At -78 °C, n-butyllithium (1.67 M hexane solution, 1.3 mL, 2.2 mmol) was slowly added dropwise to a tetrahydrofuran (3 mL) solution of p-bromoanisole (383 mg, 2.0 mmol) and the dropwise process lasted for 30 min. Subsequently, N,N-dimethylformamide (0.22 mL, 2.2 mmol) was added to the reaction mixture and the mixture was warmed up to room temperature with stirring. After 2 hours of reaction, the tetrahydrofuran was removed under reduced pressure. Methanol (3 mL) was added to the residue and stirring was continued for 30 minutes at room temperature. Subsequently, the reaction mixture was cooled to 0 °C, iodine (1523 mg, 6 mmol) and potassium carbonate (829 mg, 6 mmol) were added sequentially, and then the mixture was warmed to room temperature and stirred for 22 hours. After completion of the reaction, the reaction was quenched with saturated aqueous sodium sulfite (5 mL) and extracted with chloroform (3 x 20 mL). The organic layers were combined, washed with brine, dried over anhydrous sodium sulfate and concentrated to give methyl 4-methoxybenzoate in 82% yield. If necessary, the product can be purified by short column chromatography (silica gel: hexane/ethyl acetate = 9:1) to obtain pure methyl 4-methoxybenzoate as a colorless oil.
