Zheng-Ming Li

Synthesis, antifungal activities and 3D-QSAR study of N-(5-substituted-1,3,4-thiadiazol-2-yl)cyclopropanecarboxamides

A series of cyclopropanecarboxamide were prepared and tested for antifungal activity in vivo. The preliminary bioassays indicated that some compounds are comparable to the commercial fungicides. To further explore the comprehensive structure-activity relationship on the basis of fungicidal activity data, comparative molecular field analysis (CoMFA) was performed, and a statistically reliable model with good predictive power (r(2)=0.8, q(2)=0.516) was achieved. Based on the CoMFA, compound 7p was designed and synthesized, which was found to display a good antifungal activity (79.38%) as 7g and 7h.

Synthesis and Insecticidal Activities of Novel Anthranilic Diamides Containing Modified N-Pyridylpyrazoles

In order to look for novel insecticides targeting the ryanodine receptor, four new series of anthranilic diamides containing modified N-pyridylpyrazoles were designed and synthesized. All of the compounds were characterized and confirmed by (1)H NMR, (13)C NMR, and HRMS. The single crystal structure of 10c was determined by X-ray diffraction. Their insecticidal activities against oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella) indicated that most of the compounds showed moderate to high activities at the tested concentration, while compound 19 showed comparable higher activity at the concentration of 0.125 mg/L. The preliminary structure-activity relationship (SAR) was discussed.

Design, synthesis and antifungal activities of novel pyrrole alkaloid analogs

A series of novel analogs of pyrrole alkaloid were designed and synthesized by a facile method and their structures were characterized by 1H NMR, 13C NMR and high-resolution mass spectrometry (HRMS). The structure of compound 2a was identified by 2D NMR including heteronuclear multiple-quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC) and H-H correlation spectrometry (H-H COSY) spectra. Their antifungal activities against five fungi were evaluated, and the results indicated that some of the title compounds showed moderate fungicidal activities in vitro against Alternaria solani, Cercospora arachidicola, Fusarium omysporum, Gibberella zeae and Physalospora piricola at the dosage of 50 μg mL(-1). Compound 2a and 3a exhibited good activities against P. piricola at low dosage.

Design, Synthesis, Biological Activities, and 3D-QSAR of New N,N′-Diacylhydrazines Containing 2-(2,4-dichlorophenoxy)propane Moiety

A series of new N,N′‐diacylhydrazine derivatives were synthesized efficiently under microwave irradiation. Their structures were characterized by 1H NMR, MS, and elemental analysis. Various biological activities of these compounds were tested. Most of them exhibited higher herbicidal activities against dicotyledonous weeds than monocotyledonous weeds. In addition, favorable in vivo fungicidal activities were also found of these compounds against Cladosporium cucumerinum, Corynespora cassiicola, Sclerotinia sclerotiorum(Lib.)de Bary, Erysiphe cichoracearum, and Colletotrichum orbiculare (Berk aLMont) Arx. All compounds displayed excellent plant growth regulatory activities: 100% inhibition was achieved against the radicle growth of cucumber. To further investigate the structure–activity relationship, comparative molecular field analysis was performed on the basis of herbicidal activity data, resulting in a statistically reliable model with good predictive power (r2 = 0.913, q2 = 0.556). Based on the calculation, five additional novel compounds were designed and synthesized. Satisfyingly, compound 4u displayed excellent herbicidal activity (94.7%) at 1500 g/ha, although it is less active than 2,4‐D. Meanwhile, this compound also exhibited good fungicidal activity against C. orbiculare (Berk aLMont) Arx (82.16%).

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, insecticidal activities, and SAR studies of novel pyridylpyrazole acid derivatives based on amide bridge modification of anthranilic diamide insecticides.

Anthranilic diamides are one of the most important classes of modern agricultural insecticides. To discover new structure-modified compounds with high activity, series of novel carbonyl thioureas, carbonyl ureas, oxadiazoles, carbonyl thiophosphorylureas, oxadiazole-containing amides, and thiazoline-containing amides were designed through the modification of the amide bridge based on the structure of chlorantraniliprole and were synthesized, and bioassays were carried out. The compounds were characterized and confirmed by melting point, IR, (1)H NMR, and elemental analyses or HRMS. Preliminary bioassays indicated that some compounds exhibited significant insecticidal activities against oriental armyworm, diamondback moth, beet armyworm, corn borer, and mosquito. Among them, trifluoroethoxyl-containing carbonyl thiourea 20a showed best larvicidal activity against oriental armyworm, with LC50 and LC95 values of 0.1812 and 0.7767 mg/L, respectively. Meanwhile, 20c and 20e showed 86 and 57% death rates against diamondback moth at 0.005 mg/L, and the LC50 values of the two compounds were 0.0017 and 0.0023 mg/L, respectively, which were lower than that of the control chlorantraniliprole. The relationship between structure and insecticidal activity was discussed, and the HF calculation results indicated that the carbonyl thiourea moiety plays an important role in the insecticidal activity. The present work demonstrated that the trifluoroethoxyl-containing carbonyl thioureas can be used as lead compounds for further development of novel insecticides.

Synthesis and biological activity of some novel trifluoromethyl-substituted 1,2,4-triazole and bis(1,2,4-triazole) mannich bases containing piperazine rings.

A series of trifluoromethyl-substituted 1,2,4-triazole Mannich base 6 and bis(1,2,4-triazole) Mannich base 7 containing pyrimidinylpiperazine rings via the Mannich reaction were synthesized and characterized by infrared (IR), (1)H nuclear magnetic resonance (NMR), and elemental analysis. The fungicidal tests indicated that most of compounds 6 and 7 possessed excellent fungicidal activity. Among 19 novel compounds, some showed superiority over commercial fungicides Dimethomorph, Thiophanate-methyl, Iprodione, and Zhongshengmycin. Some compounds also exhibited favorable herbicidal activity in the preliminary studies. On the basis of the comparative molecular field analysis (CoMFA), five novel compounds were subsequently synthesized, their activities were estimated fairly accurately, and compounds 6-A1 and 7-A2 displayed good fungicidal activity against Pseudoperonospora cubensis (96.9 and 84.9%) as 6h and 7c, respectively.

Synthesis and antiviral activity of new acrylamide derivatives containing 1,2,3-thiadiazole as inhibitors of hepatitis B virus replication.

A series of new acrylamide derivatives containing 1,2,3-thiadiazole were synthesized, characterized, and evaluated for their anti-hepatitis B virus (HBV) activities in vitro. The IC50 of compounds 9b (10.4 microg/mL), 9c (3.59 microg/mL) and 17a (9.00 microg/mL) of the inhibition on the replication of HBV DNA were higher than that of the positive control lamivudine (14.8 microg/mL). Compound 9d exhibited significant activity against secretion of HBeAg (IC50=12.26 microg/mL).

Synthesis and antifungal activities of new pyrazole derivatives via 1,3-dipolar cycloaddition reaction.

A series of cycloadducts‐‐pyrazoles via 1,3‐dipolar cycloaddition reactions of generated nitrilimines with N‐(4‐chloro‐2‐fluorophenyl)maleimide were described. The novel compounds synthesized were characterized by 1H NMR, MS, and elemental analysis. The fungicidal tests showed that most of the title compounds exhibit significant fungicidal activities against Corynespora cassiicola.

Crystal structures of two novel sulfonylurea herbicides in complex with Arabidopsis thaliana acetohydroxyacid synthase.

Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) is the first enzyme in the biosynthetic pathway of the branched‐chain amino acids. It catalyzes the conversion of two molecules of pyruvate into 2‐acetolactate or one molecule of pyruvate and one molecule of 2‐ketobutyrate into 2‐aceto‐2‐hydroxybutyrate. AHAS requires the cofactors thiamine diphosphate (ThDP), Mg2+ and FAD for activity. The herbicides that target this enzyme are effective in protecting a broad range of crops from weed species. However, resistance in the field is now a serious problem worldwide. To address this, two new sulfonylureas, monosulfuron and monosulfuron ester, have been developed as commercial herbicides in China. These molecules differ from the traditional sulfonylureas in that the heterocyclic ring attached to the nitrogen atom of the sulfonylurea bridge is monosubstituted rather than disubstituted. The structures of these compounds in complex with the catalytic subunit of Arabidopsis thaliana AHAS have been determined to 3.0 and 2.8 Å, respectively. In both complexes, these molecules are bound in the tunnel leading to the active site, such that the sole substituent of the heterocyclic ring is buried deepest and oriented towards the ThDP. Unlike the structures of Arabidopsis thaliana AHAS in complex with the classic disubstituted sulfonylureas, where ThDP is broken, this cofactor is intact and present most likely as the hydroxylethyl intermediate.