Palladium-Catalyzed Decarboxylative Cross-Coupling Reactions: A Route for Regioselective Functionalization of Coumarins

A straightforward, regioselective, and step-economical ligand-free palladium-catalyzed decarboxylative functionalization of coumarin-3-carboxylic acids is devised. This protocol is compatible with a wide variety of electron-donating and -withdrawing substituents and allows for construction of various biologically important π-electron extended coumarins.