Pd(II) - dppb and syngas catalyze regioselective hydroesterification of terminal alkynes under neutral conditions

Palladium(II) regioselectively catalyzes the hydroesterification of terminal alkynes under syngas forming alpha,beta -unsaturated esters 3 and 4 in excellent chemical yields under neutral conditions. The high selectivity for the linear ester 4 was obtained with a catalytic system that includes Pd(II), 1,4-bis(diphenylphosphino)butane (dppb) and CO/H-2 in CH2Cl2 as solvent. The control of the regioselectivity depends strongly upon the type of ligand, the solvent and the use of the syngas mixture. (C) 2001 Elsevier Science Ltd. All rights reserved.