THE REGIOSELECTIVE HYDROCARBOALKOXYLATION OF 4-METHYLSTYRENE CATALYZED BY PALLADIUM COMPLEXES

Abstract

Effects of promoters and reaction conditions have been studied on the regioselectivity of palladium complex-catalyzed hydrocarboalkoxylation of 4-methylstyrene. A catalyst system of PdCl2-CuCl2-PPh(3) dissolved in a nonpolar solvent provided a nearly regiospecific conversion to the branched acid ester at high rates at 100 degrees C and 41 bar of CO pressure. The dependence of regioselectivity on employed phosphines (monodentate vs. bidentate ligands) suggested that the key catalytic species might be a palladium hydride complex rather than a carboalkoxy complex.