Isobutylmagnesium bromide (2M ether solution, 26.5 mL, 53 mmol) was slowly added dropwise to a solution of toluene (160 mL) containing 1-bromo-3-iodobenzene (10 g, 35.3 mmol) and tetrakis(triphenylphosphine)palladium(0) (1.1 g, 0.954 mmol) for a controlled time of 30 minutes at room temperature. During the reaction, the color of the mixture changed to green, and the reaction temperature needed to be controlled not to exceed 40°C. After the dropwise addition, the reaction mixture was continued to be stirred at room temperature for 3 hours. Subsequently, aqueous ammonium chloride solution (160 mL) was added to the reaction system, at which time the color of the reaction solution changed to red. The mixture was extracted with ether (2 x 100 mL) and the organic phases were combined. The organic phase was washed with aqueous ammonium chloride (100 mL), dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by distillation under reduced pressure and the fraction with a boiling point of 88 °C/25 mmHg was collected to give 1-bromo-3-isobutylbenzene (3.20 g, 42% yield). The structure of the product was confirmed by 1H-NMR (400 MHz, CDCl3): δ= 0.90 (d, 6H), 1.85 (m, 1H), 2.44 (d, 2H), 7.07 (d, 1H), 7.14 (t, 1H), 7.17 (m, 2H).
