Optimization of the synthetic route and insecticidal activity of a new insecticide spidoxamat

To optimize the synthetic route and explore its application prospects of spidoxamat in the field of agricultural pest control in China, spidoxamat was synthesized using two synthetic routes, in three steps starting from aniline and 4,4-dimethyl-4,5-dihydrooxazole, with yield of 40% and 12% respectively. The structure of spidoxamat was confirmed by ¹H NMR and HRMS. The insecticidal activities of spidoxamat against Aphis craccivora, Aphis gossypii, Bemisia tabaci, Psylla chinesis, Tetranychus cinnabarinus, Tetranychus urticae, Eriococcus lagerstroemiae, Nilaparvata lugens and Meloidogyne incognita were tested indoors. Bioassay results revealed that at 10.0 mg/L, the mortality of spidoxamat against both nymphs of A. craccivora and A. gossypii reached 100%; At 1.0 mg/L, the activity of spidoxamat against A. craccivora is comparable to that of imidacloprid (mortality is 96.67% and 100.00%, respectively); The LC₅₀ values of spidoxamat and imidacloprid against young A. craccivora were 0.0443 mg/L and 0.0881 mg/L, respectively, demonstrating that spirotetramat exhibited higher insecticidal activity than imidacloprid. At 100.0 mg/L the mortality against young P. chinesis reached 100%; against adult female T. cinnabarinus is over 90%, against adult B. tabaci is over 80%, and against T. urticae is over 70%. However, the insecticidal activities against young N. lugens, female adult E. legerstroemiae, and M. incongnita are moderate. At 10.0 mg/L, the activity of spidoxamat against P. chinesis is superior to that of avermectin (mortality is 90% and 70%). Both synthetic routes successfully yielded spidoxamat, which can provide a technical basis for further new structure derivatization. Spidoxamat exhibits excellent insecticidal activities against A. craccivora, A. gossypii, and P. chinesis, and has good application prospects in the field of agricultural pest control.