Synthesis, Fungitoxic Activity against and Phytotoxicity of Alkoxyclovanols and Alkoxyisocaryolanols.

Clovane and isocaryolane derivatives have been proven to show several levels of activity against the phytopathogenic fungus . Both classes of sesquiterpenes are reminiscent of biosynthetic intermediates of botrydial, a virulence factor of . Further development of both classes of antifungal agent requires exploration of the structure-activity relationships for the antifungal effects on and phytotoxic effects on a model crop. In this paper, we report on the preparation of a series of alkoxy-clovane and -isocaryolane derivatives, some of them described here for the first time (, , -, and -); the evaluation of their antifungal properties against , and their phytotoxic activites on the germination of seeds and the growth of radicles and shoots of (lettuce). Both classes of compound show a correlation of antifungal activity with the nature of side chains, with the best activity against for , , and . In general terms, while 2-alkoxyclovan-9-ols (-) exert a general phytotoxic effect, this is not the case for 2-arylalkoxyclovan-9-ols (-) and 8-alkoxyisocaryolan-9-ols (-), where stimulating effects would make them suitable candidates for application to plants.