Palladium-catalyzed intramolecular coupling-cyclization of 3-(cyclohexa-2,4-dienyl)pentane-2,4-dione with β-styryl bromides proceeds in regio- and stereoselective fashions to give 2-styryl-substituted bicyclo[4.1.0]hept-3-enes in good yields. The formation of the bicyclo[4.1.0]hept-3-enes was rationalized by starting with oxidative addition of Pd(PPh3)4 to the carbon-bromine bond of β-styryl bromide (RBr) to give Pd(R)BrLn. Reaction of Pd(R)BrLn with Ag 2CO3 generates a cationic RPd(II)Ln species. Chelation of the RPd(II)Ln cation to both the O-enolate of the ketone and the proximal double bond followed by attack of the enolate on the activated double bond gave a bicyclic η1-allylpalladium intermediate. The postulated bicyclic η1-allylpalladium intermediate leads to 2-styryl-substituted bicyclo[4.1.0]hept-3-enes with exclusive regio- and stereoselectivities after reductive elimination.
|Number of pages||7|
|Publication status||Published - 2007 Aug 13|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
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CCDC 664437: Experimental Crystal Structure Determination
Yeh, M. P. (Creator), Tsao, W. (Creator), Wang, Y. (Creator) & Pai, H. (Creator), Unknown Publisher, 2008
DOI: 10.5517/ccq9dgv, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccq9dgv&sid=DataCite