Design, Synthesis, and Bioevaluation of Substituted Phenyl Isoxazole Analogues as Herbicide Safeners.

Herbicide safeners enhance herbicide detoxification in crops without affecting target weed sensitivity. To enhance crop tolerance to the toxicity-related stress caused by the herbicide acetochlor (ACT), a new class of substituted phenyl isoxazole derivatives was designed by an intermediate derivatization method as herbicide safeners. Microwave-assisted synthesis was used to prepare the phenyl isoxazole analogues, and all of the structures were confirmed via IR, H NMR, C NMR, and HRMS. Compound was further characterized by X-ray diffraction analysis. Bioassay results showed that most of the obtained compounds provided varying degrees of safening against ACT-induced injury by increasing the corn growth recovery, glutathione content, and glutathione -transferase activity. In particular, compound showed excellent safener activity against ACT toxicity, comparable to that of the commercial safener benoxacor. Gaussian calculations have been performed and the results indicated that the nucleophilic ability of compound is higher than that of benoxacor, thus the activity is higher than that of benoxacor. These findings demonstrate that phenyl isoxazole derivatives possess great potential for protective management in cornfields.