Coping with substituent effects in divinylcyclopropyl diazene rearrangements

Surprising differences between the chemistry of ester and ketone derivatives of C-7-substituted divinylcyclopropyl [2.2.1]diazenes was discovered. While the ester does not, the ketone undergoes facile Cope rearrangement. These topics, the chemistry of the product, and mechanistic implications are discussed.