Synthesis, insecticidal, and acaricidal activities of novel 2-aryl-pyrrole derivatives containing ester groups

A series of novel 2-aryl-pyrrole derivatives containing ester groups were synthesized, and their structures were characterized by (1)H NMR spectroscopy and elemental analysis. The insecticidal activities against oriental armyworm, mosquito, diamondback moth, green rice leafhopper, and bean aphids and acaricidal activities against spider mite of these new compounds were evaluated. The results of bioassays indicated that some of these title compounds exhibited excellent insecticidal and acaricidal activities. The insecticidal activities against oriental armyworm of compounds IVa, IVd, IVe, IVf, IVg, IVi, IVk, and IVp were equal to commercialized Chlorfenapyr, and the insecticidal activities of most of compounds IVb, IVc, IVd, IVf, IVg, IVj, IVk, IVl, IVs, IVt, IVu, IVw, IVx, IVz, and Chlorfenapyr against mosquito at 0.10 mg kg (-1) were 100%, and the acaricidal activities of compounds IVd, IVe, IVf, IVg, IVh, IVi, and IVk were equal or superior to Chlorfenapyr. Especially, the results indicated that the acaricidal activity of [4-bromo-2-(4-chlorophenyl)-3-cyano-5-(trifluoromethyl)pyrrol-1-yl]methyl 3-methylbutanoate ( IVg) against spider mite was 2.65-fold as high as that of Chlorfenapyr from the value of LC 50.     

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

A series of novel N-substituted phenoxysulfenyl- 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. Compared to the parent compounds, these N-substituted phenoxysulfenyl derivatives displayed better solubility and improved hydrophobicities. The insecticidal activities of the new compounds were evaluated. The results of bioassays showed that the title compounds possessed a combination of strong stomach as well as contact poison property higher than the corresponding parent compounds. In particular, N-(4-chlorophenoxy)sulfenyl -N'- tert-butyl- N-4-ethylbenzoyl- N'-3,5-dimethylbenzoylhydrazide ( IIIi) as a field testing candidate has higher stomach toxicities against oriental armyworm and tobacco cutworm than the corresponding parent compound RH-5992. Furthermore, the compound IIIi exhibits higher contact activities against Asian corn borer, tobacco cutworm, and cotton bollworm than RH-5992.     

Synthesis and insecticidal activity of novel carbamate derivatives as potential dual-binding site acetylcholinesterase inhibitors

In biological systems, bivalent ligands often possess increased functional affinity for their receptors compared with monovalent ligands. On the basis of the structure of acetylcholinesterase (AChE), a series of novel carbamate heterodimetic derivatives were designed and synthesized with the aim of increasing the potency toward AChE inhibition. The AChE inhibitory ability of all the novel compounds was tested using AChE obtained from the brain of the housefly. The bioassay results showed that compounds 6j, 6k, 6m, 6n, 6p, and 6q had increased inhibitory activities in comparison with parent phenyl N-methylcarbamate (MH) at the concentration of 100 mg/L. Among them, the most potent AChE inhibitor of these compounds was 6q (IC(50) = 12 μM), which showed 62-fold greater AChE inhibitory activity than that of MH and 12-fold greater activity than metolcarb (MT), which suggested that the 3-nitrophenoxy moiety of compound 6q was able to interact with the aromatic amino acid residues lining the gorge and the phenyl N-methylcarbamate moiety was able to interact with the catalytic sites of AChE, simultaneously. The insecticidal activities of compounds 6j, 6k, 6m, 6n, 6p, and 6q were further evaluated. Consistent with the result in vitro bioassay, those compounds demonstrated better activities against Lipaphis erysimi than parent compound MH at the concentration of 300 mg/L, and compound 6q showed the best insecticidal activity, causing 98% mortality after 24 h of treatment.     

N'-Nitro-2-hydrocarbylidenehydrazinecarboximidamides: design, synthesis, crystal structure, insecticidal activity, and structure-activity relationships

A novel series of acyclic imine-substituted nitenpyram analogues were designed and synthesized from nitroaminoguanidine, and their structures were confirmed using X-ray diffraction crystallography. Preliminary bioassays showed that the target molecules exhibited good activities against aphids in laboratory (Myzus persicae Sulzer) and field trials (M. persicae Sulzer and Brevicoryne brassicae Linnaeus). Comparative molecular field analysis and comparative molecular similarity indices analysis were employed to develop a three-dimensional quantitative structure-activity relationship model that describes the insecticidal activity of 21 neonicotinoid derivatives. Simple synthesis, low cost, and good insecticidal activity have made this series of compounds become very promising candidates for future commercial pesticides.     

Synthesis and insecticidal evaluation of novel N-oxalyl derivatives of tebufenozide

A series of novel N '-tert-butyl-N '-3,5-dimethylbenzoyl-N-aryloxyoxalyl-N-4-ethylbenzoyl hydrazines containing a carboxylic acid or ester substituent on the aryl were synthesized, and their larvicidal activities were evaluated. The results of bioassays indicated that some of these title compounds exhibit higher larvicidal activities than RH5849 (N-tert-butyl-N,N '-dibenzoylhydrazine), but they are not good compared to the parent compound (tebufenozide). The carboxylic acid substituent on the aryl was essential for high larvicidal activity. Compared to the parent compound, these derivatives displayed different physical properties, for example, better solubility in organic solvents. Toxicity assays indicated that these derivatives could induce a premature, abnormal, and lethal larval molt.     

Synthesis and insecticidal activity of some novel fraxinellone-based esters

In continuation of a program aimed at the discovery and development of natural products-based insecticidal agents, two series of novel fraxinellone-based esters were synthesized by modification at the C-4 or C-10 position of fraxinellone and evaluated for their insecticidal activity against the pre-third-instar larvae of Mythimna separata in vivo. An efficient method for the stereoselective synthesis of 4α-hydroxyfraxinellone from fraxinellonone was developed, and the steric configuration of 6h was unambiguously confirmed by X-ray crystallography. Among 37 compounds, some derivatives displayed potent insecticidal activity; especially compounds 6h, 6q, 6t, and 7q showed more promising insecticidal activity than toosendanin, a commercial botanical insecticide derived from Melia azedarach . This suggested that introduction of the fluorine atom on the phenyl ring could lead to a more potent compound than one possessing chlorine or bromine. Meanwhile, introduction of the heterocyclic fragments at the C-4 or C-10 position of fraxinellone was essential for their insecticidal activity. This will pave the way for further design, structural modification, and development of fraxinellone as an insecticidal agent.     

Design, synthesis, structure, and acaricidal/insecticidal activity of novel spirocyclic tetronic acid derivatives containing an oxalyl moiety

A series of novel spirocyclic tetronic acid derivatives containing an oxalyl moiety was designed and synthesized via the key intermediate 3-(2,4,6-trimethyl)-2-oxo-1-oxaspiro[4.4]-decyl-3-en-4-ol. The target compounds were identified by (1)H NMR and elemental analysis or high-resolution mass spectrum (HRMS). The results of bioassays indicated that most of the target compounds possessed excellent acaricidal activities against carmine spider mite larvae and eggs. Especially, diisopropylamino oxalyl compound 7g and piperidine oxalyl compound 7h were 1.4- and 2.3-fold as high as the activities of commercial Spiromesifen, respectively, against spider mite eggs. Moreover, most of the target compounds exhibited insecticidal activities against Lepidoptera pest. Interestingly, compounds containing alkylamino-substituted oxalyl moiety showed obvious selectivity between spider mite larvae and eggs because the activities against spider mite eggs of 7g and 7h were 25-fold those against spider mite larvae, whereas Spiromesifen had no significant differences in these activities. This meant that the introduction of an oxalyl moiety to spirocyclic tetronic acid might lead to novel biological activity characteristics.     

Synthesis and insecticidal activities of novel N-sulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. 1. N-alkoxysulfenate derivatives

A series of novel N-alkoxysulfenyl-N'-tert-butyl-N, N'-diacylhydrazines were designed and synthesized as insect growth regulators by the key intermediates N-chlorosulfenyl-N'-tert-butyl-N, N'-diacylhydrazines, which were prepared for the first time. Compared to N'-tert-butyl-N, N'-diacylhydrazines, these N-alkoxysulfenyl derivatives displayed better solubility and improved hydrophobicities. The insecticidal activities of the new compounds were evaluated. The results of bioassays showed that the title compounds possessed a combination of strong stomach as well as contact poison property higher than the corresponding parent compounds. In particular, N-methoxysufenyl-N'-tert-butyl-N-4-ethylbenzoyl-N'-3,5-dimethylbenzoylhydrazide (IIIf) as a field testing candidate has higher stomach toxicities against oriental armyworm and beet armyworm than the corresponding parent compound RH-5992. Furthermore, the compound IIIf exhibits higher contact activities against oriental armyworm, Asian corn borer, tobacco cutworm, and cotton bollworm than RH-5992. The sulfenyl substituent was essential for high larvacidal activity.     

Design, synthesis, crystal structure analysis, and insecticidal evaluation of phenylazoneonicotinoids

On the basis of research of the proposed modes of action between neonicotinoids and insect nicotinic acetylcholine receptor (nAChR), a series of phenylazoneonicotinoids were designed and synthesized to further promote the π-π interaction between molecule and amino acid residues. The target compounds have been identified on the basis of satisfactory analytical and spectral ((1)H NMR, (13)C NMR, HRMS, and X-ray) data. The preliminary results revealed that tiny differences in substitutes resulted in different configurations and great bioactivity variations. Some compounds with electron-donating groups on positions 2 and 6 of the phenyl ring presented higher insecticidal activity than imidacloprid against cowpea aphids ( Aphis craccivora ). The impressive crystal structure of the excellent insecticidal activity compound 9q clearly proved that the functional electronegative pharmacophore was approximately vertical to the methyleneimidazolidine plane. The differences in the mode of interaction on nAChR of typical compounds 9h and 9q remain unclear.     

Synthesis, fungicidal, and insecticidal activities of beta-Methoxyacrylate-containing N-acetyl pyrazoline derivatives

1-Acetyl-3,-5-diarylpyrazolines have received considerable interests from the fields of medicinal and agricultural chemistry due to their broad spectrum of biological activities. To discover new lead compounds exhibiting both fungicidal and insecticidal activities, a series of pyrazoline derivatives were designed and synthesized by introducing the beta-methoxyacrylate pharmacophore into the scaffold of 1-acetyl-3,5-diarylpyrazoline. The fungicidal activities against Pseudoperoniospora cubensis, Sphaerotheca fuliginea, Botrytis cinerea, and Rhizoctonia solani and the insecticidal activities against Aphis medicagini, Nilaparvata legen, Mythima separata, and Tetranychus cinnabarnus were screened. The most potent compound 13, 1-aceto-3-[m-[o-(E-1-methoxycarboxyl-2-methoxy)-1-yl]benzyloxy]phenyl-5-(benzo-[1,3]-dioxolyl)-4,5-dihydro- pyrazoline, was identified. Its fungicidal IC(50) values against P. cubensis and S. fuliginea are 26.6 and 57.6 microg mL(-1), respectively, while its insecticidal LC(50) value against M. separata is 26.6 microg mL(-1). These results indicated that compound 13 could be used as a lead for further developing new pyrazoline type products exhibiting both fungicidal and insecticidal activities.     

Synthesis and antiviral activity of novel chiral cyanoacrylate derivatives

2-Cyanoacrylate is an important kind of herbicide targeted in photosystem II. Starting from cyano ethyl acetate, the chiral title compounds were synthesized under microwave irradiation, which has the advantages of shorter reaction time, higher yield, and simpler procedure. A half-leaf method was used to determine the inhibition and curative efficacies of the eight chiral products against tobacco mosaic virus in vivo. It was found that chiral compound IIc-R possesses moderate inhibition and curative effect in vivo with rates of 89.1 and 43.1%, respectively. In the MTT test, these new chiral compounds were found to possess weak antiproliferation activities to PC3 and A431 cells.     

Synthesis and insecticidal activity of N-tert-butyl-N,N'-diacylhydrazines containing 1,2,3-thiadiazoles

N-tert-Butyl-N,N'-diacylhydrazines are nonsteroidal ecdysone agonists used as environmental benign pest regulators. In this paper, two series of new N-tert-butyl-N,N'-diacylhydrazine derivatives containing 1,2,3-thiadiazole were designed and synthesized. All structures of the synthesized compounds were confirmed by proton nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS). Bioasssay results indicated that most of the synthesized compounds possessed good insecticidal activities against Plutella xylostella L. and Culex pipiens pallens as compared with the positive control, tebufenozide. The results of this study indicated that 1,2,3-thiadiazoles, as an important active substructure, could improve or maintain the activity of the dicylhydrazines and favor novel pesticide development.     

Synthesis, insecticidal activity, and QSAR of novel nitromethylene neonicotinoids with tetrahydropyridine fixed cis configuration and exo-ring ether modification

To keep the nitro group in the cis position, a series of nitromethylene neonicotinoids containing a tetrahydropyridine ring with exo-ring ether modifications were designed and synthesized. All of the compounds were characterized and confirmed by 1H NMR, high-resolution mass spectroscopy, elemental analysis, and IR. The bioassay tests showed that some of them exhibited good insecticidal activities against pea aphids. On the basis of 10 nitromethylene derivatives, the quantitative structure-bioactivity relationship (QSAR) was analyzed and established. The results suggested that AlogP98 and Dipole_Mopac might be the important parameters related with biological activities.     

Dihydropiperazine neonicotinoid compounds. Synthesis and insecticidal activity

Syntheses of various isomeric dihydropiperazines can be approached successfully by taking advantage of the regioselective monothionation of their respective diones. Preparation of the precursor unsymmetrical N-substituted piperazinediones from readily available diamines is key to this selectivity. The dihydropiperazine ring system, as exemplified in 1-[(6-chloropyridin-3-yl)methyl]-4-methyl-3-oxopiperazin-2-ylidenecyanamide (4) and 1-[(2-chloro-1,3-thiazol-5-yl)methyl]-4-methyl-3-oxopiperazin-2-ylidenecyanamide (25), has been shown to be a suitable bioisosteric replacement for the imidazolidine ring system contained in neonicotinoid compounds. However, placement of the cyanoimino electron-withdrawing group further removed from the pyridine ring, as in 4-[(6-chloropyridin-3-yl)methyl]-3-oxopiperazin-2-ylidenecyanamide (3a), or relocation of the carbonyl group, as in 1-[(6-chloropyridin-3-yl)methyl]-4-methyl-5-oxopiperazin-2-ylidenecyanamide (5), results in significantly decreased bioisosterism. The dihydropiperazine ring system of 4 and 25 also lends a degree of rigidity to the molecule that is not offered by the inactive acyclic counterpart 2-[(6-chloropyridin-3-yl)-methyl-(methyl)amino]-2-(cyanoimino)-N,N-dimethylacetamide (6). A pharmacophore model is proposed that qualitatively explains the results on the basis of good overlap of the key pharmacophore elements of 4 and imidacloprid (1); the less active regioisomers of 4 (3a, 5, and 6) feature a smaller degree of overlap.     

Synthesis and herbicidal activity of novel 3-aminocarbonyl-2-oxazolidinethione derivatives containing a substituted pyridine ring

A series of 3-aminocarbonyl-2-oxazolidinethione derivatives containing a substituted pyridine ring were designed and synthesized. The structures of all of the title compounds were characterized by 1H NMR, 13C NMR, IR, and HRMS. Their agricultural bioactivities were evaluated, and some of these compounds exhibited good herbicidal activities against Echinochloa crusgalli, Sorghum vulgare, Digitaria sanguinalis, Eclipta prostrasta, Cucumis sativus, and Brassica campestris, which were associated mainly with their steric properties and lipophilicities based on the structure-activity relationship discussion.     

Synthesis and fungicidal activity of novel 2-oxocycloalkylsulfonylureas

A series of 2-oxocycloalkylsulfonylureas (2) have been synthesized in a six-step, three-pot reaction sequence from readily available cyclododecanone, cycloheptanone, and cyclohexanone. Their structures were confirmed by IR, 1H NMR, and elemental analysis. The bioassay indicated that some of them possess certain fungicidal activity against Gibberella zeae Petch. In general, compounds containing a 12-membered ring (2A) are more active than those containing a 6- or 7-membered ring (2B, 2C). In the series 2A, the compounds in which R is a disubstituted phenyl or pyrimidyl showed better activity than those in which R is a monosubstituted phenyl or pyrimidyl, and aryl-substituted compounds have somewhat higher activity than those substituted by pyrimidyl. The further bioassay showed that the representative of 2A, 2A15, has good fungicidal activities against not only G. zeae Petch but also Botrytis cinerea Pers, Colletotrichum orbiculare Arx, Pythium aphanidermatum Fitzp, Fusarium oxysporum Schl. f. sp. Vasinfectum, etc.     

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.     

Synthesis, crystal structure, and biological activities of 2-cyanoacrylates containing furan or tetrahydrofuran moieties

A series of novel cyanoacrylates containing furan or tetrahydrofuran moieties were synthesized, and their structures were characterized by 1H NMR, elemental analysis, and single-crystal X-ray diffraction analysis. The herbicidal, plant growth regulatory, fungicidal, and antiviral activities of these cyanoacrylates were evaluated. The results of herbicidal activities showed that most of these cyanoacrylates exhibited higher herbicidal activities against dicotyledonous weeds than monocotyl-edonous weeds, and the compounds containing the tetrahydrofuran moiety gave higher herbicidal activities than corresponding furan analogues; (Z)-ethoxyethyl 2-cyano-3-isopropyl-3-(tetrahydrofuran-3-yl)methaneaminoacrylate showed excellent herbicidal activities against amaranth pigweed in postemergence treatment at a dose of 375 g/ha. At the same time, these cyanoacrylates had interesting plant growth regulatory activities, and some compounds stimulated radicle growth of cucumber, whereas some compounds had an inhibitory effect. These cyanoacrylates showed fungicidal activities as well.     

Synthesis and insecticidal activities of novel anthranilic diamides containing acylthiourea and acylurea

Two series of anthranilic diamides containing acylthiourea and acylurea linkers were designed and synthesized, with changed length and flexibility of the linkers to compare to known anthranilic diamide insecticides. In total, 26 novel compounds were synthesized, and all compounds were characterized by (1)H nuclear magnetic resonance and high-resolution mass spectrometry. Their insecticidal activities against oriental armyworm ( Mythimna separata ), mosquito larvae ( Culex pipiens pallens ), and diamondback moth ( Plutella xylostella ) were evaluated. The larvicidal activities against oriental armyworm indicated that the introduction of acylthiourea into some structures could retain their insecticidal activity; 8 of the 15 compounds (13a-13e, 14a-14e, and 15a-15e) exhibited 100% larvicidal activity at 10 mg/L. However, the introduction of acylurea decreased the insecticidal activity; only 3 of the 11 compounds (17a-17k) exhibited 100% larvicidal activity at 200 mg/L. The whole-cell patch-clamp technique indicated that compound 13b and chlorantraniliprole exhibited similar effects on the voltage-gated calcium channel. The calcium-imaging technique was also applied to investigate the effects of compounds 13b and 15a on the intracellular calcium ion concentration ([Ca(2+)](i)), which indicated that they released stored calcium ions from endoplasmic reticulum. Experimental results denoted that several new compounds are potential activators of the insect ryanodine receptor (RyR).     

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.