文摘
A series of 2-substituted-8-(4,6-dimethoxypyrimidin-2-yloxy)-4-methylphthalazin-1-one derivatives, 7a-7w, were designed via an ortho-substituent cyclization strategy to discover a new herbicidal leadstructure. These compounds were synthesized by a seven-step route using 3-hydroxy-acetophenoneas a starting material. Determination of the Ki values against wild-type A. thaliana acetohydroxyacidsynthase (AHAS) (EC 4.1.3.18) indicated that some of the compounds displayed good enzymeinhibition activity comparable to that of KIH-6127. The further preliminary bioassay data on weedsshowed that the synthesized compounds exhibited typical injury symptoms of AHAS-inhibitingherbicides, and some of them showed broad-spectrum and high herbicidal activities in postemergencetreatments against Echinochloa crusgalli, Digitaria sanguinalis, Setaria viridis, Brassica juncea,Amaranthus retroflexus, and Chenopodium album at an application rate of 150 g ai/ha. To ourknowledge, this is the first report of methylphthalazin-1-one derivatives as AHAS inhibitors.