Silica Sulfuric Acid: An Eco‐Friendly and Reusable Catalyst for Synthesis of Benzimidazole Derivatives

Bahareh Sadeghi,Mahboobeh Ghasemi Nejad

doi:10.1155/2013/581465

Abstract

Silica sulfuric acid (SiO2‐OSO3H) as an eco‐friendly, readily available, and reusable catalyst is applied to benzimidazole derivatives synthesis under reflux in ethanol. The procedure is very simple and the products are isolated with an easy workup in good‐to‐excellent yields.

Highlights

Benzimidazole derivatives are found in many biologically active compounds possessing antiviral, antihypertension, and anticancer properties [1, 2]
Owing to the numerous advantages associated with this cheap and nonhazardous catalyst, under mild conditions, silica sulfuric acid has been explored as a powerful catalyst for various organic transformations [15, 16]. is solid acid has been used in synthesis of oxazolines and imidazolines [17], synthesis of 2,3-dihydroquinazolin-4(1H)-ones [18], synthesis of substituted pyrroles [19], chemoselective detritylation of 5 -tritylated nucleosides [20], and deprotection of oxime to carbonyls [21]
In continuation of our investigation about application of solid acids in organic synthesis [22, 23], we report a simple and efficient protocol for benzimidazole synthesis using a cheap and readily available SiO2-OSO3H catalyst. e efficiency of this acid is comparable with some other catalysts such as Me2S+BrBr−, P-TsOH, alumina-methanesulfunic acid, and BF3⋅OEt2

Summary

Introduction

Benzimidazole derivatives are found in many biologically active compounds possessing antiviral, antihypertension, and anticancer properties [1, 2]. Ere are several methods for benzimidazole synthesis; these compounds are conventionally prepared using condensation of o-phenylenediamine with carbonyl compounds in the presence of strong acids such as Me2S+BrBr−7, P-TsOH [9], Alumina-methanesulfnic acid [10], BF3⋅OEt2 [11], ceric(IV) ammonium nitrate [12]. Silica sulfuric acid (SiO2-OSO3H), a solid acid, is a versatile catalyst that makes reaction processes more convenient, more economic, and environmentally benign.

Results

Conclusion