Enyne [4 + 4] Photocycloaddition: Bridged 1,2,5-Cyclooctatrienes

Enyne photocycloaddition with a 2-pyridone yields a mixture of products including amide-bridged 1,2,5-cyclooctatrienes, the first examples of enyne [4 + 4] adducts. Four regio- and stereochemical isomers of the [4 + 4] adduct are possible. All appear to be too strained to be isolated, but they have...

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Bibliographic Details
Published in:Organic letters 2010-08, Vol.12 (15), p.3296-3299
Main Authors: Kulyk, Svitlana, Dougherty, William G, Kassel, W. Scott, Fleming, Steven A, Sieburth, Scott McN
Format: Article
Language:English
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Summary:Enyne photocycloaddition with a 2-pyridone yields a mixture of products including amide-bridged 1,2,5-cyclooctatrienes, the first examples of enyne [4 + 4] adducts. Four regio- and stereochemical isomers of the [4 + 4] adduct are possible. All appear to be too strained to be isolated, but they have been identified as their [2 + 2] cyclobutane dimers. Cyclobutane and cyclobutene adducts have also been isolated, [2 + 2] addition products possibly related to the unstable [4 + 4] adducts via Cope rearrangement. Calculations suggest that [3,3] rearrangements have high energy barriers, however, making thermal interconversion unlikely.
ISSN:1523-7060
1523-7052
DOI:10.1021/ol1014174