4-FLUORO-2-METHOXYANILINE(551 mg, 3.90 mmol) is dissolved in dichloromethane (39.0 mL), concentrated sulfuric acid (1.85 mL) is added dropwise with stirring under ice-cooling, and then concentrated nitric acid (267 μL, 5.85 mmol) is added dropwise. After stirring for 3 hours under ice-cooling, saturated aqueous sodium bicarbonate was added until pH 8 was reached. After washing with saturated aqueous sodium bicarbonate solution, washing with saturated brine, the organic layer was dried over sodium sulfate and evaporated under reduced pressure to obtain 675 mg of the 4-fluoro-2-Methoxy-5-nitroaniline (yield 93%).
