Синтез и электрофильная гетероциклизация 3 алкенилсульфанил-5-фенил-1,2,4-триазинов под дейст-вием иода и брома

Abstract

Derivatives of 1,2,4-triazine-3-thione are interesting research objects due to a wide range of their applications: drugs, optical substances, precursors for synthesis of new pyridine systems by the Diels-Alder reaction. In the present study, using alkylation of 5-phenyl-2,3-dihydro-1,2,4-triazine-3-thione (1) by 3-chloro-2-methyl-propene, 2,3-dibromopropene-1, 1-bromo-3-methylbut-2-ene and 4-brombut-1-ene, we have obtained 3-(2-methylprop-1-enyl)-, 3-(2-bromoprop-1-enyl)-, 3-prenylsulfanyl- and 3-butenylsulfanyl-5-phenyl-1,2,4-triazines (2a-d), previously unknown. In the 1H NMR spectrum of compound 2b, the shifts of the signal of pro-tons of the SCH2 group and the signal of protons of the vinyl group into a weak field by 0.48 ppm and 0.60 ppm can be observed, compared to the similar signals in the spectrum of 3-allylsulfanyl-5-phenyl-1,2,4-triazine. This may be due to the bromine atom in the allyl fragment. The weakest-field signal in the 13C NMR spectra of compounds 2a-d in the region of 171.86–173.68 ppm refers to the aromatic carbon atom of the triazine cycle in the third position (C-3), bound to a sulfur atom and two nitrogen atoms. New condensed heterocyclic systems of ionic type with a bridging nitrogen atom have been synthesized by electrophilic heterocyclization of methallyl-, bromallyl-, prenyl- and butenyl sulfides 2a-d. At the same time, [1,3]thiazolo[3,2-b][1,2,4]triazinium halides have been obtained by heterocyclization of compounds 2a,2b, and [1,3]thiazino[3,2–b][1,2,4]triazinium halides have been produced by heterocyclization of com-pounds 2c,2d. In the 1H NMR spectra of triazinium halides, a characteristic shift of the signal of the H-6 aromatic proton to the weak field region is observed in comparison with the similar sig-nal in the spectrum of the initial 2a-d sulfides. In the 13C NMR spectra of triazinium halides, there is a shift in the signal of the aromatic carbon atom associated with a sulfur atom and two nitrogen atoms (in the region of 162.56-172.42 ppm), which can be explained by the appearance of a positively charged nitrogen atom in their structure.