Enantioselective Synthesis of Chiral Fluorinated Amines via Manganese-Catalyzed Asymmetric Hydrogenation

A highly enantioselective Mn-catalyzed hydrogenation of fluorinated imines has been realized. The success of this hydrogenation is attributed to the use of the chiral ferrocenyl P,N,N ligand bearing an additional chiral center at the pyridinylmethyl position. The hydrogenation displayed broad functional group tolerance, thus furnishing a wide range of optically active fluorinated amines with up to 98% enantiomeric excess. The utility of the methodology has been well-demonstrated by the scale-up of the asymmetric hydrogenation of N-(4'-methoxyphenyl)-ethan-2,2,2-trifluoro-1-phenyl-1-imine.