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Journal articles on the topic 'Heterocyclic structures'

Author: Grafiati

Published: 24 April 2022

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1

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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2

Shekarkhand, Marzieh, Karim Zare, Majid Monajjemi, Elham Tazikeh-Lemeski, and Masoumeh Sayadian. "Computational study of heterocyclic anticancer compounds through nbo method." Nexo Revista Científica 35, no. 01 (April 6, 2022): 367–81. http://dx.doi.org/10.5377/nexo.v35i01.13982.

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In the present study NBO method contain the HOMO and the LUMO energies are calculated for 10 different heterocycles anticancer drug using B3LYP/6-31G(d,p). Frontier molecular orbitals (HOMO and LUMO) and Molecular Electrostatic Potential map of the compound was produced by using the π stacking of structures and anticancer activity of molecules. The NBO analysis was suggested that the molecular system contains π- π interaction, strong conjugative interactions and the molecule become more polarized owing to the movement of π-electron cloud from donor to acceptor. NBO, HOMO and LUMO energies, were investigated and Anticancer activity of Aromatic Heterocyclic compounds was investigated by NBO study and result was compared with our previous study about NICS and S-NICS of these 10 anticancer drug. the HOMO/LUMO gap of the heterocycle anticancer drug is significantly different from each other. The NBO method is used in both symmetric and asymmetric molecules and provides accurate information on the aromatics of the compound, especially the heterocyclic rings. It also provides accurate information in protected areas. Molecule 8 has the highest amount of HOMO and therefore aromaticity among the studied compounds which confirms the result of molecular orbital examination.

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3

Randić, Milan, Sonja Nikolić, and Nenad Trinajstić. "Aromaticity in heterocyclic molecules containing divalent sulfur." Collection of Czechoslovak Chemical Communications 53, no. 9 (1988): 2023–54. http://dx.doi.org/10.1135/cccc19882023.

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The conjugated circuits model is applied to heterocycles containing divalent sulfur. A novel parametrization is introduced for 4n + 2 and 4n conjugated circuits containing a single sulfur atom. The relative aromatic stabilities of a number of heterocyclic systems containing divalent sulfur are studied. Comparison is made whenever possible with earlier reported resonance energies of these compounds, obtained by using Huckel MO and SCF π-MO models, and appropriate reference structures. Special attention is given to positional isomers. An explanation of the differences amongst such isomers is given.

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4

Yu, Jie, Ya Zhou, Dian-Feng Chen, and Liu-Zhu Gong. "Organocatalytic asymmetric synthesis of chiral nitrogenous heterocycles and natural products." Pure and Applied Chemistry 86, no. 7 (July 22, 2014): 1217–26. http://dx.doi.org/10.1515/pac-2013-1208.

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AbstractNitrogen-containing chiral heterocycles represent important structural elements with wide occurrence in natural and unnatural compounds exhibiting important biological activities. Herein, we describe our recent endeavors directed toward the Brønsted acid-catalyzed 1,3-dipolar cycloaddition and alkylation reactions, together with the metal/Brønsted acid relay catalytic cascade reactions to access some typical nitrogenous heterocyclic structures and natural alkaloids, including (+)-folicanthine and (+)-gliocladin C.

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5

Höltzl, Tibor, Vu Thi Ngan, Minh Tho Nguyen, and Tamás Veszprémi. "Resonance structures of N-heterocyclic carbenes." Chemical Physics Letters 481, no. 1-3 (October 2009): 54–57. http://dx.doi.org/10.1016/j.cplett.2009.09.060.

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6

Drapak, І. V. "In silico screening of drug-like molecules for the treatment of cardiovascular diseases on the basis of five-membered privileged heterocycles." Farmatsevtychnyi zhurnal, no. 4 (September 10, 2019): 61–72. http://dx.doi.org/10.32352/0367-3057.4.19.07.

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Among various heterocyclic systems, the derivatives of five-membered heterocycles are of special interest. Most of the above mentioned heterocycles are treatred as so-called privileged structures in modern medicinal chemistry. In silico screening among five-membered heterocycles of molecules for the treatment of cardiovascular diseases is actual. The aim of the work was the search for synthetic drug-like molecules based on functionalized five-membered heterocycles and related heterocyclic systems as an element of the theoretical platform for rational design of compounds acting on the cardiovascular system, and prediction of their possible mechanism of action. The objects of the study were derivatives of uncondensed and condensed five-membered heterocycles. In the work, in silico approaches were applied using the programs: Hyper-Chem, PASS, AutoDock, PROTOX. Based on the previous studies, focused sub-libraries of small synthetic drug-like molecules based on functionalized five-membered heterocycles and related heterocyclic systems have been selected. The compounds were divided on 12 groups. The optimization of the compound structures, the drug-like parameters calculation were carried out. The activity prediction, the acute toxicity level and docking studies to probable bio-targets which are related with cardiovascular drug mechanism of action have been carried out. It was shown that thiazole and thiadiazole based compounds possessed the highest calculated affinity levels to selected bio-targets. This is consistent with PASS-based prediction data. Diverse functionalized derivatives of five-membered heterocycles (thiazole, thiazolidine, thiadiazole, pyrazole, thiophene, triazole) and related fused heterocycles have been grouped in focused sub-libraries of compounds. it has been established that thiazole and thiadiazole based compounds are promising objects for directed synthesis and further modification as potential cardiovascular agents based on the prediction of biological activity, the calculation of affinity to potent bio-targets, and the prediction of the drug-like features and acute toxicity level. The prognostic values of the parameters of the above mentioned groups of compounds may be used as the element of theoretical platform for the search and de novo design of potential drugs for the treatment of cardiovascular diseases.

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7

Lai, Pui-Mun, and Sie-Tiong Ha. "Synthesis of Heterocyclic Pyridine-Based Chalcones with Dimeric Structure." Chemistry & Chemical Technology 16, no. 1 (February 20, 2022): 1–6. http://dx.doi.org/10.23939/chcht16.01.001.

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Three new heterocyclic chalcones containing pyridine moiety were synthesized and their chemical structures were determined via IR, 1H NMR and 13C NMR spectroscopy. General name of these compounds are α,ω-bis{3-(pyridin-3-yl)-1-(phenyl-4-oxy)prop-2-en-1-one}alkanes. The chalcones are dimers having a symmetrical structure and they can be differed by the alkyl spacer length (CnH2n, where n = 8, 10 or 12). Differential scanning calorimetry (DSC) technique was employed to study their phase transition behaviors. DSC thermograms displayed direct isotropization and recrystallization during heating and cooling processes, respectively. The crystal phase turned into isotropic phase without exhibiting any mesophase. Influence of structure-liquid crystalline property relationships of the symmetrical dimers was examined in order to explain the reasons for the non-liquid crystalline properties in the current chalcones.

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8

Xu, Yuan, Li, and Li. "Recent Discovery of Heterocyclic Alkaloids from Marine-Derived Aspergillus Species." Marine Drugs 18, no. 1 (January 14, 2020): 54. http://dx.doi.org/10.3390/md18010054.

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Nitrogen heterocycles have drawn considerable attention due to of their significant biological activities. The marine fungi residing in extreme environments are among the richest sources of these basic nitrogen-containing secondary metabolites. As one of the most well-known universal groups of filamentous fungi, marine-derived Aspergillus species produce a large number of structurally unique heterocyclic alkaloids. This review attempts to provide a comprehensive summary of the structural diversity and biological activities of heterocyclic alkaloids that are produced by marine-derived Aspergillus species. Herein, a total of 130 such structures that were reported from the beginning of 2014 through the end of 2018 are included, and 75 references are cited in this review, which will benefit future drug development and innovation.

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9

Lynch, Daniel E., and Glyn D. Jones. "Geometry of the 2-aminoheterocyclic–carboxylic acid R 2 2(8) graph set: implications for crystal engineering." Acta Crystallographica Section B Structural Science 60, no. 6 (November 11, 2004): 748–54. http://dx.doi.org/10.1107/s0108768104023791.

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The geometry of the R_2^2(8) graph set formed between a 2-aminoheterocyclic ring containing an Nsp 2 atom (in the 1-position of the ring) and a carboxylic acid has been studied. Collating data from known co-crystal structures containing five- and six-membered heterocyclic rings from the Cambridge Structural Database revealed unexpected differences between two kinds of non-hydrogen contact distances, and between specific bond distances and angles of the heterocycle. Not only were the interatomic non-hydrogen distances between the N atoms (heterocycle) and O atoms (carboxylate) asymmetric, but also the 2-amino N atom (N21) to the heterocyclic C atom (C2) bond was shorter than the C2 to N1sp 2 bond. However, this shortening of the C2—N21 bond was not observed in the examples where N21 was substituted with a non-H atom. For the six-membered rings the data also showed that as the C2—N21 bond shortened the N1—C2—N21 bond angle increased.

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10

Harith M. Al-ajely. "Synthesis and pharmaceutical applications of Oxazine compounds derived from Pyronic, Salicylic, Antharanilic acids and Phenols." International Journal of Science and Research Archive 2, no. 2 (May 30, 2021): 074–86. http://dx.doi.org/10.30574/ijsra.2021.2.2.0250.

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It is well known from FDA reports that More than 75% of the heterocyclic compounds are drugs and 90 of heterocyclic compounds are cancer drugs. The nitrogen-based heterocycles occupy an exclusive position as a valuable source of therapeutic agents in medicinal chemistry. Most drugs approved by the FDA and currently available in the market are nitrogen-containing heterocyclic moieties, More over heterocyclic compounds are important class of organic chemistry due to their widely spread in nature. Also there are many route for their action and many mechanistic pathways for their preparation and different metabolic actions. This comes from the easily building or removal of any functional group within the molecules. Changing just on group cause to change the metabolic pathway of the drug action and site of attack of the desired target accordingly. This great characteristic value make them much more important in drug discovery programs of many researchers and also encouraged us and drew attentions of other researchers to develop new ways for their synthesis. As a result different pharmacological and medical applications. Oxazie compounds are sub branch of heterocyclic compounds. These compounds having two hetero atoms, Oxygen and nitrogen within their structures make them much more important toward therapeutic studies. We are here in our investigation will focus on the methodologies and the therapeutic action of the titled compounds as well as other various applications.

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11

Baumann, Marcus, Ian R. Baxendale, Steven V. Ley, and Nikzad Nikbin. "An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals." Beilstein Journal of Organic Chemistry 7 (April 18, 2011): 442–95. http://dx.doi.org/10.3762/bjoc.7.57.

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This review presents a comprehensive overview on selected synthetic routes towards commercial drug compounds as published in both journal and patent literature. Owing to the vast number of potential structures, we have concentrated only on those drugs containing five-membered heterocycles and focused principally on the assembly of the heterocyclic core. In order to target the most representative chemical entities the examples discussed have been selected from the top 200 best selling drugs of recent years.

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12

Reiche, J., B. Schulz, G. Knochenhauer, B. Dietzel, A. Freydank, T. Zetzsche, and L. Brehmer. "Supramolecular structures formed from heterocyclic aromatic molecules." Thin Solid Films 295, no. 1-2 (February 1997): 241–45. http://dx.doi.org/10.1016/s0040-6090(96)09391-1.

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13

Elguero, José. "Polymorphism and Desmotropy in Heterocyclic Crystal Structures." Crystal Growth & Design 11, no. 11 (November 2, 2011): 4731–38. http://dx.doi.org/10.1021/cg200970t.

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14

Ponikiewski, Lukasz, Weifeng Shi, and Alexander Rothenberger. "Synthesis and Structures of MetallatedN-Heterocyclic Derivatives." Zeitschrift für anorganische und allgemeine Chemie 634, no. 10 (August 2008): 1770–74. http://dx.doi.org/10.1002/zaac.200800044.

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15

Liang, Sen, and Cheng-Chu Zeng. "Organic electrochemistry: Anodic construction of heterocyclic structures." Current Opinion in Electrochemistry 24 (December 2020): 31–43. http://dx.doi.org/10.1016/j.coelec.2020.06.005.

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16

Böhm, Stanislav, Richard Kubík, Jiří Novotný, Jan Ondráček, Bohumil Kratochvíl, and Josef Kuthan. "Reinvestigation of heterocyclic structures: Oxidation products from 1-substituted 2,4,6-triphenylpyridinium salts." Collection of Czechoslovak Chemical Communications 56, no. 11 (1991): 2326–39. http://dx.doi.org/10.1135/cccc19912326.

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Ferricyanide oxidation of pyridinium salts Ia, Ib leads to mixture of isomeric heterocyclic ketones IIa, IIb and IVa, IVb, respectively. Crystal and molecular structures of the products IIb and IVb were determined by X-ray diffraction analysis. Formely presumed formation of heterocyclic systems type of the III type has been corrected.

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17

Bassam A. Hassan, Hameedi N Nasera, and Maitham M. Abdulridha. "Synthesis and antimicrobial evaluation of fused heterocyclic compound [1,2,4] triazolo [4,3-b][1,2,4,5] tetra zine." International Journal of Research in Pharmaceutical Sciences 10, no. 2 (April 14, 2019): 1254–58. http://dx.doi.org/10.26452/ijrps.v10i2.417.

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Nitrogen-containing, heterocycles, have special importance and vital, role in the discovery of effective bioactive, agents in the pharmaceutical, industry. The present article reports the synthesis of new fused, heterocycles triazolotetrazine by cyclo condensation, reaction as shown in scheme(1). The structures formula of synthesized compounds newly was evaluated by Ft-IR,1H-NMR spectrum, and C, H, N elemental analysis. Antimicrobial activity of triazolotetrazine studied against some pathogenic bacterial strains isolated from patients like Acinetobacter, Aeromonas, E. coli, Klebsiella, Staphylococcus, Streptococcus. Eventually, antibacterial of the fused heterocyclic compound was exhibited significant growth inhibition against some pathogenic bacteria which consider an important source of new antimicrobial compounds. The results, of such studies, are discussed in this paper.

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18

Ala, Paul J., Lucie Gonneville, Milton C. Hillman, Mary Becker-Pasha, Min Wei, Brian G. Reid, Ronald Klabe, et al. "Structural Basis for Inhibition of Protein-tyrosine Phosphatase 1B by Isothiazolidinone Heterocyclic Phosphonate Mimetics." Journal of Biological Chemistry 281, no. 43 (August 17, 2006): 32784–95. http://dx.doi.org/10.1074/jbc.m606873200.

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Crystal structures of protein-tyrosine phosphatase 1B in complex with compounds bearing a novel isothiazolidinone (IZD) heterocyclic phosphonate mimetic reveal that the heterocycle is highly complementary to the catalytic pocket of the protein. The heterocycle participates in an extensive network of hydrogen bonds with the backbone of the phosphate-binding loop, Phe182 of the flap, and the side chain of Arg221. When substituted with a phenol, the small inhibitor induces the closed conformation of the protein and displaces all waters in the catalytic pocket. Saturated IZD-containing peptides are more potent inhibitors than unsaturated analogs because the IZD heterocycle and phenyl ring directly attached to it bind in a nearly orthogonal orientation with respect to each other, a conformation that is close to the energy minimum of the saturated IZD-phenyl moiety. These results explain why the heterocycle is a potent phosphonate mimetic and an ideal starting point for designing small nonpeptidic inhibitors.

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19

Wang, Run, Xiong Xie, Hong Liu, and Yu Zhou. "Rh(III)-Catalyzed C–H Bond Activation for the Construction of Heterocycles with sp3-Carbon Centers." Catalysts 9, no. 10 (September 30, 2019): 823. http://dx.doi.org/10.3390/catal9100823.

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Rh(III)-catalyzed C–H activation features mild reaction conditions, good functional group tolerance, high reaction efficiency, and regioselectivity. Recently, it has attracted tremendous attention and has been employed to synthesize various heterocycles, such as indoles, isoquinolines, isoquinolones, pyrroles, pyridines, and polyheterocycles, which are important privileged structures in biological molecules, natural products, and agrochemicals. In this short review, we attempt to present an overview of recent advances in Rh(III)-mediated C–H bond activation to generate diverse heterocyclic scaffolds with sp3 carbon centers.

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20

Yuan, Shifang, Lijing Wang, Chuanbing Huang, Chunxia Niu, Kai Xiang, Caihong Xu, Gregory A. Solan, Hongwei Ma, and Wen-Hua Sun. "Azasilicon-bridged heterocyclic arylamines: syntheses, structures and photophysical properties." New Journal of Chemistry 42, no. 4 (2018): 3102–11. http://dx.doi.org/10.1039/c7nj03876c.

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The lithium κ¹-enamides undergo intermolecular cyclization reactions affording bis-azasilicon-bridged heterocyclic arylamines, which were hydrolysed to the saturated 1,4-diimines, and alternatively proceeded a redox reaction to afford the conjugated 1,4-diimines.

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21

Gupta, Vivek Kumar, Baljeet Kaur, Amandeep Kaur, Amanpreet Kaur, and Monika Gupta. "Synthesis and Biological Evaluation of 1,3,4-Oxadiazolyl benzenesulphonyl benzimidazole derivatives." Indian Journal of Pharmaceutical and Biological Research 6, no. 02 (June 30, 2018): 64–71. http://dx.doi.org/10.30750/ijpbr.6.2.10.

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Oxadiazoles are a class of heterocyclic aromatic chemical compound of azole family. Oxadiazole is five membered heterocycle having two carbons, two nitrogen, one oxygen and two double bonds. Oxadiazole exists in four isomeric forms depending upon the position of nitrogen atom in the ring. Benzimidazole is a heterocyclic aromatic compound. This bicyclic compound consists of fusion of benzene and imidazole. Benzimidazole may also be considered as cyclic analogues of imidines due to tautomerism effect. In the present study involves synthesis of1,3,4-oxadiazolyl benzenesulphonylbenzimidazole derivatives. All the synthesized compounds were screened against HepG-2 cell line to determine the growth inhibitory effect of compounds.All the synthesized compounds possessed good to moderate anti-cancer activity as compare to standard drug Adriamycin. Two of the synthesized compounds i.e. 8a and 8f were found to possess maximum anti-cancer activity.The structures of the synthesized compounds were established by IR and 1HNMR.

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22

Kederienė, Vilija, Indrė Jaglinskaitė, Paulina Voznikaitė, Jolanta Rousseau, Patrick Rollin, Algirdas Šačkus, and Arnaud Tatibouët. "Mild Copper-Catalyzed, l-Proline-Promoted Cross-Coupling of Methyl 3-Amino-1-benzothiophene-2-carboxylate." Molecules 26, no. 22 (November 11, 2021): 6822. http://dx.doi.org/10.3390/molecules26226822.

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Cu-catalyzed N-arylation is a useful tool for the chemical modification of aromatic heterocycles. Herein, an efficient carbon–nitrogen cross-coupling of methyl 3-amino-1-benzothiophene-2-carboxylate with a range of (hetero)aryl iodides using CuI, l-proline and Cs2CO3 in dioxane at moderate temperature is described. The procedure is an extremely general, relatively cheap, and experimentally simple way to afford the N-substituted products in moderate to high yields. The structures of the new heterocyclic compounds were confirmed by NMR spectroscopy and HRMS investigation.

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23

Su, Biyun, Yaning Li, Dandan Pan, Paison Faida, Tingyu Yan, and Zhan Qu. "Microwave Irradiation Syntheses and Crystal Structures of Two Series of Novel Fivemembered Heterocyclic Mono-Imine Compounds." Current Organic Synthesis 16, no. 3 (June 17, 2019): 444–48. http://dx.doi.org/10.2174/1570179416666181207125604.

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Aim and Objective: The late transition metal complexes with five-membered heterocyclic mono-imine ligands have attracted much attention because of their potential application in olefin polymerization catalysis. In order to increase the coordination ability of heteroatom N and S to center metals, CH3 group was introduced into the side arm of pyrrole imine and thiophene imine respectively, to get two series of novel five-membered heterocyclic imine compounds, mono(imino)pyrroles and mono(imino)thiophenes Materials and Methods: Two series of novel five-membered heterocyclic compounds with the mono-imine group were synthesized from the p-toluene sulfonic acid catalyzed Schiff base condensation of aromatic amines and 2-acetylpyrrole/ 2-acetylthiophene respectively, using CH3 group to substitute the common H atom on the side arm of pyrrole imine/ thiophene imine. Results: All the heterocyclic mono-imine compounds were characterized adequately by means of 1H NMR, 13C NMR, FT-IR, elementary analysis, as well as X-ray crystallographic diffraction. The reactivity differences between two precursor 2-acetylpyrrole and 2-acetylthiophene with aromatic amines were compared and discussed in detail. Conclusion: Compared to traditional heating methods, the solvent-free microwave irradiation seemed more efficient to prepare these series of five-membered heterocyclic mono-imine compounds, which resulted in a higher yield and cleaner product.

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24

Pittelkow, Michael, Thomas Hensel, Nicolaj Andersen, and Malene Plesner. "Synthesis of Heterocyclic [8]Circulenes and Related Structures." Synlett 27, no. 04 (December 22, 2015): 498–525. http://dx.doi.org/10.1055/s-0035-1560524.

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25

Barni, Ermanno, Piero Savarino, Raffaella Larovere, Guido Viscardi, and Ezio Pelizzetti. "Long chain heterocyclic dyes. Part one. Hydrophobic structures." Journal of Heterocyclic Chemistry 23, no. 1 (January 1986): 209–21. http://dx.doi.org/10.1002/jhet.5570230144.

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26

Li, H. M., X. Q. Liu, Z. Q. Wang, W. J. Fu, and C. Xu. "Crystal structures of two N-heterocyclic carbene-palladacycles." Journal of Structural Chemistry 56, no. 5 (September 2015): 1017–20. http://dx.doi.org/10.1134/s0022476615050303.

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27

M, Vijey Aanandhi, Ravichandiran V, and Prem Shankar Misra. "SYNTHETIC ROUTES AND NATURAL SOURCES OF 2-PYRIDONE DERIVATIVES AND THEIR PHARMACOLOGICAL ACTIVITY." Asian Journal of Pharmaceutical and Clinical Research 10, no. 7 (July 1, 2017): 87. http://dx.doi.org/10.22159/ajpcr.2017.v10i7.17989.

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Objective: 2-pyridone is a well-known heterocyclic ring having significant biological and medical application. The molecular structures and various activities of 2-pyridone derivatives as well as their syntheses and natural occurrence are analyzed and reviewed, and their reactivity toward various nucleophiles is discussed.Methods: 2-pyridone derivatives, first naturally obtained and described as early as before the 19th century, have been attracting increasing attention in view of their high reactivity as building blocks for the preparation of compounds of various classes due to their selective transformations with different reagents. Much information describing the natural occurrence, synthesis and the significant biological activity of 2-pyridone compounds are scattered throughout the literature. There are short chapters dealing with the synthesis and activity of 2-pyridone derivatives.Results: After compiling the above material, the abundance of certain heterocyclic ring and nature of typical chemical transformations applied in current drug synthesis. It is likely this results from the abundance of these heterocycles in natural products such as alkaloids and various synthetic derivatives revealing different biological activity. This might suggest a classical approach to drug design where substrate analogs gain inspiration from existing natural ligands.Conclusions: The data considered in this review clearly demonstrate the high synthetic potential of 2-pyridone derivatives. Many biologically active heterocyclic compounds have been obtained based on this heterocyclic ring. This suggests that 2-pyridone can be used in the design of novel highly effective pharmaceuticals with a broad spectrum of bioresponses.

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28

Guo, Meiyuan, Om Prakash, Hao Fan, Lisa H. M. de Groot, Valtýr Freyr Hlynsson, Simon Kaufhold, Olga Gordivska, et al. "HERFD-XANES probes of electronic structures of ironII/III carbene complexes." Physical Chemistry Chemical Physics 22, no. 16 (2020): 9067–73. http://dx.doi.org/10.1039/c9cp06309a.

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29

Yen, Swee Kuan, Lip Lin Koh, Han Vinh Huynh, and T. S. Andy Hor. "Structures and Suzuki-Coupling of N-Heterocyclic Carbene Complexes of PdII with Coordinated Solvent and PPh3." Australian Journal of Chemistry 62, no. 9 (2009): 1047. http://dx.doi.org/10.1071/ch09196.

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A series of mononuclear N,N-heterocyclic carbene (NNHC) complexes of PdII with mixed ligands of 1,3-dibenzylbenzimidazoly-2-ylidene and solvate (dimethyl sulfoxide, CH3CN, N,N-dimethylformamide, and pyridine) or PPh3 were prepared and characterized by X-ray single-crystal diffraction analysis. They are more active in the Suzuki–Miyaura coupling of selected aryl bromides than their N,S-heterocyclic carbene (NSHC) analogues.

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Liu, Mingxing, Jiarong Li, Shu Chen, Danfei Huang, Hongxin Chai, Qi Zhang, and Daxin Shi. "One-pot NHC-assisted access to 2,3-dihydropyrimido[4,5-d]pyrimidin-4(1H)-ones." RSC Adv. 4, no. 67 (2014): 35629–34. http://dx.doi.org/10.1039/c4ra05346j.

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An efficient N-heterocyclic carbene-assisted one-pot reaction synthesis of 2,3-dihydropyrimido[4,5-d] pyrimidin-4(1H)-ones from 2-(ethoxymethylene)malononitrile, guanidines (or amidines) and ketones (or aldehyde) has been developed. The novel method provides a highly efficient synthesis of pyrimido[4,5-d]pyrimidinering from materials with no heterocyclic structures.

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31

Dodds, Christopher A., Alan R. Kennedy, and Mark D. Spicer. "N-Heterocyclic Germylenes: Structural Characterisation of Some Heavy Analogues of the Ubiquitous N-Heterocyclic Carbenes." Heteroatom Chemistry 2019 (January 23, 2019): 1–8. http://dx.doi.org/10.1155/2019/9178371.

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The X-ray crystal structures of three N-heterocyclic germylenes (NHGes) have been elucidated including the previously unknown 1,3-bis(2,6-dimethylphenyl)diazagermol-2-ylidene (1). In addition, the X-ray crystal structures of the previously synthesised 1,3-bis(2,4,6-trimethylphenyl)diazagermol-2-ylidene (2) and 1,3-bis(2,6-diisopropylphenyl)diazagermol-2-ylidene (3) are also reported. The discrete molecular structures of compounds 1 to 3 are comparable, with Ge-N bond lengths in the range 1.835-1.875 Å, while the N-Ge-N bond angles range between 83.6 and 85.2°. Compound 2 was compared to the analogous N-heterocyclic carbene species, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). The major geometrical difference observed, as expected, was the bond angle around the divalent group 14 atom. The N-Ge-N bond angle was 83.6° for compound 2 versus the N-C-N bond angle of 101.4° for IMes. The Sn equivalent of (1), 1,3-bis(2,6-dimethylphenyl)diazastannol-2-ylidene (4), has also been synthesised and its crystal structure is reported here. In order to test their suitability as ligands, compounds 1 to 3 were reacted with a wide range of transition metal complexes. No NHGes containing metal complexes were observed. In all cases the NHGe either degraded or gave no reaction.

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32

Almashal, Faeza, Abeer Mohamed Jabar, and Adil Muala Dhumad. "Synthesis, characterization and DFT computational studies of new heterocyclic azo compounds." European Journal of Chemistry 9, no. 2 (June 30, 2018): 84–88. http://dx.doi.org/10.5155/eurjchem.9.2.84-88.1683.

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New heterocyclic azo compounds were prepared by coupling the diazonium salts with N-(4-methylphenyl)maleimide with various different sulfa compounds. The structure of heterocyclic azo compounds was determined by MS, FT-IR and 1H NMR techniques. The density function theory calculation at the B3LYP method with 6-311G(d,p) basis set is used to investigate the electronic structures of the prepared heterocyclic azo compounds. Mulliken charge distributions and HOMO-LUMO energies of the mentioned compounds have been also computed by same method and basis set.

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33

Guo, Yafei, and Syuzanna R. Harutyunyan. "Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents." Beilstein Journal of Organic Chemistry 16 (May 14, 2020): 1006–21. http://dx.doi.org/10.3762/bjoc.16.90.

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Copper-catalysed asymmetric C–C bond-forming reactions using organometallic reagents have developed into a powerful tool for the synthesis of complex molecules with single or multiple stereogenic centres over the past decades. Among the various acceptors employed in such reactions, those with a heterocyclic core are of particular importance because of the frequent occurrence of heterocyclic scaffolds in the structures of chiral natural products and bioactive molecules. Hence, this review focuses on the progress made over the past 20 years for heterocyclic acceptors.

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34

She, Zhe, Mina R. Narouz, Christene A. Smith, Amy MacLean, Hans-Peter Loock, Heinz-Bernhard Kraatz, and Cathleen M. Crudden. "N-Heterocyclic carbene and thiol micropatterns enable the selective deposition and transfer of copper films." Chemical Communications 56, no. 8 (2020): 1275–78. http://dx.doi.org/10.1039/c9cc08919e.

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35

Abbasi, Muhammad, Muhammad Ramzan, A. Aziz-Ur-Rehman, Sabahat Siddiqui, Mubashir Hassan, Hussain Raza, Syed Shah, Bushra Mirza, and Sung-Yum Seo. "Structure-activity relationship and in silico study of unique bi-heterocycles: 5-[(2-amino-1,3-thiazol-4-yl)methyl]-1,3,4-oxadiazole-2-thiol derivatives." Journal of the Serbian Chemical Society 84, no. 7 (2019): 649–61. http://dx.doi.org/10.2298/jsc180203019a.

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This paper presents the synthesis of some unique bi-heterocyclic hybrid molecules with a thiazole and an oxadiazole ring. The synthesis was initiated by the conversion of ethyl 2-(2-amino-1,3-thiazol-4-yl)acetate (1) to the corresponding 2-(2-amino-1,3-thiazol-4-yl)acetohydrazide (2) by the reaction with hydrazine hydrate in methanol. The treatment of the acid hydrazide, 2, with carbon disulfide gave the bi-heterocyclic nucleophile, 5-[(2-amino-1,3- -thiazol-4-yl)methyl]-1,3,4-oxadiazole-2-thiol (3). Finally, the target compounds, 5a?o, were synthesized by stirring the nucleophile 3 with different electrophiles, 4a?o, in DMF using LiH as a base and an activator. The structures of the newly synthesized molecules were confirmed through spectroscopic techniques, such as IR, EI-MS, 1H-NMR and 13C-NMR. The structure? ?activity relationship of all these bi-heterocycles was established by evaluating them against four enzymes, namely, acetylcholinesterase, butyrylcholinesterase, urease and ?-glucosidase, followed by their in silico study. Moreover, their cytotoxicity was also profiled by killing data of brine shrimps at various concentrations.

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36

Förstera, Daniela, Ingo Hartenbach, Martin Nieger, and Dietrich Gudat. "On the Synthesis and Addition Reactions of Chiral N-Heterocyclic Diphosphines." Zeitschrift für Naturforschung B 67, no. 8 (August 1, 2012): 765–73. http://dx.doi.org/10.5560/znb.2012-0177.

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Reaction of chiral N-heterocyclic chlorophosphines with lithium diphenylphosphide or of achiral N-heterocyclic chlorophosphines with optically active lithium menthyl phosphide produces chiral N-heterocyclic diphosphines which can be utilized in subsequent diphosphination reactions with activated alkenes or alkynes. The reaction with alkynes proceeds stereospecifically to produce Zethylene- 1,2-bisphosphines which are readily converted to nickel(II) or palladium(II) complexes. Reactions with alkenes are synthetically less useful as the addition proceeds without any chiral induction at the newly formed stereocenters to yield inseparable mixtures of diastereomeric products. The molecular structures of chiral Z-ethylene-1,2-bisphosphine complexes and of a chiral N-heterocyclic chlorophosphine have been determined by single-crystal X-ray diffraction

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37

Pozzo, Jean-Luc, André Samat, Robert Guglielmetti, Vladimir Lokshin, and Vladimir Minkin. "Furo-fused 2H-chromenes: synthesis and photochromic properties." Canadian Journal of Chemistry 74, no. 9 (September 1, 1996): 1649–59. http://dx.doi.org/10.1139/v96-182.

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New photochromic chromenes annulated with a furan ring have been synthesized. Thus, suitable heterocyclic phenols react with different propargylic alcohols in acidic medium to give the corresponding ethers, which cyclize into benzopyrans by thermal Claisen rearrangement. This synthetic approach was found to lead to a mixture of linear and angular chromenes that is strictly related to the nature of the phenol. However, regiospecificity could be obtained by reacting β-phenylcinnamaldehyde, in refluxing aprotic nonpolar solvents, with titanium(IV) salts of the former phenols. Electrocyclization of intermediately generated o-quinoid structures occurs on the α position towards the heterocyclic junction. All compounds exhibit photochromic behavior at room temperature. Furo-fused benzopyrans are particularly interesting with respect to naphthopyran parents in view of the bathochromically shifted and broadened absorption spectra of photoinduced forms. This trend is confirmed by the spectral data of several heterocyclospiro(7H-furo[3,2-f] chromenes). The achievable color depends significantly on the relative position of annulation on the chromenic moiety and substitution on the sp3 carbon atom. Key words: photochromism, heterocycle, regiospecificity, 2H-chromene, furan.

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38

Wu, Su-Min, Xiao-Yang Qiu, Shu-Juan Liu, and Juan Sun. "Single Heterocyclic Compounds as Monoamine Oxidase Inhibitors: From Past to Present." Mini-Reviews in Medicinal Chemistry 20, no. 10 (May 27, 2020): 908–20. http://dx.doi.org/10.2174/1389557520666200302114620.

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Inhibitors of monoamine oxidase (MAO) have shown therapeutic values in a variety of neurodegenerative diseases such as depression, Parkinson’s disease and Alzheimer’s disease. Heterocyclic compounds exhibit a broad spectrum of biological activities and vital leading compounds for the development of chemical drugs. Herein, we focus on the synthesis and screening of novel single heterocyclic derivatives with MAO inhibitory activities during the past decade. This review covers recent pharmacological advancements of single heterocyclic moiety along with structure- activity relationship to provide better correlation among different structures and their receptor interactions.

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39

Döndas, H., María de Gracia Retamosa, and José Sansano. "Current Trends towards the Synthesis of Bioactive Heterocycles and Natural Products Using 1,3-Dipolar Cycloadditions (1,3-DC) with Azomethine Ylides." Synthesis 49, no. 13 (June 7, 2017): 2819–51. http://dx.doi.org/10.1055/s-0036-1588423.

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This review summarizes the trends in the formation of complex or not so complex heterocyclic structures through 1,3-dipolar cycloadditions of azomethine ylides. Diastereo- and enantioselective processes as well as non-asymmetric cycloadditions constitute very important synthetic tools for achieving these compounds. This review covers the literature from 2015 through 2016 and organizes the research in terms of biologically important heterocycles and natural products from cascade 1,3-dipolar cycloadditions of azomethine ylides to the simpler forms of 1,3-dipolar cycloaddition.1 Introduction2 Synthesis of Spirooxindoles3 Synthesis of Spiropyrrolidines4 Synthesis of Spiropiperidines and Piperidines5 Synthesis of Pyrrolidines and Fused Pyrrolidines6 Synthesis of Pyrrolizidines and Indolizidines7 Synthesis of Quinolone and Isoquinolines8 Conclusions

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40

Jiang, Yangye, Kun Xu, and Chengchu Zeng. "Use of Electrochemistry in the Synthesis of Heterocyclic Structures." Chemical Reviews 118, no. 9 (October 17, 2017): 4485–540. http://dx.doi.org/10.1021/acs.chemrev.7b00271.

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41

Herrmann, Wolfgang A., Jan Schütz, Guido D. Frey, and Eberhardt Herdtweck. "N-Heterocyclic Carbenes: Synthesis, Structures, and Electronic Ligand Properties†,‡." Organometallics 25, no. 10 (May 2006): 2437–48. http://dx.doi.org/10.1021/om0600801.

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42

Kilián, Petr, Pavel Pazdera, Jaromír Marek, Josef Novosad, and Jiří Toužín. "New Heterocyclic Organophosphorus-Sulfur-Nitrogen Compounds, Syntheses and Structures." Zeitschrift für anorganische und allgemeine Chemie 624, no. 9 (September 1998): 1497–502. http://dx.doi.org/10.1002/(sici)1521-3749(199809)624:9<1497::aid-zaac1497>3.0.co;2-e.

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43

Seredina, M. A. "Thermochemical Transformations of Fibers with Aromatic and Heterocyclic Structures." Fibre Chemistry 51, no. 4 (November 2019): 217–19. http://dx.doi.org/10.1007/s10692-020-10078-w.

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44

De Silva, Chamila C., and Thomas A. Holme. "Computational studies of dative bond containing heterocyclic ring structures." Computational and Theoretical Chemistry 1019 (September 2013): 78–84. http://dx.doi.org/10.1016/j.comptc.2013.06.022.

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45

Vessally, Esmail, Somayeh Soleimani-Amiri, Akram Hosseinian, Ladan Edjlali, and Ahmadreza Bekhradnia. "New protocols to access imidazoles and their ring fused analogues: synthesis from N-propargylamines." RSC Advances 7, no. 12 (2017): 7079–91. http://dx.doi.org/10.1039/c6ra25816f.

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46

Ibrahim, Mohamed N., Mohamed F. El-Messmary, and Mohamed G. A. Elarfi. "Synthesis of Spiro Heterocyclic Compounds." E-Journal of Chemistry 7, no. 1 (2010): 55–58. http://dx.doi.org/10.1155/2010/604549.

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Reaction of isatin with acetophenone derivatives gave 3-hydroxy-3-phenacyl oxindole derivatives(II), dehydration of(II)gave 3-phenacylidene-2-indolinone derivatives(III). Condensation of(III)with hydrazine hydrate, phenylhydrazine and phenylthiourea afforded new spiropyrazolines(IV & V)and spiropyrimidinethione(VI)respectively. The structures of the final products were established by physical and spectral means.

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47

Chen, Qiaonan, Xiao Liang, Jiahui Du, Zhonglin Wei, Yu-Mo Zhang, Ting Zhang, Tianyou Qin, Wenbin Gao, Lan Sheng, and Sean Xiao-An Zhang. "Construction of highly fluorescent N–O seven-membered heterocyclesviathermo-oxidation of oxazolidines." Journal of Materials Chemistry C 7, no. 26 (2019): 8045–52. http://dx.doi.org/10.1039/c9tc01199d.

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48

Pawlowski, Robert, Filip Stanek, and Maciej Stodulski. "Recent Advances on Metal-Free, Visible-Light- Induced Catalysis for Assembling Nitrogen- and Oxygen-Based Heterocyclic Scaffolds." Molecules 24, no. 8 (April 18, 2019): 1533. http://dx.doi.org/10.3390/molecules24081533.

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Heterocycles are important class of structures, which occupy a major space in the domain of natural and bioactive compounds. For this reason, development of new synthetic strategies for their controllable synthesis became of special interests. The development of novel photoredox systems with wide-range application in organic synthesis is particularly interesting. Organic dyes have been widely applied as photoredox catalysts in organic synthesis. Their low costs compared to the typical photocatalysts based on transition metals make them an excellent alternative. This review describes proceedings since 2015 in the area of application of metal-free, visible-light-mediated catalysis for assembling various heterocyclic scaffolds containing five- and six-membered rings bearing nitrogen and oxygen heteroatoms.

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Chanderiya, Aayushi, Gowhar A. Naikoo, Ratnesh Das, Israr U. Hassan, Sushil K. Kashaw, and Sadanand Pandey. "Recent Advances in Metal Nanoparticles for the Synthesis of N-Containing Heterocyclic Compounds." Asian Journal of Chemistry 33, no. 5 (2021): 949–55. http://dx.doi.org/10.14233/ajchem.2021.23140.

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Heterocyclic compounds are indispensable organic structures because of their promising potential applications in medicinal, pharmaceutical and other related fields of chemistry. Exploring these heterocyclic compounds by evaluating metal nanoparticles as efficient nanocatalysts have attracted the researchers over the past decades, due to their stability, recyclability, reusability rather than conventional catalysts. Most of the nano-catalyzed organic reactions are taking place in benign and under green conditions. In this mini-review, we have documented synthesis of some of the recent N-containing heterocyclic compounds by utilizing advanced nanoparticles as effective catalysts. It has been concluded that exercising these nanocatalysts for the synthesis of N-containing heterocyclic compounds not only enhanced the yield of the product but has extensively increased the selectivity of the desired products via greener approach.

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Zhang, Min, Yi Gong, Wei Zhou, Ying Zhou, and Xiong-Li Liu. "Recent advances of chromone-based reactants in the catalytic asymmetric domino annulation reaction." Organic Chemistry Frontiers 8, no. 14 (2021): 3968–89. http://dx.doi.org/10.1039/d1qo00269d.

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