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Synfacts 2005(0): 0083-0083  
DOI: 10.1055/s-2005-869885
Polymer-Supported Synthesis
© Georg Thieme Verlag Stuttgart · New York

A Poly(ethylene glycol)-Supported Chiral Auxiliary for Asymmetric Michael Reaction

Contributor(s): Yasuhiro Uozumi, Yoichi M. A. Yamada, Takayasu Arakawa
B. Kreidler, A. Baro, J. Christoffers*
Universität Stuttgart, Germany
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Publication History

Publication Date:
20 July 2005 (online)

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Significance

Poly(ethylene glycol)-supported l-valine-derived auxiliary 1 was prepared from poly(ethylene glycol) dimesylate in four steps. After condensation with ethyl cyclopentan-2-one carboxylate and ethyl cyclohexan-2-one carboxylate, copper-catalyzed Michael reactions of the resulting enamines 2 with methyl vinyl ketone were carried out at 23 °C for two days in acetone to give ethyl (R)-2-oxo-1-(3-oxobutyl)cyclopentane carboxylate and ethyl-(R) 2-oxo-1-(3-oxobutyl)cyclohexane carboxylate with 99% ee and 97% ee, respectively. Auxiliary 1 was recovered by simple precipitation from diethyl ether.