Xing-Hai Liu

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, Dimeric Crystal Structure, and Fungicidal Activity of 1-(4-Methylphenyl)-2-(5-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-4-phenyl-4H-1,2,4-triazol-3-ylthio)ethanone

Abstract A new triazole compound, C46H46N10O2S2, has been synthesized, and the crystal structure was determined by a 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

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.

Phase Transfer–Catalyzed, One-Pot Synthesis of Some Novel N-Pyrimidinyl-N′-nicotinyl Thiourea Derivatives

Abstract A new series of acyl thiourea derivatives were synthesized in one-pot using PEG-600 as the phase transfer catalyst (PTC). The structures of title compounds were characterized by 1H NMR, IR, MS, and elemental analysis. In addition, the fungicidal activity of the acyl thiourea derivatives were tested, which showed that most of them exhibit moderate 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

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.

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, structure and biological activity of novel 1,2,4-triazole mannich bases containing a substituted benzylpiperazine moiety.

A series of novel Mannich bases with trifluoromethyl‐1,2,4‐triazole and substituted benzylpiperazine moieties were synthesized. Their structures were confirmed by IR, 1H NMR and elemental analysis. The single crystal structure of compound 4r was also determined. The preliminary bioassays showed that most of the lead compounds had low herbicidal activity against Brassica campestris, Echinochloa crusgalli, and KARI enzyme. However, most of them exhibited significant fungicidal activity at the dosage of 50 μg/mL toward five test fungi. Among the 18 novel compounds, several showed superiority over the commercial fungicide Triadimefon against Cercospora arachidicola and Fusarium oxysporum f. sp. cucumerinum during this study. Meanwhile, some compounds displayed plant growth regulatory activity at the dosage of 10 μg/mL.