Study On Synthesis And Bioactivities Of Novel Uracil And Benzoxazine Derivatives

In the 21^th century, pesticide must have the characteristics of high effect, safety, low cost and environmentally-friend. Tetra-substituded benzene herbicides are Protoporphyriinogen oxidase (protox) inhibitors and light-dependent herbicides, which will be found a wider application because their unique herbicidal mechanism can ensure very good selectivity between human, animals and plants.To overcome limitations of some lead compounds in physical property and biological activity, some novel compounds with latent protox inhibiting activity were designed by choosing commercial protox inhibitor butafenacil, flumioxazin and other herbicides as lead compounds based on pesticide molecular design technologies, such as activity sub-structure connecting and bioisosteric replacement; 9 kinds 92 novel uracil and benzoxazine derivatives were prepared and purified, and these compounds could be divided into 8 series: N-phenyluracil-2-isoindolinedione, N-phenyluracil-3-phenyl(alkyl)ur-ea, N-phenyluracil-N-acet(propan)amide, N-phenyluracil-N-benz(alkyl)am-ide, oxopyrrolidine substituted benzoxazine, N-benzoxazine-2-isoindoline-dione acetamide, N-benzoxazinebenzamide and two iodine substituted flumioxazin. Their structures were confirmed by ¹H NMR, IR, mass spectroscopy and elemental analysis. The first introduction of phenox-ypropanamide and urea group into phenyluracil derivatives and that of 2-oxo-pyrrolidine group into benzoxazine derivatives expanded the chemical structural types of tetra-substituded benzene and protox inhibitors.The bioassays of preliminary herbicidal activity were carried out according to the standard operation procedure of pesticide bioassay, and the results showed that many compounds exhibited higher inhibiting protox activity. For example, two compound of N-phenyluracil-N-propanamide derivatives and two compound of N-phenyluracil-N-alkylamide derivatives had comparable herbicidal activity as butafenacil, four compounds of N-phenyluracil-1-alkyurea derivatives possessed more than 80% herbicidal efficiency at 75 g ai/ha in both pre- and post-emergence treatments against both dicotyledon weeds such as Abutilon theophrasti M, Chenopodiun album L, Amaranthus retroflexus L and monocotyledon weeds such as Digitaria sanguinalis L, Echinochloa crus-galli L, Setaria viridis L. The injury symptoms against weeds included leaf cupping, crinkling, bronzing and necrosis, typical of protox inhibitor herbicides.The crystal of N-(4-ethyl-7-fluoro-3-oxo-3,4-dihydro-2H-benzo[b][1 ,4]-oxazin-6-yl)-4-(methylsulfonyl)-2-nitrobenzamideand2-{4-[(E)-2,3-diiodoa-llyl]-7-fluoro-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl}-4,5,6,7-tetrah-ydro-2H-isoindole-1,3-dione was parsed. The results of ¹H NMR and X-ray crystallographic measurement showed the information of ring conformations and hydrogen bonds in the molecule, which offered a valuable information and fact evidence for the further design of bio-active compounds.A new synthesis method of B2055 was discovered, in which chloride iodine was used as iodide reagent and acetic acid as solvent, with 90.7% yield and 95% purity. The method showed more economical and industrialized value.Qualitative study on the relationship between chemical structure and herbicidal activity outlined their orderliness. The results could be used to guide the further research for the design of novel pesticide molecules and the modification of lead compounds.