The common access to forming CN 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 CN coupling reaction. In particular, 2‐phenylindole, pyrrolo[1,2‐a]quinoxaline, 1,2,4‐triazole and 4‐amino‐7H‐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.
Amides are a critical class of widely distributed heterocycles in nature. The preparation of amides from benzoic acids and dicarbodiimides under catalyst-free conditions was reported. Various products were obtained in good to high yields. The model reaction could be scaled up to the gram-scale level. A reaction mechanism was proposed based on control experiments and relevant literatures.
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