ВПЛИВ ГАЛОГЕНУ В АРИЛТЕЛУРТРИГАЛОГЕНІДІ НА РЕАКЦІЮЕЛЕКТРОФІЛЬНОЇ ЦИКЛІЗАЦІЇ N-АЛКЕНІЛЬНИХ ПОХІДНИХ 2-ТІОКСОБЕНЗО (ТІЄНО) ПІРИМІДИН-4-ОНІВ

Abstract

It is known from the literature that electrophilic heterocyclization of unsaturated substrates under the action of aryltellurium trichlorides is w idely used to obtain tellurium-containing polycondensed heterocyclic systems, whereas the use of p -alkoxyphenyltellurium tribromides in such reactions is almost not described. p -Ethoxyphenyltelluriumtribromide was used for study the influence of a halogen in the electrophilic aryltelluronium reagent on products' yields and on the direction of the electrophilic intramolecular cyclization of N-alkenyl-2-thioxoben zo(thieno)pyrimidine-4-ones. It was not possible to obtain this electrophile wit h the reaction of tellurium tetrabromide with benzene containing electron donating group, so it w as synthesized by bromination of the corresponding ditelluride in chloroform medium. The interaction between tellurium-containing electrophile and N-alkenyl-2-thioxobenzo(thieno)pyr imidine-4-ones was carried out in glacial acetic acid at room temperature. It has been established t hat during aryltellurobromination of 3-allyl- quinazoline-2-thione and N-alkenyl thioxo-thieno-py rimidinones, the annelation of the thiazoline ring takes place, with the formation of a linear condens ed system with an exocyclic aryltellurium fragment – hydrobromides of 3-[dibromo(4-ethoxyphenyl)tellur omethyl]-2,3-dihydro-5 H -[1,3]thiazolo[2,3- b]quinazolin-5-one, 2-(dibromo(4-ethoxyphenyl)-tell uromethyl)-2,3,6,7,8,9-hexahydro-5 H - benzo[4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimidi n-5-one and 2-methyl-2-(dibromo(4- ethoxyphenyl)-2,3,6,7,8,9-hexahydro-5 H -benzo[4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimid ine-5- one. The structure of the products of bromotelluro- cyclization is similar to the structure of products of aryltellurochlorination of the corresponding hetero cycles. However, the yields of salts with the exocyclic bromoaryltellurium fragment are smaller c ompared to chloro- analogs. Lower yields of hydrobromides are associated with lower stability o f intermediate bromotelluronium cation compared with chlorotelluronium, which is confirmed by theor etical calculations of Gibbs free energy of interaction of aryldihalidetellanium cation with an unsaturated substrate. Computations were performed using DFT level of theory in PRIRODA 17 p rogram with using of GGA PBE functional and 3 ζ basis set. The effect of solvent medium (acetic ac id) was taken into account using the COSMO model with PM7 Hamiltonian in MOPAC2016 program. Th e composition and structure of all obtained compounds are proved by elemental analysis and NMR spectra.