Iron-Catalyzed Radical Cycloaddition of 2H-Azirines and Enamides for the Synthesis of Pyrroles.

A novel and efficient Fe-catalyzed radical cycloaddition of 2H-azirines and enamides for the synthesis of substituted pyrroles has been developed. The radical cycloaddition reaction proceeded through a conceptually new Fe(II)-catalyzed homolytic cleavage of C-N bond of 2H-azirines sequential radical cyclization with enamides. The reaction used readily available starting materials, tolerated various functional groups, and afforded valuable triaryl-substituted pyrroles in good to high yields under mild reaction conditions.