Asymmetric sulfoxidation of prochiral sulfides using aminoalcohol derived chiral C3-symmetric trinuclear vanadium Schiff base complexes

A series of trimeric variants of the efficient and well known Bolm's chiral vanadium salen catalysts are reported. These C3-symmetric trinuclear chiral Schiff bases were synthesized by condensing a variety of trialdehydes with optically active aminoalcohols. The catalytic activity of the chiral vanadium complexes of these ligands was investigated for the enantioselective oxidation of prochiral sulfides using hydrogen peroxide as an oxidant. The procedure afforded the corresponding sulfoxide in good yield and the enantioselectivities were comparable to those obtained with the mononuclear complexes.