Rational design, synthesis and structure-activity relationship of novel substituted oxazole isoxazole carboxamides as herbicide safener

A series of novel substituted oxazole isoxazole carboxamides derivatives were designed on the basis of active subunit combination. Forty-four novel compounds were synthesized by an efficient one-pot procedure under microwave irradiation. The bioactivity was evaluated as herbicide safener against the injury of chlorsulfuron. It was found that most of the synthesized compounds displayed remarkable protection against chlorsulfuron via enhanced glutathione content and glutathione S transferase activity. Especially compound I-11 exhibited better bioactivity than the safeners isoxadifen-ethyl and R-28725. Molecular docking simulations suggested that the target compounds could compete with chlorsulfuron in the active site of acetolactate synthase, which could explain the protective effects of safeners. The present work demonstrates that the target compounds containing oxazole isoxazole groups could be considered as potential candidates for developing novel safeners in the future.