Enantioselective hydrogenation of cyclic imines catalysed by Noyori-Ikariya half-sandwich complexes and their analogues.

A method for enantioselective hydrogenation of cyclic imines with gaseous hydrogen has been developed. Easily accessible Noyori-Ikariya Ru(II) and Rh(III) complexes can be used directly without an inert atmosphere. Substrate activation has been achieved by trifluoroacetic acid. A new hydroxyl-functionalized complex is reported, showing high activity in transfer hydrogenation.