反应详情

温度

80 °C

1-(Toluene-4-sulfonyl)-1H-indole-2,5-dicarboxylic acid 2-ethyl ester (690 mg, 1.85 mmol) was dissolved in N,N-dimethylformamide di-tert-butyl acetal (3.0 ml), and stirred at 80° C. for two and half hours. N,N-dimethylformamide di-tert-butyl acetal (2.0 ml) was further added thereto and stirred at 80° C. for three hours. After cooling to room temperature, the reaction mixture was diluted with ethyl acetate (150 ml) and water (75 ml). The organic layer was isolated, washed with water and a saturated aqueous solution of sodium chloride, and then dried over anhydrous sodium sulfate. The desiccant was removed by filtration. The filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (hexane/ethyl acetate=25/1 to 5/1) to give 1-(toluene-4-sulfonyl)-1H-indole-2,5-dicarboxylic acid 5-tert-butyl ester 2-ethyl ester (551 mg, 69%).

1. stirringstirred at 80° C. for three hours
2. temperatureAfter cooling to room temperature
3. customThe organic layer was isolated
4. washwashed with water
5. dry with materiala saturated aqueous solution of sodium chloride, and then dried over anhydrous sodium sulfate
6. customThe desiccant was removed by filtration
7. concentrationThe filtrate was concentrated under reduced pressure
8. customThe resulting residue was purified by silica gel column chromatography (hexane/ethyl acetate=25/1 to 5/1)