A first regioselective synthesis of 3-fluoroalkylated benzofurans via palladium-catalyzed annulation of fluorine-containing internal alkynes with variously substituted 2-iodophenol

The palladium-catalyzed annulation reaction of a variety of fluorine-containing internal alkynes with 2-iodophenol derivatives was investigated. The use of P(t-Bu)3 as a ligand on palladium was found to be crucial in this annulation reaction, resulting in the exclusive formation of 3-fluoroalkylated benzofurans in high yields. 19F NMR analysis of the reaction mixture revealed that the addition of phenol to the fluoroalkylated alkynes was followed by intramolecular Heck reaction, giving to the corresponding 3-fluoroalkylated benzofurans.