Regioselective hydroesterification of 1-alkynes catalyzed by palladium–phosphine complexes

Abstract

The reaction of 1-alkynes, CO, and methanol (hydroesterification) catalyzed by palladium–phosphine complexes has been studied in acetonitrile media. Branched α,β-unsaturated ester was mainly produced in the presence of a catalytic amount of a palladium complex containing PPh 3. In contrast, dppf-based palladium complexes showed excellent regioselectivity for the formation of linear α,β-unsaturated ester. On the other hand, hydroesterification of 1,7-octadiyne with a catalyst system of Pd(OAc) 2/PPh 3/TsOH followed a different path to give a cyclized carbonylation product as the major product. A tentative mechanism involving a PdH species has been proposed for these reactions.