Acetohydroxyacid synthase (AHAS) was one of important herbicidal targets. However, the issue of weed resistance to commercial AHAS inhibitors has become one of the largest obstacles for their application. Therefore, there is a high demand to design new anti-resistance AHAS inhibitors. Herein, based on the reported low resistance AHAS inhibitors, a series of pyrimidyl-salicylates with "double oxygen bridge" utilized the "conformation flexibility analysis" strategy were designed. All the

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... ed compounds were characterized by 1 H NMR, 13 C NMR and HRMS. The bioactivity results showed that most of the derivatives displayed good inhibitory activities against P197L mutant. Especially, 2-((4,6-dimethoxypyrimidin-2yl)oxy)-6-(2-fluoro-4-nitrophenoxy)-4-methylbenzoic acid (6l) was identified as the most potent anti-resistance AHAS inhibitor. In addition, some compounds showed good weed control for resistant Descurainia sophia (P197L AHAS). Most importantly, 2-((4,6-dimethoxypyrimidin-2-yl)oxy)-6-(2-fluorophenoxy)-4-methylbenzoic acid (6b) showed 80% herbicidal activities against sensitive and resistant Descurainia sophia at the dosage of 150 g ai/ha. These results indicated that this type of compounds worth of the further investigation.