Dienamine-Induced Divinylcyclopropane-Cycloheptadiene Rearrangements

Sigmatropic rearrangements constitute an important group of pericyclic reactions. In contrast to cycloaddition reactions, examples of catalytic variants of electrocyclic reactions and sigmatropic rearrangements are still scarce in the chemical literature. Herein, we report the first organocatalytic Cope rearrangement of in situgenerated divinylcyclopropanes. The reactive motif is generated by condensation of 4-(2-vinylcyclopropyl)but-2-enal derivatives and a secondary amine catalyst to form a transient dienamine. The cycloheptadiene products can be obtained in high yield and excellent diastereoselectivity. Importantly, the reaction was demonstrated to be stereospecific, proceeds under mild conditions, and shows broad functional group tolerance.