A simple route for the synthesis of novel $$N$$ -alkyl-2-(alkylthio)-1 $$H$$ -imidazole derivatives

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A simple route for the synthesis of novel N -alkyl-2-(alkylthio)-1H -imidazole derivatives Ebrahim Kianmehr · Narges Shamsaei Zafarghandi · Mohammad Ghanbari

Received: 3 September 2012 / Accepted: 12 February 2013 © Springer Science+Business Media Dordrecht 2013

Abstract Novel N -alkyl-2-(alkylthio)-1H -imidazole derivatives were synthesized in a single step by an efficient and simple method in high yields. Readily available starting materials, mild reaction conditions, operational simplicity and novelty are the key advantages of this method. Besides their novel structures, these compounds may have important biological activities and industrial applications. Keywords Imidazoles · Heterocycles · 2-Alkylthioimidazoles · Thiocyanate · Library synthesis

tuted benzimidazole derivatives are irreversible proton pump inhibitors used for the prevention and treatment of gastric acid-related diseases [6–9] (Fig. 1). As a result, several strategies have been explored for the preparation of these imidazole derivatives. One such route consists of the introduction of substituents prior to imidazole ring formation. Suitable precursors may, however, be difficult or impossible to synthesize. Many substituents are also sensitive and do not tolerate the reaction conditions for the cyclization. A more general strategy is to introduce substituents to the preformed ring. However, a limitation of such an approach is often the lack of regioselectivity [10–14].

Introduction Substituted imidazoles are key substructures present in many compounds possessing interesting pharmacological properties [1,2]. 2-Mercapto imidazoles are an important class of imidazoles that are encountered in a number of natural and non-natural biologically active compounds. For example, 2-(benzylthio)-4, 6-dichloro-1-[(2-hydroxyethoxy)methyl] benzimidazole (1) has been found to have antiviral activity [3] and 1-(ter t-butyl)-3-(2-((2-methoxy-5-nitrobenzyl)thio)-1propyl-1H -benzo[d]imidazol-5-yl)urea (2) is used as a luteinizing hormone-releasing hormone (LHRH) antagonist [4]. N -Methylimidazole (3) is a potent human histamine H3 antagonist [5]. Tenatoprazole (4), Omeprazole (5), Pantoprazole (6), Rabeprazole (7) and Lansoprazole (8), substiElectronic supplementary material The online version of this article (doi:10.1007/s11030-013-9430-5) contains supplementary material, which is available to authorized users. E. Kianmehr (B) · N. Shamsaei Zafarghandi · M. Ghanbari School of Chemistry, College of Science, University of Tehran, Tehran, Iran e-mail: [email protected]

Results and discussion Considering the above reports, the development of new and simple synthetic methods for the selective and efficient substitution of imidazole ring fragment with alkylthio groups will be a beneficial and interesting challenge. As part of our current studies on the development of efficient methods for the preparation of heterocyclic compounds [15–18], herein we report a novel procedure for the synthesis of wide range of N -alkyl-2-(alkylthio)-1H -imidazol