A Metal-Free Approach to Imidazo[2,1- a ]isoquinolines from 2 H -Azirines as 2-Atom Synthons and Isoquinolinium N -Ylides

Currently, the protocol to achieve imidazo[2,1-a]isoquinolines from isoquinolinium N-ylides was rare. Herein, a novel metal-free approach to imidazo[2,1-a]isoquinolines from 2H-azirines and isoquinolinium N-ylides has been successfully developed in a one-pot way, in which 2H-azirines acted as 2-atom synthons to construct azaheterocycles. The investigation indicated that the protocol to synthesize imidazo[2,1-a]isoquinolines might proceed via a radical pathway, and this reaction underwent a cascade of formal [3 + 2] annulation, ring-opening, and elimination/aromatization processes.