Electrochemical partial fluorination of α,β-unsaturated ketones

Anodic fluorination of phenyl stryryl ketone and t-butyl styryl ketone using ammonium fluorides as fluorine source and supporting electrolyte in CH2Cl2 as electrolytic solvent, yields expected vicinal difluoroketones, as mixture of erythro and threo isomers. The anodic fluorination of phenyl 3,5-di-t-butyl-4-hydroxystyryl ketone yields only two monofluoro, compounds. A possible reaction mechanism is discussed.