Synthesis of Monofluoromethylarenes: Direct Monofluoromethylation of Diaryliodonium Bromides using Fluorobis(phenylsulfonyl)methane (FBSM)

A metal-free protocol for the synthesis of monofluoromethylarenes using diaryliodonium salts and fluorobis(phenylsulfonyl)methane (FBSM) is disclosed. This work represents a facile alternative to traditional metal-mediated monofluoromethylation reactions and utilizes inexpensive and accessible starting materials. The target products can be regioselectively synthesized in excellent yields (up to 97%) and with good functional group tolerance. The thus prepared compounds can be further reduced to furnish monofluoromethylarenes. Our investigations revealed that the counter anion of the iodonium species significantly affects the reaction yield. The ionic nature of the reaction mechanism involving an S_NAr type process is elucidated using Hammett's linear free energy analysis, and further supported by control experiments.