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  • 1
    ISSN: 0899-0042
    Keywords: chiral ; chiral solvating agent ; stereochemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The N-(n-butylamide) of (S)-2-(phenylcarbamoyloxy)propionic acid, easily prepared starting from the inexpensive L-ethyl lactate, can be used as convenient chiral solvating agent (CSA) to determine the enantiomeric composition of N-(3,5-dinitrobenzoyl)amino acid methyl esters.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 376-385 
    ISSN: 0899-0042
    Keywords: circular dichroism ; detection system ; chromatography ; chiral discrimination ; enantiomeric excess ; elution order ; dissymmetry factor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A circular dichroism-based detection system presents several advantages in the HPLC analysis of chiral compounds because of the selective monitoring of optically active molecules. Its use allows reliable determination of enantiomeric excesses and elution order. To this end, the application of empirical, semiempirical, and nonempirical methods to get stereochemical information from the CD signal is reported. Furthermore, recording the CD spectra on line and evaluation of the dissymetry factor make the CD detection very powerful in characterizing the stereochemistry of chiral eluates.
    Additional Material: 10 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 580-585 
    ISSN: 0899-0042
    Keywords: asymmetric dihydroxylation ; enantiomeric excesses ; polymerization ; chiral separation ; optically active diols ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new insoluble polymer containing a Cinchona alkaloid derivative has been synthesized and used as chiral ligand in the heterogeneous enantioselective dihydroxylation of olefins. It is shown that the enantioselectivity of the optically active diols obtained from both aliphatic and aromatic substrates is always comparable to that observed in the homogeneous phase under the same reaction conditions. A method for evaluating the enantiomeric excesses of the optically active products is also described. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 113-121 
    ISSN: 0899-0042
    Keywords: 1,3,5-triazine ; chiral discrimination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Hexylamino-4-[(S)-1-(1-naphthyl)ethylamino]-6-L-valyl-L-valyl-L-valine isopropylester-1,3,5-triazine (1), a molecule characterized by two different chiral selectors, and 2-hexylamino-4,6-bis-L-valyl-L-valyl-L-valine isopropylester-1,3,5-triazine (2) and 2-ethoxy-4-hexylamino-6-[(S)-1-(1-naphthyl) ethylamino]-1,3,5-triazine (3), systems in which a single kind of chiral selector is present, have been prepared. The enantiodiscriminating ability in solution of the three compounds toward the N-3,5-dinitrobenzoyl derivatives of 1-phenylethylamine (4) or valine methylester (5) has been investigated by 1H nuclear magnetic resonance (NMR) spectroscopy: 1 shows an improved versatility, relative to 2 and 3, as a chiral solvating agent for NMR spectroscopy. On the basis of the indications obtained, the usefulness of 2-chloro-4-[(S)-1-(1-naphthyl)ethylamino]-6-L-val-L-val-L-valine isopropylester-1,3,5-triazine (1a), a direct precursor of 1, as chiral solvating agent for the determination by NMR of the enantiomeric compositions of derivatives of amines, amino alcohols, amino acids, and carboxyl acids bearing a 3,5-dinitrophenyl moiety, has been demonstrated. Chirality 9:113-121, 1997. © 1997 Wiley-Liss, Inc.
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  • 5
    ISSN: 0899-0042
    Keywords: stereoselective protein binding ; chiral HPLC ; circular dichroism ; stereoselective receptor binding ; HSA ; preparative HPLC ; atropisomeric benzodiazepine ; stereochemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chromatographic resolution of 7-chloro-1,3-dihydro-1-(1,1-dimethylethyl)-5-(2-fluorophenyl)-2H-1,4-benzodiazepin-2-on (7), the 2′-fluoro, N1-tert-butyl analogue of diazepam, was attained on both analytical and preparative (mgs) scales, by using several chiral stationary phases (CSPs). The stereochemistry of this compound was characterized by means of 1H-NMR Nuclear Overhauser Effect (NOE) analysis. The single enantiomers of 7 were tested for their configuration and stereochemical stability by circular dichroism (CD), and their interaction with the central nervous system (CNS) benzodiazepine receptor was assayed, showing a significant difference in their binding affiities. Protein binding studies with human serum albumin (HSA, the main benzodiazepine carrier in human plasma) immobilized on a silica stationary phase revealed that HSA also preferentially binds one stereoisomer of 7. However, both on line CD detection and stereospecific interaction with other common drugs clearly demonstrated that the stereoselectivity of immobilized HSA for 7 is opposite to that for all the other studied benzodiazepines. In addition, HSA stereoselectivity for 7 is opposite to CNS receptor binding stereoselectivity for the same compound. Such HSA anomalous stereoselectivity for 7 was also confirmed in aqueous buffer solution by competitive displacement studies. Compared to other chiral 1,4-benzodiazepines, compound 7 thus shows several anomalous binding properties: HSA and the CNS receptor demonstrated opposite enantioselective discrimination; HSA has reversed enantioselectivity for compound 7; and HSA stereospecifically binds the low-affinity enantiomer. Chirality 9:495-505, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 167-174 
    ISSN: 0899-0042
    Keywords: benzodiazepines ; circular dichroism ; difference spectroscopy ; human serum albumin ; stereospecific interaction ; chiral discrimination ; electronic absorption spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemistry of an achiral (Diazepam) and two chiral (3-methyl and 3-succinyloxy substituted) 1,4-benzodiazepin-2-ones interacting with human serum albumin (HSA) has been investigated by making use of difference absorption (UV) and circular dichroism (CD) spectroscopies. Evidence is obtained for a higher affinity with HSA for one of the two possible conformations of the seven-membered benzodiazepine ring. The red shift revealed by the absorption difference spectrum between the free and the bound drug accounts for the CD difference spectra observed.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 221-222 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 43-49 
    ISSN: 0899-0042
    Keywords: chiral discrimination ; enantiomeric separation ; chiral solvating agents ; asymmetric synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 9
    ISSN: 0899-0042
    Keywords: protein binding ; circular dichroism ; human serum albumin ; stereoselectivity ; drugs ; modified albumin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified albumin was prepared by selective reaction of Lys199 with acetyl salicylic acid. Protein binding investigation was carried out on native and modified proteins by difference circular dichroism (ΔCD). Acetylation of Lys199 reduces significantly the effects of the interaction between drugs in the stereoselective HSA binding at specific binding areas. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0899-0042
    Keywords: optically active aminodiols ; chiral ligands ; enantioselective reaction ; enantiomeric excess ; chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some 3-t-butyldimethylsilyloxy derivatives, synthesized from the cheap commercially available (1S,2S)-2-amino-1-phenyl-1,3-propanediol [(1S,2S)-1], have been successfully employed as new chiral ligands in the asymmetric Reformatsky reaction on aldehydic substrates. The influence both of the substrate and of the ligand on the stereochemical pathway has been investigated by varying the structure of the carbonyl substrate and of the optically active aminodiols. © 1995 Wiley-Liss, Inc.
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