ELECTROPHILE CYCLIZATION OF N (S, Se)-ALKENYL DERIVATIVES OF PYRIMIDINONE WITH p-METOXYPHENYLTELLURIUM TRICHLORIDE

Abstract

Pyrimidinone is a component of bioactive natural compounds such as uracil, thymine and cytosine. Pyrimidinone derivatives exhibit antitumor, antiviral and psychotropic properties. The heterocyclization of unsaturated pyrimidinetione derivatives produces condensed azolopyrimidines, which also exhibit a wide range of biological activity. The introduction а tellurium atom into such systems can increase their bioactivity. One of the most convenient and straightforward methods for introducing a tellurium atom is the electrophilic intramolecular cyclization method.The interaction between synthesized for the first time 3-methyl-2-thioxopyrimidin-4-one and p-methoxyphenyltellurium trichloride was carried out in glacial acetic acid at room temperature. It has been established that the electrophilic intramolecular cyclization of N-methallyl 2-thioxopyrimidine-4-one p-methoxyphenyltellurium trichloride takes place with the participation of a sulfur atom with the anelation of the thiazoline cycle to the pyrimidine system. As a result of reaction received 2,7-Dimethyl-2-{[dichloro(4-methoxyphenyl)-telluro]methyl}-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-5-one hydrochloride.The regioselectivity of the process of electrophilic cyclization with aryltelluriumtrichlotide was investigated on 2-S-alkenyl derivatives of 6-methylpyrimidin-4-one. It is shown that the reaction between aryltellurium trichloride and 2-thioalkenyl derivatives of 6-methylpyrimidin-4-one results in the formation of cyclization products with the involvement of a nitrogen atom at the third position of the pyrimidine. It is revealed that tellurofunctionalized thiazolinopyrimidines are formed in the form of complexes with aryltellurium trichloride. To study the effect of chalcogen on the regioselectivity of the process of electrophilic cyclization in reaction with p-methoxyphenyltellurium trichloride, a metalyl selenoether of 6-methylpyrimidin-4-one was used. It has been proved that 2-Se-methallyl N-1,3-unsubstituted pyrimidinone is cyclized by aryltellur trichloride to form a selenazolinopyrimidine system, which in turn allows to obtain potentially biologically active heterocycles with an endocyclic Selenium atom and an exocyclic Tellurium atom. The nature of chalcogen does not affect the direction of electrophilic intramolecular cyclization. The structure of obtained compounds were proved by NMR spectroscopy, IR spectroscopy and elemental analysis.