Synthesis of chiral azides from C-2 substituted glycals and their transformation to C3-glycoconjugates and α-triazolo-naphthalene polyol.

A Lewis-acid-mediated highly regio- and stereoselective chiral azidation of C2-substituted glycals is reported. This strategy provides excellent, scalable, and mild reaction conditions for the stereoselective introduction of the azido group at the C3-position of various C2-substituted glycals. The reactivity of the various glycals reveals that the electron-withdrawing behavior of the C2-group is crucial for C3-selectivity. The newly installed azido group was used as a handle for the synthesis of various C3-glycoconjugates and α-chiral azido naphthalene polyols.