Novel plant activators with thieno[2,3-d]-1,2,3-thiadiazole-6-carboxylate scaffold: Synthesis and bioactivity

The 1,2,3-thiadiazole-carboxylate moiety was reported to be an important pharmacophore of plant activators. In this study, a series of novel plant activators based on thieno[2,3-d]-1,2,3-thiadiazole-6-carboxylate were designed and synthesized and their biological activity as plant activators was studied. The structures of the novel compounds were identified by ¹H NMR, ¹⁹F NMR and HRMS. The in vivo bioassay showed that these novel compounds had good efficacy against seven plant diseases. Especially, compounds 1a and 1c were more potent than the commercialized plant activator BTH. Almost no fungicidal activity was observed for the active compounds in the in vitro assay, which matched the requirements as plant activators.