Cheng-Xia Tan

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%).

Microwave Assistant One Pot Synthesis, Crystal Structure, Antifungal Activities and 3D-QSAR of Novel 1,2,4-Triazolo[4,3-a]pyridines

A series of novel 1,2,4‐triazolo[4,3‐a]pyridines were synthesized, and their structures were characterized by 1H NMR, MS, elemental analysis, and single‐crystal X‐ray diffraction analysis. The antifungal activities were evaluated. The antifungal activity results indicated that the compound 2b, 2g, 2p, and 2i exhibited good activities. The activity of compound 2b, 2g, 2p, and 2i can compare with the commercial pesticide. The 3D‐QSAR model was developed using CoMFA method. Both the steric and electronic field distributions of CoMFA are in good agreement in this work and will be very helpful in designing a new set of analogues.

Synthesis, crystal structure, herbicidal activities and 3D-QSAR study of some novel 1,2,4-triazolo[4,3-a]pyridine derivatives

BACKGROUND 1,2,4-Triazolo[4,3-a]pyridine derivatives represent a new series of compounds that possess good herbicidal activity against Echinochloa crusgalli (L.) Beauv., Setaria faberii, Digitaria sanguinalis (L.) Scop., Brassica juncea Coss., Amaranthus retroflexus L. and Eclipta prostrata L. RESULTS A total of 23 novel 1,2,4-triazolo[4,3-a]pyridine derivatives were synthesised and identified by (1) H NMR, IR, single-crystal X-ray diffraction, mass-spectroscopic and elemental analysis, and their herbicidal activities were tested against E. crusgalli (L.) Beauv., S. faberii, D. sanguinalis (L.) Scop., B. juncea Coss., A. retroflexus L. and E. prostrata L. at 150 g a.i. ha(-1) . It was found that the title compound 8-chloro-3-(4-propylphenyl)-[1,2,4]-triazolo[4,3-a]pyridine possesses high herbicidal activity and a broad spectrum against the 22 test weeds, with an inhibition effect of about 50% at a dosage of 37.5 g a.i. ha(-1) , and is safe for corn, cotton and rice at a dosage of 150 g a.i. ha(-1) . Furthermore, comparative molecular field analysis contour models were established to study the structure-activity relationship of the title compounds. CONCLUSION It is possible that, with further structure modification, 1,2,4-triazolo[4,3-a]pyridine derivatives, which possess good herbicidal activities, may become novel lead compounds for the development of herbicides against dicotyledonous weeds.

Synthesis, Crystal Structure, and Fungicidal Activity of a Novel 1,2,3-Thiadiazole Compound

Abstract A new 1,2,3-thiadiazole compound, C18H18Cl2N4O2S, has been synthesized and the crystal structure was determined by single crystal X-ray diffraction study. The fungicidal activity of the title compound was determined and the results showed that it displays moderate fungicidal activity. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

Microwave-assisted synthesis of novel fluorinated 1,2,4-triazole derivatives, and study of their biological activity

Microwave irradiation was used for synthesis of a series of novel fluorinated 1,2,4-triazole derivatives. The molecular structures of the compounds were determined by use of 1H NMR and FTIR spectroscopy and MS and HRMS. Study of their biological activity showed most of the compounds had good herbicidal activity.

Microwave Assisted Synthesis, Antifungal Activity and DFT Theoretical Study of Some Novel 1,2,4-Triazole Derivatives Containing the 1,2,3-Thiadiazole Moiety

In order to investigate the biological activity of 1,2,4-triazole compounds, seventeen novel 1,2,4-triazole derivatives containing 1,2,3-thiadiazole moieties were synthesized by multi-step reactions under microwave assisted conditions. The structures were characterized by 1H-NMR, 13C-NMR, MS and elemental analyses. The target compounds were evaluated for their in vivo fungicidal activities against Corynespora cassiicola, Pseudomonas syringae pv. Lachrymans, and Pseudoperonospora cubensis, and the results indicated that some of the title compounds displayed good fungicidal activities. Theoretical calculations on the title compounds were carried out at the B3LYP/6-31G (d,p). level. The full geometry optimization was carried out using the 6-31G(d,p) basis set, and the frontier orbital energy, atomic net charges were discussed, and the structure-activity relationships were also studied.

Facile and efficient synthesis and herbicidal activity determination of novel 1,2,4-triazolo[4,3-a]pyridin-3(2H)-one derivatives via microwave irradiation

A series of novel 1,2,4-triazolo[4,3-a]pyridin-3(2H)-one derivatives were synthesized and identified by (1)H NMR, single crystal X-ray diffraction, elemental analysis or HRMS, and their herbicidal activities were determined at different concentrations. It was found that some of the title compounds possess high herbicidal activity. Furthermore, DFT calculation was used to study the SAR.

Synthesis and insecticidal activity of novel pyrimidine derivatives containing urea pharmacophore against Aedes aegypti.

BACKGROUND Aedes aegypti is a major mosquito vector for the transmission of serious diseases, especially dengue and yellow fever. More than 1 billion people in developing countries are at risk. The widespread and continual use of pesticides can lead to resistant mosquitoes. In order to maintain mosquito control gains, it is critical to develop and evaluate novel bioactive molecules that differ in mode of action from currently used products. RESULTS A series of novel pyrimidine derivatives were designed and synthesized. Their structures were elucidated by proton nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The biological activities of these compounds were tested against Ae. aegypti. Many of them exhibited insecticidal activity against adult and larval mosquitoes. Compound 4d displayed relatively good activity to reach 70% mortality at 2 µg mL-1 . Furthermore, density functional theory calculations were established to study the structure-activity relationship of these novel compounds. CONCLUSION A practical synthetic route for pyrimidine derivatives is presented. This study suggests that these pyrimidine derivatives exhibit some activity against the yellow fever mosquito and, with further structure modification, could be novel lead compounds for the development of insecticides against mosquitoes.

Synthesis, Crystal Structure, and Biological Activity of A Novel 1,2,3-Thiadiazole Compound Containing 1,2,4-Triazole Moiety

Abstract A new 1,2,3-thiadiazole compound containing 1,2,4-triazole moiety, C15H14FN5 O2S2, has been synthesized and the crystal structure was determined by single crystal X-ray diffraction study. The biological activity of the title compound was determined and the results showed that title compounds 10 showed higher inhibition abilities of rape root than the control cyclopropane-1,1-dicarboxylic acid at 100 μg/mL (73%) and weak activity against Echinochloa crusgalli (28%) and KARI (35%) at 100 μg/mL. [Supplementary materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: additional text, figures, tables.] GRAPHICAL ABSTRACT

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.