Реакция #58898

Уравнение реакции

4-fluoro-N-methylbenzohydrazide

ethyl acetoacetate

→

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

Выход 44.0%

Растворители

ethanol

Условия реакции

Обработка

1. 1
   Температураwith heating
2. 2
   Температураunder reflux
3. 3
   КонцентрированиеThe reaction mixture was concentrated
4. 4
   workup.ADDITIONwater was added
5. 5
   Экстракцияthe mixture was extracted with ethyl acetate
6. 6
   ПромывкаThe organic layer was washed with water
7. 7
   Сушкаdried over anhydrous magnesium sulfate
8. 8
   Концентрированиеconcentrated
9. 9
   Другоеto give an oil from a fraction
10. 10
    Промывкаeluted 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
    Температураwith heating
15. 15
    Температураunder reflux
16. 16
    workup.ADDITIONWater was added to the reaction mixture
17. 17
    Экстракцияthe mixture was extracted with ethyl acetate
18. 18
    ПромывкаThe organic layer was washed with water
19. 19
    Сушкаdried over anhydrous magnesium sulfate
20. 20
    Концентрированиеconcentrated

Методика

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.

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