Ir/XuPhos-catalyzed direct asymmetric reductive amination of ketones with secondary amines

Abstract

A diverse array of bidentate P-containing ligands has been developed for Ir-catalyzed asymmetric hydrogenation, but chiral monodentate phosphine ligands have remained comparatively underexplored. We herein report a novel iridium catalyst with XuPhos as a chiral monodentate phosphine ligand for the direct asymmetric reductive amination of ketones with secondary amines. This catalytic system tolerates a wide range of substrates, providing a series of chiral tertiary amines efficiently with high enantioselectivities. The high catalytic activity is attributed to the presence of the aliphatic cyclohexyl group on the P-atom and the relative configuration of the ligand, which is crucial for XuPhos to act as a monodentate P-ligand for iridium.