Chiral Metal Nanoparticles for Asymmetric Catalysis
Metal nanoparticles modified by chiral ligands or chiral polymers, called as “chiral metal nanoparticles,” are promising catalysts for asymmetric organic transformations. In this chapter, the class of chiral modifiers is focused to overview advance in the
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Chiral Metal Nanoparticles for Asymmetric Catalysis Tomohiro Yasukawa and Shū Kobayashi
Contents 1 Introduction 2 Chiral Amine-Modified Nanoparticle Catalysts 2.1 Cinchona Alkaloids and Their Derivatives Modified Nanoparticle Catalysts 2.2 Chiral Diamine-Modified Nanoparticle Catalysts 2.3 Amino Acid-Modified Nanoparticle Catalysts 3 Chiral Phosphine-Modified Nanoparticle Catalysts 3.1 Asymmetric Hydrogenation 3.2 Asymmetric Hydrosilylation 3.3 Asymmetric C–C Bond-Forming Reaction 3.4 Miscellaneous 4 Chiral N-Heterocyclic Carbene-Modified Nanoparticle Catalysts 5 Chiral Diene-Modified Nanoparticle Catalysts 6 Other Chiral Molecules as Modifiers 7 Chiral Polymer-Stabilized Nanoparticle Catalysts 8 Conclusion References
Abstract Metal nanoparticles modified by chiral ligands or chiral polymers, called as “chiral metal nanoparticles,” are promising catalysts for asymmetric organic transformations. In this chapter, the class of chiral modifiers is focused to overview advance in the field of metal nanoparticle-catalyzed asymmetric reactions.
T. Yasukawa Green and Sustainable Chemistry Social Cooperation Laboratory, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan S. Kobayashi (*) Green and Sustainable Chemistry Social Cooperation Laboratory, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan Department of Chemistry, School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan e-mail: [email protected]
T. Yasukawa and S. Kobayashi
Keywords Asymmetric catalysis · Chiral metal nanoparticles · Chiral modifier · Heterogeneous catalysts
1 Introduction Development of enantioselective catalysis is an important subject as it is an effective process to synthesize target chiral molecules that are further led to useful compounds such as medicines and pesticides [1, 2]. Research using small chiral molecules including metal complexes and organocatalysts as catalysts is a current mainstream in the field of asymmetric catalysis. Numerous homogeneous small molecule catalysts were developed to date, and various transformations were achieved with excellent enantioselectivity. On the other hand, use of chiral molecule-modified surface of metal nanoparticles or supported metal species for asymmetric catalysis was overwhelmingly less developed, though this strategy is attractive because supported metal species are easily separated from a reaction mixture and reused. Indeed, this concept was realized in the early stage of investigations for asymmetric catalysis. In 1956, Akabori et al. reported a Pd catalyst immobilized on silk fibroin fiber for asymmetric hydrogenation of imines as a first example of surface asymmetric catalysis (Scheme 1) [3]. In this reaction, enantioselectivity was still low, and the structure of a chiral modifier was not well-defined. Several years later, the same group reported small chiral molecules such as amino acid- or tartaric acid-modified Raney Ni-catalyzed asymmetric hydrogenations of carbonyl compounds achieving high enantioselectivity (Scheme 1)
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