Dimethyl Sulfide → (-)-4'-Demethylepipodophyllotoxin

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Reaction Steps

10 g (24 nmol) of podophyllotoxin are dissolved in 60 ml of trifluoroacetic acid. There are successively added 5.4 ml (72 mmol) of methanesulfonic acid. Stirring is carried out for 9 hours, 5.4 ml (72 mmol) of dimethyl sulfide are again added and stirring is carried out for 9 hours. The mixture is discharged onto ice (600 ml) and extracted with ethyl acetate (3×300 ml). The organic phases are washed with water and then with NaHCO3 solution until neutral. After drying over sodium sulfate, filtration and evaporation, there are obtained 6.3 g of 4′-demethylepipodophyllotoxin, which is used directly in the next step.

Provenance & Evidence