SYNTHESIS AND BROMINATION OF BIS-HETERYL DITELLURIDES

It is known from the literature, that organic tellurium compounds have valuable biological properties. One example of such type of compounds is organic ditellurides. There are also known the usage of ditellurides as initiators in the synthesis of polymers, and they are widely used as synthons for the synthesis of another organotellurium compounds. In particular, the halogenation of diarylditellurides leads to the formation of such electrophilic reagents as aryltellurium trihalides, which proved to be suitable substrates for the synthesis of heterocyclic compounds. This paper describes a method for the synthesis of ditellurides, which contain condensed heterocycles of the quinazoline and thienopyrimidine series, by reducing of the corresponding heteryltellurium trichlorides. The interaction of 2-methyl-2-(trichlorotelluromethyl)-2,3-dihydro-5 H -thiazolo[2,3- b ]quinazolin-5-one hydrochloride with a 4-fold excess of 9-aqueous sodium sulfide in water at room temperature leads to formation of 2,2'-(ditellanidylbis(methylene))bis(2-methyl-2,3-dihydro-5 H -thiazolo[2,3- b ]quinazolin-5-one) with high yield. The introduction of the trifluoromethyl group at the 8 th position of 2-methyl-2-(trichlorotelluromethyl)-2,3-dihydro-5 H -thiazolo[2,3- b ]quinazolin-5-one hydrochloride increases the yield of the target ditelluride. 2-[(Trichlorotelluro)methyl]-2,3,6,7,8,9-hexahydro-5 H -benzo[4,5]thieno[2,3- d ]thiazolo[3,2- a ]pyrimidin-5-one hydrochloride was used for the  study of  the impact of the condensed with pyrimidine moiety cycle on the formation of ditellurides in the sodium sulfide reduction reaction and  it was stated  that under the found conditions it is uniformly converted into 2,2'-(ditellanidylbis(methylene))bis(2,3,6,7,8,9)-hexahydro-5 H -benzo[4,5]thieno[2,3- d ]thiazolo­[3,2- a ]-pyrimidin-5-one). The obtained ditellurides were used in the bromination reaction. It was found that the interaction of the starting ditellurides with a triple excess of bromine in chloroform medium allows obtaining the tribromides of the thiazoloquinazoline and thiazolothienopyrimidine series selectively. Therefore, the hydrochlorides of trichlorotelluromethyl-substituted thiazolinopyrimidines can be reduced to bis heterylditellurides, which under bromination conditions form tribromotelluromethyl-substituted thiazolinopyrimidines.