The first addition of silyl enol ethers to internal unactivated alkynes

Tetrahedron Letters

Volumn 40, Issue 21, 1999, Pages 4081-4084

  Imamura, Ken Ichiro ^a   Yoshikawa, Eiji ^a   Gevorgyan, Vladimir ^a   Yamamoto, Yoshinori ^a  

^a TOHOKU UNIVERSITY   (Japan)

Author keywords

Alkynes; Carbocyclization; Lewis acid; Silyl enol ethers

Indexed keywords

2 CYCLOHEXENONE; ACETYLENE; ALKYNE DERIVATIVE; HETEROCYCLIC COMPOUND; KETONE; SILANE DERIVATIVE;

ARTICLE; CHEMICAL REACTION; CHEMICAL STRUCTURE; CYCLIZATION; GAS CHROMATOGRAPHY; MASS SPECTROMETRY; ORGANIC CHEMISTRY; PROTON NUCLEAR MAGNETIC RESONANCE; THERMODYNAMICS;

EID: 0033591147     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)00654-1     Document Type: Article

References (27)

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15. 6. While this project was under investigation in our labs, a paper describing a W-catalyzed endo-selective carbocyclization of silyl enol ethers with terminal alkynes has appeared. See: Maeyama, K.; Iwasawa, N. J. Am. Chem. Soc. 1998, 120, 1928.
16. 7. Mercury-mediated carbocyclization approach was recently successfully used for natural products synthesis. See: (a) Frontier, A. J.; Raghavan, S.; Danishefsky, S. J. J. Am. Chem. Soc. 1997, 119, 6686.
17. (b) See also ref 5c.
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21. 3, in some cases gave the carbocyclization products although the chemical yields with these Lewis acids were low (≤ 40 %).
22. 11. The control experiments have confirmed that ß,y-enone 10 is the kinetic product, which isomerizes into the thermodynamic product, α,ß-enone 11, under the reaction conditions. Thus, normally the carbocyclization of 9c gives about a 95:5 ratio of 10c:11c (eq 3); after being stirred for an additional 3 hours at room temperature the ratio changes to 44:56, whereas after 12 hours the isomeric 11c becomes the major reaction product accompanied by a trace amount of 10c.
23. 16O 200.1201, found 200.1201.
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