29125-25-5Relevant academic research and scientific papers
Triazolopeptides: chirospecific synthesis and cis/trans prolyl ratios of structural isomers
Paul, Andreas,Bittermann, Holger,Gmeiner, Peter
, p. 8919 - 8927 (2007/10/03)
As cis/trans prolyl isomerization plays a crucial role in various biological processes, peptide mimics capable of modifying the cis/trans Xaa-Pro ratio are of particular interest. A practical approach toward proline derived triazolopeptides employing [3+2] azide-alkyne cycloadditions as the key reaction step and the analysis of their cis/trans prolyl ratios are reported. Structural investigations indicated the adjustability of both the cis-percentage and the conformational stability toward intramolecular H-bonding effects.
Improved solid-phase peptide synthesis method utilizing alpha-azide-protected amino acids.
Lundquist 4th.,Pelletier
, p. 781 - 783 (2007/10/03)
[structure: see text]. Pure alpha-azido acids were prepared using an efficient diazo transfer method followed by buffered workup. These building blocks were used to prepare small peptides on Wang resin by two approaches. Peptides prone to diketopiperazine formation were prepared in good yields by coupling acids to resin bound iminophosphoranes during Fmoc-Wang synthesis. The iminophosphoranes can also be hydrolyzed under neutral conditions to provide unprotected amines ready for further coupling.
A practical asymmetric synthesis of homochiral α-arylglycines
Mellin-Morliere, Christelle,Aitken, David J.,Bull, Steven D.,Davies, Stephen G.,Husson, Henri-Philippe
, p. 149 - 155 (2007/10/03)
Enantioselective reduction of a series of substituted aryl trichloromethyl ketones with the CBS-catecholborane reagent afforded homochiral aryl trichloromethyl carbinols which have been elaborated to give homochiral α-arylglycines in high e.e.
Enzymatic and chiral HPLC resolution of α-azido acids and amides
Tornoe, Christian W.,Sonke, Theo,Maes, Ilse,Schoemaker, Hans E.,Meldal, Morten
, p. 1239 - 1248 (2007/10/03)
For the first time, enzymatic resolution of α-azido acid amides has been successfully demonstrated with high yields and enantiomeric excess. In one case dynamic kinetic resolution was achieved leading to more than 50% yield of the enantiomerically pure azido acid. Chiral HPLC was also used to separate racemic α-azido acids and the separation process was automated. Two routes to enantiopure α-azido acid building blocks for solid-phase peptide synthesis have, therefore, been established. Copyright (C) 2000 Elsevier Science Ltd.
The asymmetric synthesis of α-amino acids. Electrophilic azidation of chiral imide enolates, a practical approach to the synthesis of (R)- and (S)-α-azido carboxylic acids
Evans, David A.,Britton, Thomas C.,Ellman, Jonathan A.,Dorow, Roberta L.
, p. 4011 - 4030 (2007/10/02)
Two complementary approaches to the asymmetric synthesis of α-amino acids have been achieved. In the initially investigated reaction sequence, the diastereoselective bromination of the illustrated boron enolate with N-bromosuccinimide was followed by stereospecific azide displacement by tetramethylguanidinium azide. The resulting α-azido carboximides may be readily purified to high diastereomeric purity by chromatography on silica. equation presented In the second reaction sequence, the illustrated potassium enolate was treated with 2,4,6-triisopropylbenzenesulfonyl azide, and the intermediate sulfonyl triazene was decomposed through an acetic acid quench to give the α-azido carboximide. The diastereoselection of the reaction as a function of R is as follows: R = Me, CH2Ph, 97:3; R = CHMe2, 98:2; R = CMe3, >99:1; R = Ph, 91:9. The important parameters of this azidation process were evaluated, and experiments were conducted to help elucidate the mechanism of the reaction. equation presented The α-azido carboximide products have been shown to be versatile α-amino acid synthons that may be readily converted to α-amino acids as well as to N-protected α-amino acid derivatives. The racemization-free removal of the chiral auxiliary was achieved in high yield both by saponification and transesterification, either before or after reduction and acylation of the azide functionality.
ASYMMETRIC HALOGENATION OF CHIRAL IMIDE ENOLATES. A GENERAL APPROACH TO THE SYNTHESIS OF ENANTIOMERICALLY PURE α-AMINO ACIDS.
Evans, David A.,Ellman, Jon A.,Dorow, Roberta L.
, p. 1123 - 1126 (2007/10/02)
The chiral N-acyl oxazolidones 2, as the derived dibutyl boron enolates, have been demonstrated to undergo diastereoselective bromination and subsequent azide displacement to give the α-azido carboximides 4a (5 cases).These adducts may be hydrolyzed under mild conditions to the enantiomerically pure α-azido carboxylic acids 5a.
