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Synfacts 2008(11): 1216-1216  
DOI: 10.1055/s-0028-1083387
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

Simple Carboxylic Acids as Cofactor in Asymmetric Protonation

Contributor(s): Benjamin List, Lars Ratjen
T. Poisson, S. Oudeyer, V. Dalla, F. Marsais, V. Levacher*
INSA - Université de Rouen, Mont-Saint-Aignan and Université du Havre, Le Havre, France
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Publication History

Publication Date:
23 October 2008 (online)

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Significance

The asymmetric protonation of silyl enolates with a combination of cinchona alkaloid catalysts, such as 1, and simple carboxylic acids as proton source is described. The reaction is assumed to occur via initial protonation of the amine catalyst to form a salt. The role of the carboxylate counteranion seems to be the activation of the silyl group of the enolate. Subsequently the enolate is protonated by the chiral ammonium ion, furnishing the desired product in enantioenriched form.