Direct electrochemical synthesis of arenesulfonyl fluorides from nitroarenes: a dramatic ionic liquid effect

A practical electrochemical strategy for the direct synthesis of arenesulfonyl fluorides from industrial feedstock nitroarenes is described. The key to success lies in using a cheap ionic liquid N-methylimidazolium p-toluenesulfonate ([Mim]TolSO3) as an effective additive and electrolyte to facilitate the selective reduction of nitroarenes to the corresponding aniline intermediate, promoting the desired fluorosulfonylation with broad functional group tolerance under mild conditions. A practical electrosynthesis of aryl sulfonyl fluorides from nitroarenes is described. Cheap N-methylimidazolium p-toluenesulfonate has been found to be an effective additive, promoting the desired fluorosulfonylation under very mild conditions.