Chiral Copper(II) Complex‐Catalyzes Site‐Selective Monofunctionalization of Levoglucosan Analogs

In this work, we report the development of a chiral copper‐catalyzed, site‐selective monofunctionalization of levoglucosan and analogs. This strategy employs CuCl 2 in combination with a BOX ligand to achieve regioselective functionalization at the O2 or O4 positions. The method proved effective with a range of electrophiles, exhibiting optimal performance for the regioselective installation of benzyl and tosyl groups. The protocol was also successfully applied to an aminosugar analog. However, in the case of an iminosugar analog, functionalization mediated by a zinc diamine complex afforded superior results. Moreover, an unprecedented reaction sequence enabled the selective synthesis of complex azidosugars, including the rapid preparation of the key intermediate 3‐azidogalactose. Overall, this approach represents a rare and valuable example of copper catalysis applied to the selective functionalization of carbohydrates.