The Ramberg–Bäcklund reaction for the synthesis of C-glycosides, C-linked-disaccharides and related compounds

The discovery of the Ramberg–Bäcklund procedure for preparing exo-glycals from S-glycoside dioxides, developed independently in (Old) York and New York, is reviewed. The methodology is successful with glucose, galactose, mannose, xylose, fucose, ribose, altrose, 2-deoxy-arabino-hexose (2-deoxy-glucose) and daunosamine derivatives, and has been used to prepare di-, tri- and tetra-substituted exo-glycals. More recent developments, such as one-pot variants, and protecting group-free procedures, are also covered. Synthetic applications of the exo-glycals, for example, to prepare β-glycosidase inhibitors, spirocyclic glucose derivatives, β-C-glycosides, C-glycosyl porphyrin glycoconjugates and C-glycosyl amino acids, are also discussed. Finally, applications of the Ramberg–Bäcklund process for the synthesis of known and novel C-glycosides, and in natural product synthesis, are reviewed.