omocamptothecin was prepared by a novel total synthetic method in five steps from the tricyclic starting material 2,8-dioxo-3-ethyl-6,6-ethylenedioxy-2,3,5,6,7,8-hexahydro-3-hydroxypyrano(5,4- c)indolizine. Hydrogen peroxide oxidized homocamptothecin with methanol to form 10-hydroxymethyl- homocamptothecin, which then reacted with a series of acids to afford six 10-ester derivatives of homocamptothecin. Their structures were characterized by ¹H NMR, MS spectra and elemental analysis. Antitumor activity tests in vitro by MTT method indicated that three compounds possessed higher inhibiting activity against A-549, LOVO and MCF-7 cell lines than topotecan.

Key words: total synthesis, antitumor activity, 10-ester-homocamptothecin