Discovery of ortho-Alkoxy Substituted Novel Sulfonylurea Compounds That Display Strong Herbicidal Activity against Monocotyledon Grasses

In the present study, we have designed and synthesized a series of 42 novel sulfonylurea compounds with ortho-alkoxy substitutions at the phenyl ring and evaluated their herbicidal activities. Some target compounds showed excellent herbicidal activity against monocotyledon weed species. When applied at 7.5 g ha(-1), 6-11 exhibited more potent herbicidal activity against barnyard grass (Echinochloa crus-galli) and crab grass (Digitaria sanguinalis) than commercial acetohydroxyacid synthase (AHAS; EC 2.2.1.6) inhibitors triasulfuron, penoxsulam, and nicosulfuron at both pre-emergence and postemergence conditions. 6-11 was safe for peanut for postemergence application at this ultralow dosage, suggesting that it could be considered a potential herbicide candidate for peanut fields. Although 6-11 and triasulfuron share similar chemical structures and have close K-i values for plant AHAS, a significant difference has been observed between their LUMO maps from DFT calculations, which might be a possible factor that leads to their different behaviors toward monocotyledon weed species.

Automated summary

A series of 42 novel sulfonylurea compounds were synthesized and evaluated for their herbicidal activities against monocotyledon weed species, showing potential for safe and effective use in peanut fields at ultralow dosages. The chemical structure and electronic properties were found to influence the compounds' behavior towards different plant species.