Benzofuran Derivatives from Alkynyl-Substituted Benzynes and Aryl Halides

A palladium(0)-catalyzed cascade reaction for the efficient synthesis of 2,3-disubstituted benzofuran derivatives 3 containing a 3-trisubstituted alkene functional group in moderate yields from alkynyl-substituted benzynes 1 and aryl halides 2 has been developed. This method provides an efficient and alternative approach to benzofurans which are very useful heterocyclic compounds with biological and pharmacological potentials. A plausible mechanism involving intramolecular ene reaction, intermolecular insertion, and β-H elimination is proposed.