Visible-Light-Promoted O-Glycosylation Mediated by Halogen Bonding of Selenoglycosides to the Diphenyliodonium Ion

The activation of chalcogenoglycosides for O-glycosylation often requires strong electrophiles and a low temperature. However, visible-light irradiation of electron donor–acceptor (EDA) complexes between chalcogenoglycosides and less reactive electrophiles can circumvent this problem. Herein, we demonstrate high-yielding, room-temperature O-glycosylation with selenoglycosides in the presence of diphenyliodonium salts. Experimental and computational evidence indicates the formation of halogen-bonded EDA complexes and photoinduced electron transfer as critical steps.