Qingchun Huang

Syntheses and insecticidal activities of novel 2,5-disubstituted 1,3,4-oxadiazoles

Abstract Nine novel symmetrical and asymmetrical 2,5-disubstituted 1,3,4-oxadiazoles have been synthesized by a facile and mild method with high yield. Meantime, it was found that the fluorine was easy substituted by hydrazine in polyhalogen-substituted aroyl hydrazine. The preliminary bioassay tests show that two of the compounds ( D5 and D6 ) exhibited a significant insecticidal activity (LC 50 =116.02 and 70.93xa0mgxa0l −1 ) on armyworm, Leucania separata Walker. Using the Drug Discovery Workbench (DDW) (Cerius 2 ), structure–activities relationship was studied.

Synthesis and insecticidal activity of new substituted N-aryl-N′-benzoylthiourea compounds

Abstract Eight new substituted N -aryl- N ′-benzoylthioureas have been synthesised by a facile and mild method with high yield at room temperature. The structures of all compounds were confirmed by 1 H NMR, mass and high resolution mass spectroscopy. The preliminary bioassay tests show that two of the compounds ( 5b and 5e ) exhibited a significant insecticidal activity on armyworm, Leucania separata Walker, at 500xa0mgxa0l −1 .

Syntheses and insecticidal activity of new 2-(5-(trifluoromethyl)pyridyloxymethyl)-1,3,4-oxadiazoles

Abstract Eight 2-(5-(trifluoromethyl)pyridyloxymethyl)-1,3,4-oxadiazoles have been designed and synthesized by four-step synthetic route. The structures of all new compounds were confirmed by 1 H NMR, mass and HR mass spectroscopy. The preliminary bioassay tests show that some compounds, especially those having fluorine on the benzene ring ( II 4 and II 5 ), exhibited a significant insecticidal activity on armyworm, Leucania separata Walker , at 500xa0mgxa0l −1 .

Design and Synthesis of Novel Insecticides Based on the Serotonergic Ligand 1-[(4-Aminophenyl)ethyl]-4-[3-(trifluoromethyl)phenyl]piperazine (PAPP)†

1-[(4-Aminophenyl)ethyl]-4-[3-(trifluoromethyl)phenyl]piperazine (PAPP) is a 5-HT(1A) agonist and was reported to display high affinity for serotonin (5-HT) receptor from the parasitic nematode Haemonchus contortus . The present investigation explored the possibility of using PAPP as a lead compound of new insecticides with novel mode of action. On the basis of the PAPP scaffold, a series of 1-arylmethyl-4-[(trifluoromethyl)pyridin-2-yl]piperazine derivatives were designed, synthesized, and evaluated for biological activities against the armyworm Pseudaletia separata (Walker). Bioassays showed that most of the target compounds displayed certain growth-inhibiting activities or larvicidal activities against armyworm. The quantitative structure-activity relationship (QSAR) for growth-inhibiting activities was also analyzed and established.

{[1-(Arylmethyl)piperidin-4-yl]oxy}-(trifluoromethyl)-pyridines: ketanserin analogues with insect growth regulating activity.

A series of {[1‐(arylmethyl)piperidin‐4‐yl]oxy}‐(trifluoromethyl)‐pyridine derivatives were designed and synthesized on the basis of the ketanserin (1) framework, a prototypic mammalian 5‐HT2A receptor antagonist, and the structure–activity relationship (SAR) was also discussed. The result of the bioassay showed that most of the title compounds inhibited the insect growth and exhibited moderate‐to‐good growth regulating activity against the armyworm Pseudaletia separata Walker. Furthermore, the SAR study revealed that, when the determinant feature, interacting with mammalian 5‐HT2A receptor, was preserved, a simplified ArCH2 group greatly contributed to insect growth inhibitory activities. It was also found that the substituted position of the CF3 group at the pyridine ring played a key role, and that the introduction of 1‐[bis(4‐fluorophenyl)methyl]piperazine, an equivalent of the benzoylpiperidine moiety of ketanserin, resulted in bioactivities similar to those of the title compounds, which were in agreement with the model of ketanserin analogues binding to mammalian 5‐HT2 receptors.

Novel Heterocyclic Compounds Containing Sulfur: Synthesis and Insecticidal Activity of (2-Chlorothiazol-5-yl)methyl 2-Phenyliminothiazolidines

A series of new (2-chlorothiazol-5-yl)methyl 2-phenyliminothiazolidines were designed and synthesized. All new compounds were characterized by 1 H NMR and, in some cases, by 13 C NMR, IR, and HRMS. They are soluble in most organic solvents, which makes them easier to use. A preliminary bioassay showed that some of the new compounds display insecticidal activity against third-instar larvae of Cx. pipiens pallens at 50 mg/L and moderate insecticidal activity against A. craccivora at 1000 mg/L.

Synthesis and Biological Activity of Novel Symmetrical Bis-2-phenyliminothiazolidine Derivatives

A series of novel symmetrical bis-2-phenyliminothiazolidine derivatives were designed and synthesized. The structures of all the title compounds were characterized by 1H NMR and, in some cases, by 13C NMR, IR, and high-resolution mass spectra. Herbicidal activities were examined, and some of these compounds showed selectively herbicidal activity against Triticum aestivum. The type of linker between the two 2-phenyliminothiazolidines was crucial for the biological activities.

Synthesis and bioactivities of novel neonicotinoids dioxolane compounds

As candidates for the screening of neonicotinoid insecticides, nine novel compounds were designed and synthesised via Mannich reaction of (1,3-dioxolane-4-yl)methyl-2-(nitromethylene) imidazoline with corresponding primary amines and formaldehyde. Preliminary bioassays indicated that most of these compounds had moderate insecticidal activities against pea aphids.