[NH2:1]/[C:2](/OCC)=[CH:3]\[C:4](=O)[C:5]([F:8])([F:7])[F:6].[NH2:13][NH2:14]>CCO>[F:6][C:5]([F:8])([F:7])[C:4]1[NH:14][N:13]=[C:2]([NH2:1])[CH:3]=1A mixture of (E)-4-amino-4-ethoxy-1,1,1-trifluorobut-3-en-2-one (5.00 g, 27 mmol) and hydrazine (1.05 g) in anhydrous EtOH (20 mL) was stirred at 80° C. in a sealed vial overnight. The reaction was quenched with water (50 mL), and extracted with EtOAc (100 ml, then 2×50 mL). The EtOAc layers were combined and sequentially washed with water (25 mL), brine (25 mL), dried over Na2SO4 and evaporated to give a light brown oily residue. The crude product was purified by silica chromatography (30-100% EtOAc in hexanes gradient) to give 5-(trifluoromethyl)-1H-pyrazol-3-amine as an off white solid; ESMS m/z 152.0 (M+H+).
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