Efficient synthesis of dihydropyrido[4,3-d]pyrimidines by microwave-promoted three-component aza-Diels–Alder reaction

A microwave-promoted solvent- and catalyst-free aza-Diels–Alder reaction is described. 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil reacts with aldehyde and amine inside a microwave reactor to produce dihydropyrido[4,3-d]pyrimidine derivatives in excellent yield and within a very short time.