Concentrated sulfuric acid (10 mL) was added dropwise to a stirred solution of methyl 2-iodobenzoate (5.0 g, 19.08 mmol, 1.0 eq.) and N-bromosuccinimide (NBS, 3.73 g, 20.99 mmol, 1.1 eq.) in acetic acid (10 mL), keeping the reaction temperature between 20-40 °C. The reaction mixture was stirred at room temperature for 88 hours and then warmed up to 50°C and continued stirring for 4 hours. Upon completion of the reaction, the mixture was cooled to 10 °C and the reaction was quenched with cold water (40 mL) and subsequently extracted with dichloromethane (DCM, 3 x 50 mL). The organic layers were combined and washed sequentially with 5% sodium bicarbonate solution (2 × 50 mL), 10% sodium sulfite solution (50 mL), and water (50 mL), then dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure to give the crude product methyl 5-bromo-2-iodobenzoate. The crude product was purified by rapid column chromatography on silica gel, the eluent being a hexane solution of 10% ethyl acetate. The pure grade was collected and the solvent was evaporated under reduced pressure to give methyl 5-bromo-2-iodobenzoate as an off-white solid (5 g, 77% yield). NMR hydrogen spectrum (400 MHz, CDCl3) δppm: 3.94 (s, 3H), 7.26-7.29 (m, 1H), 7.83 (d, J=8.4 Hz, 1H), 7.93 (d, J=8.8 Hz, 1H).
