Abstract
The present paper introduces a simple and efficient method for the synthesis of substituted benzimidazoles by heterocyclization of differento-phenylenediamines and substituted aromatic carboxylic acid/aldehyde in the presence of zirconyl nitrate as catalyst in ethanol under reflux, which produced excellent yield of corresponding benzimidazoles in a short reaction time with reusability of catalyst.
Highlights
Heteroaromatic compounds have awestruck significant attention in the design of biologically active molecules and advanced organic materials [1, 2]
A variety of catalysts such as homogeneous Lewis acids [20], pyridinium-p-toluenesulfonate [20], ultrasonic [21], I2/KI/K2CO3/H2O [22], ionic liquids [23], sulfonium bromide [24], and polyaniline-sulfate [25] and a tandem oxidation process [26] have been used for the synthesis of benzimidazole derivatives
We examined the cyclocondensation of o-phenylenediamine with different substituted aromatic carboxylic acid/aldehydes using zirconyl nitrate/Zr(IV) as a Lewis acid catalyst for the synthesis of substituted benzimidazoles
Summary
Heteroaromatic compounds have awestruck significant attention in the design of biologically active molecules and advanced organic materials [1, 2]. The presence of even a small amount of water stops the reactions; and most Lewis acids immediately react with water rather than substrates [28] In this context, in the present study, we report here the use of zirconyl nitrate as eco-friendly water-soluble Lewis acid catalyst for the synthesis of substituted benzimidazole. In the continuation of our interest in synthesis of nitrogen-containing heterocyclic compounds [32], wefoundedthe application of ZrO(NO3) as a Lewis acid catalyst for the synthesis of substituted benzimidazoles viathe condensation reaction between o-phenylenediamine and aldehyde, carboxylic acid derivatives (Scheme 1)
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