Iridium-Catalyzed Asymmetric Hydrogenation of Dialkyl Imines

Asymmetric hydrogenation of dialkyl imines to chiral amines is difficult because the two alkyls of imines are so similar in spatial and electronic structure that chiral catalysts are difficult to distinguish between them. In this study, we described an asymmetric hydrogenation of dialkyl imines by a chiral iridium catalyst containing spiro phosphine-amine- phosphine ligand. By precisely adjusting the chiral pocket of catalyst, a highly efficient catalyst was developed. Using this catalyst, a variety of dialkyl imines were hydrogenated to chiral amines with high yield and enantioselectivity.