ORGN 457 |
Platinum bisoxazoline pincer complexes as catalysts for the asymmetric Michael reaction
| Christopher J. Richards, Huy V. Nguyen, and John S. Fossey. Department of Chemistry, Queen Mary, University of London, Mile End Road, London, United Kingdom |
Platinum bisoxazoline pincer complexes are generated in one-step by simply heating 1,3-bisoxazolines (1) with K2PtCl4 in acetic acid. Subsequent halide abstraction with silver salts gives cationic complexes (2) that are applicable as chiral Lewis acid catalysts. For example, use of (2a) in the Michael reaction between methyl vinyl ketone and ethyl ?-cyanopropionate (3) results in the formation of (R)-(4) in up to 36% e.e. Intriguingly, the e.e. of (4) increases during the course of the reaction which is also accompanied by a modest kinetic resolution of the nitrile ester (3) (selectivity factor S=1.5). Optimisation studies on this process and other applications of (2) will also be reported. |
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Total Synthesis, Asymmetric Reactions and Syntheses, Bioorganic
9:00 AM-11:00 AM, Wednesday, March 31, 2004 Anaheim Convention Center -- Hall C, Poster
Division of Organic Chemistry
The 227th ACS National Meeting, Anaheim, CA, March 28-April 1, 2004
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