在这项研究中,我们研究了双吡喃酚酯的特性和除草潜力,属于乙酰羟酸合酶(AHAS-)抑制除草剂的2-(嘧啶-2-基氧基)苯甲酸(PYB)类。这些除草剂主要用于防治禾本科和阔叶杂草。其中,bispyribac钠在该类中脱颖而出。令人惊讶的是,其他bispyribac酯,与bispyribac-钠相比,包括链烷醇和酚酯的除草活性大大降低。相比之下,肟酯(例如,吡啶苯并辛)表现出高活性。为了进一步了解和开发新的PYB除草剂,我们合成并筛选了一系列双吡喃酚酯,同时研究了它们的光化学行为。几种化合物表现出优异的除草活性,化合物Ia-19和Ic显示出令人印象深刻的90%有效剂量,用于抑制barnyard草的鲜重,分别为0.55和0.60ga.i./hm2。这些值大约是二吡唑钠或吡啶并氧肟的一半。结果表明,酚酯的除草活性受它们与AHAS酶的结合能力以及它们分解成双吡喃酸的影响。例如,与bispyribac-钠相比,bispyribac苯酚酯表现出大大降低的受体亲和力,在转化为双吡喃酸方面面临挑战,解释其减少的除草活性。然而,引入一个光敏硝基基团导致一个完整的转变。这种修饰改善了其与AHAS的亲和力,并加速了其分解为双吡喃酸,通过光催化进一步加速。因此,含硝基化合物显示出增强的除草活性。这项研究的结果通过定量结构-活性关系分析为酚酯的结构优化开辟了可能性,潜在地调节他们的活动释放期。此外,芳香杂环酯的高活性为开发新型PYB除草剂提供了新的见解。
In this study, we investigated the characteristics and herbicidal potential of bispyribac phenolic esters, which belong to the 2-(pyrimidin-2-yloxy)benzoic acid (PYB) class of acetohydroxyacid synthase (AHAS-)-inhibiting herbicides. These herbicides are primarily used for controlling Poaceae and broadleaf weeds. Among them, bispyribac-sodium stands out as a representative in this class. Surprisingly, other bispyribac esters, including alkanol and phenol esters exhibit considerably reduced herbicidal activity compared to bispyribac-sodium. In contrast, oxime esters (e.g., pyribenzoxim) demonstrate high activity. To further understand and develop novel PYB herbicides, we synthesized and screened a series of bispyribac phenolic esters while investigating their photochemical behaviors. Several compounds displayed excellent herbicidal activity, with compounds Ia-19 and Ic showing impressive 90% effective dosages for fresh weight inhibition of barnyard grass, measuring 0.55 and 0.60 g a.i./hm2, respectively. These values were approximately half of bispyribac-sodium or pyribenzoxim. The results indicate that the herbicidal activity of phenolic esters is influenced by both their binding ability to the AHAS enzyme and their decomposition into bispyribac acid. For instance, bispyribac phenol ester exhibited considerably reduced receptor affinity compared to bispyribac-sodium, and faced challenges in transforming into bispyribac acid, explaining its diminished herbicidal activity. However, introducing a photosensitive nitro group led to a complete transformation. This modification improved its affinity with AHAS and accelerated its decomposition into bispyribac acid, further accelerated by photocatalysis. Consequently, nitro-containing compounds displayed heightened herbicidal activity. The findings from this study open possibilities for structural optimization of phenolic esters through quantitative structure-activity relationship analysis, potentially regulating their activity-releasing period. Furthermore, the high activity of aromatic heterocyclic esters offers new insights into developing novel PYB herbicides.