Anodic fluorination of phenols using Et3N-5HF electrolyte

In the presence of Et3N-5HF electrolyte, anodic fluorination of phenols (1) successfully afforded 4,4-difluorocyclohexa-2,5-diene-1-ones (11), which were readily converted to p-fluorophenols (9) in good yields by the subsequent reduction with Zn in acidic aqueous solutions. We have revealed some novel information on the oxidation mechanism of 1, which is well supported by the cyclic voltammogram of 1 in Et3N5HF.