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.