1,1-Dibromoalk-1-enes were dimerized readily in the presence
of copper iodide, a diamine ligand, and cesium carbonate in DMF
to give symmetrical 1,3-diynes. The reaction was found to be selective
and rather general, furnishing the corresponding diynes in good
yields, even with complex and sensitive dibromides, and provides
useful insights into the reactivity of 1,1-dibromoalk-1-enes with
copper(I).
dibromoalkenes - copper catalysis - 1,3-diynes