Enantiomer glutamic acid

The improvements in resolution achieved in each deconvolution step are shown in Figure 3-3. While the initial library could only afford a modest separation of DNB-glutamic acid, the library with proline in position 4 also separated DNP derivatives of alanine and aspartic acid, and further improvement in both resolution and the number of separable racemates was observed for peptides with hydrophobic amino acid residues in position 3. However, the most dramatic improvement and best selectivity were found for c(Arg-Lys-Tyr-Pro-Tyr-(3-Ala) (Scheme 3-2a) with the tyrosine residue at position 5 with a resolution factor as high as 28 observed for the separation of DNP-glutamic acid enantiomers. 

Bednar P, Aturki Z, Stransky Z, Fanali S. Chiral analysis of UV nonabsorbing compounds by capillary electrophoresis using macrocyclic antibiotics Separation of aspartic and glutamic acid enantiomers. Electrophoresis 2001 22 2129-35. 

This technique was used by Reilly and Risley [21] to separate some Dansyl glutamic acid enantiomers. The separation was carried out on a 27 cm neutral capillary 50 pm I.D. The buffer was 100 mM phosphate at a pH of 6.0. The results are shown in figure 13.12. 

Wang S, Fan L, Cui S. CE-LIF chiral separation of aspartic acid and glutamic acid enantiomers using human serum... 

Crystallization Method. Such methods as mechanical separation, preferential crystallisation, and substitution crystallisation procedures are included in this category. The preferential crystallisation method is the most popular. The general procedure is to inoculate a saturated solution of the racemic mixture with a seed of the desired enantiomer. Resolutions by this method have been reported for histidine (43), glutamic acid (44), DOPA (45), threonine (46), A/-acetyl phenylalanine (47), and others. In the case of glutamic acid, the method had been used for industrial manufacture (48). 

R=Me or COOEt) failed.2-Amino-4-phosphonobutanoic acid, the phosphonic acid analogue of glutamic acid, has been obtained in resolved forms by the action of papain, followed by aniline, on 2-benzoylamino-4-(diethoxyphosphinyl)butanoic acid when anilide occurs preferentially for the L- compound. Enantiomers of 4-amino-4-phosphonobutanoic acid were obtained by resolution... 

Enders developed the hydrazone methods by choosing SAMP and its enantiomer RAMP. The application and scope of SAMP/RAMP are summarized in Figure 2-3. SAMP and RAMP can be prepared on a large scale from (S)-proline36 and (R)-glutamic acid,37 respectively. 

In this method a supersaturated aqueous solution of the racemate is inoculated with a crystal of one enantiomer of any other isomorphous crystal of a foreign substance, when this form of the isomer is precipitated. The resolution of glutamic acid by inoculation is now an industrial process. 

Recently, both enantiomers each of cis- and tran5 -5-butyl-2-heptylpyrrolidine (10c) have been synthesized from glutamic acid by an excellent method with high diastereomeric and enantiomeric purity (417). The thiolactam (293) prepared from L-glutamic acid was reacted with benzyl 2-(trifluoromethylsul-fonyloxy)oetanoate to yield the rather unstable salt (294), which without purification was treated with triphenylphosphine and A-methylpiperidine to afford... 

Stereoselective alkylation with aliphatic bromides and iodides of the Schiff bases of tert-butyl glycinate with (—)-(15,25,55)-2-hydroxypinan-3-one or (+)-(lR,2R,5R)-2-hydroxy-pinan-3-one 150 was reported to produce lipidated amino acids as d- and L-enantiomers in 80 to over 90% ee. 151 Similarly, the asymmetric synthesis of a derivative of arachidonic acid (4) has also been reported. The pure enantiomer was obtained via regioselective functionalization of a chirally pure glutamic acid. 152 ... 

The diamine (99) was prepared from (S)-proline90b) or (S)-glutamic acid I15) maintaining the asymmetric center. Racemic 2-(anilinomethyl)pyrrolidine, prepared from (RS)-5-oxopyrrolidine-2-carboxylic acid, was effectively resolved into a pair of enantiomers by fractional crystallization of its mandelic acid salt U6). Moreover, the preferential crystallization of its 4-hydrobenzoic acid salt was found to produce both enantiomers in high optical purities by alternate seeding116). 

The direction of enantio-differentiation (the predominant enantiomer R or S, to be produced) is decided by two factors. One factor is the configuration of the chiral structure, that is, if the catalyst modified with (S)-glutamic acid [(S)-Glu-MRNi] produces (R)-MHB from MAA, then (R)-Glu-MRNi produces (S)-MHB (2). The other factor is the nature of X. That is, when the amino acid or hydroxy acid with the same configuration is used as the modifying reagent, the configurations of the predominant products are enantiomers of each other in most cases. For example, (S)-aspartic acid-MRNi produces (R)-MHB and (S)-malic acid-MRNi produces (S)-MHB (19). 

The (R)-enantiomer of (242) has also been prepared and used as a chiral auxiliary in an enantioselective aldol synthesis of (+)-(S )-gingerol (79CB3703). (R )-Glutamic acid (246) was thus converted into (i )-pyroglutamic acid by simply heating in water. Conversion of (247) to its methyl ester and LAH reduction delivered alcohol (248). Ethyl nitrite treatment of (248) gave nitrosoamine (249), which was methylated to furnish (250). Exposure of (250) to LAH completed the synthesis of the required chiral auxiliary RAMP [(R)- l-amino-2-(methoxymethyl)pyrrolidine]. The hydrazone (252), derived from RAMP and acetone, was... 

Some of the less common d enantiomers of amino acids are also found in nature. For example, D-glutamic acid is found in the cell walls of many bacteria, and D-serine is found in earthworms. Some naturally occurring amino acids are not a-amino acids y-Aminobutyric acid (GABA) is one of the neurotransmitters in the brain, and jS-alanine is a constituent of the vitamin pantothenic acid. 

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