Sequential Addition of Phosphine to Alkynes for the Selective Synthesis of 1,2-Diphosphinoethanes under Catalysis. Well-Defined NHC-Copper Phosphides vs in Situ CuCl2/NHC Catalyst

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• 作者：Jia Yuan ; Lizhao Zhu ; Jianying Zhang ; Jianfeng Li ; Chunming Cui
• 刊名：Organometallics
• 出版年：2017
• 出版时间：January 23, 2017
• 年：2017
• 卷：36
• 期：2
• 页码：455-459
• 全文大小：347K
• ISSN：1520-6041

文摘

The well-defined NHC-copper phosphides [(NHC)CuPPh₂]₃ (1, NHC = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (IⁱPr); 2, NHC = N,N-di-tert-butylimidazol-2-ylidene (I^tBu)) have been prepared by the reaction of simple copper halides with HPPh₂ in the presence of N-heterocyclic carbenes (NHCs). Complexes 1 and 2 enabled catalytic double hydrophosphination of alkyl and aryl terminal alkynes to yield 1,2-diphosphinoethanes selectively in good yields. On the basis of these results, the most efficient and pratical in situ CuCl₂/NHC catalyst has been developed. It catalyzes the selective double hydrophosphination of the alkynes with high efficiency and a wide substrate scope and exhibits even better performance than the well-defined NHC-Cu phosphides. The mechanistic studies disclosed that the formation of a copper acetylide in the catalytic cycle played an important role in the acceleration of the catalytic process.