29125-25-5Relevant articles and documents
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.
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.
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.
