反应详情

A mixture of the compound obtained in step 1 (0.21 g) and 4N hydrogen chloride/ethyl acetate (5 mL) was stirred at room temperature for 3 hr. The precipitate was collected by filtration, and the aqueous layer was basified and extracted with ethyl acetate and aqueous sodium hydroxide solution. The organic layer was washed with saturated brine and dried, and the solvent was evaporated under reduced pressure. The residue was purified by basic silica gel column chromatography (solvent gradient; 0→40% ethyl acetate/hexane), and 4N hydrogen chloride/ethyl acetate was added. The precipitate was collected by filtration and recrystallized from ethanol-ethyl acetate to give the title compound (0.0050 g, 3%) as a white powder.

1. filtrationThe precipitate was collected by filtration
2. extractionextracted with ethyl acetate and aqueous sodium hydroxide solution
3. washThe organic layer was washed with saturated brine
4. customdried
5. customthe solvent was evaporated under reduced pressure
6. customThe residue was purified by basic silica gel column chromatography (solvent gradient; 0→40% ethyl acetate/hexane), and 4N hydrogen chloride/ethyl acetate
7. additionwas added
8. filtrationThe precipitate was collected by filtration
9. customrecrystallized from ethanol-ethyl acetate