A Michael Alternative to Cyclopentene Annulations

Abstract

Intramolecular cyclopentene annulations involving carbenoidmediated cyclopropanations (Eq. 1), followed by the nucleophilic ring opening of vinylcyclopropanes have been studied extensively² and have been applied successfully to the synthesis of triquinane terpenes.³ More recently, intermolecular [2 + 3] annulations of enones (Eq. 2), have also been studied⁴ and applied in the synthesis of these terpenes.⁵