Chiral Dienes as “Ligands” for Borane-Catalyzed Metal-Free Asymmetric Hydrogenation of Imines

This paper describes a highly enantioselective metal-free hydrogenation of imines using chiral dienes as "ligands" for the generation of catalysts with HB(C6F5)2 by hydroboration in situ to furnish a variety of chiral amines with up to 89% ee, which provides a practical strategy for the development of novel chiral frustrated Lewis pairs for asymmetric hydrogenation.