Novel 1,3,4-oxadiazole thioether derivatives containing flexible-chain moiety: Design, synthesis, nematocidal activities, and pesticide-likeness analysis

Seventy-two novel 1,3,4-oxadiazole thioether derivatives containing different flexible-chain moieties were designed and synthesized. The nematicidal activities of all the title compounds were evaluated, and some compounds showed excellent nematicidal activities against citrus nematodes. The compounds 15, 16, 18, 27, 41, 42, 44, 53, and 71 had the mortality to citrus nematodes of 92.5, 93.7, 90.3, 91.5, 92.6, 92.8, 93.5, 91.3, and 91.0% at the concentration of 100 mg/L, which were better than the control agent of avermectin (85.9%). After the test concentration was reduced to 50 mg/L, the nematicidal activities of the compounds 16, 42, 44, 53, and 71 were still superior to avermectin (65.1%), with the mortality of 72.3, 71.3, 70.6, 71.1, and 73.9%, respectively. The LC50, values of the compounds 16, 42, 44, 53, and 71 were 16.3, 18.8, 20.8, 17.5, and 14.7 mg/L, which were better than the commercial positive control agent of avermectin (24.8 mg/L). Meanwhile, the qualitative and quantitative analysis of the pesticide-likeness shows that compound 71 exhibits the potential insecticide-likeness. This work indicates that novel 1,3,4-oxadiazole thioether derivatives containing flexible-chains deserve further research as potential nematicides to protect citrus crops in the future.