Glycosyl bromides of ulopyranosonic acid derivatives, both with furanoid and pyranoid ring structures (e.g., 2), are widely used for the preparation of glycosylidene-spiro-heterocycles of biological interest, such as the naturally occurring herbicide (+)-hydantocidin, a ribofuranosylidene-spiro-hydantoin, or the lowmicromolar glycogen phosphorylase inhibitors glucopyranosylidene-spiro-(thio)hydantoins (for other spirocycles prepared from analogous glycosyl bromides, see References 3–7). These compounds also serve as starting materials toward anomeric α-amino acid derivatives, as well as 1-C-substituted glycals.
