trans -Trifluoromethyltetrafluorosulfanyl Chloride: Selective Synthesis and Reaction with Diazo Compounds.

trans -Trifluoromethyltetrafluorosulfanyl chloride ( trans -CF 3 SF 4 Cl) is a unique reagent for the incorporation of the CF 3 SF 4 group into organic compounds. However, CF 3 SF 4 Cl was prepared from hazardous reagents or formed as mixture of trans and cis isomers in low yield. Herein, a silver-promoted selective synthesis of trans -CF 3 SF 4 Cl under safe gas-reagent-free conditions is described. Furthermore, the synthetic application of trans -CF 3 SF 4 Cl is demonstrated through the new trifluoromethyltetrafluorosulfanylation of α-diazo carbonyl compounds.