Enantioselective Synthesis Based on Catalysis by Chiral Oxazaborolidinium Cations

摘要

During the 1980s, proline-derived chiral oxazaborolidines of general structure 1 (Figure 1) were introduced as catalysts for enantioselective reduction of prochiral ketones. This process, sometimes referred to as the CBS (Corey-Bakshi-Shibata) reduction, has subsequently been applied to a wide range of ketonic substrates. A useful feature of the CBS reduction methodology is the availability of a well-defined stereochemical model for reduction (2 in Figure 1). The application of this methodology for the asymmetric synthesis of a wealth of natural products and non-natural molecules has been reviewed previously.