Synthesis 2008(1): 75-78  
DOI: 10.1055/s-2007-990930
PAPER
© Georg Thieme Verlag Stuttgart · New York

Cobalt-Catalyzed [2+2+2] Cycloaddition of Phenylacetylene with 1,3-Dienes for the Synthesis of Vinyl-Substituted 1,4-Diphenylcyclohexa-1,3-dienes

Gerhard Hilt*, Wilfried Hess, Klaus Harms
Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35043 Marburg, Germany
Fax: +49(6421)2825677; e-Mail: Hilt@chemie.uni-marburg.de;
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Received 2 October 2007
Publikationsdatum:
28. November 2007 (online)

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Abstract

The cobalt-catalyzed [2+2+2] cycloaddition of two alkynes and a 1,3-diene, utilizing either a dibromo[1,2-bis(diphen­ylphosphino)]benzene cobalt or a dibromobis(triphenylphosphino)cobalt complex, under reductive conditions gives vinyl-substituted cyclohexa-1,3-diene derivatives in acceptable yields. The oxidation of 5-methyl-1,4-diphenyl-5-vinylcyclohexa-1,3-diene by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone leads to a rearrangement resulting in a vinyl-terphenyl derivative.