Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1990-1994  (916)
  • 1955-1959
  • 1920-1924
  • 1992  (916)
  • Organic Chemistry  (916)
  • 1
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    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).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040307
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    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
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040407
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040411
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040502
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040504
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040114
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    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
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040604
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040603
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040609
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Announcement (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 406-406 
    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.530040614
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    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.530040701
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040705
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040310
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040408
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040409
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040510
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040512
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040802
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040806
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Resolution and stability of oxazepam enantiomers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 443-446 
    Details
    ISSN: 0899-0042
    Keywords: oxazepam ; chiral stationary phases ; high-performance liquid chromatography ; enantiomer separation ; enantiomer stability ; racemization ; kinetics of racemization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A solvent mixture containing dioxane, acetonitrile, and hexane was found to be suitable as a mobile phase to resolve oxazepam enantiomers by chiral stationary phase high performance liquid chromatography using covalent Pirkle columns. The resolved oxazepam enantiomers in this solvent mixture had a racemization half-life greater than 3 days at 23°C. When desiccated at 0°C as dried residue, OX enantiomers were stable for at least 50 days with less than 2% racemization. The conditions which stabilized OX enantiomers significantly facilitated the determination of racemization half-lives of OX enantiomers in a variety of aqueous and nonaqueous solvents and at different temperatures. © 1992 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040708
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    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.530040801
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Cytochrome p-455 nm complex formation in the metabolism of phenylalkylamines. XII. Enantioselectivity and temperature dependence in microsomes and reconstituted cytochrome p-450 systems from rat liver (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 469-477 
    Details
    ISSN: 0899-0042
    Keywords: metabolic intermediate (MI) complex ; amphetamine ; 1-phenyl-2-pentanamine ; N-hydroxyamphetamine ; 2-nitroso-1-phenylpropane ; P450 2B1 ; P450 2C11 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of metabolic intermediate (MI) complexes was studied with the enantiomers of amphetamine, 1-phenyl-2-pentanamine, N-hydroxyamphetamine, and 2-nitroso-1-phenylpropane (the C-nitroso analogue of amphetamine). Three different enzyme systems were used; liver microsomes from phenobarbital pretreated rats and two reconstituted systems containing the P450 2B1 and P450 2C11 forms of cytochrome P-450. Enantioselective complex formation in microsomes was shown for the amines and the nitroso compound, but not for the hydroxylamine. The highly purified P450 2B1 system formed the MI complex with all substrates tested, and the enantioselectivity observed with the microsomal system was reproduced. In the P450 2C11 system the nitroso compounds were completely inactive, whereas the enantiomers of N-hydroxyamphetamine still produced the complex at a high rate. Changes in temperature were shown to affect (R)-2-nitroso-1-phenylpropane more than its enantiomer. Both enantiomers showed biphasic Arrhenius plots for MI complex formation in microsomes (breaks around 22°C), but the activation energies of the (R)-isomer were about five times higher than those of the (S)-isomer. A theory is presented which suggests different modes of interaction with the active site of P-450 to account for the different behaviour of the various substrates. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040803
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    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.530040101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Stereoselective aliphatic hydroxylation of 6-n-propylchromone-2-carboxylic acid by female Dutch rabbits (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 1-7 
    Details
    ISSN: 0899-0042
    Keywords: product enantioselectivity ; aliphatic hydroxylation ; 6-n-propylchromone carboxylic acid ; chiral HPLC ; chiral shift 1H-NMR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 6-n-Alkylchromone-2-carboxylic acids are metabolized solely by aliphatic oxidation. In the rabbit, the 6-n-propyl congener (PCCA) undergoes ω-1 hydroxylation exclusively. Following administration of PCCA to female Dutch rabbits (500 μmol/kg), some 77% of the dose was excreted in the urine, 41% as PCCA and 36% as 6-(2'-hydroxy-n-propyl)chromone-2-carboxylic acid. Since this metabolite is chiral, we have examined the stereochemistry of the excreted material. Diastereoisomeric (as camphanate and α-methoxy-α-(trifluoromethyl)phenylacetate esters) and direct chiral HPLC and chiral lanthanide shift NMR have each shown the S:R ratio of the excreted metabolite to be 76:24. When rabbits were dosed with the racemic metabolite, excretion of the compound was not stereoselective. The regio- and stereo-selectivity of the aliphatic hydroxylation of PCCA are thus reflections of the selectivities of the enzyme systems responsible for its formation and suggest PCCA to be an appropriate probe compound for the study of prochiral-chiral hydroxylations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Enantiospecificity of kappa receptors: Comparison of racemic compounds and active enantiomers in two novel series of kappa agonist analgesics (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 8-15 
    Details
    ISSN: 0899-0042
    Keywords: opioids ; piperidines ; 1,2,3,4-tetrahydroisoquinolines ; antinociception ; binding affinity ; QSAR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two novel series, Ia,b and IIa,b, of kappa opioid antinociceptive agents have recently been described. 2a,b,3a,b,c The biological activities of 16 racemic compounds and their corresponding (-) enantiomers are now compared in a battery of tests. Enantiomers of unsubstituted piperidines Ia were synthesized starting from S(-) pipecolic acid, whereas the enantiomerically pure substituted piperidines (Ib), tetrahydroisoquinolines (IIa), and thienopiperidines (IIb) were, in general, obtained after diastereomeric crystallization of the corresponding tartrate salts. The absolute stereochemistry of one representative enantiomer from series IIa was determined to be (1S) by X-ray crystallographic analysis. Antinociceptive activity in the mouse abdominal constriction and tail-flick tests following subcutaneous administration, and binding affinity for κ and μ receptors, were found to reside predominantly in the (-) enantiomers. Consequently, racemic compounds showed approximately half potency of the corresponding enantiomers. This potency difference was less clear after oral administration presumably due to small differences in bioavailability of the two corresponding enantiomers.For compounds with some affinity also for μ receptors (Ki 〈1,000 nM), the κ/μ selectivity was maintained within each enantiomeric pair, in contrast to results found for other κ agonists.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Chiral discriminations with cinchona alkaloids (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 43-49 
    Details
    ISSN: 0899-0042
    Keywords: chiral discrimination ; enantiomeric separation ; chiral solvating agents ; asymmetric synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Enantioselective chromatography of the antimalarial agents chloroquine, mefloquine, and enpiroline on a α1 -acid glycoprotein chiral stationary phase: Evidence for a multiple-site chiral recognition mechanism (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 30-35 
    Details
    ISSN: 0899-0042
    Keywords: chiral liquid chromatography ; α1 -acid glycoprotein ; antimalarial agents ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of mobile phase pH and dimethyloctylamine (DMOA) on the retention (k') and stereoselectivity (α) of antimalarial agents mefloquine, enpiroline, and chloroquine on the α1-acid glycoprotein chiral stationary phase (AGP-CSP) was investigated. An increase of k' with increasing pH was observed while the effect on α was a function of the solute. The magnitude and direction of changes induced by DMOA depended on pH and the structure of the solute.The results of this study are consistent with a change of the conformation of the AGP between pH 5 and 7. At pH 7, the effect of DMOA on mefloquine was relatively well described by a competitive displacement from one enantioselective site. The effect on chloroquine and enpiroline suggests a multiple-site mechanism in which both competitive and allosteric interactions are involved.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Preparation of α-substituted α-amino acids of high enantiomeric purity (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 302-307 
    Details
    ISSN: 0899-0042
    Keywords: hydantoin derivatives ; chiral isocyanates ; LC separation of diastereomers ; preparative LC separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic 5,5-dialkyl hydantoins derived from ketones are resolved by preparative liquid chromatography as the diastereomeric 1-carboxamide derivatives afforded by the reaction with optically pure configurationally known α-phenylethyl isocyanate. Hydrolysis of the resolved diastereomers affords α-substituted α-amino acids of high enantiomeric purity. The synthetic route is short, overall yields are high, and the absolute configuration of the amino acid enantiomers may be deduced from the chromatographic and NMR properties of the diastereomers. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040508
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Application of antibody-mediated extraction for the stereoselective determination of the active metabolite of loxoprofen in human and rat plasma (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 308-315 
    Details
    ISSN: 0899-0042
    Keywords: loxoprofen ; 2-arylpropionic acid ; active metabolite ; immobilized antibody column ; chiral hapten ; diastereomeric derivatization ; chiral inversion ; stereoselective ketone reduction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Antibody-mediated extraction followed by chiral high-performance liquid chromatography (HPLC) was applied to stereoselective determination in human and rat plasma of the active metabolite [(2S,1]R,2[S)-trans-alcohol] with three chiral centers of Loxoprofen, a 2-arylpropionic acid antiinflammatory agent after oral administration. Antiserum against the (1'R,2'S)-cyclopentanol moiety was obtained from a rabbit immunized with bovine serum albumin conjugate linked to the propionic acid moiety, in which another chiral center is located. Then, the immunoglobulin G purified by a protein A column was coupled to BrCN-activated Sepharose 4B. Plasma samples were applied to the immobilized antibody column. After washing the column to remove unrequired stereoisomers, a mixture of two diastereomers whose configurations were 1'R,2'S in the cyclopentanol moiety was extracted with 95% methanol. The solvent was evaporated and the residue was derivatized with (+)-(R)-1-(1-naphthyl)ethylamine as a chiral reagent to separate the diastereomers by HPLC. This combined analytical method showed the stereoselective metabolism of Loxoprofen in human, that is, 64% of the total amount of four trans-alcohol stereoisomers was in the 2S, 1'R,2'S form, which is the active metabolite. This phenomenon was also observed in rats given Loxoprofen and its (2S)- and (2R)-isomers, and is explained by stereoselective ketone reduction of Loxoprofen to the (1'R,2'S)-trans-alcohol and inversion from 2R to 2S in the propionic acid moiety. Antibody-mediated extraction should be a selective and simple clean-up method for determining haptens with complicated structures, combined with an appropriate analytical method. © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040509
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Editorial (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. i 
    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.530040102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Stereoselectivity at α-adrenoreceptor subtypes: observations with the enantiomers of WB 4101 separated through their amides of N-Tosyl-(S)-proline (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 16-20 
    Details
    ISSN: 0899-0042
    Keywords: optical resolution ; enantioselectivity ; chromatography ; dissociation constants ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a chromatographic method for the separation and determination of the optical purity of the enantiomers of WB 4101 [(±)-1], one of the most potent and selective α1-adrenoreceptor antagonists. (±)-1 was converted into the amide of N-tosyl-(S)-proline. The two diastereoisomers were separated on silica gel and analysed by HPLC reversed phase. The analytical method described is both accurate and sensitive and allows the optical purity to be determined at very low concentrations and to obtain WB 4101 enantiomers with a purity of more than 99.95%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Stereoselective effect of phenprocoumon enantiomers on the binding of benzodiazepines to human serum albumin (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 21-23 
    Details
    ISSN: 0899-0042
    Keywords: protein binding ; affinity chromatography ; resolution ; allosteric interaction ; increased enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of phenprocoumon enantiomers on the stereoselective binding of 3-substituted 1,4-benzodiazepines to human serum albumin (HSA) was studied by chromatography on HSA-Sepharose column. (S)-Phenprocoumon exerts stereoselective allosteric interaction on the binding of benzodiazepines. The structural requirements of enhanced stereoselectivities are similar to those found previously with (S)-warfarin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Improvement of the enantiorecognition ability of tyrosine-derived chiral stationary phases: Direct resolution of 1,2-amino-alcohols (β-blockers) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 36-42 
    Details
    ISSN: 0899-0042
    Keywords: tyrosine chiral selector ; enantiomeric separations ; chiral stationary phases ; HPLC ; subFC ; β-blockers ; 1,2-amino-alcohols ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel chiral stationary phase (CSP) derived from tyrosine is evaluated with regard to the first generation commercially available (S)-ChyRoSine-A CSP, under normalphase or reversed-phase liquid chromatographic (NPLC or RPLC) and subcritical fluid chromatographic (SubFC) conditions. The complete scope of application of these CSPs is reviewed. The novel CSP, which bears a bulkier functional group, displays a higher enantiorecognition ability than previously described (S)-ChyRoSine-A toward about 15 families of racemates, whatever the mobile phase conditions.The direct enantiomeric separation of 1,2-amino-alcohols (β-blockers) is carried out on both CSPs. Facile separations are achieved within short analysis times using SubFC mode, whereas very poor separations are obtained using NPLC mode. These results disagree with previous theories (interchangeability between NPLC and SubFC modes).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Use of cyclodextrins in capillary zone electrophoresis for the separation of optical isomers: Resolution of racemic tryptophan derivatives (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 56-61 
    Details
    ISSN: 0899-0042
    Keywords: capillary zone electrophoresis ; enantiomers ; cyclodextrins ; tryptophan derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this study capillary zone electrophoresis has been used for the separation of racemic tryptophan derivatives in their enantiomers. The effect of cyclodextrins with different shape, added to the background electrolyte, on the migration time of 10 compounds, including methyl tryptophan, hydroxy tryptophan, and tryptophan ester derivatives, has been studied. Furthermore, the effect of cyclodextrins with different shape and that of the composition of the background electrolyte on the enantiomer resolution are discussed. Among different cyclodextrins used α-cyclodextrin and heptakis(2,6-di-O-methyl)-β-cyclodextrin were found to possess the best complexing capacity and thus the resolution power toward analysed compounds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Letter to the editors: Rootworm pheromones: The root of a stereochemical mixup (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 68-70 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040115
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    The influence of aging on the stereoselective pharmacokinetics of propranolol in the rat (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 73-79 
    Details
    ISSN: 0899-0042
    Keywords: aging ; β-adrenergic blocking agent ; enantiomers ; propranolol ; protein binding ; stereoselective pharmacokinetics ; tissue binding ; tissue concentrations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of aging on the pharmacokinetics and the tissue distribution of (R)- and of (S)-propranolol was studied in 3-, 12-, and 24-month-old rats. After both iv and oral administration of rac-propranolol, the plasma concentrations were higher for the (R)- than for the (S)-enantiomer. For the tissue concentrations, the reverse was true. The free fraction of (S)-propranolol in plasma was about 4 times larger than that of (R)-propranolol, and this is the main factor responsible for the differences in kinetics between the two enantiomers. There was a suggestion for a difference in tissue binding between the two enantiomers. With aging, the plasma and tissue concentrations of both enantiomers increase, probably due to a decrease in blood clearance. Tissue binding did not change much with aging. Notwithstanding the marked differences between the kinetics of the propranolol enantiomers, the changes which occur with aging affect both enantiomers to the same degree.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    The disposition of venlafaxine enantiomers in dogs, rats, and humans receiving venlafaxine (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 84-90 
    Details
    ISSN: 0899-0042
    Keywords: high-performance liquid chromatography (HPLC) ; chiral assay ; naproxen chloride ; pharmacokinetics ; racemate ; stereoselective ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A stereospecific high-performance liquid chromatographic (HPLC) method was developed for the quantitation of the enantiomers of venlafaxine, an antidepressant, in dog, rat, and human plasma. The procedure involves derivatization of venlafaxine with the chiral reagent, (+)-S-naproxen chloride, and a postderivatization procedure. The method was linear in the range of 50 to 5,000 ng of each enantiomer per ml of plasma. No interference by endogenous substances or known metabolites of venlafaxine occurred. Studies to characterize the disposition of the enantiomers of venlafaxine were conducted in dog, rat, and human, following oral administration of venlafaxine. The Cmax, area under the curve (AUC) and (S)/(R) concentration ratios of the (R)- and (S)-enantiomers were compared. In rats, the mean plasma ratio of (S)-venlafaxine to that of (R)-venlafaxine over 0.5 to 6.0 h varied from 2.97 to 8.50 with a mean value of 5.51 ± 2.45. The Cmax, AUC0 - ∞, and t1/2 values of the (R)- and (S)-enantiomers in dogs were not significantly different from one another (P〉0.1). The mean ratios [(S)/(R)] of enantiomers of venlafaxine in human over a 2 to 6 h interval ranged from 1.33 to 1.35 with an overall ratio of 1.34 ± 0.26 (n = 12). These ratios of the enantiomers [(S)/(R)] were not statistically different from unity (P〉0.1) indicating that the disposition of venlafaxine enantiomers in humans is not stereoselective and is more similar to that in dogs than that in rats.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Unusual amino acids I: Asymmetric synthesis of furylalanine derivatives (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 110-115 
    Details
    ISSN: 0899-0042
    Keywords: furyldehydroamino acid ; enantioselectivity ; hydrogenation ; chiral rhodium complexes ; amino-phosphine-phosphinite ; ligands enantiomers ; (R)- and (S)-isomers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nonproteinogenic amino acids are valuable active compounds from their pharmacological and biochemical effects and also as novel building blocks for peptides. The preparation of furylalanine derivatives by asymmetric hydrogenation is described. Amino-phosphine-phosphinite-rhodium complexes catalyzed the hydrogenation of the prochiral dehydroamino acid precursors in high rate and with enantioselectivities of 70 - 90% ee. Substrate-catalyst ratios up to 2,000 can be used depending on the catalyst applied. The procedure turns out to be suitable for larger scale preparations.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Effective methods for enantioselective analysis of glycidol derivatives by liquid chromatography (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 132-135 
    Details
    ISSN: 0899-0042
    Keywords: sharpless asymmetric epoxidation ; chiral epoxide ; carbamate ; tin(IV) ; catalysis ; 4-hydroxy-2,3-epoxybutyrates ; Chiralcel OD ; Chiralcel® OB ; Zorbax® NH2 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methodology for determination of the enantiomeric purity of sixteen 2,3-epoxy-1-propanols (glycidols) is delineated. Conversion of these epoxy alcohols and 1-naphthyl isocyanate (NIC) into the 1-naphthyl carbamates is catalyzed by dibutyltin diacetate. Enantiomers of these carbamates are resolved on a Chiralcel® OD column. Advantages of this method include mildness of reaction conditions, nonreliance on diastereomeric derivatization, and appendage of a UV-absorbing chromophore to the analyte.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040212
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    The effect of the enantiomers of ibuprofen and flurbiprofen on the β-oxidation of palmitate in the rat (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 137-141 
    Details
    ISSN: 0899-0042
    Keywords: 2-arylpropionic acids ; nonsteroidal antiinflammatory drugs ; stereoselective ; coenzyme A thioesters ; chiral inversion ; oxidative phosphorylation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of the enantiomers of ibuprofen (0.25 and 0.50 mmol/kg b.w.) and flurbiprofen (0.01, 0.03, and 0.06 mmol/kg b.w.) on the β-oxidation of palmitate were investigated in the rat. The mean cumulative exhalation of 14CO2 after ip administration of [U-14C]palmitic acid was significantly reduced over 6 h by ibuprofen at the higher dose but not at the lower dose for either enantiomer. There was no difference between the enantiomers, the reduction over 6 h being 31.3 and 33.0% for (R)- and (S)-ibuprofen, respectively. There was also a significant inhibition of β-oxidation by flurbiprofen at all 3 doses. Again, there was no stereoselectivity evident in this inhibition. Flurbiprofen was much more potent than ibuprofen in eliciting this effect, the 0.01mmol/kg dose giving a similar reduction in β-oxidation as observed for the 0.50 mmol/kg dose of ibuprofen. The data support the hypothesis that inhibition of the in vivo β-oxidation of palmitate by ibuprofen and flurbiprofen is primarily via a nonstereoselective noncoenzyme A-dependent mechanism. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Enantioselective pharmacokinetics of ethotoin in humans following single oral doses of the racemate (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 142-147 
    Details
    ISSN: 0899-0042
    Keywords: anticonvulsants ; epilepsy ; stereoisomers ; hydantoins ; metabolism ; HPLC assay ; chiral columns ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic ethotoin (1000 mg) was administered orally as a single dose to six healthy adult volunteers. Blood samples were collected at appropriate times for 120 h following the dose. Ethotoin was quantified enantioselectively in plasma using a novel chiral column HPLC procedure. One of the enantiomers of the chiral metabolite, 5-phenylhydantoin, was also quantified in the HPLC method. The Cmax and AUC0 - ∞ values for (+)-(S)-ethotoin were significantly greater than those for ( - )-(R)-ethotoin (ratio of mean AUC0 - ∞ values 0.88), but the elimination half-lives of the isomers were virtually identical [12.35 ± 5.15 h for ( - )-(R)-thotoin; 12.28 ± 5.34 h for (+)-(S)-ethotoin]. Parameters derived from AUC0 - ∞ (Cl0/F and Varea/F) also differed slightly between the isomers. The data were interpreted as indicating a small difference in the absorption of the two isomers; it seemed unlikely, in terms of the identical elimination rates, that their metabolic profiles would differ greatly. The 5-phenyl-hydantoin was eliminated with a significantly longer half-life (18.69 ± 6.11 h) than that of ethotoin. Enantioselectivity in the pharmacokinetics of ethotoin is therefore a minor issue. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Chiroptical detection during liquid chromatographyPart 4. For Part 3, see Ref. 1.: Applications to stereoanalysis and stereodynamics (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 163-169 
    Details
    ISSN: 0899-0042
    Keywords: polarimetry ; circular dichroism spectra ; optical purity ; thermal interconversion of enantiomers ; optically active sorbents ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Qualitative and quantitative use of polarimetry at one wavelength for detection during liquid chromatography is briefly reviewed. Acquisition of circular dichroism spectra by stopped-flow and nonstop measurements has been further developed. Reasons are given why the angle of rotation, i.e., the polarimeter, is preferred for monochromatic use and differential absorbance, i.e., the dichrograph, for polychromatic requirements. Both methods are demonstrated by novel applications, mainly to enantiomers which interconvert thermally via intramolecular processes. © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040306
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Enantio- and regioselectivity in the epoxide-hydrolase-catalyzed ring opening of simple aliphatic oxiranes: Part I: Monoalkylsubstituted oxiranes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 178-184 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective hydrolysis ; regioselective hydrolysis ; epoxide hydrolase ; substrate enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in vitro conversion of chiral aliphatic monoalkylsubstituted oxiranes into 1,2-diols catalyzed by epoxide hydrolase of rat liver microsomes occurs with substrate enantioselectivity and regioselectivity. Substrate enantioselectivity is generally low, and has the same sense, for methyloxirane, vinyloxirane, epichloro-, and epibromohydrin. In the hydrolysis of t-butyloxirane inhibitory effects are involved leading to a complex pattern of enantioselectivity. All investigated monosubstituted aliphatic oxiranes are hydrolyzed with high regioselectivity by nucleophilic attack of water at the unsubstituted ring carbon atom. The enantiomeric excess of the unreacted oxirane substrates and the diol metabolites formed were determined by complexation and inclusion gas chromatography. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Separation of enantiomeric amines and acids using chiral ion-pair chromatography on porous graphitic carbon (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 323-332 
    Details
    ISSN: 0899-0042
    Keywords: chiral separation ; chiral counterion ; ion-pair chromatography ; N-benzyloxycarbonylglycyl-L-proline ; quinine ; indirect detection ; porous graphitic carbon ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of porous graphitic carbon as adsorbing phase for direct separation of enantiomeric acids and amines using chiral ion-pair chromatography is described. The enantiomeric amines were separated as diastereomeric ion pairs with N-benzyloxycarbonylglycyl-L-proline, N-benzyloxycarbonylglycylglycyl-L-proline, or captopril as the chiral counterion. High enantioselectivities were obtained for amines having a hydrogen bonding function in the vicinity of the asymmetrical carbon atom. Quinine was the chiral counterion used to separate the enantiomeric acids. The strongly UV-absorbing quinine improved detection of solutes having low UV-absorbing properties, e.g., (R,S)-2-chloropropionic acid, by “indirect detection.” Retention and stereoselectivity of enanticmeric acids were regulated by the quinine concentration and by the addition of carboxylic acids as well as polar modifiers, e.g., methanol and 2-propanol, to the mobile phase. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040511
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Editorial: Chirality receives award from the association of american publishers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 341-341 
    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.530040602
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Chiral hplc-cd studies of the antituberculosis drug (+)-ethambutolPresented 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. 227-229 
    Details
    ISSN: 0899-0042
    Keywords: circular dichroism ; exciton coupling ; derivatisation ; tetrabenzoylethambutol ; dibenzoyl-2-aminobutan-1-ol ; absolute stereochemistry ; Pirkle column ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Long standing errors in major pharmacopoeiae (BP,USP, and Eu.Ph.) concerning the absolute stereochemistry of the widely used antituberculosis drug (+)-ethambutol have been clarified by unambiguous synthesis and chiral HPLC. on a Pirkle, covalent D-phenylglycine column of perbenzoyl derivatives of each stereomer; the enantiomeric (-)-(R,R) and (+)-(S,S)-ethambutols together with the optically inactive (meso)-(R,S)-ethambutol. This paper describes how circular dichroism (CD) alone and combined with HPLC is used to demonstrate this chiral separation and also to confirm the absolute stereochemistry of each stereomer of ethambutol and its synthetic precursor 2-aminobutan-1-ol from studies of „exciton coupling.“ The strengths and weaknesses of these chiral techniques are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Chirality evaluation in flavour and essential oil analysis (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 50-55 
    Details
    ISSN: 0899-0042
    Keywords: simultaneous stereodifferentiation of γ(δ)-lactones ; chiral monoterpenes ; stereoselective analysis ; modified cyclodextrins ; genuineness of flavours and essential oils ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simultaneous stereodifferentiation of all aromarelevant 4(5) alkylsubstituted γ(δ)-lactones is described, using enantioselective multidimensional gas chromatography (MDG), and the column combination OV 1701/octakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin. The method is applicated to the lactone flavour compounds of fruits, indicating the advance to the analytical differentiation between “natural” and “nature-identical” aromas. Modified cyclodextrins are also proved to be powerful tools in the chirospecific CGC analysis of monoterpenoid constituents of essential oils. Optical purity control is discussed as an indicator for their natural origin.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Determination of the enantiomeric purity of (--) 2-(N-propyl-n-2-thienylethylamino)-5-hydroxytetralin (n-0923) by chiral stationary phase HPLC (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 62-64 
    Details
    ISSN: 0899-0042
    Keywords: dopamine agonist ; direct chiral separation ; cellulose carbamate stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of the enantiomeric impurity, i.e., the percentage of (+) N-0437 (= N-0924) in several batches of (--) N-0437 (= N-0923) by chiral HPLC is described. Enantiomeric impurities were calculated based on the peak areas of the two baseline separated enantiomers in the chromatogram. The enantiomeric impurities found in different batches ranged from 0.02% to 0.11%. Calibration curves of the two isomers of N-0437 (Fig. 1,) were made twice to study the reproducibility and linearity of the method. The absorbance ratio, N-0923/N-0924, was found to be 1.02 with a relative standard deviation (RSD) of 9% over the whole concentration range used for the calibration curves.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040113
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    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.530040201
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Optically-Active compounds via biocatalytic methodsSecond International Symposium on Chiral Discrimination, May 27 - 31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 91-97 
    Details
    ISSN: 0899-0042
    Keywords: improving enantioselectivity ; lipase ; enantioselective biocatalysis ; enantiomerically pure compounds ; dihydropyridines ; enantioselective inhibition ; cis-3-hydroxy-6-acetoxy-cyclohex-1-ene ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Different approaches to improve the enantioselectivity of biocatalytic systems are presented. These methodologies have been successfully applied to the preparation of optically active dihydropyridine, calcium antagonists, and cis-3-hydroxy-6-acetoxy-cyclohex-1-ene, a valuable chiral building block for natural products synthesis. The phenomenon of enantioselective inhibition is described and several new heterocyclic amines have been shown to be effective enantioselective inhibitors in the Candida lipase system.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    FDA'S policy statement for the development of new stereoisomeric drugs (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 338-340 
    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.530040513
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Stereoselective biliary elimination of disopyramide and mono-N-desisopropyldisopyramide in humansPresented at the Second International Symposium of Chiral Discrimination, May 23 - 31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 80-83 
    Details
    ISSN: 0899-0042
    Keywords: disopyramide ; enantiomers ; clearance ; bile ; metabolism ; humans ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results of a previous pharmacokinetic study of disopyramide (DP) enantiomers in humans suggested that DP and/or mono-N-desisopropyldisopyramide (MND) may show stereoselective extrarenal elimination. Thus, the present study investigates the biliary elimination of DP and MND enantiomers in three patients who had undergone cholecystectomy for cholelithiasis. DP and MND enantiomers displayed biliary elimination. In both subjects, this elimination pathway showed the same characteristics: (1) biliary elimination of DP and MND was stereoselective, (2) the stereoselectivity was opposite to that observed for the metabolic and renal elimination pathways, i.e., the elimination of the (-)-(R)-enantiomer was higher than that of the (+)-(S)-enantiomer, and (3) biliary elimination of MND was higher than that of DP, for both enantiomers. Estimates of the relative contribution of the biliary clearance in the total clearance of DP and MND indicated that this elimination pathway was secondary, especially for DP. The biliary clearance (expressed as % of total clearance) was 1.9 to 4.0% for (-)-(R)-DP, 1.2 to 1.7% for (+)-(S)-DP, 7.8 to 22.9% for (-)-(R)-MND, and 5.2 to 10.5% for (+)-(S)-MND.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Plasma determination of the enantiomers of SL 84.0418, a new antihyperglycaemic drug, by HPLC on a chiral α1-agp columnSecond International Symposium on Chiral Discrimination, May 27 - 31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 116-121 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: SL 84.0418 is a new antihyperglycaemic drug. It is an orally active and selective α2-adrenoceptor antagonist. This molecule, a pyrroloindole derivative, contains an asymmetric center yielding two enantiomers. In order to evaluate the pharmacokinetic profile of both enantiomers following oral administration of the racemate we have developed an HPLC method for their separation and quantification. The liquid - liquid extraction involved three steps with two salting-out procedures at pH 11.5 before and after a back-extraction with 0.005 M H2SO4. The enantiomers were separated by HPLC on a stainless-steel column (100 x 4.0 mm) packed with a chiral α1 -acid. The UV response was linear from 1 to 250 ng/ml for both enantiomers. The relative standard deviation (RSD) for reproducibility was below 10.7%. Using quality control samples, precision was found below 7.8% and accuracy was 108%. Extraction recoveries were ca. 60% for both enantiomers and 94% for the internal standard. Column life was brought up to 2 months, which corresponds to about 1,000 injections of biological extract. No guard column was used, but a daily back-flush was carried out. This method is suitable for routine analysis and 30 to 40 plasma samples a day can be processed. This method allows the definition of the pharmacokinetic profile of both enantiomers of SL 84.0418 in human plasma after single oral administration of doses as low as 20 mg of the racemic drug.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    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.530040301
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    The resolution, isolation, and pharmacological characterization of the enantiomers of a benzamide containing a chiral sulfoxide (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 155-162 
    Details
    ISSN: 0899-0042
    Keywords: gastroprokinetic ; serotonin receptors ; 5-HT3 receptors ; guinea pig ileum ; single-crystal X-ray ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rac-ML-1035 (MDL 201,035: 4-amino-5-chloro-2-[2-(methylsulfinyl)ethoxy] -  N-[2-(diethylamino)ethyl] benzamide hydrochloride) is a racemic gastroprokinetic with serotonergic (5-hydroxytryptamine, 5-HT) activity and a novel chiral sulfoxide substituent. Chromatographic and chemical methods have been developed to resolve the enantiomers of rac-ML-1035, and the absolute configuration of the (R)-enantiomer has been determined. We also report pharmacological characterization of rac-ML-1035 and its respective isomers. Radioligand binding to rat cortical membranes revealed that (R)-ML-1035 (MDL 201,226) and (S)-ML-1035 (MDL 201,227) had equivalent activity at the 5-HT3 receptor. However, in isolated tissue studies including field-stimulated guinea pig ileum, field-stimulated rat fundic strip, and nonstimulated guinea pig ileum, (S)-ML-1035 was equally potent yet had greater maximal activity than (R)-ML-1035 in eliciting or facilitating cholinergic contractions. Thus, enantiomers of rac-ML-1035 can be resolved, and the relative configuration of these isomers influences their pharmacological activity. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Chromatographic resolution of the chiral isomers of several β-blockers over cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 174-177 
    Details
    ISSN: 0899-0042
    Keywords: chiral resolution ; β-blockers ; HPLC ; cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical resolution of seven β-blockers which have in common the N-isopropyl-3-aryloxy-2-hydroxypropylamine moiety was carried out by HPLC using the cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase to quantitatively characterize the enantioselectivity of these compounds. The capacity factors and separation factors at different column temperature were determined with some qualitative trends derived. A compensation effect was observed for these compounds where there exists an approximately linear relationship between the enantiomeric differences in enthalpic and entropic energies. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040308
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Chiral α-substituted α-aryloxy acetic acids: Synthesis, absolute configuration, chemical resolution, and direct separation by hplc (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 193-203 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; chiral phase ; chiral recognition ; aryloxyacetic acids ; optical rotatory dispersion ; circular dichroism ; biological stereospecificity ; myotonia ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several α-monoalkyl-α-aryloxyacetic acids have been synthesized and resolved into their optical antipodes; their absolute configuration was also established by chiroptical and chemical methods. The two enantiomers of a series of these compounds show opposite effects on skeletal muscle fibers chloride conductance. Therefore a HPLC procedure was developed for the direct determination of the optical purity of the antipodes before submitting them to biological tests. The chromatographic study was performed on DACH-DNB chiral stationary phase which shows a remarkable enantioselectivity for the considered compounds as free acids, esters and amides under different conditions with essentially the same chiral mechanism of separation. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040311
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Enantioselectivity in the induction of peroxisome proliferation by 2-ethylhexanoic acid (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 478-483 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; nonchiral chromatography ; palmitoyl coenzyme A oxidation ; plasticizer ; rat hepatocytes primary culture ; racemate ; resolution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoselectivity of the peroxisome proliferation potency of 2-ethylhexanoic acid (2-EHA), a metabolite of the plasticizer di-(2-ethylhexyl) adipate, was investigated in vitro. The enantiomers of 2-EHA were prepared via the semipreparative HPLC resolution of their diastereoisomeric (+)-(R)-1-phenylethylamine derivatives and the subsequent hydrolytic cleavage. Monolayers of hepatocytes were incubated 3 days with solutions of ( - )-(R), (+)-(S), and (±)-2-EHA. The peroxisome proliferation potency was measured by means of determination of the peroxisomal palmitoyl coenzyme A oxidation. The theoretical induction component due to each enantiomer were calculated from the experimental data considering the enantiomeric purities of the acids. The (+)-(S)-enantiomer was found to be the most potent inducer, e.g., the eutomer, while the ( - )-(R) was the distomer. The eudismic ratio was about 1.6 and the racemic mixture exhibited an intermediary potency. These results, obtained in vitro in conditions avoiding confounding factors such as pharmacokinetics, suggest that the peroxisome proliferation induced by 2-ethylhexanoic acid is a stereoselective phenomenon. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040804
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Enantioselective pharmacodynamics of the nonsteroidal antiinflammatory drug ketoprofen: In vitro inhibition of human platelet cyclooxygenase activity (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 484-487 
    Details
    ISSN: 0899-0042
    Keywords: ketoprofen enantiomers ; thromboxane ; in vitro activity ; 2-arylpropanoic acids ; sigmoidal Emax modelling ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pharmacological activity of ketoprofen enantiomers was investigated in humans by an in vitro method. The antiplatelet effect of ketoprofen was assessed by measuring the inhibition of platelet thromboxane B2 (TXB2) generation during the controlled clotting of whole blood obtained from each of four healthy volunteers. Ketoprofen was added separately to whole blood as a range of concentrations of (1) predominantly (S)-ketoprofen, (2) racemic ketoprofen, and (3) predominantly (R)-ketoprofen. (S)-Ketoprofen was found to be solely active at inhibiting human platelet TXB2 production; (R)-ketoprofen was devoid of such activity and did not modify the potency of its optical antipode. A relationship between the percentage inhibition of TXB2 generation and the unbound concentration of (S)-ketoprofen in serum was modelled according to a sigmoidal Emax equation. The mean (±SD) serum unbound concentration of (S)-ketoprofen required to inhibit platelet TXB2 generation by 50% (EC50) was 0.320 (±0.062) ng/ml. This value for ketoprofen is considerably lower than previously reported values for (S)-ibuprofen and (S)-naproxen. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    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.530040501
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Stereospecific gas chromatographic method for determination of methadone in serumPresented at the Second International Symposium on Chiral Discrimination, May 27-31, 1991, Rome, Itlay.This work was performed at the Department of Clinical Chemistry, Bispebjerg Hospital. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 263-267 
    Details
    ISSN: 0899-0042
    Keywords: methadone ; GC ; (-)-menthylchloroformate ; derivatization ; stereospecific ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: rac-Methadone is used clinically for the chronic maintenance treatment of heroin addiction and for the relief of pain. As the pharmacological activity of methadone is due primarily to the (-)-(R)-enantiomer, stereospecific measurements of methadone serum concentrations in methadone-treated patients are expected to be more relevant for clinical studies than earlier described total drug measurements. This study describes a stereospecific gas chromatographic (GC) method for the determination of methadone in serum. The extracted methadone was derivatizised with (-)-menthyl chloroformate. The diastereometric derivatives were analysed by GC on a capillary column and detected with a nitrogen-phosphorus detector. The resolution factor obtained for the methadone enantiomers was 1.1 with a relatively short time of analysis (30 min). By analysing the pure (-)-(R)-enantiomer, no racemization was seen during the analysis. The lower limit of quantitation was 75 nmol/1 for each enantiomer. Measurements of the ratio between (-)-(R)- and (+)-(S)-methadone concentrations in serum from five methadone-treated patients showed interindividual differences (range 0.5-1.1). The patient results correlated well with those from another GC method measuring total methadone.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040410
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Short and simple synthesis of (R)- and (S)-4-hydroxypentylaminoacetamide: both enantiomers of the (ω-1)-hydroxylated metabolite of milacemideThis paper was presented at the Second Chiral Discrimination meeting, May 27-31, 1991, Rome, Italy. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 286-294 
    Details
    ISSN: 0899-0042
    Keywords: milacemide ; metabolites ; enantiomers ; hydroxylation ; cytochrome P-450 ; γ-valerolactone ; enzymic kinetic resolution ; 1H-NMR shift reagent ; (-)-(1S)-camphanyl diastereomeric derivatives ; solid solution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both (R)- and (S)-4-hydroxypentylaminoacetamide have been synthesized by reductive amination of glycinamide on the γ-valerolactols corresponding to (R)- and (S)-γ-valerolactone, respectively. These enantiomeric lactones were readily obtained in high enantiomeric excess (ee) by enzymic porcine pancreatic lipase (PPL) kinetic resolution of rac-methyl γ-hydroxyvalerate. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040505
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Stereochemical studies of chiral h-1 antagonists of histamine: The resolution, chiral analysis, and biological evaluation of four antipodal pairs (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 356-366 
    Details
    ISSN: 0899-0042
    Keywords: H-1 antihistamines ; chiral HPLC ; β-cyclodextrin-inclusion complexes ; NMR ; circular dichroism ; affinity constants ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The resolution of the H-1 antihistamines chloropheniramine, dimethindene, carbinoxamine, and mebrophenhydramine is described. The optical purity of antipodal products is investigated by chiral HPLC (use of α1 -acid glycoprotein and β-cyclodextrin columns) and NMR (spectra of β-cyclodextrin inclusion complexes). Configurational relationships among the group are reviewed and assignments are confirmed and extended by circular dichroism evidence. Affinity constants of antipodal pairs for guinea pig ileum and cerebellum sites, determined by gut bath and binding experiments respectively, are reported together with some in vivo tests in man for central effects. Results are discussed in terms of configurational requirements for activity and variations in antipodal potency ratios within the group. © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040606
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Absolute configuration and conformation of the pure opioid antagonist (+)-2,9α-dimethyl-5-(m-hydroxyphenyl)morphan (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 377-383 
    Details
    ISSN: 0899-0042
    Keywords: crystal structure ; molecular mechanics ; MM2-87 ; phenylmorphan ; phenyl-equatorial ; opioid ligand model ; μ-receptors ; K-receptors ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-2,9α-Dimethyl-5-(m-hydroxyphenyl)morphan is the only phenylmorphan analog whose affinity for opioid K-receptors is greater than its affinity for opioid κ-receptors. Pharmacologically, the compound is a pure opioid antagonist devoid of agonist activity in in vivo assays of antinociception. The absolute configuration of the compound has been determined to be (1R,5S,9R) from an X-ray crystallographic study of the chloride salt. Thus, the absolute configuration corresponds to that of the atypical opioid agonist (-)-phenylmorphan while the weak atypical agonist (-)-2,9α-dimethyl-5-(m-hydroxyphenyl)morphan corresponds to the potent morphine-like (+)-phenylmorphan. The preferred orientations of the phenyl ring for the two stereoisomers were determined using the molecular mechanics program MM2-87 and found to vary from that of the two parent compounds. The atypical properties of the two 9α-methyl analogs is consistent with an opioid ligand model which proposes that morphine-like properties require a particular range of phenyl orientations. There was good agreement between the structure obtained from X-ray crystallography and computed with the MM2-87 program. © 1992 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040608
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Strategy combining chiral chromatography with β-cyclodextrin and stereospecific enzyme reaction detection with hydroxysteroid dehydrogenases for resolving steroid epimers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 395-399 
    Details
    ISSN: 0899-0042
    Keywords: chiral chromatography ; steroids ; androstanediolepimers ; androsteroneepimers ; β-cyclodextrin complexation ; hydrosteroid dehydrogenase ; postcolumn enzyme detection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steroids are chiral molecules with multiple stereogenic centers. Studies of their intermediary metabolism often require analytical techniques to separate the isomers and determine their stereochemistry. Methods for resolving steroid stereoisomers by HPLC using β-cyclodextrin in the mobile phase are reported. Even with the improved selectivity of cyclodextrin chromatography, not all isomers within a steroid series can be resolved. Additional specificity is achieved by reaction detection using postcolumn reactors containing hydroxysteroid dehydrogenases stereospecific for the configuration of the hydroxy functions of steroids. The enzymes catalyze the oxidation of hydroxysteroids and reduction of the coenzyme NAD to NADH. NADH, which is highly fluorescent, is detected at the nanogram levels. Isomers not separated by chromatography were effectively resolved by reaction detection with stereospecific enzymes. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040611
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Preparative resolution of some 5,5-hydantoin derivatives via formation of diastereoisomeric saltsThis 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. 400-403 
    Details
    ISSN: 0899-0042
    Keywords: solvent ; basic medium ; competitive solubilities ; optimization ; optical resolution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several preparative resolutions of 5,5-disubstituted hydantoins have been achieved via fractional crystallization of diastereoisomeric salts. The process can be extended by making use of the difference between the variation of solubilities of the hydantoins and their salts with α-methylbenzylamine as a function of the alkalinity of the medium. Optimization for each resolution procedure involves a refinement of the excess amount of base needed. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040612
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Glutathione conjugation and pharmacokinetics of 2-bromo-3-phenylpropionic acid in vitro and in the rat in vivo (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 407-414 
    Details
    ISSN: 0899-0042
    Keywords: GSH conjugate ; pharmacokinetics ; biliary excretion ; chiral ; 2-bromo-3-phenyl propionic acid ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glutathione (GSH) conjugation of the chiral compound 2-bromo-3-phenylpropionic acid (BPP) was studied in vitro and in the rat in vivo. GSH conjugation of BPP, catalyzed by a mixture of glutathione-S-transferases (GST's) from rat liver cytosol in vitro, was stereoselective: at a substrate concentration of 250 μM, (R)-BPP was more rapidly conjugated than (S)-BPP (R/S-ratio = 2.6). The blood elimination kinetics of the separate BPP enantiomers and the biliary excretion kinetics of the corresponding GSH conjugates were studied in the rat in vivo after administration of (R)- or (S)-BPP at a dose level of 50 μmol/kg. Elimination of (R)-BPP from blood was faster than that of (S)-BPP: half lives were 9 ± 2 min for (R)-BPP and 13 ± 1 min for (S)-BPP. The biliary excretion rate of the GSH conjugate of (R)-BPP declined monoexponentially, while that of the GSH conjugate of (S)-BPP displayed a biphasic profile. Half lives of excretion were 13 ± 1 for the GSH conjugate of (R)-BPP, and 11 ± 2 for the GSH conjugate of (S)-BPP (second phase). The first phase in the biliary excretion of the GSH conjugate of (S)-BPP could not be attributed to capacity limitation of biliary transport carriers as higher excretion rates were attained upon administration of higher doses (100 and 200 μmol/kg) of ((S)-BPP). The blood elimination profiles of (R)- and (S)-BPP differed greatly from the biliary excretion profiles of the corresponding GSH conjugates. This suggests that the kinetics of BPP conjugate excretion are determined by other processes than hepatic GSH conjugation. © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040702
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Improved resolution of (±)-trans-2'-hydroxy-5,9-dimethyl-6,7-benzomorphans (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 439-442 
    Details
    ISSN: 0899-0042
    Keywords: trans-nor-pentazocine ; Sigma ; PCP ; NMR analysis ; GC analysis ; chiral derivatizing reagents ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient resolution of (±)-trans-2'-hydroxy-5,9-dimethyl-6,7-benzomorphan has been developed employing ( - )-(R)- and (+)-(S)-O-acetylmandelic acids. Measurement of optical rotations on the resolved bases, NMR analyses of diastereomeric urea derivatives, as well as gas chromatographic analyses of diastereomeric amide derivatives indicate a net improvement over previous resolution methodology and an enantiomeric excess ≥ 99%. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Chromatographic optical resolution on trans-1,2-diaminocyclohexane derivatives: Theory and applicationsPresented 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. 447-458 
    Details
    ISSN: 0899-0042
    Keywords: enantioseparation ; reverse-phase chiral HPLC ; organic-inorganic chiral stationary phases ; polymeric CSPs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An overall view on some new chiral stationary phases based on (trans)-1,2-diaminocyclohexane is illustrated. The selected chiral moiety, derivatized with different aroyl groups, has been linked to a silica matrix in order to give chiral stationary phases (CSPs) enabling them to be used efficiently in the normal and reverse phase, both for analytical and preparative purposes. In addition new polymeric CSPs have been prepared by using the same selector, suitably modified, as monomer. The new chiral stationary phases have been characterised by physicochemical methods and used for the resolution of various racemic compounds classes such as α-aryloxyacetic acids, alcohols, sulfoxides, selenoxides, phosphinates, tertiaryphosphine oxides, benzodiazepines etc. without prederivatization or as amines, amino acids, amino alcohols, nonsteroidal antiinflammatory agents in a derivatized form. The separated solutes structural variety suggests that multiple interaction sites are involved in the recognition process: some thermodynamic data relative to the CSPs - selectands interactions are also illustrated. © 1992 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040709
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Use of cellulose-based stationary phases for chiral separation in open tubular column chromatography (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 459-461 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective stationary phases ; mixed stationary phases ; open tubular columns ; GC ; SFC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Application of cellulose-based chiral stationary phases was extended to open tubular columns. These chiral materials were mixed with achiral matrix stationary phases. Compromises were found among the polarity and the ratio of achiral matrix polymers against the content of the chiral cellulose derivative in order to optimize the resolution of the investigated racemates. In GC, the high efficiency feature of open tubular columns allows fast analysis, however, compounds which express strong H-bond interaction with cellulose derivatives elute with a bad peak shape. The application of these stationary phases for open tubular SFC was more successful, because the solvation power of the mobile phase can compensate the strong interaction between the solute and the cellulose derivative. Immobilization of the stationary phases were achieved for SFC purposes. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040710
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    An improved synthesis of the enantiomers of bm-5 and their effects on the central in vivo release of acetylcholine (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 367-376 
    Details
    ISSN: 0899-0042
    Keywords: muscarinic agents ; in vivo brain dialysis ; stereoselectivity ; chemoselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide (BM-5), a putative postsynaptic agonist and presynaptic antagonist at muscarinic receptors, was resolved into the enantiomers by a new method suitable for large scale preparation. The method involves a chemoselective N-debenzylation as the key step. The enantiomers of BM-5 were obtained after six separate steps in 25% overall yield. The ability of the enantiomers to release acetylcholine was evaluated in vivo by use of brain dialysis. (R)-BM-5 was the more potent enantiomer in this assay. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040607
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    The influence of solute structure, temperature, and eluent composition on the chiral separation of 21 aminotetralins on a cellulose tris-3,5-dimethylcarbamate stationary phase in high-performance liquid chromatography (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 389-394 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; CHIRALCEL OD ; temperature effect ; enantiomeric separation ; aminotetralins ; dopamine agonists ; resolution ; chiral recognition mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present study 21 different chiral aminotetralins were used to investigate the mechanism behind their enantiomeric resolution (Rs) on a commercially available high-performance liquid chromatography (HPLC) cellulose tris-3,5-dimethylcarbamate stationary phase. The differences in the chemical structures of the aminotetralins used were never directly located on the chiral carbon. Their chromatographic behavior was studied for two eluent compositions at six different temperatures. Hydrogen bonding and π—π interactions are two possible solute-chiral stationary phase (CSP) interactions. Differences between the enantiomers in their spatial arrangement of positions involved in solute-CSP interactions were the major forces behind enantiomeric separation.Lowering the temperature increased the Rs for the aminotetralins having π-electrons not directly bonded to that part of the molecule where the hydrogen bonding with the CSP is located. Primary amines and secondary amines, with a sufficiently short N-alkyl substituent, showed a decrease of Rs with lower temperatures, all other aminotetralins yielding an increase of Rs with lower temperatures. © 1992 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Application of γ-cyclodextrin to enantiomeric purity determination of a new 2-amino-tetralin derivative by 1H-NMR spectroscopy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 404-405 
    Details
    ISSN: 0899-0042
    Keywords: NMR shift reagent ; 2-amino tetralin ; cyclodextrin ; enantiomeric excess ; optical purity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: γ-Cyclodextrin was used to perform chiral discrimination of (±)-5,6-diisobutyroyl-2-methylaminotetralin hydrochloride by 1H-NMR; the 95% enantiomeric excess of the (-)-isomer was determined successfully. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Stoichiometry of interaction between soluble ( - )-dopa melanin and enantiomers of ephedrine by NMR spectroscopy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 423-426 
    Details
    ISSN: 0899-0042
    Keywords: dissociation constants ; stereoselectivity ; synthetic melanin ; ephedrine alkaloid ; quantification ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic soluble ( - )-dopa melanin was prepared in deuteriated buffer, pH 8, by autooxidation of the precursor. At 6 mM of the precursor, the incorporation was over 90%. The changes in the line width measurements of N-CH3 protons of enantiomers of ephedrine in the soluble melanin were quantified by NMR spectroscopy. The dissociation constants of ( - )-1R,2S-ephedrine, (+)-1S,2R-ephedrine, ( - )-1R,2R-ψ-ephedrine, and (+)-1S,2S-ψ-ephedrine were 11.7, 4.20, 3.60, and 4.80 mM, respectively. Since the concentration of ( - )-dopa was known and since the conversion of ( - )-dopa to indole units of melanin was considered as 1:1, the stoichiometry of the interaction between the drug and the indole unit was calculated. Based on the dissociation constants of the enantiomers, it appears that up to four molecules of ( - )-ephedrine can interact with one indole unit of the melanin, while such a ratio for other isomers appear to be 2:1. The preference by indole units of melanin is stereoselective. © 1992 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Synthetic D- and L-enantiomers of 2,2-difluoro-2-deoxy-myo-inositol 1,4,5-trisphosphate interact differently with myo-inositol 1,4,5-trisphosphate binding proteins: Identification of a potent small molecule 3-kinase inhibitorPreliminary communication: Sawyer, D.A., Potter, B.V.L. Total Synthesis of L-2,2-difluoro-2-deoxy-myo-inositol 1,4,5-trisphosphate, a potent inhibitor of the enzymes of D-myo-inositol 1,4,5-trisphosphate metabolism. Bioorg. Med. Chem. Lett. 1:705 - 710, 1991. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 415-422 
    Details
    ISSN: 0899-0042
    Keywords: inositol phosphates ; fluoro-analogues ; Ca2+ mobilization ; enzyme inhibition ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of two enantiomeric fluoro-analogues of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] to mobilize intracellular Ca2+ stores in SH-SY5Y neuroblastoma cells has been investigated. ( - )-D-2,2-difluoro-2-deoxy-myo-Ins(1,4,5)P3 [D-2,2-F2-Ins(1,4,5)P3] was a full agonist [EC50 0.21 μM] and slightly less potent than D-Ins(1,4,5)P3 [EC50 0.13 μM]. (+)-L-2,2-F2Ins(1,4,5)P3 was a very poor agonist, confirming the stereospecificity of the Ins(1,4,5)P3 receptor. D-2,2-F2-Ins(1,4,5)P3 mobilized Ca2+ with broadly similar kinetics to Ins(1,4,5)P3 and was a substrate for Ins(1,4,5)P3 3-kinase inhibiting Ins(1,4,5)P3 phosphorylation (apparent Ki = 10.2 μM) but was recognised less well than Ins(1,4,5)P3. L-2,2-F2-Ins(1,4,5)P3 was a potent competitive inhibitor of 3-kinase (Ki = 11.9 μM). Whereas D-2,2-F2-Ins(1,4,5)P3 was a good substrate for Ins(1,4,5)P3 5-phosphatase, L-2,2-F2Ins(1,4,5)P3 was a relatively potent inhibitor (Ki = 19.0 μM). © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040703
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    An unexpected temperature effect obtained on enantiomer separation using CBH i-silica as a chiral stationary phase: Increase in retention and enantioselectivity at elevated column temperature: A chromatographic and microcalorimetric study (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 505-508 
    Details
    ISSN: 0899-0042
    Keywords: cellulase ; CBH I-silica ; temperature dependent enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040808
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Direct coupled column separation and determination of the diastereomeric glucuronides of almokalant, a new class III antiarrhythmic drug, in human urine (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 509-514 
    Details
    ISSN: 0899-0042
    Keywords: bioanalysis ; almokalant glucuronides ; diastereomers ; metal complexes ; porous graphitic carbon ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A reversed-phase coupled column separation (CCS) system for the analysis of two diastereomeric glucuronides of almokalant, a new class III antiarrhythmic drug, in human urine is described. After direct injection of urine samples (50 μl) the glucuronides were isolated by complex formation on a terbium(III) loaded strong cation exchanger at alkaline pH. The solutes were eluted from the precolumn by an acidic mobile phase, enriched and separated on Hypercarb (porous graphitic carbon) as analytical column with 0.1 M acetic acid pH 2.8 and 30% acetonitrile as mobile phase. The calibration graph was linear (r2 = 0.9999) and the detection limits were in the low picomole (UV) or femtomole (fluorescence) range. Optimization of the analytical column revealed that elution order and selectivity for the glucuronides were dependent on the buffer agent and temperature used. By appropriate choice of mobile phase conditions all four diastereomers could be separated. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040809
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Indirect chiral separation and analyses in human biological fluids of the stereoisomers of a thienothiopyran-2-sulfonamide (TRUSOPT), a novel carbonic anhydrase inhibitor with two chiral centers in the molecule (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 515-519 
    Details
    ISSN: 0899-0042
    Keywords: chiral drugs ; urea derivatives ; topical CAI inhibitors ; chiral inversion in humans ; MK-507 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The indirect chiral separation of the four stereoisomers (1)--(4) of a novel carbonic anhydrase inhibitor with two chiral centers in the molecule is reported. The method is based on chemical derivatization of the secondary amino group of the inhibitor with chiral isocyanate, formation of diastereomeric urea derivatives, each with three chiral centers in the molecule, and their separation under nonchiral HPLC conditions. The attempts to separate racemic mixture (1)+(2) from its diastereomeric counterpart (3)+(4) under nonchiral conditions, and to separate enantiomers (1) and (2) directly on a chiral stationary phase (CSP) are also reported. The indirect method was utilized for the assessment of an in vivo inversion of configuration at either one or both chiral centers of the molecule of (1). Analyses of selected whole blood and urine samples from human subjects after multiple bilateral topical ocular dosing with (1) did not reveal the presence of any of the three possible stereoisomers (2)--(4) of (1) indicating that the inversion of configuration at neither one nor two chiral centers of (1) occurs in vivo. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040810
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    O-versus S-protonation in diaryl sulfoxides: A semi-empirical mo investigation: Comparison with solution studies in superacids (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 244-252 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The protonation of diphenyl sulfoxide and several substituted diphenyl sulfoxides was probed by the MNDO-PM3 method to gain a theoretical insight into the experimentally observed preference for stable diphenyl sulfoxonium ion formation (O-protonation) in 1:1 FSO3H - SbF5 (Magic Acid) - SO2. In agreement with solution studies, O- protonation is uniformly favored (by ca 17 kcal mol -1) over S-protonation. The differences in the heats of formation of protonated and unprotonated diphenyl sulfoxides are increased by electron-withdrawing substituents (F, CF3) and decreased by electron-donating groups (Me, OMe). Variations in the SO bond length and bond order in the onium ions are compatible with simple resonance arguments and the oxonium/sulfonium character of both the O- and S-protonated onium ions. Surprisingly, the O- and S-protonated dibenzothiophene S-oxides are predicted to have identical energetics as compared with the corresponding protonated diphenyl sulfoxides. On structure optimization dibenzothiophene S-oxide itself, if the initial geometry is somewhat twisted, rearranges by ring expansion to give a new heterocycle with lower energy. A rotational barrier study on the parent O-protonated diphenyl sulfoxide showed two minima, separated by 1.3 kcal mol-1, at HOSC dihedral angles of 60° and 240°. The two conformations correspond to syn and anti orientations of the OH proton relative to the aromatic rings, and support the lowtemperature solution observations of the presence of two distinct sulfoxonium ions in solution. The rotational barriers for diphenyl sulfoxonium cation are compared with those of O-protonated dimethyl sulfoxide.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050505
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...