Natural products as sources of new fungicides: synthesis and antifungal activity of zopfiellin analogues.

The synthesis of a series of cyclooctadiene anhydrides, analogues of the natural compound zopfiellin, was performed to assay their in vitro and in vivo antifungal activity on a set of plant pathogenic fungi. Most of the synthesized compounds possessed a broad spectrum of activity. In particular, the anhydrides 2 and 5a were very effective against the Oomycete diseases such as Phytophthora infestans and Pythium ultimum, reaching a level of activity well comparable with that of commercial fungicides in use. Preliminary in vivo evaluation of their protectant activity is also reported.