One-Step Derivatization of Reducing Oligosaccharides for Rapid and Live-Cell-Compatible Chelation-Assisted CuAAC Conjugation.

We report a new reagent for the functionalization of unprotected oligosaccharides with a picolyl azide group at the anomeric position for chelation-assisted copper-catalyzed alkyne-azide cycloaddition (CuAAC) glycoconjugation. We show that oligosaccharides functionalized with this moiety react with an apparent second-order rate constant of 193 m(-1)  s(-1) and can be used to functionalize biomolecules bearing alkyne moieties introduced through metabolic labeling, including in live cells.