Exploiting the chemistry of strained rings: synthesis of indoles via domino reaction of aryl iodides with 2H-azirines.

The highly strained 2H-azirine ring system has been the source of considerable theoretical and synthetic work. The reaction of these strained heterocycles with transition metals has been documented to give rise to ring opening and subsequent formation of varied heterocycles. An interesting domino reaction is described wherein the strained bicyclic alkene, norbornene, mediates the reaction of 2H-azirines with aryl iodides under palladium catalysis to provide indole or polycyclic dihydroimidazole heterocycles.