تفاعل #58898

معادلة التفاعل

4-fluoro-N-methylbenzohydrazide

ethyl acetoacetate

→

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

المردود 44.0%

المذيبات

ethanol

ظروف التفاعل

المعالجة

1. 1
   درجة الحرارةwith heating
2. 2
   درجة الحرارةunder reflux
3. 3
   تركيزThe reaction mixture was concentrated
4. 4
   workup.ADDITIONwater was added
5. 5
   استخلاصthe mixture was extracted with ethyl acetate
6. 6
   غسيلThe organic layer was washed with water
7. 7
   تجفيفdried over anhydrous magnesium sulfate
8. 8
   تركيزconcentrated
9. 9
   أخرىto give an oil from a fraction
10. 10
    غسيلeluted 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
    درجة الحرارةwith heating
15. 15
    درجة الحرارةunder reflux
16. 16
    workup.ADDITIONWater was added to the reaction mixture
17. 17
    استخلاصthe mixture was extracted with ethyl acetate
18. 18
    غسيلThe organic layer was washed with water
19. 19
    تجفيفdried over anhydrous magnesium sulfate
20. 20
    تركيزconcentrated

الإجراء التجريبي

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.

المصدر