Highly enantioselective hydrogenation of quinolines under solvent-free or highly concentrated conditions

Abstract

The phosphine-free chiral cationic Ru(OTf)(TsDPEN)(η6-cymene) complex was found to be an efficient catalyst for the enantioselective hydrogenation of quinolines under more environmentally friendly solvent-free or highly concentrated conditions. Excellent yields and enantioselectivities (up to 97% ee) were obtained at only 0.02–0.10 mol% catalyst loading.