Xiaomao Zou

Synthesis and insecticidal activities of novel pyrazole oxime ether derivatives with different substituted pyridyl rings

BACKGROUND Pyrazole oxime ether derivatives with different substituted pyridyl rings represent new types of compounds that possess good insecticidal and acarcidal activity against Aphis laburni Kaltenbach and Tetranychus cinnabarinus. RESULTS In total, 82 novel pyrazole oxime ether derivatives were synthesized and identified by (1) H NMR, elemental analysis or high-resolution mass spectrometry, and their insecticidal and acarcidal activities were tested against A. laburni Kaltenbach and T. cinnabarinus. Bioassays showed that at a 200 mg L(-1) dosage, one-third of the compounds displayed high insecticidal activity against A. laburni Kaltenbach (> 90%), whereas most of of the compound II series exhibited excellent acarcidal activity against T. cinnabarinus (> 92%). Most compound II series exhibited good activity in both insecticidal and acarcidal tests. In addition, at a low concentration of 10 mg L(-1) , the insecticidal activity of compounds IB9 and IE4 exceeded 90%, and the acarcidal activity of compounds IIB1 and IIB2 was ≥ 95%. CONCLUSION Structure-activity relationships were also examined. Results suggested that the tert-butoxycarbonyl group, as well as the position between tert-butoxycarbonyl and the atom N of the pyridyl ring, were essential to obtaining the acarcidal activity of the title compounds.

Novel protoporphyrinogen oxidase inhibitors: 3H-pyrazolo[3,4-d][1,2,3]triazin-4-one derivatives.

A series of 3 H-pyrazolo[3,4-d][1,2,3]triazin-4-one derivatives were synthesized as candidate herbicides by diazotization of different 5(3)-amino- N-phenyl-1 H-pyrazole-4-carboxamide derivatives prepared by the reaction of substituted 5(3)-amino-pyrazole-4-carbonyl chloride with a substituted aniline. Their structures were identified by (1)H NMR and elemental analyses. The isomers D and E were isolated, and their structures were identified by two-dimensional NMR analyses (heteronuclear single quantum coherence and heteronuclear multiple-bond correlation) and single-crystal X-ray diffraction analysis. The bioassay results showed that some of the title compounds exhibited both excellent herbicidal activity at a dose of 93.75 g/ha and strong inhibition against protoporphyrinogen oxidase activity in vitro. The structure-activity relationship showed that D16 possessed the highest activities both in vivo and in vitro when the N-substituted group of the pyrazole ring was allyl and the N-substituted group of benzooxazinone was propargyl.

Synthesis and herbicidal activities of novel 3-N-substituted amino-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives.

4-(3-Trifluoromethylphenyl)pyridazine is a new series of compounds with bleaching and herbicidal activities. Starting from ethyl 2-(3-trifluoromethylphenyl)acetate, an important intermediate 7 was synthesized in five steps with a moderate total yield of 51.5% in a safe and practical way. Twenty-six novel 3-N-substituted amino-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives were synthesized and evaluated through a Spirodela polyrrhiza test and greenhouse test. Some compounds can completely inhibit Chl at 1 microg/mL and exhibit equal or higher herbicidal activities with the commercial bleaching herbicide diflufenican against dicotyledonous plants at a rate of 75 g/ha.

The Synthesis and Herbicidal Activity of 1-Alkyl-3-(α-hydroxysubstituted benzylidene)pyrrolidine-2,4-diones

In the search for better herbicides a series of 1-alkyl-3-(α-hydroxy-(un)substituted benzylidene)pyrrolidine-2,4-diones were prepared and their structure-activity relationships studied. All their structures have been confirmed by 1H-NMR and elemental analysis. The preliminary bioassay results indicated that some of them have high herbicidal activity against annual dicotyledonous and monocotyledonous plants.

Synthesis and herbicidal activities of novel 3-(substituted benzyloxy or phenoxy)-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives.

BACKGROUND 4-(3-Trifluoromethylphenyl)pyridazine represents a new series of compounds with bleaching and herbicidal activities. RESULTS A total of 43 novel 3-(substituted benzyloxy or phenoxy)-6-methyl-4-(3-trifluoromethylphenyl)pyridazine derivatives were synthesised, and their bleaching and herbicidal activities were evaluated through Spirodela polyrrhiza and greenhouse tests. Some compounds exhibited excellent herbicidal activities, even at a dose of 7.5 g ha(-1). CONCLUSION The results showed that a substituted phenoxy group at the 3-position of the pyridazine ring and the electron-withdrawing group at the para-position on the benzene ring were essential for high herbicidal activity.

1-Benzyl-3-(α-hydroxy­benzyl­idene)­pyrrolidine-2,4-dione

The title compound, C18H15NO3, is a potent new herbicide containing the pyrrolidine-2,4-dione ring system. In the crystalline state, the molecular skeleton contains one enol hydrogen-bonded moiety, formed from benzoyl Czdbnd;O isomerization.

3-(α-Hydro­xy-2-methoxy­lbenzyl­idene)-1-iso­propyl­pyrrolidine-2,4-dione

The title compound, C15H17NO4, is a potent new herbicide containing the pyrrolidine-2,4-dione ring system. In the crystalline state, the molecular skeleton contains one enol grouping, which is intramolecularly hydrogen bonded to a neighboring keto O atom.

tert-Butyl 4-({[(E)-1,3-dimethyl-5-phen-oxy-pyrazol-4-yl]meth-yl}amino-oxymeth-yl)benzoate.

The title compound, C24H27N3O4, also known as fenpyroximate, is a commercial acaricide. The benzene ring of the phenoxy group is approximately perpendicular to the pyrazole ring with a dihedral angle of 84.37 (11)°. The dihedral angle between the phenoxy and the benzoate benzene rings is 48.83 (8)°.

4-[3-(Trifluoro-meth-yl)phen-yl]-5,6,7,8-tetra-hydro-cinnolin-3(2H)-one.

The title compound, C15H13F3N2O, contains one benzene ring, one cyclohexane ring and a pyridazine ring. The dihedral angle formed by the pyridazine ring with the benzene ring is 61.5 (2)°. The crystal structure is stabilized by two intermolecular hydrogen bonds (N—H⋯O and C—H⋯F). The cyclohexane ring adopts a screw-boat conformation. The CF3 group is disordered over two positions; the site occupancy factors are ca 0.6 and 0.4.

Methyl 3-(4-{6-methyl-4-[3-(trifluoro­meth­yl)phen­yl]pyridazin-3-yl­oxy}phen­yl)propanoate

In the title compound, C22H19F3N2O3, the benzene rings of the trifluoromethylphenyl and benzoylphenyl groups form dihedral angles of 41.89 (10) and 67.44 (10)°, respectively, with the pyridazine ring. The methylpropanoate group is nearly coplanar with the attached benzene ring [dihedral angle = 3.9 (2)°]. The trifluoromethyl group is disordered over two positions; the site-occupancy factors are ca 0.64 and 0.36. In the crystal structure, inversion-related molecules are linked through C—H⋯O hydrogen bonds and C—H⋯π interactions.