Synthesis and insecticidal activities of novel N-sulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. 2. N-substituted phenoxysulfenate derivatives

Design and synthesis of novel 2-(6-thioxo-1,3,5-thiadiazinan-3-yl)-N'-phenylacethydrazide derivatives as potential fungicides

A series of novel 2-(6-thioxo-1,3,5-thiadiazinan-3-yl)-N'-phenylacethydrazide derivatives were designed, synthesized and evaluated for their antifungal activities against Fusarium graminearum (Fg), Rhizoctonia solani (Rs), Botrytis cinerea (Bc) and Colletotrichum capsici (Cc). The bioassay results in vitro showed that most of the title compounds exhibited impressive antifungal activities against the above plant fungi. Particularly, the compounds 5c, 5f, 5g, 5i, 5m and 5p displayed desirable anti-Rs activities, with the corresponding EC₅₀ values of 0.37, 0.32, 0.49, 0.50, 0.46 and 0.45 µg/mL, respectively, which are superior to the positive control carbendazim (0.55 µg/mL). Further in vivo bioassay results showed that the anti-Rs activity of title compound 5f at 200 µg/mL reached 95.84% on detached rice leaves and 93.96% on rice plants. Featuring convenient synthesis, novel structures and desirable antifungal activity, these 2-(6-thioxo-1,3,5-thiadiazinan-3-yl)-N'-phenylacethydrazide derivatives could be further studied as the potential candidates of novel agricultural fungicides.

Ligand-free Cu(ii)-mediated aerobic oxidations of aldehyde hydrazones leading to N,N'-diacylhydrazines and 1,3,4-oxadiazoles

A Cu(ii)-mediated synthesis of N,N'-diacylhydrazines and 1,3,4-oxadiazoles from aldehyde hydrazones has been developed. This is the first time that the synthesis of N,N'-diacylhydrazines and 1,3,4-oxadiazoles using N,N-dimethylamides as the acylation reagent and O₂ in air as the oxidation reagent is reported. These reactions offered several advantages including simple workups, ligand-free inexpensive metal salts as mediators, high yields, and wide scope of substrates.

Synthesis and Larvicidal Activity of Novel Thenoylhydrazide Derivatives

A pair of chemical isomeric structures of novel N-tert-butylphenyl thenoylhydrazide compounds I and II were designed and synthesized. Their structures were characterized by MS, IR, ¹H NMR, elemental analysis and X-ray single crystal diffraction. The regioselectivity of the Meerwein arylation reaction and the electrophilic substitution reaction of N-tert-butyl hydrazine were studied by density functional theory (DFT) quantum chemical method. The larvicidal tests revealed that some compounds I had excellent larvicidal activity against Culex pipiens pallens. As the candidates of insect growth regulators (IGRs), the larval growth inhibition and regulation against Culex pipiens pallens were examined for some compounds, especially I1 and I7. Compounds I1 and I7 were further indicated as an ecdysteroid agonist by reporter gene assay on the Spodoptera frugiperda cell line (Sf9 cells). Finally, a molecular docking study of compound I7 was conducted, which was not only beneficial to understand the structure-activity relationship, but also useful for development of new IGRs for the control of mosquitos.

Synthesis, biological activities and SAR studies of novel 1-Ethyl-7-methyl-4-oxo-1,4-dihydro-[1,8]naphthyridine-3-carboxylic acid based diacyl and sulfonyl acyl hydrazines

BACKGROUND

Diacyl hydrazines have attracted significant interest in medicine, pesticide chemistry and material science. It is an important class of insect growth regulators. In this study, acyl hydrazine, the essential active group was incorporated in to nalidixic acid with the aim of combining the active groups to generate more potent agrochemical.

RESULTS

Various nalidixic acid based diacyl and sulphonyl acyl hydrazines derivatives were synthesized and characterized by spectral techniques. These compounds were screened for the antifungal activity against five pathogenic fungi, nitrification inhibitory activity and insect growth regulator (IGR) activity against Spodoptera litura. The fungicidal activity was screened against R. bataticola, S. rolfsii, R. solani, F. oxysporum and A. porri. Most of the compounds showed moderate to good antifungal activity against A. porri (ED50 = 29.6-495.9 µg/mL). All the compounds showed significant nitrification inhibitory activity at 5% level. IGR activity was examined by feeding method against S. litura.

CONCLUSION

The study revealed that a few compounds possessed good activity against three different pests namely certain fungus, soil bacteria and insect, among which, compound 37 (R' = 4-chlorophenyl) behaved the best.

Design, synthesis, biological activities and 3D-QSAR of new N,N'-diacylhydrazines containing 2,4-dichlorophenoxy moieties

A series of new N,N'-diacylhydrazine derivatives were designed and synthesized. Their structures were verified by 1H-NMR, MS and elemental analysis. The herbicidal activities and plant growth regulating activity of these N,N'-diacylhydrazines were evaluated. The herbicidal activity results showed that most of these N,N'-diacyl-hydrazines showed excellent in vivo activities against Echinochloa crus-galli, Digitaria sanguinalis, Brassica napus, Amaranthus retroflerus. Most of them exhibited higher herbicidal activities against dicotyledonous weeds than monocotyledonous weeds. To further investigate the structure-activity relationship, comparative molecular field analysis (CoMFA) was performed on the basis of herbicidal activity data. Both the steric and electronic field distributions of CoMFA are in good agreement in this work.

Design, synthesis, antifungal activities and 3D-QSAR of new N,N'-diacylhydrazines containing 2,4-dichlorophenoxy moiety

A series of new N,N'-diacylhydrazine derivatives were designed and synthesized. Their structures were verified by 1H-NMR, mass spectra (MS) and elemental analysis. The antifungal activities of these N,N'-diacylhydrazines were evaluated. The bioassay results showed that most of these N,N'-diacylhydrazines showed excellent antifungal activities against Cladosporium cucumerinum, Corynespora cassiicola, Sclerotinia sclerotiorum, Erysiphe cichoracearum, and Colletotrichum orbiculare in vivo. The half maximal effective concentration (EC50) of one of the compounds was also determined, and found to be comparable with a commercial drug. To further investigate the structure-activity relationship, comparative molecular field analysis (CoMFA) was performed on the basis of antifungal activity data. Both the steric and electronic field distributions of CoMFA are in good agreement in this study.

Synthesis, crystal structures, insecticidal activities, and structure--activity relationships of novel N'-tert-Butyl-N'-substituted-benzoyl-N-[di(octa)hydro]benzofuran{(2,3-dihydro)benzo[1,3]([1,4])dioxine}carbohydrazide derivatives

Several series of novel N'-tert-butyl-N'-substituted-benzoyl-N-[di(octa)hydro]benzofuran{(2,3-dihydro)benzo[1,3]([1,4])dioxine}carbohydrazide derivatives Ia, Ib, IIa-IIg, IIIa, IIIb, and Va-Vc were designed and synthesized. Their structures were confirmed by (1)H NMR spectra, HRMS, and X-ray single-crystal structures. The larvicidal activities against oriental armyworm, beet armyworm, diamond-back moth, and corn borer of these compounds were evaluated and contrasted with those of RH-2485, JS-118, and ANS-118. The larvicidal activities against oriental armyworm indicate that monosubstituent or multisubstituents and the substituting group position cannot promote increasing activities and that the cycle region in the general structure of IIa-IIg is much more sensitive to activity than that in the general structure of Ia and Ib. The space volume of the A ring in the structure of Va cannot be too large; if it is, the activity will be decreased significantly. Stomach toxicities against beet armyworm, diamond-back moth, and corn borer of compounds Ia, Ib and IIg indicate that benzoheterocyclic analogues of N-tert-butyl-N,N'-diacylhydrazines show significant selectivities to different lepidopterous pests.

China: forward to the green pesticides via a basic research program

The 973 Program is China's keystone national research program established to support basic research in natural and physical sciences. In addition to promoting the development of core technology and scientific infrastructure needed to enable China to meet the social and economic challenges of the 21st century, the training and mentoring of the new generation of China's young scientists are also important objectives of this national program. The green chemical pesticide research program is a part of the 973 Program. The main objectives of stage 1 of the green chemical pesticide research program (2003-2008) are to establish China's capability to conduct basic research in the discovery of "green" crop protection chemicals that are not only novel in mode of action and highly selective to pest species that are unique to China's agricultural situation but also possess favorable environmental and human hazard and risk potentials. The target-based discovery strategy was selected as the main discovery platform. This strategy not only provided this research program the best chance to discover new products but also provided members of this research team opportunities to establish core technologies in chemoinformatics/computation-aided pesticide design using QSAR, QAAR, sensitive and selective bioassay methodology, combinatorial synthesis, hit to lead optimization, and biological targets that were derived from resistance-AChE, IGR, nAChR, etc. On the basis of the learning from stage 1, stage 2 (2010-2014) of this program will focus on the molecular target-oriented innovation of green chemical pesticides. This commentary presents key learnings and accomplishments from the stage 1 of China's green chemical pesticide research program. It is hoped that this information will stimulate further constructive collaborations between pesticide scientists from China and abroad.

Synthesis and insecticidal activities of novel N-sulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. 3. N-(alkyldithio), n-(aminothio), and N,N-dithio derivatives

A series of novel N-(alkyldithio) and N-aminothio derivatives of N'-tert-butyl-N,N'-diacylhydrazines were designed and synthesized as insect growth regulators via the key intermediates N-chlorosulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. A series of novel N,N-dithio derivatives were also designed and synthesized with N'-tert-butyl-N,N'-diacylhydrazines and sulfur chloride in the presence of sodium hydride. Compared to the parent compounds, these derivatives displayed better solubility and improved hydrophobicities. The insecticidal activities of the target compounds were evaluated. The results of bioassays showed that the target compounds possessed comparable activities against oriental armyworm with the corresponding parent compounds. In particular, N-(morpholinosulfenyl)-N'-tert-butyl-N-4-ethylbenzoyl-N'-3,5-dimethylbenzoylhydrazide (IIIk) has higher toxicities against oriental armyworm and diamondback moth than the parent compound, RH-5992.