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Synfacts 2010(12): 1385-1385  
DOI: 10.1055/s-0030-1258887
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

A Lewis Acid Catalyzed Asymmetric Photocycloaddition

Contributor(s): Mark Lautens, Stephen G. Newman
H. Guo, E. Herdtweck, T. Bach*
Technische Universität München, Garching, Germany
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Publication History

Publication Date:
22 November 2010 (online)

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Significance

Enantioselective photochemical ­reactions are inherently difficult due to the high ­energy of the excited intermediates. Over two decades ago, the [2+2] photocycloaddition of coumarin was found to be enhanced by the addition of a Lewis acid (F. D. Lewis, S. V. Barancyk J. Am. Chem. Soc. 1989, 111, 8653). In the present communication, the authors disclose an intramolecular, enantioselective variant of this reaction, ­revealing a new concept for asymmetric induction of photochemical reactions.