An efficient pot and step economic protocol for synthesis of pyrido[2,3-d]pyrimidine derivatives from a multicomponent aza-Diels–Alder reaction of uracil analogues, aromatic aldehydes and acetophenones in the presence of Na₂CO₃ in DMF was developed. The key step of the reaction is in situ generation of the reactive dienophile from aldehyde and acetophenone and their subsequent reaction with diene to give the desired product.