| Autor: |
Jamal Uddin, Michal Sabat, Nikki A. Cochrane, George C. Fortman, William H. Myers, Vijay M. Ramdeen, T. Brent Gunnoe, Mark J. Pouy, Samuel A. Delp, Thomas R. Cundari |
| Rok vydání: |
2012 |
| Předmět: |
|
| Zdroj: |
ACS Catalysis. 2:2182-2193 |
| ISSN: |
2155-5435 |
| Popis: |
Intramolecular addition of O–H and N–H bonds across carbon–carbon 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 ΔH‡ = 18.7(4) kcal/mol and ΔS‡ = −26(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–Oalkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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