[NH2:1][NH2:2].[CH3:3][O:4][C:5]1[CH:10]=[CH:9][C:8]([C:11](=O)[CH2:12][C:13](=O)[C:14]([O:16][CH2:17][CH3:18])=[O:15])=[CH:7][CH:6]=1>C(O)C>[CH3:3][O:4][C:5]1[CH:10]=[CH:9][C:8]([C:11]2[CH:12]=[C:13]([C:14]([O:16][CH2:17][CH3:18])=[O:15])[NH:1][N:2]=2)=[CH:7][CH:6]=11.52 ml (31.28 mmol) of hydrazine was added to an ethanol solution (50 ml) of 7.12 g (28.44 mmol) of the obtained ethyl 4-(4-methoxyphenyl)-2,4-dioxobutyrate, and then the reaction liquid was stirred at 60° C. for 4 hours. The reaction liquid was concentrated under reduced pressure, and the resulting solid was washed with diethyl ether to obtain 6.76 g (yield: 96%) of ethyl 5-(4-methoxyphenyl)-2H-pyrazole-3-carboxylate as a white solid.
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