Dramatic Rate Enhancement of Asymmetric Phase-Transfer-Catalyzed Alkylations

摘要

The synthesis of optically active organic molecules from prochiral substrates by using chiral catalysts under phase-transfer conditions is one of the most exciting topics in practical organic synthesis because of its operational simplicity, mild reaction conditions, and environmental consciousness.[1] Hence, numerous efforts have been devoted to the elaboration of effective chiral quaternary ammonium salts, and considerable progress has recently made it possible to successfully perform various asymmetric bond-forming reactions under mild phase-transfer conditions.[2] However, one intrinsic yet critical problem associated with this type of reaction is insufficient catalytic efficiency, which often necessitates the use of a relatively large amount of catalyst (1-10 mol %).