Regiospecific Skeletal Editing of Azetines toward Halogenated Pyrroles

The regiospecific ring expansion of 2H-azetines into halogenated pyrroles is disclosed. Simple reaction sequences have been developed to conceptualize this 4 → 5 skeletal editing strategy, taking advantage of the inherent reactivity of double bonds present in the initial four-membered ring systems. Detailed density functional theory (DFT) calculations are presented to explain this unusual rearrangement. Such a reaction design allows for the preparation of highly substituted halogenated pyrrole derivatives.