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(OAc)(2) (3 mol %) and 1,3-bis(diphenylphosphino)propane (6 mol %) in THF at 110 degrees C gave 2-(phenylthiocarbonyl)-1,3-dienes in moderate to good yields. The thiocarbonylation takes place with high chemo- and regioselectivity, with the attack by the phenylthiocarbonyl group occurring exclusively at carbon-2 of the 1,3-conjugated enyne.