Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles
This review article provides a perspective on the synthesis of alicyclic and heterocyclic ring-fused benzimidazoles, imidazo[4,5-<i>f</i>]benzimidazoles, and imidazo[5,4-<i>f</i>]benzimidazoles. These heterocycles have a plethora of biological activities with the iminoquinone...
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2021-05-01
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Online Access: | https://www.mdpi.com/1420-3049/26/9/2684 |
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doaj-cf3c5d4b66ac4f629516182baa09a1a82021-05-31T23:09:26ZengMDPI AGMolecules1420-30492021-05-01262684268410.3390/molecules26092684Advances in the Synthesis of Ring-Fused Benzimidazoles and ImidazobenzimidazolesMartin Sweeney0Darren Conboy1Styliana I. Mirallai2Fawaz Aldabbagh3School of Chemistry, National University of Ireland Galway, University Road, H91 TK33 Galway, IrelandDepartment of Pharmacy, School of Life Sciences, Pharmacy and Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UKSchool of Chemistry, National University of Ireland Galway, University Road, H91 TK33 Galway, IrelandSchool of Chemistry, National University of Ireland Galway, University Road, H91 TK33 Galway, IrelandThis review article provides a perspective on the synthesis of alicyclic and heterocyclic ring-fused benzimidazoles, imidazo[4,5-<i>f</i>]benzimidazoles, and imidazo[5,4-<i>f</i>]benzimidazoles. These heterocycles have a plethora of biological activities with the iminoquinone and quinone derivatives displaying potent bioreductive antitumor activity. Synthesis is categorized according to the cyclization reaction and mechanisms are detailed. Nitrobenzene reduction, cyclization of aryl amidines, lactams and isothiocyanates are described. Protocols include condensation, cross-dehydrogenative coupling with transition metal catalysis, annulation onto benzimidazole, often using CuI-catalysis, and radical cyclization with homolytic aromatic substitution. Many oxidative transformations are under metal-free conditions, including using thermal, photochemical, and electrochemical methods. Syntheses of diazole analogues of mitomycin C derivatives are described. Traditional oxidations of <i>o</i>-(cycloamino)anilines using peroxides in acid via the <i>t</i>-amino effect remain popular.https://www.mdpi.com/1420-3049/26/9/2684green chemistryhalogenheterocyclehydrogen peroxideimidazoleiodine |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Martin Sweeney Darren Conboy Styliana I. Mirallai Fawaz Aldabbagh |
spellingShingle |
Martin Sweeney Darren Conboy Styliana I. Mirallai Fawaz Aldabbagh Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles Molecules green chemistry halogen heterocycle hydrogen peroxide imidazole iodine |
author_facet |
Martin Sweeney Darren Conboy Styliana I. Mirallai Fawaz Aldabbagh |
author_sort |
Martin Sweeney |
title |
Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles |
title_short |
Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles |
title_full |
Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles |
title_fullStr |
Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles |
title_full_unstemmed |
Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles |
title_sort |
advances in the synthesis of ring-fused benzimidazoles and imidazobenzimidazoles |
publisher |
MDPI AG |
series |
Molecules |
issn |
1420-3049 |
publishDate |
2021-05-01 |
description |
This review article provides a perspective on the synthesis of alicyclic and heterocyclic ring-fused benzimidazoles, imidazo[4,5-<i>f</i>]benzimidazoles, and imidazo[5,4-<i>f</i>]benzimidazoles. These heterocycles have a plethora of biological activities with the iminoquinone and quinone derivatives displaying potent bioreductive antitumor activity. Synthesis is categorized according to the cyclization reaction and mechanisms are detailed. Nitrobenzene reduction, cyclization of aryl amidines, lactams and isothiocyanates are described. Protocols include condensation, cross-dehydrogenative coupling with transition metal catalysis, annulation onto benzimidazole, often using CuI-catalysis, and radical cyclization with homolytic aromatic substitution. Many oxidative transformations are under metal-free conditions, including using thermal, photochemical, and electrochemical methods. Syntheses of diazole analogues of mitomycin C derivatives are described. Traditional oxidations of <i>o</i>-(cycloamino)anilines using peroxides in acid via the <i>t</i>-amino effect remain popular. |
topic |
green chemistry halogen heterocycle hydrogen peroxide imidazole iodine |
url |
https://www.mdpi.com/1420-3049/26/9/2684 |
work_keys_str_mv |
AT martinsweeney advancesinthesynthesisofringfusedbenzimidazolesandimidazobenzimidazoles AT darrenconboy advancesinthesynthesisofringfusedbenzimidazolesandimidazobenzimidazoles AT stylianaimirallai advancesinthesynthesisofringfusedbenzimidazolesandimidazobenzimidazoles AT fawazaldabbagh advancesinthesynthesisofringfusedbenzimidazolesandimidazobenzimidazoles |
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1721418222964572160 |