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New Polymer-Supported Mono- and Bis-Cinchona Alkaloid Derivatives: Synthesis and Use in Asymmetric Organocatalyzed Reactions.
- Source :
- Chemistry - An Asian Journal; Feb2015, Vol. 10 Issue 2, p397-404, 8p
- Publication Year :
- 2015
-
Abstract
- The straightforward synthesis of polystyrene-supported Chinchona alkaloids and their application in the asymmetric dimerization of ketenes is reported. Six different immobilized derivatives, consisting of three dimeric and two monomeric 9-O ethers, were prepared by "click" anchoring of soluble alkaloid precursors on to azidomethyl resins. The resulting insoluble polymer-bound (IPB) organocatalysts were employed for promoting the dimerization of in-situ generated ketenes. After opening of the ketene dimer intermediates with N,O-dimethylhydroxylamine, valuable Weinreb amides were eventually obtained in good yield (up to 81%) and excellent enantiomeric purity (up to 96% ee). All of the IPB catalysts could be recycled effectively without significant loss of activity and enantioselectivity. The extension to other asymmetric transformations (meso-anhydride desymmetrization and α-amination of 2-oxindoles) is also briefly discussed. [ABSTRACT FROM AUTHOR]
- Subjects :
- ALKALOIDS
CINCHONA
CLICK chemistry
POLYMER blends
DIMERIZATION
KETENES
CATALYSIS
Subjects
Details
- Language :
- English
- ISSN :
- 18614728
- Volume :
- 10
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Chemistry - An Asian Journal
- Publication Type :
- Academic Journal
- Accession number :
- 103550383
- Full Text :
- https://doi.org/10.1002/asia.201402924