[OH-].[K+].Cl.[NH2:4]O.[C:6]([C:10]1[N:14]([CH3:15])[N:13]=[C:12](C2C=C(C)NC=2C)[CH:11]=1)([O:8][CH3:9])=[O:7]>O.C(O)C>[C:6]([C:10]1[N:14]([CH3:15])[N:13]=[C:12]([NH2:4])[CH:11]=1)([O:8][CH3:9])=[O:7]
A solution of potassium hydroxide (5.08 g, 90.7 mmol) in water (76 mL) and ethanol (76 mL) was added to a slurry of hydroxylamine hydrochloride (11.44 g, 169.5 mmol) in ethanol (127 mL). Then, 5-carbomethoxy-3-(2,5-dimethylpyrrolyl)-1-methylpyrazole (8.5 g, 36.6 mmol) was added and the mixture was refluxed under a nitrogen atmosphere for 65 h. The solvents were removed at reduced pressure and the residue was triturated with ether. Sodium sulfate was added and the heterogenous mixture was filtered. The filtrate was concentrated and the residue was chromatographed on Silica Woelm®TSC (300 g, ethyl acetate-hexane gradient) to give 4.61 g, 81% of 5-carbomethoxy-3-amino-1-methylpyrazole as a white solid mp 114° to 118° C.; 1H-NMR (CDCl3) σ 6.17 (s, 1H), 4.02 (s, 3H), 3.88 (s, 1H), 3.7 (br s, 2H); IR (KBr) 1719, 1551, 1263, 1102, 756 cm-1.
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