Synthesis of benzofuro- and benzothieno[2,3-c]pyridines via copper-catalyzed [4 + 2] annulation of ketoxime acetates with acetoacetanilide

Abstract

An efficient copper-catalyzed annulation of ketoxime acetates with acetoacetanilide has been developed. This strategy provides an alternate route towards the synthesis of benzofuro- and benzothieno[2,3-c]pyridines with good functional group tolerance and operational simplicity. Mechanistic investigation indicates that an ionic pathway rather than a radical pathway was involved in the transformation.