[CH3:1][N:2]1[CH:6]=[C:5]([N+:7]([O-:9])=[O:8])[C:4]([C:10]([OH:12])=O)=[N:3]1.[CH3:13][N:14](C(ON1N=NC2C=CC=CC1=2)=[N+](C)C)[CH3:15].[B-](F)(F)(F)F.Cl.CNC.C(N(CC)C(C)C)(C)C>CN(C=O)C>[CH3:13][N:14]([CH3:15])[C:10]([C:4]1[C:5]([N+:7]([O-:9])=[O:8])=[CH:6][N:2]([CH3:1])[N:3]=1)=[O:12]A solution of 1-methyl-4-nitro-1H-pyrazole-3-carboxylic acid (500 mg, 2.92 mmol) in DMF (5 ml) under inert gas atmosphere was treated with TBTU (1030 mg, 3.2 mmol), dimethylamine hydrochloride (262 mg, 3.2 mmol) and N,N-diisopropylethylamine (2.0 ml, 11.7 mmol) and stirring was continued for 4 h. All volatiles were removed and the crude product was extracted with water and ethyl acetate. The organic phase was washed with sodium bicarbonate and the aqueous phases were back-extracted with ethyl acetate and dichloromethane. The combined organic phases were dried and the solvent was evaporated. The product was obtained after purification by silica gel chromatography using a dichloromethane/methanol gradient as white solid (230 mg, 40%).
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