Direct vs Indirect Route in the Activation of Aroylpalladium(II) Complexes by Electron Transfer

Amatore, C.; CarrŽ, E.; Jutand, A.; Tanaka, H.; Torii, S.; Chiarotto, I.; Carelli, I. Electrochim. Acta 1997, 42, 2143.

Based on mechanistic investigations, it is established that it is not possible to invert the reactivity of aroyl halides, ArCO-X, and make them react with electrophiles, in the presence of a palladium catalyst and a source of electron. Indeed the key intermediate ArCO-Pd-XL₂ (L = PPh₃) whose activation by electron transfer in the presence of an electrophile would produce the coupling product ArCO-E, is less easily reduced than the corresponding aroyl halide.