In 90 ml of N,N-dimethylformamide was dissolved 9.0 g of methyl 4-(1-carboxycyclopropyl)-2,3,5,6-tetrafluorobenzoate. To the resulting solution were added, with ice-cooling, 4.0 g of ethyl chlorocarbonate and 3.7 g of triethylamine in this order. The resulting mixture was stirred at the same temperature for 30 minutes. Then, 2.6 g of sodium azide was added thereto with ice-cooling. The resulting mixture was stirred at the same temperature for 1 hour. To the reaction mixture were added 150 ml of ethyl acetate and 300 ml of water in this order. The resulting mixture was adjusted to pH 1 with 2N hydrochloric acid. The organic layer was separated, washed with water and a saturated aqueous sodium chloride solution in this order, and dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure. The residue obtained was dissolved in a mixture of 90 ml of dioxane and 8.1 g of benzyl alcohol. The resulting solution was refluxed for 1 hour. The reaction mixture was concentrated under reduced pressure. The residue obtained was purified by a column chromatography (eluant: toluene) to obtain 10.6 g (yield: 86.9%) of methyl 4-(1-benzyloxycarbonylaminocyclopropyl)-2,3,5,6-tetrafluorobenzoate.
