ORGN 24 |
| The conjugate addition of α-substituted 1, 3-dicarbonyl donors to α,β-unsaturated carbonyl compounds provides a powerful strategy for the creation of all-carbon quaternary stereocenters, due to the accessibility of a wide range of both the Michael donors and acceptors and the proven wide utility of the 1,4-adducts. We will present the development and synthetic applications of broadly effective catalytic asymmetric conjugate additions to carbonyl acceptors such as α,β-unsaturated ketones and aldehydes. These reactions utilize readily available bifunctional organic catalysts derived from cinchona alkaloids. The enantioselectivity achieved under modified conditions is unprecedented, ranging from 80-99%. Excellent enantioselectivity(up to 99%) and diastereoselectivity(up to 25:1) were also obtained for reactions with α-substituted α,β-unsaturated carbonyl compounds as Michael donors. The applications of these reactions in catalytic enantioselective syntheses of the biologically interesting natural product will also be discussed. |
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Asymmetric Reactions and Syntheses
8:00 AM-12:20 PM, Sunday, 10 September 2006 Moscone Center -- Room 131, Oral
Division of Organic Chemistry |