Umpolung Reactivity in the Stereoselective Synthesis of S‐Linked 2‐Deoxyglycosides

Take control! An unprecedented sulfenylation of stereochemically defined 2-deoxyglycosyl lithium species with asymmetric sugar-derived disulfide acceptors enabled the stereoselective synthesis of both α- and β-S-linked 2-deoxyoligosaccharides. Reductive lithiation of 2-deoxyglycosyl phenylsulfides at −78 °C provides predominantly axial glycosyl lithium species, which upon warming isomerize to predominantly equatorial lithium species (see scheme).