highly effective synthesis of 3, 4-dihydropyrimidin-2 (1h)-ones using pyridinium-n-sulfonic acid bisulfate as a dual-functional catalyst

Acidic ionic liquid pyridinium-n-sulfonic acid bisulfate ([py-so3h][hso4]) has effectively catalyzed the production of 3, 4-dihydropyrimidin-2 (1h)- ones via the condensation reaction of the arylaldehydes with β-ketoesters and urea under solvent-free conditions. due to the dual-functionality of [py- so3h][hso4] (bearing acidic and basic sites), it was highly effective and general catalyst for the reaction. additionally, an attractive mechanism for the dual-functionality of the catalyst was proposed.