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.

5-a]pyrimidines were obtained by the multicomponent reaction of aminoazoles, morpholino-nitroalkenes, and aromatic aldehydes in the catalysis of boron trifluoride etherate. The optimal reaction conditions were determined, and the formation of the target regioisomer was demonstrated. The pathway for multicomponent transformation, including the formation of azolyl-nitroalkene, was determined. Morpholinonitroalkenes were assumed to convert into the corresponding nitroalkynes during catalysis of boron trifluoride etherate. For a multicomponent reaction with 4-nitrobenzaldehyde, conditions have been proposed that exclude the formation of a side regioisomer.

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The reaction tolerance of the multicomponent process between 3-aminoazoles, 1-morpholino-2-nitroalkenes, and aldehydes was studied. The main patterns of this reaction have been established. Conditions for the oxidation of 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines were selected. Previous claims that the 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines could not be aromatised have now been refuted. Compounds with an electron-donor substituent at position seven undergo decomposition during oxidation. The phenomenon was explained based on experimental data, electro-chemical experiment, and quantum-chemical calculation. The mechanism of oxidative degradation has been proposed.

The present work reports on the synthesis of series of azolo[5,1‐c][1,2,4]triazines and derivatives of azoloazapurines. The synthesized compounds were tested in vitro for antibacterial activity against N. gonorrhoeae and antimycotic activity against Trichophyton interdigitale, Epidermophyton floccosum, Microsporum canis and Candida albicans. It was found that 10 compounds of the series of 3‐nitroazolo[5,1‐c][1,2,4]triazine‐4‐amines 4 exhibit high antibacterial activity (MIC≤15 μg/ml), but do not exhibit antimycotic activity. For compounds active against N. gonorrhoeae, a biological target was predicted from the pharmacophore search method and homologous modeling was carried out for it. The results of molecular docking using the constructed model of dihydrofolate reductase have a good correlation with in vitro tests. Refined docking showed the similarity of the leading compounds positions in the protein active site. The formation of stable non‐covalent bonds of the nitro group with the amino acid residues Lys34/Lys55 makes a major contribution to the orienting effect of ligands.