Asymmetric hydrogenation of imines catalyzed by iridium complexes with phosphine–phosphite ligands: importance of backbone flexibility

Chiral phosphine–phosphites provide an alternative class of ligands for the iridium catalyzed enantioselective hydrogenation of imines. Optimization of ligand structure has afforded enantioselectivities up to 84% ee in the reduction of N-aryl imines. A significant influence of backbone nature on enantioselectivity has also been observed.