Ammonium formate → 4-amino-1-(2-ethoxyethyl)-3-ethyl-1H-pyrazole-5-carboxamide

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A mixture of 1-(2-ethoxyethyl)-3-ethyl-4-nitro-1H-pyrazole-5-carboxamide from step 1 (5.70 g, 22 mmol) and palladium hydroxide (1.0 g) in ethanol (110 mL) was treated with ammonium formate (7.01 g, 111 mmol) in four unequal portions at about 10 minute intervals. The resulting mixture was heated under reflux for two hours and then cooled. The mixture was filtered through celite and concentrated. The resulting residue was purified by column chromatography on silica gel using a mixture of ethyl acetate and hexane as the eluent to provide 2.45 g of the title compound. 1H NMR (400 MHz, CDCl3): δ 1.17 (t, 3 H), 1.21-1.32 (m, 3 H), 2.60 (q, 2 H), 3.53 (q, 2 H), 3.79-3.95 (m, 2 H), 4.38-4.52 (m, 2 H). MS (ESI) m/z 227.

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