[CH2:1]([O:8][C:9]([C:11]1[CH:12]=[C:13]2[C:17](=[CH:18][CH:19]=1)[NH:16][CH:15]=[C:14]2[CH:20]=O)=[O:10])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.Cl.[NH2:23]O.C(OC(=O)C)(=O)C.[OH-].[Na+]>O1CCCC1.N1C=CC=CC=1>[CH2:1]([O:8][C:9]([C:11]1[CH:12]=[C:13]2[C:17](=[CH:18][CH:19]=1)[NH:16][CH:15]=[C:14]2[C:20]#[N:23])=[O:10])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1To a solution of 3-formyl-1H-indole-5-carboxylic acid benzyl ester (4.3 g) and pyridine (4.8 g) in tetrahydrofuran (60 ml) was added hydroxylamine hydrochloride (1.6 g) at room temperature and this mixture was stirred at 80° C. overnight. Acetic anhydride was added to reaction mixture at the same temperature and this mixture was stirred for 8 hours. After cooling to ambient temperature, 1 mol/L sodium hydroxide solution (20 mL) was added to this mixture and resulting mixture was extracted with diethyl ether. The organic layer was washed with brine, and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure and this residue was purified by column chromatography on silica gel (eluent: n-hexane/ethyl acetate) to give the title compound (2.8 g).
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