o-(p-Methoxyphenylethynyl)phenyl Glycosides: Versatile New Glycosylation Donors for the Highly Efficient Construction of Glycosidic Linkages

• DOI: 10.1021/jacs.7b07020
• Publication Date: 2017-08-24T04:09:05Z
• Authors: Yang Hu; Ke Yu; Li-Li Shi; Lei Liu; Jing-Jing Sui; De-Yong Liu; Bin Xiong; Jian-Song Sun
• Keywords: Glycosidic bond; Trisaccharide; Glycosyl donor; Glycoconjugate; Carbohydrate conformation

A novel alkyne-activation-based glycosylation protocol using o-(p-methoxyphenylethynyl)phenyl (MPEP) glycoside was established. The glycosyl MPEP donors were shelf-stable and could be prepared efficiently via Sonogashira reaction from the corresponding o-iodophenyl (IP) glycosides. outstanding stability of IP glycosides as well their efficient transformations to dramatically facilitates syntheses acceptors. Furthermore, they make applicable latent-active oligosaccharide glycoconjugate synthetic strategy, with latent form active form, illustrated by highly fabrication Streptococcus pneumoniae type 3 trisaccharide. phenolic nature bestows on new enhanced compared thioglycoside counterparts toward activation conditions applied for trichloroacetimidate (TCAI) o-alkynylbenzoate (ABz) donor. Thus, MPEPs can also utilized in selective one-pot exemplified oligosaccharides successive glycosylations TCAI, ABz, EPMP donors. Despite sharing identical promotion donors, odor-free starting material (IP), stable departure structure leaving group (3-iodobenzofuran), decreased nucleophilicity o-MPEP help eliminate three major shortcomings (unpleasant odor material, detrimental interference cleaved group, aglycon intra- or intermolecular migration) while maintaining prominent features methodology, including broad substrate scopes, mild conditions, versatile applications existing synthesis strategies. Based experimental results, a mechanism proposed, which supported systematic mechanistic investigations, trapping intermediates, design vital disarmed rhamnosyl donor, isolation characterization species group.