Carbon–carbon bond formation by means of organotellurium compounds

Z vinylic tellurides are prepared by hydrotelluration of alkynes under nonreducing conditions using n-BuLi–Te–H2O as the hydrotellurating system. The same system promotes the hydrotelluration of alkenes containing electron withdrawing groups. Lithium and magnesium organotellurolates effect vinylic substitutions on vinylic halides, phosphates, sulphonates and acetates leading to the Z vinylic telluride exclusively. Tellurides are transmetallated with easily available organometallic reagents to give valuable synthetic building blocks (e.g. organolithiums and organocuprates). Reaction of vinylic tellurides with alkynes under Pd catalysis or with organocuprates gives the coupling products with retention of the double bond geometry.