Studies on –SO 3 H Functionalized Brønsted Acidic Imidazolium Ionic Liquids (ILs) for One-Pot Two Step Synthesis of 2-styrylquinolines

After knowing their thermal stabilities, the catalytic activity was observed for the preparation of 2-styrylquinolines by following a consecutive Friedländer and Knoevenagel reactions in solvent-free thermal energy. The acidity order ([Dsim][OOCCF 3 ]>[Dsim][OTs]>[Dsim][OOCCl 3 ]> [Msim][OOCCF 3 ]) of three ILs was consistent with their activity order observed in the acid-catalyzed synthesis of 2-styrylquinolines under solvent-free condition at 90° C except [Dsim][OTs].

The best catalytic activity showed by 25 mol% of [Dsim][OOCCF 3 ] IL. The less acidic ILs required 50 mol% to give good yields of 2-styrylquinolines under the optimized conditions.