Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

&nbsp;

&nbsp;

VIT University

We have developed an efficient, parallel synthesis of 2-substituted aminobenzimidazoles via intramolecular ring closing reactions of imidazolium ion tag immobilized o-phenylenediamine with various isothiocyanates. The methodology is based on the attachment of 4-fluoro-3-nitro benzoic acid into the imidazolium ion tag, which enables the SNAr reactions with different amines followed by neutral reduction to furnish o-phenylenediamines under microwave irradiation. The substituted isothiocyanates are reacted with o-phenylenediamines to form monothiourea, which is further activated by methyl iodide to undergo desulfurization in one pot manner. The ionic liquid bound 2-substituted aminobenzimidazoles were finally cleaved from the support with sodium methoxide to generate target compounds in good yields and high purities with two points of structural diversity. This synthetic protocol has promising features of extremely short reaction time, operational simplicity, good yields, as well as&nbsp;widespread applications, leading to a facile and straightforward admittance to structurally diverse 2-substituted aminobenzimidazole analogues with potential bioactivities.

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Tetrahedron

Novel approach towards 2-substituted aminobenzimidazoles on imidazolium ion tag under focused microwave irradiation<ul><li><a href="https://www.semanticscholar.org/author/K.-Chanda/144658483">K. Chanda</a>, <a href="https://www.semanticscholar.org/author/Barnali-Maiti/49226496">Barnali Maiti</a>, author <a href="https://www.semanticscholar.org/author/Chung%E2%80%90Ming-Sun/2503061">Chung‐Ming Sun</a></li></ul>

In a study aimed at developing a novel concise approach to the benzimidazole-pyrrolo[1,2-a]quinoxaline core of medicinal interest, a Pictet–Spengler reaction has been identified that gives direct access to the target compound on soluble polymer support under focused microwave irradiation. The pyrrole moiety has been introduced on polymer immobilized benzimidazole derivatives by SNAr diversification which subsequently transformed to the title compounds viareduction followed by Pictet–Spengler cyclisation with various ketones in good yields and excellent purity. The work described here demonstrates the versatility of the base mediated SNAr reaction coupled with Pictet–Spengler cyclisation in the construction of novel heterocycles.

New Journal of Chemistry

Novel approach towards the synthesis of skeletally diverse benzimidazole-pyrrolo[1,2-a]quinoxaline by SNAr/Pictet–Spengler reaction under focused microwave irradiation†<a href="https://pubs.rsc.org/en/results?searchtext=Author%3ABarnali%20Maiti">Barnali Maiti</a>a  and  <a href="https://pubs.rsc.org/en/results?searchtext=Author%3AChung-Ming%20Sun">Chung-Ming Sun</a>*a

An efficient soluble polymer-supported method has been developed for the parallel synthesis of substituted benzimidazole linked benzoxazoles using focused microwave irradiation. The key step involves the amidation of 4-hydroxy-3-nitrobenzoic acid with polymer-immobilized o-phenylenediamine. Application of mild acidic conditions promoted the ring closure to furnish the benzimidazole ring. After hydrogenation of the nitro-group to amine, the resulted polymer conjugates underwent efficient ring closure with various alkyl, aryl and heteroaryl isothiocyanates to generate the polymer-bound benzimidazolyl benzoxazoles. The polymer-bound compounds were finally cleaved from the support to furnish benzimidazole linked benzoxazole derivatives. The efficacy of the resultant angular bis-heterocyclic library was studied against vascular endothelial growth factor receptor (VEGFR-3). The preliminary screening of these novel compounds exhibits moderate to high inhibition (IC50 = 0.56–1.42 μM). This protocol provides an easy access to novel angular bis-heterocycles which have potential for the discovery of novel leads for targeted cancer therapeutics.

Organic & Biomolecular Chemistry

Polymer supported synthesis of novel benzoxazole linked benzimidazoles under microwave conditions: In vitro evaluation of VEGFR-3 kinase inhibition activity†<a href="https://pubs.rsc.org/en/results?searchtext=Author%3AKaushik%20Chanda">Kaushik Chanda</a>,a   <a href="https://pubs.rsc.org/en/results?searchtext=Author%3ABarnali%20Maiti">Barnali Maiti</a>,a   <a href="https://pubs.rsc.org/en/results?searchtext=Author%3AGorakh%20S.%20Yellol">Gorakh S. Yellol</a>,a   <a href="https://pubs.rsc.org/en/results?searchtext=Author%3AMing-Hsien%20Chien">Ming-Hsien Chien</a>,b   <a href="https://pubs.rsc.org/en/results?searchtext=Author%3AMin-Liang%20Kuo">Min-Liang Kuo</a>c  and  <a href="https://pubs.rsc.org/en/results?searchtext=Author%3AChung-Ming%20Sun">Chung-Ming Sun</a>*a

&nbsp;<figure class="image image_resized" style="width:81.17%;"><img src="https://pubs.acs.org/na101/home/literatum/publisher/achs/journals/content/orlef7/2009/orlef7.2009.11.issue-21/ol901857h/production/images/medium/ol-2009-01857h_0006.gif" alt="Abstract Image"></figure>A novel ionic liquid (IL) supported, green synthetic protocol has been developed toward the synthesis of oxo and thio hydantoin analogues tethered with tetrahydro-β-carboline by the use of focused microwave irradiation. IL-bound tryptophan underwent a Pictet−Spengler reaction with various carbonyl compounds to generate the IL- immobilized tetrahydro-β-carbolines in aqueous isopropanol media. Subsequent reaction of substituted tetrahydro-β-carboline derivatives with various isocyanates and isothiocyanate provided a three-dimensional combinatorial library in a traceless fashion

Organic Letters

Traceless Synthesis of Hydantoin Fused Tetrahydro-β-carboline on Ionic Liquid Support in Green Media<ul><li><a href="https://pubs.acs.org/action/doSearch?field1=Contrib&amp;text1=Barnali++Maiti">Barnali Maiti</a></li><li><a href="https://pubs.acs.org/action/doSearch?field1=Contrib&amp;text1=Kaushik++Chanda">Kaushik Chanda</a></li><li><a href="https://pubs.acs.org/action/doSearch?field1=Contrib&amp;text1=Chung-Ming++Sun">Chung-Ming Sun</a>*</li></ul>

In this study, a highly efficient two-component [3 + 2] cycloaddition reaction of substituted aryl aldehydes with 4-toluenesulfonylmethyl isocyanide (TosMIC) in the presence of 2 equiv of potassium phosphate as a base to 5-substituted oxazoles were established in a isopropanol medium under microwave irradiation. However, using 1 equiv of K3PO4 as a base resulted in the diastereoselective synthesis of 4,5-disubstituted oxazolines under identical reaction conditions. The foremost benefits of these protocols are the moderate-to-excellent yields with good functional group compatibility, simple experimental procedure, inexpensive readily available starting materials, nonchromatographic purification, and high bond-forming efficiency. The synthetic manipulation reported herein represents a cleaner route to the sustainable preparation of 5-substituted oxazoles and diastereoselective 4,5-disubstituted oxazolines derivatives.

Fulltext

ACS Omega

A Facile Microwave-Assisted Synthesis of Oxazoles and Diastereoselective Oxazolines Using Aryl-Aldehydes, p-Toluenesulfonylmethyl Isocyanide under Controlled Basic Conditions<ul><li>Narasimharao Mukku</li><li>Prabhakara Madivalappa Davanagere</li><li>Kaushik Chanda</li><li>Barnali Maiti*</li></ul>

Benzimidazole and its derivatives are regarded as an important heterocyclic motif that exhibits a wide range of pharmaceutical applications including anticancers, antihypertensives, antivirals, antifungals, anti-HIVs, anti-convulsants, and anti-diabetics. In view of their wide ranging activities, the synthesis of benzimidazoles and its derivatives remain a primary focus for synthetic chemistry communities. Till date numerous reports especially on the synthesis of 2-arylbenzimidazoles have been published but lack of knowledge on the detailed synthetic reports of two important derivatives such as 2-aminobenzimidazoles, and 2-(alkyl/aryl)thio benzimidazoles still persists. However, owing to fast developing benzimidazole containing new drugs numerous reports have appeared on the synthesis of this privileged scaffold. In this review, efforts have bee

Current Organic Synthesis

Synthesis and Medicinal Applications of Benzimidazoles: An OverviewRajasekhar S, Maiti B,<a href="https://research.vit.ac.in/researcher/balamurali-m-m">Balamurali M M</a>, <a href="https://research.vit.ac.in/researcher/kaushik-chanda">Kaushik Chanda</a>