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. (C) 2005 Elsevier Ltd. All rights reserved.