General procedure for the synthesis of methyl 3-cyano-4-methoxybenzoate from methyl 3-bromo-4-methoxybenzoate: to a solution of methyl 3-bromo-4-methoxybenzoate (1.1 g, 4.4 mmol) in dimethylformamide (10 mL) was added cuprous cyanide (1.2 g, 13.2 mmol). The reaction mixture was heated to 140 °C and maintained for 6 hours. After the reaction was completed, it was cooled to room temperature and diluted by adding ethyl acetate (25 mL). The organic phase was washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by fast column chromatography (eluent: petroleum ether/ethyl acetate=10:1) to afford methyl 3-cyano-4-methoxybenzoate (662 mg, 79% yield) as a white solid.
