Intramolecular Hydroalkoxylation and Hydroamination of Alkynes Catalyzed by Cu(I) Complexes Supported by N-Heterocyclic Carbene Ligands
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- 作者：Mark J. Pouy ; Samuel A. Delp ; Jamal Uddin ; Vijay M. Ramdeen ; Nikki A. Cochrane ; George C. Fortman ; T. Brent Gunnoe ; Thomas R. Cundari ; Michal Sabat ; William H. Myers
- 刊名：ACS Catalysis
- 出版年：2012
- 出版时间：October 5, 2012
- 年：2012
- 卷：2
- 期：10
- 页码：2182-2193
- 全文大小：572K
- 年卷期：v.2,no.10(October 5, 2012)
- ISSN：2155-5435
文摘
Intramolecular addition of O鈥揌 and N鈥揌 bonds across carbon鈥揷arbon triple bonds to form 5- or 6-membered rings with exocyclic methylene groups for ether products and exocyclic methyl groups for imine products is catalyzed by (IPr)Cu(Me) (IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene). In a competition study, the cyclization of primary amines was found to be faster than that of alcohols. Kinetic studies for the conversion of 4-pentyn-1-ol reveal that the catalytic reaction is first-order in copper catalyst and zero-order in alkynyl alcohol, and an Eyring analysis yields 螖H鈥?/sup> = 18.7(4) kcal/mol and 螖S鈥?/sup> = 鈭?6(1) eu. The reaction of 5-phenyl-4-pentyn-1-ol provides (Z)-2-benzylidene-tetrahydrofuran in high yield and with quantitative stereoselectivity. Results from combined experimental and DFT studies are consistent with a mechanism that involves alkyne insertion into a Cu鈥揙alkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol.