Chemoselective Glycosylation of Peptides via S‐Alkylation Reaction

An efficient and fast procedure in execution for synthesizing S‐linked glycopeptides is reported. It uses activated molecular sieves as a base to promote the selective S‐alkylation of readily prepared cysteine‐containing peptides, upon reaction of appropriate glycosyl halides. Due to the very mild conditions employed, the chemoselective linkage of the electrophilic sugar with a peptide sulfhydryl group occurred in a satisfactory yield, allowing the incorporation of mono and disaccharide moieties. The sugar‐peptide conjugates obtained from α‐D‐glycosyl derivatives adopt a beta‐S‐conformation, indicating the high stereoselectivity of the substitution reaction