General procedure for the synthesis of 4-bromo-1-(bromomethyl)-2-iodobenzene (15b) from 4-bromo-2-iodo-1-methylbenzene: 4-bromo-2-iodotoluene (3.94 g, 13.3 mmol) was dissolved in 1,2-dichloroethane (19 mL) under nitrogen protection in a 50 mL two-necked round-bottomed flask and stirred at room temperature. Benzoyl peroxide (164 mg, 0.663 mmol) and N-bromosuccinimide (NBS, 2.63 g, 14.6 mmol) were then added sequentially and the reaction mixture was heated to reflux for 5 hours. After completion of the reaction, it was cooled to room temperature, the precipitate was collected by filtration and washed with hexane. The filtrate was dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure to give an orange solid. The solid was washed with cold methanol to give an off-white solid product (3.27 g, 8.75 mmol, 66% yield), which could be used for subsequent reactions without further purification. The structure of the product was confirmed by 1H-NMR (400 MHz, CDCl3): δ 8.01 (d, 1H, J = 2.0 Hz), 7.47 (dd, 1H, J = 8.3, 2.0 Hz), 7.33 (d, 1H, J = 8.3 Hz), 4.54 (s, 2H); High-resolution Mass Spectrometry (HRMS, EI) m/z calculated value C7H5Br2I [M+]: 377.7762, measured value: 377.7759.
