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Prevention of the formation of advanced glycation end-products (AGEs) is a reliable approach to achieve control over hyperglycemia and the associated pathogenesis of diabetic vascular complications. In these terms, new synthetic approaches to 6-nitroazolo[1,5-a]pyrimidines have been developed on the basis of the promising antiglycation activity of their structural analogues, such as azolo[5,1-c][1,2,4]triazine-4(1H)-ones. A number of nitroazolopyrimidines were obtained by using nitration, chlorodeoxygenation, and amination reactions, and their antidiabetic properties were elucidated in vitro. It was shown that triazolo[1,5-a]pyrimidine-7(4H)-ones exhibit a higher antiglycation activity than the corresponding 7-alkylamino analogs and aminoguanidine, as the reference compound. It is suggested that this kind of activity can be associated with the chelating properties possessed by the synthesized 6-nitro-7-oxoderivatives. Furthermore, the compounds obtained were tested for their inhibitory activity against dipeptidyl peptidase 4 (DPP4), glycogen phosphorylase, and α-glucosidase in vitro, but their activities proved to be significantly inferior to those of the reference compounds.

A highly efficient PASE approach to a new class of polycyclic purine derivatives has been proposed. The strategy includes a consecutive reduction, auto-aromatization, and heterocyclization of the initial nitrobenzimidazopyrimidines obtained by a three-component condensation. It was shown that reduction of nitrobenzimidazopyrimidines by metals in acidic media was more efficient than heterogeneous hydro­genation. Novel derivatives of benz[4,5]imidazo[1,2-a]purines were obtained­ in good yields and the proposed structure was confirmed by X-ray crystal structure analysis. The obtained convergent benzimidazopurines combine two relevant medicinal chemistry scaffolds – benz­imidazole and purine.

A highly efficient approach to a new class of polycyclic 8-azapurines, benzo­[4,5]­imidazo­[1,2-a]­[1,2,3]­triazolo­[4,5-e]­pyrimidines (BITPs), with good photophysical characteristics is proposed. The approach comprises condensation of aminobenzimidazoles with 3-oxo-2-phenylazopropionitrile to form 3-(arylazo)­benzo­[4,5]­imidazo­[1,2-a]­pyrimidine-4-amines, which undergo oxidative cyclization by the catalytic action of copper­(II) acetate, resulting in BITPs with 73–84% yield. Spectral investigations demonstrated the fluorescent properties of BITPs, exhibiting good quantum yields (up to 60%) with maxima absorption at 379–399 and emission at 471–505 nm.