White Poplar Leaf-Derived Solid Acid Catalysts for Efficient Catalytic Synthesis of Dihydropyrimidinones

Abstract A carbon-based solid acid catalyst was successful prepared from white poplar leaves and p-toluenesulfonic acid in one-step proces. It could be used as catalyst for the coupling reaction of di-carbonyl compounds with urea and fatty aldehydes at 101°C in 4 h. The products of 3,4-dihydropyridine-2(1H)-ones (DHPMs) were isolated in good yields due to the high density of sulfonic acid groups (0.53 mmol/g). More importantly, the catalyst LP can be recycled at least eight times without significant decrease of catalytic activity. Facile operation, short reaction time, high activity and yields make the protocol to be a robust path to obtain dihydropyrimidinones.