A library of C-3 functionalized flavones was successfully provided via palladium-catalyzed amino- and aryloxycarbonylation reactions of 3-iodoflavone (1), 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 (2a-t) were produced in 22-79%, the flavone-3-carboxylates (4a'-l') were obtained in excellent yields (up to 88%), under identical reaction conditions, just by switching N-nucleophiles to O-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 (2r) and flavone-3-ester (4f') were further studied by single-crystal XRD analysis.
Keywords: aminocarbonylation; aryloxycarbonylation; carbon monoxide; flavon-3-carboxamides; flavone-3-carboxylates.