Synthesis And Herbicidal Activity Of Novel 4, 6-dimethoxypyrimidine Derivatives

As a kind of inhibitors of Acetolactate Synthase, Pyrimidylsalicylate is highly effective, safe herbicide which also easily well going with environment. This kind of herbicides has a very bright future because of its unique action mechanism which did a great contribution to the high selectivity between animals and plants. Since the 90s of the last century, the research and exploration of this kind of compounds achieved great success. A series of commercial herbicides were found or explored, such as bispyribac-sodium (KIH-2023), pyribenzoxim (LGC-40863) and Pyriftalid (CGA-279233), etc. However, as we all know that the resistance appeared after the long term use of herbicides, new frame construction are needed to be found to keep or improve the biological activity.To investigate the highly effective frame construction or initial structure, based on the structures of the commercial herbicides such as Pyriminobac-methyl, patent compound ZJ0777 and N-(2-((4,6Klimemoxypyrimidin-2-yl)(hydroxy)methyl)phenyl)-1,1,1-trifluoromethanesulfonamide, 148 novel pyrimidine derivatives and 5 known compounds of seven series were designed and synthesized with the theory of bioisosteric replacement and the principle combination of active groups, which improved the disadvantages of physics and bioactivity. ~1H NMR, MS, spectrum, elemental analysis, X-ray diffraction analysis, and other related tools were used to characterize the structure of all synthesized compounds. The structures of the seven series compounds are shown as follows:Bioactivities of all compounds in postemergence treatments were performed at the concentration of 150 g/hm~2 using Echinochloa crusgalli, Digiatra sanguinalis, Setaria viridis, Annual bluegrass, Brassica juncea, Amaranthus retroflexus and Chenopodium album as inhibition target. Then, in the two series of IV and V, many compounds showed very good herbicides activity, such as Y6775, Y6776, Y6777, Y6778, Y6795, Y67CN2 and Y67CN7, which also were highly effective (inhibition ratio is higher than 80%) and had broad spectrum. Especially the compound Y6795 showed good inhibition (more than 80%) toward Setaria viridis, Chenopodium album and Amaranthus retroflexus with further screening experiment at a low using concentration of 37.5 g/hm~2. Meanwhile, it is safe to rape after the safety evaluation and more details would be found in furture. Right now, the evaluation of the safety of Y67CN2 and Y67CN7 toward plants are being studying. Series of I and II, none special bioactivity was found of the frame construction and its related structures. So we hope this will be improved with further modification of the frame construction. The herbicides activity test of series III, VI and VII are progressing. More, via the enzymatic assay (AHAS) of the IV type compounds, some of these compounds exhibited high enzyme inhibitory activity, and the symptoms like the plant leaf cupping, crinkling, bronzing and necrosis were found during the against weeds test which was the typical symptoms of AHAS inhibitor.