Efficient Synthesis of Pyrimido[1,2-a]Benzimidazoles and Ethyl Pyrimido[1,2-a]Benzimidazole-3-Carboxylates Using Bronsted Acidic Ionic Liquid Supported on Nanoporous Na+-Montmorillonite

摘要

In this work, nanoporous sodium montmorillonite clay (Na+-MMT) was successfully modified with 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sulfate (Na+-MMT-[pmim]HSO4). This immobilized acidic ionic liquid showed excellent catalytic activity for the synthesis of pyrimido[1,2-a]benzimidazoles and ethyl pyrimido[1,2-a]benzimidazole-3-carboxylates via three-component reactions between aldehydes, 2-aminobenzimidazole and malononitrile or beta-dicarbonyl compounds. The procedure gave the products in high yields in very short reaction times at 100 degrees C under solvent-free conditions. Also, this catalyst can be reused for five times without loss of its catalytic activity.