The utility of pyrimidine derivatives in the construction of azolo[d]pyrimidine: part II-multi-nitrogen azole systems with potential biological applications

Abstract

In this review (part II), we continue our compilation of studies highlighting the use of the pyrimidine ring as a key core precursor for the construction of azolo[d]pyrimidine scaffolds containing more than one nitrogen atom in the azole moiety. Fusion of the azole ring owing to the presence of multiple nitrogen atoms onto the pyrimidine nucleus affords structurally diverse regioisomeric systems, including pyrazolo[3,4-d]pyrimidines, pyrazolo[4,3-d]pyrimidines, imidazolo[4,5-d]pyrimidines (purines) and [1,2,3]triazolo[4,5-d]pyrimidines (8-azapurines), depending on the position of the nitrogen atom within the fused heterocycle. This review provides a comprehensive overview of recent advances during the last decade (2015–2026) in the synthesis and biological applications of fused azolo[d]pyrimidine scaffolds (Part II). In addition, the results presented in this review highlight the importance of various azolo[d]pyrimidine derivatives as promising scaffolds for the development of new therapeutic agents.