Cooperative Catalysis with Aldehydes and Copper: Development and Application in Aerobic Oxidative CH Amination at Room Temperature

A conceptually new cooperative catalytic system via a synergistic combination of aldehyde and copper catalysis has been established based on systemic mechanistic studies. This new cooperative catalysis has been successfully applied in the direct aerobic oxidative CH amination of azoles at room temperature, which was previously realized under harsh conditions. Mechanistic studies including isotopic labeling experiments and kinetic isotope effect (KIE) experiments support a reaction pathway that involves formation of an aminal, hydrolysis of the aminal to generate the copper-amide species, subsequent CH amination and re-oxidation of copper(I) to copper(II) by oxygen. It not only provides an efficient method to realize the oxidative CH amination of benzoxazoles with free amines at room temperature, but also paves the way for establishing new CN bond formation reactions by using this efficient cooperative catalysis.