Palladium-catalyzed oxyarylation of olefins using silver carbonate as the base. Probing the mechanism by electrospray ionization mass spectrometry

The Pd(OAc)2-catalyzed oxyarylation of electron-rich (8 and 12) and electron-poor (10) olefins by ortho-iodophenols (3a–d) was studied using Ag2CO3 as the base, in acetone, and in the presence and absence of PPh3. The corresponding adducts of oxyarylation were obtained in moderate yields. The reaction mechanism was examined by electrospray ionization mass spectrometry (ESI-MS). Cationic arylpalladium intermediate (14), formed by the oxidative insertion of Pd(0) into 3a, and the cationic palladacycles (15), obtained by reaction of 14 with olefins 8 and 12, were intercepted by ESI-MS and characterized by ESI-MS/MS.