Investigation of the mechanisms of palladium-catalyzed C-H acetoxylation and methoxylation by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the progress of the Pd-catalyzed acetoxylation and methoxylation of carbon-hydrogen bonds with PhI(OAc)(2) as an oxidant. The reaction intermediates were characterized by high-resolution ESI-MS. The reaction mechanisms are proposed to be Pd(II)-Pd(IV) or Pd(II)-Pd(III) redox cycles depending on the sigma-donor ligand and the solvent polarity.