Water → Ethyl 4-azido-2-fluoro-3-methylbenzoate

In 47 ml of dimethyl sulfoxide was dissolved 4.65 g of ethyl 2,4-difluoro-3-methylbenzoate, followed by adding thereto 3.32 g of sodium azide, and the resulting mixture was stirred at 70° C. for 20 hours. The reaction mixture was cooled to room temperature and then added to a mixed solvent of 150 ml of toluene and 150 ml of water, and the organic layer was separated. The organic layer obtained was washed with water and then a saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, and then distilled under reduced pressure to remove the solvent. The resulting residue was purified by a column chromatography (eluent: toluene) to obtain 2.20 g of ethyl 4-azido-2-fluoro-3-methylbenzoate as a light-yellow oil.