[Synthesis]
To a stirred solution of 3-bromo-2-chlorobenzoic acid (6 g, 25.64 mmol) in N,N-dimethylformamide (DMF, 30 mL) at 0 °C were sequentially added potassium carbonate (K2CO3, 5.2 g, 38.46 mmol) and iodomethane (CH3I, 5.47 g, 38.46 mmol). The reaction mixture was gradually warmed up to room temperature and stirred continuously for 1 hour. After completion of the reaction, the reaction mixture was diluted with cold water and stirring was continued for 10 minutes. The resulting precipitate was collected by filtration and dried under vacuum to afford methyl 3-bromo-2-chlorobenzoate (5.8 g, yield: 92%, 99.5% purity by LC-MS).1H NMR (400 MHz, CDCl3) δ 7.75 (dd, J = 8.0 Hz, J = 1.6 Hz, 1H), 7.68 (dd, J = 7.6 Hz, J = 1.6 Hz. 1H), 7.18 (t, J = 7.8 Hz, 1H), 3.94 (s, 3H). |