Complexes of Tellurium Tetrahalides With 3-Allyl-2-(2-Methylthio)quinazolin-4(3h)-One

Regioselectivity in organic chemistry is a crucial concept for the synthesis of organic heterocyclic compounds. This concept determines the direction of a reaction towards the formation of a specific product from a possible set of structures. In this context, the regioselectivity of electrophilic heterocyclization depends on the nature of the electrophilic reagent, the structure of the substrate, and the polarity of the solvent. Special attention is given to substrates with two unsaturated fragments. Literature data have shown that the reaction depends on the type of electrophilic reagent; for example, iodination leads to the annulation of a six-membered dihydrothiazine, while bromination results in the annulation of a thiazolinone ring. In this study, the interaction of tellurium tetrahalides with 3-allyl-2-(2-methylthio)quinazolin-4(3H)-one, which has various alkene substituents, was investigated. Prior to the study, the initial metallothioether was synthesized for the first time. In the reaction of tellurium tetrahalides with 3-allyl-2-(2-methylthio)quinazolin-4(3H)-one, molecular adducts of thioether-tellurium tetrahalide with a 1:1 ratio were obtained. The experimental results demonstrate that an excess of the halogenating reagent and changes in reaction conditions do not affect the reaction product. Thus, this work highlights the importance of studying the regioselectivity of electrophilic intramolecular heterocyclization reactions and the potential use of tellurium tetrahalides for obtaining molecular complexes.