Light-induced aryldifluoromethyl-sulfonylation/thioetherification of alkenes using arenethiolates as a photoreductant and sulfur source

Abstract

Herein, we report a practical and mild synthetic protocol for a three-component reaction among alkenes, trifluoromethyl aromatics, and arylthiols. In this reaction, the selective C–F activation of trifluoromethyl aromatics occurs. The arenethiolate in the system plays dual roles: an electron donor and a radical trapping reagent. This process only releases a fluoride anion as a by-product within 2 hours. Moreover, the obtained difluoromethyl thioether could be further oxidized with meta-chloroperoxybenzoic acid (m-CPBA) to obtain unique yet challenging and almost unprecedented sulfonyl-based gem-difluoromethyl products with more than 36 substrates and up to 95% yield. Our protocol could easily scale up to yield 3.4 grams of product, which is the core structure required for further functionalization. These transformations can be applied to late-stage molecular development, which could be of great interest and potential in bio-relevant and pharmaceutical fields. Essentially, both experimental studies and DFT calculations were conducted and the results suggested a pathway of photo-induced EDA (electron donor–acceptor) complex, followed by a radical–radical cross-coupling process.