Divergent [3+2] annulations of oxime acetates with thioaurones/aurones leading to benzothiazino-/benzoyl-pyrroles

Abstract

Herein, we report the development of unprecedented copper-catalyzed intramolecular annulations of oxime acetates with thioaurones/aurones (different reactivity observed) providing benzothiazino-/benzoyl-pyrroles in high yield. The key steps involved in the present cascade approach are [3+2] spiroannulation, followed by oxidation and rearrangement or aromatisation, depending on the substrate used. The synthetic utility of the resulting product to construct a benzo[6,7]oxepino[4,3-b]pyrrole scaffold is also demonstrated.