Synthesis of beta-dimethylsulfonium- and beta-methylthio-substituted vinyl triflates by reaction of acetylenes with dimethyl sulfide ditriflate

A one-pot synthesis of beta-dimethylsulfonium-substituted vinyl triflates by the reaction of dimethyl sulfide ditriflate with acetylenes is described. beta-Dimethylsulfonium-substitute vinyl triflates were found to exhibit unusual reactivity towards nucleophiles resulting in demethylation of sulfonium salts, but not substitution of triflate. Demethylation of these sulfonium salts with diethylamine gave the corresponding beta-methylthio-substituted vinyl triflates. The possibility of thiophene derivative synthesis via triflic anhydride promoted cyclization of sulfoxide was studied.