ORGN 546 |
| The vinylogous Mukaiyama aldol reaction is a synthetically powerful carbon-carbon bond forming reaction in which up to two stereocenters and one double bond can be created at the same time. Recently we have developed a method for highly g-selective vinylogous aldol additions of silyl dienol ethers derived from both a,b-unsaturated ketones and amides. The catalyst system of silicon tetrachloride (SiCl4) activated by chiral bisphosphoramide (R,R)-1 promotes the addition of both g-substituted and unsubstituted silyl dienol ethers to a variety of aldehydes with exclusive g-site selectivity and good to excellent diastereo- and enantioselectivity. This presentation will discuss the scope and limitations of these reactions, along with the synthetic utility of the a,b-unsaturated amide aldolates. The effect of different nitrogen substitutents on the selectivity of these vinylogous aldol additions will also be discussed.
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Asymmetric Reactions and Syntheses
1:00 PM-5:00 PM, Wednesday, 31 August 2005 Washington DC Convention Center -- 201, Oral
Division of Organic Chemistry |
