ABSTRACT
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 β-dicarbonyl compounds. The procedure gave the products in high yields in very short reaction times at 100°C under solvent-free conditions. Also, this catalyst can be reused for five times without loss of its catalytic activity.
Acknowledgments
The authors are grateful to the Guilan University Research Council for the partial support of this work.