A metal-free and solvent-free method for the synthesis of quinazolin-4(3H)-ones is proposed by condensation cyclization of 2-aminobenzamides and aldehydes using 1-butyl-3-methylimida-zolium tetrafluoride ([Bmim]BF4) as ionic liquid catalyst. In this reaction, [Bmim]BF4 acts as both a catalyst and a solvent without need for additional catalysts and solvents. This method exhibits favorable functional group tolerance in substrates and affords a series of desired products in moderate to excellent yields. In addition, it is noteworthy that the reaction yield is still as high as 87% after [Bmim]BF4 is recycled at least four times.
