Artículos de revistas: "Heterocycles"

1

Zhu, Yannan y You Huang. "Organocatalyzed [3+3] Annulations for the Construction of Heterocycles". Synthesis 52, n.º 08 (5 de febrero de 2020): 1181–202. http://dx.doi.org/10.1055/s-0039-1690810.

Texto completo

Resumen

Six-membered heterocyclic systems are widely distributed in many natural products and pharmaceuticals, and the construction of highly functionalized six-membered heterocyclic compounds is an important topic in modern organic synthesis. Organocatalyzed [3+3] annulations represents an important method for assembling a substantial variety of six-membered cycles that contain one or more heteroatoms. This review describes the development of organocatalyzed [3+3] annulations for the synthesis of six-membered heterocycles, including organocatalysis using secondary amines, tertiary amines, phosphines, chiral phosphoric acids and N-heterocyclic carbenes.1 Introduction2 Secondary Amine Catalyzed [3+3] Annulations2.1 Synthesis of Nitrogen Heterocycles2.2 Synthesis of Oxygen Heterocycles2.3 Synthesis of Sulfur Heterocycles3 Tertiary Amine Catalyzed [3+3] Annulations3.1 Catalysis through Multiple Hydrogen-Bonding Interactions3.2 Catalysis of Tertiary Amines as Lewis Bases4 Phosphine-Catalyzed [3+3] Annulations4.1 Synthesis of Nitrogen Heterocycles4.2 Synthesis of Oxygen Heterocycles4.3 Synthesis of Heterocycles Containing Two or More Heteroatoms5 Chiral Phosphoric Acid Catalyzed [3+3] Annulations5.1 Synthesis of Nitrogen Heterocycles5.2 Synthesis of Heterocycles Containing Two or More Heteroatoms6 N-Heterocyclic Carbene Catalyzed [3+3] Annulations6.1 Synthesis of Nitrogen Heterocycles6.2 Synthesis of Oxygen Heterocycles6.3 Synthesis of Heterocycles Containing Two or More Heteroatoms7 Conclusion and Outlook

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Andres, C. J., Derek J. Denhart, Milind S. Deshpande y Kevin W. Gillman. "Recent Advances in the Solid Phase Synthesis of Drug Heterocyclic Small Molecules". Combinatorial Chemistry & High Throughput Screening 2, n.º 4 (agosto de 1999): 191–210. http://dx.doi.org/10.2174/1386207302666220204193145.

Texto completo

Resumen

Abstract: Because of their synthetic challenge, broad range of physical I chemical properties, and diverse biological activities, heterocycles continue to be of interest to both the academic and industrial chemist. This review covers recent advances in the solid phase synthesis of drug-like heterocyclic small molecules. Syntheses which form the heterocycle on the solid phase are emphasized; syntheses in which a preformed heterocycle is functionalized on the solid support have been omitted. The majority of references are from publication year 1999. This review should be of interest to anyone involved in, or contemplating the solid phase synthesis of small molecule drug-like heterocycles, especially for combinatorial chemistry applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Luna, Isadora Silva, Rayssa Marques Duarte da Cruz, Ryldene Marques Duarte da Cruz, Rodrigo Santos Aquino de Araújo y Francisco Jaime Bezerra Mendonça-Junior. "1,4-Dithiane-2,5-diol: A Versatile Synthon for the Synthesis of Sulfur-containing Heterocycles". Current Organic Synthesis 15, n.º 8 (17 de diciembre de 2018): 1026–42. http://dx.doi.org/10.2174/1570179415666180821154551.

Texto completo

Resumen

Background: 1,4-Dithiane-2,5-diol (1,4-DTD) is the stable dimer of α-mercapto acetaldehyde. This commercially available ambidentade compound is characterized as having in its chemical structure one group that acts as an electrophile and another that acts as a nucleophile, this permits its use as versatile and efficient synthon in synthetic heterocycle procedures. Objective: The aim of this review is to present synthetic applications of 1,4-DTD in heterocyclic chemistry and their applicability to the synthesis of bioactive compounds. Conclusion: Gewald reactions to obtain C-4 and C-5 unsubstituted 2-amino-thiophene derivatives; sulfa- Michael/Henry and sulfa-Michael/aldol sequences to obtain polysubstituted tetrahydrothiophenes, and other heterocyclic reactions that allow synthesizing several functionalized sulfur-containing heterocycles such as thiazolidines, oxathiazinoles and thiazoles are presented and discussed. The use of such heterocyclics in subsequent reactions allows obtaining various bioactive compounds including the antiretroviral lamivudine which is one of the examples presented in this review.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Winne, Johan, Jan Hullaert, Bram Denoo, Mien Christiaens y Brenda Callebaut. "Heterocycles as Moderators of Allyl Cation Cycloaddition Reactivity". Synlett 28, n.º 18 (27 de julio de 2017): 2345–52. http://dx.doi.org/10.1055/s-0036-1588511.

Texto completo

Resumen

For the rapid elaboration of polycarbocyclic scaffolds, prevalent in many important families of terpenoid natural products, allyl cations derived from simple heterocyclic alcohols can be used as versatile reaction partners in both (4+3) and (3+2) cycloaddition pathways. Our recent progress in this area is outlined, pointing towards the untapped potential of heterocycles to act as reagents in novel or known but challenging organic transformations.1 Heterocyclic Reagents2 Cycloadditions and Allyl Cations3 Furfuryl Cations in Cycloadditions4 Heterocycle-Substituted Cations in Cycloadditions5 Mechanistic Considerations6 Conclusions and Outlook

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Rusu, Aura, Ioana-Maria Moga, Livia Uncu y Gabriel Hancu. "The Role of Five-Membered Heterocycles in the Molecular Structure of Antibacterial Drugs Used in Therapy". Pharmaceutics 15, n.º 11 (29 de octubre de 2023): 2554. http://dx.doi.org/10.3390/pharmaceutics15112554.

Texto completo

Resumen

Five-membered heterocycles are essential structural components in various antibacterial drugs; the physicochemical properties of a five-membered heterocycle can play a crucial role in determining the biological activity of an antibacterial drug. These properties can affect the drug’s activity spectrum, potency, and pharmacokinetic and toxicological properties. Using scientific databases, we identified and discussed the antibacterials used in therapy, containing five-membered heterocycles in their molecular structure. The identified five-membered heterocycles used in antibacterial design contain one to four heteroatoms (nitrogen, oxygen, and sulfur). Antibacterials containing five-membered heterocycles were discussed, highlighting the biological properties imprinted by the targeted heterocycle. In some antibacterials, heterocycles with five atoms are pharmacophores responsible for their specific antibacterial activity. As pharmacophores, these heterocycles help design new medicinal molecules, improving their potency and selectivity and comprehending the structure-activity relationship of antibiotics. Unfortunately, particular heterocycles can also affect the drug’s potential toxicity. The review extensively presents the most successful five-atom heterocycles used to design antibacterial essential medicines. Understanding and optimizing the intrinsic characteristics of a five-membered heterocycle can help the development of antibacterial drugs with improved activity, pharmacokinetic profile, and safety.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Slivka, Mikhailo y Mikhailo Onysko. "The Use of Electrophilic Cyclization for the Preparation of Condensed Heterocycles". Synthesis 53, n.º 19 (19 de mayo de 2021): 3497–512. http://dx.doi.org/10.1055/s-0040-1706036.

Texto completo

Resumen

AbstractCondensed heterocycles are well-known for their excellent biological effects and they are undeniably important compounds in organic chemistry. Electrophilic cyclization reactions are widely used for the synthesis of mono-heterocyclic compounds. This review highlights the utility of electrophilic cyclization reactions as an effective generic tool for the synthesis of various condensed heterocycles containing functional groups that are able to undergo further chemical transformations, such as nucleophilic substitution, elimination, re-cyclization, cleavage, etc. This review describes the reactions of unsaturated derivatives of different heterocycles with various electrophilic agents (halogens, arylsulfanyl chlorides, mineral acids) resulting in annulation of an additional partially saturated heterocycle. The electrophilic reaction conditions, plausible mechanisms and the use of such transformations in organic synthesis are also discussed. The review mainly focuses on research published since 2002 in order to establish the current state of the art in this area. 1 Introduction2 Electrophilic Cyclization Pathways Involving a Nitrogen Nucleophilic Center3 Electrophilic Cyclization Pathways Involving a Chalcogen Nucleophilic Center3.1 Sulfur Centers3.2 Oxygen Centers3.3 Selenium Centers4 Strategies and Mechanisms5 Conclusion

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Cui, Hai-Lei. "Recent Advances in DMSO-Based Direct Synthesis of Heterocycles". Molecules 27, n.º 23 (2 de diciembre de 2022): 8480. http://dx.doi.org/10.3390/molecules27238480.

Texto completo

Resumen

Besides serving as a low-toxicity, inexpensive and easily accessible solvent, dimethyl sulfoxide (DMSO) has also been extensively used as a versatile reagent for the synthesis of functionalized molecules. Dimethyl sulfoxide can not only be utilized as a carbon source, a sulfur source and an oxygen source, but also be employed as a crucial oxidant enabling various transformations. The past decade has witnessed a large number of impressive achievements on the direct synthesis of heterocycles as well as modifications of heterocyclic compounds by applying DMSO as a reagent. This review summarized the DMSO-based direct heterocycle constructions from 2012 to 2022.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Ābele, E., R. Ābele, Ļ. Golomba, J. Višņevska, T. Beresņeva y K. Rubina. "Oximes of Seven-Membered Heterocyclic Compounds Containing One Heteroatom". Latvian Journal of Chemistry 50, n.º 3-4 (1 de enero de 2011): 205–22. http://dx.doi.org/10.2478/v10161-011-0071-7.

Texto completo

Resumen

Oximes of Seven-Membered Heterocyclic Compounds Containing One Heteroatom Literature data on the synthesis and structure of azepane, oxepane and thiepane oximes were reviewed. Synthesis of novel heterocycles from oximes of seven-membered heterocycles containing one heteroatom were described. Biological activity of oximes of seven-membered heterocycles with one heteroatom was also reviewed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Lechel, Tilman y Hans-Ulrich Reissig. "Synthesis of heterocycles via alkoxyallenes". Pure and Applied Chemistry 82, n.º 9 (31 de mayo de 2010): 1835–44. http://dx.doi.org/10.1351/pac-con-09-09-06.

Texto completo

Resumen

Lithiated alkoxyallenes are very versatile components for the synthesis of heterocycles such as furans, pyrroles, and 1,2-oxazines, easily allowing the preparation of natural products via these heterocyclic intermediates. A surprising three-component synthesis of N-acylated enaminones allowed the synthesis of highly functionalized 4-hydroxypyridines, 5-acetyloxazoles, and pyrimidines. All these heterocyclic products are ready for further functionalizations, in particular for palladium-catalyzed reactions, leading to libraries of new interesting heterocycles.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Ābele, E. "Oximes of Seven-Membered Heterocyclic Compounds Containing Two Heteroatoms". Latvian Journal of Chemistry 51, n.º 1-2 (1 de enero de 2012): 83–92. http://dx.doi.org/10.2478/v10161-012-0005-z.

Texto completo

Resumen

Oximes of Seven-Membered Heterocyclic Compounds Containing Two Heteroatoms Literature data concerning the synthesis and structure of diazepane, oxazepane and thiazepane oximes were reviewed. Synthesis of novel heterocycles from the oximes of seven-membered heterocycles containing two heteroatoms was described. Biological activity of oximes of seven-membered heterocycles with two heteroatoms was also reviewed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Egbujor, Melford C., Paolo Tucci, Ugomma C. Onyeije, Chigbundu N. Emeruwa y Luciano Saso. "NRF2 Activation by Nitrogen Heterocycles: A Review". Molecules 28, n.º 6 (18 de marzo de 2023): 2751. http://dx.doi.org/10.3390/molecules28062751.

Texto completo

Resumen

Several nitrogen heterocyclic analogues have been applied to clinical practice, and about 75% of drugs approved by the FDA contain at least a heterocyclic moiety. Thus, nitrogen heterocycles are beneficial scaffolds that occupy a central position in the development of new drugs. The fact that certain nitrogen heterocyclic compounds significantly activate the NRF2/ARE signaling pathway and upregulate the expression of NRF2-dependent genes, especially HO-1 and NQO1, underscores the need to study the roles and pharmacological effects of N-based heterocyclic moieties in NRF2 activation. Furthermore, nitrogen heterocycles exhibit significant antioxidant and anti-inflammatory activities. NRF2-activating molecules have been of tremendous research interest in recent times due to their therapeutic roles in neuroinflammation and oxidative stress-mediated diseases. A comprehensive review of the NRF2-inducing activities of N-based heterocycles and their derivatives will broaden their therapeutic prospects in a wide range of diseases. Thus, the present review, as the first of its kind, provides an overview of the roles and effects of nitrogen heterocyclic moieties in the activation of the NRF2 signaling pathway underpinning their antioxidant and anti-inflammatory actions in several diseases, their pharmacological properties and structural–activity relationship are also discussed with the aim of making new discoveries that will stimulate innovative research in this area.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Yadav, Shailendra, Sushma Singh y Chitrasen Gupta. "A CONCISE OVERVIEW ON HETEROCYCLIC COMPOUNDS EXHIBITING PESTICIDAL ACTIVITIES". International Journal of Advanced Research 9, n.º 08 (31 de agosto de 2021): 989–1004. http://dx.doi.org/10.21474/ijar01/13352.

Texto completo

Resumen

Heterocyclic compounds are numerous and diverse group of organic compounds. Heterocycles are abundantly found in nature and express various physiological properties. Heterocycles are intricately linked to all aspects of life. There are many heterocyclic compounds currently known, and the number is constantly rising owing to extensive synthetic development and their applications. Heterocyclic compounds are used significantly in a number of areas, including biochemistry and medicinal chemistry, and some others. They are predominantly synthesized in agrochemical and pharmaceutical industries due to their potential biological activities. This review article focuses on recently synthesized heterocyclic compounds and their different pesticidal activities such as antifungal, antibacterial, antiviral, nematocidal, insecticidal, acaricidal, and herbicidal.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Shaikh, Ansar R., Mazahar Farooqui, R. H. Satpute y Syed Abed. "Overview on Nitrogen containing compounds and their assessment based on ‘International Regulatory Standards’". Journal of Drug Delivery and Therapeutics 8, n.º 6-s (21 de diciembre de 2018): 424–28. http://dx.doi.org/10.22270/jddt.v8i6-s.2156.

Texto completo

Resumen

Heterocyclic compounds have a role in most fields of sciences such as medicinal chemistry, biochemistry also another area of sciences. More than 90% of new drugscontain heterocycles and the interface between chemistry and biology, at which so much new scientific insight, discovery and application is taking place is crossed by heterocyclic compounds. Compounds derived from heterocyclic rings in pharmacy, medicine, agriculture, plastic, polymer and other fields.Most active heterocycles that have shown considerable biological actions as antifungal, anti-inflammatory, antibacterial, anticonvulsant, antiallergic, herbicidal, anticancer activity. There is always a strong need for new and efficient processes in synthesizing of new Heterocycles.Alum have been used as a novel catalyst in the synthesis of Schiff’s bases. Synthesized Schiff’s bases are free from use of ICH class 1 and Class 2 solvents and also free from structural alerts genotoxic impurities. This review highlights on various aspects of heterocyclic compounds with its biological activity & regulatory assessment based on the ‘International Regulatory Standards’. Keywords: Heterocycles. Nitrogen containing compounds Biological activity, History, Regulatory assessment, International Regulatory Standards

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Maji, Pradip Kumar. "Recent Progress in the Synthesis of Pyrimidine Heterocycles: A Review". Current Organic Chemistry 24, n.º 10 (11 de agosto de 2020): 1055–96. http://dx.doi.org/10.2174/1385272824999200507123843.

Texto completo

Resumen

Pyrimidine heterocycles are proven to be biologically active heterocycles, found in many biological systems, displaying a broad spectrum of biological activities including anticancer, anxiolytic, antioxidant, antiviral, antifungal, anticonvulsant, antidepressant and antibacterial activities. Recently, various synthetic approaches, synthetic strategy, the variation of substrates and study devoted towards the evaluation of biological activities for the pyrimidine heterocycles have been reported in the literature. This review article describes the synthesis of various biologically interesting pyrimidine heterocyclic ring systems using various nitrogen building blocks.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Dudhe, Anshu R., Sachinkumar D. Gunjal, Sampath AG, Sushama Rawat y YY Nandurkar. "An Overview on Nitrogen-containing Heterocyclic Compounds as Anticancer Agents". INTERNATIONAL JOURNAL OF PHARMACEUTICAL QUALITY ASSURANCE 14, n.º 04 (25 de diciembre de 2023): 1296–301. http://dx.doi.org/10.25258/ijpqa.14.4.72.

Texto completo

Resumen

Cancer accounts for nearly 10 million losses each year. Among the most prevalent cancer types are breast, lung, colon, rectum, and prostate cancers. Astonishingly, around one-third of cancer-related deaths can be attributed to factors such as tobacco usage, a high body mass index (BMI), alcohol consumption, restricted ingestion of fruits and vegetables, and inadequate bodily bustle. In the field of pharmaceuticals, heteroatoms and heterocyclic compounds frequently assume crucial roles and serve as common structural components in numerous active natural products. Statistically, the majority of biologically active compounds is either heterocycles themselves or incorporate a heterocyclic element, with nitrogen-containing heterocycles being the most prevalent structural framework in these intricate molecules. These findings underscore the significant and ever-evolving role of heterocycles in contemporary drug blueprints and drug sighting practice. The chief hub of the review was to explore the documented anti-cancer properties of nitrogen-containing heterocyclic compounds, as reported in current scientific literature.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Niedballa, Jonas y Thomas J. J. Müller. "Heterocycles by Consecutive Multicomponent Syntheses via Catalytically Generated Alkynoyl Intermediates". Catalysts 12, n.º 1 (13 de enero de 2022): 90. http://dx.doi.org/10.3390/catal12010090.

Texto completo

Resumen

Multicomponent processes are beneficial tools for the synthesis of heterocycles. As densely substituted bifunctional electrophiles, ynones are essential intermediates by applying cyclocondensations or cycloadditions in numerous heterocycle syntheses. The respective alkynoyl intermediates are generally accessible by palladium-, copper- and palladium/copper-catalyzed alkynylation. In turn, the mild reaction conditions allow for a fast and versatile entry to functional heterocycles in the sense of consecutive multicomponent processes. This review collates and presents recent advances in accessing thirteen heterocycle classes and their applications by virtue of catalytic alkynoyl generation in diversity-oriented multicomponent syntheses in a one-pot fashion.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

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, n.º 4 (10 de septiembre de 2019): 61–72. http://dx.doi.org/10.32352/0367-3057.4.19.07.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Sparr, Christof y Christian Fischer. "Configurationally Stable Atropisomeric Acridinium Fluorophores". Synlett 29, n.º 16 (3 de agosto de 2018): 2176–80. http://dx.doi.org/10.1055/s-0037-1610233.

Texto completo

Resumen

Arylated heterocyclic fluorophores are particularly useful scaffolds for numerous applications, such as bioimaging or synthetic photochemistry. While variation of the substitution pattern at the heterocycle and aryl groups allows dye modulation, the bond rotational barriers are also strongly affected. Unsymmetrically substituted ring systems of rotationally restricted arylated heterocycles therefore lead to configurationally stable atropisomeric fluorophores. Herein, we describe these characteristics by determining the properties and configurational stability of atropisomeric, tri-ortho-substituted naphthyl-acridinium fluorophores. A significant barrier to rotation of >120 kJ mol–1 was measured, which renders these dyes and related compounds distinct atropisomers with stereoisomer-specific properties over a broad temperature range.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Birzan, Liviu, Mihaela Cristea, Constantin C. Draghici y Alexandru C. Razus. "Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines". Revista de Chimie 69, n.º 1 (15 de febrero de 2018): 64–69. http://dx.doi.org/10.37358/rc.18.1.6045.

Texto completo

Resumen

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Li, Jin-Heng, De-Lie An y Jing-Hao Qin. "Recent Advances in Cycloaddition Reactions with Alkynes to Construct Heterocycles". Synthesis 52, n.º 24 (13 de octubre de 2020): 3818–36. http://dx.doi.org/10.1055/s-0040-1707355.

Texto completo

Resumen

Heterocyclic compounds, especially N-heterocycles and O-heterocycles, are prominent structural motifs present in numerous natural products and medically and/or economically important compounds. This review aims to describe the development of transition-metal-catalyzed cycloaddition reactions of functionalized m-atom partners with alkynes to access a wide range of five-, six-, and seven-membered heterocycles, that is functionalized N-heterocycles and O-heterocycles such as azepines, isoquinolines, isocoumarins, spiroheterocycles, indoles, furans, and pyrroles, in a selectively controlled manner with an emphasis on scope and limitations and with a discussion of the mechanisms.1 Introduction2 Intermolecular Cycloaddition To Construct Azepine Derivatives2.1 [5+2] Cycloaddition2.2 [3+2+2] Cycloaddition2.3 [3+2]/[5+2] Cycloaddition3 Intermolecular [4+2] Cycloaddition To Construct Isoquinolines or Isocoumarins4 Intermolecular [3+2] Cycloaddition To Construct Spiroheterocyclic Compounds, Indoles, Furans, and Pyrroles5 Summary and Outlook

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Moulis, Pierre, Cécile Miot-Sertier, Laure Cordazzo, Olivier Claisse, Céline Franc, Laurent Riquier, Warren Albertin et al. "Which microorganisms contribute to mousy off-flavour in our wines?" OENO One 57, n.º 2 (16 de mayo de 2023): 177–87. http://dx.doi.org/10.20870/oeno-one.2023.57.2.7481.

Texto completo

Resumen

In recent years, the frequency of occurrence of mousy off-flavours in wines has increased. This could be caused by the significant decrease in sulphur dioxide addition during processing, the increase in pH or even the trend for spontaneous fermentation in wine. This off-flavour was associated with Brettanomyces bruxellensis or lactic acid bacteria metabolisms. Three N-heterocyclic compounds (APY, ETHP, ATHP) were described as involved in mousiness perception. Thus far, no study addressed the variability in that N-heterocycles production according to microorganism strains from different species. Twenty-five wines presenting mousy off-flavour were analysed. In total, 252 bacteria with 90.5 % of Oenococcus oeni and 101 yeast strains with 53.5 % of Saccharomyces cerevisiae were isolated and identified. Their capacity to produce mousy compounds was investigated using Stir Bar Sorptive Extraction-Gas Chromatography-Mass Spectrometry (SBSE-GC-MS) and a standardised N-heterocycle assay medium. While four and three species of yeast and bacteria, respectively, were isolated from mousy wines, only three species of microorganisms were associated with N-heterocycles production: B. bruxellensis, Lentilactobacillus hilgardii and Oenococcus oeni. The screening was then extended to collection strains for these three species to improve their genetic representativity. Our results show that the levels and the ratios of the three N-heterocycles present huge variations according to the species. In addition, it has been shown that in most mousy wines, B. bruxellensis was not found. Finally, an interesting correlation between ATHP and ETHP was identified.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Adak, Laksmikanta y Tubai Ghosh. "Recent Progress in Iron-Catalyzed Reactions Towards the Synthesis of Bioactive Five- and Six-Membered Heterocycles". Current Organic Chemistry 24, n.º 22 (18 de diciembre de 2020): 2634–64. http://dx.doi.org/10.2174/1385272824999200714102103.

Texto completo

Resumen

Heterocyclic compounds are the largely diverse organic molecules and find prevalent applications in the fine chemical industry, medicinal chemistry and agricultural science. They are also among the most commonly bearing frameworks in numerous drugs and pharmaceutical substances. Therefore, the development of convenient, efficient and environmentally benign methods to produce various types of heterocyclic compounds is an attractive area of research. For the synthesis and functionalization of heterocycles, enormous achievements have been attributed over the past decades. Recently, ironcatalyzed reactions have accomplished a noteworthy development in the synthesis of heterocycles. This review highlights some remarkable achievements in the iron-catalyzed synthesis of heterocyclic compounds published in the last five years.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Hoffman, Gavin R. y Allen M. Schoffstall. "Syntheses and Applications of 1,2,3-Triazole-Fused Pyrazines and Pyridazines". Molecules 27, n.º 15 (22 de julio de 2022): 4681. http://dx.doi.org/10.3390/molecules27154681.

Texto completo

Resumen

Pyrazines and pyridazines fused to 1,2,3-triazoles comprise a set of heterocycles obtained through a variety of synthetic routes. Two typical modes of constructing these heterocyclic ring systems are cyclizing a heterocyclic diamine with a nitrite or reacting hydrazine hydrate with dicarbonyl 1,2,3-triazoles. Several unique methods are known, particularly for the synthesis of 1,2,3-triazolo[1,5-a]pyrazines and their benzo-fused quinoxaline and quinoxalinone-containing analogs. Recent applications detail the use of these heterocycles in medicinal chemistry (c-Met inhibition or GABAA modulating activity) as fluorescent probes and as structural units of polymers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Kerru, Nagaraju, Lalitha Gummidi, Suresh Maddila, Kranthi Kumar Gangu y Sreekantha B. Jonnalagadda. "A Review on Recent Advances in Nitrogen-Containing Molecules and Their Biological Applications". Molecules 25, n.º 8 (20 de abril de 2020): 1909. http://dx.doi.org/10.3390/molecules25081909.

Texto completo

Resumen

The analogs of nitrogen-based heterocycles occupy an exclusive position as a valuable source of therapeutic agents in medicinal chemistry. More than 75% of drugs approved by the FDA and currently available in the market are nitrogen-containing heterocyclic moieties. In the forthcoming decade, a much greater share of new nitrogen-based pharmaceuticals is anticipated. Many new nitrogen-based heterocycles have been designed. The number of novel N-heterocyclic moieties with significant physiological properties and promising applications in medicinal chemistry is ever-growing. In this review, we consolidate the recent advances on novel nitrogen-containing heterocycles and their distinct biological activities, reported over the past one year (2019 to early 2020). This review highlights the trends in the use of nitrogen-based moieties in drug design and the development of different potent and competent candidates against various diseases.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Kumar, Adarsh, Ankit Kumar Singh, Harshwardhan Singh, Veena Vijayan, Deepak Kumar, Jashwanth Naik, Suresh Thareja et al. "Nitrogen Containing Heterocycles as Anticancer Agents: A Medicinal Chemistry Perspective". Pharmaceuticals 16, n.º 2 (14 de febrero de 2023): 299. http://dx.doi.org/10.3390/ph16020299.

Texto completo

Resumen

Cancer is one of the major healthcare challenges across the globe. Several anticancer drugs are available on the market but they either lack specificity or have poor safety, severe side effects, and suffer from resistance. So, there is a dire need to develop safer and target-specific anticancer drugs. More than 85% of all physiologically active pharmaceuticals are heterocycles or contain at least one heteroatom. Nitrogen heterocycles constituting the most common heterocyclic framework. In this study, we have compiled the FDA approved heterocyclic drugs with nitrogen atoms and their pharmacological properties. Moreover, we have reported nitrogen containing heterocycles, including pyrimidine, quinolone, carbazole, pyridine, imidazole, benzimidazole, triazole, β-lactam, indole, pyrazole, quinazoline, quinoxaline, isatin, pyrrolo-benzodiazepines, and pyrido[2,3-d]pyrimidines, which are used in the treatment of different types of cancer, concurrently covering the biochemical mechanisms of action and cellular targets.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Nayl, AbdElAziz A., Ashraf A. Aly, Wael A. A. Arafa, Ismail M. Ahmed, Ahmed I. Abd-Elhamid, Esmail M. El-Fakharany, Mohamed A. Abdelgawad, Hendawy N. Tawfeek y Stefan Bräse. "Azides in the Synthesis of Various Heterocycles". Molecules 27, n.º 12 (9 de junio de 2022): 3716. http://dx.doi.org/10.3390/molecules27123716.

Texto completo

Resumen

In this review, we focus on some interesting and recent examples of various applications of organic azides such as their intermolecular or intramolecular, under thermal, catalyzed, or noncatalyzed reaction conditions. The aforementioned reactions in the aim to prepare basic five-, six-, organometallic heterocyclic-membered systems and/or their fused analogs. This review article also provides a report on the developed methods describing the synthesis of various heterocycles from organic azides, especially those reported in recent papers (till 2020). At the outset, this review groups the synthetic methods of organic azides into different categories. Secondly, the review deals with the functionality of the azido group in chemical reactions. This is followed by a major section on the following: (1) the synthetic tools of various heterocycles from the corresponding organic azides by one-pot domino reaction; (2) the utility of the chosen catalysts in the chemoselectivity favoring C−H and C-N bonds; (3) one-pot procedures (i.e., Ugi four-component reaction); (4) nucleophilic addition, such as Aza-Michael addition; (5) cycloaddition reactions, such as [3+2] cycloaddition; (6) mixed addition/cyclization/oxygen; and (7) insertion reaction of C-H amination. The review also includes the synthetic procedures of fused heterocycles, such as quinazoline derivatives and organometal heterocycles (i.e., phosphorus-, boron- and aluminum-containing heterocycles). Due to many references that have dealt with the reactions of azides in heterocyclic synthesis (currently more than 32,000), we selected according to generality and timeliness. This is considered a recent review that focuses on selected interesting examples of various heterocycles from the mechanistic aspects of organic azides.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Xia, Xiao-Feng y Yan-Ning Niu. "Recent developments in the synthesis of nitrogen-containing heterocycles from β-aminovinyl esters/ketones as CC–N donors". Organic & Biomolecular Chemistry 20, n.º 2 (2022): 282–95. http://dx.doi.org/10.1039/d1ob01998h.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Kaur, Navjeet. "Metal and Non-Metal Catalysts in the Synthesis of Five-Membered S-Heterocycles". Current Organic Synthesis 16, n.º 2 (26 de marzo de 2019): 258–75. http://dx.doi.org/10.2174/1570179416666181207144430.

Texto completo

Resumen

Background:A wide variety of biological activities are exhibited by N, O and S containing heterocycles and recently, many reports appeared for the synthesis of these heterocycles. The synthesis of heterocycles with the help of metal and non-metal catalyst has become a highly rewarding and important method in organic synthesis. This review article concentrated on the synthesis of S-heterocylces in the presence of metal and non-metal catalyst. The synthesis of five-membered S-heterocycles is described here.Objective:There is a need for the development of rapid, efficient and versatile strategy for the synthesis of heterocyclic rings. Metal, non-metal and organocatalysis involving methods have gained prominence because traditional conditions have disadvantages such as long reaction times, harsh conditions and limited substrate scope.Conclusion:The metal-, non-metal-, and organocatalyst assisted organic synthesis is a highly dynamic research field. For ßthe chemoselective and efficient synthesis of heterocyclic molecules, this protocol has emerged as a powerful route. Various methodologies in the past few years have been pointed out to pursue more sustainable, efficient and environmentally benign procedures and products. Among these processes, the development of new protocols (catalysis), which avoided the use of toxic reagents, are the focus of intense research.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Munzeiwa, Wisdom A., Bernard Omondi y Vincent O. Nyamori. "Architecture and synthesis of P,N-heterocyclic phosphine ligands". Beilstein Journal of Organic Chemistry 16 (12 de marzo de 2020): 362–83. http://dx.doi.org/10.3762/bjoc.16.35.

Texto completo

Resumen

Diverse P,N-phosphine ligands reported to date have performed exceptionally well as auxiliary ligands in organometallic catalysis. Phosphines bearing 2-pyridyl moieties prominently feature in literature as compared to phosphines with five-membered N-heterocycles. This discussion seeks to paint a broad picture and consolidate different synthetic protocols and techniques for N-heterocyclic phosphine motifs. The introduction provides an account of P,N-phosphine ligands, and their structural and coordination benefits from combining heteroatoms with different basicity in one ligand. The body discusses the synthetic protocols which focus on P–C, P–N-bond formation, substrate and nucleophile types and different N-heterocycle construction strategies. Selected references are given in relation to the applications of the ligands.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Geisenberger, Josef, Jürgen Erbe, Jürgen Heidrich, Ulrich Nagela y Wolfgang Beck. "Pseudohalogenometallverbindungen, LXV [1] Synthese von Tetrazolen und Triazolen über die 1,3-dipolare Cycloaddition an die Azid-Liganden von polymeren Cobalt(III)-und Palladium(II)-Komplexen. Darstellung und Struktur von 5-TrichlormethyItetrazol / Pseudohalogeno Metal Compounds, LXV [1] Synthesis of Tetrazoles and Triazoles via 1,3-Dipolar Cycloaddition to the Azido Ligands of Polymerie Cobalt(III) and Palladium(II) Complexes. Synthesis and Structure of 5-Trichloromethyltetrazole". Zeitschrift für Naturforschung B 42, n.º 1 (1 de enero de 1987): 55–64. http://dx.doi.org/10.1515/znb-1987-0112.

Texto completo

Resumen

Abstract The cycloaddition of nitriles and of dimethylacetylenedicarboxylate to the azide ligand of polymeric Schiff Base cobalt(III) and phosphine palladium(II) complexes gives the corresponding tetrazolate and triazolate complexes from which the heterocycles could be cleaved by hydrogen chloride. Usually the yields are low; if the heterocycle is soluble in ether or sublimable, yields up to 30% have been obtained. Using this method the hitherto unknown 5-trichlormethyltetrazole could be prepared which was characterized by an X-ray structural analysis. Similarly, the cyclo-addition of azido(tetraphenylporphinato)cobalt(III) with nitriles, cyclohexylisocyanide and MeO2CC≡CCO2 Me affords the corresponding complexes with heterocyclic ligands. The prepa-ration of tetraphenylporphyrinato(tricyanmethanido)cobalt(III), (TPP)CoN=CC(CN)2 , is reported.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Maciejewski, Andrzej, Anna Jaworska-Augustyniak, Dariusz Radocki, Ronald G. Sutherland y Adam Piórko. "An efficient photochemical formation of phenoxazine and phenothiazine from their respective cyclopentadienyliron complexes". Collection of Czechoslovak Chemical Communications 54, n.º 8 (1989): 2171–75. http://dx.doi.org/10.1135/cccc19892171.

Texto completo

Resumen

The photochemical liberation of phenoxazine and phenothiazine from their cyclopentadienyliron complexes was studied in THF, methanol and dimethylsulfoxide. Quantum yields of decay of the complexes and the formation of free heterocycles have been determined to be about 1.0, independent of solvent, concentration and wavelength of light used. The ease of isolation of free heterocycles after photolysis show that this efficient way of heterocycle recovery is superior to the previously utilized pyrolytic sublimation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Perlmutter, Patrick. "The Nucleophilic Addition/Eiectrophilic Ring Closure Route to Bio-Active Heterocycles". Current Medicinal Chemistry 3, n.º 2 (abril de 1996): 139–52. http://dx.doi.org/10.2174/092986730302220302101738.

Texto completo

Resumen

Abstract: Many bio-active compounds contain one or more saturated or partially saturated heterocycles. Most of these contain one or more stereo centres. As a result any attempts to synthesize these compounds must take full account of the stereochemistry. In this article a new approach to the stereoselective synthesis of heterocycles is reviewed. The emphasis is on oxygen-containing heterocycles. The approach involves a sequence of a nucleophilic addition reaction followed by an electrophilic ring closure. Examples are given of the stereoselective synthesis of the heterocyclic subunits of macrolide and polyether antibiotics, ybutyrolactone autoregulators, marine polyether toxins and C-glycosides.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Zhu, Daqian, Zhouming Wu, Liyun Liang, Yameng Sun, Bingling Luo, Peng Huang y Shijun Wen. "Heterocyclic iodoniums as versatile synthons to approach diversified polycyclic heteroarenes". RSC Advances 9, n.º 57 (2019): 33170–79. http://dx.doi.org/10.1039/c9ra07288h.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Mohareb, Rafat y Hanaa Hana. "Synthesis of progesterone heterocyclic derivatives of potential antimicrobial activity". Acta Pharmaceutica 58, n.º 1 (1 de marzo de 2008): 29–42. http://dx.doi.org/10.2478/v10007-007-0043-3.

Texto completo

Resumen

Synthesis of progesterone heterocyclic derivatives of potential antimicrobial activityThe aim of this work was to synthesize steroidal heterocycles and to elucidate the potential role of these compounds as antimicrobial agents. The synthesis of steroidal heterocycles containing the pyrazole, isoxazole, thiazole, pyrane, pyridine, pyridazine, or benzopyrane ring attached to the pregnene nucleus is reported. Progesterone (1) reacts with dimethyl formamide dimethyl acetal to form enamine2. Heterocyclization of2with hydrazines, hydroxylamine, glycine, ethyl acetoacetate or cyanomethylene afforded novel steroidal heterocyclic derivatives. Thein vitroantimicrobial evaluation showed that all synthesized compounds show activity against the used strains of Gram positive bacteria and fungi.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Groso, Emilia y Corinna Schindler. "Recent Advances in the Application of Ring-Closing Metathesis for the Synthesis of Unsaturated Nitrogen Heterocycles". Synthesis 51, n.º 05 (8 de febrero de 2019): 1100–1114. http://dx.doi.org/10.1055/s-0037-1611651.

Texto completo

Resumen

This short review summarizes recent advances relating to the application of ring-closing olefin-olefin and carbonyl-olefin metathesis reactions towards the synthesis of unsaturated five- and six-membered nitrogen heterocycles. These developments include catalyst modifications and reaction designs that will enable access to more complex nitrogen heterocycles.1 Introduction2 Expansion of Ring-Closing Metathesis Methods3 Evaluation of Catalyst Design4 Indenylidene Catalysts5 Unsymmetrical N-Heterocyclic Carbene Ligands6 Carbonyl-Olefin Metathesis7 Conclusions

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Breitwieser, Kevin y Peter Chen. "Crystal structure of a 1,1-dibutyl-1H,3H-naphtho[1,8-cd][1,2,6]oxastannaborinin-3-ol". Acta Crystallographica Section E Crystallographic Communications 77, n.º 2 (26 de enero de 2021): 180–83. http://dx.doi.org/10.1107/s2056989021000712.

Texto completo

Resumen

The title oxastannaborininol compound, [Sn(C4H9)2(C10H7BO2)], has been synthesized and crystallized. While heterocycles containing a C–O–B group are common, heterocycles containing an E–O–B unit, where E is an element of the carbon group except for carbon, are rare. In fact, while heterocycles containing Si–O–B units are occasionally reported (although without crystal structures), there are no reports for the corresponding germanium, tin or lead analogues. Herein, the first synthesis and crystal structure of a heterocycle containing an Sn–O–B unit is described. The asymmetric unit contains one molecule showing a notable disorder of the tin atom and the butyl groups. They occupy two sets of positions with site-occupancy factors of 0.295 (6) and 0.705 (6).

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Huang, Pengfei, Pan Wang, Shengchun Wang, Shan Tang y Aiwen Lei. "Electrochemical oxidative [4 + 2] annulation of tertiary anilines and alkenes for the synthesis of tetrahydroquinolines". Green Chemistry 20, n.º 21 (2018): 4870–74. http://dx.doi.org/10.1039/c8gc02463d.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Boelke, Andreas, Soleicha Sadat, Enno Lork y Boris J. Nachtsheim. "Pseudocyclic bis-N-heterocycle-stabilized iodanes – synthesis, characterization and applications". Chemical Communications 57, n.º 60 (2021): 7434–37. http://dx.doi.org/10.1039/d1cc03097c.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Li, Xianwei, Tianzhang Wang, Yu-Jing Lu, Shaomin Ji, Yanping Huo y Bifu Liu. "Copper-catalyzed oxidative multicomponent reaction: synthesis of imidazo fused heterocycles with molecular oxygen". Organic & Biomolecular Chemistry 16, n.º 39 (2018): 7143–51. http://dx.doi.org/10.1039/c8ob01532e.

Texto completo

Resumen

An oxidative cascade that involves multicomponent reaction comprising a terminal alkyne, 2-amino N-heterocycle, benzyl or allylic bromide with molecular oxygen, delivering densely functionalized imidazo fused heterocycles, is achieved.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Abbas, Sumayah Saadi, Azhar Mahdi Jasim, Tayseer Hamid Shakir y Iman Saadi Abbas. "Anticancer Activities of Some Heterocyclic Compounds Containing an Oxygen Atom: A Review". Al-Rafidain Journal of Medical Sciences ( ISSN: 2789-3219 ) 4 (27 de abril de 2023): 60–67. http://dx.doi.org/10.54133/ajms.v4i.109.

Texto completo

Resumen

The purpose of this study is to underline the progression and development of research regarding oxygen-containing heterocycles as well as the contribution that some oxygen-containing heterocycles have made as anticancer medicines. A series of publications about the antitumor effects of derivatives of heterocyclic compounds containing an oxygen atom, such as furan, benzofuran, oxazole, benzoxazole, and oxadiazole, were evaluated, and their anticancer activities showed encouraging results when compared to those of established standard treatments.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Mir, Reyaz Hassan, Roohi Mohi-ud-din, Taha Umair Wani, Mohammad Ovais Dar, Abdul Jaleel Shah, Bashir Lone, Chawla Pooja y Mubashir Hussain Masoodi. "Indole: A Privileged Heterocyclic Moiety in the Management of Cancer". Current Organic Chemistry 25, n.º 6 (26 de marzo de 2021): 724–36. http://dx.doi.org/10.2174/1385272825666210208142108.

Texto completo

Resumen

Heterocyclic are a class of compounds that are intricately entwined into life processes. Almost more than 90% of marketed drugs carry heterocycles. Synthetic chemistry, in turn, allocates a cornucopia of heterocycles. Among the heterocycles, indole, a bicyclic structure consisting of a six-membered benzene ring fused to a five-membered pyrrole ring with numerous pharmacophores that generate a library of various lead molecules. Due to its profound pharmacological profile, indole got wider attention around the globe to explore it fully in the interest of mankind. The current review covers recent advancements on indole in the design of various anti-cancer agents acting by targeting various enzymes or receptors, including (HDACs), sirtuins, PIM kinases, DNA topoisomerases, and σ receptors.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Stephens, David E., Johant Lakey-Beitia, Jessica E. Burch, Hadi D. Arman y Oleg V. Larionov. "Mechanistic insights into the potassium tert-butoxide-mediated synthesis of N-heterobiaryls". Chemical Communications 52, n.º 64 (2016): 9945–48. http://dx.doi.org/10.1039/c6cc04816a.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Li, Wen, Jinyang Zhang, Min Wang, Ru Dong, Xin Zhou, Xin Zheng y Liping Sun. "Pyrimidine-fused Dinitrogenous Penta-heterocycles as a Privileged Scaffold for Anti-Cancer Drug Discovery". Current Topics in Medicinal Chemistry 22, n.º 4 (febrero de 2022): 284–304. http://dx.doi.org/10.2174/1568026622666220111143949.

Texto completo

Resumen

Abstract: Pyrimidine-fused derivatives that are the inextricable part of DNA and RNA play a key role in the normal life cycle of cells. Pyrimidine-fused dinitrogenous penta-heterocycles, including pyrazolopyrimidines and imidazopyrimidines are a special class of pyrimidine-fused compounds contributing to an important portion in anti-cancer drug discovery, which has been discovered as the core structure for promising anti-cancer agents used in the clinic or clinical evaluations. Pyrimidine-fused dinitrogenous penta-heterocycles have become one privileged scaffold for anti-cancer drug discovery. This review consists of the recent progress of pyrimidine-fused dinitrogenous penta-heterocycles as anti-cancer agents and their synthetic strategies. In addition, this review also summa-rizes some key structure-activity relationships (SARs) of pyrimidine-fused dinitrogenous penta-heterocycle derivatives as anti-cancer agents.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Kinjo, Rei y Bochao Su. "Construction of Boron-Containing Aromatic Heterocycles". Synthesis 49, n.º 14 (6 de junio de 2017): 2985–3034. http://dx.doi.org/10.1055/s-0036-1588832.

Texto completo

Resumen

Boron-containing aromatic systems exhibit unique electronic properties and reactivities that have been extensively studied for a long time. This review highlights the recent developments in the synthesis of aromatic boron-containing heterocycles. The organization of the contents is based on the sizes of rings and the heteroatoms other than boron. Early work in the field is briefly introduced, but the main focus is on recent reports published during the period of 2008 through 2016.1 Introduction2 Five-Membered Rings2.1 Borole Derivatives2.2 B,N-Heterocycles2.3 B,O-Heterocycles3 Six-Membered Rings3.1 Borabenzene Derivatives3.2 Boratabenzene Derivatives3.3 1,4-Diborabenzene3.4 B,N-Heterocycles3.5 B,E-Heterocycles (E = O, S, P, Te)4 Three-Membered Rings4.1 Borirenes4.2 Azadiboriridines4.3 Triboracyclopropenyl Dianion5 Four-Membered Rings5.1 bicyclo-Tetraborane(4)5.2 1,3-Diborete5.3 B,E-Heterocycles (E = N, P, As, Sb, Bi, O, S, Se)6 Seven-Membered Rings (Borepines)7 Conclusion and Perspective

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Zhang, Ming, Qiuhong Wang, Yiyuan Peng, Zhiyuan Chen, Changfeng Wan, Junmin Chen, Yongli Zhao, Rongli Zhang y Ai Qin Zhang. "Transition metal-catalyzed sp3 C–H activation and intramolecular C–N coupling to construct nitrogen heterocyclic scaffolds". Chemical Communications 55, n.º 87 (2019): 13048–65. http://dx.doi.org/10.1039/c9cc06609h.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

González-González, Carlos A., Juan Javier Mejía Vega, Ricardo García Monroy, Davir González-Calderón, David Corona-Becerril, Aydeé Fuentes-Benítes, Joaquín Tamariz Mascarúa y Carlos González-Romero. "A Novel and Chemoselective Process ofN-Alkylation of Aromatic Nitrogen Compounds Using Quaternary Ammonium Salts as Starting Material". Journal of Chemistry 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/4586463.

Texto completo

Resumen

The process ofN-alkylation of several pyrroles, indoles, and derivative heterocycles is herein described, using quaternary ammonium salts as the source of an alkylating agent. These reactions were carried out on several heterocyclic rings with triethylbenzylammonium chloride or tetradecyltrimethylammonium bromide and an NaOH solution at 50%, leading to a chemoselectiveN-alkylated product and an average yield of 73%. This is an alternative process to the traditional benzylation and methylation ofN-heterocycles with direct handling of alkyl halides.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Masdeu, Carme, Maria Fuertes, Endika Martin-Encinas, Asier Selas, Gloria Rubiales, Francisco Palacios y Concepcion Alonso. "Fused 1,5-Naphthyridines: Synthetic Tools and Applications". Molecules 25, n.º 15 (31 de julio de 2020): 3508. http://dx.doi.org/10.3390/molecules25153508.

Texto completo

Resumen

Heterocyclic nitrogen compounds, including fused 1,5-naphthyridines, have versatile applications in the fields of synthetic organic chemistry and play an important role in the field of medicinal chemistry, as many of them have a wide range of biological activities. In this review, a wide range of synthetic protocols for the construction of this scaffold are presented. For example, Friedländer, Skraup, Semmlere-Wolff, and hetero-Diels-Alder, among others, are well known classical synthetic protocols used for the construction of the main 1,5-naphthyridine scaffold. These syntheses are classified according to the nature of the cycle fused to the 1,5-naphthyridine ring: carbocycles, nitrogen heterocycles, oxygen heterocycles, and sulphur heterocycles. In addition, taking into account the aforementioned versatility of these heterocycles, their reactivity is presented as well as their use as a ligand for metal complexes formation. Finally, those fused 1,5-naphthyridines that present biological activity and optical applications, among others, are indicated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Ludwig, Miroslav, Iva Bednářová y Patrik Pařík. "Effect of Medium on Acid-Catalyzed Decomposition of N-(Phenylazo)-Substituted Nitrogen Heterocycles". Collection of Czechoslovak Chemical Communications 64, n.º 10 (1999): 1654–72. http://dx.doi.org/10.1135/cccc19991654.

Texto completo

Resumen

Four N-(phenylazo)-substituted saturated nitrogen heterocyclics were synthesized and their structure was confirmed by 1H and 13C NMR spectroscopy. The kinetics of their acid-catalyzed decomposition were studied at various concentrations of the catalyst (pivalic acid) in 40, 30, and 20% (v/v) aqueous ethanol at 25 °C. The values obtained for the observed rate constants were processed by the non-linear regression method according to the suggested kinetic models and by the method of principal component analysis (PCA). The interpretation of the results has shown that the acid-catalyzed decomposition of the heterocyclics under the conditions used proceeds by the mechanism of general acid catalysis, the proton being the dominant catalyst particle of the rate-limiting step. The decrease in the observed rate constant at higher concentrations of the catalyst was explained by the formation of a non-reactive complex composed of the undissociated acid and the respective N-(phenylazo)heterocycle. The effect of medium and steric effect of the heterocyclic moiety on the values of catalytic rate constant are discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Georghiou, Paris E. "Preface". Pure and Applied Chemistry 82, n.º 9 (1 de enero de 2010): iv. http://dx.doi.org/10.1351/pac20108209iv.

Texto completo

Resumen

The 22nd International Congress on Heterocyclic Chemistry (ICHC-22) was held 2-7 August 2009 in St. John's, Newfoundland and Labrador, Canada. St. John's, the capital of Canada's youngest Province, Newfoundland and Labrador, is also Canada’s oldest and North America’s most easterly city. The Conference was chaired by Prof. Mohsen Daneshtalab (School of Pharmacy, Memorial University of Newfoundland) and was organized by the School of Pharmacy and the Chemistry Department at Memorial University of Newfoundland.Approximately 260 participants from over 30 different countries attended. The scientific program consisted of 10 plenary lectures, 19 invited lectures, 52 short communications, and 115 posters. Prof. Samuel Danishefsky (Sloan-Kettering Institute for Cancer Research, Columbia University) was honored with the 2009 ISHC Senior Award in Heterocyclic Chemistry, and Prof. John Wood (Colorado State University) was the 2009 Katritzky Junior Award winner. A special symposium entitled "Focus on heterocycles in organic synthesis today and tomorrow" was held during the Congress as a tribute to Prof. Victor Snieckus (Queen's University, Kingston) for his research accomplishments and long-time contribution to the International Society of Heterocyclic Chemistry (ISHC).The five Congress themes were:- New Methods in Heterocyclic Chemistry- Biologically Active Heterocycles (Pharmaceuticals/Agrochemicals)- Heterocyclic Natural Products and their Analogues- Applications of Heterocycles in Organic Synthesis- Heterocycles in Materials ScienceBesides the collection of 9 papers that are based on the plenary and invited lectures included in this issue of Pure and Applied Chemistry, the ICHC-22 Book of Abstracts is available online and can be downloaded for free from http://www.ichc2009.ca/abstract_book.pdf in pdf format.ICHC-23 will be held in Glasgow, Scotland, 31 July to 5 August 2011 with the following five main themes of heterocyclic chemistry: synthetic methodology, natural products and complex molecule synthesis, materials, medicinal chemistry, and nanochemistry. The conference will be chaired by Prof. Colin Suckling (University of Strathclyde).The organizers are grateful to all who contributed to a successful scientific program, especially to the speakers and to our public and private sponsors: City of St. John's, Memorial University of Newfoundland, IUPAC, Thieme, Wiley-Blackwell, Elsevier, Taiho Pharmaceutical Co., ChemRoutres Corporation, and American Diagnostica, Inc.Paris E. GeorghiouConference Editor

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Wang, Min, Zi-Qiang Rong y Yu Zhao. "Stereoselective synthesis of ε-lactones or spiro-heterocycles through NHC-catalyzed annulation: divergent reactivity by catalyst control". Chem. Commun. 50, n.º 97 (2014): 15309–12. http://dx.doi.org/10.1039/c4cc07788a.

Texto completo

Resumen

NHC-catalyzed divergent annulation of enals with heterocyclic enones was developed to produce benzofuran/indole-containing ε-lactones or spiro-heterocycles in a highly diastereo- and enantioselective fashion.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Heterocycles"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros