Synthesis and fungicidal activity of a series of novel aryloxylepidines

A series of novel (hetero)aryloxylepidine derivatives was devised as hybrid structures of the phenoxyquinoline and phenethoxyquin(az)oline fungicides. Synthesis of these targets required the development of several new routes to derivatised 4‐hydroxymethylquinolines, and subsequent coupling with phenols or haloarenes. The aryloxylepidines generally showed moderate broad‐spectrum fungicidal activity across several diseases of cereals. Substitution of the quinoline ring with chlorine at the 7‐ and/or 5‐positions gave molecules with high levels of protectant activity against Erysiphe graminis f sp tritici (powdery mildew of wheat), but this did not improve the level of fungicidal activity against other diseases. In vitro activity against mitochondrial electron transport complex I (MET) derived from Ustilago maydis showed that 8‐fluorolepidine analogues were moderately active at this target site, while the more fungicidally active 7‐ and 5,7‐substituted compounds were inactive. This indicates that MET is not the primary target of these highly active powdery mildewicides. © 2001 Society of Chemical Industry