Synthesis of 2‑Aminopyrroles Via Metal-Free Annulation of Ynamides with 2H‑Azirines

A novel metal-free annulation of ynamides with 2H-azirines catalyzed by BF3·Et2O is described, leading to the construction of polysubstituted 2-aminopyrroles in a facile, flexible, and atom-economical way. This synthetic strategy proceeds with efficiency, broad substrate scope, and short reaction time under mild reaction conditions. Furthermore, the obtained annulation products could be modified to generate diverse 2-iminopyrrole frameworks in high yields.