Hydrazine hydrate (1:1) → 3-Phenyl-5-(trifluoromethyl)-1H-pyrazole

Participants

Reaction Steps

To a stirred mixture of 4,4,4-trifluoro-1-phenylbutane-1,3-dione (5.0 g, 23.13 mmol) in dry ethanol (100 mL) was added hydrazine hydrate (1.737 g, 34.7 mmol) dropwise. The resulting solution was refluxed for 16 h. The reaction was cooled to room temperature and concentrated. The oil was diluted with saturated NaHCO3 solution and extracted with EtOAc, washed with brine, dried over MgSO4 and concentrated. The residue was purified by silica gel column chromatography to give the title compound as a clear liquid which was crystallized in hexanes/ethyl acetate (3.25 g). LCMS m/z=213.1 [M+H]+; 1H NMR (400 MHz, CDCl3) δ ppm 6.77 (s, 1H), 7.36-7.51 (m, 3H), 7.53-7.64 (m, 2H), 11.59 (s, 1H).

Provenance & Evidence