Enantioselective synthesis of alpha,beta,alpha '-trisubstituted cyclic ethers'

A synthetic strategy for the preparation of trisusbstituted cyclic ethers i s presented, in which the stereochemistry at the carbon atoms adjacent to t he oxygen of the ether was controlled by means of a hetero Diels-Alder reac tion between a monoactivated diene and a chiral aldehyde. The adducts were transformed into linear ethers, which were then used for the preparation of cis and trans cyclic ethers of different sizes. A cis-oxepane, cis-oxonane , and cis-oxocane and a trans-oxocane were prepared as examples of the scop e of the strategy.