Enamine–Metal Lewis Acid Bifunctional Catalysis: Application to Direct Asymmetric Aldol Reaction of Ketones

Abstract Unprecedented bifunctional enamine–metal Lewis acid catalysts have been developed. In this bifunctional catalytic system, a tridentate ligand tethered with a chiral secondary amine was designed to solve the acid–base self‐quenching problem leading to catalyst inactivation. This new bifunctional enamine–metal Lewis acid catalyst was found to catalyze aldol reactions of ketones efficiently in high yields and good to excellent diastereoselectivities and enantioselectivities.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)