Scope of phenols^a.

^aStandard reaction conditions: graphite rod anode, graphite rod cathode, constant current = 10 mA. 2a (0.3–0.4 mmol), 1 (1.5 equiv.), n-Bu₄NBF₄ (1.0 equiv.), HFIP/CH₂Cl₂ (6 : 4, 10 mL), rt, 2 h, under N₂.