In order to find new compounds with high activity, 20 1,2,3-Benzotriazin-4-one thioether (sulfone) derivatives containing oxadiazole fragments were designed and synthesized. The structure of the compounds was confirmed by ¹H NMR, ¹³C NMR and high-resolution mass spectrometry (HRMS). Compound 7c had a good inhibitory effect on Sclerotinia sclerotiorum, with an EC₅₀ value of 3.84 mg/L, which was comparable to that of the control agent hymexazol (5.43 mg/L); 7c (1.81 mg/L) against Rhizoctonia solani was comparable to that of carbendazim (1.09 mg/L), and significantly higher than that of the control agent hymexazol (45.70 mg/L). At the concentrations of 100 and 200 mg/L, the protective and curative effects of compound 7c against Rhizoctonia solani was 78.51% and 84.48%, and the curative effects was 60.34% and 78.91%, respectively, At low concentrations, the curative effects was comparable to that of carbendazim (61.53%). At a concentration of 100 mg/L, some compounds had certain in vitro activities against Caenorhabditis elegans and Bursaphelenchus xylophilus, and the LC₅₀ value of compound 6a against the J2 of C. elegans was 3.96 mg/L, which was better than that of Fosthiazate (57.39 mg/L) and comparable to that of fluopyram (4.68 mg/L). However, the virulence of compound 6a (50.28 mg/L) against B. xylophilus was lower than that of fosthiazate(24.68 mg/L) and fluopyram (0.57 mg/L). The target compounds synthesized in this study have high fungicidal activity and certain nematicidal activity, which can provide a reference for the study of new 1,2,3- benzotriazine-4-one derivatives.

Key words: 1,2,3-Benzotriazin-4-one, oxadiazole, thioether, sulfone, fungicidal activity, nematocidal activity