Rhodium catalysed enantioselective hydrogenation in water using pyrphos bound to poly-acrylic acid as ligand

Coupling of pyrphos ((R,R)-3,4-bis-diphenylphosphino-pyrrolidine to poly-ac rylic acid (PAA) furnish a new water-soluble ligand (PAA-pyrphos), which ca n be successfully applied as a ligand in biphasic (H2O/EtOAc) rhodium catal ysed enantioselective hydrogenation of acetamido cinnamic acid. Contrary to the PAA-PPM (PPM=(2S,4S)-4-diphenylphosphino-2-diphenylphosphino-methylpyr rolidine) ligand system the enantioselectivity of catalysts based on the PA A-pyrphos ligand system is virtually unaffected by changes in reaction para meters which influence the local phosphine concentration. (C) 2000 Elsevier Science B.V. All rights reserved.