Transition metal catalyzed reaction of 1-buten-3-yne with acetic acid

The reaction of 1-buten-3-yne with acetic acid was examined in the presence of transition metal catalysts. Among catalysts examined, Pd(OAc)(2) or H-2 [PtCl6] was an effective catalyst forconverting 1-buten-3-yne to the corre sponding acetic acid adducts and corresponding dimerization product. With t hese catalysts a mixture of 1-acetoxy-1,3-butadiene and 2-acetoxy-1,3-butad iene was obtained along with the dimerization product (1,3,7-octatriene-5-y ne). Under Pd (OAc)(2) catalyst, the dimerization product was produced almo st exclusively. The mechanism for the formation of this head-to-head dimeri zation product is discussed.