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Heterocyclic Chemistry with Applications

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (31 March 2024) | Viewed by 10958

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Guest Editor
Department of Pharmacy, School of Life Sciences, Pharmacy & Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UK
Interests: free radical organic and polymer chemistry; heterocyclic and medicinal chemistry
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Special Issue Information

Dear Colleagues,

This Special Issue is dedicated to the broad range of applications of heterocycles, including in materials science and medicine. Recently famed applications include those in synthesis, with the Nobel Prize in Chemistry 2021 being jointly awarded to Benjamin List and David W.C. MacMillan for the development of asymmetric organocatalysis. Heterocycles are usually five or six-membered rings that are either fused or not fused onto other rings and that most often contain nitrogen atom(s) and/or oxygen atom(s). Many heterocycles have found applications as stable free radicals or as highly conjugated molecules in the photoredox catalysis of soft visible light-mediated reactions. I am therefore looking forward to receiving timeless research articles, communications, and reviews detailing the latest advances in heterocyclic chemistry with applications in medicinal, polymer, and synthetic chemistry, among others.

This Special Issue is running in parallel with another Special Issue called “Heterocycle Reaction” in our sister journal, Molbank: https://www.mdpi.com/journal/molbank/special_issues/Heterocycle_Reaction

Prof. Dr. Fawaz Aldabbagh
Guest Editor

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Keywords

  • heterocycles
  • medicinal chemistry
  • natural products
  • organic synthesis
  • radicals
  • reactive intermediates
  • synthetic methods

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Related Special Issue

Published Papers (5 papers)

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Research

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20 pages, 1743 KiB  
Article
Synthesis of 7α-Methoxy-7-(4-phenyl-1H-1,2,3-triazol-1-yl)acetamino-3′-arylthio-cephalosporic Acid Derivatives from 7-Aminocephalosporic Acid
by Wendy Y. Cun, Paul A. Keller and Stephen G. Pyne
Molecules 2023, 28(21), 7338; https://doi.org/10.3390/molecules28217338 - 30 Oct 2023
Viewed by 1300
Abstract
The aim of this project was to develop a synthetic protocol for the preparation of a cephamycin scaffold that would readily allow the synthesis of its analogues with variations at the C-7 amino group and the C-3′ position. We also aimed to develop [...] Read more.
The aim of this project was to develop a synthetic protocol for the preparation of a cephamycin scaffold that would readily allow the synthesis of its analogues with variations at the C-7 amino group and the C-3′ position. We also aimed to develop a method that avoided the use of toxic and potentially explosive diphenyldiazomethane. These aims were achieved via the synthesis of the novel α-bromo acetamide 18 which allowed functionalization at the α-bromo acetamide position by azide and then the introduction of a 4-phenyl-1H-1,2,3-triazol-1-yl moiety via a Cu(I)-catalysed azide–alkyne cycloaddition reaction with phenylacetylene. Palladium-catalyzed arylthioallylation reactions then allowed the introduction of 3′-arylthiol substituents. We also report for the first time the synthesis of the 4-methoxybenzyl ester of (6R,7S)-3-[(acetyloxy)methyl]-7-amino-7-methoxy-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid and the use of diphenyl trichloroacetimidate, instead of diphenyldiazomethane, and 4-methoxybenzyl trichloroacetimidate to prepare related 4-methoxybenzyl esters. The chemistry described, and several of the synthetic intermediates reported here, are potentially valuable methods and scaffolds, respectively, for further development of β-lactam antibiotics. Full article
(This article belongs to the Special Issue Heterocyclic Chemistry with Applications)
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17 pages, 6915 KiB  
Article
Regioselective Cyclic Iminium Formation of Ugi Advanced Intermediates: Rapid Access to 3,4-Dihydropyrazin-2(1H)-ones and Other Diverse Nitrogen-Containing Heterocycles
by Naděžda Cankařová and Viktor Krchňák
Molecules 2023, 28(7), 3062; https://doi.org/10.3390/molecules28073062 - 29 Mar 2023
Cited by 1 | Viewed by 1713
Abstract
Herein, advanced intermediates were synthesized through Ugi four-component reactions of isocyanides, aldehydes, masked amino aldehyde, and carboxylic acids, including N-protected amino acids. The presence of a masked aldehyde enabled acid-mediated deprotection and subsequent cyclization via the carbonyl carbon and the amide nitrogen. [...] Read more.
Herein, advanced intermediates were synthesized through Ugi four-component reactions of isocyanides, aldehydes, masked amino aldehyde, and carboxylic acids, including N-protected amino acids. The presence of a masked aldehyde enabled acid-mediated deprotection and subsequent cyclization via the carbonyl carbon and the amide nitrogen. Utilizing N-protected amino acid as a carboxylic acid component, Ugi intermediates could be cyclized from two possible directions to target 3,4-dihydropyrazin-2(1H)-ones. Cyclization to the amino terminus (westbound) and to the carboxyl terminus (eastbound) was demonstrated. Deliberate selection of building blocks drove the reaction regioselectively and yielded diverse heterocycles containing a 3,4-dihydropyrazin-2(1H)-one core, pyrazin-2(1H)-one, and piperazin-2-one, as well as a tricyclic framework with a 3D architecture, 2,3-dihydro-2,6-methanobenzo[h][1,3,6]triazonine-4,7(1H,5H)-dione, from Ugi adducts under mild reaction conditions. The latter bridged heterocycle was achieved diastereoselectively. The reported chemistry represents diversity-oriented synthesis. One common Ugi advanced intermediate was, without isolation, rapidly transformed into various nitrogen-containing heterocycles. Full article
(This article belongs to the Special Issue Heterocyclic Chemistry with Applications)
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18 pages, 2798 KiB  
Article
Pyrimidines-Based Heterocyclic Compounds: Synthesis, Cytoxicity Evaluation and Molecular Docking
by Mohamed A. El-Atawy, Najla A. Alshaye, Nada Elrubi, Ezzat A. Hamed and Alaa Z. Omar
Molecules 2022, 27(15), 4912; https://doi.org/10.3390/molecules27154912 - 1 Aug 2022
Cited by 14 | Viewed by 2537
Abstract
A variety of structurally different pyrimidines were synthesized. Elemental analysis, FT-IR, 1H NMR, and 13C NMR spectroscopy were used to confirm the chemical structures of all prepared compounds. The synthesized pyrimidines were screened against the growth of five human cancer cell [...] Read more.
A variety of structurally different pyrimidines were synthesized. Elemental analysis, FT-IR, 1H NMR, and 13C NMR spectroscopy were used to confirm the chemical structures of all prepared compounds. The synthesized pyrimidines were screened against the growth of five human cancer cell lines (prostate carcinoma PC3, liver carcinoma HepG-2, human colon cancer HCT-116, human breast cancer MCF-7, human lung cancer A-549), and normal human lung fibroblasts (MRC-5) using MTT assay. Most of the screened pyrimidines have anti-proliferative activity on the growth of the PC3 cell line. Compounds 3b and 3d were more potent than the reference vinblastine sulfate (~2 to 3 × fold) and they can be considered promising leads for treating prostate cancer disease. Moreover, the screened compounds 3b, 3f, 3g, 3h, and 5 were assessed according to the values of their selectivity index (SI) and were found to be more selective and safer than vinblastine sulfate. Furthermore, using in silico computational tools, the physicochemical properties of all pyrimidine ligands were assessed, and the synthesized compounds fall within the criteria of RO5, thus having the potential to be orally bioavailable. Full article
(This article belongs to the Special Issue Heterocyclic Chemistry with Applications)
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8 pages, 1428 KiB  
Article
Facile Synthesis of Tricyclic 1,2,4-Oxadiazolines-Fused Tetrahydro-Isoquinolines from Oxime Chlorides with 3,4-Dihydroisoquinoline Imines
by Kaikai Wang, Yanli Li, Wei Zhang, Rongxiang Chen, Xueji Ma, Mingyue Wang and Nan Zhou
Molecules 2022, 27(10), 3064; https://doi.org/10.3390/molecules27103064 - 10 May 2022
Cited by 2 | Viewed by 1871
Abstract
A mild and efficient strategy for the synthesis of tricyclic 1,2,4-oxadiazolines-fused tetrahydro-isoquinolines derivatives via [3 + 2] cycloaddition reaction is reported. The reactions provided the functionalized tricyclic 1,2,4-oxadiazolines in high yields (up to 96%). This protocol is simple and easy to handle. Moreover, [...] Read more.
A mild and efficient strategy for the synthesis of tricyclic 1,2,4-oxadiazolines-fused tetrahydro-isoquinolines derivatives via [3 + 2] cycloaddition reaction is reported. The reactions provided the functionalized tricyclic 1,2,4-oxadiazolines in high yields (up to 96%). This protocol is simple and easy to handle. Moreover, a gram-scale experiment further highlights the synthetic utility. The chemical structure of the product was determined by X-ray single-crystal structure analysis. A possible mechanism for this transformation is proposed to explain the reaction process. Full article
(This article belongs to the Special Issue Heterocyclic Chemistry with Applications)
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Review

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26 pages, 6570 KiB  
Review
Heterocyclic Iminoquinones and Quinones from the National Cancer Institute (NCI, USA) COMPARE Analysis
by Naemah Haji, Masoma Faizi, Panayiotis A. Koutentis, Michael P. Carty and Fawaz Aldabbagh
Molecules 2023, 28(13), 5202; https://doi.org/10.3390/molecules28135202 - 4 Jul 2023
Cited by 2 | Viewed by 2104
Abstract
This review uses the National Cancer Institute (NCI) COMPARE program to establish an extensive list of heterocyclic iminoquinones and quinones with similarities in differential growth inhibition patterns across the 60-cell line panel of the NCI Developmental Therapeutics Program (DTP). Many natural products and [...] Read more.
This review uses the National Cancer Institute (NCI) COMPARE program to establish an extensive list of heterocyclic iminoquinones and quinones with similarities in differential growth inhibition patterns across the 60-cell line panel of the NCI Developmental Therapeutics Program (DTP). Many natural products and synthetic analogues are revealed as potential NAD(P)H:quinone oxidoreductase 1 (NQO1) substrates, through correlations to dipyridoimidazo[5,4-f]benzimidazoleiminoquinone (DPIQ), and as potential thioredoxin reductase (TrxR) inhibitors, through correlations to benzo[1,2,4]triazin-7-ones and pleurotin. The strong correlation to NQO1 infers the enzyme has a major influence on the amount of the active compound with benzo[e]perimidines, phenoxazinones, benz[f]pyrido[1,2-a]indole-6,11-quinones, seriniquinones, kalasinamide, indolequinones, and furano[2,3-b]naphthoquinones, hypothesised as prodrugs. Compounds with very strong correlations to known TrxR inhibitors had inverse correlations to the expression of both reductase enzymes, NQO1 and TrxR, including naphtho[2,3-b][1,4]oxazepane-6,11-diones, benzo[a]carbazole-1,4-diones, pyranonaphthoquinones (including kalafungin, nanaomycin A, and analogues of griseusin A), and discorhabdin C. Quinoline-5,8-dione scaffolds based on streptonigrin and lavendamycin can correlate to either reductase. Inhibitors of TrxR are not necessarily (imino)quinones, e.g., parthenolides, while oxidising moieties are essential for correlations to NQO1, as with the mitosenes. Herein, an overview of synthetic methods and biological activity of each family of heterocyclic imino(quinone) is provided. Full article
(This article belongs to the Special Issue Heterocyclic Chemistry with Applications)
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