Stereoselective Synthesis of Cyclic Ethers by Intramolecular Trapping of Dicobalt Hexacarbonyl-Stabilized Propargylic Cations

The intramolecular attack of a hydroxy group on an exo-biscobalthexacarbonyl propargylic cation provides cyclic ethers with six- to nine-membered rings. The scope and limitations of the methodology are described. The reaction is stereoselective when additional stereocenters are present, providing iterative methodology to access ladder-like cyclic ethers.