Cl[C:2]([O:4][CH2:5][CH3:6])=[O:3].[Br:7][C:8]1[C:14]([O:15][CH2:16][CH3:17])=[CH:13][C:11]([NH2:12])=[C:10]([F:18])[CH:9]=1.N1C=CC=CC=1>C(Cl)Cl>[Br:7][C:8]1[C:14]([O:15][CH2:16][CH3:17])=[CH:13][C:11]([NH:12][C:2](=[O:3])[O:4][CH2:5][CH3:6])=[C:10]([F:18])[CH:9]=1Ethyl chloroformate (2.15 g) was added dropwise to a solution of 4-bromo-5-ethoxy-2-fluoroaniline (4.21 g) and pyridine (2.84 g) in methylene chloride (36 ml) at 0° C., and the mixture was stirred at 10° C. for 3 hours. After the reaction, this was extracted with methylene chloride, then washed with diluted hydrochloric acid and an aqueous sodium hydrogencarbonate solution, and dried over anhydrous magnesium sulfate. Then, methylene chloride was distilled off, and the resulting crude crystals were crystallized from a mixed solvent of ethyl acetate and n-hexane (1:5 v/v) to obtain the objective ethyl N-(4-bromo-5-ethoxy-2-fluorophenyl)carbamate (5.30 g).
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