A Facile Route to Flavone-3-Carboxamides and Flavone-3-Carboxylates via Palladium-Catalyzed Amino- and Aryloxy-Carbonylation Reactions

A library of C-3 functionalized flavones was successfully provided via palladium-catalyzed amino- and aryloxycarbonylation reactions of 3-iodoflavone (<b>1</b>), under mild conditions. This methodology showed good functional group tolerance using a variety of amines and phenols, under an atmospheric pressure of carbon monoxide as a carbonyl source. While the flavone-3-carboxamides (<b>2a-t</b>) were produced in 22-79%, the flavone-3-carboxylates (<b>4a'-l'</b>) were obtained in excellent yields (up to 88%), under identical reaction conditions, just by switching <i>N</i>-nucleophiles to <i>O</i>-nucleophiles. The convenient availability of the involved starting materials confers simplicity to this approach to design new C-3-substituted flavones of biological relevance. The solid-state structures of flavone-3-carboxamide (<b>2r</b>) and flavone-3-ester (<b>4f'</b>) were further studied by single-crystal XRD analysis.