(+-)-Methionine → (-)-4'-Demethylepipodophyllotoxin

Participants

Reaction Steps

A solution of 50 g (0.12 mol) of podophyllotoxin I, prepared in 50 ml of acetone, is added with stirring at ordinary temperature to a mixture consisting of 100 g (0.67 mol) of D,L-methionine, of 500 ml (7.7 mol) of methanesulfonic acid and of 10 ml of water. The temperature rises to approximately 40° C. and stirring is maintained for 2 h with return to ambient temperature. The mixture is then poured onto ice in order to obtain a precipitate which is extracted with ethyl acetate (3×700 ml). The organic phases are washed with an NaHCO3 solution and then separated by settling, dried over Na2SO4, filtered and evaporated under reduced pressure in order to obtain 4'-demethylepipodophyllotoxin, existing in the form of a white solid. 45 g (Yd 94%) are obtained.

Provenance & Evidence