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Synfacts 2008(8): 0834-0834  
DOI: 10.1055/s-2008-1078552
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Kilogram-Scale Asymmetric Rhodium-Catalyzed 1,4-Addition

Contributor(s): Hisashi Yamamoto, Joshua N. Payette
S. Brock, D. R. J. Hose, J. D. Moseley, A. J. Parker*, I. Patel, A. J. Williams
AstraZeneca, Bristol, UK
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Publication History

Publication Date:
23 July 2008 (online)

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Significance

The authors describe the implementation of an enantioselective rhodium-catalyzed 1,4-conjugate addition of 3,5-difluorophenyl boronic acid to various α,β-unsaturated esters. Remarkably, while previous reports required 2-10 equivalents of boron species due to a rhodium-mediated protodeboronation pathway, the authors found that the use of one equivalent of i-PrOH instead of water significantly suppressed this side reaction.