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.