Bicyclic 6 + 6 Systems: Advances in the Chemistry of Heterocyclic Compounds Incorporated Pyrimido[1,2-a]Pyrimidine Skeleton

The present review has highlighted the chemistry of pyrimido[1,2-a]pyrimidine compounds as one of the most important classes of heterocyclic systems. The main sections include: (1) The synthesis of pyrimido[1,2-a]pyrimidines, (2) reactivity of the substituents attached to the carbon and nitrogen atoms of the ring and (3) biological applications. A discussion demonstrated that the proposed mechanisms of unexpected synthetic routes were intended. The purpose of this review is to provide an overview of the chemistry of pyrimido[1,2-a]pyrimidines to date, in which the compounds should be widely applied in medicinal and pharmaceutical chemistry based on the significant, variable and potent biological results of pyrimidopyrimidine and pyridopyrimidine analogs. This survey will assist scientists in the organic and medicinal chemistry fields to design and develop procedures for the construction of new standard biological compounds.