Deyu Hu

Synthesis and Antiviral Activities of Pyrazole Derivatives Containing an Oxime Moiety

Target compounds 4a- n were obtained by the reaction of 1-substituted phenyl-3-methyl-5-substituted phenylthio-4-pyrazolaldoximes (3) with chloromethylated heterocyclic compounds (ClCH 2-R 3) under reflux conditions in ethanol. Subsequently, the oxidation of 4a- e with KMnO 4 in HOAc at room temperature afforded eight new compounds, 5a- h. The synthesized compounds were characterized by physical constants, and the structures of the title compounds were confirmed by IR, (1)H NMR, (13)C NMR, and elemental analysis. The bioassay revealed that the compounds possessed antiviral activities. It was found that title compounds 4a and 4g had the same inactivation effects against TMV (EC 50 = 58.7 and 65.3 microg/mL) as the commercial product Ningnanmycin (EC 50 = 52.7 microg/mL). To the best of our knowledge, this is the first report on the antiviral activity of pyrazole derivatives containing an oxime moiety.

Synthesis and antifungal activity of novel sulfoxide derivatives containing trimethoxyphenyl substituted 1,3,4-thiadiazole and 1,3,4-oxadiazole moiety

Selective oxidation of sulfides 7 or 8 to sulfoxides 9 or 10 is achieved by mCPBA. The structures of the compounds 9 or 10 are confirmed by elemental analysis, IR, and (1)H NMR. The bioassay results showed that title compound 10a possess high antifungal activities with EC(50) values ranging from 19.91 to 63.97 microg/mL. The mechanism of action of 10a against Sclerotinia sclerotiorum was studied. After treating with compound 10a at 100 microg/mL for 12 h, the mycelial reducing sugar, D-GlcNAc, soluble protein and pyruvate content, chitinase activity showed declining tendency.

Synthesis and Antiviral Activities of Chiral Thiourea Derivatives Containing an α-Aminophosphonate Moiety

Starting from benzaldehyde 1, the title compounds 8 were synthesized in six steps. Benzaldehyde 1 was reacted with ammonium hydroxide, and the resulting imine was then treated with dialkyl phosphite 3 to give dialkyl N-(arylmethylene)-1-amino-1-aryl methylphosphonates 4. Phosphonates 4 were then easily hydrolyzed to give dialkyl 1-amino-1-aryl-methylphosphonates 6, which on treatment with triethylamine, carbon disulfide, and phosphorus oxychloride provided 7. Target compounds 8 were then prepared by the reaction of 7 with substituted chiral amine. The structures were clearly verified by spectroscopic data (IR, (1)H, (13)C, and (31)P NMR, and elemental analysis). The bioassay of these compounds revealed them as antivirally active. It was found that title compounds 8g, 8e, 8k, and 8m had the same curative effects of TMV (inhibitory rate = 54.8, 50.5, 50.4, and 50.4%, respectively) as the commercial product Ningnanmycin (56.2%). This would appear to be the first report of the synthesis and antiviral activity of chiral thiourea derivatives containing an alpha-aminophosphonate moiety.

Synthesis and Antiviral Activities of Amide Derivatives Containing the α-Aminophosphonate Moiety

Starting from (substituted-)benzaldehydes, the title compounds 6 were synthesized through five step reactions. Benzaldehydes were treated with ammonium hydroxide, followed by dialkyl phosphite, to give dialkyl N-(arylmethylene)-1-amino-1-aryl methylphosphonates ( 3). Phosphonates 3 were then easily hydrolyzed to give dialkyl 1-amino-1-aryl-methylphosphonates 5. Target compounds 6 were then obtained by the reaction of 5 and substituted benzoic or cinnamic acid. Their structures were clearly verified by spectroscopic data (IR, 1H, 13C, and 31P NMR, and elemental analysis). These compounds were shown to be antivirally active in the bioassay. It was found that title compounds 6g, 6l, and 6n had the same inactivation effect of TMV (EC 50 = 54.8, 60.0, and 65.2 microg/mL, respectively) as commercial product Ningnanmycin (EC50 = 55.6 microg/mL). To the best of our knowledge, this is the first report on the synthesis and antiviral activity of amide derivatives containing an alpha-aminophosphonate moiety.

Synthesis and antiviral activity of novel pyrazole derivatives containing oxime esters group

Fourteen title compounds, 1-substituted-5-substitutedphenylthio-4-pyrazolaldoxime ester derivatives 4a-4n, were synthesized from the starting material 1-substitutedphenyl-3-methyl-5-substitutedphenylthio-4-pyrazolaldoximes 3 by treatment with acyl chloride. The synthesized compounds were characterized by physical constants, and the structures of the title compounds were further confirmed by IR, 1H NMR, 13C NMR and elemental analysis. The bioassay results showed that title compounds possessed weak to good anti-TMV bioactivity with 4l showing significant enhancement of disease resistance in tobacco leaves with high affinity for TMV CP.

Design, synthesis and insecticidal activities of novel pyrazole amides containing hydrazone substructures

BACKGROUND Pyrazole and hydrazone derivatives possess good insecticidal activities; their substructural units are widely used in pesticide design. In an effort to discover new molecules with good insecticidal activities, a series of pyrazole amide derivatives containing hydrazone substructures were synthesised and bioassayed. RESULTS Bioassays demonstrated that some of the title compounds exhibited notable control of Plutella xylostella (Linnaeus), Helicoverpa armigera (Hübner), Culex pipiens pallens, Laphygma exigua (Hübner), Spodoptera litura (Fabricius), Nilaparvata lugens (Stål) and Rhopalosiphum maidis (Fitch) at 5, 10, 0.25, 200, 20, 100 and 500 mg L(-1) respectively. Comparative molecular field analysis (CoMFA) based on the bioactivities for P. xylostella was studied; the values of q(2) and r(2) for the CoMFA model were 0.701 and 0.964 respectively. CONCLUSION Some of the title compounds displayed good and broad-spectrum insecticidal activities against different insect species; the CoMFA model revealed that a bulky and negatively charged group at the 4-position of benzene could enhance insecticidal activity. These results could provide useful information for the design of novel insecticide containing substructural units of pyrazole amide and hydrazone.

Design, synthesis, and antibacterial activity against rice bacterial leaf blight and leaf streak of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivative.

A series of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivatives were synthesized and evaluated for their antibacterial activities against rice bacterial leaf blight and leaf streak caused by Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicolaby via the turbidimeter test in vitro. Antibacterial bioassay results indicated that most compounds demonstrated good inhibitory effect antibacterial bioactivities against rice bacterial leaf blight and leaf streak. Among the title compounds, compound 6c demonstrated the best inhibitory effect against rice bacterial leaf blight and leaf streak with half-maximal effective concentration (EC50) values of 1.07 and 7.14 μg/mL, respectively, which were even better than those of commercial agents such as Bismerthiazol and Thiediazole Copper. In vivo antibacterial activities tests at greenhouse conditions demonstrated that the controlling effect of compounds 6c (43.5%) and 6g (42.4%) against rice bacterial leaf blight were better than those of Bismerthiazol (25.5%) and Thiediazole Copper (37.5%).

Synthesis and antiviral activity of 5-(4-chlorophenyl)-1,3,4- thiadiazole sulfonamides.

Starting from 4-chlorobenzoic acid, 10 new 5-(4-chlorophenyl)-N-substituted-N-1,3,4-thiadiazole-2-sulfonamide derivatives were synthesized in six-steps. Esterification of 4-chlorobenzoic acid with methanol and subsequent hydrazination, salt formation and cyclization afforded 5-(4-chlorophen-yl)-1,3,4-thiadiazole-2-thiol (5). Conversion of this intermediate into sulfonyl chloride 6, followed by nucleophilic attack of the amines gave the title sulfonamides 7a-7j whose structures were confirmed by NMR, IR and elemental analysis. The bioassay tests showed that compounds 7b and 7i possessed certain anti-tobacco mosaic virus activity.

Synthesis and Antiviral Activities of Cyanoacrylate Derivatives Containing an α-Aminophosphonate Moiety

Target compounds 8 were obtained by the reaction of alkyl 2-cyano-3,3-dimethylthioacrylate or cyarylamide (7a-7e) and alpha-aminobenzylphosphonate (5a-5e) under reflux condition using ethanol as solvent. Their structures were clearly verified by spectroscopic data (IR and 1H, 13C, and 31P NMR) and elemental analysis. These compounds were shown to be antivirally active in the bioassay. It was found that title compounds 8d and 8e had the same inactivation effect against tobacco mosaic virus (EC 50 = 55.5 and 55.3 microg/mL) as the commercial product ningnanmycin (EC 50 = 50.9 microg/mL). To the best of our knowledge, this is the first report on the synthesis and antiviral activity of cyanoacrylate derivatives containing an alpha-aminophosphonate moiety.

Antibacterial activities against rice bacterial leaf blight and tomato bacterial wilt of 2-mercapto-5-substituted-1,3,4-oxadiazole/thiadiazole derivatives

In this study, a series of 2-mercapto-5-substituted-1,3,4-oxadiazole/thiadiazole derivatives were synthesized and evaluated for their antibacterial activities against rice bacterial leaf blight and tomato bacterial wilt caused by Xanthomonas oryzae pv. oryzae (Xoo) and Ralstonia solanacearum (R. solanacearum) via the turbidimeter test in vitro. Antibacterial bioassays indicated that most compounds demonstrated appreciable antibacterial bioactivities against Xoo and R. solanacearum. Among the title compounds, compound 4i demonstrated the best inhibitory effect against Xoo and R. solanacearum with half-maximal effective concentration (EC50) values of 14.69 and 15.14μg/mL, respectively, which were even better than those of commercial agents Bismerthiazol and Thiodiazole Copper. In vivo antibacterial activities tests under greenhouse conditions revealed that the control efficiency of compound 4i against rice bacterial leaf blight and tobacco bacterial wilt were better than those of Bismerthiazol and Thiodiazole Copper. Meanwhile, field trials also indicated that compound 4i demonstrated appreciable control efficiency against rice bacterial leaf blight and tomato bacterial wilt.