N[C:2]1[C:3]([O:8][CH:9]([C:11]([O:13][CH3:14])=[O:12])[CH3:10])=[N:4][CH:5]=[CH:6][CH:7]=1.ClC(Cl)C.N([O:21][C:22]([CH3:25])(C)C)=O.CCCCC.C[O:32]CCOC>>[C:22]([O:21][C:2]1[C:3]([O:8][CH:9]([C:11]([O:13][CH3:14])=[O:12])[CH3:10])=[N:4][CH:5]=[CH:6][CH:7]=1)(=[O:32])[CH3:25]First, 1.5 ml of a boron trifluoride diethyl ether complex was added dropwise to a mixture of 1.1 g of 3-amino-2-{1-(methoxycarbonyl)ethoxy}pyridine, 1 ml of 1,2-dimethoxyethane, and 1 ml of dichloroethane at −10° C. After stirring at the same temperature for 10 minutes, a solution of 0.8 ml of t-butyl nitrite in 1 ml of 1,2-dimethoxyethane was added dropwise to the reaction mixture at −5° C. or lower. After stirring at the same temperature for 30 minutes, n-pentane was poured into the mixture. The lower one of the two layers separated was dissolved in acetic anhydride, and the solution was stirred at 70° C. for 1 hour. After the solvent was distilled out, the residue was subjected to silica gel chromatography to give 0.34 g of 3-acetoxy-2-{1-(methoxycarbonyl)ethoxy}pyridine.
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