Binuclear and polynuclear rhodium complexes containing chiral dithiolate ligands derived from lactic acid

Two precursors of the chiral dithiolato ligands, di-[(2R)-acetylmercaptopro pyl] phthalate and isophthalate, 1 and 2 respectively, were synthesized fro m (S)-lactic acid. Reactions of 1 and 2 with [Rh-2(mu)-OMe)(2)(cod)(2)] (co d = 1,5-cyclo-octtadiene) yielded rhodium thiolato complexes of different n uclearities. The mixtures of complexes were analyzed by gel-permeation chro matography (GPC). The reaction with ligand 1 produced a mixture of oligomer ic complexes, where the binuclear species was the main component. Higher-nu clearity complexes were the main products of the reaction with ligand 2, Th e rhodium complexes, in the presence of PPh3, were tested as catalyst precu rsors for the asymmetric hydroformylation of styrene, Moderate activity and regioselectivity were achieved in most cases, but no enantioselective disc rimination was observed, Copyright (C) 2000 John Wiley & Sons, Ltd.