An eco-friendly ultrasound-assisted one-pot three-component synthesis of 1,4-dihydropyrimido [1,2-a]benzimidazole derivatives catalyzed by maghnite-h⁺

A simple and efficient procedure is developed for the synthesis of 1,4-dihydropyrimido[1,2a]benzimidazole derivatives (DHPBz) via one-pot multi-component reaction of an aromatic aldehydes, ketones and 2-aminobenzimidazole, with use of a proton exchanged Algerian montmorillonite clay (Maghnite-H+) as green catalyst under ultrasound irradiation. This approach has the major advantages of short reaction time, good yields, easy operation, low energy consumption, and environmental friendliness. In addition, the solid non-toxic catalyst could be removed from the reaction mixture by simple filtration and recyclable without a lack of catalytic activity. All of the products were characterized by IR and NMR spectroscopy, MS, and elemental analysis.