Synthesis and biological activity of N-((5-alkylthio-1,3,4-oxadiazole)-2-ylmethyl) tralopyril

In order to find new compounds with pesticide activity, a series of N-((5-alkylthio-1,3,4-oxadiazole)-2-methyl) tralopyril were designed and synthesized from tralopyril by nucleophilic substitution, hydrazinolysis and cyclization. The structures of these derivatives were confirmed by ¹H NMR and HRMS. The test against 5 pathogenic fungi showed that most of the target compounds had certain fungicidal activity at the concentration of 0.20 mmol/L, and the inhibitory rate of compound 5h against Magnaporthe oryzae was 60.07%, which was better than that of the control agent fludioxonil (58.21%). The results of insecticidal and acaricidal activities showed that at the concentration of 0.20 mmol/L, some of the target compounds had certain insecticidal and acaricidal activities against Spodoptera litura and adult mite of Tetranychus cinnabarinus, while all were lower than the control agent chlorfenapyr (100%). The results of nematicidal activity showed that most of the compounds exhibited excellent nematicidal activity at the concentration of 0.20 mmol/L. The LC₅₀ values of compounds 5k, 5r and 5s against Caenorhabditis elegans were 0.0918, 0.0733, 0.0810 mmol/L respectively, which were better than the control agent fosthiazate (0.2798 mmol/L). The target compounds synthesized in this study have certain fungicidal, insecticidal, acaricidal and nematicidal activities, which can provide a reference for the design and synthesis of tralopyril derivatives.