Acetophenone → 3(5)-Ethyl-5(3)-phenylpyrazole

Participants

Reaction Steps

To a solution of acetophenone (10 g, 83 mmol) in anhydrous toluene (10 mL) was added LiHMDS (85.0 mL, 1.0 M in THF, 85.0 mmol) via syringe at 0° C. under argon. After 5 min, propionyl chloride (7.70 g, 83 mmol) was added in one portion via syringe. The ice bath was removed after 10 min and AcOH (2 mL), EtOH (50 mL), and hydrazine hydrate (8.35 g, 116 mmol) was added. The mixture was refluxed for 2 h. The resulting solution was added to 1.0 M NaOH solution, 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 yellowish liquid (12.05 g). LCMS m/z=173.3 [M+H]+; 1H NMR (400 MHz, DMSO-d6) δ ppm 1.23 (t, J=7.58 Hz, 3H), 2.64 (q, J=7.07 Hz, 2H), 6.46 (s, 1H), 7.20-7.52 (m, 3H), 7.77 (d, J=6.32 Hz, 2H), 12.55 (s, 1H).

Provenance & Evidence