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Synfacts 2008(2): 0178-0178  
DOI: 10.1055/s-2007-992445
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Regio- and Enantioselective Cycloadditions of Nitrones

Contributor(s):Hisashi Yamamoto, Marina Naodovic
T. Hashimoto, M. Omote, T. Kano, K. Maruoka*
Kyoto University, Japan
Asymmetric 1,3-Dipolar Cycloadditions of Nitrones and Methacrolein Catalyzed by Chiral Bis-Titanium Lewis Acid: A Dramatic Effect of N-Substituent on Nitrone
Org. Lett.  2007,  9:  4805-4808  
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Publication History

Publication Date:
23 January 2008 (online)

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Key words

titanium - 1,3-dipolar cycloaddition - nitrones

Significance

This is one of the rare examples of a successful protocol for highly regio- and enan­tioselective cycloaddition of nitrones and meth­acrolein. The most important features of this methodology are the high regioselectivity observed and the generation of a quaternary stereocenter. Furthermore, the method can be efficiently employed for the reaction with crotonaldehyde.

Comment

A novel strategy that circumvents longstanding difficulties associated with cycloaddition of nitrones is introduced. More specifically, by introduction of sterically more demanding N-substituent (DMP-group), the LA-nitrone complex can be kinetically destabilized due to steric congestion.

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