![53. Chemoselective Sequential Click Ligations Directed by Enhanced Reactivity of an Aromatic Ynamine](https://cdn.prod.website-files.com/6380be6ed1140b78394d35e6/6481e15b5b771472f492bda5_images_medium_ol-2016-006358_0005.gif)
Aromatic ynamines or N-alkynylheteroarenes are highly reactive alkyne components in Cu-catalyzed Huisgen [3 + 2] cycloaddition (“click”) reactions. This enhanced reactivity enables the chemoselective formation of 1,4-triazoles using the representative aromatic ynamine N-ethynylbenzimidazole in the presence of a competing aliphatic alkyne substrate. The unique chemoselectivity profile of N-ethynylbenzimidazole is further demonstrated by the sequential click ligation of a series of highly functionalized azides using a heterobifunctional diyne, dispelling the need for alkyne protecting groups.