Asymmetric Transfer Hydrogenation of Aromatic Ketones Catalyzed by New Chiral Diaminodiphosphine-Iridium(I) Systems

The chiral PNNP ligands containing-CH3 substituents have been synthesized and characterized by NMR,MS,IR and CD spectra.The chiral diaminodiphosphine-iridium(I) systems,prepared in situ from [IrHCl2(COD)]2 and the ligands 1 and 2,have been explored.The catalytic performance was investigaed in the asymmetric transfer hydrogenation of various aromatic ketones in iPrOH.The results indicated that the catalytic system acted as an excellent catalyst precursor in asymmetric transfer hydrogenation of various aromatic ketone.When the(R,R)-2/[IrHCl2(COD)]2 as catalyst was employed for the reduction of the 1,1-diphenylacetone at room tempreture,high activity(99% conversion) and excellent enantioselectivity(99% ee) were obtained.