Highly effective synthesis of 3, 4dihydropyrimidin2 (1H)ones using pyridiniumNsulfonic acid bisulfate as a dualfunctional catalyst

Acidic ionic liquid pyridiniumNsulfonic acid bisulfate ([PySO3H][HSO4]) has effectively catalyzed the production of 3, 4dihydropyrimidin2 (1H)ones via the condensation reaction of the arylaldehydes with βketoesters and urea under solventfree conditions. Due to the dualfunctionality of [PySO3H][HSO4] (bearing acidic and basic sites), it was highly effective and general catalyst for the reaction. Additionally, an attractive mechanism for the dualfunctionality of the catalyst was proposed.