Synthesis And Herbicidical Activity Of Uracil Derivatives

"High-efficiency, low toxicity, safety" has already become the theme of discovering new pesticide. Protoporphyrinogen oxidase (protox) inhibitors make action on chlorophyll of plant cell, which ensure the toxic selectivity between animal and plant. They have the characteristic of high efficiency, short residual time, high selectivity, safety to non-target creature and friendly to environment. Uracil derivatives not only have been used widespread in medicine, but also are very important agrochemicals. Many of them have been developed to be herbicide, for example, benzfendizone and butafenacil have commercialized in recent years.The latest research and development of herbicide and protox inhibitors were reviewed in this article. The current research progress, action mechanism and structure activity relationship of protox inhibitors were introduced in detail. We also present the latest progress on 3-aryl uracil derivatives, including their structures, research process, synthetic methods, bioactivities, along with prospects and trends for future development of uracil derivatives.On basis of the structures of leading compounds of protox inhibitors and their unique action mechanism, 39 new compounds were synthesised by me too designing priniciples such as sub-structure linkage and bioisosterism. Their structures were confirmed by IR, ¹H NMR and LC/MS.According to their structures, these compounds can be divided into four series as following:(1)N-(2,4-disubstituted-5-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-2,3-dihydropyrim idin-1(6i/)-yl)phenyl) amidesâ… :â… X = H, FR = 2-CIC₆H₄, 3-ClC₆H₄, 4-BrC₆H₄, 2,4-diFC₆H₃,4-NO₂C₆H₄, C₆h₅ch₂, 2-CH₃C₆H₄, 4-CH₃OC₆H₄, CLCH₂CH₂ , ClCH₂C(CH₃)₂CH₂ (2)N-(2,4-disubstituted-5-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-2,3-dihydropyrim idin-1(6H)-yl)phenyl)-N-substituted-2-substituted benzoxyacetamides (benzoxypropan- amides)â…¡:X = H, F; R¹=H, CH₃; R²=H, CH₃, 3-FC₆H₄O Y=3-F, 3-Cl, 2-CH₃, 3-CH₃, 4-CH₃, 3,5-diCH₃, 3-CH₃-4-Cl, 4-COOCH₃(3)N-(2,4-disubstituted-5-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-2,3-dihydropyrim idin-1(6H)-yl)phenyl)imidesâ…¢:X=H,FZ=H, 4-CH₃, 4-NO₂, 4,5-diCl(4)N-(2,4-disubstituted-5-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-2,3-dihydropyrim idin-1(6H)-yl)phenyl)-N', N'-disubstituted urea derivativesâ…£:X=H,FR₄=R₅=-CH₂CH₂CH₃, -CH(CH₃)₂, -CH₂CH₂CH₂CH₃ R₄=Hæ—¶R₅=4-CF₃OC₆H₄, 2-FC₆H₄ Compoundsâ… ,â…¢and some of compoundsâ…¡were tested for herbicidal activity. It was found that these compounds showed different herbicidal activity by post-emergence treatment and pre-emergence treatment. The herbicidal activity on dicotyledon weeds is better than on monocotyledon weeds. Some of the compounds exhibited 100% inhibition to dicotyledon weeds at 75g a.i./hm², such as Abutilon theophrasti, Amaranthus spinosus by post-emergence treatment. During the further research, some compounds exhibited 90% inhibition to Abutilon theophrasti, Amaranthus spinosus at lower dosage. The bioassay of compoundsâ…£is underway.