Enantioselective cooperative catalysis within frustrated lewis pair complexes

Abstract

Cooperative actions of two or more Lewis acid and/or Lewis base catalysts can be exploited to promote enantioselective transformations that are not readily achieved by a single catalyst system. Nonetheless, undesirable acid–base complexation which occurs in a reaction mixture containing the catalysts, substrates, and products often results in poor reaction efficiency and a contrived substrate scope. In this article, we highlight our development of multi–catalyst systems that facilitate enantioselective transformations of otherwise unreactive C–H bonds contained in various carbonyl compounds and N–alkylamines while overcoming the formation of inert Lewis adducts. Such methods were achieved through the identification of catalyst/substrate combinations that form frustrated Lewis pairs (FLPs), namely, highly active acids and bases whose mutual quenching is precluded due to steric and electronic factors.