Transition-metal-containing chiral bidentate ligands for enantioselective catalysis: non-metallocene architectural units come of age

Structural and electronic properties associated with donor ligands that contain ʹspectatorʹ transition-metal fragments are analyzed. The current status of such non-ferrocenyl chiral bidentate ligands is reviewed from the standpoint of synthesis, applications in metal-catalyzed enantioselective reactions, and future directions.