Leucine, 3,5-dinitrobenzoyl derivatives

Leucine 3,5-dinitrobenzoyl derivs Ti-electron acceptor REGIS... 

Another type of CSP able to undergo charge transfer interaction is the one developed by Lindner s group [101], In order to determine the interactions between the quinine CSP and the enantiomeric analytes, a detailed computational study was undertaken of the interaction of this stationary phase with 3,5-dinitrobenzoyl derivatives of leucine (Figure 22-27) [102],... 

Achiral lanthanide chelates can also be added to CSAs such as arylperfluoroalkyl-carbinols, the ethyl ester of 3,5-dinitrobenzoyl-L-leucine (25) , the 3,5-dinitrobenzoyl derivative of 1-phenylethylamine, Af-(l-(l-naphthyl)ethyl)trifluoroacetamide (26) and a series of l-(l-naphthyl)ethyl urea derivatives of amino acids (27) to enhance the enantiomeric discrimination. With sulfoxide or lactone substrates , the europium ion preferentially associates with the substrate in the bulk solution. Provided the enantiomers have different association constants with the CSA, the isomer that shows the weaker association with the CSA shows the larger lanthanide-induced shifts. Low concentrations of lanthanide relative to the substrate and CSA lead to enhancements of enantiomeric discrimination in the NMR spectrum. If the concentration of lanthanide is too high, binding of the substrate to the lanthanide strips the substrate from the chiral solvating agent and diminishes the chiral discrimination in the NMR spectrum. 

Oi et al. [725] studied the retention of six amino acids (alanine, valine, leucine, methionine, phenylglycine, and phenylalanine) as their A -acetyl methyl esters and A -(3,5-dinitrobenzoyl) derivatives on an (/ )- or (iS)-l-(a-naphthyl)ethylamine stationary phase (2 = 230 nm or 254 nm). Capacity factors and a values are tabulated for all pairs of amino acid derivatives. A 40/10/1, a 100/20/1, or a 200/20/1 hexane/1,2-dichloroethane/ethanol mobile phase was used to generate the separation. 

Dinitrobenzoyl derivatives of leucine [16] and phenylglycine, and 1-(1-naphthyl) ethylurea... 

However, it was not until the beginning of 1994 that a rapid (<1.5 h) total resolution of two pairs of racemic amino acid derivatives with a CPC device was published [124]. The chiral selector was A-dodecanoyl-L-proline-3,5-dimethylanilide (1) and the system of solvents used was constituted by a mixture of heptane/ethyl acetate/methanol/water (3 1 3 1). Although the amounts of sample resolved were small (2 ml of a 10 inM solution of the amino acid derivatives), this separation demonstrated the feasibility and the potential of the technique for chiral separations. Thus, a number of publications appeared subsequently. Firstly, the same chiral selector was utilized for the resolution of 1 g of ( )-A-(3,5-dinitrobenzoyl)leucine with a modified system of solvents, where the substitution of water by an acidified solution... 

Quaternary ammonium derivative of 3,5-dinitrobenzoyl-L-leucine on ct-zirconium phosphate 175... 

Lienne et al. [170] resolved the enantiomers of albendazole sulfoxides on a column derived from the 6S )-/V-(3,5-dinitrobcnzoyl)tyrosinc chiral selector. The developed method was applied for the enantiomeric resolution of albendazole sulfoxides in plasma samples. Witherow et al. [171] immersed a commercially available thin-layer plate (thin-layer chromatography) into a solution of N-(3,5-dinitrobenzoyl)-L-leucine solution. The developed plate was used for the chiral resolution of 2,2,2-trifluoro-(9-anthryl)ethanol and l,l -binaphthol enantiomers. 

Zu, C., Brewer, B.N., Wang, B., Koscho, M.E. (2005) Tertiary amine appended derivatives of N-(3,5-dinitrobenzoyl)leucine as chiral selectors for enantiomer assays by electrospray ionization mass spectrometry. Anal. Chem., 77, 5019-5027. 

Racemic dinitropyridyl, dinitrophenyl, and dinitrobenzoyl amino acids were resolved on C-18W/UV TLC and HPTLC plates (Macherey-Nagel) developed with 2% aqueous isopropanol containing 2-5% BSA. Development times were 1-2 h, and visualization was under 254 nm UV hght. Ri differences ranged from 0.06 to 0.49 [34]. The same plates with mobile phases composed of isopropanol -E BSA-E sodium tetraborate, acetic acid, or sodium carbonate served to separate enantiomeric D,L-methylthiohydantoin andphenylthiohydantoin derivatives of amino acids, kynureyne, 3-(l-naphthyl)alanine, lactic acid derivatives, alanine and leucine p-nitroanilides, and 2,2,2-trifluoro-l-(9-anthryl)ethanol [35], and with mobile phases composed of water with 5-7% BSA -E 2% isopropanol to separate dansyl amino acid derivatives [36]. 

Wall [47] compared the chiral resolution ability of the aforementioned layers with that of plates modified with lV-(3,5-dinitrobenzoyl)-L-leucine (CS2) toward two test compounds, such as racemic 2,2,2-trifluoro-l-(9-anthryl)ethanol and l,l -bi-2-naphthol, whose optical activity derived from dissymmetry within the molecule (atropisomerism). 

For enantioseparation of selected /3-blockers, propranolol, metoprolol, and alpren-olol, amino acids such as L-arginine [16,17], L-lysine [16], L-aspartic acid [18], or derivatives of amino acids, /V-(3,5-dinitrobenzoyl)-/ -(-)-a -phenyl glycine, and A-(3,5-dinitrobenzoyl)-L-leucine were the most frequently used chiral selectors impregnated in TLC layer [19]. Tartaric acid was employed not only as a chiral selector impregnated in the layer, but also as the CMA [20]. The structures of these chiral selectors are presented in Figure 11.2. 

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