反应详情

A mixture of 3-(dimethylamino)-1-(2-thienyl)prop-2-en-1-one (193 mmol) and hydrazine hydrate (396 mmol) in 50 mL ethanol was refluxed for 18 h and then allowed to cool to room temperature. The solvent was evaporated under reduced pressure and the residue was partitioned between ethyl acetate and water. The organic phase was successively washed with saturated aqueous ammonium chloride solution, saturated aqueous sodium bicarbonate solution and brine, dried over MgSO4, filtered and concentrated. The residue was recrystallized (dichloromethane/cyclohexane) to afford 26.0 g 3-(2-thienyl)-1H-pyrazole (90% yield).

1. temperaturewas refluxed for 18 h
2. customThe solvent was evaporated under reduced pressure
3. customthe residue was partitioned between ethyl acetate and water
4. washThe organic phase was successively washed with saturated aqueous ammonium chloride solution, saturated aqueous sodium bicarbonate solution and brine
5. dry with materialdried over MgSO4
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was recrystallized (dichloromethane/cyclohexane)