Enantioselective hydrogenation over chiral cobalt complexes with (+)-(1S,2S,5R)-neomenthyldiphenylphosphine and (-)-(R,R)-2,2-dimethyl-4,5-bis(diphenylphosphinomethyl)-1,3-dioxolane

The optical yield in enantioselective hydrogenation of methyl alpha-acetamidocinnamate over mono- and diphosphine cobalt(IT) complexes CoX2L2 [where X = Cl or CF3SO3, L = (+)-(1S,2S,5R)-neomenthyldiphenylphosphine or L-2 = (-)-(R,R)-2,2-dimethyl-4,5-bis(diphenylphosphinomethyl)-1,3-dioxolane], which are generated in situ, in the presence of sodium tetrahydridoborate increases with rise in the phosphine-to-metal ratio and hydrogen pressure. The maximal optical yields of (+)-(S)-N-acetylphenylalanine methyl ester attain 40% (CoX2L2) and 42% (COX2L2).