Aminooxygenation of Ynamides with <i>N-</i>Hydroxybenzotriazoles: Synthesis of α‑Benzotriazolyl Carbonyl Compounds

Addition of N-hydroxybenzotriazoles to ynamides causes spontaneous rearrangement, resulting in α-benzotriazolyl imides. The transformation proceeded at rt in the absence of any catalyst but could be efficiently catalyzed by Zn­(OTf)2. Crossover experiments confirmed that the rearrangement is an intramolecular process, most likely via a concerted mechanism. However, heating the mixture above 110 °C resulted in isomerization of N2 into N1 product, via heterolytic C–N bond dissociation. This tandem addition–rearrangement sequence provides an efficient and atom-economical synthetic route for the synthesis of α-benzotriazolyl carbonyl compounds.