Journal articles: 'Heterocyclic chemistry : Pyridine'

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Boyd, Derek R., Narain D. Sharma, Ludmila V. Modyanova, Jonathan G. Carroll, John F. Malone, Christopher CR Allen, John TG Hamilton, David T. Gibson, Rebecca E. Parales, and Howard Dalton. "Dioxygenase-catalyzed cis-dihydroxylation of pyridine-ring systems." Canadian Journal of Chemistry 80, no. 6 (June 1, 2002): 589–600. http://dx.doi.org/10.1139/v02-062.

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Toluene dioxygenase-catalyzed dihydroxylation, in the carbocyclic rings of quinoline, 2-chloroquinoline, 2-methoxyquinoline, and 3-bromoquinoline, was found to yield the corresponding enantiopure cis-5,6- and -7,8-dihy dro diol metabolites using whole cells of Pseudomonas putida UV4. cis-Dihydroxylation at the 3,4-bond of 2-chloroquino line, 2-methoxyquinoline, and 2-quinolone was also found to yield the heterocyclic cis-dihydrodiol metabolite, (+)-cis-(3S,4S)-3,4-dihydroxy-3,4-dihydro-2-quinolone. Heterocyclic cis-dihydrodiol metabolites, resulting from dihydroxylation at the 5,6- and 3,4-bonds of 1-methyl 2-pyridone, were isolated from bacteria containing toluene, naphthalene, and biphenyl dioxygenases. The enantiomeric excess (ee) values (>98%) and the absolute configurations of the carbocyclic cis-dihydrodiol metabolites of quinoline substrates (benzylic R) and of the heterocyclic cis-diols from quinoline, 2-quinolone, and 2-pyridone substrates (allylic S) were found to be in accord with earlier models for dioxygenase-catalyzed cis-dihydroxylation of carbocyclic arenes. Evidence favouring the dioxygenase-catalyzed cis-dihydroxylation of pyridine-ring systems is presented.Key words: dioxygenases; cis-dihydroxylation, pyridines, 2-pyridones, absolute configurations.

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Hafez, Hend N., and Abdel-Rahman B. A. El-Gazzar. "Synthesis of Novel Pyridine Bearing Biologically Active Imidiazolyl, Pyrazolyl, Oxa/thiadiazolyl and Urea Derivatives as Promising Anticancer Agents." Current Organic Synthesis 17, no. 1 (February 24, 2020): 55–64. http://dx.doi.org/10.2174/1570179417666191223163225.

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Background: A novel series of pyridine containing 1,3,4-oxa/thiadiazol derivatives 4a,b, pyrazole derivatives 5-7, thiazole derivatives 9a,b and 17a-c, urea derivatives 12a-c, imidiazole derivative 16, imidazo[1,2-a]pyridine derivatives 18a, b, tetrazole 19, pyrane 20 and pyridine derivatives 21 has been synthesized. Objective: This research aims to synthesize 6-(Trifluoromethyl)-2-[3-(trifluoromethyl)phenyl] amino nicotinohydrazide 2 and 6-(trifluoromethyl)-2-[3-(trifluoromethyl)phenyl]amino pyridin-3-carboaldhyde 15 as key intermediate for the synthesis of novel pyridine derivatives bearing different heterocyclic rings in order to study the additive effect of this ring toward tumor cell lines. Methods: 6-(Trifluoromethyl)-2-[3-(trifluoromethyl)phenyl]amino nicotinohydrazide 2 was synthesized in a series of synthetic steps and was used as key intermediate for the synthesis of compounds 3-(1,3,4- oxa/thiadiazol-2-yl)-6-(trifluoromethyl)-N-(3- trifluoromethyl) phenyl) pyridin-2-amine 4a,b, (3,5-dimethyl- 1H-pyrazol-1-yl derivatives) [6-(trifluoromethyl)-2-[3- trifluoromethyl) phenyl] amino pyridin-3- yl]methanone 5a,b, 6-8, 9a,b and 12a-c. Also, 6-(trifluoromethyl)-2-[3-(trifluoromethyl)phenyl]amino pyridin-3-carboaldhyde (15) was used as a key intermediate for the synthesis of novel series of pyridine derivatives with different heterocyclic ring (16-21). Results: Structures of the newly synthesized compounds were established by elemental analysis and spectral data. All the synthesized compounds were screened for their in vitro anticancer activity against liver cancer (HepG2), human colon cancer (HT-29) and human breast adenocarcinoma cell lines (MCF-7). Conclusion: All the synthesized compounds were investigated for their in vitro antitumor activity. Compounds 4b, 9a,b and 19 showed higher antitumor activity than the doxorubicin. Interestingly, pyridine with pfluorophenyl urea 12a demonstrated the most potent antitumor activity. The activity of these compounds is strongly dependent on the basic skeleton of the molecules and the nature of the heterocyclic ring attached to the pyridine moiety.

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Monier, Mohamed, Doaa Abdel-Latif, Ahmed El-Mekabaty, Başak D. Mert, and Khaled M. Elattar. "Advances in the Chemistry of 6-6 Bicyclic Systems: Chemistry of Pyrido[3,4- d]pyrimidines." Current Organic Synthesis 16, no. 6 (November 26, 2019): 812–54. http://dx.doi.org/10.2174/1570179416666190704113647.

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The aim of this work is to discuss the chemistry of pyrido[3,4-d]pyrimidines as one of the most important heterocyclic compounds with remarkable synthetic, biological and medical applications. In this overview, the chemistry of heterocyclic compounds incorporated the pyrido[3,4-d]pyrimidine scaffold as demonstrated by chemical reactions and different preparation processes. The anticipated compounds were synthesized from pyridine or pyrimidine compounds and a description of the reactivity of substituents attached to ring carbon and nitrogen atoms is discussed. On the other hand, the synthesis and reactions of fused heterocycles incorporated pyrido[3,4-d]pyrimidine scaffold is described. The diamine analogs included pyrido[3,4-d]pyrimidine core were reported as tyrosine kinase inhibitors. The chemical reactions of certain unexpected and chemically substantial compounds have been discussed.

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Li, Dongli, Panpan Wu, Ning Sun, Yu-Jing Lu, Wing-Leung Wong, Zhiyuang Fang, and Kun Zhang. "The Diversity of Heterocyclic N-oxide Molecules: Highlights on their Potential in Organic Synthesis, Catalysis and Drug Applications." Current Organic Chemistry 23, no. 5 (July 1, 2019): 616–27. http://dx.doi.org/10.2174/1385272823666190408095257.

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The synthesis and chemistry of heterocyclic N-oxide derivatives such as those from pyridine and indazole are very well-known due to their usefulness as versatile synthetic intermediates and their biological importance. These classes of organic compounds have been demonstrated in many interesting and amazing functionalities, particularly vital in the areas including metal complexes formation, catalysts design, asymmetric catalysis and synthesis, and medicinal applications (some potent N-oxide compounds with anticancer, antibacterial, anti-inflammatory activity, etc.). Therefore, the heterocyclic N-oxide motif has been successfully employed in a number of recent advanced chemistry and drug development investigations. In the present review, our primary aim was to provide a relevant summary focusing on the topics of organic synthesis and medical application potential of the compounds cited, which could be attractive and give some insights to researchers in the field. Therefore, we mainly highlight the importance of heterocyclic N-oxide derivatives including those synthesized from imidazole, indazole, indole, pyridazine, pyrazine, pyridine, and pyrimidine in organic syntheses and catalysis, and drug applications. Over the past years, a number of reviews have been published on the organic synthesis and catalysis of N-oxides. We thus concentrated on highlighting those rarely mentioned or recently reported systems.

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Zakirova, Gladis G., Dmitrii Yu Mladentsev, and Nataliya N. Borisova. "An Approach to Nonsymmetric Bis(tertiary phosphine oxides) Comprising Heterocyclic Fragments via the Pd-Catalyzed Phosphorylation." Synlett 31, no. 18 (August 26, 2020): 1833–37. http://dx.doi.org/10.1055/s-0040-1706419.

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Nonsymmetric tertiary phosphine oxides with different five- and six-membered heterocyclic fragments such as pyridine, 2,2′-bipyridine, 1,10-phenantroline, quinoline, imidazole, and thiazole were synthesized in good yields via the successive introduction of phosphine oxide groups into the initial dihalogenated heterocycles by means of Pd-catalyzed phosphorylation reaction. The synthesis of pyridine-type compounds is hindered by competing double coupling, while for five-membered heterocycles the principal difficulty is the dehalogenation. Both side processes were successfully suppressed by the use of an excess of a dihalide (which can be easily recovered during the product purification step), proper phosphine ligand for palladium, and nonpolar solvent such as toluene.

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Mercer, Frank W., and Martin T. McKenzie. "Dielectric and thermal characterization of fluorinated polyimides containing heterocyclic moieties." High Performance Polymers 5, no. 2 (April 1993): 97–106. http://dx.doi.org/10.1088/0954-0083/5/2/002.

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A series of fluorinated polyinides and fluorinated polyimides containing heterocyclic moieties were prepared and investigated to determine their dielectric constants, dielectric constants as a function of relative humidity (RH) and thermal properties. Thle fluorinated polyimides containing heterocyclic moieties were prepared from diamines containing pyridine, pyridazine, oxadiazole or benzoxazole moieties. The properties of the fluorinated heterocyclic-containing polyimides were compared with those of fluorinated polyimides prepared from aromatic diamines. In most cases, the introduction of heterocyclic moieties caused an increase in dielectric constant, an increase in the dielectric constant as a function of relative humidity and a decrease in thermal stability compared with the polyimides prepared with aromatic diamines.

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Abdel Hafez, Ali A., Ibrahim M. A. Awad, and Raga A. Ahmed. "New Heterocyclo-Substituted Pyrazolo[3,4-b]pyridine Derivatives." Collection of Czechoslovak Chemical Communications 58, no. 5 (1993): 1198–202. http://dx.doi.org/10.1135/cccc19931198.

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In this investigation and in continuance with our previous work in the synthesis of some heterocyclic compounds fused with pyridine moiety, we used 3-amino-4,6-diphenyl-1H-pyrazolo[3,4-b]pyridine (II) as starting material to synthesize many heterocyclic compounds containing pyrazolopyridine moiety.

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Khalifa, Mohamed E., and Adel A. Gobouri. "Biological screening and assessment of certain substituted monoazo heterocycles containing sulphur and / or nitrogen and their seleno like moieties." Polish Journal of Chemical Technology 19, no. 4 (December 1, 2017): 28–35. http://dx.doi.org/10.1515/pjct-2017-0064.

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Abstract The monoazo substituted five membered heterocycles, along with their seleno like moieties are still of interest in organic chemistry due to their medicinal and valuable applications. In continuation of our interest in the study of heterocyclic azo compounds containing sulphur and / or nitrogen heteroatoms, the synthesis of 5-aryl mono azo-thiazol-2-ylcarbamoyl-thiophene along with their seleno like derivatives of pyridine, pyridazine and quinolone, were accomplished. All the synthesized compounds were in vitro screening of their antioxidant activity, antitumor activity against Ehrlich ascites carcinoma cell EACC cell line and antimicrobial activity against various pathogenic microorganisms, such as Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and fungi strains of Aspergillus flavus and Candida albicans. The structural–activity relationship was studied based on the obtained data.

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Mohareb, R. M., and S. M. Fahmy. "Reaction of Malononitrile and Ethyl Cyanoacetate: a Novel Synthesis of Polyfunctional Pyridine Derivatives." Zeitschrift für Naturforschung B 40, no. 11 (November 1, 1985): 1537–40. http://dx.doi.org/10.1515/znb-1985-1120.

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Malononitrile reacts with ethyl cyanoacetate to give a polyfunctional substituted pyridine derivative 5. The latter compound reacts with aniline, hydrazines and aromatic aldehydes to give condensated products. The active methylene of 5 couples with benzenediazonium chloride to give the phenylhydrazone derivative which cyclises readily to give a pyrido[2,3-d]pyridazine derivative. 5 reacts with trichloroacetonitrile, and carbon disulphide to give fused heterocyclic derivatives.

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10

Xia, Liang, Yan Zhang, Jingbo Zhang, Songwen Lin, Kehui Zhang, Hua Tian, Yi Dong, and Heng Xu. "Identification of Novel Thiazolo[5,4-b]Pyridine Derivatives as Potent Phosphoinositide 3-Kinase Inhibitors." Molecules 25, no. 20 (October 12, 2020): 4630. http://dx.doi.org/10.3390/molecules25204630.

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A series of novel 2-pyridyl, 4-morpholinyl substituted thiazolo[5,4-b]pyridine analogues have been designed and synthesized in this paper. These thiazolo[5,4-b]pyridines were efficiently prepared in seven steps from commercially available substances in moderate to good yields. All of these N-heterocyclic compounds were characterized by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) analysis and tested for phosphoinositide 3-kinase (PI3K) enzymatic assay. The results indicated that these N-heterocyclic compounds showed potent PI3K inhibitory activity, and the IC50 of a representative compound (19a) could reach to 3.6 nm. The structure−activity relationships (SAR) study showed that sulfonamide functionality was important for PI3Kα inhibitory activity, and 2-chloro-4-florophenyl sulfonamide (19b), or 5-chlorothiophene-2-sulfonamide (19c) showed potent inhibitory activity with a nanomolar IC50 value. The pyridyl attached to thiazolo[5,4-b]pyridine was another key structural unit for PI3Kα inhibitory potency, and replacement by phenyl lead to a significant decrease in activity. Enzymatic Inhibition results showed that compound 19a inhibited PI3Kα, PI3Kγ, or PI3Kδ with a nanomolar IC50 value, but its inhibitory activity on PI3Kβ was approximately 10-fold reduced. Further docking analysis revealed that the N-heterocyclic core of compound 19a was directly involved in the binding to the kinase through the key hydrogen bonds interaction.

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Mohareb, R. M., and S. M. Fahmy. "Activated Nitriles in Heterocyclic Synthesis: A Novel Synthesis of Pyridazine, Pyrimidine, Pyridine and Pyrano[4,3-b]pyridine Derivatives." Zeitschrift für Naturforschung B 40, no. 5 (May 1, 1985): 664–68. http://dx.doi.org/10.1515/znb-1985-0518.

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Abstract Diethyl-3-amino-2-cyano-2-pentendioate (1) reacts with aromatic amines and aminohetero-cyclic compounds to yield amide derivatives (2 c-h). The latter derivatives were utilised in synthesis of pyridazines (4a, b), pyrimidine (6), pyridone (9) and pyrano[4,3-b]pyridine (16a, b) derivatives via reaction with aryldiazonium chloride, trichloroacetonitrile, sodiummethoxide and cinnamonitrile derivatives, respectively.

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Gad-Elkareem, Mohamed A. M., Azza M. Abdel-Fattah, and Mohamed A. A. Elneairy. "Pyrazolo[3,4-b]pyridine in heterocyclic synthesis: synthesis of new pyrazolo[3,4-b]pyridines, imidazo[1',2':1,5]pyrazolo[3,4-b]pyridines, and pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidines." Canadian Journal of Chemistry 85, no. 9 (September 1, 2007): 592–99. http://dx.doi.org/10.1139/v07-089.

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Pyrazolo[3,4-b]pyridine derivatives 7 and 9 were synthesized via the reaction of 3-amino-1H-pyrazolo-[3,4-b]pyridine derivative 2 with ω-bromoacetophenones. Reaction of 7 and 9 with Ac2O afforded the imidazo[1',2':1,5]py razolo[3,4-b]pyridine derivative 8 and pyrazolo[3,4-b]pyridine derivative 10, respectively. Reaction of 2 with chloroacetonitrile followed by DMF-DMA gave imidazo[1',2':1,5]pyrazolo[3,4-b]pyridines 4 and 5, respectively. Acetyl acetone and 1,1-dicyano-2,2-dimethylthioethene were reacted with 2 to afford the pyrido[2',3':3,4]pyrazolo-[1,5-a]-pyrimidines 11 and 14, respectively. Also, 2 reacted with DMF-DMA to yield the formamidine 15, which in turn, reacted with active methylene reagents, yielding the corresponding pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidines 18 and 23a-23d.Key words: 1H-pyrazolo[3,4-b]pyridines, imidazo[1',2':1,5]pyrazolo[3,4-b]pyridines, pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidines.

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13

Xu, Xiaowen, Richard Hoogenboom, and Kristof Van Hecke. "Crystal structures of three N-(pyridine-2-carbonyl)pyridine-2-carboxamides as potential ligands for supramolecular chemistry." Acta Crystallographica Section E Crystallographic Communications 77, no. 9 (August 24, 2021): 958–64. http://dx.doi.org/10.1107/s2056989021008562.

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The synthesis and single-crystal X-ray structures of three N-(pyridine-2-carbonyl)pyridine-2-carboxamide imides, with or without F atoms on the 3-position of the pyridine rings are reported, namely, N-(pyridine-2-carbonyl)pyridine-2-carboxamide, C12H9N3O2 (1), N-(3-fluoropyridine-2-carbonyl)pyridine-2-carboxamide, C12H8FN3O2 (2), and 3-fluoro-N-(3-fluoropyridine-2-carbonyl)pyridine-2-carboxamide, C12H7F2N3O2 (3). The above-mentioned compounds were synthesized by a mild, general procedure with an excellent yield, providing straightforward access to symmetrical and/or asymmetrical heterocyclic ureas. The crystal structures of 1 and 2 are isomorphous, showing similar packing arrangements, i.e. double layers of parallel (face-to-face) molecules alternating with analogous, but perpendicularly oriented, double layers. In contrast, the crystal structure of 3, containing a fluoro- group at the 3-position of both pyridine rings, shows molecular arrangements in a longitudinal, tubular manner along the c axis, with the aromatic pyridine and carbonyl/fluorine moieties facing towards each other.

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Su, Biyun, Yifan Hou, Li Wang, Xiaoteng Li, Dandan Pan, Tingyu Yan, Ao Zhang, Faida Paison, and Liqing Ding. "The Syntheses, Characterization and Crystal Structures of a Series of Heterocyclic β-Diketones and Their Isoxazole Compounds." Current Organic Synthesis 16, no. 8 (January 20, 2020): 1174–84. http://dx.doi.org/10.2174/1570179416666191022113022.

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Background: In the field of coordination chemistry, the introduction of heterocyclic substituents into the structure of β-diketone enables ligand to produce multiple coordination sites. The adoption of small steric oxime group into the structure of heterocyclic β-diketone by Schiff-base condensation will further increase coordination sites and facilitate the generation of polynuclear structures. Objective: A series of β-diketones (2a-2c) containing different heterocycles such as pyridine, thiophene and furan and their corresponding isoxazole compounds (3a-3c) were synthesized. Materials and Methods: The Claisen condensations were investigated in a solvent-free rheological phase system at room temperature to obtain heterocyclic β-diketones 2a-2c, which further reacted with hydroxylamine hydrochloride to obtain heterocyclic isoxazoles 3a-3c. All these compounds were well characterized by EA, IR, 1H NMR and X-ray crystal diffraction to confirm the structures. Synthetic mechanisms of compounds and the effects of different heterocycles on reactivity were discussed deeply. Result: 1H NMR indicated that these β-diketones do not exist as a total diketonic form but an equilibration between diketone and enol forms in CDCl3 solvent, in which the enol form accounts for 98.0% in 2a, 94.3% in 2b, 95.5% in 2c. While the crystal structures of 2a-2c showed that the reaction allows to isolate diketones in solid state. Crystal structures of 3a-3c showed that the neutral β-ketone oximes resonate and cyclize to form the target heterocyclic isoxazoles. Conclusion: SN1 nucleophilic substitution mechanism of Claisen ketoester condensation was proposed for the syntheses of 2a-2c, and SN1 single molecule nucleophilic substitution reaction mechanism was put forward for 3a-3c.

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Mohammadi, Samaneh, Mehdi Pordel, Sadegh Allameh, and Hamed Chegini. "Synthesis of New Dyes from Imidazo[1,2-a]Pyridine: Tautomerism, Spectroscopic Characterisation, DFT/TD-DFT Calculations, Atoms in Molecules Analyses and Antibacterial Activities." Journal of Chemical Research 41, no. 3 (March 2017): 143–48. http://dx.doi.org/10.3184/174751917x14873588907684.

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The synthesis, optical properties, theoretical calculations and antibacterial activity of a series of new heterocyclic dyes from imidazo[1,2-a] pyridine are described. The key intermediate 2-[3-(hydroxyimino)imidazo[1,2-a]pyridin-2(3H)-ylidene]malononitrile was obtained via the nucleophilic substitution of hydrogen in 3-nitroimidazo[1,2-a]pyridine with malononitrile in basic methanol solution. Tautomerism, oxidation and alkylation studies on the dye led to the synthesis of new heterocyclic indigo-coloured, purple, and orange dyes in good yields. The structures of all newly synthesised compounds were confirmed by spectral and analytical data. The optical properties of the dyes were spectrally characterised and shown to exhibit interesting photophysical properties including high extinction coefficients. Density functional theory calculations of the dyes were performed to provide the optimised geometries and relevant frontier orbitals. Calculated electronic absorption spectra were also obtained by the time-dependent density functional theory method. In addition, electrostatic potential maps and electron density maps of the dyes were evaluated by AIM (atoms in molecules) analysis. Moreover, the new dyes exhibited potent antibacterial activity and their antibacterial activities (MIC) against Gram-positive and Gram-negative bacterial species were determined.

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Watson, AA, DA House, and PJ Steel. "Chiral Heterocyclic Ligands. VIII. Syntheses and Complexes of New Chelating Ligands Derived From Camphor." Australian Journal of Chemistry 48, no. 9 (1995): 1549. http://dx.doi.org/10.1071/ch9951549.

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The syntheses of 23 new chelating ligands are described. Most of these ligands are derived from the chiral pyrazole (1) which has been linked to a variety of heterocycles , namely pyridine, pyrimidine, pyridazine, isoxazole , benzimidazole, thiophen and furan. In certain cases the parent achiral analogues have also been prepared. Preliminary studies of the coordination chemistry of these ligands with selected transition metals have been carried out. The X-ray crystal structures of palladium complexes of isoxazole- and thiophen-containing ligands have also been determined.

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Agamy, Samia Michel, Mervat Mohammed Abdel-Khalik, Mona Hassan Mohamed, and Mohammed Hilmy Elnagdi. "Enaminones as Building Blocks In Heterocyclic Synthesis: A New One Pot Synthesis of Polyfunctional Substituted Pyridines." Zeitschrift für Naturforschung B 56, no. 10 (October 1, 2001): 1074–78. http://dx.doi.org/10.1515/znb-2001-1016.

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Enaminones react with a variety of active methyl and methylene reagents in presence of ammonium acetate to yield functionally substituted pyridines in good yields. The reaction proceeded via initial Michael addition across the double bond followed by cyclization. The reaction of enaminone with aromatic aldehyde in acetic acid/ammonium acetate afforded the dihydropyridine that was oxidized to the corresponding pyridine.

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Singh, Rashmi, Tomas Horsten, Rashmi Prakash, Swapan Dey, and Wim Dehaen. "Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues." Beilstein Journal of Organic Chemistry 17 (April 30, 2021): 977–82. http://dx.doi.org/10.3762/bjoc.17.79.

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Several new heterocyclic systems based on a hydroxybenzofuro[2,3-b]pyridine building block were prepared. This benzofuropyridine is easily available from the Meerwein reaction of benzoquinone and a heterocyclic diazonium salt, followed by reduction and cyclization. Electrophilic substitution and further condensations give polycyclic systems, including oxazolo- and chromeno-fused analogues.

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Amr, Abd El-Galil E., Ashraf M. Mohamed, and Alhussein A. Ibrahim. "Synthesis of Some New Chiral Tricyclic and Macrocyclic Pyridine Derivatives as Antimicrobial Agents." Zeitschrift für Naturforschung B 58, no. 9 (September 1, 2003): 861–68. http://dx.doi.org/10.1515/znb-2003-0908.

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A series of chiral macrocyclic pyridines has been prepared starting from N2,N2-(pyridine- 2,6-dicarbonyl)diamino acid hydrazides (2a-c) and N,N-bis-(1-carboxy-2-substituted)-2,6- diaminocarbonyl)pyridines (3a,b). The coupling of (2a-c) with 2,6-pyridine dicarbonyldichloride (4) gave the compounds (5a-c). Compounds 2a-c were coupled with 2,6-diacetylpyridine (6) to yield compounds (7a-c) and with heterocyclic aldehydes (8) or (10) to give the compounds (9a-c) or (11a-c). In addition, the hydrazides (2a-c) were reacted with diformylcalix[4]arene 12 to afford the macrocyclic calix[4]arene hydrazone derivatives (13a-c) in reasonable yields. Finally, reaction of diaminocalix-[4]arene derivatives (14a,b) with hydrazides 2a,b or acids (3a,b), using azide or mixed anhydride methods afforded macrocyclic calix[4]arene derivatives 15a,b and 16a,b, respectively. The structure assignments of the new compounds are based on chemical and spectroscopic evidence. The biological activity screening tests showed that many of the obtained compounds exhibit high antimicrobial activity comparable to ampicillin and chloramphenicol which are used as reference compounds.

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Naziruddin, Abbas Raja, Chen-Shiang Lee, Wan-Jung Lin, Bing-Jian Sun, Kang-Heng Chao, Agnes Hsiu Hwa Chang, and Wen-Shu Hwang. "Platinum complexes bearing normal and mesoionic N-heterocyclic carbene based pincer ligands: syntheses, structures, and photo-functional attributes." Dalton Transactions 45, no. 13 (2016): 5848–59. http://dx.doi.org/10.1039/c5dt04770f.

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Poormirzaei, Nazanin, Mehdi Pordel, Elnaz Yaghoobi, Saeed Shojaee, Masoud Aminiyanfar, and Atoosa Gonabadi. "3-(Hydroxyimino)imidazo[1,2-a]pyridin-2(3H)-ylidene)-1-arylethanones as new red heterocyclic dyes: Synthesis, spectral studies, quantum-chemical investigations, and antibacterial activities." Journal of Chemical Research 44, no. 3-4 (December 10, 2019): 167–73. http://dx.doi.org/10.1177/1747519819893060.

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The synthesis, optical properties, theoretical calculations, and antibacterial activities of a series of new red heterocyclic dyes derived from imidazo[1,2- a]pyridine are presented. 3-(Hydroxyimino)imidazo[1,2- a]pyridin-2(3 H)-ylidene)-1-arylethanones are obtained from the reaction of 3-nitroimidazo[1,2- a]pyridine with substituted acetophenone derivatives in good yields (65%–72%). The structures are confirmed by spectral and analytical data, and the optical properties of the dyes are characterized by spectrophotometry. Density functional theory calculations are performed to provide the optimized geometries and relevant frontier orbitals. Calculated electronic absorption spectra are also obtained by the time-dependent density functional theory method. Moreover, the antibacterial activities (minimum inhibitory concentration) of the new dyes against Gram-positive and Gram-negative bacterial species are determined (minimum inhibitory concentration: 5–200 μg mL−1).

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Zhu, Yan-Qiu, Rui Zhang, Wei Sang, Hua-Jing Wang, Yuan Wu, Bao-Yi Yu, Jun-Chao Zhang, Hua Cheng, and Cheng Chen. "Ligand-controlled palladium catalysis enables switch between mono- and di-arylation of primary aromatic amines with 2-halobenzothiazoles." Organic Chemistry Frontiers 7, no. 15 (2020): 1981–90. http://dx.doi.org/10.1039/d0qo00361a.

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Węcławski, Marek K., Irena Deperasińska, Arkadiusz Leniak, Marzena Banasiewicz, Bolesław Kozankiewicz, and Daniel T. Gryko. "Unexpected formation of π-expanded isoquinoline from anthracene possessing four electron-donating groups via the Duff reaction." Organic & Biomolecular Chemistry 14, no. 29 (2016): 7046–52. http://dx.doi.org/10.1039/c6ob00981f.

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Agbodan, Kokou Agbékonyi, Oudjaniyobi Simalou, Gneiny Whad Tchani, and Koffi Jondo. "Etude de l’influence de la basicité sur l’enthalpie de réaction des sels N-méthoxycarbonyl-(oxy)-pyridiniums." International Journal of Biological and Chemical Sciences 14, no. 4 (August 17, 2020): 1489–98. http://dx.doi.org/10.4314/ijbcs.v14i4.26.

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Les hétérocycles sont importants, aussi bien dans les domaines biologique, médicinal et thérapeutique (vitamines, hormones, antibiotiques, etc), que dans le secteur industriel et technologique (inhibiteurs de corrosion, colorants, agents stabilisants, pesticides, herbicides. Les chloroformiates ou chlorocarbonates sont les esters dérivés de l’acide chloroformique. La chimie des N-oxydes hétérocycliques (pyridine et N-oxydes) a connu un important développement au cours des dernières années. L’objectif principal du présent travail est l’étude de l’action du métoxycarbonylchloride sur la pyridine et certains de ses dérivés. Après avoir trouvé les conditions optimales, de nouveaux composés à base de pyridine ont été synthétisés. En remplaçant l’ion chlorure par d’autres ions, les produits synthétisés ont été cristallisés avec un bon rendement. La structure des produits a été caractérisée à l’aide de la spectroscopie infra rouge et la résonnance magnétique nucléaire. Spécifiquement, l’influence de la basicité du noyau hétérocyclique sur les enthalpies de formation des sels produits a été étudiée. En conclusion, la réaction chimique de formation est exothermique avec ΔH° < 0 pour tous les sels étudiés. En utilisant les constantes de Hammett sur le noyau de la pyridine, l’étude a monté que ces chaleurs de réaction dépendent de la basicité du noyau hétérocyclique. En perspective on peut envisager une étude de l’influence de la basicité des différents noyaux pyridiniques sur les effets de conjugaison polaire directe sur le groupe azoté dans les sels N-méthoxycarbonyl-(oxy)-pyridiniums.Mots clés: Pyridine N-Oxyde, chloroformiates, synthèse, constante de Hammett. English Title: Study of the influence of basicity on the enthalpy of reaction of N-methoxycarbonyl- (oxy) -pyridinium salts Heterocycles are important, as well in the biological, medicinal and therapeutic fields (vitamins, hormones, antibiotics, etc.), as in the industrial and technological sector (corrosion inhibitors, dyes, stabilizing agents, pesticides, herbicides). Chloroformates or chlorocarbonates are esters derived from chloroformic acid. The chemistry of heterocyclic N-oxides (pyridine and N-oxides) has experienced significant development in recent years. The main objective of this work is to study the action of metoxycarbonylchloride on pyridine and some of its derivatives. After finding the optimal conditions, new pyridine-based compounds were synthesized. By replacing the chloride ion with other ions, the synthesized products have been crystallized with good yield. Specifically, the influence of the basicity of the heterocyclic nucleus on the enthalpies of salt formation produced has been studied. The enthalpies formation of salt produced have been determined. In conclusion, the chemical reaction of formation is exothermic with ΔH ° < 0 for all the salts studied. Using Hammett's constants on the pyridine nucleus, the study has shown that these reaction heats depend on the basicity of the heterocyclic nucleus. In perspective, we can study the influence of the basicity of the different pyridine rings on the effects of direct polar conjugation on the nitrogen group in the N-methoxycarbonyl- (oxy) -pyridinium salts.Keywords: Pyridine N-Oxide, chloroformates, synthesis, Hammett constant.

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Deeb, Ali, Medhat El-Mobayed, Abdel Naby Essawy, Adel Abd El-Hamid, and Atef Mohamid Abd El-Hamid. "Heterocyclic synthesis from 3-amino-4-cyanopyrazole." Collection of Czechoslovak Chemical Communications 55, no. 3 (1990): 728–33. http://dx.doi.org/10.1135/cccc19900728.

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3-Amino-4-cyanopyrazole I reacts with hydroxylamine and with hydrazine to yield 1H,6H-3-aminopyrazolo[3,4-c]pyrazole (III and IV). Diazotized IV couples with 2-naphthol to give the arylazo derivative VI which cyclizes to 9H-naphthol[2,1-e]pyrazolo[3',4':3,4]pyrazolo[5,1-c]-[1,2,4]triazine VII by means of acetic acid. The pyrazol-5-ylthiourea obtained from I and phenyl isothiocyanate undergoes base-catalyzed cyclization to give pyrazolo[3,4-d]pyrimidinethione derivative IX. Compound I reacts with cyclohexane in the presence of zinc chloride to give the tetrahydropyrazolo[3,4-b]quinoline derivative XI. The reaction of I with pyridine 1-oxide affords 4H,5H-pyrazolo[5',1':2,3] [1,2,4]triazolo[1,5-a]pyridine-3-carbonitrile XII.

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26

Bracher, Franz. "Dimethylformamide Acetals and Bredereck’s Reagent as Building Blocks in Natural Products Total Synthesis." Mini-Reviews in Organic Chemistry 17, no. 1 (January 27, 2020): 47–66. http://dx.doi.org/10.2174/1570193x16666181204122143.

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Dimethylformamide acetals and Bredereck’s reagent (tert-butoxy-bis(dimethylamino) methane) are versatile C1 building blocks due to their ability to undergo condensation reactions with CH-acidic methyl and methylene moieties. Subsequent modulation of the resulting condensation products enables the preparation of open-chain products like aldehydes, ketones, enones, enol ethers, methyl groups, and, most important in alkaloid total synthesis, the annulation of heterocyclic rings like pyridines, pyridine-N-oxides, bromopyridines, aminopyridines, aminopyrimidines, pyrroles and chromenones. In certain cases, these reagents can act as alkylating agents. The applications of these building blocks in natural products total synthesis are reviewed here.

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27

Abdelhamid, Abdou O., and Sobhi M. Gomha. "Synthesis of New Pyrazolo[1,5-a]pyrimidine, Triazolo[4,3-a]pyrimidine Derivatives, and Thieno[2,3-b]pyridine Derivatives from Sodium 3-(5-Methyl-1-phenyl-1H-pyrazol-4-yl)-3-oxoprop-1-en-1-olate." Journal of Chemistry 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/327095.

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Condensation of sodium 3-oxo-3-(1-phenyl-1H-pyrazol-4-yl)prop-1-en-1-olate (2) with several heterocyclic amines, cyanoacetamide, cyanothioacetamide, and 2-cyanoacetohydrazide gives pyrazolo[1,5-a]pyrimidines (5a–d), pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine (9), benzo[4,5]imidazo[1,2-a]pyrimidine (10), [1,2,4]triazolo[1,5-a]pyrimidine (11), and pyridine derivatives (12–14). Also, thieno[2,3-b]pyridines (15–18) were synthesized via pyridinethione (13) withα-halo ketones andα-halo ester. Structures of the newly synthesized compounds were elucidated by elemental analysis, spectral data, alternative synthetic routes, and chemical transformation whenever possible.

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28

Palacios, Laura, Andrea Di Giuseppe, Ricardo Castarlenas, Fernando J. Lahoz, Jesús J. Pérez-Torrente, and Luis A. Oro. "Pyridine versus acetonitrile coordination in rhodium–N-heterocyclic carbene square-planar complexes." Dalton Transactions 44, no. 12 (2015): 5777–89. http://dx.doi.org/10.1039/c5dt00182j.

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Experimental and theoretical studies on the factors that control the coordination chemistry of N-donor ligands in square-planar complexes of the type RhCl(NHC)L¹L² (NHC = N-heterocyclic carbene) are presented.

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29

Akishina, E. A., and Е. А. Dikusar. "Chemical modification of different compounds with nitrogen-containing heterocycles." Proceedings of the National Academy of Sciences of Belarus, Chemical Series 57, no. 3 (September 5, 2021): 356–84. http://dx.doi.org/10.29235/1561-8331-2021-57-3-356-384.

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Heterocyclic compounds have an extremely important practical application, since many heterocycles are the basis of the most valuable medicinal substances, both natural (vitamins, enzymes, alkaloids, etc.) and synthetic biologically active compounds. The work mainly considers the most relevant directions for various purposes drugs search by modifying known bioactive natural, organoelement and framework compounds with 1,2-azole, oxazole, oxadiazole, thiazole, triazole, pyridine, pyrimidine heterocycles over the past 10 years. Chemical modification makes it possible to increase the water solubility of the compounds, which is important when choosing the pathways for the most rational drug introduction into the body, to reduce the toxicity of the corresponding substances, to increase the breadth of the therapeutic action, and also to give new valuable medicinal properties, thus significantly expanding their application in medicine and agriculture.

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30

Rostek, Charles J., Horng-Jau Lin, David J. Sikora, Alan R. Katritzky, Wojciech Kuzmierkiewicz, and Navayath Shobana. "Novel Sulfur Vulcanization Accelerators Based on Mercapto-Pyridine, -Pyrazine, and -Pyrimidine." Rubber Chemistry and Technology 69, no. 2 (May 1, 1996): 180–202. http://dx.doi.org/10.5254/1.3538364.

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Abstract Sulfur vulcanization accelerators derived from 2-mercaptobenzothiazole (MBT) have been a staple for the rubber processing industry for over 65 years. Most noteworthy are the sulfenamide derivatives, which provide various combinations of scorch delay and cure rate, depending upon the basicity and steric nature of the sulfenamide N-substituent(s). While the effect of the amine moiety on benzothiazole sulfenamide accelerator performance has been well documented, the effect of the S-linked heterocyclic moiety of the sulfenamide has been investigated to a much lesser extent. Thus, to gain a better understanding of the role of the heterocycle, a variety of novel disulfides and sulfenamides based on pyridine have been synthesized and tested. The performance of the pyridine based accelerators have been compared to each other and to the various benzothiazole analogues. Until recently, the corresponding sulfenimides (compounds containing two divalent thiol moieties attached to an amine nitrogen ) seem to have received little attention in the rubber industry. Sulfenimides based on pyridine, pyrazine and pyrimidine have therefore also been synthesized and tested. The differences in preparation and vulcanization activity for the benzothiazole sulfenimides and sulfenamides are described, as well as some rudimentary differences which have appeared in the early stages of mechanistic work. It has been discovered in the course of this work that other heterocyclic thiols may be substituted for 2-mercaptobenzothiazole in the basic sulfenimide structure to gain advantages both in faster cure rate and extended scorch delay. The behavior of these novel sulfenimides in common rubber cure systems is presented together with representative physical properties of the rubber vulcanizates.

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31

Mahajan, Bharat Kumar, Navneet Kumar, Rohit Chauhan, Vimal Chandra Srivastava, and Siddhant Gulati. "Mechanistic evaluation of heterocyclic aromatic compounds mineralization by a Cu doped ZnO photo-catalyst." Photochemical & Photobiological Sciences 18, no. 6 (2019): 1540–55. http://dx.doi.org/10.1039/c8pp00580j.

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32

Riener, Korbinian, Alexander Pöthig, Mirza Cokoja, Wolfgang A. Herrmann, and Fritz E. Kühn. "Structure and spectroscopic properties of the dimeric copper(I) N-heterocyclic carbene complex [Cu2(CNCt-Bu)2](PF6)2." Acta Crystallographica Section C Structural Chemistry 71, no. 8 (July 7, 2015): 643–46. http://dx.doi.org/10.1107/s2053229615012140.

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In recent years, the use of copper N-heterocyclic carbene (NHC) complexes has expanded to fields besides catalysis, namely medicinal chemistry and luminescence applications. In the latter case, multinuclear copper NHC compounds have attracted interest, however, the number of these complexes in the literature is still quite limited. Bis[μ-1,3-bis(3-tert-butylimidazolin-2-yliden-1-yl)pyridine]-1κ4C2,N:N,C2′;2κ4C2,N:N,C2′-dicopper(I) bis(hexafluoridophosphate), [Cu2(C19H25N5)2](PF6)2, is a dimeric copper(I) complex bridged by two CNC,i.e.bis(N-heterocyclic carbene)pyridine, ligands. Each CuIatom is almost linearly coordinated by two NHC ligands and interactions are observed between the pyridine N atoms and the metal centres, while no cuprophilic interactions were observed. Very strong absorption bands are evident in the UV–Vis spectrum at 236 and 274 nm, and an emission band is observed at 450 nm. The reported complex is a new example of a multinuclear copper NHC complex and a member of a compound class which has only rarely been reported.

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33

Bisagni, Emile, Marilys Rautureau, Martine Croisy-Delcey, and Christiane Huel. "Nouvelle synthèse de chloro-1 méthyl-5 isoquinoléines fusionnées à divers systèmes aromatiques par leur liaison [g]." Canadian Journal of Chemistry 65, no. 9 (September 1, 1987): 2027–30. http://dx.doi.org/10.1139/v87-337.

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Lithiation of 4-acetyl 2-chloro pyridine ethylene glycol ketal by exchange with lithium diisopropylamine (LDA) led to 4-acetyl 2-chloro 3-lithio pyridine ethylene glycol ketal. This lithio derivative was reacted with aromatic aldehydes giving the expected alcohols, which were reduced by triethylsilane and trifluoroacetic acid at room temperature. The resulting 4-acetyl 3-arylmethyl 2-chloro pyridine ethylene glycol ketals were hydrolysed and cyclized in acidic medium, leading to polycondensed heterocyclic systems that have a 1-chloro 5-methyl isoquinoline nucleus fused by its [g] bond to the starting aromatic aldehyde.

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34

Ito, Hajime. "Copper-catalyzed asymmetric dearomative borylation: new pathway to optically active heterocyclic compounds." Pure and Applied Chemistry 90, no. 4 (March 28, 2018): 703–10. http://dx.doi.org/10.1515/pac-2017-0912.

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AbstractChiralN-heterocyclic organoboronates represent promising intermediates for the preparation of various bioactive and pharmaceutical compounds. We recently reported the first asymmetric dearomative borylation of indoles by copper-catalyzed borylation. Then we further developed dearomatization/enantioselective borylation sequence. Chiral 3-boryl-tetrahydropyridines and chiral boryl-tetrahydroquinolines via the copper(I)-catalyzed regio-, diastereo- and enantioselective borylation of 1,2-dihydropyridines and 1,2-dihydroquinilines, which were prepared by the partial reduction of the corresponding pyridine or quinoline derivatives. This dearomatization/enantioselective borylation procedures provide a direct access to chiral piperidines and tetrahydroquinolines from readily available pyridines or quinolines in combination with the stereospecific transformation of the stereogenic C–B bond.

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35

Rubino, Simona, Rosa Alduina, Patrizia Cancemi, Maria Assunta Girasolo, Vita Di Stefano, Santino Orecchio, Silvestre Buscemi, and Ivana Pibiri. "Mononuclear Perfluoroalkyl-Heterocyclic Complexes of Pd(II): Synthesis, Structural Characterization and Antimicrobial Activity." Molecules 25, no. 19 (September 30, 2020): 4487. http://dx.doi.org/10.3390/molecules25194487.

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Two mononuclear Pd(II) complexes [PdCl2(pfptp)] (1) and [PdCl2(pfhtp)] (2), with ligands 2-(3-perfluoropropyl-1-methyl-1,2,4-triazole-5yl)-pyridine (pfptp) and 2-(3-perfluoroheptyl-1-methyl-1,2,4-triazole-5yl)-pyridine (pfhtp), were synthesized and structurally characterized. The two complexes showed a bidentate coordination of the ligand occurring through N atom of pyridine ring and N4 atom of 1,2,4-triazole. Both complexes showed antimicrobial activity when tested against both Gram-negative and Gram-positive bacterial strains.

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36

S. Ibrahim, Nadia, Mona Hassan Mohamed, Nadia Sobhy Ibrahim, and Mohamed Hilmy Elnagdi. "Nitriles in Heterocyclic Synthesis: Synthesis of Some New Pyridine, Pyridazine, and Pyrimidine Derivatives." HETEROCYCLES 26, no. 4 (1987): 899. http://dx.doi.org/10.3987/r-1987-04-0899.

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37

Burstein, Christian, Christian W. Lehmann, and Frank Glorius. "Imidazo[1,5-a]pyridine-3-ylidenes—pyridine derived N-heterocyclic carbene ligands." Tetrahedron 61, no. 26 (June 2005): 6207–17. http://dx.doi.org/10.1016/j.tet.2005.03.115.

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38

Nikookar, Hamideh, Setareh Moghimi, Mohammad Hosein Sayahi, Mohammad Mahdavi, Parviz Rashidi Ranjbar, Loghman Firoozpour, and Alireza Foroumadi. "A Convenient Method for the Synthesis of Chromeno[4,3-b]pyridines Via Three-component Reaction." Combinatorial Chemistry & High Throughput Screening 21, no. 5 (July 20, 2018): 344–48. http://dx.doi.org/10.2174/1386207321666180524110635.

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Aim and Objective: The importance of Chromeno[4,3-b]pyridines in bioactive compounds, highlighted the ongoing research on developing novel methods for the construction of this heterocyclic scaffold. Regarding the advantageous features of multi-component reactions in organic synthesis, we will try to synthesize pyridocoumarins through this method. Materials and Methods: Chromeno[4,3-b]pyridines were conveniently prepared from a threecomponent condensation reaction between 4-hydroxy coumarin, ammonia and ethyl 2,4-dioxo-4- arylbutanoates in refluxing n-propanol. The synthesized compounds were characterized by NMR, IR and Mass spectroscopy. Results: The reaction proceeded through an in situ formed 4-amino coumarin, affording eight new target compounds in good yields. Conclusion: This method introduce a novel approach to ethyl 4-aryl-5-oxo-5H-chromeno[4,3- b]pyridine-2-carboxylate derivatives and allow organic chemists to prepare 4-aminocoumarin in reaction medium.

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39

Fang, Ming, and Bin Zhao. "Ln-Ag heterometallic coordination polymers." Reviews in Inorganic Chemistry 35, no. 2 (June 1, 2015): 81–113. http://dx.doi.org/10.1515/revic-2014-0009.

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AbstractThe last few years have seen an increasing interest in the study of lanthanide-silver (Ln-Ag) heterometallic coordination polymers due to their potential applications. It has led to intense activity of chemists to produce Ln-Ag heterometallic coordination polymers and investigate their properties. In this review, we summarize recent research development in the fascinating and challenging field of Ln-Ag heterometallic coordination polymers. This review covers 182 Ln-Ag heterometallic coordination polymers, which are categorized by the kind of ligand as N-heterocyclic carboxylate ligands and others. There are three categories of Ln-Ag coordination polymer based on N-heterocyclic carboxylate ligands: one dimensional (1D), 2D, and 3D. The 3D part was divided into Ln-Ag coordination polymers based on pyridine carboxylate ligands and other N-heterocyclic carboxylate ligands. This perspective illustrates the coordination features of compounds constructed by N-heterocyclic carboxylate ligands. Luminescent properties are also discussed.

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40

Stiborová, Marie, and Sylva Leblová. "Effect of heterocyclic compounds and 2-mercaptoethanol on rape alcohol dehydrogenase." Collection of Czechoslovak Chemical Communications 52, no. 8 (1987): 2107–13. http://dx.doi.org/10.1135/cccc19872107.

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Rape alcohol dehydrogenase (ADH) is inhibited by heterocyclic compounds with a five- to six-membered ring (imidazole, pyrazole, 4-methylpyrazole, 3-methylpyrazole, pyridine, nicotine amide) and by o-phenanthroline, a heterocyclic, polycyclic compound. Pyrazole and its derivatives, imidazole and pyridine, are competitive inhibitors with respect to ethanol. Nicotine amide and o-phenanthroline behave as mixed inhibitors (competitive – noncompetitive) with respect to the substrate. The addition of Zn2+-ions to the reaction medium interferes with the competition by o-phenanthroline. 4-Methylpyrazole and pyrazole are the strongest inhibitors of rape ADH. 2-Mercaptoethanol is an inhibitor of rape ADH which competes with ethanol and the coenzyme. The reversible inhibition by mercaptoethanol changes into the irreversible inactivation of the enzyme. The binding of inhibitors to the zinc atom present in the molecule of rape ADH and the localization of the metal in the enzyme protein have been studied.

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41

Fahmy, Sherif Mahmoud, and Rafat Milad Mohareb. "Activated Nitriles in Heterocyclic Synthesis: A Novel Synthesis of Pyridine and Pyridazine Derivatives." Synthesis 1985, no. 12 (1985): 1135–37. http://dx.doi.org/10.1055/s-1985-31451.

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42

Ilkin, Vladimir, Vera Berseneva, Tetyana Beryozkina, Tatiana Glukhareva, Lidia Dianova, Wim Dehaen, Eugenia Seliverstova, and Vasiliy Bakulev. "Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides." Beilstein Journal of Organic Chemistry 16 (December 1, 2020): 2937–47. http://dx.doi.org/10.3762/bjoc.16.243.

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N-Sulfonyl amidines bearing 1,2,3-triazole, isoxazole, thiazole and pyridine substituents were successfully prepared for the first time by reactions of primary, secondary and tertiary heterocyclic thioamides with alkyl- and arylsulfonyl azides. For each type of thioamides a reliable procedure to prepare N-sulfonyl amidines in good yields was found. Reactions of 1-aryl-1,2,3-triazole-4-carbothioamides with azides were shown to be accompanied with a Dimroth rearrangement to form 1-unsubstituted 5-arylamino-1,2,3-triazole-4-N-sulfonylcarbimidamides. 2,5-Dithiocarbamoylpyridine reacts with sulfonyl azides to form a pyridine bearing two sulfonyl amidine groups.

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43

Kassaee, M. Z., M. R. Momeni, F. A. Shakib, and M. Ghambarian. "Pyridine derived N-heterocyclic germylenes: A density functional perspective." Journal of Organometallic Chemistry 695, no. 5 (March 2010): 760–65. http://dx.doi.org/10.1016/j.jorganchem.2009.12.013.

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44

Sharma, Nidhi, Sanjeev Kumar, Sangit Kumar, S. K. Mehta, and K. K. Bhasin. "Synthesis and characterization of fused imidazole heterocyclic selenoesters and their application for chemical detoxification of HgCl2." New Journal of Chemistry 42, no. 4 (2018): 2702–10. http://dx.doi.org/10.1039/c7nj03908e.

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45

McKinnon, David M., Perry Spevack, and Graham Tipples. "Conversion of some azaheterocyclic-acetic esters and -acetonitriles into fused heterocycles." Canadian Journal of Chemistry 66, no. 9 (September 1, 1988): 2339–44. http://dx.doi.org/10.1139/v88-370.

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Various heterocyclic acetic esters and nitriles of the pyridine, thiazole, and imidazole series react with 3-methylthio-4-phenyl-1,2-dithiolium perchlorate to form fused pyridinethiones or dithiolylidene esters. These esters or nitriles also react with trichloromethanesulfenyl chloride to form fused isothiazoles.

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46

Karpov, Sergey, Arthur Grigor’ev, Yakov Kayukov, Iuliia Gracheva, and Victor Tafeenko. "Cascade Regioselective Heterocyclization of 2-Acyl-1,1,3,3-tetracyanopropenides: Synthesis of Pyrrolo[3,4-c]pyridine and Pyrrolo[3,4-d]thieno[2,3-b]pyridine Derivatives." Synlett 28, no. 13 (May 2, 2017): 1592–95. http://dx.doi.org/10.1055/s-0036-1588823.

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2-Acyl-1,1,3,3-tetracyanopropenides (ATCN) undergo cascade heterocyclization under the action of aliphatic thiols, resulting in the formation of 6-(alkylthio)-4-amino-1-aryl(alkyl)-1-hydroxy-3-oxo-2,3-dihydro-1H-pyrrolo[3,4-c]pyridine-7-carbonitriles. The involvement of methyl mercaptoacetate to this reaction leads to the formation of the methyl 4,8-diamino-1-aryl-1-hydroxy-3-oxo-2,3-dihydro-1H-pyrrolo[3,4-d]thieno[2,3-b]pyridine-7-carboxylates, containing a new fused heterocyclic scaffold.

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47

Tahir, Tehreem, Muhammad Ashfaq, Muhammad Saleem, Muhammad Rafiq, Mirza Imran Shahzad, Katarzyna Kotwica-Mojzych, and Mariusz Mojzych. "Pyridine Scaffolds, Phenols and Derivatives of Azo Moiety: Current Therapeutic Perspectives." Molecules 26, no. 16 (August 11, 2021): 4872. http://dx.doi.org/10.3390/molecules26164872.

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Synthetic heterocyclic compounds have incredible potential against different diseases; pyridines, phenolic compounds and the derivatives of azo moiety have shown excellent antimicrobial, antiviral, antidiabetic, anti-melanogenic, anti-ulcer, anticancer, anti-mycobacterial, anti-inflammatory, DNA binding and chemosensing activities. In the present review, the above-mentioned activities of the nitrogen-containing heterocyclic compounds (pyridines), hydroxyl (phenols) and azo derivatives are discussed with reference to the minimum inhibitory concentration and structure–activity relationship, which clearly indicate that the presence of nitrogen in the phenyl ring; in addition, the hydroxyl substituent and the incorporation of a diazo group is crucial for the improved efficacies of the compounds in probing different diseases. The comparison was made with the reported drugs and new synthetic derivatives that showed recent therapeutic perspectives made in the last five years.

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Wiley, Richard H. "Pyridine/acetic anhydride initiated polymerization of some heterocyclic acids." Journal of Polymer Science Part A: Polymer Chemistry 25, no. 2 (February 1987): 735–37. http://dx.doi.org/10.1002/pola.1987.080250226.

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49

Bognár, Balázs, Györgyi Úr, Cecília Sár, Olga H. Hankovszky, Kálmán Hideg, and Tamás Kálai. "Synthesis and Application of Stable Nitroxide Free Radicals Fused with Carbocycles and Heterocycles." Current Organic Chemistry 23, no. 4 (May 22, 2019): 480–501. http://dx.doi.org/10.2174/1385272823666190318163321.

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Stable nitroxide free radicals have traditionally been associated with 2,2,6,6- tetramethylpiperidine-1-oxyl (TEMPO) or its 4-substituted derivatives as relatively inexpensive and readily accessible compounds with limited possibilities for further chemical modification. Over the past two decades, there has been a resurgence of interest in stable free radicals with proper functionalization tuned for various applications. The objective of this review is to present recent results with synthetic methodologies to achieve stable nitroxide free radicals fused with aromatic carbocycles and heterocycles. There are two main approaches for accessing stable nitroxide free radicals fused with arenes, e.g., isoindoline- like nitroxides: further functionalization and oxidation of phthalimide or inventive functionalization of pyrroline nitroxide key compounds. The latter also offers the constructions of versatile heterocyclic scaffolds (furan, pyrrole, thiophene, 1,2-thiazole, selenophene, pyrazole, pyrimidine, pyridine, pyridazine, 1,5-benzothiazepine) that are fused with pyrroline or tetrahydropyridine nitroxide rings. The possible applications of these new stable nitroxide free radicals, such as covalent spin labels and noncovalent spin probes of proteins and nucleic acids, profluorescent probes, building blocks for construction of dual active drugs and electroactive materials, and substances for controlled free radical polymerization, are discussed.

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Kim, Jiyun, Hyungwoo Hahm, Ji Yeon Ryu, Seunghwan Byun, Da-Ae Park, Seoung Ho Lee, Hyunseob Lim, Junseong Lee, and Sukwon Hong. "Pyridine-Chelated Imidazo[1,5-a]Pyridine N-Heterocyclic Carbene Nickel(II) Complexes for Acrylate Synthesis from Ethylene and CO2." Catalysts 10, no. 7 (July 8, 2020): 758. http://dx.doi.org/10.3390/catal10070758.

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Nickel(II) dichloride complexes with a pyridine-chelated imidazo[1,5-a]pyridin-3-ylidene py-ImPy ligand were developed as novel catalyst precursors for acrylate synthesis reaction from ethylene and carbon dioxide (CO2), a highly promising sustainable process in terms of carbon capture and utilization (CCU). Two types of ImPy salts were prepared as new C,N-bidentate ligand precursors; py-ImPy salts (3, 4a–4e) having a pyridine group at C(5) on ImPy and a N-picolyl-ImPy salt (10) having a picolyl group at N atom on ImPy. Nickel(II) complexes such as py-ImPyNi(II)Cl2 (7, 8a–8e) and N-picolyl-ImPyNi(II)Cl2 (12) were synthesized via transmetalation protocol from silver(I) complexes, py-ImPyAgCl (5, 6a–6e) and N-picolyl-ImPyAgCl (11). X-ray diffraction analysis of nickel(II) complexes (7, 8b, 12) showed a monomeric distorted tetrahedral geometry and a six-membered chelate ring structure. py-ImPy ligands formed a more planar six-membered chelate with the nickel center than did N-picolyl-ImPy ligand. py-ImPyNi(II)Cl2 complexes (8a–8e) with tert-butyl substituents exhibited noticeable catalytic activity in acrylate synthesis from ethylene and CO2 (up to 108% acrylate). Interestingly, the use of additional additives including monodentate phosphines increased catalytic activity up to 845% acrylate (TON 8).

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Journal articles on the topic 'Heterocyclic chemistry : Pyridine'

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