Methyl 3-chloro-2-methylbenzoate (1 g, 5.42 mmol) was used as a raw material, which was mixed with carbon tetrachloride (13.3 ml), N-bromosuccinimide (1.06 g, 5.96 mmol) and benzoyl peroxide (3.5 mg, 0.0108 mmol) to form a suspension. The reaction mixture was heated in an oil bath at 90°C under nitrogen protection. After the reaction was carried out for 3 hours and 45 minutes, the heating was stopped. The reaction solution was sequentially diluted with water, ethyl acetate and saturated aqueous sodium bicarbonate. The organic layer was separated, washed with saturated aqueous sodium bicarbonate solution, dried over anhydrous magnesium sulfate, filtered and concentrated to afford the target product methyl 2-bromomethyl-3-chloro-benzoate (1.43 g, yield: 100%). The product was characterized by 1H-NMR (400 MHz, CDCl3) with chemical shifts δppm of 4.00 (3H, s), 5.12 (2H, s), 7.32 (1H, t, J = 8 Hz), 7.58 (1H, dd, J = 2,8 Hz), 7.86 (1H, dd, J = 2,8 Hz), respectively.
