Simple and efficient one-pot synthesis of 2-substituted benzimidazoles from θ-diaminoarene and aryl aldehydes

Article abstract of DOI:10.1080/00397911.2015.1083581

An easy and efficient one-pot condensation method for the synthesis of substituted benzimidazoles from θ-phenylenediamines with aryl aldehydes using urea hydrogen peroxide (UHP) and I2 in dimethylsulfoxide (DMSO) provides wide substrate scope with good to excellent yields and simple and quick isolation of the products.

Full text of DOI:10.1080/00397911.2015.1083581

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
This article was downloaded by: [University of Nebraska, Lincoln]
On: 29 August 2015, At: 02:03
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: 5 Howick Place,
London, SW1P 1WG
Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsyc20
A Simple and Efficient One-Pot Synthesis of 2-
Substituted Benzimidazoles from #-Diaminoarene and
Aryl Aldehydes
Mohan Lakshmi Punna Rao Alapatiab, Sridhar Rao Abburiab, Saratchandra Babu Mukkamalaa &
M. Krishnaji Raob
a Dept of Chemistry, GITAM Institute of Science, GITAM University, Visakhapatnam, India
b Quality Control Department, Unit-II, DIVIS Laboratories Ltd., Visakhapatnam, India
Accepted author version posted online: 20 Aug 2015.
Click for updates
To cite this article: Mohan Lakshmi Punna Rao Alapati, Sridhar Rao Abburi, Saratchandra Babu Mukkamala & M. Krishnaji
Rao (2015): A Simple and Efficient One-Pot Synthesis of 2- Substituted Benzimidazoles from #-Diaminoarene and Aryl
Aldehydes, Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
DOI: 10.1080/00397911.2015.1083581
To link to this article: http://dx.doi.org/10.1080/00397911.2015.1083581
Disclaimer: This is a version of an unedited manuscript that has been accepted for publication. As a service
to authors and researchers we are providing this version of the accepted manuscript (AM). Copyediting,
typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of
the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the
content, and all legal disclaimers that apply to the journal relate to this version also.
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
A Simple and Efficient One-Pot Synthesis of 2- Substituted Benzimidazoles from ϴ-
Diaminoarene and Aryl Aldehydes
Mohan Lakshmi Punna Rao Alapati1,2, Sridhar Rao Abburi1,2, Saratchandra Babu
Mukkamala1, M. Krishnaji Rao2
1Dept of Chemistry, GITAM Institute of Science, GITAM University, Visakhapatnam,
India, 2Quality Control Department, Unit-II, DIVIS Laboratories Ltd., Visakhapatnam,
India
Corresponding author to M. L. P. R. A. Alapati: E-mail: mohan_alapati@yahoo.com
Abstract
An easy and efficient one pot condensation method for the synthesis of substituted
benzimidazoles from ϴ-phenylenediamines with aryl aldehydes using UHP and I2 in
DMSO. This method provides wide substrate scope with good to excellent yields, simple
and quick isolation of the products
UHP / I2
NH2
OHC R2
N
70oC
NH2
R2
N
H
DMSO
KEYWORDS: Benzimidazole, ϴ-diaminoarene, urea hydrogen peroxide, iodine,
aldehydes
INTRODUCTION
Benzimidazole and its analogues have gained importance in modern drug discovery[1]
(Telmisartan, Dexlansoprazole). In particular, they have been in use as anticancer drug
1

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
agents[2], anti-ulcer,[3] anti-HIV,[4] antihypertensive,[5] analgesic,[6] antiviral,[7] anti-
inflammatory,[8] and are also very useful intermediates in organic synthesis. Numerous
synthetic methods are available for the construction of benzimidazoles on the basis of
condensation reaction between ϴ-diaminoarene and a carboxylic acids (or) esters (or) β-
Diketones (or) weinreb amide (or) aldehydes (or) acid chlorides (or) nitriles (or) aryl
alcohols in the presence of different catalysts such as PhI(OAc)2,[9] IBX,[10] silica-sulfuric
acid,[11] PEG-mediated catalyst-free condition,[12] BF3.OEt2,[13] UHP/SiO2-OPO3H2,[14]
MgI2,[15] DABAL-Me3,[16] HCl/H2O2,[17] and CAN/H2O2.[18] Further, several transition-
metal catalyzed reactions have been reported for the synthesis of 2-substituted
benzimidazoles such as CuCl,[19] Cu2O,[20] CoCl2,[21] Yb(OTf)3,[22] In(OTf)3,[23] and
WOx/ZrO2.[24] However, these methods suffer from several disadvantages like low yield,
harsh reaction conditions, use of expensive catalysts, occurrence of side reactions,
additional oxidation step, tedious work-up procedure and low reaction rate. The present
method aims at overcoming all these problems.
In the recent years, the versatility of urea hydrogen peroxide(UHP) reagent has been
disclosed in organic synthesis for instance, in the oxidation of aryl aldehydes to acids,[25]
sulfides to sulfoxides,[26] imines to nitrones,[27] preparation of heterocyclic N-oxides,[28]
solid-state oxidation,[29] and conversion of pyridines to N-oxides.[30]
In continuation of our studies in developing inexpensive and environmentally benign
methodologies for the synthesis of bioactive molecules, herein, we report UHP mediated
2