Simple, Efficient, and Applicable Route for Synthesis of 2-Aryl(Heteroaryl)-Benzimidazoles at Room Temperature Using Copper Nanoparticles on Activated Carbon as a Reusable Heterogeneous Catalyst

Palladium and Copper: Advantageous Nanocatalysts for Multi-Step Transformations

Metal nanoparticles have been deeply studied in the last few decades due to their attractive physical and chemical properties, finding a wide range of applications in several fields. Among them, well-defined nano-structures can combine the main advantages of heterogeneous and homogeneous catalysts. Especially, catalyzed multi-step processes for the production of added-value chemicals represent straightforward synthetic methodologies, including tandem and sequential reactions that avoid the purification of intermediate compounds. In particular, palladium- and copper-based nanocatalysts are often applied, becoming a current strategy in the sustainable synthesis of fine chemicals. The rational tailoring of nanosized materials involving both those immobilized on solid supports and liquid phases and their applications in organic synthesis are herein reviewed.

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in "click" reactions

In recent years, many inorganic silica/carbon-based and magnetic materials have been selected to arrest copper ions through a widespread range of anchoring and embedding methodologies. These inorganic supported nanocatalysts have been found to be efficient, environmentally friendly, recyclable, and durable. In addition, one of the vital issues for expanding new, stable, and reusable catalysts is the discovery of unique catalysts. The basis and foundation of this review article is to consider the recently published developments (2014-2019) in the synthesis and catalytic applications of copper supported by silica nanocomposites, carbon nanocomposites, and magnetic nanocomposites for expanding the "click" chemistry.

Copper nanoparticles supported on charcoal mediated one-pot three-component synthesis of N-substituted-2H-indazoles via consecutive condensation C–N and N–N bond formation

An efficient and straightforward protocol for direct synthesis of 2H-indazoles is achieved from consecutive condensation of 2-halobenzaldehydes, primary amines, and sodium azide catalyzed by heterogeneous copper nanoparticles on charcoal (Cu/C) is achieved. The recoverable heterogeneous copper nanoparticles on charcoal (Cu/C) catalyst exhibited an impressive activity for the title reaction without any additives (expensive ligands, etc.). A series of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily accessible starting materials by employing this protocol.

Design and synthesis of 2-phenyl benzimidazole derivatives as VEGFR-2 inhibitors with anti-breast cancer activity

Three new series of 2-phenyl benzimidazole-based derivatives were designed, synthesized, and evaluated for their in vitro cytotoxic activity against breast cancer (MCF-7) cell lines. Three compounds 8, 9, and 15 showed high cytotoxic activities, with IC₅₀ values of 3.37, 6.30, and 5.84 μM, respectively, while they showed comparable cytotoxicity to the standard drug doxorubicin against human normal cells, including nontumorigenic breast epithelial cell line (MCF-10F), skin fibroblast cell line (BJ), and lung fibroblast cell line (MRC-5). Six of the synthesized compounds were screened against vascular endothelial growth factor receptor 2 (VEGFR-2) where compounds 8, 9, 12, and 15 exhibited an outstanding potency in comparison with sorafenib, with IC₅₀ values of 6.7-8.9 nM. Molecular docking study assessed the good binding patterns of the most potent compounds with the reported conserved amino acids of VEGFR-2 active site.

A novel synthesis of 2-arylbenzimidazoles in molecular sieves-MeOH system and their antitubercular activity

Arylbenzimidazoles have been synthesized as antimycobacterial agents. An efficient synthesis has been developed for 2-arylbenzimidazoles from o-phenylenediamines and aromatic aldehydes in molecular sieves-methanol system. The methodology is straightforward to get 2-arylbenzimidazoles (3a-3z) in excellent yields with high chemoselectivity over 2-aryl-1-benzylbenzimidazoles (4a-4z). All these benzimidazole analogues were evaluated against M. tuberculosis in BACTEC radiometric assay. The compounds 4y and 4z exhibited potential antitubercular activity against M. tuberculosis H₃₇R_V, MIC at 16 µM and 24 µM respectively. The best compound of the series i.e. compound 4y was well tolerated by Swiss-albino mice in acute oral toxicity. Compound 4y possessing a diarylbenzimidazole core, can further be optimized for better activity.

Experimental and theoretical approving of anomeric based oxidation in the preparation of 2-sbstituted benz-(imida, oxa and othia)-zoles using [2,6-DMPy-NO2]C(NO2)3 as a novel nano molten salt catalyst

The synthesis of [2,6-DMPy-NO₂]C(NO₂)₃ as a novel NMS and its application in the synthesis of 2-sbstituted benz-(imida, oxa and othia)-zoles via a new mechanistic approach was supported by theoretical studies.

Synthesis and characterization of 2-substituted benzimidazoles and their evaluation as anticancer agent

In this work, we report a series of benzimidazole derivatives synthesized from benzene-1,2-diamine and aryl-aldehydes at room temperature. The synthesized compounds have been characterized on the basis of elemental analysis and various spectroscopic studies viz., IR, (1)H- and (13)C-NMR, ESI-MS as well by X-ray single X-ray crystallographic study. Interaction of these compounds with CT-DNA has been examined with fluorescence experiments and showed significant binding ability. All the synthesized compounds have been screened for their antitumor activities against various human cancer cell lines viz., Human breast adenocarcinoma cell line (MCF-7), Human leukemia cell line (THP-1), Human prostate cancer cell lines (PC-3) and adenocarcinomic human alveolar basal epithelial cell lines (A-549). Interestingly, all the compounds showed significant anticancer activity.

An efficient catalytic system based on 7,8-dihydroxy-4-methylcoumarin and copper(II) for the click synthesis of diverse 1,4-disubstituted-1,2,3-triazoles under green conditions

In this work, the combination of 7,8-dihydroxy-4-methyl coumarin (DHMC) as a novel bidentate O,O-chelating agent and copper(II) acetate monohydrate (2:1 molar ratio) has been found to form an efficient catalytic system. This catalyst provided good to excellent yields in the multi-component click synthesis of 1,4-disubstituted-1,2,3-triazoles by using various structurally diverse organic halides, different non-activated terminal alkynes, and sodium azide. This catalytic system eliminates the need for the isolation of the hazardous azide intermediates which are generated in situ. The reaction is carried out in aqueous phase at room temperature and it can be accelerated by sonication or by increasing the reaction temperature. Moreover, the reaction can be performed in large scale. It is noteworthy that DHMC is commercially available and that it can be easily synthesized with low cost materials.