Synthesis of ketofuranosides by epoxidation-ring closure of enol ethers

Z- and E-Hydroxy enol ethers, obtained from aldoses, either by an elimination reaction followed by a reduction or by a Wittig-Horner reaction, have been epoxidized using m-chloroperbenzoic acid or the Sharpless' procedure to afford ketofuranosides. The stereochemistry of both the epoxidation and the subsequent cyclization are discussed.