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.