Skeletal and Peripheral Editing of Pyridinium Salts into Fully Substituted Pyrroles

A mild and efficient skeletal editing strategy for the synthesis of fully substituted pyrroles from pyridinium salts is described. The transformation proceeds through a sequence of pyridinium salt ring opening, imidation, ring closing, and bromination steps, demonstrating broad substrate scope, good functional group tolerance, and scalability to the gram scale. Mechanistic studies support a pathway involving the regioselective addition of a succinimidyl radical to a Zincke aldehyde intermediate, followed by cyclization and bromination. The resulting pyrrole products are equipped with multiple orthogonal functional handles that enable diverse downstream derivatization.