Palladium catalyzed direct 3-arylation of benzofurans using low catalyst loadings.

The palladium-catalyzed direct 3-arylation of benzofurans provides a cost-effective and environmentally attractive route for the preparation of 3-arylbenzofuran derivatives. The reactions were carried out using a wide variety of electronically and sterically diverse aryl or heteroaryl bromides with low catalyst loadings. In the presence of only 0.1-0.5 mol % catalyst, products in moderate to good yields were obtained. The aryl bromide reactants were able to tolerate a wide range of functionalities, such as acetyl, propionyl, formyl, ester, nitrile, trifluoromethyl, or fluoro groups. Higher yields were obtained using electron-deficient aryl bromides as reactants compared to using electron-rich aryl bromides. Functionalized benzofuran derivatives, bearing formyl or hydroxymethyl on C2, were also successfully employed.