The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives

We herein report that the regioselective anodic fluorination of S-alkyl benzothioate and its derivatives in various aprotic solvents using Et3N center dot nHF (n = 3-5) and Et4NF center dot nHF (n = 3-5) as supporting electrolyte and a fluorine source successfully provided the corresponding alpha-fluorinated products in moderate yields. Dichloromethane containing Et4NF center dot 4HF was found to be the most suitable combination as electrolytic solvent and supporting salt as well as fluorine source for the anodic fluorination. The electrochemical fluorination of cyclic benzothioates such as benzothiophenone was also achieved.