The addition of copper reagents prepared by transmetalation from polyfunctional organozinc iodides to reactive alkynes such as 1-(methylthio)-1-hexyne, phenylacetylene and acetylene, leads to stereochemically well-defined (syn addition), highly functionalized alkenylcopper reagents that after protonation, allylation, iodolysis, or stannylation afford stereochemically pure di-, tri-, and tetrasubstituted olefins. A similar intramolecular carbocupration has allowed the preparation of highly substituted five-membered carbocycles. Compared to lithium-or magnesium-copper reagents, the highly functionalized copper reagents can contain an ester, nitrile, or chloride function. However, they display a lower reactivity than the lithium- or magnesium-copper reagents and do not react with unactivated terminal alkynes