[N+:1]([C:4]1[CH:5]=[N:6][NH:7][CH:8]=1)([O-:3])=[O:2].[C:9]([O:13][C:14](=[O:19])[NH:15][CH2:16][CH2:17]Br)([CH3:12])([CH3:11])[CH3:10].C(=O)([O-])[O-].[Cs+].[Cs+].O>CN(C)C=O>[C:9]([O:13][C:14](=[O:19])[NH:15][CH2:16][CH2:17][N:6]1[CH:5]=[C:4]([N+:1]([O-:3])=[O:2])[CH:8]=[N:7]1)([CH3:12])([CH3:11])[CH3:10]To a solution of 4-nitro-1H-pyrazole (5.0 g) in N,N-dimethylformamide (100 mL) were added tert-butyl(2-bromoethyl)carbamate (12 g) and cesium carbonate (19 g), and the mixture was stirred overnight at 40° C. To the reaction mixture was added water, and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with water and saturated brine, and dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate) to give the title compound (13 g).
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