On the mechanism of hydroesterification of styrene using an in situ-formed cationic palladium complex

The mechanism of hydroesterification of styrene using in situ-formed Pd(OTs)2(PPh3)2 from Pd(OAc)2, PPh3 and TsOH in methanol has been investigated by isolation and characterisation of catalytically active intermediates. From reaction mixtures, Pd–hydridocarbonyl and Pd–acyl complexes were isolated and characterised, based on which a Pd hydride mechanism has been proposed. Formation of palladium hydride species has also been confirmed by 31P-NMR experiments.