A protecting group-free approach to C-glycosides using the Ramberg–Bäcklund reaction

The one-pot conversion of unprotected monosaccharides directly into benzylsulfonylmethylene C-glycosides via a Horner–Wadsworth–Emmons/ring closure process is reported. Similar reactions giving sulfone-linked disaccharides are also discussed. One-pot transformations of unprotected monosaccharides to give styrenyl C-glycosides, by a tandem Horner–Wadsworth–Emmons/ring closure–halogenation/Ramberg–Bäcklund sequence, is then described.