Selective, Zirconium-Mediated Cross-Coupling of Alkynes: Synthesis of Isomerically Pure 1,3-Dienes and 1,4-Diiodo 1,3-Dienes

Article abstract of DOI:10.1021/ja00190a021

The coupling reaction of zirconocene alkyne complexes with a second alkyne provides a general method for the preparation of asymmetrically substituted zirconacyclopentadienes.The overall transformation is the chemoselective and regioselective intermolecular cross-coupling of two alkynes, a goal that has not been achieved with other methodology.Isomerically pure 1,3-dienes or 1,4-diiodo 1,3-dienes are obtained upon treatment of the metallacyclopentadienes with aqueous acid or iodine.Because this synthesis can be carried out as a one-pot procedure starting from the alkynes and Schwartz's reagent (Cp₂ZrHCl), it is an attractive alternative to other transition-metal-based methods for the synthesis of dienes from vinyl halides and isolated vinylmetal starting materials.