By addition of tellurium tetrahalides and aryltellurium trihalides to acetylenes

1 By addition of tellurium tetrahalides and aryltellurium trihalides to acetylenes 

Tellurium tetrachloride and aryltellurium trichloride, as well as tellurium tetrabro-mide and aryltellurium tribromides add to acetylenes to produce, respectively, 2-halovinyl tellurium trihalides and dihalides, which can be submitted to further manipulations. 

The addition of TeCl4, aryltellurium trichlorides and TeBr4 is stereoselective giving only Z addncts. 

The addition of aryltellurium tribromides exhibits Z or configuration depending on the solvent, benzene or ethanol used in the reaction. 

In the case of 3-hydroxyalkynes the OH group promotes anti addition. Depending on the steric hindrance at the propargylic position, four- or five-membered cyclic tellurium oxychlorides are formed.  

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