reactions enabled the asymmetric synthesis of deoxysugars with >99 % ee. In addition, the direct amino acid catalyzed C(2)+C(2)+C(2) methodology is a new entry for the short, highly enantioselective denovosynthesis of carbohydrate derivatives, isotope-labeled sugars, and polyketide natural products. The one-pot asymmetric denovo syntheses of deoxy and polyketide carbohydrates involved a novel dynamic kinetic
[EN] DIRECT, ENANTIOSELECTIVE ALDOL COUPLING OF ALDEHYDES USING CHIRAL ORGANIC CATALYSTS<br/>[FR] COUPLAGE ALDOLIQUE ENANTIOSELECTIF DIRECT D'ALDEHYDES A L'AIDE DE CATALYSEURS ORGANIQUES CHIRAUX
申请人:CALIFORNIA INST OF TECHN
公开号:WO2003089396A1
公开(公告)日:2003-10-30
Nonmetallic, chiral organic catalysts are used to catalyze an enantioselective aldol coupling reaction between aldehyde substrates. The reaction may be carried out with a single enolizable aldehyde, resulting in dimerization to give a β-hydroxy aldehyde, or trimerization to give a dihydroxy tetrahydropyran. The reaction may also conducted with an enolizable aldehyde and a second aldehyde, which may or may not be enolizable, so that the coupling is a cross-aldol reaction in which the a-carbon of the enolizable aldehyde adds to the carbonyl carbon of the second aldehyde in an enantioselective fashion. Reaction systems composed of at least one enolizable aldehyde, an optional additional aldehyde, and the nonmetallic chiral organic catalyst are also provided, as are methods of implementing the enantioselective aldol reaction in the synthesis of sugars.
Direct, enantioselective aldol coupling of aldehydes using chiral organic catalysts
申请人:MacMillan W.C. David
公开号:US20050197498A1
公开(公告)日:2005-09-08
Nonmetallic, chiral organic catalysts are used to catalyze an enantioselective aldol coupling reaction between aldehyde substrates. The reaction may be carried out with a single enolizable aldehyde, resulting in dimerization to give a β-hydroxy aldehyde, or trimerization to give a dihydroxy tetrahydropyran. The reaction may also conducted with an enolizable aldehyde and a second aldehyde, which may or may not be enolizable, so that the coupling is a cross-aldol reaction in which the α-carbon of the enolizable aldehyde adds to the carbonyl carbon of the second aldehyde in an enantioselective fashion. Reaction systems composed of at least one enolizable aldehyde, an optional additional aldehyde, and the nonmetallic chiral organic catalyst are also provided, as are methods of implementing the enantioselective aldol reaction in the synthesis of sugars.
Direct catalytic asymmetric cross-aldol reactions in ionic liquid media
作者:Armando Córdova
DOI:10.1016/j.tetlet.2004.03.080
日期:2004.5
Enantioselective proline-catalyzed direct asymmetric cross-aldol reactions with aldehydes were performed in ionicliquid 1-n-butyl-3-methylimidazolium hexafluorophosphate media, which simplified product isolation and catalyst recycling, affording 3-hydroxy aldehydes in high yield with excellent stereoselectivity. In addition, the enhanced reactivity of the asymmetric cross-aldol reactions in ionic