Reaktion #657253

Reaktionsgleichung

ethyl 3-acetyl-4-oxopentanoate

hydrazine hydrate

→

pyrazole

Ausbeute 72.0%

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

Ausbeute 72.0%

Lösungsmittel

ethanol

ethanol

Reaktionsbedingungen

Aufarbeitung

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

Vorschrift

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).

Quelle