Stereoselective synthesis of Z-2-bromo-2-phenylvinyltellurium tribromide and Z,Z-bis(2-bromo-2-phenylvinyl)ditelluride

Abstract

Reactions of alkynes with tellurium tetrachloride have been reported [1, 5–11]. However, there are a few published data on reactions of tellurium tetrabromide with acetylenes [12–14]. We have developed efficient procedures for the stereoselective synthesis of E,E-bis(2-bromovinyl)tellurium dibromide and E-(2-bromovinyl)tellurium tribromide by reaction of tellurium tetrabromide with acetylene [12, 13]. The addition of TeBr4 to phenylacetylene and hept-1-yne under reflux gives rise to bis-adducts, bis(2-bromo-2-phenylvinyl)tellurium dibromide and bis(2-bromohept-1-en-1-yl)tellurium dibromide in 89 and 70% yield, respectively, as mixtures of Z and E isomers with Z-isomers pre-vailing (in the case of phenylacetylene Z : E = 4.5 : 1) [14]. The data on stereoselective synthesis of monoadduct, 2bromo-2-phenylvinyltellurium tribromide, are absent.