At room temperature, 3-bromo-4-(dibromomethyl)benzonitrile (8.80 g, 24.9 mmol) was dissolved in wet DMSO (83 mL), and the reaction mixture was subsequently heated to 120 °C and maintained for 6 hours. After completion of the reaction, it was cooled to room temperature, the reaction solution was diluted with water and transferred to a partition funnel and extracted with EtOAc. The organic phase was separated, washed with water and saturated NaCl aqueous solution sequentially, dried over Na2SO4 and filtered, and concentrated under reduced pressure to obtain a yellow solid. Finally, it was purified by silica gel column chromatography with 20:1 hexane/EtOAc as eluent to give 3-bromo-4-formylbenzonitrile (3.10 g, 14.8 mmol; 59.3% yield) as white solid.
