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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Main Authors: Martin Sweeney, Darren Conboy, Styliana I. Mirallai, Fawaz Aldabbagh
Format: Article
Language:English
Published: MDPI AG 2021-05-01
Series:Molecules
Subjects:
Online Access:https://www.mdpi.com/1420-3049/26/9/2684
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spelling 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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