4 -Demethyl-epi-podophyllotoxin

Di-0-dichloroacetyl-l-0-benzyloxycarbonyl-(4,6-0-ethylidene)-p-D-glucopyranose Palladium on carbon 4 -Demethyl-epi-podophyllotoxin Zinc acetate dihydrate Boron trifluoride etherate Trimethylsilyl trifluoromethane sulfonate Celite/basic alumina column... 

Demethyl-epi-podophyllotoxin (1 mmol) and 2,3-di-0-dichloroacetyl-(4,6-0-ethyiidene)-p-D-giucopyranose (2 mmol) were introduced into dry dichloromethane under anhydrous condition. When the temperature was stabilized to -20°C to -30°C, boron trifluoride etherate (1.5 mmol) was added slowly with stirring. Reaction was continued at this temperature and monitored by thin layer chromatography. After the completion of the reaction as evidenced by TLC, the solution was washed with water, dried over anhydrous sodium sulfate and concentrated under reduced pressure to afford the crude intermediate product 4 -demethyl-epi-podophyllotoxin-4-(2,3-di-0-dichloroacetyl-4,6-0-ethylidene)-p-D-glucopyranose. This crude product was then converted to etoposide by following the procedure as above described. The yield of final product etoposide was about 60%. 

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