THE SYNTHESIS OF NEW PODOPHYLLOTOXIN DERIVATIVES

The preparation of a number of podophyllotoxin derivatives, including four new compounds, is described. Reaction of 4-bromo-4'-demethyl-4-de oxypodophyllotoxin with EtOH and glycerol afforded the corresponding 4 -O-ethyl and 4-O-(2,3-dihydroxypropyl)-derivatives of 4'-demethylepipo dophyllotoxin. Treatment of the 4-O-ethyl derivative with phenyliodoni um diacetate in MeOH yielded a new quinone monoketal which underwent t ransketalization with ethylene glycol. Hydrolysis of the dimethyl keta l with aqueous acid afforded the corresponding ortho-quinone.