Efficient Synthesis of Novel 3‐Phenyl‐5‐thioxo‐3,4,5,6‐tetrahydroimidazo[4,5‐c]pyrazole‐2(1H)‐carbothioamide Derivatives Using a CeO2–MgO Catalyst and Evaluation of Antimicrobial Activity

Imidazo[4,5‐c ]pyrazole derivatives ( 3a–f , 4a–f , and 5a–f ) were efficiently synthesized by one‐pot three‐component reactions using CeO₂–MgO as the catalyst. The synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. The in vitro antimicrobial activity of the synthesized compounds against various bacterial and fungal strains was screened. Compound 3b was highly active [minimum inhibitory concentration (MIC): 0.5 μg/mL] against Gram‐positive Staphylococcus aureus , and compounds 3b , 3f , 4d , and 4e were highly active (MIC: 0.5, 2, 2, and 0.5 μg/mL, respectively) against Gram‐negative Pseudomonas aeruginosa and Klebsiella pneumoniae , relative to standard ciprofloxacin in the antibacterial activity screening. Compounds 3b and 4f were highly active (MIC: 4 and 0.5 μg/mL, respectively) against Aspergillus fumigatus and Microsporum audouinii in the antifungal activity screening compared with the clotrimazole standard.     

Synthesis,Antimicrobial, and Antioxidant Screening of Aryl Acetic Acid Incorporated 1,2,4‐Triazolo‐1,3,4‐Thiadiazole Derivatives

Some novel [1,2,4]triazolo[3,4‐b][1,3,4]thiadiazole derivatives were synthesized from aryl acetic acids. All the synthesized derivatives were selected for the screening of antibacterial potential against Gram‐positive bacteria [Staphylococcus aureus (MTCC 3160) and Micrococcus luteus (MTCC 1538)] and Gram‐negative bacteria [Escherichia coli (MTCC 1652) and Pseudomonas aeruginosa (MTCC 424)] and antifungal potential against Aspergillus niger (MTCC 8652) and Candida albicans (MTCC 227), and free radical scavenging activity through 2,2‐diphenyl‐2‐picrylhydrazyl hydrate method. The compounds TH‐4 , TH‐13 , and TH‐19 were found to be more potent antimicrobial agents compared to standard drugs. The compounds TH‐3 , TH‐9 , and TH‐18 also showed significant antimicrobial activity. The compound TH‐13 showed antioxidant activity with IC₅₀ value better than the standard compound. The structures of all the synthesized compounds were confirmed by Fourier transform infrared, ¹H‐NMR, liquid chromatography–mass spectrometry, and CHN analyzer.     

Synthesis and Antimicrobial Screening of Some Novel 2‐(5‐(4‐(1H‐Benzo[d][1,2,3]triazol‐1‐yl)phenyl)‐4,5‐dihydro‐1H‐pyrazol‐3‐yl)phenols Incorporated by Triazole Moiety

A novel series of 2‐(5‐(4‐(1H‐benzo[d][1,2,3]triazol‐1‐yl)phenyl)‐4,5‐dihydro‐1H‐pyrazol‐3‐yl)phenols derivative has been synthesized from (E)‐3‐(4‐(1H‐benzo[d][1,2,3]triazol‐1‐yl)phenyl)‐1‐(2‐hydroxyphenyl)prop‐2‐en‐1‐ones in ethanol and hydrazine hydrate under reflux condition. The synthesized compounds were screened for antibacterial activity against Gram‐positive bacteria viz Staphylococcus aureus and Bacillus subtilis and Gram‐negative bacteria viz Escherichia coli and Salmonella typhi, respectively. Some of the tested compounds showed significant antimicrobial activity. IR, ¹H NMR, mass spectral data, and elemental analysis elucidated the structures of all the newly synthesized compounds.     

Sulfonamide‐derived compounds and their transition metal complexes: synthesis,biological evaluation and X‐ray structure of 4‐bromo‐2‐[(E)‐{4‐[(3,4‐dimethylisoxazol‐5 yl)sulfamoyl]phenyl} iminiomethyl] phenolate

Sulfonamide‐derived new ligands, 4‐({[(E)‐(5‐bromo‐2‐hydroxyphenyl)methylidene]‐amino}methyl)benzenesulfonamide and 4‐bromo‐2‐((E)‐{4‐[(3,4‐dimethylisoxazol‐5‐yl)sulfamoyl]phenyl}iminiomethyl)phenolate and their transition metal [cobalt(II), copper(II), nickel(II) and zinc(II)] complexes were synthesized and characterized. The nature of bonding and structure of all the synthesized compounds were deduced from physical (magnetic susceptibility and conductivity measurements), spectral (IR, ¹H and ¹³C NMR, electronic, mass spectrometry) and analytical (CHN analysis) data. The structure of the ligand, 4‐bromo‐2‐((E)‐{4‐[(3,4‐dimethylisoxazol‐5‐yl)sulfamoyl]phenyl} iminiomethyl)phenolate was also determined by X‐ray diffraction method. An octahedral geometry was suggested for all the complexes. In order to evaluate the biological activity of the ligands and the effect of metals, the ligands and their metal complexes were screened for in vitro antibacterial, antifungal and cytotoxic activity. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against various fungal strains. Copyright © 2011 John Wiley & Sons, Ltd.     

An Efficient Synthesis and Antibacterial Activity of Pyrido[2,3‐d]Pyrimidine,Chromeno[3,4‐c]Pyridine,Pyridine, Pyrimido[2,3‐c]Pyridazine,Enediamines, and Pyridazine Derivatives

A series of Pyrido[2,3‐d]pyrimidine have been synthesized through a reaction of cyanoacetylurea derivatives with aromatic aldehydes or Arylidines. Reaction of compound 1 with aromatic arylidine derivatives or arylhydrazones gave Chromeno[3,4‐c]pyridine, Pyridine, Pyrimido[2,3‐c]pyridazine, Enediamines, and Pyridazine derivatives. All the synthesized compounds were confirmed by spectral studies and screened for their in antibacterial activity against Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative) bacterial strains. All the compounds were weak to good active against the tested bacterial strains on comparing with the standard drug gentamicin.     

Synthesis and Antimicrobial Evaluations of Some Novel Mono‐, Bis‐, and Tris‐Nitro‐1,2,4‐Triazines

Substituted‐1,2,4‐triazines were conveniently synthesized in one pot by the cyclization of arylnitroformaldehyde hydrazone derivatives 1 and 5 with different primary amines in ~37% formaldehyde solution. The synthesized compounds were arranged into novel mono‐, bis‐, and tris‐nitro‐1,2,4‐triazine derivatives 2 , 3 , 4 , 6 , and 7 . The antibacterial and antifungal activity of the synthesized compounds were screened against bacterial strains Escherichia coli (as Gram − ve) and Staphylococcus aureus (as Gram + ve), and fungal strains Aspergillus flavus and Candida albicans . All the synthesized compounds exhibit various patterns of inhibitory activity on the two pathogenic bacterial strains. However, the same compounds showed no activity against the tested fungal strains.     

Synthesis of Some 3‐(4‐Aryl‐benzofuro[3,2‐b]pyridin‐2‐yl)coumarins and Their Antimicrobial Screening

The synthesis of some 3‐(4‐aryl‐benzofuro[3,2‐b]pyridin‐2‐yl)coumarins 3a–r has been carried out by the reaction of 3‐coumarinoyl methyl pyridinium salts 1a–c with 2‐arylidene aurones 2a–f in the presence of ammonium acetate and acetic acid under Kröhnke's reaction conditions. All the synthesized compounds were characterized by analytical and spectral data. They have been screened for their antibacterial activity against Escherichia coli (ATCC 25922) as Gram‐negative bacteria, Bacillus subtillis (ATCC 1633) as Gram‐positive bacteria and antifungal activity against Aspergillus niger (ATCC 9029).     

Synthesis and Antimicrobial Activity of Some New N‐substituted‐5‐arylidene‐thiazolidine‐2,4‐diones

A total of 17 new N‐substituted derivatives ( 2b , 2c , 2d , 2e , 2f , 2g , 2h , 2i , 2j , 2k and 3b , 3c , 3d , 3e , 3f , 3g , 3h ) of 5‐((2‐phenylthiazol‐4‐yl)methylene) thiazolidine‐2,4‐dione ( 2a ) and 5‐(2,6‐dichloro‐ benzylidene)thiazolidine‐2,4‐dione ( 3a ) were synthesized. The structural elucidation of the newly synthesized compounds was based on elemental analysis and spectroscopic data (MS, ¹H NMR, ¹³C NMR), and their antimicrobial activities were assessed in vitro against several strains of Gram‐positive and Gram‐negative bacteria and one fungal strain (Candida albicans) as growth inhibition diameter. Some of them showed modest to good antibacterial activity against Gram‐negative Escherichia coli and Salmonella typhimurium and Gram‐positive Staphylococcus aureus, Bacillus cereus, and Enterococcus fecalis bacterial strains, whereas almost all the compounds were inactive against Listeria monocytogenes. All of the synthesized compounds showed moderate to very good activity against C. albicans.     

Synthesis and Antimicrobial Evaluation of Some New 4,5′‐Bisthiazoles

Thiazole and bisthiazole derivatives represent a prevalent scaffold in the antimicrobial drug discovery. Therefore, we have decided to synthesize some new series of 4,5′‐bisthiazoles. A total of 17 compounds were synthesized, their structural elucidation being based on elemental analysis (C,H,N,S) and spectroscopic data (MS and ¹H NMR). Their in vitro antimicrobial activities were assessed against several Gram‐positive and Gram‐negative bacteria strains and also against one fungal strain (Candida albicans) using the difusimetric method. Some of the compounds showed modest to good antibacterial activity against Gram‐negative Escherichia coli and Salmonella typhimurium and Gram‐positive Staphylococcus aureus and Bacillus cereus bacterial strains. All of the synthesized compounds showed moderate to very good antifungal activity against C. albicans.     

Synthesis and Antimicrobial Activity of N‐[(2Z)‐3‐(4,6‐Substitutedpyrimidin‐2‐yl)‐4‐phenyl‐1,3‐thiazol‐2(3H)‐ylidene]‐3, 5‐dinitrobenzamide Analogues

In this study, we have synthesized 1‐(4,6‐disubstitutedpyrimidin‐2‐yl)‐3‐(3,5‐dinitrobenzoyl)‐thiourea derivatives ( 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h ) and N‐[(2Z)‐3‐(4,6‐disubstitutedpyrimidin‐2‐yl)‐4‐phenyl‐1,3‐thiazol‐2(3H)‐ylidene]‐3, 5‐dinitrobenzamide ( 2a‐2h ) analogues and characterized by IR spectroscopy, NMR spectroscopy, elemental analysis, and single crystal X‐ray diffraction data. The compounds ( 2a‐2h ) were screened for antimicrobial activity against Gram positive, Gram negative, and fungal species. The results of antimicrobial study indicated that compounds showed most potential and appreciable antibacterial and antifungal activities.     

Synthesis and Evaluation of Novel 5‐cyclohexyl‐2‐(4″‐substitutedphenyl)‐3‐(2″‐substitutedphenyl)4H‐2,3,3a,5,6,6a‐hexahydropyrrolo[3,4‐d]isoxazole‐4,6‐dione Derivatives for Their In Vitro Antioxidant and Antibacterial Activities

1,3‐Dipolar cycloaddition reactions of N‐cyclohexyl maleimide ( 1 ) with azomethine N‐oxide ( 2 ) have afforded novel isoxazolidine ( 3 ) in excellent yield. Their structures have been characterized from their IR, ¹H‐NMR, ¹³C‐NMR, ¹H,¹H‐COSY, MS(ESI), and elemental analysis techniques. In vitro antibacterial activity of the synthesized compounds were investigated against a representative panel of pathogenic strains specifically two Gram‐positive bacteria (Staphylococcus aureus and Streptococcus pyogenes ) and two Gram‐negative bacteria (Pseudomonas aeruginosa and Escherichia coli ) using agar‐well diffusion assay. Some of the compounds ( 3a , 3k , 3n , and 3o ) exhibited promising antibacterial activities. All the synthesized compounds have also been screened for their antioxidant activities and were found to be significantly active.     

Synthesis and Antimicrobial Activity of Some Novel [4‐(1,2,3‐thiadiazol‐4‐yl)phenoxy]methylene anchored 1,3,4‐triazoles and 1,3,4‐thiadiazoles

A series of novel [4‐(1,2,3‐thiadiazol‐4‐yl)phenoxy]methylene anchored 1,3,4‐triazoles ( 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h ) and 1,3,4‐thiadiazoles ( 9a , 9b , 9c , 9d , 9e , 9f , 9g , 9h , 9i ) were synthesized from thiosemicarbazide ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j ). The structures of these newly synthesized compounds were confirmed on the basis of IR, ¹H‐NMR, mass spectral techniques, and elemental analysis. The in vitro antimicrobial screenings of the synthesized compounds were carried out against four bacterial pathogens, namely Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa and three fungal pathogens Candida albicans, Aspergillus niger and Aspergillus clavatus, using broth microdilution minimum inhibitory concentration method. The compounds 7d , 7j , 8a , 9a , 9b , and 9i exhibited promising antibacterial activity against the tested strains, whereas some compounds were found to be active against one of the tested bacterial strains.     

Organoiodine(III) Mediated Synthesis of Novel Symmetrical Bis([1,2,4]triazolo)[3,4‐a:4′,3′‐c]phthalazines as Antibacterial and Antifungal Agents

A series of new symmetrical 3,6‐bis(aryl)bis([1,2,4]triazolo)[3,4‐a:4′,3′‐c]phthalazines 9a‐l has been conveniently synthesized by oxidative cyclization of 1,4‐bis(substituted benzalhydrazino)phthalazines 8a‐l promoted by iodobenzene diacetate under mild conditions (12 examples, up to 93% yield). All the 12 compounds were tested in vitro for their antibacterial activity against two Gram‐positive bacteria, namely, Staphylococcus aureus, Bacillus subtilis and two Gram‐negative bacteria, namely, Escherichia coli and Pseudomonas aeruginosa. All the synthesized compounds were also tested for their antifungal action against two fungi, Aspergillus niger and Aspergillus flavus.     

Synthesis and antimicrobial activity of some 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones

The title compounds, 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been synthesized by reacting various 4‐hydroxy coumarins 1a , 1b , 1c with 2‐arylidene‐1‐tetralones 2a , 2b , 2c , 2d in the presence of ammonium acetate and acetic acid under Krohnke's reaction condition. The structures of all the synthesized compounds were supported by analytical, IR, ¹H‐NMR, and ¹³C‐NMR data. All the synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been screened for their antibacterial activities against Escherichia coli (Gram ?ve bacteria), Bacillus subtilis (Gram +ve bacteria), and antifungal activity against Candida albicans (Fungi). J. Heterocyclic Chem., (2011).     

Synthesis,Antibacterial Activity,and Docking Studies of 1,2,3‐triazole‐tagged Thieno[2,3‐d]pyrimidinone Derivatives

Novel (1‐(substituted phenyl)‐1H ‐1,2,3‐triazol‐4‐yl)methyl‐2‐(4‐oxo‐5,6,7,8‐tetrahydrobenzo[1,2]thieno[2,3‐d ]pyrimidin‐3(4H )‐yl)acetate derivatives were synthesized. All the compounds showed significant antibacterial activity against Gram‐negative (Escherichia coli and Klebsiella pneumonia ) and Gram‐positive (Bacillus subtilis and Bacillus cereus ) bacteria. Particularly, (1‐(3‐nitrophenyl)‐1H ‐1,2,3‐triazol‐4‐yl)methyl‐2‐(4‐oxo‐5,6,7,8‐tetrahydrobenzo[1, 2]thieno[2,3‐d ]pyrimidin‐3(4H )‐yl)acetate was found to be most potent against E. coli , K. pneumonia , and B. subtilis with MIC 25 μg/ml. Molecular docking was also performed on purine riboswitch of B. subtilis and thiamine pyrophosphate riboswitch of E. coli .      

Synthesis of 3‐(substituted)‐2,4,8,15‐tetroxa‐3‐phosphadispiro[5.2.5]hexadecane‐3‐oxides

Novel 3‐(substituted)‐2,4,8,15‐tetroxa‐3‐phosphadispiro[5.2.5]hexadecane‐3‐oxides (3‐12) have been synthesized by cyclization of 1,5‐dioxaspiro[5.5]undecande‐3,3‐dimethanol (1) with various substituted aryl phosphorus dichloridates (2) in dry toluene‐THF in the presence of triethylamine at 40‐60 ^oC. Their molecular structures were determined by ir, nmr and mass spectral studies and were screened for antifungal activity against Curvularia lunata and Aspergillus niger, and antibacterial activity on Staphylococcus aureus and Escherichia coli. Most of them possess significant activity.     

Metal‐based sulfonamides: synthesis,characterization, antibacterial,antifungal and cytotoxic properties of pyrrolyl‐ and thienyl‐derived compounds

Pyrrolyl and thienyl derived sulfonamides and their metal [cobalt(II), copper(II), nickel(II) and zinc(II)] complexes were synthesized and characterized by elemental analyses, molar conductances, magnetic moments, IR, ¹H NMR, ¹³C NMR and electronic spectral data. These compounds were screened for in‐vitro antibacterial activity against four Gram‐negative (Escherichia coli, Shigella flexeneri, Pseudomonas aeruginosa and Salmonella typhi) and two Gram‐positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains, and for in‐vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies revealed that all compounds showed significant to moderate antibacterial activity; however, the zinc complexes were shown to be the most active against various species. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties of all the synthesized ligands and their metal complexes. Only two compounds ( 14 and 19 ) displayed potent cytotoxic activity as LD₅₀ = 5.5637 × 10^?4 and 4.4023 × 10^?4 M ml^?1 respectively, against Artemia salina. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and Antimicrobial Activity of Novel Derivatives of 7‐aryl‐10‐thioxo‐7, 10, 11, 12 – tertahydro‐9H‐benzo[H] pyrimido [4,5‐b] quinoline‐8‐one

A highly competent synthesis of novel 7‐aryl‐10‐thioxo‐7, 10, 11, 12‐tertahydro‐9H‐benzo [H] pyrimido [4, 5‐b] quinoline‐8‐one derivatives has been reported through a Knoevenagel condensation followed by Michael addition and subsequent cyclization using ethanol:acetic acid (8:2 v/v). The mentioned protocol has advantages like high yields, cleaner reactions, operational simplicity, and environment friendliness. Moreover, these compounds were further screened against the plant pathogenic fungi like Colletotrichum truncatum, Ustilago maydis, Trichosporon, Trichothecium sp., Aspergillus oryze, Aspergillus terreus, and Aspergillus niger by agar well method bioassay. The results were elaborated for minimum inhibitory concentration determination using agar dilution method against fungal strains C. truncatum and U. maydis as well as broth dilution method for bacteria species Gram‐positive Bacillus megaterium and Gram‐negative Proteus vulgaris. Most of the tested compounds showed promising results towards the antimicrobial activity.     

Synthesis and antimicrobial activity of novel 2‐(aryl)‐3‐[5‐(2‐oxo‐2H‐3‐chromenyl)‐1,3‐oxazol‐2‐yl]‐1,3‐thiazolan‐4‐ones

A series of novel 2‐(aryl)‐3‐[5‐(2‐oxo‐2H‐3‐chromenyl)‐1,3‐oxazol‐2‐yl]‐1,3‐thiazolan‐4‐ones 4a , 4b , 4c , 4e , 4f , 4g , 4h , 4i , 4j have been synthesized and assayed for their antibacterial activity against Gram‐positive bacteria viz. Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538p), Micrococcus luteus (IFC 12708), and Gram‐negative bacteria viz. Proteus vulgaris (ATCC 3851), Salmonella typhimurium (ATCC 14028), Escherichia coli (ATCC 25922), and also antifungal activity against Candida albicans (ATCC 10231), Aspergillus fumigatus (HIC 6094), Trichophyton rubrum (IFO 9185), and Trichophyton mentagrophytes (IFO 40996). Among the screened compounds, 4d , 4e , 4f , 4g , and 4j exhibited potent inhibitory activity compared with the standard drug at the tested concentrations. The results reveal that, the presence of difluorophenyl in 4f and pipernyl ring in 4j at 2‐position of thiazolidine‐4‐one ring show significant inhibitory activity. The other compounds also showed appreciable activity against the test bacteria and fungi and emerged as potential molecules for further development. J. Heterocyclic Chem., 2011.     

A facile synthesis and antimicrobial activity of 2,10‐dichloro‐6‐(aryloxy/thiophenoxy)‐4,8‐dinitrodibenzol[d,g][1,3,6,2]‐dioxathiaphosphocin‐ 6‐oxides

Novel 6‐substituted 2,10‐dichloro‐4,8‐dinitrodibenzo[d,g][1,3,6,2]dioxathiaphosphocin‐6‐oxides 4 were synthesized by reacting 5,5′‐dichloro‐3,3′‐dinitro‐2,2′‐dihydroxydiphenyl sulfide ( 2 ) with different aryl phosphorodichloridates, trichloromethylphosphonic dichloride and O‐2‐chloroethyl phosphoryldichloride (3) in the presence of triethylamine at 55–60°. Some of these compounds are prepared by reacting the monochloride, 2,6,10‐trichloro‐4,8‐dinitrodibenzo[d,g][1,3,6,2]dioxathiaphosphoein‐6‐oxide ( 5 ) in situ with substituted phenols and thiols. 5 is prepared by condensing 2 with phosphorus oxychloride. The ¹H nmr chemical shifts of the dibenzodioxathiaphosphocin moiety indicates the presence of more than one conformer in solution. However the presence of more than one conformer in each example cannot be entirely eliminated. Interestingly 4d on oxidation to 12‐sulphone by H₂O₂ in acetic acid medium yielded only 12‐sulphoxide 6a . The ir, ¹H, ¹³C, ³¹P nmr and mass spectral data are discussed. Some of these compounds were screened for antifungal activity against Curvularia lunata and Aspergillus niger and antibacterial activity on Bacillus subtilis and Klebsiella pneumoniae. A few of them possess significant activity.