Stereospecific chlorotelluration of terminal acetylenes

Synthesis of Novel E-2-Chlorovinyltellurium Compounds Based on the Stereospecific Anti-addition of Tellurium Tetrachloride to Acetylene

“…The methods are efficient, simple and based on readily available starting materials (acetylene and tellurium tetrachloride). In contrast to the syn- addition of tellurium tetrachloride to substituted acetylenes [9,10,11,12,13,14,15] the reaction of tellurium tetrachloride with acetylene proceeds in a stereospecific manner via anti -addition to give the products 1 and 2 of E -stereochemistry (Scheme 2 and Scheme 3). This are the first examples of anti -additions of tellurium tetrachloride to acetylenic hydrocarbons.…”

“…The reaction of TeCl 4 with phenylacetylene and diphenylacetylene afforded the corresponding 2-chlorovinyltellurium trichlorides, however, the stereochemistry of the products was not determined [9]. It has been shown later that the reactions of TeCl 4 with phenylacetylene, diphenylacetylene and alkylphenylacetylenes proceed in highly regiospecific and stereospecific manner via syn -addition to afford the products of Z -stereochemistry [10,11,12,13,14,15]. The Z -configuration was confirmed by X-ray analysis [15].…”

“…A mechanism with the formation of 4-membered transition state A was proposed in order to explain stereospecific syn -addition of tellurium tetrachloride to the triple bond of alkynes (Scheme 1) [14,20].…”

Hydrotelluration of acetylenic esters: structural characterization of stereoisomers of methyl/ethyl β-(aryltelluro)acrylates

“…12 125 Te chemical shis (unlike d 1 H values) and 1 H- 125 Te coupling constants have scarcely been used to characterize the stereoisomers in the product of a hydrotelluration reaction of an alkyne. Also, among the known b-substituted vinylorganyltellurides which are mostly liquids or low-melting solids, structural characterization of only a few of these in solid state is limited to either the (Z) [12][13][14][15] or (E) [16][17][18][19] isomers and to the best of our knowledge is not reported for both the stereoisomers of a given vinylorganyltelluride.…”

“…Keeping with our interest in the synthesis of functionalized organotelluriums and in continuation to our studies on chlorotelluration of 1-alkynes using bulky substituents on Te and the terminal acetylenes, 15 S). Our aim was twofold, (i) to examine how the reaction solvent and the nature of the aryl ligand bound to tellurium affect the stereospecicity of acetylenic ester hydrotelluration and (ii) study the stereochemistry of the products in the solid state.…”