Transition metal catalyzed (5 + 2) cycloadditions of vinylcyclopropanes and alkynes: a homolog of the Diels-Alder reaction for the synthesis of seven-membered rings

The seven-membered ring compounds are effectively synthesized by (5 + 2) cycloadditions of vinylcyclopropanes and alkynes, catalyzed by a transition metal, a homolog of the Diels-Alder reaction. The electronic and steric factors incorporated by the substituents of the alkyne do not influence the cycloaddition process, except for the influence on the volatile product.