Oxidative Fluorination of N‐Arylsulfonamides.

We report a late stage oxidative nucleophilic fluorination of N-arylsulfonamides, a class of compounds so far not considered as precursors to 4-fluorophenyl sulfonamides. By installing a para-positioned tert-butyl substituent on the aniline, oxidative fluorination takes place regioselectively in the presence of HF·pyridine and PIDA. This methodology has been shown to give good yields for a variety of ortho- and meta-functionalised N-arylsulfonamides and has been adapted for radiofluorination to give 4-[18F]fluorophenyl sulfonamides under carrier added conditions.