Reduction system ‘vitamin C/glycerol’ promoted copper (II)‐catalyzed N ‐arylation

Abstract The common access to forming CN bond is the copper‐catalyzed Ullmann‐type reaction. The relatively expensive and easily oxidized copper(I) is usually used in the reaction. Our group discovered that the “vitamin C/glycerol” reduction system could convert cheap and stable CuO to active low valence state copper species, as measured via X‐ray photoelectron spectroscopy (XPS), to promote the CN coupling reaction. In particular, 2‐phenylindole, pyrrolo[1,2‐ a ]quinoxaline, 1,2,4‐triazole and 4‐amino‐7 H ‐pyrrolo[2,3‐ d ]pyrimidine derivative were obtained in the presence of CuO and reduction system “vitamin C/glycerol.” This method provided a simple and cost‐effective approach to the preparation of N ‐arylation products.