Asymmetric Cooperative Catalysis of Strong Brønsted Acid–Promoted Reactions Using Chiral Ureas
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- Hao Xu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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- Stephan J. Zuend
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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- Matthew G. Woll
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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- Ye Tao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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- Eric N. Jacobsen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
書誌事項
- 公開日
- 2010-02-19
- DOI
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- 10.1126/science.1182826
- 公開者
- American Association for the Advancement of Science (AAAS)
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説明
<jats:title>Acid Assistance</jats:title> <jats:p> Protons are quite versatile catalysts of organic reactions, but because they are achiral, they cannot induce stereoselectivity on their own. One productive way around this problem has been to use chiral conjugate bases and perform reactions in media where the bases remain tightly attracted to protonated substrates. <jats:bold> Xu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="986" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1182826">986</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5968" page="965" related-article-type="in-this-issue" vol="327" xlink:href="10.1126/science.1186764">Schreiner</jats:related-article> </jats:bold> ) thoroughly explored the mechanism of an alternative approach, in which an achiral acid was used in conjunction with a second, chiral molecule (a urea derivative) for catalysis. High selectivity was attained with this method in the coupling of aryl imines with olefins. Extensive kinetic and computational studies showed that the acid and its chiral partner acted cooperatively in binding the substrates, optimizing the tradeoff between speed and selectivity. </jats:p>
収録刊行物
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- Science
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Science 327 (5968), 986-990, 2010-02-19
American Association for the Advancement of Science (AAAS)