Electrolytic partial fluorination of organic compounds. Part 51. Electrochemical fluorination of 1-methylpyrroles having electron-withdrawing groups at the 2-position: Effect of supporting fluoride salts on the fluorinated product selectivity

Anodic fluorination of 1-methylpyrroles having electron-withdrawing groups at the 2-position was comparatively studied using Et₃N • 3HF and Et₃N • 2HF as a supporting electrolyte and a fluorine source. The use of Et₃N • 3HF gave trifluorinated products predominantly or selectively depending on solvents used while the use of Et₃N • 2HF provided the corresponding monofluorinated pyrrole derivatives in considerable amount along with the trifluorinated products regardless of the solvents. This is the first successful example of selective anodic fluorination of pyrroles. The effects of supporting electrolyte on product selectivity are discussed.