We report the first highly selective kinetic resolution of racemic α-chiral azides by Cu-catalyzed azide-alkyne cycloadditions (CuAAC), providing facile access to chiral α-tertiary azides and 1,2,3-triazoles with newly developed PYBOX ligands with a C4 sulfonyl group. The key role of the C4 sulfonyl in tuning the electronic and steric properties of the chiral catalysts to enhance enantiomer discrimination