Iron-Catalyzed Sustainable Synthesis of Pyrrole

Efficient, sustainable, highly regiospecific substituted pyrroles were synthesized using a well-defined, air stable, molecular iron(0) complex. The developed methodology is broadly applicable and tolerates a variety of functional groups. C-2, C-3, and C-2 & C-4 substituted pyrroles were synthesized in good yield. Symmetrical bis-pyrroles were accessible for the first time using an iron catalyst. On the basis of the experimental observation, we propose that the reaction proceeds through a hydrogen autotransfer process followed by second oxidation/intramolecular dehydrative condensation to provide the pyrrole.