The thermal [3,3] rearrangement of 3,3-di-cyano-1,5-enynes to γ-allenyl alkylidenemalononitriles (the “enyne Cope rearrangement”) has largely eluded synthetic value as the desired products, too, are thermally reactive and ultimately yield 6π electrocyclization products. Herein, we describe experimental and computation studies related to the thermal rearrangement of 1,5-enynes, structural features to halt the thermal rearrangement at the allene-stage, and a reductive variant for preparing bifunctional allenyl malononitriles. We also describe various ways that the bifunctional building blocks can be manipulated and converted to cyclic and acyclic architectures.

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.

Explored was the competitive ring-closing metathesis vs. ring-rearrangement metathesis of bicyclo[3.2.1]octenes prepared by a simple and convergent synthesis from bicyclic alkylidenemalono-nitriles and allylic electrophiles. It was uncovered that ring-closing metathesis...