Asymmetric hydrogenation: Chiral bis(phosphine)rhodium catalysts with phenyl group derivatives

Article abstract of DOI:10.1021/ic00136a002

Some attempts to achieve optically active products were carried out by new catalysts of the type [Rh(COD)(P*)₂]⁺, where the chiral phosphorus ligands are α-naphthylphenyl(o- or p-tolyl)phosphine (NPTP), bis[phenyl(o- or p-tolyl)phosphino]ethane (BPTE), bis(α-naphthylphenylphosphino)ethane (BNPE), and 1-phenyl-1,2-bis(diphenylphosphino)ethane (R-PDPE). Optical yields of 50-75% ee (ee = enantiomeric excess) were obtained in the hydrogenation of acetamidoacrylic acid. The ortho isomer of the tolyl group gave a higher optical yield than the para one. Isoalcohols were effective solvents. It was found that these catalysts can be recovered and reused for asymmetric hydrogenation.