反应详情

55% Sodium hydride (2.6 g) was suspended in dimethoxyethane (150 ml). Ethyl diethylphosphonoacetate (9.6 ml) was added dropwise under nitrogen atmosphere under ice-cooling over five minutes, and the mixture was stirred at the same temperature for 45 minutes. A solution of tetrahydro-4H-pyran-4-one (4.0 g) in dimethoxyethane (10 ml) was added dropwise thereto over five minutes. The mixture was stirred at room temperature for 10 minutes and then heated under reflux for one hour. The reaction solution was poured into water, followed by extraction with ethyl acetate. The organic layer was washed with brine and then dried over anhydrous sodium sulfate, and the solvent was evaporated. The residue was purified by silica gel column chromatography (developed with ethyl acetate-hexane) to give the title compounds ethyl tetrahydro-4H-pyran-4-ylideneacetate (1.7 g) and ethyl 3,6-dihydro-2H-pyran-4-ylacetate (2.2 g) both as colorless oils.

1. temperaturecooling over five minutes
2. waitover five minutes
3. stirringThe mixture was stirred at room temperature for 10 minutes
4. temperatureheated
5. temperatureunder reflux for one hour
6. extractionfollowed by extraction with ethyl acetate
7. washThe organic layer was washed with brine
8. dry with materialdried over anhydrous sodium sulfate
9. customthe solvent was evaporated
10. customThe residue was purified by silica gel column chromatography (developed with ethyl acetate-hexane)