Aminooxygenation of Ynamides with N-Hydroxybenzotriazoles: Synthesis of α-Benzotriazolyl Carbonyl Compounds

Abstract

Addition of N-hydroxybenzotriazoles to ynamides occurred with spontaneous rearrangement into 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 oC 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 towards α-benzotriazolyl carbonyl compounds.