An Overview of 2,2,2‐Trifluoroethyl Sulfonium Salts: Preparation and Synthetic Applications

2,2,2‐trifluoroethyl sulfonium salts have emerged as the highly versatile trifluoroalkyl reagents in modern organic synthesis, due to their exceptional stability, ready availability, and ease of handling. 2,2,2‐Trifluoroethyl diphenylsulfonium salt has enabled many innovative trifluoroalkylation strategies, including photoredox trifluoroethylations, Fe‐catalyzed insertions, cyclopropanations, Johnson–Corey–Chaykovsky reactions, and 4 + 1 annulations, for the concise synthesis of a great deal of trifluoroethylated compounds and a variety of trifluoromethylated cyclopropanes, epoxides, aziridines, pyrrole derivatives, and pyrazolines, respectively, with high diastereoselectivity. This salt has also been used as an efficient cross‐coupling partner in the Pd‐ or Pd/Cu‐catalyzed Mizoroki–Heck, Suzuki–Miyaura, and Sonogashira arylation reactions. 2,2,2‐Trifluoroethyl sulfonium analogues, including pentafluoroethyl, α ‐diazo trifluoroethyl, and 1‐(trifluoromethyl)cyclopropyl sulfonium salts, have been developed to meet a wider range of synthetic requirements. These reagents can readily introduce pentafluoroethyl group, serve as an equivalent of trifluoromethyl carbyne cation, allow the simultaneous transfer of both trifluoromethyl and diazo groups, and enable the direct radical trifluoromethylcyclopropylation, highlighting their significant potentials for synthetic applications in pharmaceuticals, agrochemicals, and functional materials. This review provides a comprehensive summary of 2,2,2‐trifluoroethyl diphenylsulfonium salt and its analogues in organic synthesis, with emphasis on trifluoroalkylation and annulation.