Coupling of pyrphos ((R,R)-3,4-bis-diphenylphosphino-pyrrolidine to poly-acrylic acid (PAA) furnish a new water-soluble ligand (PAA-pyrphos), which can be successfully applied as a ligand in biphasic (H2O/EtOAc) rhodium catalysed enantioselective hydrogenation of acetamido cinnamic acid. Contrary to the PAA-PPM (PPM=(2S,4S)-4-diphenylphosphino-2-diphenylphosphino-methylpyrrolidine) ligand system the enantioselectivity of catalysts based on the PAA-pyrphos ligand system is virtually unaffected by changes in reaction parameters which influence the local phosphine concentration.