One-Step TEMPO-Catalyzed and Water-Mediated Stereoselective Conversion of Glycals into 2‑Azido-2-deoxysugars with a PIFA–Trimethylsilyl Azide Reagent System

An unprecedented water-mediated and TEMPO-catalyzed, one-step, highly regiospecific and stereoselective functionalization of glycals to 2-azido-2-deoxysugars has been developed using a PIFA–Me₃SiN₃ reagent system in the presence of Bu₄NHSO₄ as a phase-transfer catalyst. The method is metal-free, proceeds under mild reaction conditions, and tolerates a variety of protecting groups. Using this method, the synthesis of an important trisaccharide unit bound by the monoclonal anti-I Ma antibody has also been demonstrated.