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 σ-donor ligand and the solvent polarity.