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

To a solution of acetophenone (10 g, 83 mmol) in anhydrous toluene (10 mL) 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) were 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).

1. customThe ice bath was removed after 10 min
2. temperatureThe mixture was refluxed for 2 h
3. extractionextracted with EtOAc
4. washwashed with brine
5. dry with materialdried over MgSO4
6. concentrationconcentrated
7. customThe residue was purified by silica gel column chromatography

ORD record

ord-e54bd48c72a0418c99e941cfc566eaa5

Source dataset

uspto-grants-2015_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09012478B2