Stereoselective synthesis of beta-substituted-L-threonines from enantiopure 5-acetyl-2-isoxazolines
| Autor: | Maddalena Gallanti, Piero Dalla Croce, Alessandra Forni, Giuseppe Cremonesi, Concetta La Rosa |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Pyrazine
Schollkopf's bislactim ether Stereochemistry beta-Hydroxy-alpha-amino acids Aldol addition on prochiral ketones Organic Chemistry Alcohol Ether Biochemistry L-Threonines Adduct chemistry.chemical_compound Hydrolysis Enantiopure drug chemistry 2-Isoxazolines Yield (chemistry) Drug Discovery Stereoselectivity |
| Zdroj: | Tetrahedron (Oxf., Print) 67 (2011): 2925–2933. doi:10.1016/j.tet.2011.02.055 info:cnr-pdr/source/autori:Cremonesi, Giuseppe; Dalla Croce, Piero; Forni, Alessandra; Gallanti, Maddalena; La Rosa, Concetta/titolo:Stereoselective synthesis of beta-substituted-L-threonines from enantiopure 5-acetyl-2-isoxazolines/doi:10.1016%2Fj.tet.2011.02.055/rivista:Tetrahedron (Oxf., Print)/anno:2011/pagina_da:2925/pagina_a:2933/intervallo_pagine:2925–2933/volume:67 |
| DOI: | 10.1016/j.tet.2011.02.055 |
| Popis: | Enantiomerically pure, 3-methyl- or 3-ethoxycarbonyl-substituted (5S)- and (5R)-5-acetyl-2-isoxazolines were obtained from the corresponding racemic mixtures by means of an enzymatic reduction with baker's yeast, followed by the separation of the enantiopure syn- and anti-alcohols and oxidation of the alcohol group. The reaction between these ketones and (2R)-Schollkopf's bislactim ether azaenolate was studied: using (55)- and (5R)-3-methyl derivatives, two diastereoisomeric adducts were obtained in good yield and stereoselectivity, whereas reaction with the (55)- and (5R)-3-ethoxycarbonyl derivatives led to a complex mixture of products. Subsequent controlled hydrolysis of the pyrazine ring led to beta-(3-methyl-4,5-dihydro-isoxazol-5-yl)-L-threonines methyl ester together with the corresponding (R)-valine dipeptides. (C) 2011 Elsevier Ltd. All rights reserved. |
| Databáze: | OpenAIRE |
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