Enantioselective reduction of acetophenone with PMHS and tin(II) complexes of chiral pyridine ligands

A number of tin(II) complexes, prepared in situ from tin(II) triflate and pyridine derivatives (2,2′:6′,2″-terpyridine, 1,10-phenanthroline, 2,2′-bipyridine, dipyridylmethane, 2-(thiophen-2-yl)pyridine and 2-(2-diphenylphosphinophenyl)-5,6,7,8-tetrahydroquinoline), have been used as chiral catalysts for the reduction of acetophenone in the presence of polymethylhydrosiloxane (PMHS). Yields up to 82% and enantioselectivities up to 19% have been obtained.