Taming Unhindered Alkyl Azides by Intramolecular Hydrogen-Azide Interaction for Discriminative Conjugation onto Alkyl Diazides

We report herein the unique reactivities of α-azido secondary acetamides (α-AzSAs) as minimal and unhindered azide structures. The NH–azide interaction in the α-AzSAs, supposed by DFT calculation, allowed selective conjugation in the presence of other azido moieties. With Staudinger-Bertozzi ligation, α-AzSAs proceeded the conjugation prior to the other primary alkyl azides. On the other hand, in propargyl cation-mediated triazole synthesis, other alkyl azides, including tertiary alkyl azides, underwent the conjugation faster than α-AzSAs. We also demonstrated discriminative integration of the functional components onto the diazide modular hubs.