Synthesis and Pesticidal Activities of New Quinoxalines

Abstract

Natural products are a source of many novel compounds with biological activity for the discovery of new pesticides and pharmaceuticals. Quinoxaline is a fused <i>N</i>-heterocycle in many natural products and synthetic compounds, and seven novel quinoxaline derivatives were designed and synthesized <i>via</i> three steps. Pesticidal activities of title quinoxaline derivatives were bioassayed. Most of these compounds had herbicidal, fungicidal, and insecticidal activities. The compounds 2-(6-methoxy-2-oxo-3-phenylquinoxalin-1(2<i>H</i>)-yl)acetonitrile (<b>3f</b>) and 1-allyl-6-methoxy-3-phenylquinoxalin-2(1<i>H</i>)-one (<b>3g</b>) were the most active herbicides and fungicides. Mode-of-action studies indicated that <b>3f</b> is a protoprophyrinogen oxidase-inhibiting herbicide. Compound <b>3f</b> also possessed broad-spectrum fungicidal activity against the plant pathogen <i>Colletotrichum</i> species. Some of these compounds also had insecticidal activity. Molecular docking and DFT analysis can potentially be used to design more active compounds.