Utility of Unsaturated Terminal Epoxides in Cyclopropane Synthesis

Developments in the synthesis of bicyclo[n.1.0]alkanes by lithium 2,2,6,6-tetramethylpiperidide-induced intramolecular cyclopropanation of unsaturated terminal epoxides are reviewed. The main alternative intramolecular cyclopropanation strategies are also briefly discussed to put the epoxide chemistry in perspective. Terminal epoxide (or chlorohydrin) precursors possessing a tethered alkene undergo intramolecular cyclopropanation with complete stereoselectivity and in generally good to excellent yields to give cyclopropyl alcohols; application of this cyclopropanation methodology in the synthesis of natural products is also reviewed.