Imidazolium ion tethered TsDPENs as efficient ligands for Iridium catalyzed asymmetric transfer hydrogenation of α-keto phosphonates in water

Abstract

For the first time, an efficient method has been developed by the use of imidazolium ion tethered TsDPENs as efficient ligands for Iridium-catalyzed asymmetric transfer hydrogenation (ATH) of α-ketophosphonates in water. The reaction provided the desired product α-hydroxyphosphonates in moderate to good yields (44–78%) and good to excellent enantioselectivities (up to >99% ee) under mild reaction conditions without adding any surfactants. The enantiomeric excess was determined by 13P NMR by using (−)-cinchonidine as chiral solvating agent, which is a much more convenient method than chiral HPLC.