Asymmetric Catalysis from a Chinese Perspective

Table of Contents

1. Frontmatter

2. Chiral Spiro Catalysts

   Qi-Lin Zhou, Jian-Hua Xie

   Abstract

   Despite a number of highly efficient chiral ligands and catalysts have been developed in the past years, the searching for novel and efficient chiral ligands and catalysts is still required to satisfy the new needs of mankind for chiral compounds. This chapter describes the design and synthesis of chiral spiro ligands based on 1,1′-spirobiindane backbone and their applications in catalytic asymmetric transformations. The chiral catalysts containing these spirobiindane ligands exhibited excellent activities and enantioselectivities in a wide range of asymmetric reactions such as hydrogenations of enamines, α,β-unsaturated carboxylic acids, imines, ketones, and aldehydes, addition of organometallic reagents to α,β-unsaturated ketones, aldehydes, and imines, hydrovinylation of styrenes, reductive or alkylative coupling of dienes/alkynes and aldehydes, hydrosilylation/cyclization of 1,6-enynes, as well as X–H bond (X  =  O, N) insertion reactions, providing efficient and environment-benign approaches to various chiral compounds such as chiral amines and alcohols.

   Graphical Abstract

   Outline of Applications of Chiral Spiro Ligands

   Full size image

3. Chiral Phosphorus Ligands with Interesting Properties and Practical Applications

   Fuk Loi Lam, Fuk Yee Kwong, Albert S. C. Chan

   Abstract

   Asymmetric transformations using a catalytic approach remain significantly important in organic synthesis, especially in the preparation of pharmaceutically interesting molecules. Indeed, chiral phosphorus ligands play an important role in this area. In this chapter, the recent development and advancement of chiral phosphines, phosphites, phosphoramides, etc. are reviewed. The potentially practical organic transformations are also described.

4. Advances in Biocatalysis: Enzymatic Reactions and Their Applications

   Jiang Pan, Hui-Lei Yu, Jian-He Xu, Guo-Qiang Lin

   Abstract

   Biocatalysis is widely studied as an alternative to conventional chemical methods in chiral synthesis due to its high selectivity and the reaction ability under mild conditions. Various types of enzymes with high stereoselectivity have been screened from nature for the purpose of preparing important chiral synthons. In this chapter, some enzymatic reactions, including enantioselective bioresolution and asymmetric biotransformation, catalyzed by hydrolases, oxidoreductases and lyases, as well as their applications to chiral synthesis are overviewed, and some special enzymatic reaction modes, such as enantioconvergent reaction, dynamic kinetic resolution, and deracemization, are described.

5. Enantioselective Biotransformations of Nitriles

   Mei-Xiang Wang

   Abstract

   Enantioselective biotransformations of nitriles using nitrile hydrolyzing microbial whole cell catalysts are a powerful method for the synthesis of highly enantioenriched carboxylic acids and amide derivatives. In this article, progress of Rhodococcus erythropolis AJ270-catalyzed enantioselective biotransformations of nitriles including various functionalized nitriles, α- and β-amino nitriles and β-hydroxy nitriles, cyclopropane-, oxirane-, aziridine- and azetidine-containing carbonitriles is summarized. Applications of enantioselective biotransformations of these nitriles in the synthesis of natural and bioactive products are also discussed.

   Graphical Abstract

   Full size image

6. Asymmetric Epoxidation Catalyzed by Chiral Ketones

   Man Kin Wong, Yiu Chung Yip, Dan Yang

   Abstract

   Chiral ketones have been developed as efficient catalysts for asymmetric alkene epoxidation in the past decades. The development of different classes of chiral ketones for asymmetric epoxidation of unfunctionalized alkenes will be discussed. In addition, studies on diastereoselective epoxidation are also covered.

7. Asymmetric Organocatalysis

   W. J. Liu, N. Li, L. Z. Gong

   Abstract

   Asymmetric organocatalysis has been receiving considerable attention in the last decade and thereby made tremendous advances. Chinese researchers have also intensified efforts to investigate asymmetric organocatalysis by using diverse types of disciplines, including enamine, iminium, Brønsted acid, carbene, and Lewis base catalysis. As a result, a large number of excellent catalysts and elegant protocols have come out from China. This article summarizes the most representative achievements in enantioselective organocatalysis from Chinese groups.

8. Enantioselective Catalysis with Structurally Tunable Immobilized Catalysts

   Qing-Hua Fan, Kuiling Ding

   Abstract

   Immobilization of a chiral homogeneous catalyst can in principle ­facilitate its separation and recycling, and therefore is of considerable interest to both academia and industry. A number of methods have been developed for the immobilization of chiral catalysts, typically including using inert organic or inorganic materials as supports. However, most of the classical immobilized catalysts suffered from inferior catalytic properties to their homogeneous counterparts due to the poor accessibility, random anchoring, or disturbed geometry of the active sites in the solid matrix. In this chapter, we present the progress made in the immobilization of chiral catalysts by focusing on core-functionalized dendrimers in asymmetric catalysis, asymmetric catalysis in nanopores of mesoporous materials, and self-supported chiral catalysts for asymmetric reactions. All the three types of immobilized catalysts possess relatively well-defined structures together with a tunable chiral environment around the catalytically active centers. Representative examples selected from the researches mostly reported by Chinese chemists have demonstrated the high efficiencies and enantioselectivities of these immobilized catalysts. The impacts of supports, such as isolation or confinement effect, on the catalysis will be discussed with emphasis on their application in enantioselective synthesis.

9. Transition Metal-Catalyzed Asymmetric Allylation

   Chang-Hua Ding, Xue-Long Hou

   Abstract

   Transition metal-catalyzed asymmetric allylation is a powerful tool for the asymmetric formation of C–C and C–X bond. This review provides a comprehensive overview of contribution made by Chinese organic chemists in these fields.

10. Enantioselective Reactions with Trisoxazolines

    Jian Zhou, Yong Tang

    Abstract

    A series of homochiral and heterochiral trisoxazolines were synthesized by a direct or modular approach. These trisoxazoline-derived metal complexes function as enantioselective Lewis acid catalysts for Friedel–Crafts, Kinugasa, 1,3-dipolar cycloaddition, cyclopropanation, and Diels–Alder reaction. In these catalyzed processes, trisoxazoline-derived chiral metal complexes exhibit excellent reactivity, good to excellent selectivity, and high tolerance towards moisture. In some cases, the reaction selectivity could be easily tuned by changing reaction parameters such as temperature and solvent. In these reactions, trisoxazoline-derived chiral catalysts achieved better enantiofacial control, higher catalytic activity, and higher tolerance of impurities than the corresponding bisoxazoline derived ones. In light of these features, it is assumed that the coordination of the oxazoline sidearm to the metal center improves the stability, activity, and chiral environment of the catalyst.

11. Adventure in Asymmetric Hydrogenation: Synthesis of Chiral Phosphorus Ligands and Asymmetric Hydrogenation of Heteroaromatics

    Xiang-Ping Hu, Duo-Sheng Wang, Chang-Bin Yu, Yong-Gui Zhou, Zhuo Zheng

    Abstract

    Catalytic asymmetric hydrogenations of prochiral unsaturated compounds, such as olefins, ketones, and imines, have been intensively studied and are considered as a versatile method of the synthesis of chiral compounds due to atom economy and operational simplicity. Since 2002, we mainly focused on synthesis of new phosphorus ligands, asymmetric hydrogenation of heteroaromatic compounds and palladium-catalyzed asymmetric hydrogenation. Significant contribution was made in the Dalian Institute of Chemical Physics. In this chapter, we hope to share our experience and adventure in the development of chiral monophosphite ligands and phosphine–phosphoramidite ligands, asymmetric hydrogenation of heteroaromatic compounds, and the development of new homogeneous palladium catalytic hydrogenation system, which have a wide range of applications in synthesis of chiral compounds.

12. Erratum to: Asymmetric Organocatalysis

    W. J. Liu, N. Li, L. Z. Gong

13. Backmatter