439858-52-3Relevant academic research and scientific papers
Direct amino acid catalyzed asymmetric synthesis of polyketide sugars
Casas, Jesus,Engqvist, Magnus,Ibrahem, Ismail,Kaynak, Betul,Cordova, Armando
, p. 1343 - 1345 (2005)
Back to the future: In a biomimetic asymmetric synthesis of sugars (see scheme) sequential cross-aldol reactions of simple aldehydes were catalyzed by amino acids. Deoxysugars were obtained with excellent chemoselectivity and up to > 99% ee. This transfor
Amino acid catalyzed neogenesis of carbohydrates: A plausible ancient transformation
Cordova, Armando,Ibrahem, Ismail,Casas, Jesus,Sunden, Henrik,Engqvist, Magnus,Reyes, Efraim
, p. 4772 - 4784 (2007/10/03)
Hexose sugars play a fundamental role in vital biochemical processes and their biosynthesis is achieved through enzyme-catalyzed pathways. Herein we disclose the ability of amino acids to catalyze the asymmetric neogenesis of carbohydrates by sequential cross-aldol reactions. The amino acids mediate the asymmetric de novo synthesis of natural L- and D-hexoses and their analogues with excellent stereoselectivity in organic solvents. In some cases, the four new stereocenters are assembled with almost absolute stereocontrol. The unique feature of these results is that, when an amino acid is employed as the catalyst, a single reaction sequence can convert a protected glycol aldehyde into a hexose in one step. For example, proline and its derivatives catalyze the asymmetric neogenesis of allose with > 99% ee in one chemical manipulation. Furthermore, all amino acids tested catalyzed the asymmetric formation of natural sugars under prebiotic conditions, with alanine being the smallest catalyst. The inherent simplicity of this catalytic process suggests that a catalytic prebiotic "gluconeogenesis" may occur, in which amino acids transfer their stereochemical information to sugars. In addition, the amino acid catalyzed stereoselective sequential cross-aldol reactions were performed as a two-step procedure with different aldehydes as acceptors and nucleophiles. The employment of two different amino acids as catalysts for the iterative direct aldol reactions enabled the asymmetric synthesis of deoxysugars with > 99% ee. In addition, the direct amino acid catalyzed C2+C 2+C2 methodology is a new entry for the short, highly enantioselective de novo synthesis of carbohydrate derivatives, isotope-labeled sugars, and polyketide natural products. The one-pot asymmetric de novo syntheses of deoxy and polyketide carbohydrates involved a novel dynamic kinetic asymmetric transformation (DYKAT) mediated by an amino acid.
Direct catalytic asymmetric cross-aldol reactions in ionic liquid media
Córdova, Armando
, p. 3949 - 3952 (2007/10/03)
Enantioselective proline-catalyzed direct asymmetric cross-aldol reactions with aldehydes were performed in ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate media, which simplified product isolation and catalyst recycling, affording 3-hydrox
DIRECT, ENANTIOSELECTIVE ALDOL COUPLING OF ALDEHYDES USING CHIRAL ORGANIC CATALYSTS
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Page/Page column 22; 26-27, (2008/06/13)
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,
