反应详情

A 20% solution of sodium ethoxide in ethanol (27.7 g) was combined at room temperature with diethyl malonate (13.0 g) and then with 4-(2,5-difluorophenyl)-3-buten-2-one (13.8 g) in portions. The reaction mixture was stirred at room temperature for 30 minutes and then heated with stirring for 2 hours. After allowing to stand to cool, the solvent was distilled off, and the residue was combined with water, and the aqueous layer was washed with ethyl acetate and concentrated. 2N Sodium hydroxide (42 ml) was added and the mixture was heated under reflux for 2 hours. After allowing to stand to cool, 2.5 M sulfuric acid (42 ml) was added over a period of 10 minutes, and then the mixture was heated under reflux for 3 hours. After allowing to stand to cool, the precipitated crystal was recovered by a filtration and washed successively with water and isopropyl ether to obtain 5-(2,5-difluorophenyl)cyclohexane-1,3-dione (11.6 g) as a colorless crystal.

1. temperatureheated
2. stirringwith stirring for 2 hours
3. temperatureto cool
4. distillationthe solvent was distilled off
5. washthe aqueous layer was washed with ethyl acetate
6. concentrationconcentrated
7. addition2N Sodium hydroxide (42 ml) was added
8. temperaturethe mixture was heated
9. temperatureunder reflux for 2 hours
10. temperatureto cool
11. addition2.5 M sulfuric acid (42 ml) was added over a period of 10 minutes
12. temperaturethe mixture was heated
13. temperatureunder reflux for 3 hours
14. temperatureto cool
15. filtrationthe precipitated crystal was recovered by a filtration
16. washwashed successively with water and isopropyl ether