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.     

Synthesis and Antimicrobial Activities of Novel Series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one Derivatives

In the present investigation, a novel series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one derivatives were synthesized by condensation of 2‐substituted‐4‐methylthiazole‐5‐carbaldehyde with 4‐(2‐substituted thiazol‐4‐yl)benzenamine followed by cyclo‐condensation with thioglycolic acid in toluene. All the newly synthesized compounds were characterized by spectral (IR, ¹H NMR, ¹³C NMR, and Mass) methods. The title compounds were screened for quantitative antibacterial activity (minimal inhibitory concentration). All compounds 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h and 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h show moderate to good antimicrobial activity, whereas compounds ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h ) also show moderate antifungal activity.     

Synthesis and Antimicrobial Activity of 2‐(Pyridine‐3‐yl)‐4H‐chromen‐4‐one Derivatives

An efficiently synthesis of chromones via cyclodehydration of corresponding 1‐(2‐hydroxyphenyl)‐3‐(pyridine‐3‐yl)propane‐1,3‐dione is described under ultrasound irradiation. A series of novel 2‐(pyridine‐3‐yl)‐4H‐chromen‐4‐one derivatives was confirmed on the basis of ¹H‐NMR, mass, IR spectral data, and elemental analysis. The synthesized compounds were evaluated for their antibacterial and antifungal activities. Most of the compounds were found to be comparable potent than the reference standard drugs. Utilization of ultrasound irradiation, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.     

Microwave Induced Synthesis of 3‐Aryl‐6‐(6‐/8‐substituted 4‐chloroquinoline‐3‐yl) ‐ s ‐triazolo [3,4‐b] −1,3,4‐thiadiazoles

The condensation of 4‐amino‐3‐aryl‐5‐mercapto‐1, 2, 4‐triazoles (1a‐f) with 6‐/8‐substituted 1,4‐dihydro‐4‐oxo‐quinoline‐3‐carboxylic adds (2a‐d) in the presence of phosphorus oxychloride on refluxng or under microwave irradiation gave twenty four novel 3‐aryl‐6‐ (6‐/8‐substituted 4‐chloroquinoline‐3‐yl)‐s‐triazolo[3,4‐b]‐1, 3,4‐thiadiazoles (4a‐x), Considerable increase in the reaction rate has been observed with improved yields under microwave irradiation. The structures of the compounds synthesized were determined by elemental analyses, IR, ¹H NMR and MS spectra. Their spectral properties and the reaction mechanism were also discussed. The preliminary biological test showed that some of compounds bad moderate antibacterial activities.     

Synthesis and Antimicrobial Activity of Novel 2‐Substituted Phenoxy‐N‐(4‐substituted Phenyl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐yl)acetamide Derivatives

A series of 2‐substituted phenoxy‐N‐(4‐substituted phenyl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazole‐2‐yl)acetamide derivatives 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i , 8j , 8k , 8l , 8m , 8n , 8o , 8p , 8q , 8r , 8s , 8t was synthesized by the reaction of phenoxyacetyl chloride 7 with intermediate 4‐substituted phenyl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐amine 5 . Their structures were confirmed by ¹H NMR, ¹³C NMR, MS, IR, and elemental analyses. The synthesized compounds were also screened for their antimicrobial activity against three types of plant fungi (Gibberella zeae , Phytophthora infestans , and Paralepetopsis sasakii ) and two kinds of bacteria [Xanthomonas oryzae pv. oryzae (Xoo ) and Xanthomonas axonopodis pv. citri (Xac )] showing promising results. In particular, 8b , 8f , 8g , and 8h exhibited excellent antibacterial activity against Xoo , with 50% effective concentration (EC₅₀) values of 35.2, 80.1, 62.5, and 82.1 µg/mL, respectively, which are superior to the commercial antibacterial agent bismerthiazol (89.9 µg/mL). The preliminary structure–activity relationship studies of these compounds are also briefly described.     

2‐(3,4‐Dichlorophenylimino)‐5‐((3‐(p‐substitutedphenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)methylene)thiazolidin‐4‐one as an Antibacterial,Antifungal and Antimycobacterial Agent

2‐(3,4‐Dichlorophenylimino)‐5‐((3‐(p‐substitutedphenyl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)methylene) thiazolidin‐4‐one has been selected as a target bio‐active molecules. Newly synthesized compounds were screened with Eschericha coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688), Staphylococcus aureus (MTCC 96), Streptococcus pyogenes (MTCC 442) for antibacterial, Candida albicans (MTCC 227), Aspergillus niger (MTCC 282), Aspergillus clavatus (MTCC 1323) for antifungal activity and H ₃₇ Rv for antimycobacterial activity. Compounds 3a , 3c , 3d , 3e , and 3h are potentially active against Staphylococcus aureus , while 3h is active against C. albicans . Compounds 3d and 3f are active against H ₃₇Rv for mycobacterium tuberculosis. Other possesses moderate to good activity. The structures of synthesized compounds were firmly established by well‐defined elemental analyses (C, H, N, S/O) and spectral analysis technique likes, IR, ¹H NMR and GC–MS.     

An efficient synthesis of 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles

Some new target products 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j have been synthesized by reaction of 2‐bromo‐1‐phenylethanone and compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j which were prepared from the combination of thiosemicarbazide and (E)‐3‐aryl‐1‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐prop‐2‐en‐1‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j . All the structures were established by MS, IR, CHN, and ¹H NMR spectra data. Synthesis of structure diversity is applied. J. Heterocyclic Chem., (2011).     

Heterocyclic Systems Containing Bridged Nitrogen Atom: Synthesis and Antibacterial Activity of 3‐(2‐Phenylquinolin‐4‐yl)/3‐(1‐p‐Chlorophenyl‐5‐methyl‐1,2,3‐triazol‐4‐yl)‐s‐triazolo[3,4‐b]‐1,3,4‐thiadiazine Derivatives

The condensation of 4‐amino‐5‐mercapto‐3‐(2‐phenylquinolin‐4‐yl)/3‐(1‐p‐chlorophenyl‐5‐methyl‐1,2,3‐triazol‐4‐yl)‐1,2,4‐triazoles 1a‐b with chloroacetaldehyde 2a‐b , ω‐bromo‐ω‐(1H‐1,2,4‐triazol‐1‐yl)acetophenone 3a‐b , chloranil 4a‐b , 2‐bromocyclohexanone 5a‐b , 2,4′‐dibromoacetophenone 6a‐b and 2‐bromo‐6′‐methoxy‐2′‐acetonaphthone 7a‐b are described. The structures of the compounds synthesized were confirmed by elemental analyses, IR, 1H NMR and mass spectra. The antibacterial activities were also evaluated.     

Synthesis and Bioactivities of Novel 1‐(3‐Chloropyridin‐2‐yl)‐N‐Substituted‐5‐(Trifluoromethyl)‐Pyrazole Carboxamide Derivatives

A series of novel 1‐(3‐chloropyridin‐2‐yl)‐N‐substituted‐5‐(trifluoromethyl)‐pyrazole carboxamide derivatives TC₁ , TC₂ , TC₃ , TC₄ , TC₅ , TC₆ , TC₇ , TC₈ , TC₉ , TC₁₀ , TC₁₁ were synthesized and characterized by IR, ¹H NMR, ¹³C NMR, MS, and elemental analysis. All the target compounds were tested in vitro for their antibacterial activities and antifungal activities. The preliminary bioassays indicated that compound TC₆ exhibited excellent activity against Xanthomonas oryzae (94.9% and 84.9%) at different concentrations (200 µg/mL and 100 µg/mL), which was higher than that of Bismerthiazol (94.6% and 64.0%), respectively. At the same time, most of the compounds exhibited moderate antifungal activities against four kinds of phytopathogenic fungi     

Synthesis and Antibacterial Activity of Novel (4‐Fluorophenyl)(4‐(naphthalen‐2‐yl)‐6‐aryl‐2‐thioxo‐2,3‐dihydropyrimidin‐1(6H)‐yl)methanone Derivatives

A novel series of (4‐fluorophenyl)(4‐(naphthalen‐2‐yl)‐6‐aryl‐2‐thioxo‐2,3‐dihydropyrimidin‐1(6H)‐yl)methanone derivatives were synthesized from reaction of 6‐(naphthalen‐2‐yl)‐4‐aryl‐3,4‐dihydropyrimidine‐2(1H)‐thiones with 4‐fluorobenzoylchloride in dichloromethane in the presence of triethylamine. The synthesized compounds were screened for antibacterial activity against Gram positive bacteria, namely, Staphylococcus aureus ATCC25923 and Listeria monocytogenes MTCC657, and Gram negative bacteria, namely, Escherichia coli ATCC25922 and Klebsiella pneumoniae ATCC700603, respectively. Some of the tested compounds showed significant antimicrobial activity.     

Synthesis and Bioactivities of Novel N‐(4‐(2‐Aryloxythiazol‐5‐yl)but‐3‐yn‐2‐yl)benzamides

A series of novel N‐(4‐(2‐aryloxythiazol‐5‐yl)but‐3‐yn‐2‐yl)benzamide derivatives were designed and synthesized. Their structures were identified by ¹H NMR and elemental analyses. Preliminary bioassays indicated that some title compounds provided >80% control of Sclerotinia sclerotiorum at 50 µg/mL and >70% herbicidal activities against B. campestris at 100 µg/mL. Their structure‐activities relationships were also discussed.     

Design,Synthesis and Biological Evaluation of Novel N‐(4‐([2,2′:5′,2′′‐Terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) Benzamide Derivatives

On the basis of the principle of combination of active groups, a series of novel N‐(4‐([2,2′:5′,2′′‐terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) benzamide derivatives were designed, synthesized and systematically evaluated for their antiviral activity against tobacco mosaic virus (TMV). The bioassay results showed that most of these compounds displayed good anti‐TMV activity, and some of them exhibited higher antiviral activity than commercial Ningnanmycin. Especially, compound 8e with excellent anti‐TMV activity (inactivation activity, 92.3%/500 µg·mL^?1; curative activity, 85.7%/500 µg·mL^?1 and protection activity, 64.7%/500 µg·mL^?1) emerged as a potential inhibitor of plant virus TMV. Quantitative structure‐activity relationship studies proved that the van der Waals volume (V) and electronic parameter (∑(∑σ_o+σ_p) and ∑σ_m) for the substituent R¹ were very important for antiviral activities in this class of compounds.     

Synthesis of Some Novel 4‐(Furan‐2‐yl)‐5,6‐dimethylpyridines

N‐2‐amino‐4‐(furan‐2‐yl)‐5,6‐dimethylnicotinonitrile ( 4 ) was utilized as key intermediate for the synthesis of some new, pyridopyrimidine, benzo[1,5][g]oxazocine, naphthoquinone, and isoindole derivatives. The structures of the newly synthesized compounds were confirmed by elemental analysis, IR, ¹H‐NMR, and mass spectral data.     

Two different one‐dimensional supramolecular chains formed from the reaction of 2‐[1‐(pyridin‐4‐ylmethyl)‐1H‐benzimidazol‐2‐yl]quinoline with two different precursors,Co(NO3)2 and CoCl2

Two different one‐dimensional supramolecular chains with Co^II cations have been synthesized based on the semi‐rigid ligand 2‐[1‐(pyridin‐4‐ylmethyl)‐1H‐benzimidazol‐2‐yl]quinoline (L), obtained by condensation of 2‐(1H‐benzimidazol‐2‐yl)quinoline and 4‐(chloromethyl)pyridine hydrochloride. Starting from different Co^II salts, two new compounds have been obtained, viz. catena‐poly[[[dinitratocobalt(II)]‐μ‐2‐[1‐(pyridin‐4‐ylmethyl)‐1H‐benzimidazol‐2‐yl]quinoline] dichloromethane monosolvate acetonitrile monosolvate], {[Co(NO₃)₂(C₂₂H₁₆N₄)]·CH₂Cl₂·CH₃CN}_n, (I) and catena‐poly[[[dichloridocobalt(II)]‐μ‐2‐[1‐(pyridin‐4‐ylmethyl)‐1H‐benzimidazol‐2‐yl]quinoline] methanol disolvate], {[CoCl₂(C₂₂H₁₆N₄)]·2CH₃OH}_n, (II). In (I), the Co^II centres lie in a distorted octahedral [CoN₃O₃] coordination environment. {Co(NO₃)₂L}_n units form one‐dimensional helical chains, where the L ligand has different directions of twist. The helical chains stack together via interchain π–π interactions to form a two‐dimensional sheet, and another type of π–π interaction further connects neighbouring sheets into a three‐dimensional framework with hexagonal channels, in which the acetonitrile molecules and disordered dichloromethane molecules are located. In (II), the Co^II centres lie in a distorted trigonal–bipyramidal [CoCl₂N₃] coordination environment. {CoCl₂L}_n units form one‐dimensional chains. The chains interact via C—H...π and C—H...Cl interactions. The result is that two‐dimensional sheets are generated, which are further linked into a three‐dimensional framework via interlayer C—H...Cl interactions. When viewed down the crystallographic b axis, the methanol solvent molecules are located in an orderly manner in wave‐like channels.     

Synthesis and Antifungal Screening of 2‐(2‐Aryl‐4‐methyl‐thiazol‐5‐yl)‐5‐((2‐aryl/benzylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole Derivatives

A new series of synthesis and biological screening of 2‐(2‐aryl‐4‐methyl‐thiazol‐5‐yl)‐5‐((2‐aryl/benzylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole derivatives 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i was achieved by condensation of 2‐(2‐aryl/benzylthiazol‐4‐yl)acetohydrazide 2a , 2b , 2c with 4‐methyl‐2‐arylthiazole‐5‐carbaldehyde 3a , 3b , 3c followed by oxidative cyclization of N'‐((4‐methyl‐2‐arylthiazol‐5‐yl)methylene)‐2‐(2‐aryl/benzylthiazol‐4‐yl)acetohydrazide 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i using iodobenzene diacetate as oxidizing agent. All the synthesized compounds were screened for their in vitro antifungal activity against Candida albicans, Candida tropicalis, Aspergillus niger, and Aspergillus flavus. Some of the synthesized compounds showed good antifungal activity.     

Facile Synthesis of N‐(Benzyl‐1H‐1,2,3‐Triazol‐5‐yl) Methyl)‐4‐(6‐Methoxybenzo [d] Thiazol‐2‐yl)‐2‐Nitrobenzamides via Click Chemistry

A series of novel N‐((l‐benzyl‐lH‐l,2,3‐triazol‐5‐yl) methyl)‐4‐(6‐methoxy benzo[d ]thiazol‐2‐yl)‐2‐nitrobenzamide derivatives were prepared from 4‐(6‐methoxybenzo[d ]thiazol‐2‐yl)‐2‐nitro‐N‐(prop‐2‐ynyl) benzamide with benzyl azides by using click reaction (copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction) in the presence of CuSO₄.5H₂O and sodium ascaorbate. All the newly synthesized compounds were evaluated further in vitro antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus and Bacillus subtillis ), Gram‐negative bacteria (Echerichia coli and Pseudomonas aeuroginosa ), and fungi (Aspergillus niger and Aspergillusfumigatus ) strains. The new compounds were characterized based on spectroscopic evidence. Among them compounds 10a , 10h , and 10i were showed promising activity when compared with standard drugs Ciprofloxacin and Miconazole.     

Facile Synthesis of Novel 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one Derivatives as Potential Anticancer Agents

A series of 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 6a – l ) derivatives has been efficiently synthesized by straightforward sequential reactions. Tandem Vilsmeier Hack reaction/cyclization/bromination/Suzuki cross‐coupling reactions were successfully applied to the preparation of title compounds in good‐to‐high yields. In the synthetic sequences, 3‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)acrylaldehydes ( 2 ) were found to react with ammonium thiocyanate to yield the corresponding 3‐(isothiazol‐5‐yl)‐2H‐chromen‐2‐ones ( 3 ). These derivatives were brominated with N‐bromo succinamide to yield the corresponding regioselective 3‐(4‐bromoisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 4 ). Finally, compound 4 was treated with various phenyl/pyrazole/7H –pyrrolo[2,3‐d]pyrimidinyl boronic acids 5a – l in the presence of K₂CO₃ and Pd catalyst in dimethylformamide to yield the corresponding title derivatives 6a – l . All the synthesized compounds were characterized by analytical and spectral studies. All the final compounds were screened against different cancer cell lines (A549, PC3, SKOV3, and B16F10), and among these compounds, 6b , 6g , 6h , and 6l displayed moderate cytotoxic activity against the tested cell lines.     

Synthesis of Novel Fluorescent 2‐{4‐[1‐(Pyridine‐2‐yl)‐1H‐pyrazol‐3‐yl] phenyl}‐2H‐naphtho [1,2‐d] [1,2,3] triazolyl Derivatives and Evaluation of Their Thermal and Photophysical Properties

Novel 2‐{4‐[1‐(pyridine‐2‐yl)‐1H‐pyrazol‐3‐yl] phenyl}‐2H‐naphtho [1,2‐d] [1,2,3] triazolyl fluorescent derivatives were synthesized from p‐nitrophenylacetic acid and 2‐hydrazino pyridine through Vilsmeier–Haack and diazotization reactions. Photophysical properties were evaluated, and results show that compounds have good fluorescence quantum yields. Thermal analysis showed that they are reasonably stable. The structures of the compounds were confirmed by FT‐IR, ¹H NMR, ¹³C NMR, and mass spectral and elemental analysis.     

Design and Synthesis of Novel 2‐(1,2,4‐triazol‐1‐yl)‐quinoline‐Based Tricyclic 1,5‐benzothiazepine Derivatives

A series of new tricyclic 1,5‐benzothiazepine derivatives containing 2‐(1,2,4‐triazol‐1‐yl)quinoline were synthesized by the reaction of 1,5‐benzothiazepine with benzohydroximinoyl chlorides via 1,3‐dipolar cycloaddition reaction. The structures of the target compounds were confirmed by IR, ¹H NMR, MS, elemental, and X‐ray crystallographic analysis.     

Synthesis of 5‐chloro‐2‐methyl‐3‐(5‐methylthiazol‐2‐yl)‐4(3H)‐quinazolinone and related compounds with potential biological activity

Eight new 2‐methyl‐4(3H)‐quinazolinones (8a‐8d, 9c, 9d, 10c, 10d) with one or two chlorine atoms in the benzene ring and a 5‐methyl‐1,3‐thiazol‐2‐yl, 4‐methyl‐1,3‐thiazol‐2‐yl, and 5‐ethyl‐1,3,4‐thiadiazol‐2‐yl substituent in position 3 of the heterocyclic ring were synthesized and characterized. The two step procedure (Scheme 1) utilizes chlorosubstituted anthranilic acids (3a‐3d) and acetic anhydride as the starting materials, with the respective chlorosubstituted 2‐methyl‐4H‐3,1‐benzoxazin‐4‐ones (4a‐4d) as the intermediates. The quinazoline derivatives were characterized by their melting points, elemental analyses and the mass, ultraviolet, infrared, and ¹H and ¹³C nmr spectra. The new compounds are expected to be biologically active.