反应详情

288 mg (1 mmole) of shikonin, 226 mg (1.1 mmole) of dicyclohexylcarbodiimide and 30 mg (0.25 mmole) of 4-dimethylaminopyridine were dissolved in 3 ml of dry dichloromethane. To the resulting solution was added 60 mg (1 mmole) of acetic acid at 0° C. under nitrogen gas, and the mixture was stirred for 30 minutes and then at room temperature for further 3 hours. 20 ml of n-hexane was added to the reaction solution. The mixture was filtered to remove the insoluble materials. The filtrate was dried and then concentrated under reduced pressure. The residue was purified with silica gel column chromatography (n-hexane: ethylacetate=20:1-5:1) to obtain 247 mg (Yield: 75%) of the title compound having the following structure as a red precipitate.

1. waitat room temperature for further 3 hours
2. filtrationThe mixture was filtered
3. customto remove the insoluble materials
4. customThe filtrate was dried
5. concentrationconcentrated under reduced pressure
6. customThe residue was purified with silica gel column chromatography (n-hexane: ethylacetate=20:1-5:1)