Highly chemo- and regioselective thiocarbonylation of conjugated enynes with thiols and carbon monoxide catalyzed by palladium complexes: An efficient and atom-economical access to 2-(phenylthiocarbonyl)-1,3-dienes

The reaction of 1, 3-conjugated enynes bearing a terminal triple bond with thiols and carbon monoxide in the presence of catalytic quantities of Pd(OA c)(2) (3 mol %) and 1,3-bis(diphenylphosphino)propane (6 mol %) in THF at 1 10 degrees C gave 2-(phenylthiocarbonyl)-1,3-dienes in moderate to good yie lds. The thiocarbonylation takes place with high chemo- and regioselectivit y, with the attack by the phenylthiocarbonyl group occurring exclusively at carbon-2 of the 1,3-conjugated enyne.