó
Universitat de Barcelona
Departament de Química Orgànica
Gran Via de les Cortes
08028 Barcelona
Spain
Pier Giorgio Cozzi
Alma Mater Studiorum Università di Bologna
Dipartimento di Chimica “G. Ciamician”
Via Selmi 2
40126 Bologna
Italy
Marta Dal Molin
University of Padova
Department of Chemical Sciences
Via Marzolo 1
35131 Padova
Italy
Peter I. Dalko
Université Paris Descartes, PRES Sorbonne Paris Cité, CNRS
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques
45, rue des Saints-Pères
75270 Paris
France
Olivier R.P. David
Université de Versailles St-Quentin-en-Yvelines
Institut Lavoisier – UMR8180
45 avenue des Etats-Unis
78035 Versailles
France
Gustav Dickmeiss
Aarhus University
Department of Chemistry
Center for Catalysis
Langelandsgade 140
8000 Aarhus
Denmark
Kuiling Ding
Chinese Academy of Sciences
Shanghai Institute of Organic Chemistry
State Key Laboratory of Organometallic Chemistry
345 Lingling Road
Shanghai 200032
China
Haifeng Du
Chinese Academy of Sciences
Institute of Chemistry
CAS Key Laboratory of Molecular Recognition and Function
No. 2 1st North Street Zhongguancun
Beijing 100190
China
Krzysztof Dudziński
University of Warsaw
Faculty of Chemistry
Pasteura 1
02-093 Warsaw
Poland
Enrico Emer
Alma Mater Studiorum Università di Bologna
Dipartimento di Chimica “G. Ciamician”
Via Selmi 2
40126 Bologna
Italy
Roberto Fanelli
Università degli Studi dell'Insubria
Dipartimento di Scienza e Alta Tecnologia
Via Valleggio 11
22100 Como
Italy
Renata Marcia de Figueiredo
Ecole Nationale Supérieure de Chimie
ICGM-UMR 5253 (CNRS-ENSCM-UM2-UM1)
8 Rue de l'Ecole Normale
34296 Montpellier
France
Thibault Gallavardin
Université Paris Descartes, PRES Sorbonne Paris Cité
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques
45, rue des Saints-Pères
75270 Paris
France
Patrizia Galzerano
University of Padova
Department of Chemical Sciences
Via Marzolo 1
35131 Padova
Italy
Giulio Gasparini
University of Padova
Department of Chemical Sciences
Via Marzolo 1
35131 Padova
Italy
Francesco Giacalone
Sez. Chimica Organica “E. Paternò”
Dipartimento Scienze e Tecnologie Molecolari e Biomolecolari (STEMBIO)
Viale delle Scienze
Ed. 17
90128 Palermo
Italy
Michel Gravel
University of Saskatchewan
Department of Chemistry
110 Science Place
Saskatoon, SK S7N 5C9
Canada
Michelangelo Gruttadauria
Sez. Chimica Organica “E. Paternò”
Dipartimento Scienze e Tecnologie Molecolari e Biomolecolari (STEMBIO)
Viale delle Scienze
Ed. 17
90128 Palermo
Italy
Andrea Gualandi
Alma Mater Studiorum Università di Bologna
Dipartimento di Chimica “G. Ciamician”
Via Selmi 2
40126 Bologna
Italy
Gabriela Guillena
Universidad de Alicante
Departmento Química Orgánica e Instituto de Síntesis Orgánica
Campus de Sant Vicent del Raspeig
03080 Alicante
Spain
Tore Hansen
University of Oslo
Department of Chemistry
P. O. Box 1033 Blindern
0315 Oslo
Norway
Tatjana Heckel
University of Paderborn
Department of Chemistry
Organic Chemistry
Warburgerstr. 100
33098 Paderborn
Germany
Raquel P. Herrera
CSIC-Universidad de Zaragoza
Instituto de Síntesis Química y Catálisis Homogénea (ISQCH)
Departamento de Química Orgánica
Laboratorio de Síntesis Asimétrica
Plz de San Francisco s/n
50009 Zaragoza
Spain
Henk Hiemstra
University of Amsterdam
Van ‘t Hoff Institute for Molecular Sciences
Science Park 904
1098 XH Amsterdam
The Netherlands
Steen Ingemann
University of Amsterdam
Van ‘t Hoff Institute for Molecular Sciences
Science Park 904
1098 XH Amsterdam
The Netherlands
Gergely Jakab
Justus-Liebig University Giessen
Institute of Organic Chemistry
Heinrich-Buff-Ring 58
35392 Giessen
Germany
Kim L. Jensen
Aarhus University
Department of Chemistry
Center for Catalysis
Langelandsgade 140
8000 Aarhus
Denmark
Karl Anker Jørgensen
Aarhus University
Department of Chemistry
Center for Catalysis
Langelandsgade 140
8000 Aarhus
Denmark
Hao Jiang
Aarhus University
Department of Chemistry
Center for Catalysis
Langelandsgade 140
8000 Aarhus
Denmark
Pavel Kočovský
University of Glasgow
Department of Chemistry
University Avenue
Glasgow G12 8QQ
UK
Hiyoshizo Kotsuki
Kochi University
Faculty of Science
Laboratory of Natural Products Chemistry
Akebono-cho
Kochi 780-8520
Japan
Carsten Kramer
Karlsruher Institut für Technologie (KIT)
Institut für Organische Chemie
Fritz-Haber-Weg 6
76131 Karlsruhe
Germany
Tor Erik Kristensen
University of Oslo
Department of Chemistry
P. O. Box 1033 Blindern
0315 Oslo
Norway
Alexander S. Kucherenko
Zelinsky Institute of Organic Chemistry RAS
Leninsky prosp.
Moscow 119991
Russia
Piotr Kwiatkowski
University of Warsaw
Faculty of Chemistry
Pasteura 1
02-093 Warsaw
Poland
Aitor Landa
The University of the Basque Country (UPV-EHU)
Department of Organic Chemistry I
Manuel Lardizabal, 3
20018 Donostia-San Sebastián
Spain
Guilong Li
University of South Florida
Department of Chemistry
4202 East Fowler Avenue CHE205A
Tampa, FL 33613
USA
Saihu Liao
Shanghai Institute of Organic Chemistry
State Key Laboratory of Organometallic Chemistry
345 Lingling Lu
Shanghai 200032
China
Rosa López
The University of the Basque Country (UPV-EHU)
Department of Organic Chemistry I
Manuel Lardizabal, 3
20018 Donostia-San Sebastián
Spain
Yixin Lu
Hangzhou Normal University
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education
Hangzhou 310012
China
and
National University of Singapore
Department of Chemistry
3 Science Drive 3
Singapore 117543
Republic of Singapore
Dawid Łyżwa
University of Warsaw
Faculty of Chemistry
Pasteura 1
02-093 Warsaw
Poland
Rainer Mahrwald
Humboldt-University
Institute of Chemistry
Brook-Taylor Str. 2
12489 Berlin
Germany
Andrei V. Malkov
University of Glasgow
Department of Chemistry
University Avenue
Glasgow G12 8QQ
UK
and
Loughborough University
Department of Chemistry
Loughborough LE11 3TU
UK
Eugenia Marqués-López
CSIC-Universidad de Zaragoza
Instituto de Síntesis Química y Catálisis Homogénea (ISQCH)
Departamento de Química Orgánica
Laboratorio de Síntesis Asimétrica
Plz de San Francisco s/n
50009 Zaragoza
Spain
Keiji Maruoka
Kyoto University
Graduate School of Science
Department of Chemistry
Sakyo
Kyoto 606-8502
Japan
Nobuyuki Mase
Shizuoka University
Department of Molecular Science
Faculty of Engineering
3-5-1 Johoku
Naka-ku
Hamamatsu 432-8561
Japan
Paolo Melchiorre
ICIQ – Institute of Chemical Research of Catalonia
Avenida Països Catalans 16
43007 Tarragona
Spain
and
ICREA – Institució Catalana de Recerca i Estudis Avançats
Passeig Lluís Companys 23
08010 Barcelona
Spain
Harry J. Milner
Imperial College London
Department of Chemical Engineering and Chemical Technology and Department of Chemistry
South Kensington Campus
London SW7 2AZ
UK
Antonio Moran
ICIQ – Institute of Chemical Research of Catalonia
Avenida Països Catalans 16
43007 Tarragona
Spain
Keiji Mori
Gakushuin University
Department of Chemistry
1-5-1 Mejiro
Toshima-ku
Tokyo 171-8588
Japan
Albert Moyano
Universitat de Barcelona
Facultat de Química
Departament de Química Orgànica
C. Martí i Franquès 1-11
08028-Barcelona
Catalonia
Spain
Kohsuke Ohmatsu
Nagoya University
Graduate School of Engineering
Department of Applied Chemistry
Furo B2-3(611)
Nagoya 464-8603
Japan
Mikel Oiarbide
The University of the Basque Country (UPV-EHU)
Department of Organic Chemistry I
Manuel Lardizabal, 3
20018 Donostia-San Sebastián
Spain
Takashi Ooi
Nagoya University
Graduate School of Engineering
Department of Applied Chemistry
Furo B2-3(611)
Nagoya 464-8603
Japan
Claudio Palomo
The University of the Basque Country (UPV-EHU)
Department of Organic Chemistry I
Manuel Lardizabal, 3
20018 Donostia-San Sebastián
Spain
Hélène Pellissier
Aix-Marseille Université
UMR CNRS n° 6263
Equipe Chirosciences
Case 561
Avenue Esc. Normandie-Niemen
13397 Marseille
France
Diego Petruzziello
Alma Mater Studiorum Università di Bologna
Dipartimento di Chimica “G. Ciamician”
Via Selmi 2
40126 Bologna
Italy
Umberto Piarulli
Università degli Studi dell'Insubria
Dipartimento di Scienza e Alta Tecnologia
Via Valleggio 11
22100 Como
Italy
Leonard J. Prins
University of Padova
Department of Chemical Sciences
Via Marzolo 1
35131 Padova
Italy
Viresh H. Rawal
The University of Chicago
Department of Chemistry
5735 S Ellis Avenue
Chicago, IL 60637
USA
Ramon Rios
Universitat de Barcelona
Departament de Química Orgànica
Gran Via de les Cortes
08028 Barcelona
Spain
and
ICREA
Passeig Lluis Companys
23
08010 Barcelona
Spain
Christèle Roux
Aix-Marseille Université
Institut des Sciences Moléculaires de Marseille (iSm2)
CNRS – UMR 7313
Campus St Jérôme
Service 532
13397 Marseille
France
Eduardo Sánchez-Larios
University of Montreal
Department of Chemistry
C.P. 6128
succursale Centre-ville
Montréal, QC H3C 3J7
Canada
Niiha Sasakura
Kochi University
Faculty of Science
Laboratory of Natural Products Chemistry
Akebono-cho
Kochi 780-8520
Japan
Scott E. Schaus
Boston University
Department of Chemistry
590 Commonwealth Avenue
Boston, MA 02215
USA
Peter R. Schreiner
Justus-Liebig University Giessen
Institute of Organic Chemistry
Heinrich-Buff-Ring 58
35392 Giessen
Germany
Zhihui Shao
Yunnan University
School of Chemical Science and Technology
Ministry of Education
Key Laboratory of Medicinal Chemistry for Natural Resource
Kunming 650091
China
Min Shi
Chinese Academy of Sciences
Shanghai Institute of Organic Chemistry
State Key Laboratory of Organometallic Chemistry
354 Fenglin Road
Shanghai 200032
China
Seiji Shirakawa
Kyoto University
Graduate School of Science
Department of Chemistry
Sakyo
Kyoto 606-8502
Japan
Dmitry E. Siyutkin
Zelinsky Institute of Organic Chemistry RAS
Leninsky prosp.
Moscow 119991
Russia
Alan C. Spivey
Imperial College
Department of Chemistry
South Kensington Campus
London SE7 2AZ
UK
Raghavan B. Sunoj
Indian Institute of Technology Bombay
Department of Chemistry
Powai
Mumbai 400076
India
Yong Tang
Shanghai Institute of Organic Chemistry
State Key Laboratory of Organometallic Chemistry
345 Lingling Lu
Shanghai 200032
China
René Tannert
ICIQ – Institute of Chemical Research of Catalonia
Avenida Països Catalans 16
43007 Tarragona
Spain
Karen Thai
University of Saskatchewan
Department of Chemistry
110 Science Place
Saskatoon, SK S7N 5C9
Canada
Amal Ting
Catabasis Pharmaceuticals Inc.
One Kendall Square
Cambridge, MA 02139
USA
Christine Tran
Université Paris Descartes, PRES Sorbonne Paris Cité
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques
45, rue des Saints-Pères
75270 Paris
France
Yunus E. Türkmen
The University of Chicago
Department of Chemistry
5735 S Ellis Avenue
Chicago, IL 60637
USA
Daisuke Uraguchi
Nagoya University
Graduate School of Engineering
Department of Applied Chemistry
Furo B2-3(611)
Nagoya 464-8603
Japan
Guillem Valero
Universitat de Barcelona
Facultat de Química
Departament de Química Orgànica
C. Martí i Franquès 1-11
08028-Barcelona
Catalonia
Spain
Peng Wang
Shanghai Institute of Organic Chemistry
State Key Laboratory of Organometallic Chemistry
345 Lingling Lu
Shanghai 200032
China
Yin Wei
Chinese Academy of Sciences
Shanghai Institute of Organic Chemistry
State Key Laboratory of Organometallic Chemistry
354 Fenglin Road
Shanghai 200032
China
René Wilhelm
University of Paderborn
Department of Chemistry
Organic Chemistry
Warburgerstr. 100
33098 Paderborn
Germany
You-Cai Xiao
Sichuan University
West China School of Pharmacy
No. 17 3rd South Road Renming
Chengdu 610041
China
Li-Wen Xu
Hangzhou Normal University
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education
No. 222, Wenyi Road
Hangzhou 310012
China
Huameng Yang
Hangzhou Normal University
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education
No. 222, Wenyi Road
Hangzhou 310012
China
Ye Zhu
The University of Chicago
Department of Chemistry
5735 S Ellis Avenue
Chicago, IL 60637
USA
Sergei G. Zlotin
Zelinsky Institute of Organic Chemistry RAS
Leninsky prosp.
Moscow 119991
Russia
Abbreviations
Part I
Amino Acid-Derived Catalysts
1
Proline-Related Secondary Amine Catalysts and Applications
Hiyoshizo Kotsuki and Niiha Sasakura
1.1 Introduction
Since the reappearance of L-proline (1) at the forefront of organocatalysis, tremendous efforts have been made to devise new catalysts based on a proline core structure. In this field, the chirality of a pyrrolidine fragment plays a critical role, and the principal concept that underlies the development of new catalysts can be simply explained as the attachment of acidic sites in place of a carboxylic acid group to the side chain. Accordingly, several catalysts with various acidic functionalities have been developed [1]. In general, proline-based organocatalysts can be classified into six major categories: (A) prolinamides, (B) prolinamines, (C) proline tetrazoles, (D) prolinamine sulfonamides, (E) prolinamine thioureas, and (F) diarylprolinols (Figure 1.1). Representative pKa values of these catalysts are listed in Figure 1.2 [2]. A subtle change in the side-chain assembly may change the pKa value in the range 8–20, which would have a significant effect on the strength of hydrogen bonding, and thus the catalytic activity and selectivity may be affected.
Figure 1.1 Major classes of proline-based organocatalysts.
Figure 1.2 pKa values of representative proline-related compounds (in DMSO).
In this chapter we will deal with organocatalytic asymmetric transformations using these catalysts, mainly focusing on the significant and major achievements in this area published from 2000 to 2011. However, due to space constraints, this chapter will not cover the great utility of diarylprolinol catalysts (category F); for convenience, only references are given [3].
1.2 Prolinamide and Related Catalysts
Owing to the ready availability of prolinamide derivatives through the condensation of proline with amines, prolinamide-based compounds constitute a large family of organocatalysts [4]. Figure 1.3 lists representative examples of these catalysts.
Figure 1.3 Representative examples of prolinamide organocatalysts.
These catalysts are very useful in a wide range of asymmetric syntheses. Asymmetric aldol reactions have been investigated by several research groups; selected examples are compiled in Scheme 1.1.
Scheme 1.1
In this context, prolinamide 2 [5–8] and its aryl-substituted homologs such as 3–5 have been developed [9–14]. Analogous to these examples, binaphthyldiamine-derived compounds such as 6 and 7 have been introduced for use in aqueous systems and as recoverable catalysts [15–18]. For example, Benaglia and coworkers reported that the prolinamide catalyst 7 with a lipophilic side chain showed efficient catalytic activity in water [16b]. Chiral spiro diamine-derived catalysts have also been designed, albeit in moderate enantioselectivity [19]. Owing to the increased acidity of an NH group of thioamide relative to a normal amide, proline-thioamide catalysts such as 8 have been shown to be more effective [20–23].
A successful approach in this field is the design of multifunctionalized catalysts such as 9 and 10 through the incorporation of chiral aminoalcohol and related species onto the side chain [24–35]. The high catalytic activity and enantioselectivity of catalyst 9 can be explained by considering the favorable assembly of donor and acceptor molecules via double hydrogen-bonding stabilization, as depicted in the transition state model 15 [24h]. In these examples, to gain satisfactory results, it is important to match the chirality between the proline core and the attachment.
Several other related systems containing a prolinamide or proline-thioamide core have also been reported [36–42].
In some cases, a chiral diamine assembly can serve as an effective scaffold for the design of multiply functionalized catalysts like 11 and 12 [43–49]. Proline hydrazides [50], dipeptides [51–57], or other small peptides [58–63] bearing a prolinamide core have been shown to be useful in asymmetric aldol reactions.
Catalyst 13 was introduced for use in aqueous systems in the presence of surfactant Brønsted acids as co-catalysts [64], and several other catalysts such as 14 containing a heteroaromatic system have also been reported [65–67].
There has been important progress in the use of proline sulfonamides (pKa = 8–11) [2] as efficient organocatalysts, and Yang and Carter provided an excellent review [68]. Therefore, only a few important aspects are addressed here. Figure 1.4 lists representative examples of these catalysts.
Figure 1.4 Representative examples of proline sulfonamide organocatalysts.
Various N-arylsulfonyl-substituted prolinamides such as 16 have been used in asymmetric aldol reactions [69–78]. Carter and coworkers actively sought new efficient catalysts of this type, and found that 17 could serve as an efficient catalyst for asymmetric aldol reactions, even in the absence of any organic solvent, with excellent diastereo- and enantioselectivity (Scheme 1.2) [79].
Scheme 1.2
Recently, Ellman and coworkers have shown that chiral sulfinate 18 can catalyze asymmetric aldol reactions of acetone, whereas proline (1) itself gave poor results [80]. Nakamura and coworkers also explored this field, and found that 19 can promote the asymmetric cross-aldol reaction of acetone with activated ketones, to generate a quaternary carbon stereogenic center bearing an OH function [81].
With regard to aldol chemistry, Mannich or domino-Mannich–Michael reactions can also be promoted by N-arylsulfonyl-substituted prolinamide catalysts such as 17 with high levels of enantioselectivity [82, 83].
Importantly, prolinamide catalysts work well in Michael addition reactions using nitroolefins as acceptors [58, 64, 84–95]. For example, Nájera and coworkers used bifunctional catalyst 20 by virtue of the synergistic effect of double hydrogen-bonding activation, as depicted in the transition state model 21 (Scheme 1.3) [90]. For the same purpose, prolinamides containing a heteroaromatic system like 14 have also been reported [96].
Scheme 1.3
Analogously to these examples, proline-derived peptide catalysts can also efficiently promote Michael addition reactions [97–99]. Prolinamide or prolyl sulfonamide catalysts are also effective for intramolecular Michael addition reactions [100–102]. Recently, Yang and Carter reported a short-cut strategy to construct an all-carbon substituted quaternary carbon stereogenic center on a cyclohexenone framework via Robinson-type annulation using the 17-type catalyst (Scheme 1.4) [103].
Scheme 1.4
While some examples of prolinamide-catalyzed enantioselective Biginelli condensation [104, 105] and other types of C–C bond formation [106, 107] are known, their synthetic utility is unclear. Finally, for convenience, with regard to asymmetric heteroatom functionalization and transfer hydrogenation using prolinamides as catalysts, only references are given [108–114].
1.3 Prolinamine and Related Catalysts
Among several organocatalysts derived from L-proline (1) as a chiral source, pyrrolidine–tertiary amine conjugates constitute a powerful and useful family in asymmetric synthesis [115]. In 1994, Kawara and Taguchi reported pioneering work on the use of such catalysts in asymmetric Michael addition reactions [116]. Since then, several related catalysts have been developed. Figure 1.5 lists representative examples.
Figure 1.5 Representative examples of prolinamine organocatalysts.
In 2001, after screening several chiral diamines and protonic acid additives, Yamamoto and coworkers reported that a TfOH salt of 22 could efficiently promote asymmetric aldol reactions [117]. Thereafter, similar studies using chiral diamines such as 22–24 with Brønsted or Lewis acid additives have also been reported [118–122]. In 2006, the Mase/Takabe/Barbas groups discovered that prolinamine catalyst 25 with a lipophilic side chain showed efficient catalytic activity in water (Scheme 1.5) [123]. Thus, cyclohexanone reacts smoothly with various aldehydes in water to afford the desired aldol products in high yields with excellent diastereo- and enantioselectivity. Recently, the recyclability of analogous catalysts has been reported by others [124].
Scheme 1.5
Prolinamine catalyst 26 has been introduced for the same purpose [125].
With regard to asymmetric aldol reactions, it has been shown that prolinamine catalysts such as 22 can also work well for intramolecular aldol [126–128], Henry (nitroaldol) [129], Mannich [130, 131], and domino-Michael–aldol reactions [132] as valuable asymmetric transformations.
Similar to aldol chemistry, prolinamine-catalyzed asymmetric Michael addition reactions have attracted considerable attention from synthetic chemists, and successful examples have been developed (Scheme 1.6).
Scheme 1.6
In this field, prolinamine catalysts 22 and 24 are particularly useful for promoting asymmetric Michael addition reactions between several donor and acceptor molecules [120b, 133–136]. On a related topic, catalyst 27 and related diamine or triamine catalysts have been developed [137–139]. Interestingly, the Mase/Takabe/Barbas groups reported that diamine catalyst 25 could again serve as an efficient catalyst for asymmetric Michael addition reactions even in brine solution [140]. Similarly, several types of water-active catalysts such as 26 have been developed [141, 142].
Independently, Alexakis and coworkers reported that 2,2′-bipyrrolidine catalyst 28 showed excellent catalytic activity in several types of asymmetric Michael addition reactions [143]. It has been postulated that the isopropyl group on one of the C2-symmetric pyrrolidine rings should block not only the back face against the approach of Michael acceptors but also shift the equilibrium towards one of the two rotamers. Since then, closely related catalysts have also been reported [144]. Furthermore, different types of catalysts such as 29 have been shown to be useful in asymmetric Michael addition reactions [145–148].
While catalyst 22/23 has been known to be valuable in other C–C bond-forming strategies, for example, 1,3-dipolar cycloaddition [149], hetero-Diels–Alder reaction [150], Friedel–Crafts-type alkylation [151], double-Michael reaction [152], [2,3]-Wittig rearrangement [153], and Claisen–Schmidt condensation [154], only references are given here.
Finally, while various reactions under the catalysis of 22 or 24, for example, asymmetric epoxidation of α,β-unsaturated aldehydes [155], β-hydroalkoxylation of α,β-unsaturated enones [156], and stereoselective reduction of α,β-unsaturated enones (Scheme 1.7) [157], have also been reported, they have been demonstrated in only a limited number of experiments.
Scheme 1.7
1.4 Proline Tetrazole and Related Catalysts
Proline tetrazole catalysts (category C in Figure 1.1) are readily accessible from L-proline (1) [158]. They are remarkably useful in asymmetric synthesis [159]. As shown in Figure 1.2, the pKa of tetrazole is very similar to that of carboxylic acid. Moreover, the advantage of tetrazole catalysts is their robust and lipophilic nature compared to L-proline (1) itself, which allows them to escape parasitic bicyclo-oxazolidinone formation [160].
In 2004, Yamamoto and Arvidsson independently reported the catalytic activity of the L-proline tetrazole catalyst 30 in asymmetric aldol reactions of ketones with aldehydes [161–163]. At the same time, Ley and coworkers reached similar conclusions by applying this system to asymmetric Mannich and Michael addition reactions (Scheme 1.8) [164]. Since then, the scope of this chemistry has been expanded by several research groups [165–174].
Scheme 1.8
Ley and coworkers have been quite active in this field, and have found that 30 or its homolog could efficiently promote asymmetric Michael addition reactions using various Michael acceptors and donors [164b, 175]. In these cases, the reactions require the use of a basic amine such as trans-4,5-dimethylpiperazine as a co-catalyst to increase the nucleophilicity of donor molecules by deprotonation. Typical examples are shown in Scheme 1.9.
Scheme 1.9
A mechanistic investigation of this chemistry using density functional theory calculations [176] and reactions in ionic liquids as solvents have also been reported [177].
Interestingly, the Michael addition reaction of bromonitromethane to cyclic or acyclic enones constitutes a convenient way of preparing cyclopropane ring compounds in moderate to good enantioselectivity (Scheme 1.10) [178].
Scheme 1.10
Very similar results have also been reported with the use of sulfur ylides as donor molecules [179]. With regard to the asymmetric Biginelli reaction [180] and multicomponent coupling reactions [181] using 30 or its analog as a catalyst, only references are given here.
Finally, we should emphasize the synthetic utility of the 30-catalyzed α-oxidation of carbonyl compounds via an “O-nitroso aldol reaction” [182]. This method is very attractive as a metal-free oxidation system. For example, Yamamoto and coworkers found that aminoxylation reactions of ketones or aldehydes proceed with almost perfect enantioselectivities (97–99% ee) in the presence of 30 as a catalyst (Scheme 1.11) [183]. Mechanistically, nitroso compounds possess two electrophilic centers, that is, nitrogen and oxygen atoms, but the exclusive formation of O-alkylation products indicates that a hydrogen-bonding transition state like 31 seems to be satisfactorily stabilized with the more basic nitrogen atom. As an extension of this strategy, asymmetric domino-Michael–aldol reactions have also been developed by these authors, and these provide a convenient way to prepare 3-oxa-2-aza-bicycloketone derivatives in high enantioselectivity [184].
Scheme 1.11
Since then, extensive efforts have been made to apply this method to other multiple functionalizations [185–189] or to discover other possible oxidizing agents such as N-sulfonyloxaziridines [190]. As a related chemistry, asymmetric amination at the α-position of a carbonyl compound has also been reported with the use of azodicarboxylate esters as electrophiles [187c, 191–194]. Ley and coworkers have developed an ingenious strategy for obtaining chiral dihydropyridazine derivatives by the combination of asymmetric α-amination and Wittig olefination in a one-pot operation (Scheme 1.12) [187c, 192a].
Scheme 1.12
As a different family of heteroaromatic-substituted organocatalysts, imidazole- and triazole-based compounds have been known to be quite effective for asymmetric aldol and Michael addition reactions. Figure 1.6 lists representative examples of these catalysts.
Figure 1.6 Representative examples of proline-based heterocyclic organocatalysts.
The utility of ionic liquid conjugate catalysts such as 32 and 33 can be ascribed to their recyclability [195–199]. On the other hand, triazole-based catalysts such as 34 and 35 are readily accessible via Huisgen 1,3-dipolar cycloadditions, so-called “click reactions,” from azidomethyl-pyrrolidine and acetylenic precursors, and hence make it possible to design new immobilized catalysts [200–207].
Interestingly, it has been shown that the 33-catalyzed asymmetric SN1-type α-alkylation of aldehydes or ketones proceeds well in excellent diastereoselectivity and good enantioselectivity (Scheme 1.13) [208].
Scheme 1.13
1.5 Prolinamine Sulfonamide and Related Catalysts
Prolinamine sulfonamide catalysts (category D in Figure 1.1) can be envisaged as a reversal of prolinamides (A), and constitute a fascinating group of organocatalysts. The catalytic activity of these compounds can be ascribed simply to the sufficient acidity (pKa = 10) of a sulfonamide key structure (Figure 1.2). Figure 1.7 lists representative examples of these catalysts.
Figure 1.7 Further representative examples of prolinamine sulfonamide organocatalysts.
For example, in 2004, Wang and coworkers reported a series of asymmetric transformations, for example, α-aminoxylation, Mannich reactions, and α-sulfenylation, under the catalysis of pyrrolidine trifluoromethanesulfonamide 36; the product yields and diastereo- and enantioselectivities are quite good in most cases [209–211]. The proposed mechanism is essentially the same as that in the case of tetrazole catalyst 30 (Scheme 1.14); in contrast to the planar nature of a tetrazole in 30, a trifluoromethanesulfonyl group in 36 is non-planar. This difference may change the stability of a hydrogen-bonding network at the transition state.
Scheme 1.14
After these reports, the same group extended the utility of this catalytic system to asymmetric Michael addition and aldol reactions [212, 213]. Sulfonamide catalysts such as 37–39 have also been developed for the same purpose [214–219]. The behavior of these catalysts, typically exemplified by enantioselective Michael addition reactions of cyclohexanone with nitroolefins, is compiled in Scheme 1.15.
Scheme 1.15
With regard to the asymmetric α-amination of carbonyl compounds using pyrrolidine sulfonamides as catalysts, only references are given here [220, 221].
1.6 Prolinamine Thiourea and Related Catalysts
Prolinamine thiourea catalysts (category E, Figure 1.1) have been introduced primarily for the purpose of designing new bifunctional catalysts by connecting a pyrrolidine base with a remote hydrogen-bonding thiourea function [222]. Figure 1.8 lists representative examples of these catalysts.
Figure 1.8 Representative examples of prolinamine thiourea conjugates and related organocatalysts.
For example, Tang and coworkers found that bifunctional thiourea catalyst 40 could efficiently promote the asymmetric Michael addition reactions of ketones or α-branched aldehydes with various Michael acceptors (Scheme 1.16) [223]. In particular, the driving force in the present system can be ascribed to the strong hydrogen bond-forming character of thiourea with nitroolefin acceptors, as depicted in the transition state model 46.
Scheme 1.16
Since then, extensive efforts have been made to devise new powerful catalysts such as 41–43 through the modification of a key element of 40, albeit in most cases with similar or less efficiency [224–231]. Guanidinyl catalysts such as 44 and 45 have been developed to realize the conjugate addition reaction of malonates or nitroalkanes to α,β-unsaturated enones in high enantioselectivity, although the number of experiments has been limited (Scheme 1.17) [232, 233]. A plausible mechanism to account for the (S)-configuration of the major products can be ascribed to the transition state model 47.
Scheme 1.17
Finally, it has been shown that thiourea-type bifunctional catalysts are also useful for asymmetric aldol reactions [234, 235] and α-chlorination of aldehydes [236]. Furthermore, 4-substituted bifunctional analogs have been developed for use in anti-selective Mannich reactions [237].
1.7 Miscellaneous
As described so far, various pyrrolidine-based chiral organocatalysts open the door to a remarkably fruitful world of synthetic chemistry. In general, the synthetic protocol used to design new catalysts relies on the naturally occurring chiral source L-proline (1) as a key component. This should be a reasonable approach to achieving final success by mimicking “nature.” To characterize newly designed organocatalysts, carbonyl group functionalization, typically through Michael addition and aldol reactions, seems to be the easiest and most useful approach. These transformations are initially driven by the condensation of carbonyl compounds with a chiral pyrrolidine secondary amine to reversibly form iminium-enamine intermediates, but relatively low enantioselectivities were observed in aldol reactions catalyzed by proline ester congeners [238], except in the case of Loh's catalysts [239]. Hence, several different types of proline-related organocatalysts have been developed. Figure 1.9 lists representative examples of these catalysts.
Figure 1.9 Various types of proline-related organocatalysts.
For example, in 2003, Melchiorre and Jørgensen reported that the enantioselective Michael addition reaction of aldehydes with vinyl ketones proceeded efficiently in the presence of 48 as a catalyst (yield up to 93%, ee up to 85%) [240]. In our research laboratory, we have also been very interested in devising new catalysts with a pyridine ring as a rigid planar base adjacent to a pyrrolidine chiral ring. Along these lines, a series of new catalysts (49), that is, DPYMP [49a] and PPYMP [49b], were prepared from L-prolinol, and we found that they showed excellent catalytic activity in terms of productivity, diastereoselectivity, and enantioselectivity (Scheme 1.18) [241]. The results can be explained by invoking the transition state model 55, in which the pyridinium ring must effectively shield the Si-face of an enamine double bond.
Scheme 1.18
For the same purpose, various chiral pyrrolidine catalysts such as 50–54 have also been introduced [242–250]. The versatile nature of pyrrolidine catalysts has been recognized by other transformations: aldol reaction [251], Mannich-type reaction [252, 253], and oxa-Michael reaction [254]. Among these, Maruoka's work on anti-selective Mannich reactions is noteworthy (Scheme 1.19, compare with Scheme 1.8) [253]. In this case, the remote hydrogen-bonding form 57 derived from catalyst 56 can overcome the steric preference so that the opposite sense of stereochemistry should be observed.
Scheme 1.19
In 2003, Juhl and Jørgensen found that, after screening a series of pyrrolidine catalysts, catalyst 48 is again of great value for the inverse-electron-demand hetero-Diels–Alder reaction: after pyridinium chlorochromate (PCC) oxidation, lactone products could be obtained as a single diastereomer in excellent enantioselectivity (Scheme 1.20) [255]. The proposed transition state model 58 indicates effective shielding of the Si-face of the enamine double bond by the diarylmethyl substituent on the pyrrolidine ring of the catalyst.
Scheme 1.20
A closely related study has also been reported with the use of a 53-type catalyst [256].
Finally, another set of pyrrolidine-derived organocatalysts is listed in Figure 1.10.
Figure 1.10 Miscellaneous examples of pyrrolidine-based organocatalysts.
In 2004, Jørgensen and coworkers reported that the asymmetric α-chlorination of aldehydes proceeds well in the presence of C2-symmetric diphenylpyrrolidine (59) as a catalyst using N-chlorosuccinimide (NCS) as a chlorinating agent [257]. Thereafter, they also explored its applicability to fluorination (48-type catalyst) and bromination (Scheme 1.21) [258].
Scheme 1.21
The synthetic utility of this method is clear: it provides easy manipulation of the products to give various important chiral building blocks such as chlorohydrins, epoxides, aziridines, amino acids, and amino alcohols [257–259], and is readily applicable to natural product synthesis [260].
Recently, considerable efforts have been made to discover new organocatalytic systems for asymmetric epoxidation. In 2003, Aggarwal and coworkers reported that the asymmetric epoxidation of olefins proceeded in good yields and with moderate enantioselectivities using Oxone® (Wako Chemicals, Osaka, Japan) as an oxidant in the presence of a 48-type catalyst (Scheme 1.22) [261]. According to their proposal, the protonated ammonium salt species can act not only as a phase-transfer catalyst to carry the real oxidant species to the organic phase but also as a promoter to activate the chiral oxidant via hydrogen-bonding stabilization, as depicted in 63.
Scheme 1.22
On the other hand, Maruoka and coworkers achieved the asymmetric α-benzoyloxylation of aldehydes using the newly designed catalyst 60 (Scheme 1.23) [262].
Scheme 1.23
Novel catalysts 61 and 62 have been invented to increase the catalytic activity by incorporation of an electronegative group (fluorine or azido) at the β-position relative to the NH group: an electrostatic interaction (or gauche-effect) between those groups might be favorable for stabilizing reactive intermediates [263–266]. For example, Gilmour and coworkers reported the 61-catalyzed asymmetric epoxidation of α,β-unsaturated aldehydes (Scheme 1.24) [265].
Scheme 1.24
On the other hand, Zhong and coworkers found that the 62-catalyzed system was effective for enantioselective [4+1]-annulation using 2-nitroacrylates and α-iodoaldehydes, to form cis-isoxazoline N-oxide derivatives in high yields and in high diastereo- and enantioselectivity (Scheme 1.25) [266].
Scheme 1.25
1.8 Conclusions
As described above, a great deal of success has been achieved in a wide variety of asymmetric transformations using a series of proline-related organocatalysts. This organocatalytic asymmetric synthesis offers several advantages over metal-catalyzed systems; for example, the ready availability of both enantiomers, ease of handling without the need for an inert atmosphere or anhydrous conditions, and inexpensive and non-toxic reagents. Unfortunately, however, significant limitations still remain to be overcome in this field, including high catalyst loading, a long reaction period, and harmful organic solvent media. We hope that this exceedingly attractive field in modern organic chemistry can lead to new, much more powerful catalysts as well as highly efficient organocatalyst-based asymmetric transformations.
Acknowledgments
The authors would like to acknowledge the past and present members of their research group for their enthusiastic contributions in the field of organocatalysis. The authors also thank Professors Y. Ichikawa and K. Nakano for fruitful discussions and encouragement. Our research project in this field was supported in part by the Yamada Science Foundation, and by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) in Japan (No. 24105523). One of the authors (N.S.) is grateful for a Sasakawa Scientific Research Grant from the Japan Science Society.
References
1 Selected reviews: (a) Guillena, G., Nájera, C., and Ramón, D.J. (2007) Tetrahedron: Asymmetry, 18, 2249; (b) Kotsuki, H., Ikishima, H., and Okuyama, A. (2008), Heterocycles, 75, 493; (c) Kotsuki, H., Ikishima, H., and Okuyama, A. (2008) Heterocycles, 75, 757; (d) Panday, S.K. (2011) Tetrahedron: Asymmetry, 22, 1817.
2 Bordwell, F.G. (1988) Acc. Chem. Res., 21, 456; (b) Huang, X.-Y., Wang, H.-J., and Shi, J. (2010) J. Phys. Chem. A, 114, 1068.
3 Selected reviews: (a) Palomo, C. and Mielgo, A. (2006) Angew. Chem., Int. Ed., 45, 7876; (b) Mielgo, A. and Palomo, C. (2008) Chem. Asian J., 3, 922; (c) Bertelsen, S. and Jørgensen, K.A. (2009) Chem. Soc. Rev., 38, 2178; (d) Lattanzi, A. (2009) Chem. Commun., 1452; (e) Xu, L.-W., Li, L., and Shi, Z.-H. (2010) Adv. Synth. Catal., 352, 243; (f) Valero, G., Companyó, X., Bravo, N., Alba, A.-N.R., Moyano, A., and Rios, R. (2010) Synlett, 1883.
4 Reviews: (a) Liu, X., Lin, L., and Feng, X. (2009) Chem. Commun., 6145; (b) Chen, X.-H., Yu, J., and Gong, L.-Z. (2010) Chem. Commun., 46, 6437.
5 (a) Samanta, S. and Zhao, C-G. (2006), Tetrahedron Lett., 47, 3383; (b) Samanta, S. and Zhao, C-G. (2006) J. Am. Chem. Soc., 128, 7442; (c) Dodda, R. and Zhao, C.-G. (2006) Org. Lett., 8, 4911.
6 Zhang, F., Su, N., and Gong, Y. (2006) Synlett, 1703.
7 Aratake, S., Itoh, T., Okano, T., Usui, T., Shoji, M., and Hayashi, Y. (2007) Chem. Commun., 2524.
8 Zhang, X.-M., Wang, M., Tu, Y.-Q., Fan, C.-A., Jiang, Y.-J., Zhang, S.-Y., and Zhang, F.-M. (2008) Synlett, 2831.
9 (a) Chimni, S.S., Mahajan, D., and Suresh Babu, V.V. (2005) Tetrahedron Lett., 46, 5617; (b) Chimni, S.S. and Mahajan, D. (2006) Tetrahedron: Asymmetry, 17, 2108; (c) Chimni, S.S., Singh, S., and Mahajan, D. (2008) Tetrahedron: Asymmetry, 19, 2276; (d) Chimni, S.S., Singh, S., and Kumar, A. (2009) Tetrahedron: Asymmetry, 20, 1722.
10 He, L., Tang, Z., Cun, L.-F., Mi, A.-Q., Jiang, Y.-Z., and Gong, L.-Z. (2006) Tetrahedron, 62, 346.
11 Xiong, Y., Wang, F., Dong, S., Liu, X., and Feng, X. (2008) Synlett, 73.
12 Li, X.-J., Zhang, G.-W., Wang, L., Hua, M.-Q., and Ma, J.-A. (2008) Synlett, 1255.
13 Moorthy, J.N. and Saha, S. (2009) Eur. J. Org. Chem., 739.
14 Xu, J., Fu, X., Wu, C., and Hu, X. (2011) Tetrahedron: Asymmetry, 22, 840.
15 (a) Guillena, G., Hita, M. del C., and Nájera, C. (2006) Tetrahedron: Asymmetry, 17, 729; (b) Guillena, G., Hita, M. del C., and Nájera, C. (2006) Tetrahedron: Asymmetry, 17, 1027; (c) Guillena, G., Hita, M. del C., and Nájera, C. (2006) Tetrahedron: Asymmetry, 17, 1493; (d) Guillena, G., Hita, M. del C., Nájera, C., and Viózquez, S.F. (2008) J. Org. Chem., 73, 5933.
16 (a) Guizzetti, S., Benaglia, M., Pignataro, L., and Puglisi, A. (2006) Tetrahedron: Asymmetry, 17, 2754; (b) Guizzetti, S., Benaglia, M., Raimondi, L., and Celentano, G. (2007) Org. Lett., 9, 1247.
17 Gryko, D., Kowalczyk, B., and Zawadzki, L. (2006) Synlett, 1059.
18 Ma, G.-N., Zhang, Y., and Shi, M. (2007) Synthesis, 197.
19 Jiang, M., Zhu, S.-F., Yang, Y., Gong, L.-Z., Zhou, X.-G., and Zhou, Q.-L. (2006) Tetrahedron: Asymmetry, 17, 384.
20 Review: Gryko, D., Chrominski, M., and Pielacinska, D.J. (2011) Symmetry, 3, 265.
21 (a) Gryko, D. and Lipinski, R. (2005) Adv. Synth. Catal., 347, 1948; (b) Gryko, D. and Lipinski, R. (2006) Eur. J. Org. Chem., 3864; (c) Gryko, D., Zimnicka, M., and Lipinski, R. (2007) J. Org. Chem., 72, 964; (d) Gryko, D. and Saletra, W.J. (2007) Org. Biomol. Chem., 5, 2148.
22 (a) Almasi, D., Alonso, D.A., and Nájera, C. (2008) Adv. Synth. Catal., 350, 2467; (b) Almasi, D., Alonso, D.A., Balaguer, A.-N., and Nájera, C. (2009) Adv. Synth. Catal., 351, 1123.
23 Wang, B., Chen, G., Liu, L., Chang, W., and Li, J. (2009) Adv. Synth. Catal., 351, 2441.
24 (a) Tang, Z., Jiang, F., Yu, L.-T., Cui, X., Gong, L.-Z., Mi, A.-Q., Jiang, Y.-Z., and Wu, Y.-D. (2003) J. Am. Chem. Soc., 125, 5262; (b) Tang, Z., Jiang, F., Cui, X., Gong, L.-Z., Mi, A.-Q., Jiang, Y.-Z., and Wu, Y.-D. (2004) Proc. Natl. Acad. Sci. U.S.A., 101, 5755; (c) Guo, H.-M., Cun, L.-F., Gong, L.-Z., Mi, A.-Q., and Jiang, Y.-Z. (2005) Chem. Commun., 1450; (d) Tang, Z., Yang, Z.-H., Chen, X.-H., Cun, L.-F., Mi, A.-Q., Jiang, Y.-Z., and Gong, L.-Z. (2005) J. Am. Chem. Soc., 127, 9285; (e) Xu, X.-Y., Wang, Y.-Z., Cun, L.-F., and Gong, L.-Z. (2007) Tetrahedron: Asymmetry, 18, 237; (f) He, L., Jiang, J., Tang, Z., Cui, X., Mi, A.-Q., Jiang, Y.-Z., and Gong, L.-Z. (2007) Tetrahedron: Asymmetry
