Deaminative Fluorination of Sulfonamides via Aminocyclopropenium Activation

This report discloses a deaminative fluorination of secondary sulfonamides promoted by diaminocyclopropenium activation. The reaction proceeds through isolable sulfonamide-cyclopropenium adducts that undergo selective substitution at sulfur upon treatment with fluoride. This method provides access to sulfonyl fluorides from abundant sulfonamides, enabling the functionalization of bioactive molecules as well as the mild cleavage of sulfonamide protecting groups.