Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/17574
Title: Chiral bicyclic guanidine catalyzed michael reactions
Authors: YE WEIPING
Keywords: chiral guanidine, asymmetric catalysis, Michael reaction
Issue Date: 16-Dec-2006
Source: YE WEIPING (2006-12-16). Chiral bicyclic guanidine catalyzed michael reactions. ScholarBank@NUS Repository.
Abstract: The aim of this study is to develop a highly enantioselective Michael reaction catalyzed by chiral bicyclic guanidines.1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), a bicyclic guanidine base, was found to be an excellent catalyst for Michael and Michael-type reactions. A series of chiral bicyclic guanidines, both symmetrical and non-symmetrical, were synthesized using a concise and efficient aziridine-based synthetic methodology. One of the synthesized chiral bicyclic guanidine was found to be a highly enantioselective organocatalyst for the Michael reactions between 2-cyclopenten-1-one and various 1,3-dicarbonyl compounds, including dialkyl malonates, benzoylactetates, and S,Sa??-dialkyl dithiomalonates. The enantioselectivities generally range from 86-96%, with yields between 84-99%.The substrate scope of the chiral bicyclic guanidine catalyzed Michael reaction was expanded to include N-alkyl maleimides. The enantioselectivities generally range from 90-96%, with yields between 91-99%. The methodology has been applied to the first enantioselective synthesis of (S)-(+)-homo-i??-proline, which is a potent GABA agonist and uptake inhibitor.
URI: http://scholarbank.nus.edu.sg/handle/10635/17574
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