Visible Light Induced, Metal‐free Denitrative Formal [3+2] Cycloaddition for Trisubstituted‐Pyrrole Synthesis

A metal-free, regioselective synthesis of trisubstituted pyrroles has been developed through a formal [3+2] cycloaddition reaction between 2H-azirines and nitroalkenes under visible light/photoredox-catalyzed conditions. The reaction proceeds through 2H-azaallenyl radical addition on beta-nitrostyrenes in a Michael fashion followed by a base-mediated denitration reaction. The directive group influence of the nitro group controls the regiochemistry of the reaction.