Réaction #657253

Équation de réaction

ethyl 3-acetyl-4-oxopentanoate

hydrazine hydrate

→

pyrazole

Rendement 72.0%

Ethyl 2-(3,5-dimethyl-1H-pyrazol-4-yl)acetate

Rendement 72.0%

Solvants

ethanol

ethanol

Conditions de réaction

Traitement

1. 1
   AutreAfter removing ethanol under vacuum, dichloromethane and water
2. 2
   workup.ADDITIONwere added to the crude product
3. 3
   Autrethe organic layer was separated
4. 4
   ExtractionThe aqueous layer was extracted further with dichloromethane
5. 5
   Lavagethe combined organic extracts were washed with water
6. 6
   SéchageAfter drying over MgSO4 and evaporation of the solvent under reduced pressure

Mode opératoire

To a solution of ethyl 3-acetyl-4-oxopentanoate (synthesized as described D. P. Shrout and D. A. Lightner, Synth. Commun. 20 (1990), 2075) (9.676 g, 51.96 mmol) in ethanol, at 0° C., was added slowly a solution of hydrazine hydrate (2.990 g, 59.75 g) in absolute ethanol. The reaction mixture was warmed to room temperature and stirred for 2 hours. After removing ethanol under vacuum, dichloromethane and water were added to the crude product and the organic layer was separated. The aqueous layer was extracted further with dichloromethane and the combined organic extracts were washed with water. After drying over MgSO4 and evaporation of the solvent under reduced pressure, the pyrazole was isolated as a yellow oil. Yield: 72% (6.777 g, 37.2 mmol).

Source