Ir-Catalyzed Asymmetric Ketimine Hydrogenation

Significance

An Ir-catalyzed asymmetric hydrogenation of N-PMP ketimines using a chiral sulfoximinylphosphine as ligand gave good to excellent enantioselectivities and full conversion with 1 mol% catalyst loading within a few hours. A variety of aryl alkyl ketimines of different steric and electronic character were tolerated. More importantly, an E,Z-isomeric mixture of starting ketimines gave the products in excellent enantio­selectivities. Lower Ir catalyst loading (0.1 mol%) was also able to achieve full conversion under increased H₂ pressure without erosion of enantioselectivity. The N-PMP-protecting group can be easily removed under oxidative conditions (i.e. CAN).