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Synfacts 2008(4): 0400-0400
DOI: 10.1055/s-2008-1042869
DOI: 10.1055/s-2008-1042869
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York
Lewis Acid Catalyzed Nazarov Cyclization of Dienones Bearing Polar Substituents
W. He, I. R. Herrick, T. A. Atesin, P. A. Caruana, C. A. Kellenberger, A. J. Frontier*
University of Rochester, USA
Further Information
Publication History
Publication Date:
19 March 2008 (online)
![](https://www.thieme-connect.de/media/synfacts/200804/lookinside/thumbnails/10.1055-s-2008-1042869-1.jpg)
Significance
The impact of various polar substitution patterns of the dienone on the Lewis acid catalyzed Nazarov cyclization has been systematically studied. The general trends of steric and electronic factors are summarized as follows: (1) Substrates with oxygen substituent at C-2 react faster than those with alkyl substituent; (2) internal substituents at C-1 slow down the reaction due to unfavorable steric effects; (3) E,Z-isomerization can lead to stereoconvergent cyclization of mixtures, and this also influences the observed reaction rate with different C4 and C5 substituents.