反应详情

Combine 6-carboxy-1H-indole and ethanol (110 ml) and cool to 5° C. Add dropwise concentrated H2SO4 (96%, 11.08 ml) while keeping the temperature below 10° C. Heat to reflux. After 4 hours, cool and pour onto ice/water, adjust the pH to about pH 9 and extract with ethyl acetate. Combine the organic extracts, wash with brine, dry Na2SO4), then concentrate to residue. Chromatograph the residue on silica gel eluting with chloroform to give, after evaporation, the title compound: mp 72-75° C. MS (ACPI): m/e 189.9 (M+1).

1. customthe temperature below 10° C
2. temperatureHeat to reflux
3. temperaturecool
4. additionpour onto ice/water
5. extractionextract with ethyl acetate
6. washwash with brine, dry Na2SO4),
7. concentrationthen concentrate to residue
8. customChromatograph the residue on silica gel eluting with chloroform to give
9. customafter evaporation