反应详情

To a solution of 5-(2,5-dichlorothiophen-3-yl)cyclohexane-1,3-dione (3.07 g), 4-dimethylaminopyridine (2.14 g) and dicyclohexylcarbodiimide (3.13 g) in dimethylformamide (10 ml) was added acetic acid (1.26 g), and the mixture was stirred at room temperature for 13 hours. To the mixture were added water (30 ml) and 2N hydrochloric acid (10 ml), and the mixture was extracted with ethyl acetate. The organic layer was extracted with 0.5N sodium hydroxide solution, and to the aqueous layer was added 2N hydrochloric acid to make the solution acidic. The solution was extracted with ethyl acetate, and the organic layer was washed with water. Under reduced pressure, the solvent was evaporated, and the residue was recrystallized from ethyl acetate-hexane to give 5-(2,5-dichlorothiophen-3-yl)-2-(1-hydroxyethylidene)cyclohexane-1,3-dione (2.5 g) as yellow crystals.

1. extractionthe mixture was extracted with ethyl acetate
2. extractionThe organic layer was extracted with 0.5N sodium hydroxide solution
3. additionto the aqueous layer was added 2N hydrochloric acid
4. extractionThe solution was extracted with ethyl acetate
5. washthe organic layer was washed with water
6. customUnder reduced pressure, the solvent was evaporated
7. customthe residue was recrystallized from ethyl acetate-hexane