Дослідження взаємодії арилтелуртрихлоридів з 2-S-алкенільними похідними хіназолону

Abstract

It is known that the quinazoline fragment is a structural element of many natural alkaloids. A promising method for the synthesis of condensed derivatives of quinazoline is the method of electrophilic intramolecular heterocyclization. The purpose of this work is to investigate the regioselectivity of electrophilic heterocyclization of S-allyl derivatives of quinazolone with aryltellurium trichlorides. N-(3)-phenyl-2-S-alkenyl derivatives of quinazolone with a non-terminal allyl substituent are used as substrates for aryltellurohalogenation. The choice of such objects is motivated by the presence of one additional nucleophilic center for cyclization – the endocyclic nitrogen atom in the first position of the pyrimidine cycle. Interaction of allyl(methallyl) substituted thioquinazolones with p methoxyphenyltellurium trichloride was carried out in acetic acid or tetrahydrofuran (THF) at room temperature for 8 hours stirring the reaction mixture. It has been established that irrespective of the ratio of reagents, the non-terminal alkenyl thioether, under the action of p-methoxyphenyltellurium trichloride, undergoes annulation of the thiazoline ring to form tricyclic condensed systems of the angular structure. It should be noted that the molecular complex of p-methoxyphenyltellurium trichloride with Sulfur atom of thiazolinoquinazolone is formed. The formation of such a complex was not observed under aryltellurohalogenation of N-alkenyl 2-thioxoquinazolones, where, obviously, there is intramolecular coordination of the Sulfur atom to the Tellurium atom. Instead, the use of the terminal-substituted dimethylallyl thioether in the reaction with p methoxyphenyltellurium trichloride in similar conditions changes the direction of the reaction and leads to the formation of the molecular complex. The impossibility of the cyclization is due to the steric shielding of the reaction center with respect to the tellurim-containing electrophile. Thus, thioethers of quinazolone with a terminal non-substituted allyl substituent under the action of p-methoxyphenyltellurium trichloride undergo cyclization, while the introduction of two methyl groups to the terminal carbon atom of the allyl fragment changes the direction of the reaction and leads to the formation of the molecular complex. Keywords: еlectrophilic cyclization; p-methoxyphenyltellurium trichloride; regiochemistry; thioxoquinazolone; thiazolinoquinazolone.