Facile and efficient synthesis of polyfunctionalized benzofurans: three-component coupling reactions from an alkynylsilane, an o-hydroxybenzaldehyde derivative, and a secondary amine by a Cu(I)–Cu(II) cooperative catalytic system

Abstract

The combination of 5 mol % Cu(OTf) 2 and CuCl in the presence of DMAP effectively catalyzed a three-component coupling reaction involving an alkynylsilane, an o-hydroxybenzaldehyde derivative, and a secondary amine. The reaction proceeded via intramolecular 5- exo- dig cyclization, resulting in direct synthesis of the corresponding benzofuran derivatives in moderate to excellent yields.