Catalytic asymmetric hydrogenation using ruthenium(II) complexes with chelating chiral sulfoxide ligands

Abstract

A chelating sulfoxide ligand, (2R,3R)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(methyl sulfinyl)butane monohydrate, or 'dios', containing chiral carbons has been synthesized. A corresponding bis(benzyl sulfinyl) compound, 'bdios', and an acetal-cleaved derivative, 'ddios', are also reported. Ruthenium(II) neutral complexes have been made containing such ligands, which can bind via oxygen or sulphur; the complexes are active homogeneous catalysts for hydrogenation of prochiral olefinic acid substrates; optical purities of up to 25% were attained.