Trifluoromethyl Triflate: Synthesis and Reactions

Article abstract of DOI:10.1021/jo00228a001

A new and convenient synthesis of trifluoromethyl trifluoromethanesulfonate (trifluoromethyl triflate, TFMT) has been devised.The addition of triflic anhydride to a catalytic amount of antimony pentafluoride at 25 deg C produces TFMT in 94percent yield, utilizing a new and stronger Lewis acid catalyst produced in the reaction, F4SbOSO2CF3.This reaction makes pure TFMT conveniently and economically available in large quantities.A mechanism is presented that accounts for the substitution of a triflate ligand on antimony, as well as for the formation of TFMT.Trifluoromethyltriflate does not trifluoromethylate nucleophiles (pyridine, triethylamine, iodide, phenyllithium, phenylmagnesium bromide, lithium thiophenolate, or sodium naphthalenide) but gives products that result from an initial attack of the nucleophile at sulfur.Fluoride ion, which is formed by fragmentation of the trifluoromethoxide ion displaced from sulfur, is a chain carrier in the rapid decomposition of TFMT to give trifluoromethanesulfonyl fluoride and fluorophosgene.This limits the synthetic utility of trifluoromethyl triflate.