Fe-Catalyzed Fluorosulfonylation of Alkenes via Sulfur Dioxide Insertion: Synthesis of Lactam-Functionalized Alkyl Sulfonyl Fluorides.

A novel Fe-catalyzed fluorosulfonylation of alkenes with NaSO and -fluorobenzenesulfonimide (NFSI) for assembling various lactam-functionalized alkyl sulfonyl fluorides is disclosed. In this reaction, NaSO acts as both an SO source and a reductant. Furthermore, the resulting products can be efficiently transformed into valuable chemicals, including sulfonyl esters and sulfonamides, via the sulfur(VI) fluoride exchange (SuFEx) click reaction. Preliminary mechanistic studies suggest that the transformation proceeds through intramolecular radical cyclization, SO insertion, sulfite anion formation, and fluorination.