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Heterocyclic chemistry

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https://www.readbyqxmd.com/read/28231521/therapeutic-journey-of-2-4-thiazolidinediones-as-a-versatile-scaffold-an-insight-into-structure-activity-relationship
#1
REVIEW
Mohd Javed Naim, Md Jahangir Alam, Shujauddin Ahmad, Farah Nawaz, Neelima Shrivastava, Meeta Sahu, Ozair Alam
Thiazolidinedione is an important heterocyclic ring system, a pharmacophore and a privileged scaffold in medicinal chemistry; is a derivative of thiazolidine ring which came into existence for its role as antihyperglycemic agent and a specific ligand of PPAR's (Peroxisome proliferator activated receptor). Exhaustive research has led to determination of its vast biological profile with wide range of therapeutic applications. This review covers recent pharmacological advancements of thiazolidinedione moiety along with structure activity relationship so as to provide better correlation among different structures and their receptor interactions...
February 20, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28228852/3d-printed-fluidics-with-embedded-analytic-functionality-for-automated-reaction-optimisation
#2
Andrew J Capel, Andrew Wright, Matthew J Harding, George W Weaver, Yuqi Li, Russell A Harris, Steve Edmondson, Ruth D Goodridge, Steven D R Christie
Additive manufacturing or '3D printing' is being developed as a novel manufacturing process for the production of bespoke micro- and milliscale fluidic devices. When coupled with online monitoring and optimisation software, this offers an advanced, customised method for performing automated chemical synthesis. This paper reports the use of two additive manufacturing processes, stereolithography and selective laser melting, to create multifunctional fluidic devices with embedded reaction monitoring capability...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28222606/flexible-porphyrinoids
#3
Bartosz Szyszko, Michał J Białek, Ewa Pacholska-Dudziak, Lechosław Latos-Grażyński
This review underscores the conformational flexibility of porphyrinoids, a unique class of functional molecules, starting from the smallest triphyrins(1.1.1) via [18]porphyrins(1.1.1.1) and concluding with a variety of expanded porphyrinoids and heteroporphyrinoids, including the enormous [96]tetracosaphyrin(1.0.1.0.1.0.1.0.1.0.1.0.1.0.1.0.1.0.1.0.1.0.1.0). The specific flexibility of porphyrinoids has been documented as instrumental in the designing or redesigning of macrocyclic frames, particularly in the search for adjustable platforms for coordination or organometallic chemistry, anion binding, or mechanistic switches in molecular devices...
February 22, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28220966/nhc-based-tri-organyl-zn-alkyl-cations-synthesis-structure-isomerization-for-improved-stability-and-use-in-co2-functionalization
#4
Samuel Dagorne
Tri-organyl and tri-coordinate N-heterocyclic carbene Zn-NHC alkyl cations (nNHC)2Zn-Me+ (nNHC = C2-bonded-IMes/-IDipp; 3+ and 4+) were first synthesized and structurally characterized via ionization of the corresponding neutral precursors (NHC)ZnMe2 with [Ph3C][B(C6F5)4] in the presence of 1 equiv. of free NHC. Cations 3+-5+ are the first Zn cations of the type Zn(C)(C')(C'')+ (C, C', C'' = σ-donor carbyl ligand). While cation (nIMes)2Zn-Me+ (3+) is stable, its sterically congested analogue (nIDipp)2Zn-Me+ (4+) readily undergoes a nNHC-to-aNHC isomerization in the presence of THF or IDipp to afford the more thermodynamically stable (aDipp)(nIDipp)Zn-Me+ (aIDipp = C5-bonded IDipp, 5+), reflecting the adaptable-to-sterics coordination chemistry of these cations for improved stability...
February 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28218492/nhc-catalyzed-metathesis-and-phosphorylation-reactions-of-disulfides-development-and-mechanistic-insights
#5
Reece Douglas Crocker, Mohanad A Hussein, Junming Ho, Thanh Vinh Nguyen
The development of efficient methods for the metathesis and phosphorylation reactions of disulfide compounds is of widespread interests due to their important synthetic utility in polymer, biological, medicinal and agricultural chemistry. Herein, we demonstrate the use of N-heterocyclic carbenes (NHCs) as versatile organocatalysts to promote these challenging reactions under mild conditions. This metal-free oxidant-free protocol is operationally simple with very short reaction times. The interplay between the nucleophilicity and basicity of NHCs in these reactions were also elucidated by NMR studies and high-level ab initio calculations...
February 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28215139/bridgehead-nitrogen-thiazolo-3-2-a-pyrimidine-a-privileged-structural-framework-in-drug-discovery
#6
Amit K Keshari, Ashok K Singh, Sudipta Saha
Thiazolopyrimidine derivatives containing bridgehead nitrogen atom are now-a-days attracting the attention of many medicinal chemists throughout the world to explore this framework for its potential. This biologically important scaffold is formed by the fusion of two aromatic rings, thiazole and pyrimidine, in such a way that one carbon atom at the ring junction is replaced by a nitrogen atom and is, therefore, being common for both the heterocyclic rings. One of the most common example of this type of fusion is thiazolo[3,2-a]pyrimidine which is being used perpetually with tremendous success in various field of therapeutic applications...
February 16, 2017: Mini Reviews in Medicinal Chemistry
https://www.readbyqxmd.com/read/28203667/quantifying-and-understanding-the-steric-properties-of-n-heterocyclic-carbenes
#7
Adrián Gómez-Suárez, David J Nelson, Steven P Nolan
This Feature Article presents and discusses the use of different methods to quantify and explore the steric impact of N-heterocyclic carbene (NHC) ligands. These include (a) the percent buried volume (%Vbur), which provides a convenient single number to measure steric impact and (b) steric maps, which provide a graphical representation of the steric profile of a ligand using colour-coded contour maps. A critical discussion of the scope and limitations of these tools is presented, along with some examples of their use in organometallic chemistry and catalysis...
February 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28198438/heterogeneous-nucleation-of-trichloroethylene-ozonation-products-in-the-formation-of-new-fine-particles
#8
Ning Wang, Xiaomin Sun, Jianmin Chen, Xiang Li
Free radicals in atmosphere have played an important role in the atmospheric chemistry. The chloro-Criegee free radicals are produced easily in the decomposition of primary ozonide (POZ) of the trichloroethylene, and can react with O2, NO, NO2, SO2 and H2O subsequently. Then the inorganic salts, polar organic nitrogen and organic sulfur compounds, oxygen-containing heterocyclic intermediates and polyhydroxy compounds can be obtained. The heterogeneous nucleation of oxidation intermediates in the formation of fine particles is investigated using molecular dynamics simulation...
February 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28176260/green-synthesis-spectrofluorometric-characterization-and-antibacterial-activity-of-heterocyclic-compound-from-chalcone-on-the-basis-of-in-vitro-and-quantum-chemistry-calculation
#9
Salman A Khan
2-amino-4-(4-bromophenyl)-8-methoxy-5,6-dihydrobenzo[h]quinoline-3-carbonitrile (ABDC) was synthesized by the reaction of (2E)-2-(4 bromobenzylidene) - 6 -methoxy-3,4-dihydronaphthalen-1(2H)-one (Chalcone) with malononitrile and ammonium acetate under microwave irradiation. Chalcone was synthesised by the reaction 4-bromobenzaldehyd, 6-methoxy-1,2,3,4-tetrahydro-naphthalin-1-one under the same condition. Structure of ABDC was conformed by (1)H and (13)C NMR, FT-IR, EI-MS spectral studies and elemental analysis...
February 8, 2017: Journal of Fluorescence
https://www.readbyqxmd.com/read/28171830/a-review-on-antioxidant-potential-of-bioactive-heterocycle-benzofuran-natural-and-synthetic-derivatives
#10
REVIEW
Karam Chand, Rajeshwari, Asha Hiremathad, Mahak Singh, M Amelia Santos, Rangappa S Keri
The majority of heterocycle compounds and typically common heterocycle fragments present in most pharmaceuticals currently marketed, alongside with their intrinsic versatility and unique physicochemical properties, have poised them as true cornerstones of medicinal chemistry. In this context, oxygen heterocycles exhibit diverse biological and pharmacological activities due in part to the similarities with many natural and synthetic molecules with known biological activity. Among oxygen containing heterocycles, benzofuran (synthetic and natural isolated) and its derivatives have attracted medicinal chemists and pharmacologists due to their pronounced biological activities and their potential applications as pharmacological agents such as antioxidant, antitumor, antiplatelet, antimalarial, antiinflammatory, antidepressant and anticonvulsant properties...
November 18, 2016: Pharmacological Reports: PR
https://www.readbyqxmd.com/read/28169325/aza-heterocyclic-receptors-for-direct-electron-transfer-hemoglobin-biosensor
#11
Vinay Kumar, D M Nikhila Kashyap, Suraj Hebbar, R Swetha, Sujay Prasad, T Kamala, S S Srikanta, P R Krishnaswamy, Navakanta Bhat
Direct Electron Transfer biosensors, facilitating direct communication between the biomolecule of interest and electrode surface, are preferable compared to enzymatic and mediator based sensors. Although hemoglobin (Hb) contains four redox active iron centres, direct detection is not possible due to inaccessibility of iron centres and formation of dimers, blocking electron transfer. Through the coordination of iron with aza-heterocyclic receptors - pyridine and imidazole - we report a cost effective, highly sensitive and simple electrochemical Hb sensor using cyclic voltammetry and chronoamperometry...
February 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28164423/catalytic-dearomatization-of-n-heteroarenes-with-silicon-and-boron-compounds
#12
Sukbok Chang, Sehoon Park
Dearomatized N-heterocycles provide a class of structural motifs important in the fields of synthetic organic chemistry and chemical biology. The catalytic dearomative reduction of unactivated N-heteroarenes using silicon and/or boron-containing compounds as a reductant is one of the most straightforward alternatives to hydrogenation. However, scattered precedents on the catalytic reduction of N-heteroaromatics with silane or borane reducing agents have been reported thus far, and a handful of elegant catalytic procedures for the reduction of N-aromatics have emerged only recently as a viable tool in organic synthesis...
February 5, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28160211/natural-product-molecular-fossils
#13
Heinz Falk, Klaus Wolkenstein
The natural products synthesized by organisms that were living a long time ago gave rise to their molecular fossils. These can consist of either the original unchanged compounds or they may undergo peripheral transformations in which their skeletons remain intact. In cases when molecular fossils can be traced to their organismic source, they are termed "geological biomarkers".This contribution describes apolar and polar molecular fossils and, in particular biomarkers, along the lines usually followed in organic chemistry textbooks, and points to their bioprecursors when available...
2017: Progress in the Chemistry of Organic Natural Products
https://www.readbyqxmd.com/read/28133650/silver-catalyzed-formal-3-2-cycloaddition-of-%C3%AE-trifluoromethylated-methyl-isocyanides-a-facile-stereoselective-synthesis-of-cf3-substituted-heterocycles
#14
Xue Zhang, Xin Wang, Yuelei Gao, Xianxiu Xu
An Ag-catalyzed formal [3+2]-cycloaddition of α-trifluoromethylated methyl isocyanides with polar double bonds has been developed for the facile access to trifluoromethylated oxazolines, imidazolines and pyrrolines under mild conditions. The practicality of this chemistry is demonstrated by the gram-scale synthesis of oxazolines with excellent yields and facile transformations of the formed oxazolines to trifluoromethylated β-amino alcohols in quantitative yields.
January 30, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28128923/base-mediated-hydroamination-of-alkynes
#15
Monika Patel, Rakesh K Saunthwal, Akhilesh K Verma
Inter- or intramolecular hydroamination reactions are a paradigmatic example of modern sustainable organic chemistry, as they are a catalytic, 100% atom-economical, and waste-free process of fundamental simplicity in which an amine is added to an alkyne substrate. Many enamines are found in many natural and synthetic compounds possessing interesting physiological and biological activities. The development of synthetic protocols for such molecules and their transformation is a persistent research topic in pharmaceutical and organic chemistry...
January 27, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28128514/structural-basis-of-the-interaction-of-cyclin-dependent-kinase%C3%A2-2-with-roscovitine-and-its-analogues-having-bioisosteric-central-heterocycles
#16
Michaela Nekardová, Ladislava Vymětalová, Prashant Khirsariya, Silvia Kováčová, Michaela Hylsová, Radek Jorda, Vladimír Kryštof, Jindřich Fanfrlík, Pavel Hobza, Kamil Paruch
The structural basis for the interaction of roscovitine and analogues containing 13 different bioisosteric central heterocycles with the enzyme cyclin-dependent kinase 2 (CDK2) is elucidated. Although all the central scaffolds are very similar to the purine core of roscovitine, the experimentally determined IC50 values of the inhibitors span three orders of magnitude. By using an extensive computational chemistry approach, the affinities of the inhibitors to CDK2 are determined as calculated binding scores of complexes of the inhibitors with the protein...
January 27, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28126288/medicinal-attributes-of-1-2-3-triazoles-current-developments
#17
REVIEW
Divya Dheer, Virender Singh, Ravi Shankar
1,2,3-Triazoles are important five-membered heterocyclic scaffold due to their extensive biological activities. This framework can be readily obtained in good to excellent yields on the multigram scale through click chemistry via reaction of aryl/alkyl halides, alkynes and NaN3 under ambient conditions. It has been an emerging area of interest for many researchers throughout the globe owing to its immense pharmacological scope. The present work aims to summarize the current approaches adopted for the synthesis of the 1,2,3-triazole and medicinal significance of these architectures as a lead structure for the discovery of drug molecules such as COX-1/COX-2 inhibitors (celecoxib, pyrazofurin), HIV protease inhibitors, CB1 cannabinoid receptor antagonist and much more which are in the pipeline of clinical trials...
January 18, 2017: Bioorganic Chemistry
https://www.readbyqxmd.com/read/28120894/regioselectivity-and-mechanism-of-synthesizing-n-substituted-2-pyridones-and-2-substituted-pyridines-via-metal-free-c-o-and-c-n-bond-cleaving-of-oxazoline-3-2-a-pyridiniums
#18
Bo Li, Susu Xue, Yang Yang, Jia Feng, Peng Liu, Yong Zhang, Jianming Zhu, Zhijian Xu, Adrian Hall, Bo Zhao, Jiye Shi, Weiliang Zhu
Novel intermediate oxazoline[3,2-a]pyridiniums were facilely prepared from 2-(2,2-dimethoxyethoxy)-pyridines via acid promoted intramolecular cyclization. Sequentially, the quaternary ammonium salts were treated with different nucleophiles for performing regioselective metal-free C-O and C-N bond-cleaving to afford prevalent heterocyclic structures of N-substituted pyridones and 2-substituted pyridines. The reaction mechanism and regioselectivity were then systematically explored by quantum chemistry calculations at B3LYP/6-31 g(d) level...
January 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28120464/the-3-nitro-2-pyridinesulfenyl-group-synthesis-and-applications-to-peptide-chemistry
#19
Cédric Rentier, Kentarou Fukumoto, Akihiro Taguchi, Yoshio Hayashi
The 3-nitro-2-pyridinesulfenyl chloride, commonly abbreviated as Npys-Cl, was among the first stable heterocyclic sulfenyl halides to be isolated. After its discovery, the Npys group was widely used as a protecting group for the amines, alcohols and thiols. Herein, we have reviewed some of the aspects of the Npys-Cl moiety, and its most promising recent uses are summarized, from the stability of the Npys protection of amines, hydroxyls and thiols and removal conditions for potential applications in peptide synthesis, to one of its most successful applications for the formation of mixed disulfides...
January 25, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28117015/editorial-thematic-issue-heterocycle-and-hydrocarbon-compounds-from-natural-sources-in-medicinal-chemistry-from-synthesis-to-computational-design-in-pharmacological-applications-part-ii
#20
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