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Updated: Jun 15, 2025

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Pd/Cu Dual Metal-Catalyzed Regioselective [2 + 2 + 2] Cycloaddition of Malononitriles with Alkynes to Densely
Xing-Zhen Wang1, Hong-Gui Huang1, Wen-Bo Liu1,2
1Hubei Research Center of Fundamental Science-Chemistry, Engineering Research Center of Organosilicon Compounds & Materials (Ministry of Education), Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, and College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Abstract:
Transition metal-catalyzed [2 + 2 + 2] cycloaddition of nitriles and two alkynes is an efficient method for assembling pyridines. However, examples employing palladium catalysis have rarely been disclosed, and the processes of reactivity and selectivity remain unclear. We report here a palladium/copper dual metal-catalyzed [2 + 2 + 2] cycloaddition of diynyl-tethered malononitriles and terminal alkynes to synthesize densely substituted pyridines. This method features a good substrate scope, synthetically useful yields, and perfect regioselectivity. The derivatization of the pyridine products demonstrates the potential application of this method in synthesizing heterocycles and as ligands in photocatalysis. Preliminary mechanistic studies suggest that the reaction undergoes aza-oxidative cycloaddition of Pd(0) with nitrile and alkyne, followed by alkyne insertion and reductive elimination. The presence of copper is crucial to its reactivity and regioselectivity.
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