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  • Organic Chemistry  (4,530)
  • Inorganic Chemistry  (3,613)
  • Deutschland
  • 1990-1994  (8,144)
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Keywords
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Year
  • 1
    Electronic Resource
    Electronic Resource
    The fatty acid composition of subcutaneous fat in German adults (1992)
    Springer
    European journal of nutrition 31 (1992), S. 130-137 
    Details
    ISSN: 1436-6215
    Keywords: fattyacids ; subcutaneousfat ; nutrition ; trans fattyacids ; atherosclerosis ; Germany ; Fettsäuren ; subkutanes Fettgewebe ; Ernährung ; trans-Fettsäuren ; Atherosklerose ; Deutschland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung In der vorliegenden Studie wurde die Fettsäurenkomposition des subkutanen Fettgewebes (SCF) von 47 deutschen Erwachsenen analysiert. Es zeigte sich kein Zusammenhang zwischen dem Alter bzw. Geschlecht der Probanden und dem Fettsäurenstatus. Monoene bildeten den Hauptanteil der Fettsäuren (FA) im SCF. Linolsäure war die wichtigste mehrfach ungesättigte Fettsäure. Linolsäuremetaboliten wurden nur in geringen Mengen gefunden. Im Vergleich zu den Ergebnissen von Studien in den USA und den Niederlanden ist die FA-Zusammensetzung des SCF bei deutschen Probanden durch geringere Anteile von Linolsäure und höhere Anteile von Palmitinsäure gekennzeichnet. Der Gehalt an trans-FA entspricht dem, der bei Frauen in den Niederlanden gefunden wurde, er ist jedoch deutlich niedriger als bei amerikanischen Männern. In der Beurteilung der Unterschiede in der Fettsäurenkomposition des SCF in verschiedenen Ländern sollte jedoch berücksichtigt werden, daß die Anteile der wichtigsten FA in allen untersuchten Populationen eine große interindividuelle Schwankungsbreite zeigten.
    Notes: Summary The fatty acid (FA) composition of subcutaneous fat (SCF) was analyzed in 47 German adults. No influences of sex or age on the FA status of the probands could be detected. SCF consisted mainly of monoenoic fatty acids. Linoleic acid was the major polyunsaturated fatty acid. Linoleic acid metabolites were found in small quantities only. In comparison to the results of studies in the USA and the Netherlands the FA composition of SCF in German probands was characterized by lower levels of linoleic acid and higher contents of palmitic acid. The trans-FA content was similar to that in Dutch women, but lower than in American male probands. However, in evaluating the differences in the FA composition of SCF in different countries, it has to be noted that there are wide ranges in the proportions of the major FA in all populations studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623071
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  • 2
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020101
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  • 3
    Electronic Resource
    Electronic Resource
    Metabolism of halazepam by rat liver microsomes: Stereoselective formation and n-dealkylation of 3-hydroxyhalazepam (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 1-9 
    Details
    ISSN: 0899-0042
    Keywords: halazepam ; 3-hydroxyhalazepam ; diazepam ; N-desmethyldiazepam ; oxazepam ; enantiomers ; rat liver microsomes ; stereoselectivity ; enantioselectivity ; hydroxylation ; enantioselective N-dealkylation ; kinetics of racemization ; circular dichroism spectra ; chiral stationary phase ; high-performance liquid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolism of halazepam [7-chloro-1,3-dihydro-5-phenyl-1-(2,2,2-trifluoroethyl)-2H-1,4-benzodi epin-2-one, HZ] was studied by incubation with liver microsomes prepared from untreated, phenobarbital (PB)-treated, and 3-methylcholanthrene (3MC)-treated male Sprague-Dawley rats. Metabolites of HZ were separated by normal-phase HPLC. Relative rates of HZ metabolism by liver microsomes prepared from untreated and treated rats were PB-treated ≫ untreated 〉 3MC-treated at low concentration of microsomal enzymes (0.25 mg protein per ml of incubation mixture) and PB-treated ≫ 3MC-treated ≈ untreated at high concentration of microsomal enzymes (2 mg protein per ml of incubation mixture). The relative amounts of major metabolites were found to be 3-hydroxy-HZ (3-OH-HZ) 〉 N-desalkylhalazepam (NDZ, also known as N-desmethyldiazepam and nordiazepam) ≫ oxazepam (OX) for all three rat liver microsomal preparations and the distribution of metabolites was independent of microsomal enzyme concentrations. Enantiomers of 3-OH-HZ were resolved by HPLC on a Chiralcel OC column (cellulose trisphenylcarbamate coated on silica gel, particle size 10 μm). 3-OH-HZ enantiomeres have racemization half-lives of ∼ 150 min in pH 4,7.5, and 10 aqueous solutions. 3-OH-HZ formed in the metabolism of HZ by liver microsomes prepared from untreated and treated rats were found to have 3R/3S enantiomer rations of 37/63 (untreated), 55/45 (PB-treated), and 36/64 (3MC-treated), respectively. N-dealkylation of 3-OH-HZ by liver microsomes from PB-treated rats was substrate enantioselective; the 3R-enantiomer was N-dealkylated faster than 3S-enantiomer. The results indicated that the stereoselective C3-hydroxylation of HZ is dependent on the cytochromes P-450 present in the rat liver microsomal preparations; pro-R in liver microsomes from PB-treated rats and pro-S in liver microsomes from untreated and 3MC-treated rats, respectively.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020102
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  • 4
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020201
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  • 5
    Electronic Resource
    Electronic Resource
    Stereoselective arylpropionyl-CoA thioester formation in vitro (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 67-73 
    Details
    ISSN: 0899-0042
    Keywords: arylpropionic acid ; coenzyme A thioester ; inversion ; ibuprofen ; fenoprofen ; flurbiprofen ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The inversion from R- to S-enantiomer that occurs for some arylpropionic acids may have both toxicological and therapeutic implications. To characterize some properties of this inversion, arylpropionyl-CoA thioester formation was studied in rat tissue homogenates and subcellular fractions for the enantiomers of fenoprofen, ibuprofen, and flurbiprofen. Thioesters were formed from (R)-fenoprofen (64%) and (R)-ibuprofen (33%) but not from the corresponding S-enantiomers or the enantiomers of flurbiprofen. This correlates with the extensive inversion of fenoprofen and ibuprofen and lack of inversion of flurbiprofen in vivo. Subcellular fractions from rat liver showed thioester formation to occur in mitochondria and microsomes but not cytosol. Once formed, the thioesters were readily racemized by whole rat liver homogenate, mitochondria, and cytosol, but only partially inverted (S:R = 0.3) in microsomes. Thioester formation from fenoprofen and ibuprofen was studied in tissue homogenate obtained from liver, diaphragm, kidney, lung, skeletal muscle, smooth muscle, fat, caecum, and intestines. The liver was at least 50-fold more efficient than the other tissues studied and would be expected to be a major organ of enantiomeric inversion. Our data support the hypothesis that R- to S-enantiomeric inversion of arylpropionic acids proceeds via the stereoselective formation of CoA thioesters followed by enzymatic racemization and hydrolysis of the thioesters to regenerate free acid.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020202
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical synthesis, absolute configuration, and stereochemistry of formation of 10-hydroxywarfarin: A major oxidative metabolite of (+)-(r)-warfarin from hepatic microsomal preparations (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 96-105 
    Details
    ISSN: 0899-0042
    Keywords: human liver ; P-450IIIA family ; 10-hydroxywarfarin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a diastereomerically pure 10-hydroxywarfarin [4-hydroxy-3-(2-hydroxy-3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one] was accomplished in three steps from racemic warfarin. The relative configuration of the synthetic product was established by conversion to a cyclic derivative followed by NMR and X-ray diffraction analysis. Absolute stereochemistry was determined by enzymatic conversion of either of the pure enantiomers of warfarin to a 10-hydroxy metabolite of known relative configuration. Metabolic formation of 10-hydroxywarfarin was studied using hepatic microsomal preparations from female rats and man. The formation of 10-hydroxywarfarin catalyzed by hepatic microsomes from both dexamethasone-treated rats and man was highly stereoselective [(R)/(S): 3.4-9.0] for (R)-warfarin. In contrast, little stereoselectivity was observed in reactions catalyzed by untreated rat liver microsomes. The resultant stereochemistry at the site of oxidation was also found to be highly dependent on substrate stereochemistry. (R)-Warfarin gave (9R;10S)-10-hydroxywarfarin with only a trace of the (9R;10R) isomer irrespective of which enzyme preparation was used for catalysis, while (S)-warfarin gave (9S;10R)-10-hydroxywarfarin with only a trace of the (9S;10S) isomer, again irrespective of which enzyme preparation was used for catalysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020207
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  • 7
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 128-128 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020211
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  • 8
    Electronic Resource
    Electronic Resource
    Racemates versus enantiomers in drug development: Dogmatism or pragmatism? (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 129-133 
    Details
    ISSN: 0899-0042
    Keywords: chiral drugs ; racemates ; eutomers ; distomers ; pharmacodynamic enantioselectivity ; pharmacokinetic enantioselectivity ; enantioselective interactions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020302
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  • 9
    Electronic Resource
    Electronic Resource
    Enantioselective aliphatic hydroxylations of racemic 1-hydroxy-3-methylcholanthrene by rat liver microsomes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 141-149 
    Details
    ISSN: 0899-0042
    Keywords: 3-methylcholanthrene ; 1-hydroxy-3-methylcholanthrene ; 1-hydroxy-3-hydroxymethylcholanthrene ; 3-methylcholanthrene trans-1,2-diol ; 3-methylcholanthrene cis-1,2-diol ; high-performance liquid chromatography ; chiral stationary phase ; resolution of enantiomers ; absolute configuration ; circular dichroism spectra ; enantioselective hydroxylation ; rat liver microsomes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomeric pairs of 1-hydroxy-3-hydroxymethylcholanthrene (1-OH-3-OHMC), 3-methylcholanthrene (3MC) trans- and cis-1,2-diols, and 1-hydroxy-3-methylcholanthrene (1-OH-3MC) were resolved by HPLC using a covalently bonded (R)-N-(3,5-dinitrobenzoyl)phenylglycine chiral stationary phase (Pirkle type 1A) column. The absolute configuration of an enantiomeric 3MC trans-1,2-diol was established by the exciton chirality CD method following conversion to a bis-p-N,N-dimethylaminobenzoate. Incubation of an enantiomeric 1-OH-3MC with rat liver microsomes resulted in the formation of enantiomeric 3MC trans- and cis-1,2-diols; the absolute configurations of the enantiomeric 1-OH-3MC and 3MC cis-1,2-diol were established on the basis of the absolute configuration of an enantiomeric 3MC trans-1,2-diol. Absolute configurations of enantiomeric 1-OH-3-OHMC were determined by comparing their CD spectra with those of enantiomeric 1-OH-3MC. The relative amount of three aliphatic hydroxylation products formed by rat liver microsomal metabolism of racemic 1-OH-3MC was 1-OH-3-OHMC 〉 3MC cis-1,2-diol 〉 3MC trans-1,2-diol. Enzymatic hydroxylation at C2 of racemic 1-OH-3MC was enantioselective toward the 1S-enantiomer over the 1R-enantiomer (∼3/1); hydroxylation at the C3-methyl group was enantioselective toward the 1R-enantiomer over the 1S-enantiomer (∼58/42). Rat liver microsomal C2-hydroxylation of racemic 1-OH-3MC resulted in a 3MC trans-1,2-diol with a (1S,2S)/(1R,2R) ratio of 63/37 and a 3MC cis-1,2-diol with a (1S,2R)/(1R,2S) ratio of 12/88, respectively.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020304
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of the absolute configuration and enantiomeric purity of alcohols from the 13C-NMR spectra of the corresponding MTPA esters (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 175-184 
    Details
    ISSN: 0899-0042
    Keywords: cyclohexanols ; sterols ; Dale-Mosher model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From a study of the 13C-shift values of the MTPA esters of 3-substituted cyclohexanols of known absolute configuration an empirical rule has been developed to determine the absolute configuration of chiral cyclohexanols. The method is based on the Dale-Mosher model, which was originally developed for 1H-NMR spectra. The scope and limitations of this method are discussed. The enantiomeric purity of the alcohols can be determined simultaneously by integration of the signals in well-resolved diastereotopic carbon pairs.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020309
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  • 11
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 205-205 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020314
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  • 12
    Electronic Resource
    Electronic Resource
    Enantiomeric resolution of DNS-amino acids by ligand exchange chromatography using l-phenylalaninamide together with Cu(II) ions as chiral additives to the eluent (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 194-199 
    Details
    ISSN: 0899-0042
    Keywords: chiral recognition ; copper(II) complexes ; high-performance liquid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resolution of various α-DNS DL-amino acids by ligand exchange chromatography of L-phenylalaninamide-copper(II) complexes on a conventional reversed-phase packing is reported. Parameters of the mobile phase which control retention and enantioselectivity such as concentration of Cu(II) ion and L phenylalaninamide (PheNH2), pH, ionic strength, and acetonitrile content were examined. In order to obtain further information on the distribution and stability of the prevailing complex species formed between the metal ion and the chiral selector, spectrophotometric measurements in different media were also carried out.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020312
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  • 13
    Electronic Resource
    Electronic Resource
    A vivid model illustrating chiral recognition induced by achiral structures (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 208-210 
    Details
    ISSN: 0899-0042
    Keywords: enantioselectivity ; three-point model ; didactic model ; chiral separations ; ligand-exchange chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If diastereomeric complexes are adsorbed on a surface or if they include a molecule of solvent, two points of attractive interaction between the chiral species of the complex can be sufficient for mutual chiral recognition of these species. In special cases even one single point of interaction is sufficient. This extension of the three-point contact rule of Dalgliesh, first observed in chiral ligand-exchange chromatogrphy, can be demonstrated by using hands.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020403
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  • 14
    Electronic Resource
    Electronic Resource
    Quantitation of the criticality of chiral centers toward stereoselective recognition: Epimeric eudismic analysis of 1,3-oxathiolane muscarinic agonists and antagonists (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 211-218 
    Details
    ISSN: 0899-0042
    Keywords: stereoselectivity ; quantitative stereo-structure-activity relationships ; muscarinic receptor ; enantiomeric and epimeric ligands ; criticality of chiral centers ; substructure affinity contributions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently published data1 on the aftinities of 14 pairs of chiral ligands, (1,3-oxathiolanes) for muscarinic receptors in three different tissues were subjected to eudismic analysesThe enantiomeric eudismic-affinity correlations (EACs) found by Gualtieri et al.1 were confirmed and extended to the submolecular level: (1) regressions of the eudismic index (log affinity ratio; EI) against eutomer potency of the average affinities were highly significant, indicating that the binding sites in all three tissues are identical; (2) for the five agonists the EAC was shifted to lower affinities and had a small slope (EAQ), in agreement with previous observations in other systems; (3) of the nine antagonists, six gave an excellent regression with unit slope, practically superimposable on that previously obtained for 10 structurally different oxotremorine derivatives, while two others (1,3-oxathiolanes) could be plotted on a separate line with the same EAQ, but shifted to higher affinities; (4) the aberrant low EI of the last antagonist could be explained in terms of its structureFurthermore, an epimeric EAC (EEAC) revealed additional important information for quantitative stereo-structure-activity relationships (QSSAR): the 25 possible epimeric comparisons were found to group into 6 different EACs in accord with differences in their structure: (1) the agonists fell on three separate lines of nearly identical (unitary) slope, which grouped cleanly in terms of the center of epimerization (positions 2, 3, and 5); (2) the antagonists of lower affinity fell on three lines with a common X-intercept but with different slopes corresponding to epimerization at the different centers of chirality, indicating that these display quantitative differences in their criticality toward stereoselective recognition; (3) the remaining two antagonists of higher affinity fell on a separate line, again of unit slope.The significance of these correlations is discussed in relation to receptor speciation and in regard to other stereoselectivity data available on muscarinic receptorsThe quantitation of the criticality of different chiral centers, made possible here by the very high binding energies involved, should also be applicable to other stereoselective recognition processes (e.g., in enantioselective chromatography). Finally, a fundamental assumption of molecular pharmacology and QSAR, i.e., that a given structural feature always contributes a constant amount to the overall binding energy, is questioned in view of the above findings, which indicate that the contribution increases with the overall affinity, a feature which might be applicable to all pharmaca, not just to those containing chiral molecules.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020404
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  • 15
    Electronic Resource
    Electronic Resource
    (R)- and (S)-5-hydroxy-2-(dipropylamino)tetralin (5-OH DPAT): Assessment of optical purities and dopaminergic activities (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 90-95 
    Details
    ISSN: 0899-0042
    Keywords: stereoselectivity ; 5-OH DPAT ; dopamine D2-receptor antagonist ; chiral ion pair chromatography ; N-benzyloxycarbonylglycyl-L-proline (L-ZGP) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic 5-hydroxy-2-(dipropylamino)tetralin (5-OH DPAT), a potent and selective dopamine (DA) D2-receptor agonist, was resolved into the enantiomers by a new method. The enantiomers of 5-OH DPAT were determined by chiral ion-pair chromatography using N-benzyloxycarbonylglycyl-L-proline as the counter ion. The enantiomeric purity of (R)-5-OH DPAT was found to be 〉 99.7%. The ability of the enantiomers to change the rat brain DOPA levels was evaluated in vivo. The results indicate that (R)-5-OH DPAT is a weakly potent DA D2-receptor antagonist.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020206
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  • 16
    Electronic Resource
    Electronic Resource
    An HPLC procedure for the enantiomeric purity of an optically active cytosine analogue using ligand exchange (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 275-279 
    Details
    ISSN: 0899-0042
    Keywords: nucleotide analogue ; antiviral ; chiral separation ; complexation ; ion-pairing ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An acylonucleotide analogue, 1-[3-hydroxy-2-(phosphonyl-methoxy)propyl]cytosine (HPMPC), has shown activity against herpes simplex Type I and Type II viruses. An HPLC separation of the R- and S-enantiomers of HPMPC by ligand exchange using a mobile phase containing phenylalanine as the chiral modifier and copper(II) as the metal ion is reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020414
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  • 17
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 288-288 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020416
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  • 18
    Electronic Resource
    Electronic Resource
    Excavations in drug chirality: 1. Cyclothiazide (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 2-13 
    Details
    ISSN: 0899-0042
    Keywords: drug stereochemistry ; cyclothiazide ; stereoisomerism ; chiral HPLC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: There is a great deal of current interest in the role and importance of chirality in the development of new drugs, but little attention is being paid to the stereochemistry of older drugs. Indeed, many older chiral drugs were introduced without adequate information on their stereochemical identity or composition. We have examined one such drug, the antihypertensive diuretic agent cyclothiazide. Standard sources of drug information and the research literature do not provide data on the stereochemical composition of clinically used cyclothiazide, although scattered reports indicate that the drug may consist of “several stereoisomers.” Inspection of the chemical structure of the drug, 6-chloro-3,4-dihydro-3-(5-norbornen-2-yl)-2H-l,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide, shows that it can exist as eight stereoisomers that may form four racemates. Using synthesis, fast-atom-bombardment mass spectrometry, gas-liquid chromatography, chiral and nonchiral high-performance liquid chromatography, and nuclear magnetic resonance spectroscopy, we determined that pharmaceutical cyclothiazide is in fact a mixture of the eight stereoisomers in the form of the four racemates. The two racemates with endo configuration at the norbornene moiety predominate over the exo racemates, and small but significant differences in isomer distribution between different batches of the drug were observed. We urge that in studies of older drugs the stereochemical details be considered.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030103
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  • 19
    Electronic Resource
    Electronic Resource
    Interaction of propafenone enantiomers with human α1-acid glycoprotein (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 30-34 
    Details
    ISSN: 0899-0042
    Keywords: propafenone ; enantiomers ; α1-acid glycoprotein ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of propafenone enantiomers with human α1-acid glycoprotein was studied using high-performance liquid chromatography. Each of the two optical antipodes interacted with one class of high-affinity binding sites characterized by Ka(R) = (6.18 ± 0.93) × 105 M-1, n(R) = 1.34 ± 0.09 for the (R)-isomer and Ka(S) = (8.93 ± 1.82) × 105 M-1, n(S) = 0.99 ± 0.08 for the (S)-isomer. Nonspecific binding to secondary low-affinity high-capacity binding site(s) was only slightly greater in the case of the (S)-enantiomer (n′k′(S) = (1.06 ± 0.09) × 104 M-1) compared to the (R)-enantiomer (n′k′(R) = (6.87 ± 0.72) × 103 M-1). It was concluded that both enantiomers interact with common single class of high-affinity binding sites on AAG (along with nonspecific binding) exhibiting only slight stereoselectivity for propafenone.
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    Direct measurement of enantiomeric ratios of enzymatic resolution by chiral high-performance liquid chromatography (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 67-70 
    Details
    ISSN: 0899-0042
    Keywords: enzymatic resolution ; chiral HPLC ; enantiomeric ratio ; enantiomeric excess ; 2-(phenoxy)propionate ; 2-(4-chlorophenoxy)propionate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R)- and (S)-Methyl 2-(phenoxy)propionate and their acids could be separated simultaneously by a Chiralcel OD or OK column, while (R)- and (S)-methyl 2-(4-chlorophenoxy)propionate and their acids were separated concurrently only by an OK column. This is a novel and facile way to measure the enantiomeric excesses of the remaining substrate and product in the reaction of enzymatic resolution; enantiomeric ratios could then be calculated.
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    Announcements (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 88-89 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030115
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    Enantiomeric resolution of DNS-amino acids by ligand exchange chromatography: Comparison of different chiral amino acid amides as additives to the mobile phase (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 190-193 
    Details
    ISSN: 0899-0042
    Keywords: HPLC ; bis(L-amino acid amidato)-copper(II) complexes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study developing enantiomeric separations by metal chelate additives to the mobile phase in reversed-phase liquid chromatography is reported. In particular the use of Cu(II) complexes of L-prolinamide (L-ProNH2) and L-valinamide (L-ValNH2) is examined and discussed. Interestingly, for a series of DNS-amino acids these selectors show higher enantioselectivity than that obtained with the corresponding nonderivatized amino acid-Cu(II) complexes.
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020401
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    Studies on the stereoselective effects of a novel 5-HT2 receptor antagonist on contractile responses of rat aorta (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 226-228 
    Details
    ISSN: 0899-0042
    Keywords: optical isomers ; enantiomers ; vascular smooth muscle ; 5-hydroxytryptamine ; noradrenaline ; potassium ; calcium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of the enantiomers of a novel 5-HT2 receptor antagonist, (±)-(1R,3S)-1-[2-[4-[3-(p-fluorophenyl)-1-indanyl]-piperazinyl]ethyl]-2-imidazolidinone, was studied on serotonin (5-HT), noradrenaline (NA), potassium (K+), and calcium (Ca2+)-induced contractions in isolated rat thoracic aorta. The enantiomers shifted the 5-HT, NA, K+, and Ca2+ concentration-response curves to the right in a concentration-dependent manner and depressed the maximal contractile responses. The (+)-enantiomer was a far more potent inhibitor of 5-HT-induced contractions than the (-)-enantiomer. The (+)-enantiomer and phentolamine, both at 10-6 M, had equal inhibitory effects on NA-evoked contractions. The (+)-enantiomer was again more potent in inhibiting NA-induced contractions than the (-)-enantiomer. Both enantiomers had an equieffective inhibitory effect on K+ and Ca2+-induced contractions. The results show that the 5-HT and α-adrenoceptor antagonism of the two enantiomers is stereoselective, the (+)-enantiomer being more potent than the (-)-enantiomer. In contrast the enantiomers had equal, nonstereoselective inhibitory effects on K+ and Ca2+-evoked contractions.
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    Calmodulin discriminates between the two enantiomers of the receptor-operated calcium channel blocker sk&f 96365: A study using 1H-NMR and chiral HPLC (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 229-232 
    Details
    ISSN: 0899-0042
    Keywords: receptor-operated calcium channel antagonist ; 1H NMR ; chiral HPLC ; calmodulin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H nuclear magnetic resonance at 360 MHz shows that SK&F 96365 (1-{β-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl}-1H- imidazole hydrochloride), an antagonist of mammalian receptor-operated calcium channels, interacts with the calcium-binding regulatory protein calmodulin (CaM). This may be inferred by a number of chemical shift changes in the spectrum of the calcium-saturated protein induced by addition of the compound. Moreover, two well-resolved singlets corresponding to the 2-proton of the SK&F 96365 imidazolium moiety are observed in the spectrum over a wide range of protein:compound ratios. Separation of rac SK&F 96365 into its two enantiomers by high-performance liquid chromatography on a cellulose tris (4-methylbenzoate) column enabled us to show that the doubling of this NMR signal in the presence of CaM is due to a propensity of the protein to distinguish between the two optical isomers of the compound.
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    Second international symposium on Chiral discrimination (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 157-157 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030215
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    Synthesis of the [8] gingerol enantiomers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 151-155 
    Details
    ISSN: 0899-0042
    Keywords: (-)-(R) and (+)-(S) [8] gingerol ; enantiomers synthesis ; chiral stationary phase ; HPLC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-(S)-5-Hydroxy-1-(4-hydroxy-3-methoxyphenyl)-3-dodecanone 1a commonly named (+)-(S)-[8] gingerol is a natural product known to have cardiotonic activity.1-5 A total synthesis of both enantiomers is described with details for the first time using a general synthetic scheme which was recently outlined in the literature.6 This synthesis relies both on the separation of the diastereoisomers 4a and 4b by simple column chromatography on silica gel and on an HPLC analysis on a chiral phase to determine the optical purity of the enantiomers 8a and 8b of protected [8] gingerol. The gingerol isomers were thus obtained in good chemical yields in greater than 96% enantiomeric excess.
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    Masthead (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030301
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    Drug chirality: Impact on pharmaceutical regulation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 161-164 
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    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030303
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    Molecular graphic and modelling training course intensive four-day course with “hands-on” training (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 158-158 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030216
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    N-(n-Butylamide) of (S)-2-(phenylcarbamoyloxy)propionic acid: A new chiral solvating agent, derived from L-lactic acid, for the enantiomeric purity determination of derivatized amino acids (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 174-176 
    Details
    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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    New chiral fluoroanthryl derivatives: Resolution of the enantiomers by chromatography on cellulose esters and their evaluation as chiral solvating agents in NMR spectroscopy (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 177-182 
    Details
    ISSN: 0899-0042
    Keywords: cellulose triacetate ; tribenzoylcellulose ; methylbenzoylcellulose ; chiral phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,2,2-Trifluoro-1-(9-anthryl)ethanol (TFAE) has now been widely used as a powerful chiral solvating agent for NMR spectroscopy. In connection with the development of a new general synthesis of halogenoalkylalkanols, starting from the corresponding ketone or aldehyde, we synthesized some halogenoalkyl-1-(9-anthryl)methanol derivatives liable to work as chiral solvating agents. The racemic anthryl derivatives were preparatively resolved into their corresponding enantiomers by chromatography on triacetyl cellulose (CTA I) or on meta-methylbenzoyl cellulose beads as chiral stationary phases. Their effectiveness as chiral solvating agents was measured as the magnitude of the splitting induced in the 1H-NMR spectra of 1-phenylethylamine and of (1-phenylethyl)methyl ether in comparison with splitting caused by TFAE. While TFAE induced the largest splitting for 1-phenylethylamine, 2,2,3,3,3-pentafluoro-1-(9-anthryl)propanol 2 was more effective in the case of (1-phenylethyl)methyl ether, pointing out that depending on the substrate, other derivatives of the TFAE type can be very useful as chiral solvating agents.
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    Direct chromatographic resolution of racemic cyclohexylaminoglutethimide and its acetylated metabolite using cellulose-based chiral stationary phase (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 204-207 
    Details
    ISSN: 0899-0042
    Keywords: chiral chromatography ; cellulose-based chiral stationary phase ; aromatase inhibitor ; cyclohexylaminoglutethimide and metabolite ; enantiomeric separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic cyclohexylaminoglutethimide (±ChAG) and its acetylated metabolite (±ChAG) were resolved by a direct chromatographic method using a Chiracel OD column without derivatization. Maximum resolutions (R) of 4.89 and 0.74 were obtained for the enantiomers of cyclohexylaminoglutethimide and its acetylated metabolite, respectively.
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    Masthead (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030401
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    Solid angle as steric parameter of acyclic saturated groups (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 242-253 
    Details
    ISSN: 0899-0042
    Keywords: steric effects ; geometric model ; ester hydrolysis ; ester conformation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the early aim of quantifying steric consequences of chirality, efforts to define a nonempirical steric parameter of chemical groups are reported. Steric hindrance of a reacting center by any acyclic saturated R group has been characterized by a geometric “axial steric parameter”: the solid angle of R. When the group is a “symmetric top substituent” (i.e., when all the terminal atoms are equivalent), the solid angle matches the solid angle of a cone envelope of R. The definition of this cone is compared with Tolman's definition of a ligand cone in organometallic complexes. The chemical significance of this parameter is shown by an excellent correlation with the Dubois' experimental steric parameter E′s. Modeling steric repulsion by the cone of R, and correcting solid angles for conformational effects, only 3 empirical coefficients are needed to calculate 33 values of E′s with less than 10% error. The cone model is suggested to be relevant within the limits of random and independent free rotations about all the bonds in the C-R group. A separation between “axial cone steric hindrance” and other steric effects is proposed. The basic model and the corrections proposed allow the conformational features of esters to be discussed.
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    Absolute configuration of feroxidin: An experimental support to snatzke's helicity rules for tetralins (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 263-267 
    Details
    ISSN: 0899-0042
    Keywords: aloe ; feroxidin ; absolute configuration ; tetralins ; helicity ; Cotton effect ; conformation ; half-chair cyclohexene ring ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configuration of carbon-8 in feroxidin (1) was proven to be (S) by chemical correlation with (S)-methylsuccinic acid. Previous demonstration that 6-hydroxy and 8-methyl groups are equatorial and pseudoaxial, respectively, in a half-chair conformation of the cyclohexene ring (relative configuration) allowed the absolute stereochemistry of the whole molecule to be established (Fig. 3). The CD spectrum of feroxidin represents the first experimental test confirming the applicability of Snatzke's helicity rules to tetralins m-disubstituted on the aromatic ring.
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    Cooperation in a deep helical energy well (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 285-291 
    Details
    ISSN: 0899-0042
    Keywords: macromolecular ; optical activity ; polyisocyanate ; deuterium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to random coil polymers, polyisocyanates maintain a highly extended helical conformation in solution. This structural characteristic causes unusually large chiral optical properties to arise from copolymerization of tiny proportions of optically active monomer isocyanates with achiral isocyanates or even from stereospecific placement of deuterium in the side chain of poly(n-hexyl isocyanate). These effects can be understood as phenomenologically related to the optical activity amplification properties of vinyl polymers studied by Pino and his co-workers and ascribed to breaking the energetic degeneracy of the otherwise equally populated left- and right-handed helical states of the backbone. Statistical thermodynamic calculations, based on this model, and analogous to those carried out earlier on the vinyl polymers, allow matching the temperature and molecular weight dependence of the optical activity in poly((R)-1-deuterio-1-hexyl isocyanate) to the approximate responsible energy terms.
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    An alternative to Urry's model for the gramicidin transmembrane channels (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 315-317 
    Details
    ISSN: 0899-0042
    Keywords: ↕ β6.3-model ; ↕ β-model ; ↕ β7.2-structures ; closed structures ; open structures ; non-conducting dimers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is suggested that the conducting transmembrane channels formed by the linear gramicidins A, B and C may be head-to-head (formyl end-to-formyl end) dimers of double-stranded parallel β-helices. This possibility is not in conflict with any of the various experimental findings bearing on the molecular organization of the channels and represents a plausible alternative to Urry's model of a head-to-head dimer of single-stranded β6.3-helices.
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    Editorial (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 1-1 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530030102
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    Enantiomers of 11-hydroxy-10-methylaporphine having opposing pharmacological effects at 5-HT1A receptors (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 19-23 
    Details
    ISSN: 0899-0042
    Keywords: aporphine enantiomers ; serotonin 5-HT1A receptors ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two enantiomers of the title compound have been prepared by different synthetic routes. Both bind strongly to 5-HT1A receptors from rat forebrain membrane tissue. However, in a guinea pig ileum preparation, the (R)-enantiomer exhibits properties consistent with its being an agonist, whereas the (S)-enantiomer shows no agonist effect, but it blocks the actions of the (R)-enantiomer and of 8-hydroxy-2-di-n-propylaminotetralin (8-OH-DPAT), a 5-HT1A agonist. These data are presented as a rare example of enantiomers which demonstrate opposite pharmacological effects at the same receptor.
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    Enantioselective carbonylation reactions of para-substituted 2-phenylpropenes (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 341-344 
    Details
    ISSN: 0899-0042
    Keywords: enantioselectivity ; carbonylation ; hydroformylation ; hydroalkoxycarbonylation ; para-substitution ; 2-phenylpropene ; platinum catalyst ; palladium catalyst ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective hydroformylation catalyzed by [(R,R)-Diop]Pt(SnCl3)Cl7 and the enantioselective hydroisopropoxycarbonylation catalyzed by [(R,R)-Diop]PdCl28 or by [(R,R)-Diop-dbp]PdCl29 of some para-substituted 2-phenylpropenes (para substituents = NO2, H, CH3O, Cl, CF3) was investigated in order to recognize possible electronic influences on the regioselectivity and on the enantioface selection which take place in such carbonylation reactions. The catalytic systems used gave no carbonylation products when the nitro compound was the substrate. 7 and 8 show similar regioselectivities, the less branched isomer being exclusively formed for all substrates except p-methoxy-2-phenylpropene which gave small amounts of the alternative regioisomer. The enantioselectivity depends on the σp effect of the substituent in both cases; the differences are, however, rather small and the trend is opposite in the two cases. The regioselectivity displayed by 9 is still in favour of the less branched isomer but it is high only in the case of p-trifluoromethyl-2-phenylpropene. Larger differences with respect to the other catalytic systems were also observed for enantioselectivity but the trend for both regioselectivity and enantioselectivity is not linear.
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    The asymmetric hydroformylation in the synthesis of pharmaceuticals (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 355-369 
    Details
    ISSN: 0899-0042
    Keywords: enantiomerically pure compounds ; chiral drugs ; enantioselective hydroformylation ; enantioselective catalysts ; biologically active compounds ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The asymmetric hydroformylation reaction represents a potential powerful synthetic tool for the preparation of large number of different chiral products to be used as precursors of several organic compounds endowed with therapeutic activity. Essential and nonessential amino acids, 2-arylpropanoic acids, aryloxypropyl- and β-phenylpropylamines, modified β-phenylethylamines, pheniramines, and other classes of pharmaceuticals are available through enantioselective oxo-reaction of appropriate functionalized olefins; this process is catalyzed by rhodium or platinum complexes with chiral ligands, mainly chelating phosphines, and sometimes affords very high enantiomeric excesses. Furthermore, the application of many simple optically active aldehydes arising from asymmetric hydroformylation as chiral building blocks for the synthesis of complex pharmacologically active molecules such as antibiotics, peptides, antitumor macrocycle compounds, and prostaglandins is conveniently emphasized. The possibility of a future application of this asymmetric process for the production of many synthons to obtain other valuable pharmaceuticals is widely discussed too.
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    Masthead (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030501
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    Comments on a novel approach to the role of chirality in the origin of life (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 389-392 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; origin of life ; Bose condensation ; organic superconductivity ; electroweak interaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We review a recent paper20 in which a specific enhancement factor (i.e., a phase transition into a condensed Bose mode) is proposed to account for the observed amplification of the ground state energies of the L- and D-amino acid enantiomers; the difference between these energies is assumed to be due to the neutral parity-violating electroweak interaction. This physical effect initially shifts the enantiomer energies by about 3 × 10-19 eV. The proposed phase transition is characterized by a critical temperature Tc, which may be studied theoretically by enlarging the standard electroweak theory to include either the top quark or supersymmetry21. Possible experimental means of finding Tc are discussed.
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    An evaluation of ibuprofen bioinversion by simulation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 418-421 
    Details
    ISSN: 0899-0042
    Keywords: chiral bioinversion ; pharmacokinetics ; (+)-(S)-ibuprofen ; (-)-(R)-ibuprofen ; rac-ibuprofen ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a pharmacokinetic model recently proposed to explain ibuprofen disposition in man,1 plasma concentrations of pure ibuprofen enantiomers were simulated following oral administration of (-)-(R)-ibuprofen, (+)-(S)-ibuprofen, or rac-ibuprofen. Simulated and literature values for AUC's were used to compare S/R ratios for different cases of the model and for different methods of calculating the fraction of R bioinverted to S. Numerical simulation using STELLA confirmed previous results for different cases of bioinversion. Simulated S/R AUC ratios, for administration of the racemate, ranged from 4.0 (presystemic bioinversion) to 1.66 (systemic bioinversion). Literature values for S/R AUC ratios averaged 1.53±0.2 for administration of the racemate; therefore, systemic bioinversion was concluded to be representative of ibuprofen disposition. Additional simulations of S/R AUC ratios, for administration of (-)-(R)-ibuprofen only, ranged from 1.5 (presystemic bioinversion) to 0.66 (systemic bioinversion). Literature values for S/R AUC ratios averaged 0.50±0.9 for administration of (-)-(R)-ibuprofen only, which again supported conclusions of systemic bioinversion. Using different equations for estimation of fraction of R inverted to S (FR→S), results based on simulated data were identical; however, FR→S values based on literature data were different. Therefore, assumptions made for different FR→S equations do not appear to be rigorous. Calculations of FR→S, based on literature data, averaged 0.52 overall, indicating bioavailability of (+)-(S)-ibuprofen may be similar for a 150 mg dose of (+)-(S)-ibuprofen compared to a 200 mg dose of racemate.
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    URL: http://dx.doi.org/10.1002/chir.530030507
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    Masthead (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030601
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    Stereoselective accumulation of the β-receptor blocking drug atenolol by human platelets (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 451-453 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective ; stereoisomers ; β-blockers ; adrenergic β-receptor blockaders ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the stereochemistry of accumulation of the hydrophilic β-adrenoceptor antagonist rac-atenolol by human platelets in vitro. The accumulation was slow, not reaching equilibrium until 90 min at 37°C. The uptake was temperature dependent with the accumulation at 37°C being 3-4 times greater than at 4°C. The accumulation was also stereoselective at 37°C, favoring the active (-)-enantiomer over the (+)-enantiomer by 2.3-fold. Reserpine, but not desipramine, inhibited the platelet accumulation of rac-atenolol enantiospecifically. This uptake profile is different from the platelet uptake of lipophilic β-blockers, which is characterized by nonspecific membrane binding, but similar to the carrier-mediated accumulation of the neurotransmitter norepinephrine by storage granules within the platelet.
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    URL: http://dx.doi.org/10.1002/chir.530030607
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    Stereoselective inhibition of diphenylhydantoin metabolism by p-hydroxyphenyl-phenylhydantoin enantiomers in rats (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 454-459 
    Details
    ISSN: 0899-0042
    Keywords: phenytoin ; product inhibition ; p-HPPH ; rat liver microsomes ; ligand-exchange chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Different doses of rac-p-HPPH (0.4 and 4 mg/h) were given repeatedly to rats infused with [14C]phenytoin. The serum levels of 14C-labeled and unlabeled p-HPPH, and [14C]phenytoin were measured by an HPLC method and radiometric analysis. The clearance of phenytoin and p-HPPH was determined by rate of dosing divided by the steady-state concentration. The phenytoin clearance was significantly lower in the high dose p-HPPH injection group than in the low dose group (87 versus 262 ml/h), whereas p-HPPH clearance showed no difference. The formation clearance of [14C]p-HPPH was also significantly lower in rats injected with high dose of p-HPPH (35 versus 169 ml/h). The clearance of other elimination pathways was also lower in rats with high dose of p-HPPH (53 versus 89 ml/h). The serum protein binding of phenytoin was lower in rats injected with high dose of p-HPPH. The result indicated that injections of rac-p-HPPH mainly inhibited on the formation of p-HPPH itself. The formation of (R)-p-HPPH and (S)-p-HPPH in microsomal preparation was measured by a ligand-exchange chromatographic method. The formation of (S)-p-HPPH or (R)-p-HPPH was not only inhibited by the enantiomer itself, but also cross-inhibited by the other enantiomer. To the formation of either (S)-p-HPPH or (R)-p-HPPH, (S)-p-HPPH showed a higher inhibitory activity. The use of rac-p-HPPH to inhibit phenytoin metabolism in vivo involved several mechanisms. In addition to binding displacement on the serum proteins, one is the product inhibition by the respective p-HPPH metabolite, the other is the competitive inhibition by the other p-HPPH enantiomer.
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    URL: http://dx.doi.org/10.1002/chir.530030608
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    N,N-dimethylcarbamyl derivatives of oxazepam (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 212-219 
    Details
    ISSN: 0899-0042
    Keywords: oxazepam ; demoxepam ; 3-O-acyl-1-(N,N-dimethylcarbamyl)oxazepam ; 1-(N,N-dimethylcarbamyl)oxazepam ; 3-O-(N,N-dimethylcarbamyl)oxazepam ; camazepam ; norcamazepam ; 1,3-O-bis(N,N-dimethylcarbamyl)oxazepam ; kinetics of racemization ; enantioselectivity of esterases ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three N,N-dimethylcarbamyl derivatives of oxazepam {1-(N,N-dimethylcarbamyl)oxazepam, 3-O-(N,N-dimethylcarbamyl)oxazepam, and 1,3-O-bis(N,N-dimethylcarbamyl)oxazepam} and a 3-O-acyl-1-(N,N-dimethylcarbamyl)-oxazepam were synthesized from either oxazepam or demoxepam. Enantiomeric pairs of these derivatives and of camazepam were resolved by high-performance liquid chromatography on at least two of three commercially available chiral stationary phase columns employed. Absolute configurations of resolved enantiomers were established by comparing their circular dichroism spectra to those of enantiomeric oxazepams with known absolute stereochemistry. Similar to those of oxazepam, enantiomers of 1-(N,N-dimethylcarbamyl)oxazepam undergo rapid racemization (t½ 1.9 min at 23°C and 0.9 min at 37°C) in an aqueous solution at pH 7.5. The (R)-enantiomer of rac-3-O-acyl-1-(N,N-dimethylcarbamyl)oxazepam was hydrolyzed ∼4.6-fold faster than the (S)-enantiomer by esterases in rat liver microsomes, whereas the (S)-enantiomer was hydrolyzed ∼43-fold faster than the (R)-enantiomer by esterases in rat brain S9 fraction.
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    URL: http://dx.doi.org/10.1002/chir.530030313
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    Chirality of reverse micelles (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 233-241 
    Details
    ISSN: 0899-0042
    Keywords: circular dichroism ; 1(S),1′(S)-dimethylbisheptylsulphosuccinate sodium salt ; spectroscopy ; optical activity ; surfactant ; chiroptical properties ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four chiral analogues of the surfactant Aerosol-OT (AOT) have been synthesized and characterized. All of them form reverse micelles in apolar solvents in the w0 range 0-30 (w0 = [water]/[tenside]). Reverse micellar solutions have been investigated by UV absorption and circular dichroism spectroscopies with the aim of clarifying whether the formation of the macromolecular micellar structure induces the appearance of new chromophoric bands or perturbs the existing ones. Methanolic solutions of the surfactants, in which no micellar aggregates are formed, were taken as references. One of the products 1(S),1′(S)-dimethylbisheptylsulphosuccinate sodium salt (MH-AOT) was capable of forming reverse micelles of relatively high water content (w0 up to 40) and this process was accompanied by a specific increase in the intensity of the circular dichroism band associated with the ester absorbance of the molecule. As no concomitant changes were seen in the UV absorbance spectrum, it was concluded that this observation reflected conformational events occurring within the surfactant rather than chromophoric perturbation. These results are qualitatively similar to those found recently for lecithin reverse micelles which, however, form gels at sufficiently high water contents. The chiroptical properties of these supramolecular aggregates are compared with those of covalent macromolecular systems such as polypeptides.
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    URL: http://dx.doi.org/10.1002/chir.530030405
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    Evaluation of chiroptical properties of molecules by asymmetric photochemistry (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 257-262 
    Details
    ISSN: 0899-0042
    Keywords: chiral photochemistry ; excitation transfer ; optical activation ; circular dichroism ; dissymmetry factor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The physics involved in photochemistry with circularly polarized light, the warnings on its inherent limitations, as well as some examples of application on organic molecules are briefly reviewed.
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    URL: http://dx.doi.org/10.1002/chir.530030408
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    Helix-sense-selective polymerization of diphenyl-2-pyridylmethyl methacrylate with chiral anionic initiators (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 277-284 
    Details
    ISSN: 0899-0042
    Keywords: asymmetric polymerization ; stereospecific polymerization ; optically active polymer ; helix ; (+)-tartaric acid ; L-proline ; (+)-(S)-2-(1-pyrrolidinylmethyl)pyrrolidine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of diphenyl-2-pyridylmethyl methacrylate was carried out with the complexes of organolithium compounds with 22 chiral ligands. Helix-sense-selectivity of the polymerization was largely affected by a slight structural difference of chiral ligands. (+)-(S)-2-(1-Pyrrolidinylmethyl)pyrrolidine was the most effective ligand in producing a one-handed helical polymer with narrow molecular weight distribution.
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    Chiral liquid-crystalline side chain polymers by enantioselective modification of prochiral parent polymers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 307-314 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation is reported of two side chain polyacrylate samples 1a,b containing a sulfide group linked to the mesogenic core. By oxidation with a preferentially chiral oxaziridine, samples 1a,b were chemoselectively and enantioselectively converted to the corresponding sulfoxide containing polymers 2a,b with an estimated 20% asymmetric induction. The mesophasic behaviour of the parent and oxidized polymer samples is analyzed by thermal and optical techniques. The modification of the prochiral sulfide groups into chiral sulfoxide groups slightly depresses the propensity of the resulting polymers to give stable and persistent mesophases.
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    Polypeptide models of elastin: CD and NMR studies on synthetic poly(X-Gly-Gly) (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 318-323 
    Details
    ISSN: 0899-0042
    Keywords: nuclear magnetic resonance ; circular dichroism ; β-turn conformation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(X-Gly-Gly), simple structural models for the hydrophobic, proline-devoid, regions of elastin, have been synthesized and studied by circular dichroism and NMR spectroscopies. The results gave evidence of type II β-turns as the only ordered structure present in the polymers. The stability of the turns has been shown to decrease on hydration and to increase in the series Leu 〈 Ala 〈 Val 〈 Ile.
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    Cooperativity of chirality in homogeneous catalysis: The gold(I)-catalyzed aldol reaction and the vanadium(IV)-catalyzed hetero Diels-Alder cycloaddition (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 331-340 
    Details
    ISSN: 0899-0042
    Keywords: asymmetric synthesis ; enantioselectivity ; diastereoselectivity ; double stereodifferentiation ; chiral ferrocenyl ligands ; bis(1,3-diketonato)oxovanadium(IV) complexes ; oxazolines ; dihydropyrones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The notion of internal (or intramolecular) cooperativity of chirality is reviewed on the basis of various examples of diastereoisomeric ferrocenylphosphine ligands used in the gold(I)-catalyzed aldol reaction. It was found that the stereochemical outcome of this reaction strongly depends on the specific combination of the absolute configuration of the different stereogenic centers present in the ligand. Thus, individual chirotopic segments in these ligand molecules can act either in a cooperative or noncooperative manner in determining both diastereo-and enantioselectivity. Furthermore, several examples of application of the strategy of double stereodifferentiation (external, or intermolecular cooperativity of chirality) in the gold(I)-catalyzed aldol reaction and the vanadium(IV)-catalyzed hetero Diels-Alder condensation are presented. Based on our work it is apparent that, whether the diastereoselectivity of these two reactions is controlled by the catalyst or by a chiral substrate, cannot be predicted and very much depends on the nature of every individual reactant. Thus, it was found that in both reactions the chiral aldehyde substrate usually has a strong impact on the diastereoselectivity, leading to interesting patterns of double asymmetric induction. On the other hand, chiral isocyanoacetate and chiral-activated dienes, respectively, showed little or no effect on the stereochemical outcome of the reactions.
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    Circular dichroism detection in HPLC (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 376-385 
    Details
    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.
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    Enantioselectivity of lipase-catalyzed hydrolysis of some 2-chloroethyl 2-arylpropanoates studied by chiral reversed-phase liquid chromatographySecond International Symposium on Chiral Discrimination, May 27 - 31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 98-102 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective hydrolysis ; lipase ; 2-chloroethyl esters ; 2-arylpropanoic acids ; chiral liquid chromatography ; enantiomer separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A technique based exclusively on chiral reversed-phase liquid chromatography has been shown to greatly facilitate studies of enantioselectivity in lipase-catalyzed hydrolysis of chiral organic esters. Only two sets of experimental data are needed to calculate the enantioselectivity (E) of a kinetically controlled enantiomer-differentiating reaction of this kind, viz. the enantiomeric excess of the product (eep) or substrate (ees), and the degree of substrate conversion (c). The product enantiomers are well separated on a BSA-based column, giving eep directly. In addition, separation of the (unresolved) ester substrate from the enantiomeric products gives c by integration. Via an optimization of the mobile phase used in the chiral chromatographic system, both these parameters can often be determined in a single run. Highly precise and detailed kinetic studies of the enzymatic reaction can thus be performed. In this way, E-values have been determined for a series of 2-chloroethyl 2-arylpropanoates hydrolyzed in the presence of a Candida cylindracea lipase at pH 6.0 and 7.1. Effects on the E-values from a partial purification and further processing of the lipase have also been studied.
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    Enzymatic resolutions of α- and β-hydroxypropionic acid esters (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 103-109 
    Details
    ISSN: 0899-0042
    Keywords: dihydrocinnamic acid derivatives ; hydroxy azido acids ; hydroxy amino acids ; enantioselective hydrolysis ; Pseudomonas fl. lipase ; Candida cyclindracea lipase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of some acyloxy-methoxy-cinnamic acid derivatives, azidohydroxy butanoates, and azidohydroxy butanedioates in enantiomerically pure form is presented. Racemic diastereomerically pure educts were prepared in few steps. These racemates are resolved with lipases from Candida cylindracea (CC) and Pseudomonas fluorescens (P).
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    Optical resolution of β-lactams on 1-phenylethylcarbamates of cellulose and amylose (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 122-124 
    Details
    ISSN: 0899-0042
    Keywords: 4-acetoxy-2-azetidinone ; antibiotics ; carbapenem ; HPLC ; chiral stationary phases ; cellulose tris(1-phenylethylcarbamate) ; amylose tris(1-phenylethylcarbamate) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical resolution of six β-lactams was examined by HPLC using chiral stationary phases consisting of tris((R)-, (RS)-, and (S)-1-phenylethylcarbamate)s of cellulose and amylose. All β-lactams were optically resolved at least by one of the carbamates. Amylose tris((S)-1-phenylethylcarbamate) showed high optical resolving abilities for some β-lactams.
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    Cyclodextrin derivatives in GC separation of racemic mixtures of volatiles: Part IIISecond International Symposium on Chiral Discrimination, May 27 - 31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 125-131 
    Details
    ISSN: 0899-0042
    Keywords: capillary gas chromatography ; enantiomer resolution ; cyclodextrin derivatives ; chromatographic performance ; cyclodextrin/OV-1701 dilution ; operative temperature ; film thickness ; column length ; column conditioning ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic performance of differently derivatized α-, β-, and γ-cyclodextrins in the separation of racemic mixtures of volatiles is investigated. The performances of 2,3,6-permethylated α-, β-, and γ;-cyclodextrins and 2,6-dimethyl-3-trifluoro-acetyl α-, β-, and γ-cyclodextrins mixed with different ratios of OV-1701 or OV-1701-OH terminated were tested with racemates with widely differing structures. The influence of the percentage of cyclodextrins in polysiloxane, of film thickness of the stationary phase, of the length of the column, of column conditioning, and of the operating temperatures in the separations of different racemates has been evaluated.
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    Stereoselective disposition and tissue distribution of carvedilol enantiomers in rats (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 148-154 
    Details
    ISSN: 0899-0042
    Keywords: carvedilol enantiomers ; kinetics ; tissue-to-blood partition coefficient ; plasma protein binding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After intravenous bolus injection of rac-carvedilol at 2 mg/kg to the rat, the (+)-(R)- and ( - )-(S)-enantiomer levels in the blood and tissues (liver, kidney, heart, muscle, spleen, and aorta) were measured by stereospecific HPLC assay. As compared with the (+)-(R), the ( - )-(S) had a larger Vdss (3.32 vs. 2.21 liter/kg), MRT (33.4 vs. 25.6 min), and CLtot (96.1 vs. 83.8 ml/min/kg). AUC comparison after iv and po administration showed systemic bioavailability of the ( - )-(S) to be about half that of its antipode, explained by the fact that the free fraction of the ( - )-(S) in blood was 1.65-fold greater than that of the (+)-(R). Tissue-to-blood partition coefficient values for the ( - )-(S) were 1.6- to 2.1-fold greater than those for the (+)-(R) in all tissues, showing that the ( - )-(S) accumulates more extensively in the tissues. These results were consistent with the greater Vdss for the ( - )-(S) estimated from systemic blood data. The stereoselective tissue distribution of carvedilol enantiomers results from an enantiomeric difference in plasma protein binding rather than in tissue binding. © 1992 Wiley-Liss, Inc.
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    Liquid chromatographic separation of chiral diarylcarbinolsSecond International Symposium on Chiral Discrimination, May 27-31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 170-173 
    Details
    ISSN: 0899-0042
    Keywords: chiral phases ; chiral recognition mechanism ; alcohols ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct HPLC separation of three chiral carbinols of general formula Mesityl-CH(OH)-Aryl has been achieved using Pirkle (R)-DNBPG ionic or covalent columns and, for Aryl = o-tolyl, on a Chiralpak OP(+) phase. It is apparent that steric hindrance and hydrogen bonding play important roles in chiral recognition. Two compounds structurally very similar but lacking the hydroxyl group were not resolved in their enantiomeric pairs. © 1992 Wiley-Liss, Inc.
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    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040401
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    Spontaneous racemization of chlorthalidone: kinetics and activation parameters (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 222-226 
    Details
    ISSN: 0899-0042
    Keywords: 3-hydroxy-3-phenylphthalimidines ; inversion (of configuration) ; barrier to inversion ; rate constants (of inversion) ; enantiomer interconversion ; carbonium ion (intermediate in racemization) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of chlorthalidone (CTD) and a minor, achiral dehydration product, δ2-CTD, are shown to exist in dynamic equilibrium in aqueous media through a carbonium ion intermediate. The barrier to inversion at carbon is low for an uncatalyzed system: ΔG
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    Stereoselective binding of etodolac to human serum albuminPresented at the Second International Symposium on Chiral Discrimination, May 27-31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 240-246 
    Details
    ISSN: 0899-0042
    Keywords: NSAID ; chirality ; enantiomers ; protein binding ; equilibrium dialysis ; fluorescent specific markers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The protein binding of etodolac enantiomers was studied in vitro by equilibrium dialysis in human serum albumin (HSA) of various concentrations varying from 1 to 40 g/liter, by addition of each enantiomer at increasing concentrations. In the 1 g/liter solution, at the lowest drug levels, the (R)-form is more bound than its antipode, the contrary being observed at the highest drug levels. For higher albumin concentrations, S was bound in a larger extent than R. Using the displacement of specific markers of HSA sites I and II, studied by spectrofluorimetry, it was suggested that R and S are both bound to site I, while only S is strongly bound to site II. © 1992 Wiley-Liss, Inc.
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    Resolution of terfenadine enantiomers by β-cyclodextrin chiral stationary phase high-performance liquid chromatography (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 268-272 
    Details
    ISSN: 0899-0042
    Keywords: HPLC ; chiral stationary phase ; optical isomers ; absolute configuration ; circular dichroism ; chiral ; enantiomers ; terfenadine ; cyclodextrin ; normal phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomers of terfenadine were resolved by high-performance liquid chromatography (HPLC) using a chiral stationary phase (CSP) column packed with β-cyclodextrin (β-CD) covalently bound to silica. Separation was achieved in both the reverse phase and normal phase modes. Resolution of enantiomers was confirmed by ultraviolet-visible absorption, circular dichroism, and mass spectral analysis.
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    Obituary: professor goran schill (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 273-273 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530040502
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    Effects of the stereochemical orientation of phenethylamines and imidazolines on α-adrenergic receptor-mediated dna synthesis in primary cultured rat hepatocytes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 279-285 
    Details
    ISSN: 0899-0042
    Keywords: stereochemistry ; catecholamines ; DNA synthesis ; liver regeneration ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hepatic α1-adrenergic receptor mediates a variety of hepatic functions including respiration, glycogenolysis, gluconeogenesis, and growth. We have utilized a rat primary hepatocyte culture system to show that the α1-adrenergic receptor can be activated in a stereoselective manner by a series of phenethylamines and catecholimidazolines resulting in the stimulation of DNA synthesis as determined by [3H]thymidine incorporation. The phenethylamines adhered to the Easson-Stedman hypothesis with a rank order of potency of (-)-(R)-norepinephrine (NE) 〉 (+)-(S)-NE 〉 the desoxy analog dopamine (DA) for the stimulation of DNA synthesis. However, the 2-substituted catecholimidazolines did not follow this trend and demonstrated an order of potency of the desoxy analog 3,4-dihydroxybenzyl imidazoline (DHT) ≥ (-)-(R)-2-(3,4,α-trihydroxybenzyl)imidazoline (TBI) 〉 (+)-(S)-TBI. 4-Substituted catecholimidazolines were less potent as inducers of DNA synthesis than the corresponding 2-substituted analogs with an order of potency of (+)-(R)-4-(3,4-dihydroxybenzyl)imidazoline (DBI) 〉 (+, -)-(R,S)-DBI 〉 (-)-(S)-DBI. When the β-hydroxyl moiety of NE is replaced with an amino group as in 3,4-dihydroxyphenylethylenediamine, the isomers are less active than the β-hydroxylated analogs and also demonstrate no stereoselectivity for the stimulation of DNA synthesis. These results demonstrate that the hepatic α1-adrenergic receptor can recognize various isomeric forms of these compounds and that hepatocellular growth can be modulated in a stereoselective manner by phenethylamines and imidazolines. © 1992 Wiley-Liss, Inc.
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    Some mechanistic aspects on chiral discrimination of organic acids by immobilized bovine serum albumin (BSA) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 24-29 
    Details
    ISSN: 0899-0042
    Keywords: organic acids ; enantiomers ; BSA ; chiral discrimination ; hydrophobic interaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Although chiral anionic compounds, notably a large number of organic acids, have been found to be readily separated into enantiomers on BSA-based columns, the structural requirements for an efficient enantiomer discrimination by the protein is still not very well known. Since it is often observed that very hydrophobic acids, like many of the antiinflammatory “profens,” can be resolved with large separation factors for the enantiomers, a systematic study of a series of racemic α-substituted alkanoic acids was made. The series of analytes was prepared from α-amino acids, RCH(NH2)CO2H (where R = C1-C6), by reaction with N-(chloroformyl)-carbazole. A rapid increase in the capacity ratios of both enantiomers was found with increasing length of R. The effect, however, was larger for the last eluted enantiomer, leading to a substantial increase in the separation factor; this being 7.3 for R = C6 in 20 mM phosphate buffer (pH 8.0) with 30% of acetonitrile. Further, the separation factor also increased with decreasing organic modifier content. Thus when the R = C6-analyte was run at a mobile phase concentration of 20% acetonitrile and a flow rate of 1.5 ml/min, the time difference between the two eluted enantiomers exceeded 20 hr.A reasonable interpretation of our results seems to be that enantioselectivity is promoted by increased hydrophobic interaction. Since the anionic charge of the analyte is also taking part in the retention mechanism, a tight binding of the analyte will result from simultaneous electrostatic and hydrophobic interaction. When the latter is increased, less conformational freedom will be left for the analyte and the steric configuration at the α-carbon atom will become more and more important. Steric hindrance by the α-substituent in the first eluted enantiomer will counteract the tight binding caused by the combined binding interactions and lead to a smaller increase in the capacity ratio.
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    4',6-Dichloroflavan (BW683C): Enantiomeric separation by hplc/dad and antirhinovirus activity (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 65-67 
    Details
    ISSN: 0899-0042
    Keywords: optical resolution ; chiral HPLC ; chiral stationary phase ; 4',6-dichloroflavan ; circular dichroism ; antirhinovirus activity ; BW683C ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic 4',6-dichloroflavan (BW683C), a highly effective inhibitor of rhinovirus serotype 1B in vitro, was resolved by high-performance liquid chromatography on a chiral stationary phase. The enantiomers were separately collected and circular dichroism curves were obtained, in order to determine the absolute configuration of the two enantiomers. The activity of the isomers was studied on human rhinovirus serotype 1B multiplication in HeLa cell cultures, by means of the plaque reduction assay. Both enantiomers were potent inhibitors of virus replication; by comparing the IC50 values, the S form was 3.5 times more effective than the R form.
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    Erratum (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 71-71 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530040116
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    Pulmonary inversion of 2-arylpropionic acids: Influence of protein binding (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 349-352 
    Details
    ISSN: 0899-0042
    Keywords: ibuprofen ; fenoprofen ; flurbiprofen ; rabbit lung ; first-pass ; presystemic ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The possible contribution of pulmonary metabolism to the putative first-pass metabolism of 2-arylpropionic acid nonsteroidal antiinflammatory drugs has not been documented. Isolated perfused rabbit lungs, perfused with 4.5% bovine serum albumin or 5% dextran, were used to study the pulmonary elimination of (R)- and rac-ibuprofen, fenoprofen, and flurbiprofen. In the absence of protein binding, ibuprofen was metabolized via inversion and other pathways, whereas fenoprofen metabolism was essentially restricted to inversion of the (R)-enantiomer; fraction inverted (± SE) was 0.37 ± 0.05 for (R)-ibuprofen and 0.85 ± 0.03 for (R)-fenoprofen. In the presence of protein, neither ibuprofen nor fenoprofen was metabolized. Flurbiprofen did not undergo pulmonary elimination under any condition studied. This study illustrates that even though a tissue is capable of metabolism, particularly inversion of 2-arylpropionics, the quantitative importance of such elimination pathways may be minimal in the presence of the high degree of protein binding that is characteristic of these drugs. © 1992 Wiley-Liss, Inc.
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    Formation of glycine conjugate and (-)-(R)-enantiomer from (+)-(S)-2-phenylpropionic acid suggesting the formation of the coa thioester intermediate of (+)-(S)-enantiomer in dogs (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 342-348 
    Details
    ISSN: 0899-0042
    Keywords: arylpropionic acid ; 2-phenylpropionic acid ; glycine conjugation ; stereoselectivity ; chiral inversion ; reverse chiral inversion ; glycine N-acyl transferase ; dog hepatocytes ; chiral HPLC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been proposed that the chiral inversion of the 2-arylpropionic acids is due to the stereospecific formation of the (-)-R-profenyl-CoA thioesters which are putative intermediates in the inversion. Accordingly, amino acid conjugation, for which the CoA thioesters are obligate intermediates, should be restricted to those optical forms which give rise to the (-)-R-profenyl-CoA, i.e., the racemates and the (-)-(R)-isomers. We have examined this problem in dogs with respect to 2-phenylpropionic acid(2-PPA). Regardless of the optical configuration of 2-phenylpropionic acid administered, the glycine conjugate was the major urinary metabolite and this was shown to be exclusively the (+)-(S)-enantiomer by chiral HPLC. Both (-)-(R)- and (+)-(S)-2-phenylpropionic acid were present in plasma after the administration of either antipode, and further evidence of the chiral inversion of both enantiomers was provided by the presence of some 25% of the opposite enantiomer in the free 2-phenylpropionic acid and its glucuronide excreted in urine after administration of (-)-(R)- and (+)-(S)-2-phenylpropionic acid. The (+)-(S)-enantiomer underwent chiral inversion to the (-)-(R)-antipode when incubated with dog hepatocytes. These data suggests that both enantiomers of 2-phenylpropionic acid are substrates for canine hepatic acyl CoA ligase(s) and thus undergo chiral inversion, but that the CoA thioester of only (+)-(S)-2-phenylpropionic acid is a substrate for the glycine N-acyl transferase. These studies are presently being extended to the structure and species specificity of the reverse inversion and amino acid conjugation of profen NSAIDs. © 1992 Wiley-Liss, Inc.
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    HPLC resolution of atropoisomeric compounds on a csp derived from (1R;2R)-diaminocyclohexane: Thermodynamic data from variable temperature chromatographyThis paper was presented at the Second International Symposium on Chiral Discrimination, May 27-31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 384-388 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separations ; polymeric CSPs ; enthalpy ; entropy ; H-bonding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation and a preliminary chromatographic evaluation of a novel polymeric chiral stationary phase (CSP) derived from (1R;2R)-diaminocyclohexane (DACH) are presented. A radical copolymerization process has been employed to generate a silica-based chiral sorbent, showing considerable high chemical and thermal stability and stereoselectivity toward racemic compounds capable of H-bonding (3-hydroxy-benzodiazepin-2-ones, chlorthalidone, atropoisomeric sulfur compounds, etc.); in the present paper we present the investigation on the resolution of racemic dihydroxy biarylic atropoisomers; the effects of eluent composition and of temperature on the separation ability of the CSP have been studied in order to elucidate the recognition mechanism operating in these chiral separations. © 1992 Wiley-Liss, Inc.
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    Announcement (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 406-406 
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    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530040614
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    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530040701
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    Optical resolution of unusual amino acids using microbial proteases (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 427-431 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective hydrolysis ; amino acid enantiomers ; Aspergillus oryzae protease ; Bacillus subtilis protease ; enantioselectivity ; enantiomeric purity determination ; HPLC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have developed novel enzymatic methods for the optical resolution of unusual amino acids. In this work, we tried two microbial proteases, available inexpensively in a crude state, from Aspergillus oryzae and from Bacillus subtilis. The enantioselective hydrolysis of the methyl esters of the N-benzyloxycarbonyl (Z) derivatives of a number of amino acids, both aliphatic and aromatic, was examined using these microbial proteases. The enantiomeric purities of the resolved Z-amino acids were determined accurately by methods based on the reversed-phase HPLC separation of diastereomeric derivatives or the HPLC separation of enantiomeric derivatives on chiral stationary phases. In general, B. subtilis protease yielded better results than A. oryzae protease. Using the former protease, the amino acids bearing aliphatic side chains were resolved with good to excellent enantioselectivities and reasonable hydrolysis rates. The speed of hydrolysis was reduced significantly when the length of the side chain was longer than 5 carbon atoms. Phenylalanine, halogenated phenylalanines, and phenylalanine homologs were also resolved, generally with high enantiomeric purities, though the hydrolysis rates were not always reasonably fast. In all the cases examined, the L-enantiomers were preferentially hydrolyzed as in the lipase-catalyzed enantioselective hydrolysis reported previously. © 1992 Wiley-Liss, Inc.
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    Resolution and adrenergic activities of the optical isomers of 4-[1-(1-Naphthyl)ethyl]-1H-imidazole (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 432-438 
    Details
    ISSN: 0899-0042
    Keywords: α-adrenergic ; imidayole analogs ; metetomidine ; enantiomers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently we synthesized a naphthalene analog of medetomidine, 4-[1-(1-naphthyl)ethyl]-1H-imidazole hydrochloride (1), and found it to be highly potent in adrenergic systems. The separation of optical isomers of this naphthalene analog was achieved by using the isomers of tartaric acid. The optical purities of the isomers were determined by HPLC using a chiral column. Using X-ray analysis the (+)-isomer was determined to have the S absolute configuration. It has been reported that the (+)-isomer of medetomidine (2) is the most potent enantiomer on α2-adrenergic receptors. There were both qualitative and quantitative differences in biological activities of the optical isomers of 1 in α1- and α2-adrenergic receptor systems of guinea pig ileum and human platelets. (+)-(S)-1, but not ( - )-(R)-1 was a selective agonist of α2-mediated responses in ileum whereas ( - )-(R)-1 was more potent than (+)-(S)-1 as an inhibitor of α2-mediated platelet aggregation. © 1992 Wiley-Liss, Inc.
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    Announcement (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 462-463 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040711
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    Optical stability of gossypol (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 216-221 
    Details
    ISSN: 0899-0042
    Keywords: atropisomerism ; gossypol stereochemistry ; molecular mechanics ; circular dichroism ; anhydrogossypol ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical stability of gossypol [1,1',6,6',7,7'-hexahydroxy-3,3'-dimetyl-5,5'-bis(1-methylethyl)-2,2'-binaphthalene-8,8'-dicarboxaldehyde], a natural product exhibiting profoundly enantiospecific antitumor and male antifertility action, was investigated by means of computational methods and thermal racemization experiments. The calculations on gossypol and several derivatives and model compounds were carried out using the MM2 force field; energies and geometries of minimum energy conformations, as well as structures along various inversion pathways, were calculated. According to the calculations, gossypol (the dialdehyde form) and its simple analogues are not thermally racemizable (energy barriers for rotational inversion above 50 kcal/mol). By contrast, the calculations suggest that the acetal tautomer of gossypol and its dehydration product (anhydrogossypol) are thermally racemizable, although the energy barriers are still relatively high (35-40 kcal/mol). Optically pure (+)-anhydrogossypol was prepared and characterized; its racemization became rapid only at high temperatures (180-200°C). When dehydration of gossypol was hindered (in aqueous solution), no racemization of gossypol was observed after prolonged heating at 90°C. © 1992 Wiley-Liss, Inc.
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    Synthesis and pharmacological investigation of stereoisomeric muscarines (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 230-239 
    Details
    ISSN: 0899-0042
    Keywords: total synthesis ; chiral muscarines ; iodocyclization process ; muscarinic receptor subtypes M1, M2, and M3 ; affinity states ; eudismic ratio ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the eight stereoisomers of muscarine has been efficiently accomplished by utilizing the two enantiomers of lactic esters as starting material. The synthetic strategy is based on a SnCl4-catalyzed addition of allyltrimethylsilane to O-protected lactic aldehydes followed by an iodocyclization process. All the final derivatives possess an enantiomeric excess higher than 98%. The four pairs of enantiomers bound to M1, M2, and M3 muscarinic receptor subtypes in membranes from cerebral cortex, heart, and salivary glands, respectively, and recognized heterogeneous states of the receptors. Of the eight isomers, only natural muscarine (+)-1 recognized three affinity states of the M2 receptor. The compound was also the only one to show selectivity in the binding study, demonstrating 37- to 44-fold higher affinity for the M2 than for the M1 or M3 receptors. In addition, the compounds were tested in functional assays on isolated guinea pig atria (M2 receptors) and ileum (mixed population of M2 and M3 receptors) and their muscarinic potencies were determined. Among the eight isomers, again only (+)-1 enantiomer was found to be very active on both tissues. Its potency was more than two orders of magnitude higher than that of its enantiomer (-)-1 as well as the other six isomers. The eudismic ratios (E.R.) deduced from the two functional tests were 324 and 331. © 1992 Wiley-Liss, Inc.
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    Discrimination in resolving systems: Ephedrine-mandelic acid (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 494-504 
    Details
    ISSN: 0899-0042
    Keywords: diastereomers ; crystal structures ; isosterism ; organic salts ; molecular recognition ; hydrogen bonding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resolution of mandelic acid with ( - )-(1R,2S)-ephedrine in water and ethanol produces intermediate diastereomeric salts with greatly disparate solubilities and melting points. Single crystal X-ray analysis of the less (L) and more (M) soluble ( - )-ephedrinium mandelates (I, II) shows crystal structures which are isosteric, each crystallizing in the monoclinic system, space group C2. Protonated ephedrines occupy the same relative positions in the L- and M-salts, and mandelates are in the same general locations. Hydrogen bonds link alternating protonated ephedrine nitrogens and mandelate carboxylate oxygens in each salt forming columns of ions. The helical H-bonded chain winds down the crystallographic 2-fold screw axis. Additional H-bonds form between 2-fold related mandelates in the L-salt. Mixed crystals, containing both mandelate isomers, (2R)- and (2S)-mandelates, are obtained from the resolving system partly depleted of the L-salt. A specimen with nearly equal amounts of the mandelates (III) is also isosteric with the commensurate structures. I (294K), L-salt: a = 18.160(7), b = 6.538(2), c = 13.898(4) Å, β = 92.02(3)°, V = 1649.1(9) Å3; IIa (294K), M-salt: a = 17.978(11), b = 7.164(4), c = 13.574(6)Å, β = 96.41(4)°, V = 1737.3(16) Å3; IIb (223K), M-salt: a = 17.805(8), b = 7.115(2), c = 13.50(5) Å, β = 96.89(3)°, V = 1697.9(15) Å3; III (294K), mixed-salt: a = 18.184(22), b = 6.792(7), c = 13.808(19) Å, β = 93.74(10)°, V = 1701.7(35) Å3. © 1992 Wiley-Liss, Inc.
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    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530050101
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    Rats with portacaval shunt as a potential experimental pharmacokinetic model for liver cirrhosis: Application to carvedilol stereopharmacokinetics (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 1-7 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; conjugates ; protein binding ; tissue binding ; stereoselective pharmacokinetics ; first-pass effect ; drug metabolism ; liver disease ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an experimental model for reduced liver function rats with surgical portacaval shunts (pcs) may be used. Carvedilol, a nonselective β-adrenoceptor antagonist with vasodilating activity, is extensively metabolised by phase I as well as phase II pathways. In order to study the stereoselective pharmacokinetics of carvedilol in liver disease, pcs and control rats were given rac-carvedilol intravenously and p.o. The carvedilol enantiomers and their conjugates were assayed in plasma, urine, and bile. Carvedilol was highly bound to plasma proteins; binding was reduced by pcs. In all groups, the plasma concentrations of (R)-carvedilol exceeded those of (S)-carvedilol significantly. In comparison to the control group the plasma concentrations of both enantiomers increased after pcs, while the difference between the stereoisomers decreased. The total clearance decreased proportionally to the decrease in liver weight (30%). Both the apparent oral clearance, as well as its stereoselectivity were reduced, by up to 90 and 43%, respectively. The biliary clearance of the parent drug after i.v. dosage increased in rats with pcs due to the reduced hepatic metabolism. © 1993 Wiley-Liss, Inc.
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    High enantiofacial selectivity in the OsO4 dihydroxylation of e-stilbene with a chiral biphenyl diamine catalyst (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 300-301 
    Details
    ISSN: 0899-0042
    Keywords: hydrobenzoin ; asymmetric oxidation ; osmium tetroxide ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral biphenyl-containing diamine 1 complexed with OsO4 oxidized trans-stilbene at -80°C to (+)-(1R;2R)-1,2-diphenyl-1,2-ethanediol in high enantiomeric excess. On the other hand, (R)- or (S)-2,2'-bis(dimethylamino)-6,6'-dimethylbiphenyl proved to be ineffective in promoting oxidation. © 1992 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/chir.530040507
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    Enantio- and regioselectivity in the epoxide-hydrolase-catalyzed ring opening of aliphatic oxiranes: Part II: Dialkyl- and trialkylsubstituted oxiranes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 185-192 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective hydrolysis ; regioselective hydrolysis ; epoxide hydrolase ; product enantioselectivity ; substrate enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extent of substrate enantioselectivity and regioselectivity of a series of aliphatic 2,3-dialkyl- and trialkylsubstituted oxiranes in their in vitro epoxide-hydrolase-catalyzed hydrolysis depends on the size of the alkyl residues and on the substitution pattern of the oxirane ring. The enzyme-catalyzed hydrolysis of cis-oxiranes, containing at least one methyl substituent, shows complete or nearly complete substrate enantioselectivity and regioselectivity with nucleophilic attack by water occurring with inversion of configuration at the methylsubstituted ring carbon atom of (S)-configuration. In the hydrolysis of the isomeric trans-oxiranes, both enantiomers are metabolized with a higher rate for the (2S;3S)-enantiomer. The conversion of trimethyloxirane occurs with high substrate enantioselectivity in favor of the (S)-enantiomer and with complete regioselectivity at the monomethylsubstituted ring carbon atom. The differentiation of the enantiotopic ring carbon atoms (product enantioselectivity) in the smallest aliphatic meso-oxirane, cis-2,3-dimethyloxirane, leads to (2R;3R)-butane-2,3-diol with ee = 86%. cis-2-Ethyl-3-propyloxirane, possessing alkyl residues larger than methyl, represents an extremely poor substrate in the epoxide-hydrolase-catalyzed hydrolysis process. © 1992 Wiley-Liss, Inc.
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    Structural characteristics of cyclodextrins in the solid state (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 205-215 
    Details
    ISSN: 0899-0042
    Keywords: cyclodextrins ; molecular mechanics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comparison of α-, β and γ-cyclodextrins in the solid state is made. Monomeric features analyzed include orientations of primary hydroxyl groups and pyran ring pucker. Macromolecular features examined include planarity of the oligomer, tilting of pyran rings, and, deviation from Cn symmetry where n = number of monomers. The mean values and standard deviations of these shape descriptors are given for cyclodextrins with and without guests embedded in their interiors. Molecular mechanics calculations using the MM2, AMBER, and CHARMM force fields show that most solid state cyclodextrins are trapped in high-energy conformations relative to the most stable forms found in this study. © 1992 Wiley-Liss, Inc.
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    Enantioselective determination of hydroxychloroquine and its major metabolites in urine and the observation of a reversal in the (+)/(-)-hydroxychloroquine ratio (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 65-70 
    Details
    ISSN: 0899-0042
    Keywords: stereoselective excretion ; enantioselective ; chromatography ; assay validation ; hydroxychloroquine metabolism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sequential achiral-chiral high-performance liquid chromatographic system has been developed for the quantitation in urine of the enantiomers of hydroxychloroquine (HCQ), and of its 3 major metabolites, desethylhydroxychloroquine (DHCQ), desethylchloroquine (DCQ), and bisdesethylchloroquine (BDCQ). HCQ and its metabolites were separated and quantified on a cyano-bonded phase, and the enantiomeric ratios were determined using a Chiral-AGP chiral stationary phase. The assay validation and application of this method to a preliminary study in a human volunteer are presented. In this subject, the initial 0-4 h urine contained the 2 HCQ enantiomers in a ratio of (+)-HCQ:(-)-HCQ of 3:2; by the 2,064 h of the study, this ratio had reversed to (+)-HCQ:(-)-HCQ of 3:7. © 1993 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/chir.530050205
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    Enzymes in stereoselective pharmacokinetics of endogenous substancesPresented at the Second International Symposium on Chiral Discrimination, May 27-31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 247-251 
    Details
    ISSN: 0899-0042
    Keywords: radioenzyme assay ; stereospecific assay ; carnitine acetyl transferase ; L-carnitine family ; L-carnitine ; acetyl-L-carnitine ; propionyl-L-carnitine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of enzymes to assay individual components of the L-carnitine family in pharmaceuticals, foodstuffs, and biological fluids with various forms of detection is reviewed. The most useful enzyme in the assay of compounds of the L-carnitine family is carnitine acetyl transferase (CAT), which catalyses the reversible interconversion of L-carnitine and its short-chain acyl esters. CAT can be used in one or more coupled reactions combined with U.V., or radiolabelled detection, or combined with HPLC, allowing, enantioselective, structurally specific, and, in the case of radiolabelled tracing, highly sensitive assays to be carried out. When compared with chromatographic separation of enantiomers or diastereoisomers, enantioselective enzyme mediated assays may be cheaper, more sensitive, and simpler, but they do not allow the nonpreferred isomer to be assayed. Consequently, they are appropriate for the specific assay of endogenous enantiomeric substrates of the enzyme concerned, in biological samples. The analysis of the other enantiomer in raw materials or in pharmaceuticals must be more properly approached by enantioselective chromatographic methods.
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    Direct enantiomeric separation of β-blockers on ChyRoSine-a by supercritical fluid chromatography: Supercritical carbon dioxide as transient in situ derivatizing agent (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 252-262 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separations ; chiral stationary phases ; tyrosine chiral selector ; supercritical fluid chromatography ; 1,2-amino-alcohols ; β-blockers ; carbon dioxide ; 1H NMR ; ChyRoSine CSP ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct enantiomeric separation of a series of β-blockers has been carried out on two chiral stationary phases (CSPs) derived from 3,5-dinitrobenzoyl tyrosine: the commercially available ChyRoSine-A and a recent improved version of this CSP.Using supercritical fluid chromatography (SFC), facile separations are achieved (1.1 〈Rs 〈7) within short analysis times. The parameters affecting the enantioselectivity (temperature, pressure, mobile phase nature, solute structure) have been investigated. The optimal mobile phase consists in a mixture of carbon dioxide-methanol-propylamine at 25°C. The solute structure has a great influence on the enantioselectivity. For instance, both amine and hydroxyl protons are necessary for chiral discrimination to occur. Furthermore, the steroselectivity value is directly connected to the amine substituent steric bulkiness.Surprisingly, these solutes are poorly resolved using normal phase liquid chromatography (NPLC). Accordingly, the specific influence of carbon dioxide on the enantiomeric separation of 1,2-amino-alcohols has been investigated using various techniques such as nuclear magnetic resonance (NMR) or molecular modelisation. It has been shown that carbon dioxide acts as a complexing agent toward the amino-alcohol by setting up of a bridge with the hydroxyl and the amine protons of the solute. In that way, the resulting complex possesses lower acido-basic properties and a higher conformational rigidity, responsible for chiral discrimination.
    Additional Material: 10 Ill.
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    A proposal for the representation of the stereochemistry of quadrivalent centers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 274-278 
    Details
    ISSN: 0899-0042
    Keywords: one-wedge diagram ; structure representation ; stereochemistry ; absolute configuration ; chiral center ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The broken wedge, broken line, solid bar, and broken bar are either not reasonable or can be replaced by only one type of solid wedge in the stereochemical formulation. A convention based on a one-wedge symbolization is proposed, where a or b is used instead of c, d, e, f, g, or h. © 1992 Wiley-Liss, Inc.
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    Asymmetric synthesis polymerization of meso oxiranes and thiiranesThis work is dedicated to the memory of Professor Piero Pino. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 295-299 
    Details
    ISSN: 0899-0042
    Keywords: cis-dimethylthiirane ; cyclohexene sulfide ; cis-dimethyloxirane ; cyclohexene oxide ; chiral initiator system ; enantiogenic polymerization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The asymmetric synthesis polymerization or “enantiogenic” polymerization of some meso oxiranes, cis-dimethyloxirane (cis-DMO) and cyclohexene oxide (CHO), and thiiranes, cis-dimethylthiirane (cis-DMT) and cyclohexene sulfide (CHS), initiated with different chiral systems was examined. Strong differences in behaviour were observed between oxiranes and thiiranes depending on the initiator used. The initiators based on ZnEt2 or CdMe2 and a chiral diol give optically active polymers from meso thiiranes but fail to induce an asymmetric polymer synthesis with meso oxiranes. A new chiral initiator based on ZnEt2 and (1S,2R)-ephedrine allowed us to prepare optically active poly CHOs, which can be fractionated into fractions exhibiting opposite optical activities. © 1992 Wiley-Liss, Inc.
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    Computer-Aided models for optimization of eluent parameters in chiral liquid chromatography (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 316-322 
    Details
    ISSN: 0899-0042
    Keywords: chiral LC ; drug enantiomers ; modelling ; central composite desire ; optimization ; β-cyclodextrin ; response surface ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of a central composite design to the enantiomeric separation of the antifungal drug tioconazole is investigated. The design involves application of a mathematical model to the data to model the response in regions of the factor space not investigated in the experimental design. The significance of the variable terms in the model is assessed statistically and those terms declared not significant are removed from the model. The statistical adequacy of these reduced models is discussed, together with an examination of the prediction errors of the models. Three-dimensional predicted response surfaces for the complete models are presented and the predictive performance assessed. © 1992 Wiley-Liss, Inc.
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    Resolution of the enantiomers of drugs containing amino alcohol structure after derivatization with bromoacetic acid (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 333-337 
    Details
    ISSN: 0899-0042
    Keywords: chiral separation ; ligand exchange chromatography ; adrenergic drugs ; β-blockers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation of the enantiomers of drugs containing an amino alcohol structure like adrenergic drugs or β-blockers is described. The compounds are resolved on chiral ligand-exchange chromatography phases after derivatization with bromoacetic acid. © 1992 Wiley-Liss, Inc.
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    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040601
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    Optical isomers of a leukotriene b4 antagonist have differential effects on granulocyte diapedesis in the guinea pig dermis (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 353-355 
    Details
    ISSN: 0899-0042
    Keywords: leukotriene B4 ; SC-41930 ; dermis ; granulocyte ; stereoselectivity ; guinea pig ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Leukotriene B4 (LTB4) is a proinflammatory product of arachidonic acid metabolism that has been implicated in a number of inflammatory diseases. When injected intradermally into the guinea pig, LTB4 has been shown to elicit a dose-dependent infiltration of granulocytes as assessed by the level of the neutrophil marker enzyme myeloperoxidase. SC-41930 [7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid] is a potent LTB4 receptor antagonist. When compounds were coadministered along with LTB4 (35 ng) into the dermal site, racemic SC-41930, (+)-SC-41930, and (-)-SC-41930 each inhibited granulocyte accumulation with ED50 values of 340 ± 30, 98 ± 5.7, and 1000 ± 142 ng, respectively; when given intravenously inhibited with ED50 values of 0.5 ± 0.06, 0.3 ± 0.04, and 1.4 ± 0.19 mg/kg, respectively; and when given intragastrically inhibited with ED50 values of 1.7 ± 0.20, 1.4 ± 0.23, and 3.0 ± 0.41 mg/kg, respectively. © 1992 Wiley-Liss, Inc.
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    Stereoselective binding and activity of oxotremorine analogs at muscarinic receptors in rat brain (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 463-468 
    Details
    ISSN: 0899-0042
    Keywords: muscarinic receptors ; oxotremorine derivatives ; stereoselectivity ; adenylyl cyclase ; phosphoinositide metabolism ; receptor autoradiography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The activities of the enantiomers of BM-5 were examined to measure muscarinic cholinergic selectivity in the central nervous system. Autoradiographic studies assessed the ability of each enantiomer to inhibit the binding of [3H]-(R)-quinuclidinyl benzilate ([3H]-(R)-QNB) to muscarinic receptors in the rat brain. (+)-(R)-BM-5 inhibited [3H]-(R)-QNB binding to rat brain sections at concentrations below 1.0 μM, while 100-fold higher concentrations of ( - )-(S)-BM-5 were required for comparable levels of inhibition. Analysis of the autoradiograms indicated that both stereoisomers had a similar distribution of high affinity binding sites. Each enantiomer displayed higher affinity for muscarinic receptors in the superior colliculi and lower affinity for receptors in the cerebral cortex and hippocampus. (+)-(R)-BM-5 and oxotremorine inhibited adenylyl cyclase activity in the cerebral cortex with efficacies comparable to that for acetylcholine. (+)-(R)-BM-5 was 26-fold more potent than ( - )-(S)-BM-5 in inhibiting adenylyl cyclase. Oxotremorine-M and carbamylcholine stimulated phosphoinositide turnover in the cerebral cortex. Oxotremorine had lower activity and (+)-(R)-BM-5 was essentially inactive at comparable concentrations. The difference in activity of the two enantiomers indicates a remarkable stereochemical selectivity for muscarinic receptors. The stereoselectivity index is comparable for both the autoradiographic assays (48) and measures of adenylyl cyclase activity (26) in the cerebral cortex. © 1992 Wiley-Liss, Inc.
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    Measurement of the (R)- and (S)-isomers of warfarin in patients undergoing anticoagulant therapy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 488-493 
    Details
    ISSN: 0899-0042
    Keywords: achiral/chiral coupled HPLC ; α1-acid glycoprotein column ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An achiral/chiral high-performance liquid chromatographic system for the analysis of total warfarin together with the (R)- and (S)-enantiomers in clinical samples has been developed. The achiral analysis is achieved using a C8 column, which is coupled to a chiral stationary phase, α1-acid glycoprotein (AGP), thereby allowing for analysis of warfarin isomers without interfering serum peaks. A 0.015 M phosphate buffer mobile phase with 15% v/v propan-2-ol (pH 7.0) was used on the C8/AGP system. UV analysis at 308 nm was used for quantitation of total warfarin on the C8 column and fluorescence (excitation 300 nm, emission 390 nm) detection was employed for isomer quantitation on the AGP. Retention time of total warfarin on the C8 column was 5.95 min, while that of the (S)- and (R)-warfarin on the AGP column was 10.38 and 12.69 min, respectively. Peak resolution of the warfarin isomers was 1.64. All serum samples were subjected to solid-phase extraction. Data from two patients in a single dose study indicate that a two-compartmental model could represent the warfarin concentration - time data with enterohepatic circulation. In some patients studied during steady state therapy, concentrations of (S)-warfarin were greater than (R)-warfarin indicating that the clearance of the former is slower in these patients. © 1992 Wiley-Liss, Inc.
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    Announcement (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 521-521 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040811
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    The effects of (±)-, (+)-, and (-)-atenolol, sotalol, and amosulalol on the rat left atria and portal vein (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 8-14 
    Details
    ISSN: 0899-0042
    Keywords: (±)- ; (±)- ; (-)-atenolol ; sotalol ; amosulalol ; enantiomers ; β1 - and β2-adrenoceptors ; rat left atria and portal vein ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of (±)-, (+)-, and (-)-atenolol, sotalol, and amosulalol alone on the rat left atria and portal vein and on the respective β1- and β2-adrenoceptor-mediated responses to isoprenaline have been determined. (±)-Atenolol at 10-6 M had no effect whereas high concentrations of (+)- and (-)-sotalol, 10-5-10-4 M, and (±)-, (+)-, and (-)-amosulalol depressed the response of the rat left atria to cardiac stimulation which indicates membrane stabilizing activity. None of the drugs tested had any effect alone on the rat portal vein. The order of potency as antagonists was (±)-amosulalol 〉 (±)-atenolol 〉 (±)-sotalol at β1-adrenoceptors and (±)-amosulalol 〉 (±)-sotalol 〉 (±)-atenolol at β2-adrenoceptors. (±)-Atenolol and (±)-amosulalol are β1-selective whereas (±)-sotalol is β2-selective. For each of the racemic β-blockers, the β1- and β2-adrenoceptor blocking activity was predominantly due to the (-)-enantiomer. © 1993 Wiley-Liss, Inc.
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