Chemistry
5 Membered Ring
A 5 membered ring is a cyclic organic compound that contains five carbon atoms and at least one double bond. These rings are commonly found in natural products and pharmaceuticals due to their stability and unique reactivity. They can also be synthesized through various chemical reactions.
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3 Key excerpts on "5 Membered Ring"
eBook - PDF- Ramesh Chandra, Snigdha Singh, Aarushi Singh(Authors)
- 2020(Publication Date)
- Arcler Press(Publisher)
In addition to this, a latest article or book with respect to the heterocyclic chemistry is consisting of the significance of the heterocyclic compounds in the context of medicinal chemistry and natural products. Synthesis of Five- and Six-Membered Heterocyclic Compounds 211 7.3. COMPARISON WITH CARBOCYCLIC COMPOUNDS The molecules of the organic chemical compounds are developed from a backbone or framework of carbon atoms to which are attached oxygen, hydrogen (H), or the other kind of heteroatoms. Atoms of the carbon have distinctive properties of having the potential to combine with one another in order to form chains of atoms. When the tails of the chains are combined together into a ring, consequences of the cyclic compounds such as substance every so often are referred to as carbocyclic compounds or alicyclic compounds. Substitution of one or more of the ring carbon atoms in the molecules of a carbocyclic compound with a heteroatom given a heterocyclic compound. A conventional carbocyclic compound is cyclopentane (C 5 H 10 ), the molecular structure of which is shown by the formula: In which the chemical symbols that shows the atom of the elements and the lines shows the bonds among the atoms. In order to ease these kinds of formula every so often written in the simplified polygonal form, like: With respect to cyclopentane, in which each of the edge of the polygon shows a carbon atom (it is being acknowledged that the atoms of the hydrogen are linked to the atoms of carbon as needed). When one of the atoms of carbon of cyclopentane is substituted with the help of an atom of nitrogen, then the compound pyrrolidine, a chemical relative of pyrrole is created. The structural formula of the pyrrolidine can be written as shown below:
eBook - PDF- Alan R. Katritzky, J. M. Lagowski(Authors)
- 2013(Publication Date)
- Academic Press(Publisher)
C H A P T E R F I V E Five-Membered Rings Containing Two or More Heteroatoms I. N O M E N C L A T U R E A N D I M P O R T A N T C O M P O U N D S 1. Monocyclic Compounds Containing Annular Nitrogen Atoms Only The structures and names of the five-membered rings containing two or more nitrogen atoms are shown in diagrams (l)-(6). Two aromatic tautomeric forms are possible for unsymmetrically sub-stituted pyrazoles and imidazoles (e.g. 7 ^ 8). Two or three (in unsymmetrically substituted compounds) aromatic tautomeric forms are possible for 1,2,3- and 1,2,4-triazoles and tetrazoles (cf. Section 5.III.A.2). Ν I Η 1 pyrazole imidazole (or iminazole or glyoxaline) Ν—Ν il 1 1 V N 6 Ι 1,2,3-triazole 1,2,4-triazole Ν Η tetrazole pentazole Some pyrazoles are used pharmaceutical^, e.g. antipyrine (9). Many imidazoles are important biologically : ( 0 Histidine (10, Y = C0 2 H) is an essential amino-acid. (//) Histamine (10, Y = H) occurs in ergot and in putrefied proteins; among its many physiological effects is thought to be the development of allergies in humans, hence the importance of 'antihistamines'. 136 Five-Membered Rings with Two or More Heteroatoms 137 = ^ | M e Ν Ν x M e I Ph antipyrine (an antipyretic and analgesic) Et ο· Y ! H 2 NCH 10 histidine (Y = C 0 2 H ) histamine (Y = H) - CH 2 -12 Ν pilocarpine (alkaloid) H ^ •MI4 Y U NH ι I Η H.NCO 11 allantoin Ph + Τ NPh I Ph 13 nitron Nitron (13), a triazolium betaine, forms an insoluble nitrate which is used analytically. 2. Monocyclic Compounds Containing Annular Nitrogen and Oxygen or Sulphur Atoms By convention, oxazole and thiazole are used to name compounds with the heteroatoms in the 1,3-positions (14, Ζ = Ο, S) and isoxa-zole and isothiazole for the 1,2-isomers (15, Ζ = Ο, S). Four oxa-diazoles and four thiadiazoles are possible: the 1,2,3-, 1,2,4-, 1,2,5-, and 1,3,4-isomers.
eBook - PDFProgress in Heterocyclic Chemistry
A Critical Review of the 1995 Literature Preceded by Two Chapters on Current Heterocyclic Topics
- H. Suschitzky(Author)
- 1996(Publication Date)
- Pergamon(Publisher)
Chapter 5.1 Five-Membered Ring Systems Thiophenes & Se, Te Analogs Ronald K. Russell The R. W. Johnson Pharmaceutical Research Institute, Raritan, N J, USA Jeffery B. Press Galenica Pharmaceuticals, Inc., Frederick, MD, USA 5.1.1 INTRODUCTION As has been the case in previous years, the study of thiophenes has continued unabated in the past year. Of tremendous commercial import, the need to elucidate and improve the removal of sulfur-containing materials from petroleum necessitates further studies of the reactivities of thiophene and its derivatives with homogenous and heterogeneous catalysts. These on-going studies in transition-metal chemistry also require theoretical studies of the electronics, aromaticity and dipolarizability of thiophene-containing compounds which have implications into many areas of synthetic organic and medicinal chemistry. Although extended thiophene derivatives also have tremendous commercial potential as a result of their optochemical and super-conducting electronic properties, this subject was reviewed in detail in our last review and is not covered in this. One of the interesting aspects of thiophene chemistry is the relative ease and control of introducing substitution at either the 2- and/or the 3- position using routine organic synthetic methods. These derivatives allow study of the resultant electronic effects on the physical properties of thiophenes as well as provide access to novel molecules if the sulfur is removed. In this regard, the thiophene ring might be viewed as a four carbon delivery moiety with the sulfur atom as a protecting group. Since thiophene ring formation is readily accessible from linear materials using a variety of synthetic approaches, incorporation of thiophene into synthetic pathways provides a feasible method to produce useful regioselective results. Synthesis of fused thiophene derivatives continues to be an area of intense study by pharmaceutical and agricultural chemists.
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