Ni-Catalyzed Alkenylation of Ketone Enolates under Mild Conditions: Catalyst Identification and Optimization

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• 作者：Michael Grigalunas ; Tobias Ankner ; Per-Ola Norrby ; Olaf Wiest ; Paul Helquist
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：June 10, 2015
• 年：2015
• 卷：137
• 期：22
• 页码：7019-7022
• 全文大小：292K
• ISSN：1520-5126

文摘

A procedure for Ni-catalyzed cross-coupling of ketone enolates with alkenyl halides has been developed. Intermolecular coupling of aromatic and aliphatic ketone lithium enolates with a variety of alkenyl halides is achieved in the presence of Ni(cod)₂ catalyst (5 mol %), an N-heterocyclic carbene (NHC) ligand, and LiI (10 mol %) at 6鈥?2 掳C for 0.5鈥?2 h with yields of up to 90%. During the initial development of this reaction, a misleading result with respect to the actual active catalyst was obtained using commercially available Q-Phos ligand, which was found to contain a trace of Pd metal contaminant sufficient to catalyze the reaction. However, under the final conditions optimized for Ni(cod)₂ in the presence of an NHC ligand, Pd was incompetent as a catalyst.