Novel benzo-1,2,3-thiadiazole-7-carboxylate derivatives as plant activators and the development of their agricultural applications.

Plant activators are a novel kind of agrochemicals that could induce resistance in many plants against a broad spectrum of diseases. To date, only few plant activators have been commercialized. In order to develop novel plant activators, a series of benzo-1,2,3-thiadiazole-7-carboxylate derivatives were synthesized, and the structures were characterized by (1)H NMR, IR, elemental analyses, and HRMS or MS. Their potential systemic acquired resistance as plant activators was evaluated as well. Most of them showed good activity, especially, fluoro-containing compounds 3d and 3e, which displayed excellent SAR-inducing activity against cucumber Erysiphe cichoracearum and Colletotrichum lagenarium in assay screening. Field test results illustrated that compounds 3d and 3e were more potent than the commercial plant activator, S-methyl benzo[1,2,3]thiadiazole-7-carbothioate (BTH) toward these pathogens. Further, the preparation of compound 3d is more facile than BTH with lower cost, which will be helpful for further applications in agricultural plant protection.