High-branched selectivity in the palladium-catalysed alkoxycarbonylation of styrene in the presence of thiol-thioether atropisomeric ligands

New mononuclear and dinuclear palladium complexes containing one neutral an d one anionic sulfur donor centre derived from the atropisomeric thiol-thio ether derivative 3 (RHbinas) were prepared and characterized both in soluti on 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 pre sence of triphenylphosphine and oxalic acid, the new complexes are active c atalysts for the hydrocarboxylation of styrene, showing a high regioselecti vity towards the branched product under mild conditions (up to 97% of 2-phe nylpropanoic acid). (C) 1999 Elsevier Science B.V. All rights reserved.