ASYMMETRIC HYDROGENATIONS CATALYSED BY DIPHOSPHINITE RHODIUM COMPLEXES DERIVED FROM NATURAL TARTARIC ACID

Article abstract of DOI:10.1016/S0022-328X(00)89118-4

Two chiral diphosphinites, derived from natural tartaric acid, have been prepared and used as ligands for the preparation of two asymmetric hydrogenation catalysts, which were isolated in a crystalline state.After several weeks storage, these catalysts are still effective in the asymmetric hydrogenation of α-acetamido- and α-benzamido-cinnamic acid, citraconic acid, 2-phenyl-1-butene.In the hydrogenation of amino acid precursors the optical yields ranged from 14 to 44percent.Starting from a given substrate, each of the two enantiomers can be obtained by appropriate choice of one of our two catalysts, which are thus complementary to each other.The influence on the optical yield of various factors in the hydrogenations are considered.