反应详情

5-Hydroxy-1H-2-indolecarboxylic acid (328 mg) was dissolved in ethanol (10 ml) to prepare a solution. Concentrated sulfuric acid was added to the solution, and the mixture was heated under reflux for 3 hr. The reaction solution was cooled to room temperature, an aqueous sodium hydrogencarbonate solution was then added thereto, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was then washed with saturated brine and was dried over anhydrous magnesium sulfate. The solvent was removed therefrom by distillation under the reduced pressure, and the residue was purified by column chromatography on silica gel using ethyl acetate-hexane to give ethyl 5-hydroxy-1H-2-indolecarboxylate (336 mg, yield 88%).

1. customto prepare a solution
2. temperaturethe mixture was heated
3. temperatureunder reflux for 3 hr
4. extractionthe mixture was extracted with ethyl acetate
5. washThe ethyl acetate layer was then washed with saturated brine
6. dry with materialwas dried over anhydrous magnesium sulfate
7. customThe solvent was removed
8. distillationby distillation under the reduced pressure
9. customthe residue was purified by column chromatography on silica gel