Asymmetric Cyanation with the Chiral Ru-Li Combined Catalysts

Abstract

The combined systems of phenylglycinate/­BINAP/Ru(II) complex and Li compounds have been found to act as highly reactive and enantioselective catalysts for cyanosilylation and hydrocyanation of aldehydes, α-keto esters, α,β-unsaturated ketones, and N-protected aldimines. In this account, we describe the concept of catalyst design, the catalytic efficiency of the novel combined systems in the asymmetric cyanation, and the proposed reaction pathway based on the spectral analysis data. 1 Introduction 2 Cyanosilylation of Aldehydes and Ketones Catalyzed by LiCl 3 Asymmetric Cyanosilylation of Aldehydes and α-Keto ­Esters 3.1 Design of Chiral Ru–Li Combined Catalyst Systems 3.2 Cyanosilylation of Aldehydes 3.3 Cyanosilylation of α-Keto Esters 4 Asymmetric Hydrocyanation of Aldehydes, α,β-Unsaturated Ketones, and Aldimines 4.1 Hydrocyanation of Aldehydes 4.2 Conjugate Cyanation of α,β-Unsaturated Ketones 4.3 Strecker-Type Reaction 5 Mechanistic Considerations for Cyanosilylation of Aldehydes and Ketones 5.1 Achiral Reaction Catalyzed by LiCl 5.2 Asymmetric Reaction with the Chiral Ru–Li Combined Catalyst 6 Conclusion