Indoles Rather than Triazoles from the Ruthenium Porphyrin-Catalyzed Reaction of Alkynes with Aryl Azides

An unprecedented reactivity of aryl azides toward alkynes is presented herein. The reaction performed well in the presence of 2 mol % of ruthenium porphyrin catalysts and afforded substituted indoles instead of triazoles. The procedure is particularly appealing for the synthesis of C3-functionalized indoles which bear EWG on the fragment coming from the azide. The method allowed the synthesis of 15 derivatives with yields up to 95%, high regioselectivity, and without requiring the time-consuming prefunctionalization of reagents and the addition of oxidants and/or additives.