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 'spectator' 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.