反応 #58898

反応方程式

4-fluoro-N-methylbenzohydrazide

ethyl acetoacetate

→

ethyl 5-(4-fluorophenyl)-1,3-dimethyl-1H-pyrazole-4-carboxylate

収率 44.0%

溶媒

ethanol

反応条件

後処理

1. 1
   温度with heating
2. 2
   温度under reflux
3. 3
   濃縮The reaction mixture was concentrated
4. 4
   workup.ADDITIONwater was added
5. 5
   抽出the mixture was extracted with ethyl acetate
6. 6
   洗浄The organic layer was washed with water
7. 7
   乾燥dried over anhydrous magnesium sulfate
8. 8
   濃縮concentrated
9. 9
   その他to give an oil from a fraction
10. 10
    洗浄eluted with hexane-ethyl acetate (4:1-1:1
11. 11
    workup.DISSOLUTIONThis oil was dissolved in ethanol (50 ml)
12. 12
    workup.ADDITION1,8-diazabicyclo[5.4.0]-7-undecene (0.5 ml) was added
13. 13
    workup.STIRRINGthe mixture was stirred for 4 hrs
14. 14
    温度with heating
15. 15
    温度under reflux
16. 16
    workup.ADDITIONWater was added to the reaction mixture
17. 17
    抽出the mixture was extracted with ethyl acetate
18. 18
    洗浄The organic layer was washed with water
19. 19
    乾燥dried over anhydrous magnesium sulfate
20. 20
    濃縮concentrated

実験手順

A mixture of 4-fluoro-N-methylbenzohydrazide (5.0 g), ethyl acetoacetate (4.84 g) and ethanol (140 ml) was stirred for 14 hrs. with heating under reflux. The reaction mixture was concentrated, water was added, and the mixture was extracted with ethyl acetate. The organic layer was washed with water, dried over anhydrous magnesium sulfate and concentrated. The residue was subjected to silica gel column chromatography to give an oil from a fraction eluted with hexane-ethyl acetate (4:1-1:1, v/v). This oil was dissolved in ethanol (50 ml), 1,8-diazabicyclo[5.4.0]-7-undecene (0.5 ml) was added, and the mixture was stirred for 4 hrs. with heating under reflux. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with water, dried over anhydrous magnesium sulfate and concentrated to give ethyl 5-(4-fluorophenyl)-1,3-dimethyl-1H-pyrazole-4-carboxylate (3.41 g, yield 44%) as colorless crystals.

出典