Sulfonium salts are useful reagents for fluoroalkylation. For example, the trifluoromethylating agent (Umemoto's Reagent II) [D5335] affords trifluoromethylated products from various substrates.^1,2) The difluoromethylating agent [D5630] is suitable for metal-free photoredox-catalyzed difluorometylation.³⁾ In addition, these reagents are bench-stable and easily handleable solid reagents.

 The sulfonium-type trifluoromethylating agent (Umemoto's Reagent) [D5335] generates a trifluoromethyl radical (·CF3) without a photo-catalyst under light irradiation, and the resultant ·CF3 readily trifluoromethylates various aromatic compounds.²⁾

The Sulfonium-type difluoromethylating agent [D5630] also generates in-situ a difluoromethyl radical (·CHF₂) in the presence of a photo-cataylst (perylene) under blue LED irradiation. The radical species reacts with various alkenes to afford difluoromehylated products.³⁾