3-Fluoro-4-methylaniline (5g, 39.95Immol) was dissolved in 10% sulfuric acid aqueous solution (100ml). Thereafter, the temperature was lowered to 0°C. thereto sodium nitrate (5.5g, 79.902mmol) was added, and the reaction mixture was stirred at same temperature for 30 minutes. Then the reaction mixture was stirred at 50°C for 30 minutes, and the last time, stirred at 80°C for 5 hours. Ice water was added to quench the reaction, and aqueous layer was extracted with ethyl acetate. Combined organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (n-hexane:ethyl acetate = 8:1) to give 2.26g (yield: 44.8%, colorless oil) of the target compound. 3-fluoro-4-methylphenol, yield 2.26g, 44.8% 1H NMR(400MHz, CDCl3): 6.98(1, J=8.6Hz, 1H), 6.52(m, 2H), 5.82(br, 1H), 2.12(s, 3H).
