反应详情

4.35 g (0.0665 At-g) of activated zinc are covered with 12 ml of dimethoxymethane, and then 1 ml (9 mmol) of pure ethyl bromoacetate is added under an argon atmosphere. After induction of the reaction by heating, a solution of 6.38 ml (57.5 mmol) of ethyl bromoacetate in 20 ml of dimethoxymethane is added in such a manner as to maintain reflux. After the zinc has been completely consumed and the reaction mixture has returned to room temperature, a solution of 11.1 g (43.5 mmol) of 3-acetyl-6-phenyl-2H-chromene in 60 ml of anhydrous tetrahydrofuran is added dropwise over a period of from 10 to 15 minutes. After one hour's stirring at room temperature, the mixture, cooled to +4° C., is treated with 25 ml of a 10% sulphuric acid solution. After addition of 70 ml of diethyl ether, the aqueous phase is separated off, and the ethereal phase is washed with 3×20 ml of water and then dried over magnesium sulphate. The solvents are evaporated off under reduced pressure, yielding a solid which is used in the following step without additional purification.

1. customAfter induction of the reaction
2. temperatureby heating
3. temperatureto maintain
4. temperaturereflux
5. customAfter the zinc has been completely consumed
6. customhas returned to room temperature
7. temperaturethe mixture, cooled to +4° C.
8. customthe aqueous phase is separated off
9. washthe ethereal phase is washed with 3×20 ml of water
10. dry with materialdried over magnesium sulphate
11. customThe solvents are evaporated off under reduced pressure
12. customyielding a solid which
13. customis used in the following step without additional purification