Recent progress in the chemistry of bicyclic 6–6 systems: chemistry of pyrido[1,2-a]pyrimidines

The present review provides a study on the structural features, reactions, and synthetic methodologies of pyrido[1,2- a ]pyrimidines. Thus, the synthetic procedures and organic reactions since 2000 are described. The aim of this review is to give an overview of the diverse methodologies that have been reported on the chemistry of pyrido[1,2- a ]pyrimidines. The tautomeric forms of 2-methyl-3-chloro-9-hydroxypyrido[1,2- a ]pyrimidin-4-one are discussed, as well as, the biological importance and mechanistic pathways. Graphical abstract