Synthesis of a water-soluble cationic chiral diamine ligand bearing a diguanidinium and application in asymmetric transfer hydrogenation

Abstract

A novel water-soluble cationic N-monosulfonated chiral diamine ligand diguanidinium 1c was easily prepared from ( R, R)-DPEN and its rhodium complex and was successfully applied in the asymmetric transfer hydrogenation of prochiral ketones and imines in water by using sodium formate and formic acid as co-hydrogen donors. Various substrates were reduced with high yields and good to excellent enantioselectivities (up to >99% ee).