Uncatalyzed synthesis of new substituted dihydro-2H-dipyrimido[1,2-a,4,5-d]pyrimidine-2,4(3H)-dione

A convenient and new method has been developed for the synthesis of highly substituted dihydro-2H-dipyrimido[1,2-a,4,5-d]pyrimidine-2,4(3H)-dione derivatives by one-pot three-component reactions of barbituric acid, aromatic aldehydes and 2-aminopyrimidine in ethanol under reflux condition without the support of any catalyst. The benefits of this protocol are catalyst-free, clean reaction procedure and providing excellent yields, and the use of ethanol as a solvent, which has been measured to be comparatively environmentally benign.