Gaseous SF(3)(+): An efficient electrophilic monofluorinating agent for five-membered heteroaromatic compounds

Reactions of gaseous SF(3)(+) ions with furan, thiophene, pyrrole, and several of their alkyl derivatives were performed via MS(2) experiments and found to occur readily both by electron abstraction and F(+) transfer. Then, by performing MS(3) experiments, the F(+) transfer products-the protonated monofluorinated molecules-were mass-selected and deprotonated by a second reaction with a stronger base. F(+) transfer from gaseous SF(3)(+) followed by deprotonation promotes therefore C-H by C-F replacement in five-membered heteroaromatic compounds and the efficient gas-phase synthesis of their neutral monofluorinated derivatives.