Molecular design,synthesis and biological activities of amidines as new ketol-acid reductoisomerase inhibitors

Diamidine （A） was identified in our in vitro bio-assay as a possible inhibitor of ketol-acid reductoisomerase （KARI） from the ACD database search based on the known three-dimensional crystal structure of KARI. An investigation on interaction of A on KARI active sites, led to the design and synthesis of 15 novel monoamidines. Some of those showed better biological activity than A on rice KARI （in vitro） and in greenhouse herbicidal tests （in vivo）. The structure-biological activity relationship was investigated, which provides valuable information to further study of potential KARI inhibitors.

Syntheses,Crystal Structures and Bioactivities of Two Isatin Derivatives

The title compounds（Z）-3-（2-（3-chloropyridin-2-yl）hydrazono）indolin-2-one（A） and 7-bromo-（Z）-3-（（4-pyridinyl）carboxlichydrazono）-2-indolinone（B） have been synthesized and structurally determined by elemental analysis and single-crystal X-ray diffraction studies.Compound A（C13H8ClN4O） belongs to the orthorhombic crystal system,space group Pca21 with a = 20.799（4）,b = 4.9312（10）,c = 11.764（2）,V = 1206.6（4）3,Mr = 271.68,Dc = 1.496 g/cm3,μ = 0.313 mm-1,F（000） = 556,Z = 4,the final R = 0.0346 and wR = 0.0831 for 2683 observed reflections with I 2σ（I）.Compound B（C14H9BrN4O2） belongs to the triclinic crystal system,space group P1 with a = 6.6834（13）,b = 7.0727（14）,c = 14.285（3）,α = 95.56（3）,β = 99.00（3）,γ = 102.95（3）°,V = 643.8（2）3,Mr = 345.16,Dc = 1.780 g/cm3,μ = 3.203 mm-1,F（000） = 344,Z = 2,the final R = 0.0487 and wR = 0.1167 for 2334 observed reflections with I 2σ（I）.The preliminary herbicidal bioassay reveals that compounds A and B have some inhibition both in vivo and in vitro against AHAS.

Syntheses and Biological Activities of Ethyl N-Hydroxy-N-(substituted)phenyloxamates as KARI Inhibitors

Nine ethyl N-hydroxy-N-（substituted） phenyloxamates （2a-2i）, based on the structure of the KARI inhibitor IpOHA, were synthesized. Their structures were established on the bases of 1^H NMR, IR, ESI-MS and elemental analyses. Among the nine compounds, four show in vitro inhibitory activity on rice KARI, with 2c and 2g[ Ki values of （35.2±4.9） and （49.4 ±6. 3） μmol/L] having similar activity to the precursor of IpOHA（A, Ki =34. 1±6. 7 μmol/L）. The results will be helpful to further molecular design of more potent KARI inhibitors.

Synthesis, Dimeric Crystal Structure, and Biological Activities of N-(4-Methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl)-N′-(2-trifluoromethyl-phenyl)-guanidine

The title compound, N-（4-methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl）-N＇-（2-tritluoromethyl-phenyl）-guanidine, was synthesized and its structure was confirmed by using IR, MS,^1H NMR, and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound has a weak herbicidal activity.

Design, Synthesis and Biological Activity of Substituted-N-[4-(substituted-phenylsulfamoyl)phenyl]benzamide as Potential AHAS Inhibitors

Based on the crystal structure of AHAS/sulfonylurea complex, we obtained 296 compounds with low binding energy towards AHAS via virtual screening. One series of them have been synthesized. Preliminary bioassay indicated that some compounds displayed good herbicidal activity on rape and bamygrass and inhibited AHAS to some extent. This study indicated the rationality of our molecular design based on the crystal structure of target enzyme.

Synthesis and Insecticidal Activity of Novel N-Pyridylpyrazole Carbonyl Thioureas

A series of novel N-pyridylpyrazole carbonyl thioureas were designed and synthesized. Their structures were characterized by melting points, 1H NMR, IR and elemental analysis or HRMS. The bioassay tests indicated that some of these compounds exhibited moderate insecticidal activity against Mythirnna separata Walker and Culex pipiens pallens. Among 17 compounds, 5n and 5p showed 100% larvicidal activity against Mythimna separata Walker at the test concentration of 100 mg/L.

Synthesis and Biological Activity of Novel Furan/Thiophene and Piperazine-Containing （Bis）1,2,4-triazole Mannich Bases

A series of novel furan/thiophene and piperazine-containing 1,2,4-triazole Mannich bases and bis（1,2,4-triazole） Mannich bases have been conveniently synthesized via Mannich reaction with triazole Schiff bases, various pipera- zinc derivatives, and formaldehyde as intermediates in good yields. Their structures were characterized by melting points, ~H NMR, 13C NMR, IR and elemental analysis. The preliminary bioassay showed that most compounds ex- hibited significant in vitro and in vivo fungicidal activity against several test plant fungi. Among 32 new compounds, the trifluoromethyl-containing compounds showed superior activity than the methyl-containing ones. Several com- pounds, such as FS, F9, F10, G5, HT, 118, 13 and 14, were comparable with some commercial fungicides against different fungi during the present study and could be further structurally optimized. Meanwhile, several compounds showed good herbicidal activity against Brassica campestris at 100 ~tg/mL and KARl inhibitory activity at 200 μg/mL. However, compounds exhibited poor insecticidal activity against oriental armyworm at 200 μg/mL in the preliminary studies. The research results will provide useful information for the design and discovery of new agro- chemicals with novel heterocyclic structures.

Synthesis and in vitro Fungicidal Activity of a Series of Novel N-（Heterocycly）phthalimides

A series of novel phthalimides was prepared and tested for antifungal activity in vitro against seven phytopa- thogenic fungi： Rhizoctonia solani, Fusarium oxysporum f.sp. cucumerinum Owen., Botrytis cinerea, Fulvia fulva, Sclerotinia sclerotiorum de Bary, Phytophthora capsici, Botryosphaeria berengeriama. The results showed that those compounds holding the structure of 6-methylpyridin-2-yl exhibited good activity against Phytophthora capsici and Botrytis cinerea.