Reaktion #58898

Reaktionsgleichung

4-fluoro-N-methylbenzohydrazide

ethyl acetoacetate

→

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

Ausbeute 44.0%

Lösungsmittel

ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwith heating
2. 2
   Temperaturunder reflux
3. 3
   EinengenThe reaction mixture was concentrated
4. 4
   workup.ADDITIONwater was added
5. 5
   Extraktionthe mixture was extracted with ethyl acetate
6. 6
   WaschenThe organic layer was washed with water
7. 7
   Trocknendried over anhydrous magnesium sulfate
8. 8
   Einengenconcentrated
9. 9
   Sonstigeto give an oil from a fraction
10. 10
    Wascheneluted 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
    Temperaturwith heating
15. 15
    Temperaturunder reflux
16. 16
    workup.ADDITIONWater was added to the reaction mixture
17. 17
    Extraktionthe mixture was extracted with ethyl acetate
18. 18
    WaschenThe organic layer was washed with water
19. 19
    Trocknendried over anhydrous magnesium sulfate
20. 20
    Einengenconcentrated

Vorschrift

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.

Quelle