4-Bromo-3-methoxyaniline (102 mg, 0.50 mmol) was used as starting material and dissolved in concentrated hydrochloric acid (10 mL) at 0 °C. Subsequently, an aqueous solution of sodium nitrite (NaNO2, 45 mg, 0.65 mmol) (5 mL) was slowly added, the reaction temperature was maintained at 0 °C and the reaction was stirred for 1 hour. Next, an aqueous solution of potassium iodide (KI, 249 mg, 1.5 mmol) (5 mL) was added, and the reaction mixture was gradually warmed to room temperature and stirred overnight. After completion of the reaction, the product was extracted with ethyl acetate. The organic phase was washed sequentially with water and 10% sodium thiosulfate (Na2S2O3) solution, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated to give 147 mg of 2-bromo-5-iodoanisole in 94% yield. The product was analyzed by mass spectrometry (ESI), m/e 332 (M + 20)+; nuclear magnetic resonance hydrogen spectrum (1H NMR, 300 MHz, DMSO-d6) δ 7.39 (d, J = 1.87 Hz, 1H), 7.34 (d, J = 8.11 Hz, 1H), 7.24 (dd, J = 8.11, 1.87 Hz, 1H), 3.86 (s 3H).
