反応 #1361484

反応方程式

dihydroartemisinin

methanol

boron trifluoride etherate

→

artemisinin

溶媒

chloroform

反応条件

後処理

1. 1
   温度slowly warmed up to room temperature
2. 2
   workup.STIRRINGstirred at room temperature for 3 hours
3. 3
   その他was consumed
4. 4
   その他The reaction mixture was quenched with water (50 mL)
5. 5
   workup.ADDITIONdiluted with chloroform (25 mL)
6. 6
   その他The two phases were separated
7. 7
   抽出the aqueous layer was extracted with chloroform (30×2 mL)
8. 8
   洗浄The combined organic layers were washed with brine
9. 9
   乾燥dried over magnesium sulfate
10. 10
    ろ過filtered
11. 11
    濃縮concentrated under reduced pressure
12. 12
    その他to afford crude product which
13. 13
    その他was further purified by column chromatography on Florisil (1%-10% EtOAc/hexanes)

実験手順

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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