Synthesis of novel chiral tetraaza ligands and their application in enantioselective transfer hydrogenation of ketones

Novel chiral tetraaza ligands (R)-N, N′-bis[2-(piperidin-1-yl)benzylidene]propane-1, 2-diamine 6 and (S)-N-[2-(piperidin-1-yl)benzylidene]-3-{[2-(piperidin-1-yl)benzylidene]amino}-alanine sodium salt 7 have been synthesized and fully characterized by NMR, IR, MS and CD spectra. The catalytic property of the ligands was investigated in Ir-catalyzed enantioselective transfer hydrogenation of ketones. The corresponding optical active alcohols were obtained with high yields and moderate ees under mild reaction conditions.