Under argon protection, 1-iodo-2,3-dimethoxybenzene (792 mg, 3.00 mmol) was dissolved in dichloromethane (10.0 mL) and cooled to -78°C. Boron tribromide (1.0 M solution in dichloromethane, 14.0 mL, 14.0 mmol) was added slowly, followed by warming the reaction mixture to room temperature and stirring for 42 hours. Upon completion of the reaction, the mixture was poured into ice water and the volatile components were removed under reduced pressure. The residue was extracted with ethyl acetate and the combined organic layers were washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was dissolved in N,N-dimethylformamide (30 mL), cesium carbonate (1.00 g, 3.07 mmol) and diiodomethane (250 μL, 3.10 mmol) were added, and stirred at 120 °C for 1 h under argon protection. After completion of the reaction, it was cooled to room temperature and N,N-dimethylformamide was removed under reduced pressure. Ethyl acetate and water were added to the residue, the insoluble material was removed by filtration and washed with ethyl acetate. The filtrate was extracted with ethyl acetate and the combined organic layers were washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (n-hexane/ethyl acetate=50:1) to afford 4-iodobenzo[d][1,3]dioxole (563 mg, 2.27 mmol, two-step yield 76%) as a white solid. Melting point: 35.5-37.0 °C; 1H NMR (CDCl3, 500 MHz) δ 7.11 (dd, J = 1.2, 8.6 Hz, 1H), 6.75 (dd, J = 1.2, 7.9 Hz, 1H), 6.78 (dd, J = 7.9, 8.6 Hz, 1H), 5.99 (s, 2H); MS (FAB) m/z 248 (M)+.
![4-IODOBENZO[D][1,3]DIOXOLE](/CAS/GIF/849517-65-3.gif)