A Synthesis of 1,2,4-Triazolo[1,5-f]phenanthridines by Rearrangements of 1,2,5-Oxadiazoles Involving an NCN Sequence with the Imine Nitrogen in an Aromatic Heterocyclic Ring

Heterocycles ◽  
1990 ◽  
Vol 31 (5) ◽  
pp. 869 ◽  
Author(s):  
Giuseppe Cusmano ◽  
Gabriella Macaluso ◽  
Michelangelo Gruttadauria ◽  
Silvestre Buscemi
Keyword(s):  
Heterocyclic Ring ◽  
Imine Nitrogen ◽  
Aromatic Heterocyclic

scholarly journals Vibrational spectroscopic analyses of unique yellow feather pigments (spheniscins) in penguins

2013 ◽  
Vol 10 (83) ◽  
pp. 20121065 ◽  
Author(s):  
Daniel B. Thomas ◽  
Cushla M. McGoverin ◽  
Kevin J. McGraw ◽  
Helen F. James ◽  
Odile Madden
Keyword(s):  
Visible Spectrum ◽  
Heterocyclic Ring ◽  
Yellow Colour ◽  
Spectral Bands ◽  
Colour Palette ◽  
Macaroni Penguin ◽  
Stem Lineage ◽  
Non Destructive ◽  
Avian Family ◽  
Aromatic Heterocyclic

Many animals extract, synthesize and refine chemicals for colour display, where a range of compounds and structures can produce a diverse colour palette. Feather colours, for example, span the visible spectrum and mostly result from pigments in five chemical classes (carotenoids, melanins, porphyrins, psittacofulvins and metal oxides). However, the pigment that generates the yellow colour of penguin feathers appears to represent a sixth, poorly characterized class of feather pigments. This pigment class, here termed ‘spheniscin’, is displayed by half of the living penguin genera; the larger and richer colour displays of the pigment are highly attractive. Using Raman and mid-infrared spectroscopies, we analysed yellow feathers from two penguin species (king penguin, Aptenodytes patagonicus ; macaroni penguin, Eudyptes chrysolophus ) to further characterize spheniscin pigments. The Raman spectrum of spheniscin is distinct from spectra of other feather pigments and exhibits 17 distinctive spectral bands between 300 and 1700 cm −1 . Spectral bands from the yellow pigment are assigned to aromatically bound carbon atoms, and to skeletal modes in an aromatic, heterocyclic ring. It has been suggested that the penguin pigment is a pterin compound; Raman spectra from yellow penguin feathers are broadly consistent with previously reported pterin spectra, although we have not matched it to any known compound. Raman spectroscopy can provide a rapid and non-destructive method for surveying the distribution of different classes of feather pigments in the avian family tree, and for correlating the chemistry of spheniscin with compounds analysed elsewhere. We suggest that the sixth class of feather pigments may have evolved in a stem-lineage penguin and endowed modern penguins with a costly plumage trait that appears to be chemically unique among birds.

Imidazole Scaffold based Compounds in the Development of Therapeutic Drugs

2021 ◽  
Vol 21 ◽  
Author(s):  
Fanjie Hu ◽  
Lina Zhang ◽  
Kutty Selva Nandakumar ◽  
Kui Cheng
Keyword(s):  
Natural Products ◽  
Hydrogen Bonds ◽  
Biological Activities ◽  
Structural Characteristics ◽  
Imidazole Ring ◽  
Heterocyclic Ring ◽  
Pharmacological Activities ◽  
Therapeutic Drugs ◽  
Recent Developments ◽  
Aromatic Heterocyclic

: Imidazole has an important five-membered aromatic heterocyclic ring, which is available widely in natural products and synthetic molecules. The special structural characteristics of imidazole ring enable it to bind with various enzymes and receptors through hydrogen bonds, coordination, ion-dipole and cation-π interactions, hydrophobic effects, and Van der Waals forces. These interactions promote several biological activities involving anti-tumor, anti-inflammatory, anti-microbial and anti-viral properties. Herein, we review and discuss the recent developments occurred in using imidazole derivatives along with their special pharmacological activities for various diseases treatment.

THE PROTON RESONANCE SPECTRA OF FURAN AND PYRROLE

1959 ◽  
Vol 37 (6) ◽  
pp. 1056-1065 ◽  
Author(s):  
R. J. Abraham ◽  
H. J. Bernstein
Keyword(s):  
Fine Structure ◽  
Nmr Spectra ◽  
Heterocyclic Ring ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Surprising Result ◽  
Proton Resonance ◽  
Ring Compounds ◽  
Spin Coupling Constants ◽  
Aromatic Heterocyclic

Interpretation of the fine structure of the NMR spectra of some five-membered "aromatic" heterocyclic ring compounds indicates that spin coupling constants between adjacent protons on the ring and those across the ring are approximately equal. This is in contrast to the situation in six-membered rings where coupling constants between protons ortho to one another are much larger than those in the meta position.Quadrupole effects of the N14 nucleus in pyrrole broaden the NH signal but do not interfere with the spin coupling of the NH proton with other protons. The surprising result is obtained that the spin couplings of the NH proton with α and β protons in the ring are very nearly equal in magnitude.

Aromatic core-modified expanded porphyrinoids with meso-aryl substitutents

2002 ◽  
Vol 74 (11) ◽  
pp. 2045-2055 ◽  
Author(s):  
S. K. Pushpan ◽  
T. K. Chandrashekar
Keyword(s):  
Heterocyclic Ring ◽  
Synthetic Methodologies ◽  
Prosthetic Groups ◽  
Aromatic Heterocyclic

Porphyrins are the most widespread of all prosthetic groups found in Nature. The ubiquity of their functions in Nature led researchers around the globe to focus their attention on these highly colored macrocycles. The interdisciplinary interest generated by porphyrins resulted in the syntheses of modified porphyrins, which can be put to a variety of uses in medicine and industry. A brief overview of the synthetic methodologies resulting in the formation of aromatic meso-aryl-substituted core-modified aromatic heterocyclic ring-inserted expanded porphyrinoids like sapphyrins, smaragdyrins, rubyrins, hexaphyrins, heptaphyrins, and octaphyrins reported to date are discussed in this article.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

Diverse thiophenes as scaffolds in anti-cancer drug development: A concise review

2020 ◽  
Vol 20 ◽  
Author(s):  
Neha V. Bhilare ◽  
Pratibha B. Auti ◽  
Vinayak S. Marulkar ◽  
Vilas J. Pise
Keyword(s):  
Drug Development ◽  
Anticancer Agents ◽  
Heterocyclic Ring ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Cancer Drug ◽  
Active Compounds ◽  
Natural Origin ◽  
Concise Review ◽  
Anti Cancer

: Thiophenes are one among the abundantly found heterocyclic ring systems in many biologically active compounds. Moreover various substituted thiophenes exert numerous pharmacological actions on account of their isosteric resemblance with compounds of natural origin thus rendering them with diverse actions like antibacterial, antifungal, antiviral, anti-inflammatory, analgesic, antiallergic, hypotensives etc.. In this review we specifically explore the chemotherapeutic potential of variety of structures consisting of thiophene scaffolds as prospective anticancer agents.

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