High-branched selectivity in the palladium-catalysed alkoxycarbonylation of styrene in the presence of thiol–thioether atropisomeric ligands
摘要:
New mononuclear and dinuclear palladium complexes containing one neutral and one anionic sulfur donor centre derived from the atropisomeric thiol-thioether derivative 3 (RHbinas) were prepared and characterized both in solution and in the solid state. Crystal structures of [PdCl(Mebinas)](2) (4) and [PdCl(Mebinas)(PPh3)] (6) were determined by X-ray diffraction. In the presence of triphenylphosphine and oxalic acid, the new complexes are active catalysts for the hydrocarboxylation of styrene, showing a high regioselectivity towards the branched product under mild conditions (up to 97% of 2-phenylpropanoic acid). (C) 1999 Elsevier Science B.V. All rights reserved.