Synthesis of chiral amino acid derivatives in supercritical carbon dioxide using Rh-PipPhos catalyst

PipPhos ligand was used in the asymmetric Rh-catalysed hydrogenation of N-acyldehydroamino acid esters in supercritical carbon dioxide with enantioselectivities attained up to 97%. The catalytic performance is affected greatly by temperature and both hydrogen and total pressures.