Enantioselective Cooperative Catalysis within Frustrated Lewis Pair Complexes

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.