Synthesis of New (Pyrazol‐3‐yl)‐1,3,4‐oxadiazole Derivatives by Unexpected Aromatization During Oxidative Cyclization of 4,5‐Dihydro‐1H‐pyrazole‐3‐carbohydrazones and Their Biological Activities

A series of novel 2‐(4‐(4‐chlorophenyl)‐1H‐pyrazol‐3‐yl)‐5‐(Aryl)‐1,3,4‐oxadiazoles were synthesized by unexpected aromatization during oxidative cyclization of 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1H‐pyrazole‐3‐carbohydrazones using chloramine‐T as an oxidant. The hydrazones were derived from 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1H‐pyrazole‐3‐carbohydrazide and various substituted aldehydes. The structure of the synthesized compounds was confirmed by FTIR, ¹H NMR, ¹³C NMR, and mass spectral data. The synthesized compounds were evaluated for their antitubercular and antioxidant activities. All the compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h and 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h showed good antitubercular activity against Mycobacterium tuberculosis (minimum inhibitory concentration = 25 µg/mL for 4f and 4g , 50–100 µg/mL for the rest). However, all the compounds exhibited poor antioxidant activity against 1,1‐diphenyl‐2‐picryl‐hydrazil free radical.     

Synthesis and antimicrobial activities of new 4,6‐diaryl‐ 4,5‐dihydro‐3‐hydroxy‐2H‐indazoles

A series of new 4,6‐diaryl‐4,5‐dihydro‐3‐hydroxy‐2H‐indazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k were synthesized by the cyclization of ethyl 2‐oxo‐4,6‐diarylcyclohex‐3‐ene carboxylates 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k . The compounds were characterized by IR, ¹H NMR, ¹³C NMR, 2D NMR, and elemental analysis. The synthesized compounds were evaluated for in vitro antibacterial and antifungal activities against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger, Aspergillus flavus, and Rhizopus sp. Most of the compounds exhibited good activity against the tested organisms. J. Heterocyclic Chem.,, (2012).     

Synthesis,characterization, and in vitro biological studies of some novel pyran fused pyrimidone derivatives

A variety of pyrano[2,3‐d]pyrimidine‐5‐one derivatives 5 , 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 6 , 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j have been synthesized from 6‐amino‐4‐(substituted phenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐1,4‐dihydropyrano[2,3‐c]pyrazole derivatives 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j via cyclization using formic acid and acetic acid. All the newly synthesized compounds have been characterized by IR, ¹H NMR, ¹³C NMR, and elemental analysis. All the synthesized compounds have been screened for antibacterial, antifungal and antitubercular activity. J. Heterocyclic Chem., (2012).     

Novel 5‐Methyl‐2‐[(un)substituted phenyl]‐4‐{4,5‐dihydro‐ 3‐[(un)substituted phenyl]‐5‐(1,2,3,4‐tetrahydroisoquinoline‐2‐yl)pyrazol‐1‐yl}‐oxazole Derivatives: Synthesis and Anticancer Activity

Eleven novel 5‐methyl‐2‐[(un)substituted phenyl]‐4‐{4,5‐dihydro‐3‐[(un)substituted phenyl]‐5‐(1,2,3,4‐tetrahydroisoquinoline‐2‐yl)pyrazol‐1‐yl}‐oxazole derivatives were synthesized and characterized by elemental analysis, ESI‐MS, ¹H NMR and ¹³C NMR. All of the compounds have been screened for their antiproliferative activities against PC‐3 cell (human prostate cancer) and A431 cell (human epidermoid carcinoma cancer) lines in vitro. The results revealed that compounds 4g , 4j and 4k exhibited the strong inhibitory activities against the PC‐3 cell lines (with IC₅₀ values of 2.8±0.11, 3.1±0.10 and 3.0±0.06 μg/mL, respectively).     

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 Optical Properties of Novel Fluorescence‐Traced Benzimidazolium Bromides

Seven novel fluorescence‐traced 1‐aryl‐2‐substituted‐3‐allyl‐1H‐benzimidazolium bromides ( 5a , 5b , 5c , 5d , 5e , 5f , 5g ) were synthesized by alkylation and quaternization of compounds 1‐aryl‐2‐substituted‐1H‐benzimidazoles ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) with excess allyl bromide in acetonitrile at refluxing temperature. Their structures were characterized by ¹H‐NMR, MS, and elemental analysis. They emit violet‐blue light (λ^Em_max = 386–438 nm) with fluorescence quantum yields of 0.54 to 0.75 in aqueous solution.     

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,Biological Activity of Pyrimidine Linked with Morpholinophenyl Derivatives

A new series of 5‐fluoro‐N⁴‐(3‐(4‐substitutedbenzylamino)phenyl)‐N²‐(4‐morpholinophenyl)pyrimidine‐2,4‐diamine derivatives ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j ) are prepared from using an intermediate compound 5‐fluoro‐N⁴‐(3‐(aminophenyl)‐N²‐(4‐morpholinophenyl)pyrimidine‐2,4‐diamine ( 5 ). The structures of the newly synthesized products are established from their spectral ¹H‐NMR, ¹³C‐NMR, ¹⁹F‐NMR, ESI‐MS, and analytical data. Here we report the synthesized compounds and larvicidal activity. All the compounds are screened for their significant larvicidal activity against third instar larvae at 24, 48, and 78‐h time exposure, and values were compared with standard drug Malathion. The Compounds 7i , 7a , 7c , 7f , and 7j exhibited significant activity. However the compounds 7b , 7e , 7d , and 7h showed excellent activity when compared to the above compounds and to standard drug malathion too because of the presence of mild electron withdrawing groups such as trifluoro, fluorine, hydroxy, nitro, and methoxy derivatives which are attached to the benzyl ring.     

Synthesis and Antifungal Activity Evaluation of Novel Substituted Pyrimidine‐5‐Carboxamides Bearing the Pyridine Moiety

A series of novel N‐(substituted phenyl/benzyl)‐2‐methylthio‐4‐((pyridin‐3‐ylmethyl)amino)pyrimidine‐5‐carboxamides were synthesized by multistep reactions. The structures of the target compounds were characterized by IR, ¹H NMR, ¹³C NMR, and elemental analysis. Their in vitro antifungal activities against two kinds of plant pathogenic fungi were evaluated by the mycelial growth rate method. The result showed that at the dosage of 100 μg/mL, several of these compounds exhibited moderate activity against Botrytis cinerea with inhibition rates of ~70%, and most compounds (e.g., 5a , 5c , 5e , 5f, and 5h ) possessed excellent activity against Sclerotinia Sclerotiorum with more than 90% inhibition rate.     

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,Characterization, and Biological Evaluation of Novel 3‐(4‐Chlorophenyl)‐2‐(substituted)quinazolin‐4(3H)‐one Derivatives as Multi‐target Anti‐inflammatory Agents

A novel class of 3‐(4‐chlorophenyl)‐2‐(substituted)quinazolin‐4(3H)‐one derivatives were synthesized, and the structure of synthesized compounds was characterized by IR, ¹H NMR, and mass spectroscopy. The newly synthesized compounds ( 4a–g and 6a–g ) were tested for their in vitro cyclooxygenase (COX) inhibition activity. The compounds have inhibitory profile against both COX‐1 and COX‐2, and some of the compounds are found to be selective against COX‐2. The compound 6g showed distinct inhibitory activity on COXs. The synthesized compounds were evaluated for their potential anti‐inflammatory activity as inhibitors of the proinflammatory cytokines IL‐6. Compounds 4d – g showed the highest level of inhibition among all the tested compounds. Thus, our data suggested that these compounds may represent a new class of potent anti‐inflammatory agents.     

A “One Pot,” Environmentally Friendly,Multicomponent Synthesis of 2‐Amino‐5‐cyano‐4‐[(2‐aryl)‐1H‐indol‐3‐yl]‐6‐hydroxypyrimidines and Their Antimicrobial Activity

A series of multifunctional 2‐amino‐5‐cyano‐4‐[(2‐aryl)‐1H‐indol‐3‐yl]‐6‐hydroxypyrimidines ( 4a , 4b , 4c , 4d , 4e , 4f ) was synthesized by multicomponent reaction of 3‐formylindole ( 1 ), cyanoethylacetate ( 2 ), and guanidine hydrochloride ( 3 ) with NaOH by using green chemical techniques, viz. microwave irradiation and grindstone technology. The same reactants when refluxed in ethanol also gave titled compounds ( 4a , 4b , 4c , 4d , 4e , 4f ). Compared with conventional procedure, the reaction can be carried out under milder conditions, requiring a shorter reaction time and giving higher yields following the green chemistry methodology. All the synthesized compounds have been characterized on the basis of elemental analyses and spectral data (IR, ¹H NMR, ¹³C NMR, and mass). All synthesized compounds were also evaluated for their antimicrobial activity against nine pathogenic bacteria, antifungal activity against Rhizopus stolonifer, Aspergillus flavus, and Fusarium oxysporum and antibacterial activity against Escherichia coli and Pseudomonas aeruginosa at different concentrations. Most of the compounds showed mild to moderate activity.     

Synthesis of 3-aminomethyl-substituted pyrazoles and isoxazoles

A series of new 3-(aminomethyl)pyrazoles and 3-(aminomethyl)isoxazoles was synthesized along a route involving the formation as key intermediates of esters of 5-substituted 1H-pyrazole-3-carboxylic and 1H-isoxazole-3-carboxylic acids. All compounds obtained were characterized by physicochemical constants, IR, ¹H, ¹³C NMR, and mass spectra.     

硫（醇）代N-对甲苯基/苯基磺酰基氨基羧酸酯类化合物的合成与神经营养活性

根据官能团的组合,设计合成了硫（醇）代N-对甲苯基/苯基磺酰基氨基羧酸酯类化合物,这些化合物的结构¹H NMR, ¹³C NMR, MS 和 HRMS证实,初步的实验结果表明：在10μg/mL浓度下,化合物4a, 4b, 4d, 5c, 5d, 5g, 6b和 6d显示对PC12细胞缺氧损伤具有显著的保护作用,化合物4c, 5b和 6c显示对PC12细胞缺氧损伤具有一定的保护作用;在5μg/mL浓度下,4d和 6d显示对PC12细胞缺氧损伤具有一定的保护作用;初步的实验也表明：在10μg/mL浓度下,4c, 5a, 5c, 5d, 5e和 6b显示对PC12细胞具有一定的促分化作用。     

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).     

Synthesis and Insecticidal Activity of Tetrazole‐Linked Triazole Derivatives

A new series of 4‐(4‐substitutedbenzylideneamino)‐5‐((1‐methyl‐1H‐tetrazol‐5‐ylthio)methyl)‐4H‐1,2,4‐triazole‐3‐thiol derivatives ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k ) are prepared using 4‐amino‐5‐((1‐methyl‐1H‐tetrazol‐5‐ylthio)methyl‐4H‐1,2,4‐triazole‐3‐thiol ( 4 ), as an intermediate compound. The structures of all the newly synthesized products are established supported by their spectral ¹H NMR, ¹³C NMR, FTIR, electrospray ionization mass spectrometry (mass), and analytical data. All the compounds are screened for their insecticidal activity against Plodia interpunctella, and six compounds exhibited significant activity.     

Synthesis and Antimicrobial Screening of Some Novel Chromones and Pyrazoles with Incorporated Isoxazole Moieties

The title compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h and 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h have been synthesized from β‐diketones and chromones, respectively, having 5‐methyl‐3‐phenylisoxazole moiety. Substituted 2‐acetylphenyl 5‐methyl‐3‐phenylisoxazole‐4‐carboxylate 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h were converted into 1‐(2‐hydroxyphenyl)‐3‐(5‐methyl‐3‐phenylisoxazole‐4‐yl)propane‐1,3‐dione 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h by Baker–Venketaraman transformation. Further, the cyclodehydration of diketone 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h with glacial acetic acid in conc. HCl at reflux gave corresponding substituted 2‐(5‐methyl‐3‐phenylisoxazole‐4‐yl)‐4H‐chromen‐4‐one 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h . The corresponding 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h react with hydrazine hydrate in presence of glacial acetic acid in ethanol at reflux to furnish 2‐(5‐5(5‐methyl‐3‐phenylisoxazole‐4‐yl)‐1H‐pyrazole‐3‐yl)phenol 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h . The structures of all newly synthesized compounds have been confirmed by IR, ¹H NMR, mass spectral data, as well as elemental analysis. The synthesized compounds have been screened for their antimicrobial activity. Some of the compounds show better antimicrobial activity as compared with the reference drugs Streptomycin, Ampicillin, Gentamycin, Cefixime, and Ketoconazole.     

The Synthesis,Spectral, and Electrochemical Characterization of Novel Alkoxybenzoquinone Derivatives

The novel monosubstituted benzoquinone compounds 3e , 3g , 3h ; 2,5‐O‐ substituted benzoquinone compounds 4a , 4b , 4c , 4d , 4e 4g and known compound 4h and 2,6‐O‐ substituted benzoquinone compounds 5e , 5f , 5g , 5h were obtained by the reaction of p‐chloranil ( 1 ) and related alcohol compounds in potassium carbonate (K₂CO₃) solution of acetonitrile or chloroform with Et₃N. The novel cyclic compounds 7 , 8 and 10 , 11 were obtained from the reaction of p‐chloranil ( 1 ) and diols in potassium carbonate (K₂CO₃) solution of acetonitrile at room temperature. The structures of novel compounds were characterized by using micro analysis, FT‐IR, ¹H‐NMR, ¹³C‐NMR, MS and cyclic voltammetry.     

The synthesis,structural characterization and biological evaluation of N‐(ferrocenylmethyl amino acid) fluorinated benzene‐carboxamide derivatives as potential anticancer agents

A series of N‐(ferrocenylmethyl amino acid) fluorinated benzene‐carboxamide derivatives 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i and 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i have been synthesized by coupling ferrocenylmethyl amine 3 with various substituted N‐(fluorobenzoyl) amino acid derivatives using the standard N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride, 1‐hydroxybenzotriazole protocol. The amino acids employed in this study were glycine and L‐alanine. All of the compounds were fully characterized using a combination of ¹H NMR, ¹³C NMR, ¹⁹F NMR, distortionless enhancement by polarization transfer (DEPT)‐135, ¹H–¹H correlation spectroscopy (COSY) and ¹H–¹³C COSY (heteronuclear multiple‐quantum correlation) spectroscopy. The compounds were biologically evaluated on the oestrogen‐positive MCF‐7 breast cancer cell line. Compounds 4g , 4i , 5h and 5i exhibited cytotoxic effects on the MCF‐7 breast cancer cell line. N‐(Ferrocenylmethyl‐L‐alanine)‐3,4,5‐trifluorobenzene‐carboxamide ( 5h ) was the most active compound, with an IC₅₀ value of 2.84 μm . Compounds 4i , 5h and 5i had lower IC₅₀ values than that found for the clinically employed anticancer drug cisplatin (IC₅₀ = 16.3 μm against MCF‐7). Guanine oxidation studies confirmed that 5h was capable of generating oxidative damage via a reactive oxygen species‐mediated mechanism. Copyright © 2013 John Wiley & Sons, Ltd.     

Isoxazole derivatives of silatrane: synthesis,characterization, in silico ADME profile,prediction of potential pharmacological activity and evaluation of antimicrobial action

A new family of mono- ( 3a-h ) and bis- ( 4a-g ) isoxazole-bridged silatranes has been synthesized by the reaction of 3-aminopropylsilatrane ( 1 ) and 3-substituted 5-chloro-methylisoxazoles ( 2a-h ). The structure of the isoxazole-silatrane hybrids is characterized by elemental analysis, FT-IR, UV, NMR (¹H, ¹³C,²⁹Si and ¹⁵N) spectroscopy, high-resolution mass spectrometry, and X-ray diffraction analysis. The in silico ADME (absorption, distribution, metabolism, excretion) assessment reveals that properties of mono-adducts ( 3a-h ) are similar to those of drugs obeyed to the Lipinski's rule. The calculated screening of potential pharmacological activity profiles (in silico PASS program) of isoxazole-silatranes shows that all synthesized compounds (both mono- and bis-substituted) may have high antitumor action, unlike starting isoxazoles. The preliminary screening of the synthesized silatranes for antimicrobial activity against Enterococcus durans, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa indicates that all test samples are active only against gram-positive microorganisms. Silatrane 3f displays minimal inhibitory concentration (MIC 12.5 and 6.2 μg ml⁻¹) against E. durans and B. subtilis as compared with standard drug gentamicin (MIC 25 and 50 μg ml⁻¹).