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. Synthesis of 2-aryl benzimidazoles 3a-p.

Synthesis of Multifunctionalised 2-Substituted Benzimidazoles Using Copper (II) Hydroxide as Efficient Solid Catalyst

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16 synthesis and reactions of 2-styrylbenzimidazoles

We have developed a short and efficient method for the synthesis of 2-aryl benzimidazoles from 1,2-phenylenediamines and aryl aldehydes using H5IO6-SiO2 as catalyst. The mild reaction condition, low cost, easy workup procedure and good to excellent yields as well as the scope for using wide substrates make our methodology a valuable contribution to the existing processes for synthesis of benzimidazole derivatives. Among 18 derivatives, newly synthesized 5-substituted derivatives exhibited excellent activity against MCF7 and HL60 cell lines. The overall activities for all the derivatives tested were found in micromolar range. The current study provides better insight into the designing of more potent anticancer agents in the future.

4.1. General Procedure for the Synthesis of 2-Aryl Benzimidazole 3a-p in Water

Benzimidazoles are synthesized from amidines through a copper-catalyzed C–H functionalization/C–N bond-forming process. The method tolerates a broad range of functional groups and provides the benzimidazoles in up to 89 % yield. Best results are obtained by using 15 mol % Cu(OAc)2, 2–5 equivalents of HOAc as additive, and oxygen as the stoichiometric reoxidant.

Synthesis of benzimidazoles - Organic Chemistry Portal

. A plausible mechanism for the synthesis of multifunctionalised benzimidazoles using Cu(OH)2.

In order to further development of synthetic route of benzimidazoles under green reaction conditions, here, we devoted our effort for the synthesis of 2-aryl benzimidazole derivatives in water as a green solvent as well as solvent-free conditions (Scheme 1).

3a (, entry 9). Although, the reaction gave high to excellent yields in organic solvents, but using water is the most advantageous to this method (, entries 14 - 19). After optimizing the reaction condition, to explore the scope and generality, the synthesis of benzimidazole derivatives 3a-p were carried out through the reaction of 1,2-phenylenediamine derivatives and a wide diversity of arylidenemalononitrile in high yields (). Interestingly, we observed that the position and nature of substitution on the ring of arylidenemalononitrile did not make much difference in reactivity, indicating the wide scope of this methodology.

Microwave-Assisted Synthesis of Benzimidazoles and …

. Synthesis of multifunctionalised 2-substituted benzimidazoles using Cu(OH)2.

A new series of substituted benzimidazoles as 1-(substituted methyl)-2-(substituted phenyl) benzimidazoles were synthesized and characterized. The compounds were evaluated for anti-inflammatory and antibacterial activity. All the compounds exhibited significant to moderate antiinflammatory and antibacterial activities.

Green and High Efficient Synthesis of 2-Aryl Benzimidazoles: Reaction of Arylidene Malononitrile and 1,2-Phenylenediamine Derivatives in Water or Solvent-Free Conditions

. Room temperature synthesis of multifunctionlised benzimidazoles using copperhydroxide solid catalyst.
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  • Expedient synthesis of benzimidazoles using amides - …

    T1 - Synthesis of 1-alkoxy-2-alkyl-benzimidazoles from 2-nitroanilines via tandem N-alkylation-cyclization-O-alkylation

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    Abstract: A photocatalytic method has been developed for the efficient synthesis of functionalized benzimidazoles

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Synthesis of N-Alkyl-2-thiomethyl Benzimidazoles: A …

Many heterogeneous catalysts [32,33] and expensive Co(III) salen complexes [48] were used in the synthesis of various benzimidazoles. But all they have not achieved the products using aliphatic aldehydes. The present catalyst is simple, recyclable, green catalyst and more convenient than many catalysts presented in the above introduction. These catalysts were also found to be very active in the synthesis of benzimidazoles using an acid sensitive furfuraldehyde (3f) and bulky naphthaldehyde (3g), also worked well. Various substituted aldehydes have been used with similar success to provide the corresponding benzimidazoles in high yields (80% - 99%).

Synthesis of 2-Substituted Benzimidazoles and Bis | …

Encouraged by these results, we examined several substituted aldehydes including aromatic, heteroaromatic and aliphatic groups, which underwent smooth conversion to afford a wide range of benzimidazoles (). Aromatic aldehydes containing both electron-donating and electron-withdrawing groups worked well in this reaction. Unfortunately metal hydroxides are not explored much in the synthesis of various benzimidazoles. It was found that transition metal oxide is more effective for oxidation than the corresponding zero-valent metal powders. Open air and copper hydroxide both may be sources for the oxidation process. Here, it seems that copper hydroxide solid catalyst is acting as bifunctional like Lewis acid as well as oxidative reagent.

ChemInform Abstract: The Synthesis of Benzimidazoles …

In addition we have also carried out scale up experiments with 1.08 g of o-phenylenediamine and 1.27 g of benzaldehyde using 10 mol% of Copper hydroxide catalyst at room temperature in methanol. The Cu(OH)2 catalyst gave 98% of product 3a, that is almost similar to the yield obtained in Entry a, indicating that the catalyst could be easily used on a large scale. In the present work, the catalytic activity of the Cu(OH)2 has been studied for synthesis of multifunctionalised benzimidazole derivatives at room temperature. It has been found that these commercially available catalysts are very cheap, recyclable and showed superior activity at room temperature than Co(III) salen [48], and cheaper than many other expensive heterogeneous catalysts [32,33]. All the synthesized compounds (3a-3v) colour, melting points were checked and characterized by using IR and 1H-NMR spectra data was given below.

Synthesis of imidazoles - Organic Chemistry Portal

AzizollahHabibi,YousefValizadeh,MarjanMollazadeh,AbdolaliAlizadeh, (2015) Green and High Efficient Synthesis of 2-Aryl Benzimidazoles: Reaction of Arylidene Malononitrile and 1,2-Phenylenediamine Derivatives in Water or Solvent-Free Conditions. ,05,256-263. doi:

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