The Crocacins: Novel natural products as leads for agricultural fungicides

A short route to the synthesis of analogues of the antifungal but unstable natural product crocacin D was developed. A wide range of compounds were made in which the complex side chain was replaced by simple aromatic units, and many of them showed high activity in a mitochondrial beef heart respiration assay. Some of these compounds were active against plant pathogenic fungi of agricultural importance in glasshouse tests. In order to find compounds with greater stability than the natural crocacins, the photolabile (Z)-enamide was replaced with many different moieties, but none gave rise to useful fungicidal activity.