A mixture of 774 mg of ethyl 1-aminocyclopropane-1-carboxylate hydrochloride, 1.4 mL of triethylamine, and 15 mL of dichloromethane was stirred at room temperature for 30 minutes, and 15 mL of pyridine and 1.50 g of 2-(trimethylsilyl)ethyl 3-(chlorosulfonyl)benzoate were added thereto in this order, followed by stirring at room temperature overnight. The reaction mixture was concentrated under reduced pressure, and to the residue was added an aqueous citric acid solution, followed by extraction with ethyl acetate. The organic layer was washed with saturated brine, then dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane-ethyl acetate) to obtain 1.80 g of 2-(trimethylsilyl)ethyl 3-{[1-(ethoxycarbonyl)cyclopropyl]sulfamoyl}benzoate as a pale yellow oily substance.
