Iron-Catalyzed Electrochemical α-C(sp3) Sulfonylation of Ethers and Pyrrolidine Derivatives with Sulfonyl Chlorides

Abstract

Selective α-C(sp3) sulfonylation of ethers and nitrogen heterocycles provides atom- and step-economical access to aliphatic sulfones, which are prevalent building blocks in pharmaceuticals and fine chemicals. Organic electrosynthesis and iron catalysis represent sustainable synthetic platforms for radical C–S bond formation, yet their combination for aliphatic α-C(sp3) sulfonylation remains underexplored. Herein, an undivided-cell iron-catalyzed electrochemical α-sulfonylation of ethers and N-protected pyrrolidines with sulfonyl chlorides is reported. The method benefits from traceless electrical redox equivalents, a cheap earth-abundant catalyst, and broad functional group compatibility. Gram-scale reactions and product derivatizations demonstrate its synthetic practicability. This electro-driven protocol leverages an anodic Fe(III)/Fe(II) redox shuttle to generate ethers and pyrrolidine derivatives as substrate-derived radical cation intermediates, with sulfonyl radicals originating from direct cathodic reduction of sulfonyl chlorides.