Twofold 4-to-6 ring expansion of azetines to bis-halogenated pyridines

Abstract

A sequence of two consecutive skeletal editing steps through carbon insertions has been developed and allows the regioselective ring expansion of functionalized 2H-azetines to 3,5-bis-halogenated pyridines via the intermediate formation of 3-halopyrroles. The in situ generation of halogenated carbenes is used to challenge such a 2-step transformation and provides access to a large library of uniquely sophisticated structures.