Bicyclic nucleoside analogues from d-glucose: synthesis of chiral as well as racemic 1,4-dioxepane ring-fused derivatives Original Research Article

The dioxepanofuranose derivatives 4 and 12, obtained through the cyclization of the 3-(2-hydroxyethyl) ether of a d-xylo-pentodialdose derivative, were appropriately functionalized and elaborated to the first examples of the new class of 3′-O and 5′-O-bicyclic nucleoside analogues 9, 10, and 14 with a fused seven-membered ring. Reactions carried out through the intermediacy of the d-xylo-pentodialdose derivative 5 yielded racemic products, while prior protection of the 4-formyl group (as in 7) before deprotection of the 1,2-hydroxyl groups led to optically active analogues.