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Synfacts 2008(4): 0400-0400  
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

Contributor(s): Hisashi Yamamoto, Pingfan Li
W. He, I. R. Herrick, T. A. Atesin, P. A. Caruana, C. A. Kellenberger, A. J. Frontier*
University of Rochester, USA
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Publication History

Publication Date:
19 March 2008 (online)

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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.