We report the cycloisomerization of 1-alkenyl-1-alkynylcyclopropanes to cyclooctatriene products catalyzed by PtCl2/CO in hot xylene. In contrast to the reported enyne cycloisomerization, this 1,4-enyne cycloisomerization proceeds via an atypical addition of the allyl carbon to the alkyne in a 6-endo-dig cyclization.
