Determination of Enantiomer Purity ofβ- andγ-Amino Acids by NMR Analysis of Diastereoisomeric Palladium Complexes
摘要:
Like alpha -amino acids, beta- and gamma -amino acids form spirobicyclic complexes (see 2 and 3) by reaction with the chiral di-mu -chlorobis{2-[1-dimethylamino-xN)-ethyl]phenyl-xC}dipalladium complexes 1 under basic conditions (Scheme 1 and X-ray structures in Fig. I). The diastereoisomeric complexes formed with mixtures of enantiomers of either the amino acids or the dichloro-dipalladium complexes give rise to marked chemical-shift differences in the H-1- and C-13-NMR spectra (Figs. 2-4) to allow determination of the enantiomer purities. A simple procedure is described by which beta- and gamma -amino acids (which may be generated in situ from Boc- or Fmoc-protected precursors) are converted to the Pd complexes and subjected to NMR measurements. The effects of solvent, temperature, and variation of the aryl group in the chiral derivatizing Pd reagent are described (Figs. 4 and 5). The methyl esters of B-amino acids can also be employed, forming diastereoisomeric chloro[(amino-xN)aryl-xC][(amino-xN)alkanoate]palladium complexes 6 for determining enantiomer ratios (Scheme 6). The new method has great scope, as demonstrated for beta (2)-, beta (3), beta (2,3)-, beta (2,2,3)-, gamma (2)-, gamma (3)-, gamma (4)-, and gamma (2,3,4)- amino acid derivatives.
[EN] METHODS FOR SYNTHESIZING β-HOMOAMINO ACIDS<br/>[FR] PROCÉDÉS DE SYNTHÈSE DE β-HOMOAMINOACIDES
申请人:PROTAGONIST THERAPEUTICS INC
公开号:WO2020198682A1
公开(公告)日:2020-10-01
Methods of making β-homoamino acids as intermediate for synthesis of peptide monmer and dimer α4β7-antagonists are disclosed. The disclosed methods include solid phase and solution phase methods.
Synthesis and High-Resolution NMR Structure of a β3-Octapeptide with and without a Tether Introduced by Olefin Metathesis
作者:Marc-Olivier Ebert、James Gardiner、Steven Ballet、Andrewâ D. Abell、Dieter Seebach
DOI:10.1002/hlca.200900311
日期:2009.12
in CD3OH of the two β3‐octapeptide derivatives without (i.e., 1) and with tether (i.e., 4; Tables 1–6, and Figs. 4 and 5) provided structures of a degree of precision (by including the complete set of side chain–side chain and side chain–backbone NOEs) which is unrivaled in β‐peptide NMR‐solution‐structure determination. Comparison of the two structures (Fig. 5) reveals small differences in side‐chain
Compounds That Inhibit Replication Of Human Immunodeficiency Virus
申请人:Balzarini Maria Rene Jan
公开号:US20080076824A1
公开(公告)日:2008-03-27
The present invention relates to the discovery of a novel class of compounds that inhibit the replication of human immunodeficiency virus (HIV) and approaches to identify these compounds. More specifically, it has been found that enzymatically prepared alpha-hydroxyglycinamide and synthetically prepared alpha-hydroxyglycinamide inhibit the replication of HIV in human serum. Embodiments include methods to identify modified glycinamide compounds that inhibit HUV, methods to isolate and synthesize modified glycinamide compounds, and therapeutic compositions comprising these compounds.
The present invention provides methods of making α4β7 peptide monomer and dimer antagonists. Methods of the present invention include solid phase and solution phase methods, as well as synthesis via condensation of smaller peptide fragments. Methods of the present invention further include methods directed to the synthesis of peptides comprising one or more penicillamine residues.
β-Peptide Conjugates: Syntheses and CD and NMR Investigations of β/α-Chimeric Peptides, of a DPA-β-Decapeptide, and of a PEGylated β-Heptapeptide
作者:James Gardiner、Raveendraâ I. Mathad、Berhard Jaun、Jürgâ V. Schreiber、Oliver Flögel、Dieter Seebach
DOI:10.1002/hlca.200900325
日期:2009.12
Abstractβ3‐Peptides consisting of six, seven, and ten homologated proteinogenic amino acid residues have been attached to an α‐heptapeptide (all d‐amino acid residues; 4), to a hexaethylene glycol chain (PEGylation; 5c), and to dipicolinic acid (DPA derivative 6), respectively. The conjugation of the β‐peptides with the second component was carried out through the N‐termini in all three cases. According to NMR analysis (CD3OH solutions), the (M)‐314‐helical structure of the β‐peptidic segments was unscathed in all three chimeric compounds (Figs. 2, 4, and 5). The α‐peptidic section of the α/β‐peptide was unstructured, and so was the oligoethylene glycol chain in the PEGylated compound. Thus, neither does the appendage influence the β‐peptidic secondary structure, nor does the latter cause any order in the attached oligomers to be observed by this method of analysis. A similar conclusion may be drawn from CD spectra (Figs. 1, 3, and 5). These results bode well for the development of delivery systems involving β‐peptides.