Structural design and insecticidal activity of 1,3,4-oxadiazole-ring containing pyridylpyrazole-4-carboxamides

The insecticidal activity of 1,3,4-oxadiazole-ring containing pyridylpyrazole-4-carboxamides against diamondback (Plutella xylostella) and noctuid (Spodoptera frugiperda) moths were evaluated. Only substitutions on the 1,3,4-oxadiazole moiety dictated bioreactivity, with 8q2 m-CF₃Ph being the most effective against Plutella xylostella, showing 80%–93% mortality at a concentration of 0.5–500 μg ml⁻¹ while the others remained inactive or less active (highest mortality being 63%). The larvicidal activity against Spodoptera frugiperda was inferior compared with that of Plutella xylostella, with the highest mortality being 33%. A crystal of 8q5 was obtained and analyzed, revealing the effects of intramolecular H-bonds and intermolecular π-π interactions.