[Synthesis and antitumor activity of 4-alkylthio-4-deoxy-4'-demethylepipodophyllotxin derivatives]

As a continuing part of our study on the chemistry and antitumor activity of podophyllotoxin, 11 new C-4 S-substituted podophyllotoxin derivatives were synthesised and screened in vitro against L1210 leukemia and KB cells. Thus, 4'-demethylepipodophyllotoxin was reacted with thiols in the presence of BF3. Et2O or trifluroacetic acid to give thioethers. In addition, 4-bromo-4-deoxy-4'-demethylepipodophyllotoxin, when reacted with thiols, also gave rise to corresponding thioether (4-alkylthio-4-deoxy-4'-demethylepipodophyllotoxins). Compounds 10 and 12 have the same activity as etoposide in the inhibition against L1210 leukemia, and compounds 9, 10, 12 and 15 also have comparable activity with etoposide against KB cells.