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.
Indoles rather than triazoles from the ruthenium porphyrin-catalyzed reaction of alkynes with aryl azides / Zardi, P.; Savoldelli, A.; Carminati, D. M.; Caselli, A.; Ragaini, F.; Gallo, E.. - In: ACS CATALYSIS. - ISSN 2155-5435. - 4:11(2014), pp. 3820-3823. [10.1021/cs5012712]