General procedure for the synthesis of 2-ethoxy-4-bromobenzonitrile from 4-fluoro-2-hydroxybenzonitrile and iodoethane: 4-fluoro-2-hydroxybenzonitrile (50 mg, 0.32 mmol) was dissolved in N,N-dimethylformamide (DMF, 2 mL) in a round-bottomed flask and finely ground potassium carbonate (133 mg, 0.96 mmol) was added under stirring conditions. Subsequently, ethidium iodide (0.03 mL, 0.39 mmol) was slowly added dropwise to the reaction mixture. The reaction process was monitored by thin layer chromatography (TLC) until the feedstock completely disappeared. Upon completion of the reaction, the DMF solvent was removed by distillation under reduced pressure. The residue was dissolved in ethyl acetate and subsequently washed with saturated saline. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent ratio of petroleum ether: ethyl acetate = 5:1 to give 2-ethoxy-4-bromobenzonitrile (53.8 mg, 94% yield).
