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Topic: Heterocyclic ring

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	Heterocyclic compound - Wikipedia, the free encyclopedia
		Heterocyclic compounds are organic compounds which contain a ring structure containing atoms in addition to carbon, such as sulfur, oxygen or nitrogen, as part of the ring.
		They may be either simple aromatic rings or non-aromatic rings.
		Note that compounds such as cyclopropane, an anaesthetic with explosive properties, and cyclohexane, a solvent, are not heterocyclic, they are merely cycloalkanes.
	en.wikipedia.org /wiki/Heterocyclic_ring (103 words)

	Flavonoids
		In a few cases, the six-membered heterocyclic ring C occurs in an isomeric open form or is replaced by a five - membered ring.
		Various subgroups of flavonoids are classified according to the substitution patterns of ring C. Both the oxidation state of the heterocyclic ring and the position of ring B are important in the classification.
		It has been established that acetate gives rise to ring A and that phenylalamine, cinnamate and cinnamate derivatives are incorporated into ring B and C-2, -3, and -4 of the heterocyclic ring.
	www.friedli.com /herbs/phytochem/flavonoids.html (748 words)

	C:\PROGRAM FILES\SOFTQUAD\HOTMETAL PRO\gifs\contents.htm (Site not responding. Last check: 2007-10-29)
		Heterocyclic compounds are those which have a cyclic structure with two, or more, different kinds of atom in the ring.
		Since the ring can be of any size, from three- membered upwards, and since the heteroatoms can be drawn in almost any combination from a large number of the elements (though nitrogen, oxygen and sulfur are the most common), the number of possible heterocyclic systems is almost limitless.
		Heterocyclic compounds are very widely distributed in Nature and are essential to life; they play a vital role in the metabolism of all living cells.
	www.elsevier.com /homepage/saa/chc/foreword.htm (678 words)

	CHC indexes (Site not responding. Last check: 2007-10-29)
		The index mainly covers general classes of heterocyclic compound and specific heterocyclic compounds, but also included are natural products, other organic and organometallic compounds where their synthesis or use involves heterocyclic compounds, types of reaction, named reactions, spectroscopic techniques and topics involving heterocyclic compounds.
		Heterocycles have been included when they occur as a starting material or as a product, but not when they are reported as a non-isolable intermediate or as a solvent.
		Heterocyclic systems can be named by various methods, depending on ring size, the presence or absence of metal atoms, the availability of trivial names, etc.
	www.elsevier.com /homepage/saa/chc/indexs.htm (576 words)

	Amines & amides
		Heterocyclic aromatic amines - Heterocyclic aromatic amines are the abundant amines found in biological molecules.
		The term heterocyclic means that one or more nitrogen atoms are present in a ring structure with several carbon atoms.
		The fused-ring aromatic heterocycles that contain both a benzene ring and a heterocyclic aromatic ring occur widely in biological molecules.
	www.clas.ufl.edu /users/tmullins/BCH3023/lecturenotes10.html (822 words)

	Compounds having a plurality of nitrogenous substitutents - US Patent 6329523 (Site not responding. Last check: 2007-10-29)
		Heterocyclic ring systems may be saturated, partially saturated, or unsaturated and will contain at least one hetero atom such as N, O, or S. Illustrative non-heterocyclic ring systems useful in compounds of the invention include, but are not limited to, benzene, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, transcyclooctane, cyclooctyne, cyclohepta-1,3-diene, [10]annulene (cyclodecapentaene), and [9]annulene {cyclonona-1,3,5,7-tetraene}.
		Illustrative multiple ring heterocyclic systems include, but are not limited to, carbazole, acridine, xanthene, purine, 1,4-benzisoxazine, 1,2-benzisoxazine, 30 3,1,4-benzoxazine, 2,3,1-benzoxazine, 1,4,2-benzoxazine, 1,3,2-benzoxazine, pyrido[4,3-b]pyridine, pyrido[3,2-b]pyridine, pyrido[3,4-b]pyridine, naphthyridine, quinazoline, cinnoline, isoquinoline, quinoline, 1,2-benzoyran, anthranil, benzoxazole, indoxazine, indolazine, pyrano[3,4-b]pyrrole, 1,5-pyridine, 2-isobenzole, indolenine, indole, isothionaphthene, thionaphthene, isobenzofuran, benzofuran, and 2,2'-bipyridine.
		Heterocycles, including nitrogen heterocycles, suitable for use as functional groups include, but are not limited to, imidazole, pyrrole, pyrazole, indole, 1H-indazole, α-carboline, carbazole, phenothiazine, phenoxazine, tetrazole, triazole, pyrrolidine, piperidine, piperazine and morpholine groups.
	www.patentstorm.us /patents/6329523.html (16213 words)

	W0053.html (Site not responding. Last check: 2007-10-29)
		Several examples of 1,3,5-triazacyclohexanes bearing aryl substituents on the nitrogen atoms of the heterocyclic ring have appeared in the crystallographic literature, and their conformations, particularly the orientations of the aryl groups, have been described in detail.
		The aryl rings of N-substituted triazacyclohexanes have been found to assume equatorial-diaxial orientations in the solid state that minimize interactions between lone pairs of electrons, but in the C-substituted compounds I-IV the solid-state orientation of the aryl rings is triequatorial in each case.
		The heterocyclic ring assumes a chair conformation in which the orientations of the N-H bonds are axial, placing the lone pairs of electrons in equatorial positions in all four structures.
	www.hwi.buffalo.edu /ACA/ACA03/abstracts/text/W0053.html (239 words)

	Botany online: Ions and Small Molecules - Aromatic Hydrocarbons
		Ring systems with double bonds that cannot be localized are called mesomere systems.
		Heterocyclic rings are components of nucleotides that have an important role in the cell.
		Heterocyclic rings form together or with other molecular groups components that cover essential functions in the cell.
	www.biologie.uni-hamburg.de /b-online/e16/16i.htm (400 words)

	2-Substituted benzisothiazolones - United States Patent 4,243,669
		A class of 2-substituted benzisothiazolones carrying a nitrogen-containing heterocyclic ring are effective in inhibiting platelet aggregation and are therefore of value in the prophylactic and therapeutic treatment of thrombotic diseases.
		When either group R or R.sup.3 is a nitrogen-containing heterocyclic ring, such a ring may be aromatic or non-aromatic, and the attachment to the group X (in the case of group R) or the group NH (in the case of group R.sup.3) may be via, for example, the nitrogen atom or a carbon atom.
		R represents a nitrogen-containing heterocyclic ring, or a group of formula --NH.R.sup.3 wherein R.sup.3 is a nitrogen-containing heterocyclic ring the groups R and R.sup.3 being optionally substituted with a lower alkyl, carboxy or alkoxycarbonyl group; to whole blood or platelet-rich concentrates.
	xrint.com /patents/us/4243669 (3587 words)

	CHI C - Online Information article about CHI C
		general purposes, however, the symbol (2), in which the lateral rings are benzenoid and the medial ring fatty, represents quite adequately the syntheses, decompositions, and behaviour of anthracene.
		Thus furfurane yields the following rings by the introduction of one and two nitrogen atoms: - Thiophene yields a similar series: isothiazole (only known as the condensed ring, isobenzothiazole), thiazole, diazosulphides, piazthioles, azosulphimes and thiobiazole (the formulae are 'easily derived from the preceding series by replacing oxygen by sulphur).
		The pyridine ring condenses with the benzene ring to form quinoline and isoquinoline; acridine and phenanthridine are dibenzo-pyridines; naphthalene gives rise to a-and 0-naphthoquinolines and the anthrapyridines; anthracene gives anthraquinoline; while two pyridine nuclei connected by an inter-mediate benzene nucleus give the phenanthrolines.
	encyclopedia.jrank.org /CHA_CHR/CHI_C.html (5934 words)

	Imperial Chemical Industries Plc. [1990] 3 AIPO (13 March 1990) (Site not responding. Last check: 2007-10-29)
		Similarly the terms "acyl", "heteroatoms", "heterocyclic rings" and "heterocyclyl" are broad and indeterminate in scope.
		Although the term "heterocyclic ring" encompasses a large class of compounds I have no difficulty in understanding the meaning or scope of that term.
		Again although a large class of compounds is encompassed by the term "heterocyclic ring" it is not a significantly larger class than for example "aryl" or "alkyl" which are terms used in claim 2 of the specification (71196/87).
	www2.austlii.edu.au /~simon/aipo/1990_3.html (3916 words)

	Photothermographic material and image formation method utilizing the same - Patent 6749999
		Z.sup.1 represents a group required to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, an aromatic ring may condense to the nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring and a condensed ring thereof may have a substituent.
		The unsaturated heterocyclic group represented by B is preferably a 5- or 6-membered heterocyclic group constituted by atoms selected from carbon, oxygen, nitrogen and sulfur atoms.
		In the aforementioned formula (6), Z.sup.61 is a group required to complete a 5- or 6-membered nitrogen-containing heterocyclic ring, an aromatic ring may condense to the nitrogen-containing heterocyclic ring, and the nitrogen-containing heterocyclic ring and a condensed ring thereof may have a substituent.
	www.freepatentsonline.com /6749999.html (15522 words)

	Synthesis of Novel Heterocyclic Systems from a-(2-R-5-halogenopyrimidin-4-yl)-2-azahetarylacetonitriles. New Potential ...
		As part of our studies on new planar condensed heterocyclic compounds as new potential antitumor agents, we synthesized a series of compounds containing new heterocyclic ring systems pyrimido[4',5':4,5]pyrrolo[2,1-b]benzimidazole (22) and pyrimido[4',5':4,5]pyrrolo[2,1-b]benzthiazole (23), which are delivered from substituted hetarylacetonitriles 5-14 by the reaction of intramolecular nucleophilic cyclization.
		We were interested in studies of nucleophilic aromatic intramolecular substitution of the halogen atoms at the C-5 position by the nitrogen atom of hetaryl ring systems and synthesis of new condensed pyrimidines with a bridgehead nitrogen atom and their biological activity.
		Nucleophilic substitution at C-4 in the pyrimidine ring of 1, a-f yielded novel 2-substituted 5-halogeno pyrimidines 5-19, a-f.
	www.ch.ic.ac.uk /ectoc/echet98/pub/090 (676 words)

	Patent 6,589,759
		"Heterocyclic ring or group" refers to a saturated, unsaturated, cyclic or aromatic or polycyclic hydrocarbon group having about 3 to about 12 carbon atoms (preferably about 4 to about 6 carbon atoms) where 1 to about 4 carbon atoms are replaced by one or more nitrogen, oxygen and/or sulfur atoms.
		Heterocyclic groups can be unsubstituted or substituted with one, two or three substituents independently selected from alkyl, alkoxy, amino, alkylamino, dialkylamino, arylamino, diarylamino, alkylarylamino, hydroxy, oxo, thial, halo, carboxyl, carboxylic ester, alkylcarboxylic acid, alkylcarboxylic ester, aryl, arylcarboxylic acid, arylcarboxylic ester, amidyl, ester, carboxamido, alkylcarboxamido, arylcarboxamido, sulfonic acid, sulfonic ester, sulfonamido and nitro.
		"Arylheterocyclic ring" refers to a bi- or tricyclic ring comprised of an aryl ring, as defined herein, appended via two adjacent carbon atoms of the aryl ring to a heterocyclic ring, as defined herein.
	www.pharmcast.com /Patents/Yr2003/July2003/070803/6589759_Platelets070803.htm (6536 words)

	Heterocyclic compounds
		At least one heterocyclic ring component is found in about 50% of known organic compounds.
		The most common heterocyclic systems contain heteroatoms N, O or S and good examples of these are six-membered heterocycle pyridine and five-membered heterocycles pyrrole, furan and thiophene [52].
		−Heterocycles were involved at the very beginning of life in the genesis of DNA and play an essential role in many living systems.
	herkules.oulu.fi /isbn9514259971/html/x258.html (479 words)

	Method for forming a direct positive image - Patent 4968596
		A method for forming a direct positive image as claimed in claim 1, wherein the 4- to 12-membered nonaromatic heterocyclic ring represented by Q is a ring containing at least one atom selected from the group consisting of nitrogen, oxygen, sulfur and selenium atoms.
		A method for forming a direct positive image as claimed in claim 1, wherein the 4- to 12-membered nonaromatic heterocyclic ring represented by Q is a ring selected from the group consisting of cyclopentane, cyclohexane, cyclohexene, cycloheptane, indane, tetralin, tetrahydrofuran, tetrahydropyran, butyrolactone, pyrrolidone, tetrahydrothiophene, pyrrolidine, piperidine, pyridone, piperazine, perhydrothiazine, tetrahydroquinoline, and indoline rings.
		A nonaromatic heterocyclic ring completed by Q is one which contains at least one of nitrogen, oxygen, sulfur, or selenium or/and so on as hetero atom(s).
	www.freepatentsonline.com /4968596.html (11398 words)

	[No title]
		Heterocyclic aromatic amines are the most abundant amines found in biological molecules.
		One or more nitrogen atoms are present in a ring structure with carbon atoms.
		Pyrrole is aromatic like benzene, and even though it has a five-membered ring it has six pi electrons in a cyclic conjugated pi-orbital system.
	www.clas.ufl.edu /users/tmullins/BCH3023/fall98/lecturenotes10.html (763 words)

	single stranded polymers 4 (rule 1)
		of the two rings or ring systems of the same size containing the same number and kind of heteroatoms, the senior system is that one with the lower locants for the heteroatoms.
		in heterocyclic ring assemblies, the assembly of highest seniority is that having lowest locants for the points of attachment between the rings within the assembly, consistent with the fixed numbering of the ring or ring system;
		in carbocyclic ring assemblies, the assembly of highest seniority is that having lowest numbers for the points of attachment between the systems within the assembly, consistent with the fixed numbering of the ring or ring system;
	www.chem.qmw.ac.uk /iupac/rssop/ss04.html (1029 words)

	Synthesis via N-Acyliminium Cyclisations of N-Heterocyclic Ring Systems related to Alkaloids (Site not responding. Last check: 2007-10-29)
		Alternatively, treatment of the acetal with 3.5% hydrochloric acid in diethyl ether afforded a 1:1 mixture of the monocyclic intermediate (R = H and OEt); this mixture was cyclized with 97% HCOOH (25 °C, 48 h) to give the pyrrolizidine ring (45%), and the exocyclic alkene (11%).
		Cyclisation of a 9:1 mixture of endocyclic: exocyclic enamides in anhydrous formic acid proceeded via a presumed chair-like transition state with the acyliminium moiety adopting a pseudo-equatorial position (Scheme 16), permitting an antiperiplanar addition to give a spirocyclic amide that led to a formal total synthesis of perhydrohistrionicotoxin.
		A highly stereoselective cyclisation leading to a seven-membered ring is known, and proceeds in excellent yield (Scheme 18).
	www.arkat-usa.org /ark/journal/2001/I01_General/404/0108_index.asp (1973 words)

	Appendix 2
		Six-membered heterocyclic ring with two or more heteroatoms at least one of which is oxygen (no nitrogen atom; see 44, 45) e.g.
		Five-membered heterocyclic ring with two or more heteroatoms at least one of which is oxygen (no nitrogen atom; see 50-51) e.g.
		Heteromonocyclic ring with at least one selenium atom (no N, O or S atoms) The trivial name selenophene (see 71, Se instead of O) is retained.
	www.chem.qmw.ac.uk /iupac/fusedring/app2.html (741 words)

	content2.html
		Using carbocyclic rings as a common point of reference, the effects of heteroatom substitution on the structure, properties, and reactivity of heterocycles will be discussed.
		Heterocyclic ring syntheses will be grouped into three broad categories: (1) Cyclization processes; (2) Concerted cycloaddition reactions; (3) Modification of existing rings.
		In addition to the extensive information on specific aspects of heterocyclic chemistry that will provided in the notes throughout the course, a brief tour of the important sources of information in heterocyclic chemistry will also be supplied.
	euch6f.chem.emory.edu /content2.html (380 words)

	Sulfur-Containing Heterocyclic Compounds (JECFA Food Additives Series 50)
		In the unlikely event that the nine flavouring agents in structural class III were to be consumed simultaneously on a daily basis, the estimated combined per capita intakes (1 µg/day in Europe and 11 µg/day in the USA) would not exceed the threshold for human intake for their structural class (90 µg per person).
		The fused-ring thiazole derivative, benzothiazole, is metabolized in guinea-pigs primarily by thiazole ring cleavage.
		Dithiazine is a six-membered, non-aromatic heterocycle containing two sulfur atoms (at the 1- and 3-positions) and one nitrogen (at the 5-position).
	www.inchem.org /documents/jecfa/jecmono/v50je12.htm (8095 words)

	2-hydroxymethylcyclopropylidenemethylpurines and -pyrimidines as antiviral agents - US Patent 6352991 (Site not responding. Last check: 2007-10-29)
		B is a heterocyclic ring derived from a purine or pyrimidine moiety.
		The numbering of the cyclopropylidenemethane moiety attached to the heterocyclic ring B is shown in Formulas 1 and 2.
		It is appreciated that heterocyclic rings containing hydroxy and amino groups are tautomeric with the corresponding oxo and imino compounds.
	www.patentstorm.us /patents/6352991.html (11725 words)

	Heat-sensitive transfer material - Patent 4873220
		A heat-sensitive transfer material as claimed in claim 1, wherein R.sup.3 and R.sup.4, which may be the same or different, each represents a fluorine atom, a chlorine atom, a bromine atom, a methoxy group, an ethoxy group, a propoxy group, a methyl group, a butyl group or a cyclohexyl group.
		Examples of divalent groups capable of forming a ring together with said nitrogen atom include a divalent amino group, an ether group, a thioether group, an alkylene group, a vinylene group, an imino group, a sulfonyl group, a carbonyl group, an arylene group, and a divalent heterocyclic group.
		R.sup.8 represents a chain or cyclic, preferably having from 1 to 6 carbon atoms, an aliphatic group (such as methyl, butyl a and cyclohexyl), an aryl group (such as phenyl) or a heterocyclic ring (such as 2-pyridyl, 2-imidazolyl, 2-furyl).
	www.freepatentsonline.com /4873220.html (4017 words)

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