反应详情

A stream of nitrogen gas is passed through a mixture of 19.6 ml (41.2 mmol) of 2.1M vinyllithium in tetrahydrofuran and 21 ml toluene to evaporate tetrahydrofuran. The resulting pale yellow suspension is diluted with 21 ml ether and cooled to -78°. To this solution is added 1.87 g (20.9 mmol) cuprous cyanide and the reaction mixture is then warmed to 0° for 2 min. The resulting gray suspension is cooled to -78° and 0.9 ml (10.4 mmol) of 5,6-dihydro-2H-pyran-2-one is added. The reaction mixture is stirred at -78° for 30 min and at -20° for 15 min. The reaction is quenched by the addition of saturated aqueous ammonium chloride and stirred for 1 h at room temperature. The insoluble salts are filtered off and washed with water (1×20 ml) and ether (2×20 ml). The layers are separated and the aqueous phase is extracted with ether (2×30 ml). Combined organic extracts are dried (MgSO4), filtered and evaporated to give a yellow oil which is purified by flash chromatography to obtain 4-ethenyltetrahydro-2H-pyran-2-one as a pale yellow oil.

1. customto evaporate tetrahydrofuran
2. additionThe resulting pale yellow suspension is diluted with 21 ml ether
3. temperaturecooled to -78°
4. temperaturethe reaction mixture is then warmed to 0° for 2 min
5. temperatureThe resulting gray suspension is cooled to -78°
6. customThe reaction is quenched by the addition of saturated aqueous ammonium chloride
7. stirringstirred for 1 h at room temperature
8. filtrationThe insoluble salts are filtered off
9. washwashed with water (1×20 ml) and ether (2×20 ml)
10. customThe layers are separated
11. extractionthe aqueous phase is extracted with ether (2×30 ml)
12. dry with materialCombined organic extracts are dried (MgSO4)
13. filtrationfiltered
14. customevaporated
15. customto give a yellow oil which
16. customis purified by flash chromatography