For the first time, the botanic source natural product matrine was reported to have more potent inhibitory activity against tobacco mosaic virus (TMV) than the commercial virucide ribavirin. On the basis of the structural diversity modification strategy, a series of matrine derivatives was synthesized and systematically evaluated for their antiviral activity against TMV, fungicidal activity, and insecticidal activity. As a result, compounds 3 (inhibitory rate 67.3%, 69.5%, 63.7%, 63.0% at 500 μg/mL for in vitro activity, inactivation, curative, and protection activities in vivo, respectively), 16 (66.7%, 60.7%, 63.8%, 68.9% at 500 μg/mL), and 32 (74.6%, 76.9%, 72.3%, 75.7% at 500 μg/mL) were found to have much higher anti-TMV activity than ribavirin (40.8%, 37.5%, 38.2%, 37.7% at 500 μg/mL), even exhibiting as well as NK-007 (70.3%, 66.1%, 68.4%, 67.5% at 500 μg/mL), which was an efficient compound created by our group previously. At the same time, it was found that matrine and its derivatives had a broad spectrum fungicidal activity (14 fungi), especially the inhibition of compound 32 against Phytophthora capsici Leonian reached 96.4% at a concentration of 50 μg/mL. What’s more, all compounds exhibited very good insecticidal activity to five kinds of insects (including Mythimna Separate, Helicoverpa Armigera, Ostrinia Nubilalis, Plutella xylostella, and Culex Pipiens Pallens); especially, the inhibition rate of C. Pipiens Pallens of compound 22 could still reach 70% at 1 μg/mL.Keywords: anti-TMV activity; fungicidal activity; insecticidal activity; matrine; natural product of plant sources; structure−activity relationship;

Enormous compounds containing sulfone/sulfoxide groups have been used in a variety of fields, especially in drug and pesticide design. To search for novel environmentally benign and ecologically safe pesticides with unique modes of action, a series of 2,4-diphenyl-1,3-oxazolines containing sulfone/sulfoxide groups as chitin synthesis inhibitors (CSIs) were designed and synthesized on the basis of the sulfonylurea receptor protein-binding site for CSIs. Their structures were characterized by 1H and 13C nuclear magnetic resonance and high-resolution mass spectrometry. The acaricidal and insecticidal activities of the new compounds were evaluated. It was found that most of the target compounds displayed wonderful acaricidal activities against spider mite (Tetranychus cinnabarinus) larvae and eggs. Especially compounds I-4, II-3, and II-4 displayed higher activities than commercial etoxazole at a concentration of 2.5 mg L–1. Some target compounds exhibited insecticidal activities against lepidopteran pests. The present work demonstrated that these compounds containing sulfone/sulfoxide groups could be considered as potential candidates for the development of novel acaricides in the future.

A series of new pymetrozine analogues containing both methyl on the imine carbon and phenoxy group at the pyridine ring were designed and synthesized. Their insecticidal activities against bean aphid (Aphis craccivora), mosquito larvae (Culex pipiens pallens), cotton bollworm (Helicoverpa armigera), corn borer (Ostrinia nubilalis) and oriental armyworm (Mythimna separata) were evaluated. The results of bioassays indicated that most of the target compounds showed good insecticidal activity against bean aphid; especially, IIIf (80%) and IIIl (80%) exhibited higher aphicidal activity than pymetrozine (30%) at 5 mg/kg, and the two compounds still showed 20% and 30% mortality at 2.5 mg/kg, respectively, whereas pymetrozine displayed no activity at the same concentration. These compounds exhibited a completely different structure–activity relationship to that of known pymetrozine derivatives, in which it is thought introducing alkyl group on the imine carbon could be detrimental to the activities. Our new result suggested that the methyl on the imine carbon and phenoxy group at the pyridine ring of phenoxy group may play additive effects on the improvement of aphicidal activity. Besides this, compound IIIs, containing an allyl at the para position of phenoxy group, exhibited excellent insecticidal activity against mosquito larvae, lepidoptera pests cotton bollworm, corn borer and oriental armyworm.

Numerous compounds containing urea bridge and biurea moieties are used in a variety of fields, especially as drugs and pesticides. To search for novel, environmentally benign and ecologically safe pesticides with unique modes of action, four series of novel triazone analogues containing urea, thiourea, biurea, and thiobiurea bridge, respectively, were designed and synthesized, according to various calcium ion channel inhibitors which act on transient receptor potential protein. Their structures were characterized by \({}^{1}\mathrm{H}\) NMR, \({}^{13}\mathrm{C}\) NMR, and HRMS. The insecticidal activities of the new compounds were obtained. The bioassay results indicated that compounds containing a thiourea bridge and a thiobiurea bridge exhibited excellent insecticidal activities against bean aphid. Specifically, compounds \({\mathbf{VIb}}_{15}\), \({\mathbf{VIIb}}_{8}\), and \({\mathbf{VIIb}}_{9}\) exhibited 85, 90, and 95 % activities, respectively, at 10 mg/kg. Compounds \({\mathbf{VIb}}_{14}\) (30 %), \({\mathbf{VIIb}}_{10}\) (35 %), \({\mathbf{VIIb}}_{11}\) (30 %), and \({\mathbf{VIIb}}_{12}\) (40 %) exhibited the approximate aphicidal activity of pymetrozine (30 %) at 5 mg/kg. In addition, some target compounds exhibited insecticidal activities against lepidopteran pests. From a molecular design standpoint, the information obtained in this study could help in the further design of new derivatives with improved insecticidal activities.

4-(Dimethylamino)pyridine functioned as an excellent catalyst for iodolactonisation reactions of γ,δ-unsaturated carboxylic acids, affording γ-lactones, δ-lactones, or both under neutral conditions at room temperature. The effects of substrate structures on the iodolactonisation were investigated, and a catalytic mechanism is proposed.

On the basis of etoxazole, a series of novel 2-(2,6-difluorophenyl)-4-(4-substituted phenyl)-1,3-oxazolines containing a sulfur ether moiety were designed and synthesized via the key intermediate N-(1-(4-(bromomethyl)phenyl)-2-chloroethyl)-2,6-difluorobenzamide. The bioassay results showed that most of these designed target compounds exhibited excellent acaricidal activity against both the eggs and larvae of Tetranychus cinnabarinus, especially the eggs. Among compounds with high activity against the eggs of mites, the LC50 values of 2, 11, 17, and 19 were 0.0003, 0.0002, 0.0005, and 0.0008 mg L–1, respectively, much lower than that of etoxazole (0.0089 mg L–1). Compound 2 was chosen to evaluate the acaricidal activity in the field, and the results displayed that at a concentration of 22 mg kg–1, 2 had a much better control effect than etoxazole against both T. cinnabarinus and P. latus on eggplant. Some compounds also showed good insecticidal activities against oriental armyworm and mosquito. On the basis of our research, the newly found structure–activity relationship may guide the development of new acaricides/pesticides that are required in the agriculture market.

Two series of novel 2,4-diphenyl-1,3-oxazolines containing an oxime ether moiety were designed and synthesized via the key intermediate N-(2-chloro-1-(p-tolyl)ethyl)-2,6-difluorobenzamide. The bioassay results showed that the target compounds with an oxime ether substituent at the para position of 4-phenyl exhibited excellent acaricidal activity against Tetranychus cinnabarinus in the laboratory. Moreover, all of the target compounds had much higher activities than etoxazole, as the ovicidal and larvicidal activities of the target compounds I-a–I-l and II-a–II-n against T. cinnabarinus were all over 90% at 0.001 mg L–1, but etoxazole gave only 30% and 40% respectively at the same concentration. The activity order of compounds with regard to acaricidal activity in vivo was almost consistent with their affinity activity with sulfonylurea receptor (SUR) of Blattella germanica in vitro, hence, it was supposed that the acaricidal mechanism of action of the target compounds was that they can bind with the site of SUR and therefore inhibit chitin synthesis. Moreover, the eminent effect of the compound II-l, [2-(trifluoromethyl)benzaldehyde O-(4-(2-(2,6-difluorophenyl)-4,5-dihydrooxazol-4-yl)benzyl) oxime], against Panonychus citri and T. cinnabarinus in the field indicated that II-l exhibited a promising application prospect as a new candicate for controlling spider mites in the field.

On the basis of the structures of chlorfenapyr and dioxapyrrolomycin, a series of 2-benzylpyrroles with a hydroxyl, an alkyloxy, an acyloxy, an alkylsulfanyl, or an oxime moiety at the α-position of benzyl were designed and synthesized. Their insecticidal, acaricidal, and fungicidal activities were extensively investigated. The structure–activity relationship showed that benzylpyrroles bearing shorter α-alkyloxy groups gave better activities against most of the insect species; the alkylation of pyrrole usually gave increased activity. Among all compounds, (4-bromo-2-(α-(2,2,2-trifluoroethoxy)-4-chlorobenzyl)-1-(ethoxymethyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile) (5′j) exhibited the most outstanding insecticidal activities against oriental armyworm (IC50 = 10 mg L–1), diamondback moth (0.07 mg L–1), corn borer (50 mg L–1), and mosquito (0.04 mg L–1), which are very close to those of chlorfenapyr (5, 0.08, <25, and <0.025 mg L–1, respectively). In addition, some compounds also exhibited a broad or selective fungicidal spectrum.

On the basis of complex I receptor protein binding site and commercial tebufenpyrad and tolfenpyrad, four series of novel pyrazole-5-carboxamides containing imine, oxime ether, oxime ester, and dihydroisoxazoline were designed and synthesized via the key intermediate 4-chloro-3-ethyl-N-(4-formylbenzyl)-1-methyl-1H-pyrazole-5-carboxamide. The structures of target compounds were confirmed by 1H NMR and high-resolution mass spectrum (HRMS). The results of bioassays indicated that the target compounds possessed good-to-excellent activities against a broad spectrum of insects such as cotton bollworm (Helicoverpa armigera), spider mite (Tetranychus cinnabarinus), bean aphid (Aphis craccivora), and mosquito (Culex pipiens pallens), but gave different structure–activity relationships for each species. Compounds containing imine showed high insecticidal activity against cotton bollworm. Especially, stomach activity of compounds 5-1c was 60% at 11 mg kg–1. The compounds also had good activities against bean aphid and mosquito. The foliar contact activity of compounds 5-1a, 5-1b, 5-1e, 5-3c, and 5-3d against bean aphid were 90, 100, 90, 90, and 90%, respectively, at 200 mg kg–1. The activity of compound containing dihydroisoxazoline moiety (5-4) against mosquito was 60% at 1 mg kg–1, which was near that of tebufenpyrad. The introduction of dihydroisoxazoline structure (5-4) was advantageous to improve the activity of the compound against adult mites compared with other structures; the miticidal activity of 5-4– against adult mites was 60% at 50 mg kg–1.

On the basis of commercial insecticides tebufenpyrad and tolfenpyrad, two series of novel pyrazole-5-carboxamides containing α-hydroxymethyl-N-benzyl or α-chloromethyl-N-benzyl and pyrazoles containing 4,5-dihydrooxazole moieties were designed and synthesized via the key intermediate 2-amino-1-(4-substituted) phenyl ethanol. The structures of target compounds were confirmed by 1H NMR and elemental analysis or high-resolution mass spectrum (HRMS), and their activities against cotton bollworm (Helicoverpa armigera), diamondback moth (Plutella xylostella), bean aphid (Aphis craccivora), mosquito (Culex pipiens pallens), and spider mite (Tetranychus cinnabarinus) were tested. The results of bioassays indicated that compounds containing α-chloromethyl-N-benzyl and compounds containing 4,5-dihydrooxazole showed high insecticidal activity against cotton bollworm. Especially, stomach activities of compounds Ij, Il, and IIe were 60% at 5 mg kg–1. Moreover, the target compounds exhibited high selectivity between cotton bollworm and diamondback moth, although both of them belong to the order Lepidoptera. Although the activities against diamondback moth were at a low level, some of the target compounds exhibited antifeedant activity. The compounds also had good activities against bean aphid, mosquito, and spider mite. The foliar contact activity of compounds Ic, Id, Ie, and IIf against bean aphid were 95, 95, 100, and 95%, respectively, at 200 mg kg–1. The miticidal and ovicidal activities of compound IIi against spider mite were both 95% at 200 mg kg–1. Furthermore, a trivial change at 4-position of pyrazole ring would lead to great changes in properties and activities, which can easily be deduced by comparing the activities of compounds in series I (4-chloro-pyrazole compounds) with corresponding compounds in series II (4-hydro-pyrazole compounds), especially from the miticidal and ovicidal activities of Ii and IIi against spider mite.

4-(Dimethylamino)pyridine functioned as an excellent catalyst for iodolactonisation reactions of γ,δ-unsaturated carboxylic acids, affording γ-lactones, δ-lactones, or both under neutral conditions at room temperature. The effects of substrate structures on the iodolactonisation were investigated, and a catalytic mechanism is proposed.