Enantiomerically Pure α,β-Unsaturated Five-Membered-Ring Aldehydes by Ring Contraction of Epoxyhexopyranosides

Article abstract of DOI:10.1021/jo970666k

A series of epoxyhexopyranosides, variously substituted in the 6-position, were each transformed by ring contraction into a single, enantiomerically pure, α,β-unsaturated furanosidic aldehyde. Similar ring contraction of a C-propylglycosidic analog of one of the epoxyhexopyranosides gave a mixture of two diastereomeric aldehydes. This finding supports the previously suggested mechanism of the reaction and indicates that O-glycosidic epoxypyranosides also rearrange into two aldehydes, one of which is unstable.