Preparation of Seven-Membered-Ring Cyclic Ethers and 3-Alkylidenetetrahydropyrans from the Cyclization of Oxonium Cations Derived from Unsubstituted and Silicon-Containing 4-Alken-1-ols

Article abstract of DOI:10.1021/jo00285a016

Lewis acid promoted cyclization of mixed acetals derived from 4-alken-1-ols provides direct access to seven- or six-membered cyclic ethers.Ring size is determined primarily by the electronic bias of the alkene participant.Of particular significance are (a