Synthesis,studies and in vitro antibacterial activity of some 5-(thiophene-2-yl)-phenyl pyrazoline derivatives

In the present investigation, a novel series of pyrazolines 2a–2d were synthesized by the cyclization of various -1-[2-(alkoxy) phenyl]-3-(thiophen-2-yl) prop-2-en-1-one 1a–1d with N-substituted phenyl hydrazine and thiosemicarbazide in the presence of CH₃COOH and NaOH in ethanol which lead to the formation of new pyrazolines. The structures of these compounds were elucidated by, IR, ¹H-NMR, ¹³C-NMR, ESI-MS spectral data and their purities were confirmed by elemental analyes. The in vitro antibacterial activity of these compounds was evaluated against two Gram-positive and two Gram-negative bacteria Aeromonas hydrophila, Yersinia enterocolitica, Listeria monocytogenes, and Staphylococcus aureus by microdilution method and then the minimum inhibitory concentration (MIC) of these compounds was determined. The results showed that compounds 1-[2-(benzyloxy) phenyl]-5-(thiophen-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl (2b) and 1-[2-(naphthalen-2-ylmethoxy) phenyl]-5-(thiophene-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole-4-yl (2d) showed most promising antibacterial activity as compared to the antibiotics gentamicin and tetracycline in (Table 1, Table 2).     

新型薁类-1-酰腙化合物的合成及抗菌活性研究

为了合成和研究具有薁类结构物质的新的生物活性, 以1-薁类羧酸甲酯为起始原料, 经过酰肼化、与芳香醛及酮类化合物的缩合, 合成了含有酰腙类结构的薁类衍生物, 其结构经1H NMR, IR和元素分析确证. 对所得化合物进行了抗菌活性测试, 初步表明它们具有一定的活性.     

Synthesis and Antibacterial Activity of s‐Triazoles,s‐Triazolo[3,4‐b]‐1,3,4‐thiadiazines and s‐Triazolo[3,4‐b]‐1,3,4‐thiadiazoles of 5‐Methylisoxazole

The condensation of 4‐amino‐5‐mercapto‐3‐(5‐methylisoxazol‐3‐yl)‐1,2,4‐triazole with substituted phenacyl bromide, aldehydes, p‐bromophenylisothiocyanate, aromatic carboxylic acids and oxalic acid, is described. The antibacterial activity of representative compounds was evaluated.     

Facile Microwave‐assisted Synthesis of 1,3,5‐Trisubstituted Pyrazoline Derivatives Incorporating Sulfonyl Moiety

We developed an environmentally benign, convenient microwave‐assisted process for the construction of 1,3,5‐trisubstitued pyrazolines ( 10a ～ 10f , 11a ～ 11f , 12a ～ 12f , 13a ～ 13f ). Chalcones, as the key intermedi‐ ates, were obtained by the condensation of each of appropriately substituted aromatic aldehydes ( 1 ～ 4 ) with 4‐substituted acetophenones ( 5a ～ 5f ) via a Claisen‐Schmidt reaction under the action of microwave irradiation. Cyclization of the chalcones ( 6a ～ 6f , 7a ～ 7f , 8a ～ 8f , 9a ～ 9f ) with p‐toluene sulfonhydrazide af‐ forded 1,3,5‐trisubstitued pyrazoline derivatives using microwave‐assisted process in 25 min and 140 watt power in glycol. The structures of targeted compounds were established by IR, ¹H NMR, MS and ele‐ mental analysis. The results indicate that microwave‐assisted synthetic process presents advantages in terms of enhancement in rate, decrease in reaction time, clean reaction and convenient operation.     

Antimicrobial Activity of Some Novel Thiourea,Hydrazine, Fused Pyrimidine and 2‐(4‐Substituted)anilinobenzoazole Derivatives Containing Sulfonamido Moieties

Thiophosgenation of sulfonamides 1a‐c in the presence of dilute HCl at room temperature furnished the isothiocyanatosulfonamides 2a‐c and treatment with aromatic amines gave 1,3‐disubstituted thioureas 3a,b . Also, interaction of two molecules of 2c with 1,4‐phenylenediamine yielded the novel bisthiourea 4 . Cyclocondensation of 2 with ortho amino carboxylic acid compounds such as anthranilic acids 8 , 5‐amino‐1‐phenyl‐pyrazol‐4‐carboxylic acid 9 and 4,5,6,7‐tetrahydro‐2‐amino‐benzo[b]thiophene‐3‐carboxylic acid 10 furnished the fused thiopyrimidines 11a‐d, 12 and 13 , respectively. 2‐Anilinobenzoazole derivatives 15a‐c, 16a, b and 17a,b were obtained through cyclocondensation of 2 with 1,2‐dinucleophiles.     

Mild Oxidation of 1,3,5‐Trisubstituted Pyrazolines with N‐Bromo‐sulphonamides

1,3,5‐Trisubstituted pyrazolines to pyrazoles are carried out efficiently in the presence of new reagents N,N,N′, N′‐tetrabromo‐benzene‐1,3‐disulfonylamine [TBBDA] and N,N′‐dibromo‐N,N′‐1,2‐ethanediylbis‐(p‐toluenesulphonamide) [BNBTS] in solvent‐free conditions with catalytic amounts of SiO₂ under microwave irradiation in high yields.     

Hybrid 4‐Aminoquinoline‐1,3,5‐triazine Derivatives: Design,Synthesis, Characterization,and Antibacterial Evaluation

A series of novel 4‐aminoquinoline 1,3,5‐triazine derivatives were synthesized and characterized by FTIR, ¹H‐NMR, ¹³C‐NMR, MS, and elemental analysis. The antibacterial activities of synthesized compounds were tested against three Gram‐positive bacteria, namely Bacillus subtilis (NCIM‐2063), Bacillus cereus (NCIM‐2156), and Staphylococcus aureus (NCIM‐2079), and four Gram‐negative bacteria, namely Proteus vulgaris (NCIM‐2027), Proteus mirabilis (NCIM‐2241), Escherichia coli (NCIM‐2065), and Pseudomonas aeruginosa (NCIM‐2036), using ciprofloxacin as reference standard drug. Results showed compound 9a and 9e as potent antibacterial agents against all bacterial strains except Bacillus cereus (NCIM‐2156). Copyright © 2014 HeteroCorporation     

Synthesis and Antibacterial Activity of Some New 2,5‐Disubstituted‐1,3,4‐oxadiazole Derivatives

Synthesis of some new oxadiazole derivatives starting from 1,2,3-benzo[d]triazole-1-acetic hydrazide (1) is described. The target compounds 2-(N-substituted-aminocarbonylmethylthio)-5-(1,2,3-benzo[d]triazol-1-ylmethyl)- 1,3,4-oxadiazole (4a—4i) and 2-[2-(N-substituted-aminocarbonyl)ethylthio]-5-(1,2,3-benzo[d]triazol-1-ylmethyl)- 1,3,4-oxadiazole (5a—5i) were obtained in good yields via cyclisation of 1 and subjected to antibacterial activity test against pathogenic bacteria. The halogen containing mono- and di-substituted derivatives showed excellent antibacterial activity compared to other analogues.     

Design,Synthesis and Biological Activity of Novel Chalcone Derivatives as Anti-influenza Agents

A series of novel chalcone derivatives was designed and synthesized via a suitable synthetic strategy in good yields using commercially available 2-amino-4-nitrophenol as an initiator. The structures of the target compounds were confirmed by means of ¹H NMR, ¹³C NMR and high-resolution mass spectrometry(HRMS). And the ability of the target compounds to inhibit influenza viruses was evaluated. These compounds showed moderate inhibitory activity against influenza A(H9N2 and H5N1) viruses. Within this series, compounds S14 and S15 with good potency(IC₅₀=40.3-51.5μmol/L) could be used as lead compounds in the future.     

Synthesis of Novel 3‐Acetyl‐2‐Aryl‐5‐(3‐Aryl‐1‐Phenyl‐Pyrazol‐4‐yl)‐2,3‐Dihydro‐1,3,4‐Oxadiazoles

A series of novel pyrazolyl‐substituted 1,3,4‐oxadiazole derivatives ( 4a‐4o ) were prepared by cyclization of the intermediate N′‐((3‐aryl‐l‐phenyl‐pyrazol‐4‐yl)methylene)arylhydrazide with acetic anhydride. The structures of the new compounds were confirmed by IR, ¹H NMR, MS and elemental analysis. Furthermore, preliminary bioassay of some of the title compounds indicated that they exhibited moderate inhibition against HIV‐1 PR.     

Tricholoroisocyanuric Acid as a Useful Reagent in Microwave‐assisted Aromatization of 1,3,5‐Trisubstituted 2‐Pyrazolines

An efficient aromatization of 1,3,5‐trisubstituted 2‐pyrazolines to their corresponding pyrazoles has been performed by tricholoroisocyanuric acid [TCCA] under microwave irradiation in excellent yields. It has been observed that the reactions occur more rapidly under microwave irradiation conditions, and the amount of the reagent TCCA consumed is considerably reduced to afford better yields when compared with conventional thermal conditions at the same temperature.     

Synthesis and Biological Activity of a Series of Novel N‐Substituted β‐Lactams Derived from Natural Gallic Acid

A series of novel β‐lactams derived from natural gallic acid were conveniently synthesized via classical Staudinger ketene‐imine cycloaddition reaction. Their structures were confirmed by satisfactory analytical and spectroscopic methods. The preliminary bioassay showed that some of the target compounds exhibited obvious insecticidal activity against Heliothis armigera at the dosage of 0.2 mg/mL.     

Optical Activity 1,5‐Substituted‐1,3,5‐hexahydrotriazine‐2‐N‐nitroimines: Synthesis and Insecticidal Activity

Twelve novel neonicotinoid analogues 1‐(2‐furfuryl)‐5‐substituted‐1,3,5‐hexahydrotriazine‐2‐N‐nitroimines 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l were synthesized. Their structures were characterized by ¹H NMR, IR, and elemental analysis. The preliminary bioassay tests showed that all the title compounds gave ≥90% mortality against Nilaparvata lugen 500 mg/L.     

Synthesis and Antibacterial Evaluation of Some Semicarbazides and 1,2,4‐Triazol‐5‐Ones Containing Thiophene Moieties

In this study, some 3‐(thiophen‐2‐ylmethyl)‐4‐substituted‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐one derivatives were synthesized by the cyclization reaction of 1‐(thiophen‐2‐ylacetyl)‐4‐substituted semicarbazide derivatives in alkaline medium or in the immediate reaction of thiophen‐2‐yl‐acetic acid hydrazide with isocyanates. The structures of all new compounds were confirmed by analytical and spectroscopic methods. Selected derivatives were evaluated in vitro against several species of aerobic bacteria. Some of them showed activity against S. pyogenes, P. aeruginosa and S. aureus.