Synthesis of novel chiral binaphthyl phosphorus ligands and their applications in Rh-catalyzed asymmetric hydrogenation

A series of new chiral mono- or bidentate phosphorus ligands were efficiently prepared through a key intermediate (S)-4-chloro-4,5-dihydro-3H-4-phosphacyclohepta[2,1-a;3,4-a′]binaphthalene and its derivatives. These ligands were applied in the Rh-catalyzed asymmetric hydrogenation of α-dehydro amino acids, enol acetates, itaconates, and enamides. Good to excellent enantioselectivities were obtained (up to 99.5% ee).