Glycosylation Enabled by Successive Rhodium(II) and Brønsted Acid Catalysis.

Herein, we reported on a highly efficient glycosylation reaction comprising two chronological meticulously designed catalytic cycles: (1) rhodium-catalyzed formation of sulfonium ylide and (2) Brønsted acid-catalyzed formation of sulfonium ion. This protocol highlighted an effective and robust tactic to prepare a glycosyl sulfonium ion from a glycosyl sulfonium ylide precursor amenable for glycosylation.