Highly enantioselective hydrogenation of alpha-dehydroamino acids by rhodium complexes with new unsymmetric P-chirogenic bisphosphine ligands.
[figure: see text] New rhodium catalysts with unsymmetric P-chirogenic bis(phosphino)ethanes, BisP*-Rh, exhibited very high enantioselectivity (98-99%) in the hydrogenation of alpha-dehydroamino acid derivatives. Such high enantioselectivity should result from the asymmetric environment around the Rh atom, as was shown in the molecular structure of the catalyst analyzed by X-rays. The asymmetry can be controlled by the combination of the alkyl groups on the two phosphorus atoms.
Ohashi
A
A
Department of Chemistry, Faculty of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Imamoto
T
T