Preparation of Glycosyl Bromides of α-d-Gluco-hept-2-ulopyranosonic Acid Derivatives

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, ¹ a ribofuranosylidene-spiro-hydantoin, or the lowmicromolar glycogen phosphorylase inhibitors glucopyranosylidene-spiro-(thio)hydantoins ² (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, ^8–10 as well as 1-C-substituted glycals. ^11–14