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Convenient methods for the synthesis of three monomers based on functionalized (bi)pyridines with using “1,2,4-triaizine” methodology have been developed.

A convenient synthesis of 1,2,4-triazines bearing the moieties of (hetero)arylhydrazines at the position of C5 of the 1,2,4-triazine core is reported.

An efficient synthetic approach towards 5-arylethynyl-1,2,4-triazines via direct C-H-functionalization of 5-H-1,2,4-triazines in reaction with lithium acetylenes is reported.

Two ethyleneglycol esters of 1-pyrene carboxylic acid were studied as chemosensors for the fluorescence “turn-off” detection of two nitro-containing analytes, such as antiviral drug Riamilovir (Triazavirin ®) and herbicidal agent dinitro-ortho-cresol (DNOC). In both cases the dramatic fluorescence quenching was observed with quenching constants as high as 3·104 M-1 and limits of detection (LOD) as low as 100 ppb.

A convenient method for the obtaining of 3,6-diaryl-1,2,4-triazines substituted with residues of higher alcohols in the position of C5 via the ipso-substitution of cyano group in under the solvent free conditions was reported. This method indicates a new example for the functionalization of the 1,2,4-triazines via the substitution of the cyano group.

Two mutually complementary synthetic approaches towards 3- and 3,4-disubstituted 1-(2-pyridyl) isoquinolines were studied. The aryne-based method was successfully used for the obtaining of the corresponding the 3-cyano-1-(2-pyridyl)isoquinolines in one step/pot reaction, while it is unacceptable for the obtaining of other 1-(2-pyridyl)isoquinolines. The enamine-based approach was successfully applied for the synthesis of other 1-(2-pyridyl)isoquinolines, while it was unacceptable for the obtaining of 3-cyano-1-(2-pyridyl)isoquinolines.

As a model of metabolic transformations of antiviral drug “Triazaverin” and its analogues‑2-alkylthio‑6-nitro‑1,2,4-triazolo[5,1-c][1,2,4]triazine‑7-ones 1a-d examined the oxidation of alkylthio groups to the corresponding sulfoxides 2a-d and sulfones 3a-d, as well as the process of nucleophilic substitution sulfonyloxy group of cysteine and cysteamine with the formation of compounds 5 and 6.

Triazolo[5,1-b]purines are rare structural analogues of natural nucleosides and nucleobases purine series. At the same time, prominent representatives of azolopurines exhibit a broad spectrum of antiviral effect, activity against of rheumatoid arthritis, psoriasis, Alzheimer's, Parkinson's and etc. Despite the practical value azolo[5,1-b]purines extremely sparingly represented in the chemical literature, due to the complexity of their synthesis. We suggest a convenient way to synthesize triazolopurines with aminotriazolo[1,5-a]pyrimidines (2) as available starting compounds obtained in good yield by reduction of nitro derivatives (1).

New analogues of acyclovir have been prepared by reacting 1,2,4-triazolo[1,5-a]pyrimidin-7-ones 1а-i and (2-acetoxyethoxy)methyl acetate 2 in the presence of trimethylsilyl trifluoromethanesulfonate as a catalyst. Thei nteraction between the compounds 1а-е and 2 has led to a mixture of N3 and N4 isomers. In contrast, the reaction of compounds 1g-i and 2 proceeded selectively to form N3 isomers. In the case of compounds 1a-c the predominant product is the one with the acyclic moiety in azine ring (N4 isomer). Interaction between 1d-f and 2 has led to mixtures comprising mainly N3 isomer. It has been found that the ratio of glycosylation products 1 and 2 are thermodynamically controlled. The structure of the obtained compounds has been proved by 1Н, 13С, two-dimensional 1Н-13С NMR spectroscopy and X-ray analysis.