Trifluoromethanesulfinyl Chloride for Electrophilic Trifluoromethythiolation and Bifunctional Chlorotrifluoromethythiolation

Trifluoromethanesulfinyl chloride (CF₃SOCl) has been introduced as a new reagent for C−H trifluoromethylthiolation of indoles, thiophenes, and ketones under catalyst-free conditions and in the absence of reductant. The disproportionation of CF₃SOCl to CF₃SO₂Cl and CF₃SCl provides two pathways for the trifluoromethylthiolation. Direct trifluoromethylthiolation with CF₃SCl or trifluoromethylsulfoxidation with CF₃SOCl is followed by reduction with CF₃SOCl. This reagent can be used to functionalize benzothiophenes, benzofurans, and indenes under the promotion of Ag₂CO₃. It can also be used for trifluoromethylthiolation of thiols and benzeneselenols, and 1,2-bifunctional chlorotrifluoromethylthiolation of indoles, styrenes, and alkyenes. The method can also be extended for difluorometylthiolation reactions using CF₂HSOCl.