As important chemical pesticides, protoporphyrinogen oxidase (PPO, EC 1.3.3.4) herbicides play a vital role in weed management. Herein, in a search for novel PPO herbicides, a series of phenoxypyridine-2-pyrrolidinone derivatives were synthesized and their herbicidal activities were tested. To confirm the structures of the newly synthesized compounds, a colorless single crystal of compound 9d was obtained and crystallographic data collected. PPO inhibition experiments showed that most compounds have PPO inhibitory effects. The half-maximal inhibitory concentration (IC50) of compound 9d and oxyfluorfen were 0.041 mg/L and 0.043 mg/L, respectively, which showed compound 9d was the most potent compound. Compound 9d reduced the Chlorophyll a (Chl a) and Chlorophyll b (Chl b) contents of Abutilon theophrasti (A. theophrasti), to 0.306 and 0.217 mg/g, respectively. Crop selectivity experiments and field trial indicated that compound 9d can potentially be used to develop post-emergence herbicides for weed control in rice, cotton, and peanut. Molecular docking studies showed that both oxyfluorfen and compound 9d can enter the PPO cavity to occupy the active site and compete with the porphyrin to block the chlorophyll synthesis process, affect photosynthesis, and eventually cause weed death. Compound 9d was found to be a promising lead compound for novel herbicide development.

中文翻译：

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新型苯氧基-（三氟甲基）吡啶-2-吡咯烷酮基原卟啉原氧化酶抑制剂：设计、合成和除草活性

作为重要的化学农药，原卟啉原氧化酶（PPO，EC 1.3.3.4）除草剂在杂草治理中起着至关重要的作用。在此，为了寻找新型 PPO 除草剂，合成了一系列苯氧基吡啶-2-吡咯烷酮衍生物并测试了它们的除草活性。为了确认新合成化合物的结构，获得了化合物 9d 的无色单晶并收集了晶体学数据。PPO抑制实验表明，大多数化合物具有PPO抑制作用。化合物9d和氧氟草醚的半数抑制浓度(IC50)分别为0.041 mg/L和0.043 mg/L，表明化合物9d是最有效的化合物。化合物 9d 将 Abutilon theophrasti (A. theophrasti) 的叶绿素 a (Chl a) 和叶绿素 b (Chl b) 含量降低至 0.306 和 0.217 mg/g，分别。作物选择性实验和田间试验表明，化合物 9d 可用于开发水稻、棉花和花生杂草控制的芽后除草剂。分子对接研究表明，氧氟草醚和化合物9d均可进入PPO空腔占据活性位点，与卟啉竞争阻断叶绿素合成过程，影响光合作用，最终导致杂草死亡。发现化合物 9d 是开发新型除草剂的有前途的先导化合物。分子对接研究表明，氧氟草醚和化合物9d均可进入PPO空腔占据活性位点，与卟啉竞争阻断叶绿素合成过程，影响光合作用，最终导致杂草死亡。发现化合物 9d 是开发新型除草剂的有前途的先导化合物。分子对接研究表明，氧氟草醚和化合物9d均可进入PPO空腔占据活性位点，与卟啉竞争阻断叶绿素合成过程，影响光合作用，最终导致杂草死亡。发现化合物 9d 是开发新型除草剂的有前途的先导化合物。