Highly Efficient and Enantioselective Iridium-Catalyzed Asymmetric Hydrogenation of N-Arylimines

A catalytic method employing the cationic iridium-(S-c,R-p)-DuanPhos [(1R,1'R,2S,2'S)-2,2'-di-tert-butyl-2,2',3,3'-tetrahydro-1H,1'H-1,1'-biisophosphindole] complex and BARF {tetrakis[3,5-bis(trifluoromethyl)phenyl]borate} counterion effectively catalyzes the enantioselective hydrogenation of acyclic N-arylimines with high turnover numbers (up to 10,000 TON) and excellent enantioselectivities (up to 98% ee), achieving the practical synthesis of chiral secondary amines.