Chemoselective oxygen-centered radical cyclizations onto silyl enol ethers

Organic Letters

Volumn 10, Issue 21, 2008, Pages 5083-5086

  Zlotorzynska, Maria ^a   Zhai, Huimin ^a   Sammis, Glenn M ^a  

^a UNIVERSITY OF BRITISH COLUMBIA   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

ALKENE; ETHER DERIVATIVE; FREE RADICAL; FURAN DERIVATIVE; OXYGEN; SILANE DERIVATIVE; TETRAHYDROFURAN; TIN;

ARTICLE; CHEMICAL STRUCTURE; CHEMISTRY; CYCLIZATION; SYNTHESIS;

ALKENES; CYCLIZATION; ETHERS; FREE RADICALS; FURANS; MOLECULAR STRUCTURE; OXYGEN; SILANES; TIN;

EID: 58149159589     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol802142k     Document Type: Article

References (42)

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22. To the best of our knowledge, there is only one example of the use of a silyl enol ether as an acceptor for an oxygen-centered radical cyclization. In the course of a study on β-fragmentations, there is one example of an oxygen-centered radical addition to a silyl enol ether in which the system is directed to cyclize onto the carbon α to the siloxy substituent. Kim, S.; Kim, K. H.; Cho, J. R. Tetrahedron Lett. 1997, 38, 3915-3918.
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33. Substrates 8a-h are Z-enriched. See the Supporting Information for E/Z ratios.
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37. 1H NMR mixtures. Therefore, it is still possible that they are present in <5% overall yield.
38. The diastereoselectivity dropped to 88:12 when E-enriched silyl enol ether 8g was used.
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42. Tetrahydropyrans can be formed in high yield from oxygen-centered radical 6-exo cyclizations when the allylic position is fully substituted and there are no allylic hydrogen atoms available for abstraction. For representative examples, see refs 10 and 23b