Multi-walled carbon nanotubes sulfuric acid as a reusable heterogeneous solid acid catalyst for the rapid synthesis of imidazo[1,2-a]pyridines

Multi-walled carbon nanotubes sulfuric acid as a reusable heterogeneous stable solid acid catalyst was synthesized from a facile sulfonation of hydroxyl multi- walled carbon nanotubes with chlorosulfonic acid at 0 C during 2 h. The synthesized catalyst was found to be a highly efficient heterogeneous catalyst for the Groebke-type synthesis of imidazo(1,2-a)pyridines through a condensation reaction of an aldehyde, a 2-aminopyridine, and an isocyanide in methanol in excellent yields with short reaction times at room temperature. The catalyst could be easily recovered by simple filtration and reused without losing its activity.