An unusual ring expansion from the Zav’yalov pyrrole synthesis: formation of oxacino[2,3-c]pyrroles

Abstract

Enamino acids 2 and 5 undergo a facile cyclisation to afford the pyrrole 3 and isoindole 6 ring systems; a novel two atom ring expansion ensues when derivatives 5b,d are subjected to the cyclisation conditions, resulting in the formation of the new oxacino[2,3-c]pyrrole system, the structure of which is confirmed by X-ray crystallography.