Synthesis of N-unsubstituted 1,2,3-triazoles via a cascade including propargyl azides, allenyl azides, and triazafulvenes

Abstract

About thirty NH-1,2,3-triazoles with at least one additional functional group in a side chain at C-4 were prepared from propargyl substrates. These reactions included propargyl azides and their [3,3]-sigmatropic rearrangement to generate short-lived allenyl azides, which cyclized to form triazafulvenes that could be trapped by addition of N- or O-nucleophiles. In most cases, simple substrates and cheap sodium azide were utilized as starting compounds, and the syntheses were performed by using a one-pot procedure without isolation of any dangerous azides. This method to prepare NH-1,2,3-triazoles turned out to be compatible with quite different substitution patterns of the propargyl substrate.