反应详情

温度

70 °C

To a 2 L isopropanol solution of ethyl 6-benzyloxy-2-ethylchromane-2-carboxylate (155 g, 0.455 mol) was added 1 L of aqueous 5N sodium hydroxide. This solution was heated to 70° C. overnight. Isopropanol was removed under reduced pressure. The residue was acidified with conc. hydrochloric acid 300 ml and 2N hydrochloric acid to pH 1. The acidic solution was extracted three times with AcOEt. The combined organic layers were dried over anhydrous Na2SO4, filtered, concentrated to give a yellow oil, which crystallized upon standing: 130 g (91%).

1. customIsopropanol was removed under reduced pressure
2. extractionThe acidic solution was extracted three times with AcOEt
3. dry with materialThe combined organic layers were dried over anhydrous Na2SO4
4. filtrationfiltered
5. concentrationconcentrated
6. customto give a yellow oil, which
7. customcrystallized