Reacción #58898

Ecuación de reacción

4-fluoro-N-methylbenzohydrazide

ethyl acetoacetate

→

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

Rendimiento 44.0%

Disolventes

ethanol

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturawith heating
2. 2
   Temperaturaunder reflux
3. 3
   ConcentraciónThe reaction mixture was concentrated
4. 4
   workup.ADDITIONwater was added
5. 5
   Extracciónthe mixture was extracted with ethyl acetate
6. 6
   LavadoThe organic layer was washed with water
7. 7
   Secadodried over anhydrous magnesium sulfate
8. 8
   Concentraciónconcentrated
9. 9
   Otroto give an oil from a fraction
10. 10
    Lavadoeluted 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
    Temperaturawith heating
15. 15
    Temperaturaunder reflux
16. 16
    workup.ADDITIONWater was added to the reaction mixture
17. 17
    Extracciónthe mixture was extracted with ethyl acetate
18. 18
    LavadoThe organic layer was washed with water
19. 19
    Secadodried over anhydrous magnesium sulfate
20. 20
    Concentraciónconcentrated

Procedimiento

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.

Fuente