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N-Heterocycles
Published in Navjeet Kaur, Metals and Non-Metals, 2020
Benzimidazole is an important heterocycle known for its pharmacological activities and synthetic utility. It is used in a number of ways—as an anti-helminthic, anti-fungal, anti-histaminic, anti-HIV, anti-hypertensive, anti-ulcer, neuroleptic and cardiotonic. Extensive pharmacological and biochemical studies have confirmed that benzimidazoles are effective against many strains of microorganisms and hence have an important place among chemotherapeutic agents. The pharmacological importance of benzimidazoles is because of its close relationship with the structure of purines. The role of purines in biological system is well established and it has also been found that 5,6-dimethyl-1-(α-D-ribofuranosyl) benzimidazole is an integral constituent of Vitamin B12 [7–16].
Oxide Nanoparticles in Heterogeneous Catalysis
Published in Varun Rawat, Anirban Das, Chandra Mohan Srivastava, Heterogeneous Catalysis in Organic Transformations, 2022
Garima Sachdeva, Jyoti Dhariwal, Monika Vats, Varun Rawat, Manish Srivastava, Anamika Srivastava
Benzimidazoles are an important class of organic compounds because of their use in therapeutic and biological activities. Punniyamurthy et al. developed the methodology for synthesizing substituted benzimidazoles via intramolecular cyclization in the presence of CuO nanoparticles under air and ligand-free conditions in excellent yield (Figure 2.4). From an industrial point of view, this methodology is effective and eco-friendly as E-factor was decreased [17, 18]. The catalyst can be regained without loss in its selectivity and reactivity.
Core-shell magnetic microspheres as heterogeneous catalyst for synthesis of benzimidazole
Published in Journal of Coordination Chemistry, 2022
Linyan Yang, Lan Chen, Jinwei Guo, Cun Li, Tianming Jin
Benzimidazoles have a wide range of biological and pharmaceutical activities. Benzimidazole scaffolds are widely studied by synthetic chemists [1]. Many important drugs with different therapeutic uses contain benzimidazole rings [2], such as proton pump inhibitors (omeprazole), antihypertensive drugs (candesartan, telmisartan), antihistamines (Astemizole), antihelmintics (albendazole, mebendazole) and several other therapeutic agents, which are still under investigation, including antitumor and antiviral derivatives. Benzimidazoles are also indispensable intermediates in the synthesis of dyes and polymers [3], and have common uses in corrosion science [4], chemical sensing [5], and fluorescence [6]. Although there are many methods available in the literature, direct condensation-aromatization of 1,2-phenylenediamine and aldehyde is the most direct method for selective synthesis of 1,2-disubstituted benzimidazoles [7].
Green synthesis of benzimidazole derivatives under ultrasound irradiation using Cu-Schiff base complexes embedded over MCM-41 as efficient and reusable catalysts
Published in Journal of Coordination Chemistry, 2020
M. Bharathi, S. Indira, G. Vinoth, T. Mahalakshmi, E. Induja, K. Shanmuga Bharathi
Benzimidazole derivatives are synthesized in two general ways. The first process is coupling of o-phenylenediamines and carboxylic acids [17] or their derivatives (nitriles, orthoesters or imidates) [18] under strongly acidic conditions and sometimes along with very high temperatures. The second process involves two-step synthesis consisting of formation of Schiff base by condensation of o-phenylenediamines with aldehyde followed by oxidative cyclodehydrogenation using oxidative and catalytic reagents such as nitrobenzene [19], 1,4-benzoquinone [20], Ph(OAC)2 [21], Zn-proline [22], heteropoly acids [23], thionyl chloride-treatment [24], 2,3-dichloro-5-6-dicyanobenzoquinone (DDQ) [25], benzofuroxan [26], MnO2 [27], oxone [28], NaHSO3 [29], H2O2/HCl [30], Na2S2O5 [31], air [32], copper complex [33], Hauland natural zeolite [34], NaYzeolite [35], AlKIT-5 [36], etc. Some of these methods suffer from major drawbacks such as low yield, expensive catalysts, prolonged reaction times, difficulty in separation of the products from the reaction mixture, use of toxic solvents and requirement of more reagent. Therefore, the focus on designing economical, stable, recoverable, reusable and eco-friendly solid-supported heterogeneous catalyst for the synthesis of benzimidazole derivatives is important.
Synthesis, characterization and cytotoxic activity of organoruthenium(II)-halido complexes with 5-chloro-1H-benzimidazole-2-carboxylic acid
Published in Journal of Coordination Chemistry, 2019
Darko N. Pantić, Ljiljana E. Mihajlović-Lalić, Sandra Aranđelović, Siniša Radulović, Sanja Grgurić-Šipka
New strategies and formulations for designing improved metallotherapeutics include diverse variations of the arene moiety size as well as substitution of ligands and leaving groups. In that sense, benzimidazole and its derivatives are important (sub)structures for designing compounds with diverse biological activities and therapeutically useful agents (antitumor, antibacterial, antioxidant, antiviral, antifungal, antiinflammatory, analgesic, antihistaminic, etc.) [23]. Consequently, the interest in benzimidazole chemistry is increasing since the discovery of N-ribosyl-5,6-dimethylbenzimidazole as axial ligand in vitamin B12 [24]. Until now, many benzimidazole derivatives are used as drugs as they demonstrate antiparasitic (specifically anthelmintics, for example, albendazole, mebendazole and thiabendazole), antiulcer (proton pump inhibitors (PPIs), for example , omeprazole, lansoprazole and pantoprazole), antihypertensive (angiotensin II receptor blockers, e.g., candesartan cilexetil and telmisartan), antihistaminic (H1-receptor antagonists, e.g. astemizole and bilastine), anticancer (nitrogen mustard alkylating agents, e.g. bendamustine), antiemetic/antipsychotic (e.g. droperidol) activity, etc. (Figure 2) [25–29]. Furthermore, complexes of different transition metals with benzimidazole derivatives have also been synthesized showing significant biological activity, particularly anticancer and antimicrobial [25, 27, 30–35]. One promising pharmacophore containing benzimidazole nucleus is 5-chloro-1H-benzimidazole-2-carboxylic whose chemistry and biological activity were reported a decade ago [36–38].