Реакция #1361484

Уравнение реакции

dihydroartemisinin

methanol

boron trifluoride etherate

→

artemisinin

Растворители

chloroform

Условия реакции

Обработка

1. 1
   Температураslowly warmed up to room temperature
2. 2
   workup.STIRRINGstirred at room temperature for 3 hours
3. 3
   Другоеwas consumed
4. 4
   ДругоеThe reaction mixture was quenched with water (50 mL)
5. 5
   workup.ADDITIONdiluted with chloroform (25 mL)
6. 6
   ДругоеThe two phases were separated
7. 7
   Экстракцияthe aqueous layer was extracted with chloroform (30×2 mL)
8. 8
   ПромывкаThe combined organic layers were washed with brine
9. 9
   Сушкаdried over magnesium sulfate
10. 10
    Фильтрацияfiltered
11. 11
    Концентрированиеconcentrated under reduced pressure
12. 12
    Другоеto afford crude product which
13. 13
    Другоеwas further purified by column chromatography on Florisil (1%-10% EtOAc/hexanes)

Методика

To a solution of the crude dihydroartemisinin in chloroform (40 mL) and methanol (1 mL, 24.8 mmol) was added boron trifluoride etherate (0.16 mL, 1.24 mmol) at 0° C. The reaction was stirred at 0° C. for 15 minutes, slowly warmed up to room temperature and stirred at room temperature for 3 hours. The reaction was monitored by TLC until all starting material was consumed. The reaction mixture was quenched with water (50 mL) and diluted with chloroform (25 mL). The two phases were separated, and the aqueous layer was extracted with chloroform (30×2 mL). The combined organic layers were washed with brine, dried over magnesium sulfate, filtered and concentrated under reduced pressure to afford crude product which was further purified by column chromatography on Florisil (1%-10% EtOAc/hexanes) to give two artemisinin isomers as white solids: β-isomer (0.29 g, 0.98 mmol, 79%) mp 73°-74.5° C.; α-isomer (0.05 g, 0.17 mmol, 14%), with each having a 1H NMR spectrum identical to that reported in the literature. ##STR33##

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