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Synfacts 2006(3): 0278-0278
DOI: 10.1055/s-2006-931988
DOI: 10.1055/s-2006-931988
Bioorganic Chemistry and Organocatalysis
© Georg Thieme Verlag Stuttgart · New York
Conjugate Addition of α-Substitutedβ-Ketoesters to α,β-Unsaturated Ketones
F. Wu, H. Li, R. Hong, L. Deng*
Brandeis University, Waltham, USA
Further Information
Publication History
Publication Date:
21 February 2006 (online)
Significance
This paper describes the construction of quaternary stereocenters using an enantioselective conjugate addition of α-substituted β-ketoesters to α,β-unsaturated ketones catalyzed by 1-20 mol% of a 6′-hydroxy cinchona alkaloid. The reactions were mainly performed at room temperature under open flask conditions yielding the products in high enantioselectivities and diastereoselectivities. Importantly, excellent results were achieved not only for a variety of α-substituted β-ketoesters but also for a wide range of α,β-unsaturated ketones bearing both alkyl and aryl substituents. A bulky ester group in the nucleophile (R3 = tert-butyl- or isopropyl) is required to achive high enantioselectivity.