An Enyne Cope Rearrangement Enables Polycycloalkane Synthesis from Readily Available Starting Materials.

Cyclohexanone-derived Knoevenagel adducts (cyclohexylidenemalononitriles) and two different propargyl electrophiles serve as carbon sources for assembling diverse 6/7/5 tricycloalkanes, a common terpenoid framework. The sequence involves three unique reactions: 1) deconjugative propargylation, 2) one-pot enyne Cope rearrangement/deconjugative propargylation, and 3) an allenic Pauson-Khand reaction.