One-Pot Synthesis of 3,4-Dihydro-2(H)-Pyrimidinones Catalyzed by Reusable Acidic Choline-Based Ionic Liquids

Abstract A series of choline-based ionic liquids (CIL) have been synthesized in this work. The results suggested that both the cations and the anions have significant influences on their properties such as thermostabilities, acidities and their performances for the synthesis of 3,4-dihydro-2(H)-pyrimidinones. The optimized catalytic system based on the CIL [DMEA][HSO 4 ] for the Biginelli reactions benefits from the wide substrates tolerance, benign reaction conditions, easy work-up procedures, and the feasible reusability of the ionic liquid. Graphical Abstract The thermostabilities, acidities, and the catalytic activities for the Biginelli reactions are all follows the sequence of [DMEA][HSO 4 ] > [Choline] [HSO 4 ] > [DMEA][H 2 PO 4 ] > [Choline] [H 2 PO 4 ] .