Rhenium(V)‐Catalyzed Synthesis of 2‐Deoxy‐α‐glycosides.

A mild method for the synthesis of 2-deoxysugars from the coupling of glycals with a range of nucleophiles is described. The method employs 1 mol % of an air- and moisture-tolerant rhenium−oxo complex [ReOCl<sub>3</sub>(SMe<sub>2</sub>)(Ph<sub>3</sub>PO)] as a catalyst for the formation of <i>O</i>-,<i> N</i>-, and <i>S</i>-<i>α</i>-glycosides. The catalytic system tolerates a number of commonly employed protecting groups, including isopropylidene acetals, alkyl and silyl ethers, acetates, and benzoates. Furthermore, the high-oxidation-state complex selectively catalyzes the coupling with the glycal acceptor in preference to oxidation of the glycals, alcohols, and even thiols.