反应详情

To a 5 L acetone solution of ethyl 7-hydroxy-chromane-2-carboxylate (630.1 g, 2.84 mol) was added potassium carbonate powder (785 g, 5.68 mol) and benzyl bromide (405 ml, 3.41 mol). The resulting suspension was heated to reflux for 16 hr. The reaction mixture was filtered through a pad of celite. The filtrate was concentrated to give solid material, which was re-dissolved in AcOEt, washed with water to remove residual salt, dried over MgSO4, filtered, concentrated to a small volume. Addition of hexanes caused precipitation of the title compound, which was collected by suction-filtration. The filtrate was triturated from dichloromethane-hexanes to give more precipitates. Finally the filtrate was concentrated and chromatographed on silica gel eluting with 20 to 80% dichloromethane/hexanes. Combination of all crops yielded the title compound 760.2 g as off-white solid (86%).

1. temperatureThe resulting suspension was heated
2. temperatureto reflux for 16 hr
3. filtrationThe reaction mixture was filtered through a pad of celite
4. concentrationThe filtrate was concentrated
5. customto give solid material, which
6. washwashed with water
7. customto remove residual salt
8. dry with materialdried over MgSO4
9. filtrationfiltered
10. concentrationconcentrated to a small volume
11. additionAddition of hexanes
12. customprecipitation of the title compound, which
13. filtrationwas collected by suction-filtration
14. customThe filtrate was triturated from dichloromethane-hexanes
15. customto give more
16. customprecipitates
17. concentrationFinally the filtrate was concentrated
18. customchromatographed on silica gel eluting with 20 to 80% dichloromethane/hexanes