Example 7 Synthesis of methyl 2-bromo-4-methoxybenzoate (Compound 11): methyl 2-bromo-4-hydroxybenzoate (Compound 10, 815 mg, 3.54 mmol) was dissolved in N,N-dimethylformamide (DMF, 20 mL). Potassium carbonate (K2CO3, 1.17 g, 8.50 mmol) was added to the solution and the reaction mixture was stirred at room temperature for 20 minutes. Subsequently, the reaction mixture was cooled to 0 °C and a solution of iodomethane (265 μL, 4.25 mmol) in DMF (1 mL) was slowly added dropwise. After the dropwise addition, the reaction mixture was returned to room temperature and stirring was continued for 2 hours. Upon completion of the reaction, the reaction was quenched by the addition of water (50 mL) and then extracted with ether (Et2O, 200 mL). The organic phase was washed sequentially with water (3 x 40 mL) and saturated saline (40 mL). The organic layer was collected, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated. Finally, the target product methyl 2-bromo-4-methoxybenzoate (Compound 11, 849 mg, 95.9% yield) was purified by silica gel column chromatography (eluent: hexane solution of 15% ethyl acetate) as a brown liquid. The structure of the product was confirmed by 1H-NMR, 13C-NMR and mass spectrometry (ESI): 1H-NMR (CDCl3, 400 MHz) δ 7.87 (1H, d, J = 8.4 Hz, ArH), 7.19 (1H, s, ArH), 6.88 (1H, d, J = 8.4 Hz, ArH), 3.90 (3H, s, OCH3). 3.84 (3H, s, OCH3); 13C-NMR (CDCl3, 100 MHz) δ 165.8, 162.2, 133.1, 123.5, 123.3, 119.7, 113.0, 55.6, 52.1; MS (ESI) m/z Calculated value C9H9BrO3 (M+): 244.0, Measured value: 244.1 (M+).
