Iodine-Catalyzed Thioglycosylation of Indole and Tryptophan-Containing Peptides with Thioglycosides

An efficient iodine-catalyzed thioglycosylation reaction for the synthesis of indole thioglycosides and <i>S</i>-glycosylated peptides is reported. This method employs molecular iodine as a metal-free catalyst and thioglycosides as sulfur donors, achieving high yields (up to 97%) under mild conditions. The reaction is compatible with a broad range of substrates, including various monosaccharide-derived thioglycosides and indoles with different substituents. Additionally, the method is successfully applied to the functionalization of tryptophan-containing peptides, yielding thioglycopeptide derivatives in moderate to good yields. The study not only expands the synthetic accessibility to S-linked glycopeptides but also provides a valuable approach for peptide functionalization in glycochemistry.