Mechanistic Investigation of a Synthetic Route to Biaryls by the Sigmatropic Rearrangement of Arylsulfonium Species

A comprehensive mechanistic investigation was conducted on the coupling reaction of aryl sulfoxides with phenols by using trifluoroacetic anhydride to yield biaryls. NMR experiments revealed that our previously proposed mechanism, which consists a cascade an interrupted Pummerer and rate-determining [3,3] sigmatropic rearrangement, is reasonable. The electronic effects substrates were also evaluated elucidate nature rearrangement step. Based experimental observations theoretical calculations, we conclude highly asynchronous stepwise rather than concerted when electron-rich are employed for reaction.