Carbonylation of aromatic aldehydes to phenylacetic acid derivatives catalyzed by a palladium-triphenylphosphinehydrogenchloride system

Arom. aldehydes, e.g., vanillin, having electron-releasing para substituents, such as a hydroxy group, are carbonylated to phenylacetic acid derivs. in the presence of a Pd-PPh3-HCl catalytic system, at 90-120°, 50-100 atm of carbon monoxide, 1-2 h, in the presence of water or an alkanol. PPh3 and HCl play key roles in the catalysis, since in their absence no activity is obsd