DIVERGENT SYNTHESIS OF INDOLE-2-CARBOXYLIC ACID DERIVATIVES VIA LIGAND-FREE COPPER-CATALYZED ULLMANN COUPLING REACTION

摘要

This article describes a ligand-free copper-catalyzed Ullmann coupling reaction for the preparation of divergent indole-2-carboxylic acid derivatives including esters, amides and anhydrides. Various compounds 3, which could be synthesized from aldehydes conveniently, were used as substrate to provide the corresponding indole-2-carboxylic acid derivatives in moderate to good yields.