Hydrazine hydrate (1:1) → Ethyl 3-(4-fluorophenyl)-1h-pyrazole-5-carboxylate

Participants

Reaction Steps

To a solution of Intermediate 1A (120 g, 504 mmol) in ethanol (1200 mL) was added hydrazine monohydrate (25.7 mL, 529 mmol) slowly and the resulting reaction mixture was refluxed for 1 h. Reaction mixture was cooled to RT, poured into ice cold water, and the resultant solid dried under vacuum to afford Intermediate 1B (80 g, 67%). MS(ES): m/z=235 [M+H]+; 1H NMR (300 MHz, CDCl3) δ ppm 7.75 (m, 2H), 7.12 (m, 2H), 7.07 (s, 1H), 4.42 (q, J=7.2 Hz, 2H), 1.42 (t, J=7.2 Hz, 3H).

Provenance & Evidence