Iron(III) Porphyrin Catalyzed Cyclization of Ketones with Dimethyl Sulfoxide and Ammonium Acetate: One-Pot Synthesis of Pyridines

An iron(III)-porphyrin-catalyzed cyclization of ketones with dimethyl sulfoxide (DMSO) and ammonium acetate for the synthesis of unsymmetrical and symmetrical pyridines by employing DMSO as C-4 or C-6 source has been developed. Various aryl ketone derivatives react readily with DMSO, producing the pyridines in yields of 30%similar to 85%. This method uses non-noble metals and proceeds under mild reaction conditions with operational simplicity, which thus allows the expedient assembly of pyridines from readily available ketones. Based on the preliminary experiments, a plausible mechanism of this transformation is disclosed.