反応 #657253

反応方程式

ethyl 3-acetyl-4-oxopentanoate

hydrazine hydrate

→

pyrazole

収率 72.0%

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

収率 72.0%

溶媒

ethanol

ethanol

反応条件

後処理

1. 1
   その他After removing ethanol under vacuum, dichloromethane and water
2. 2
   workup.ADDITIONwere added to the crude product
3. 3
   その他the organic layer was separated
4. 4
   抽出The aqueous layer was extracted further with dichloromethane
5. 5
   洗浄the combined organic extracts were washed with water
6. 6
   乾燥After drying over MgSO4 and evaporation of the solvent under reduced pressure

実験手順

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).

出典