Palladium/copper bimetallic system-catalyzed cascade cyclization of N-allyl Ynamides and o-haloanilines: access to multifunctional benzimidazoles

Abstract

A one-pot synthesis of 1,2-disubstituted multifunctional benzimidazole derivatives starting from N-Allyl Ynamides and o-Haloanilines has been introduced. The mechanistic study suggests that the reaction proceeds via a Pd-catalyzed nucleophilic addition of N-allyl ynamides to the amino group of the o-haloanilines to form a amidine intermediate, followed by Cu-catalyzed intramolecular cyclization. The reaction could also be performed on a multi-gram scale with the same efficiency.