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DOI: 10.1055/s-2008-1078624
Co-Catalyzed Cyclooctatriene Synthesis by [4+2+2] Cycloaddition
Contributor(s):Paul Knochel, Andreas J. WagnerPhilipps-Universität Marburg, Germany
Cobalt-Catalyzed [4+2+2] Cycloaddition for the Synthesis of 1,3,6-Cyclooctatrienes
Angew. Chem. Int. Ed. 2008, 47: 5243-5245
Publication History
Publication Date:
22 August 2008 (online)
Key words
alkynes - cobalt - cycloaddition - medium-ring compounds - regioselectivity
Significance
This atom-economical reaction catalyzed by a Co-diimine complex provides access to a number of functionalized cyclooctatrienes in good yields. Internal alkynes give the highly substituted products in somewhat lower yields. It has been found that the use of Fe powder increases the yield of cyclooctatriene.
Comment
In most cases, Diels-Alder type side products are observed, which are however easily removable by chromatography. Both the regioselectivity as well as the fact that no excess of alkyne is required are the main attractive features of this new synthesis of unsaturated medium-sized carbocycles.