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Topic: Heterocycles

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In the News (Tue 23 Oct 18)

  Heterocyclic Chemistry
Thus, the location of a fused ring may be indicated by a lowercase letter which designates the edge of the heterocyclic ring involved in the fusion, as shown by the pyridine ring in the green shaded box.
An important characteristic of aromaticity is enhanced thermodynamic stability, and this is usually demonstrated by relative heats of hydrogenation or heats of combustion measurements.
Indeed, once one understands the ortho-para and meta-directing character of these substituents, their directing influence on heterocyclic ring substitution is not difficult to predict.
www.cem.msu.edu /~reusch/VirtualText/heterocy.htm   (4072 words)

 Heterocycles - Elsevier
Since its launch in 1973, Heterocycles has provided a platform for the rapid exchange of research in the areas of organic, pharmaceutical, analytical, and medicinal chemistry of heterocyclic compounds.
Heterocycles is owned and published by The Japan Institute of Heterocyclic Chemistry (www.heterocycles.com).
The distribution of Heterocycles outside Japan is handled by Elsevier.
www.elsevier.com /wps/find/journaldescription.cws_home/424830/description   (249 words)

 Unbound MEDLINE | The recent impact of solid-phase synthesis on medicinally relevant benzoannelated nitrogen ...
Benzoannelated heterocycles such as benzodiazepines and indoles can be prepared efficiently through cyclization on solid supports, although no single approach is currently universal for the preparation of all benzoannelated N-heterocycle chemistries.
Classical heterocycle forming reactions such as the Fischer indole, the Bischler-Napieralski tetrahydroisoquinoline, the Pictet-Spengler tetrahydro-beta-carboline, the Tsuge, the Nenitzescu and the Richter cinnoline reaction are presented.
Cyclative cleavage from the solid support is particularly suitable for the synthesis of heterocycles while particular emphasis has been focused on the synthesis of libraries and the use of combinatorial chemistry techniques.
www.unboundmedicine.com /medline/ebm/record/12057632/abstract/The_recent_impact_of_solid_phase_synthesis_on_medicinally_relevant_benzoannelated_nitrogen_heterocycles   (190 words)

 RASalvatore.com Bookstore
Heterocycles are of paramount importance in the pharmaceutical industry and palladium chemistry is one of the most novel and efficient ways of making heterocycles.
A myriad of heterocycles are biologically active and therefore of paramount importance to medicinal and agricultural chemists.
The large body of data regarding palladium-mediated polymerization of heterocycles in material chemistry is not focused here; neither is coordination chemistry involving palladium and heterocycles.
www.rasalvatore.com /bookstore/itemDetails.aspx?asin=0080451160   (943 words)

 Mixture Sciences, Inc. - Heterocycles
Heterocyclic compounds offer a high degree of structural diversity and have proven to be broadly and economically useful as therapeutic agents.
Mixture Sciences' heterocyclic libraries have been successfully used in a wide range of bioassays by both pharmaceutical companies and academic institutions in order to identify novel enzyme inhibitors, receptor agonists and antagonists, antimicrobial, antifungal, and antiviral compounds.
The following is a representative list of Mixture Sciences' heterocyclic templates as well as the number of compounds contained in each of these libraries.
www.mixturesciences.com /Technology/Heterocycles.htm   (99 words)

 Preparation of 5-membered ring heterocycles - Patent 5453516
A process for preparing 5-membered ring heterocycles of the general formula I as claimed in claim 1, wherein the reaction is carried out at temperatures from 100.degree.
The present application relates to a process for preparing 5-membered ring heterocycles by reacting corresponding 5-membered ring heterocycles carrying hydrogen in the alpha position to the carbonyl group with dimethyl or ethylene carbonate in the presence of nitrogen-containing bases as catalysts at elevated pressures.
The 5-membered ring heterocycles (lactones and lactams, especially butyrolactones and pyrrolidones) of the general formula II can be reacted with dimethyl carbonate or ethylene carbonate in the presence of nitrogen-containing bases, e.g.
www.freepatentsonline.com /5453516.html   (1888 words)

 Addition of Lithiated Heterocycles to Nitrones
A variety of heterocyclic systems including oxazolines[3], benzotriazole[4], furan[5] and thiazole[6] can be used as synthetic equivalents of several functionalities such as formyl and carboxyl groups.
Several work has been devoted to the nucleophilic addition of metalated heterocycles to chiral aldehydes[7] and imines[8].
Application of this technology to the synthesis of various heterocyclic compounds now becomes of interest, and further synthetic applications of the obtained products are under investigation in our laboratory.
www.ch.ic.ac.uk /ectoc/echet98/pub/010/index.htm   (1346 words)

 Technical Summary : MMS Publication 2000-060 Biodegradation of Aromatic Heterocycles from Petroleum Produced Water, and ...   (Site not responding. Last check: )
Marine sediment is being collected and exposed to oxidized and reduced conditions in microcosms where each sample is exposed to mixtures of heterocycles.
Attempts are being made to enhance the biodegradation of heterocycles by selecting for effective microbial communities.
A series of heterocyclic chemicals found in produced waters and pyrogenic products is being examined for biodegradation under different physicochemical conditions in sediment-water microcosms maintained in the laboratory.
www.gomr.mms.gov /homepg/regulate/environ/techsumm/2000/2000-060.html   (771 words)

 Asymmetric Synthesis of Nitrogen Heterocycles
The asymmetric synthesis of nitrogen heterocycles is of continuing interest to medicinal and bio-organic chemistry.
Amino acids continue to be useful starting materials for the preparation of enantiomerically-pure heterocycles.
Henk Hiemstra of the University of Amsterdam and Floris Rutjes of the University of Nijmegen report (J.
www.organic-chemistry.org /Highlights/2004/29November.shtm   (190 words)

 NWO - New synthetic methodology for biologically relevant nitrogen heterocycles.
Nitrogen heterocycles of different ring sizes, with different substitution patterns and embedded in various molecular frameworks constitute extremely important structure classes in the search for bioactivity.
Despite the large availability of methods to construct nitrogen heterocycles, there is still a strong need to further explore synthetic methods to efficiently synthesize novel heterocyclic structures, either in racemic, but preferentially in enantiomerically pure form.
Given the importance of nitrogen heterocyclic structures in different classes of natural products with potent biological activity, this part of the project aims at further exploring the synthetic scope of alkoxyallenes in the formation of functionalized nitrogen heterocycles.
www.nwo.nl /projecten.nsf/pages/2300133368   (271 words)

 Herbicidal N-aryl-substituted nitrogen-containing heterocycles - Patent 5069711
The N-aryl-substituted nitrogen-containing heterocycles of the formula (If) are compounds according to the invention and can be obtained with the aid of processes (a) or (b) according to the invention.
The N-aryl-substituted nitrogen-containing heterocycles of the formula (Ie) are compounds according to the invention and can be obtained with the aid of process (e) according to the invention.
The N-aryl-substituted nitrogen-containing heterocycles of the formula (Ig), which are required as starting substances for carrying out process (e-.alpha.) according to the invention, are compounds according to the invention and can be obtained with the aid of processes (a), (b) or (c) according to the invention.
www.freepatentsonline.com /5069711.html   (5802 words)

The literature has been organized according to the number of heteroatoms in heterocycles; the fused heterocycles have been located according to the heterocycle that was built under MWI or as a reaction of the heterocycles.
Heterocycles having either fused benzene rings or other heterocycles have been located under a separate title if sufficient literature is available.
The major research interests are devoted to explore novel approaches for synthetic methodologies in organic chemistry and the synthesis of heterocyclic compounds.
www.arkat-usa.org /home.aspx?VIEW=MANUSCRIPT&MSID=1664   (2876 words)

 chapter1   (Site not responding. Last check: )
Heterocycles can be divided into two subgroups: nonaromatic and aromatic.
Pyridine has a structure similar to that of benzene, except that one CH unit is replaced by a nitrogen atom.
The important difference between five- and six-membered heterocycles, the heteroatom contributes two electrons to the aromatic 6 π systems, where in six-membered heterocycles, the heteroatom contributes only one electron to that system.
education.sangji.ac.kr /~yhpark/chapter13.html   (566 words)

 Recent Advances in the Preparation of Heterocycles on Solid Support: A Review of the Literature
Small heterocycles, in particular, are used as rigid, highly functionalized molecular scaffolds and are biologically very interesting.
Surprisingly, no other heterocyclic compounds with one or two heteroatoms have been reported including the formation of oxiranes, thiiranes, oxaziridines, diaziridines, and diazirines, respectively.
The approach toward the preparation of these compounds was based on the intramolecular nucleophilic aromatic substitution of fluorine from the derivatives of 2-fluoro-5-nitrobenzaldehyde with the OH function of immobilized phenols.
pubs.acs.org /cgi-bin/jtextd?jcchff/2/3/html/cc000002f.html   (7865 words)

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