Iridium-Catalyzed and Ligand-Controlled Carbonylative Synthesis of Flavones from Simple Phenols and Internal Alkynes.

Flavones are important natural products with diverse biological activities. In this study, a novel procedure for the carbonylative synthesis of flavones has been developed by using simple phenols and internal alkynes as the substrates. Various flavones were isolated in moderate to good yields with excellent regioselectivity and functional group tolerance by using an iridium catalyst system. Notably, this is the first example of direct carbonylative annulation of non-preactivated phenols and alkynes to produce flavones, with the choice of ligand proving to be critical for the success of this transformation.