[CH2:1]([O:3][C:4]([C:6]1[CH:7]=[N:8][NH:9][CH:10]=1)=[O:5])[CH3:2].I[C:12]1[S:13][CH:14]=[CH:15][CH:16]=1.C(=O)([O-])[O-].[K+].[K+].BrCC>CS(C)=O.C(OCC)(=O)C.[Cu]>[CH2:1]([O:3][C:4]([C:6]1[CH:7]=[N:8][N:9]([C:12]2[S:13][CH:14]=[CH:15][CH:16]=2)[CH:10]=1)=[O:5])[CH3:2]1H-Pyrazole-4-carboxylic acid ethyl ester (7.0 g) and 2-iodothiophene (10.5 g) were dissolved in DMSO (50 mL), potassium carbonate (6.91 g) and copper powder (31.7 mg) were added, and the mixture was stirred at 150° C. for 6 hr. The reaction mixture was cooled to 80° C., bromoethane (2 mL) was added, and the mixture was stirred for 2 hr and cooled to room temperature. The reaction mixture was diluted with ethyl acetate. The organic layer was washed with water, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel chromatography (elution solvent; hexane:ethyl acetate=9:1) to give 1-(2-thienyl)-1H-pyrazole-4-carboxylic acid ethyl ester (2.23 g) as a white solid. The obtained compound was subjected to reactions in the same manner as in Reference Examples 17 to 18 to give the title compound.
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