Exocyclic vinyl ethers of ketofuranosides

Exocyclic vinyl ether derivatives of sugars are found in biosynthetic pathways and may serve as useful synthetic intermediates. The ketose subfamily of sugars is the least characterized in this field. Thus, the synthesis of exocyclic vinyl ether derivatives of ketohexoses via β-elimination was studied with respect to the nature of the 6-O leaving group and the protection of the 4-hydroxy group. We applied this study to protected l-sorbofuranoside and d-tagatofuranoside sugar derivatives in which the 4-hydroxy group and the 6-O-leaving group are in the syn configuration. Some reactions involving deprotection and reductive rearrangement of the tagatose-derived vinyl ether product were also studied.