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  • Organic Chemistry  (891)
  • Inorganic Chemistry  (693)
  • 1995-1999
  • 1990-1994  (1,584)
  • 1950-1954
  • 1990  (1,584)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1990-1994  (1,584)
  • 1950-1954
Year
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and evaluation of two novel “mixed” chiral stationary phases deriving from tyrosine: Csps designed for the resolution of either π-acid or π-basic racemates (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 106-119 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separations ; chiral stationary phases ; tyrosine chiral selector ; γ-mercaptopropyl silica gel ; HPLC, chiral recognition mechanisms ; mobile phase optimization ; UV-vis charge transfer band ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and chromatographic evaluation of two novel chiral stationary phases (CSPs) deriving from (S)-tyrosine are reported. The chiral graft has been designed in order to bear both π-acid and π-basic sites, each one being connected to a distinct asymmetric centre. An intramolecular π-π interaction may take place within these CSPs, leading to an energetically favoured conformation of the chiral selector (CS). The enantiorecognition ability of these CSPs was investigated for various classes of either π-acid or π-basic racemates. It is shown that these CSPs are able to separate simultaneously π-acid and π-basic racemates. Finally, chiral recognition mechanisms and mobile phase optimization are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020208
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  • 2
    Electronic Resource
    Electronic Resource
    Chemical synthesis, absolute configuration, and stereochemistry of formation of 10-hydroxywarfarin: A major oxidative metabolite of (+)-(r)-warfarin from hepatic microsomal preparations (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 96-105 
    Details
    ISSN: 0899-0042
    Keywords: human liver ; P-450IIIA family ; 10-hydroxywarfarin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a diastereomerically pure 10-hydroxywarfarin [4-hydroxy-3-(2-hydroxy-3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one] was accomplished in three steps from racemic warfarin. The relative configuration of the synthetic product was established by conversion to a cyclic derivative followed by NMR and X-ray diffraction analysis. Absolute stereochemistry was determined by enzymatic conversion of either of the pure enantiomers of warfarin to a 10-hydroxy metabolite of known relative configuration. Metabolic formation of 10-hydroxywarfarin was studied using hepatic microsomal preparations from female rats and man. The formation of 10-hydroxywarfarin catalyzed by hepatic microsomes from both dexamethasone-treated rats and man was highly stereoselective [(R)/(S): 3.4-9.0] for (R)-warfarin. In contrast, little stereoselectivity was observed in reactions catalyzed by untreated rat liver microsomes. The resultant stereochemistry at the site of oxidation was also found to be highly dependent on substrate stereochemistry. (R)-Warfarin gave (9R;10S)-10-hydroxywarfarin with only a trace of the (9R;10R) isomer irrespective of which enzyme preparation was used for catalysis, while (S)-warfarin gave (9S;10R)-10-hydroxywarfarin with only a trace of the (9S;10S) isomer, again irrespective of which enzyme preparation was used for catalysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020207
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  • 3
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 128-128 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020211
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  • 4
    Electronic Resource
    Electronic Resource
    Racemates versus enantiomers in drug development: Dogmatism or pragmatism? (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 129-133 
    Details
    ISSN: 0899-0042
    Keywords: chiral drugs ; racemates ; eutomers ; distomers ; pharmacodynamic enantioselectivity ; pharmacokinetic enantioselectivity ; enantioselective interactions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020302
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  • 5
    Electronic Resource
    Electronic Resource
    Stereoselective disposition of ibuprofen and flurbiprofen in rats (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 134-140 
    Details
    ISSN: 0899-0042
    Keywords: pharmacokinetics ; enantiomers ; 2-arylpropionates ; chiral inversion ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R)-2-Arylpropionates are often inverted to the pharmacologically active S-enantiomers in vivo, although there is significant interspecies variability in inversion. In order to provide a basis for determining the biochemical consequences of this unique process using rats as a model, it was important to establish the pharmacokinetic disposition of the enantiomers of ibuprofen, a drug well inverted in man and flurbiprofen, a drug apparently poorly inverted in man. Rats were dosed i.v. with a single dose of (R)-or (S)-ibuprofen (20 mg/kg), (R,S)-ibuprofen (40 mg/kg), (R)- or (S)-flurbiprofen (10 mg/kg), or (R,S)-flurbiprofen (20 mg/kg). Each treatment group consisted of six animals. Serial blood samples were withdrawn over a period of 6 h for ibuprofen and 10 h for flurbiprofen. These drugs were assayed in plasma by a stereospecific HPLC assay. The pharmacokinetics of the ibuprofen and flurbiprofen enantiomers were evaluated using a two-compartment open model with conversion of the R- to S-enantiomers in the central compartment. There was 50 ± 4% inversion of (R)-ibuprofen, a figure similar to that observed in man and (R)-ibuprofen had a higher clearance (12.6 ± 1.3 ml/min/kg) than (S)-ibuprofen (7.7 ± 0.7 ml/min/kg; P 〈 0.01). The clearance of (R)- flurbiprofen after racemate (2.3 ± 0.1 ml/min/kg) was higher than its clearance when administered alone (1.7 ± 0.2 ml/min/kg; P 〈 0.01), indicating a pharmacokinetic interaction between the enantiomers (most probably at plasma protein binding sites). A corresponding difference was not observed for ibuprofen. There was a small amount of inversion of (R)-flurbiprofen as determined by area analysis (4.5 ± 1.6%). However, this calculation may be in some error because of the interaction between the enantiomers. These data demonstrate quantitative similarities in the inversion of ibuprofen and flurbiprofen in rats and man, a useful basis for comparing the effects of these two drugs on fatty acid metabolism.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020303
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  • 6
    Electronic Resource
    Electronic Resource
    Stereochemical features of 1,4-benzodiazepin-2-ones bound to human serum albumin: Difference CD and UV studies (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 167-174 
    Details
    ISSN: 0899-0042
    Keywords: benzodiazepines ; circular dichroism ; difference spectroscopy ; human serum albumin ; stereospecific interaction ; chiral discrimination ; electronic absorption spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemistry of an achiral (Diazepam) and two chiral (3-methyl and 3-succinyloxy substituted) 1,4-benzodiazepin-2-ones interacting with human serum albumin (HSA) has been investigated by making use of difference absorption (UV) and circular dichroism (CD) spectroscopies. Evidence is obtained for a higher affinity with HSA for one of the two possible conformations of the seven-membered benzodiazepine ring. The red shift revealed by the absorption difference spectrum between the free and the bound drug accounts for the CD difference spectra observed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020308
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  • 7
    Electronic Resource
    Electronic Resource
    Interindividual variability in the enantiomeric disposition of ibuprofen following the oral administration of the racemic drug to healthy volunteers (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 249-256 
    Details
    ISSN: 0899-0042
    Keywords: ibuprofen enantiomers ; R,S-ibuprofen ; enantiomer disposition ; pharmacokinetics ; human study ; interindividual variability ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The plasma disposition of the enantiomers of ibuprofen has been investigated following the oral administration of the racemic drug (400 mg) to 24 healthy male volunteers. The plasma elimination of (R)-ibuprofen was found to be more rapid than that of the S-enantiomer [plasma half-life: (R) 2.03 h; (S) 3.05 h; 2P 〈 0.001], resulting in a progressive enrichment in the plasma content of this isomer, some 64% of the total area under the plasma concentration time curves (AUC) being due to the pharmacologically active enantiomer. The influence of dose on the pharmacokinetic characteristics of the enantiomers of ibuprofen, over the range 200-800 mg, was investigated in three subjects. Examination of dosenormalized AUC values and oral clearance indicate the dose dependence of (R)-ibuprofen disposition.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020410
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  • 8
    Electronic Resource
    Electronic Resource
    Enantioselective binding of mephobarbital to plasma proteins (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 257-262 
    Details
    ISSN: 0899-0042
    Keywords: barbiturates ; stereoisomers ; protein binding ; albumin ; age dependence ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective protein binding of mephobarbital (MPB) was investigated in human plasma and human serum albumin solutions by equilibrium dialysis. A small but statistically significant difference was observed in the in vitro plasma protein binding of the enantiomers; (S)-MPB was ∼59% bound and (R)-MPB ∼67% bound. The binding to albumin [(S)-MPB: ∼29% bound, and (R)-MPB: ∼41% bound] was less than to plasma proteins but showed somewhat greater enantioselectivity, suggesting that albumin binding is a major source of the enantioselectivity in plasma. The effects of MPB concentration, of varying enantiomeric concentration ratio, and of phenobarbital on the enantioselective binding of MPB were studied. The effect of age was also investigated by measuring the binding in plasma from 8 young (18-25 yr) and 8 elderly (〉60 yr) male subjects who took single doses of MPB. The results were in close agreement with the in vitro binding data, and the binding of both enantiomers was marginally but significantly lower in the young compared with the elderly subjects. These differences in binding were consistent with previously observed pharmacokinetic differences between the two subject groups.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020411
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  • 9
    Electronic Resource
    Electronic Resource
    Immobilized serum albumin: Rapid HPLC probe of stereoselective protein-binding interactions (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 263-268 
    Details
    ISSN: 0899-0042
    Keywords: protein binding ; stereoselectivity ; immobilized human serum albumin ; HPLC chiral stationary phase ; chiral drugs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A human serum albumin-based HPLC chiral stationary phase (HSA-CSP) has been examined as a tool to investigate binding of chiral drugs to HSA and drug-drug protein-binding interactions. Rac-oxazepam hemisuccinate (OXH) was used as a model compound and the chromatographic retention (k′) of its enantiomers was determined after addition of displacers to the mobile phase. Compounds known to bind at the same site as OXH and at different sites were tested for their displacing capacities. Competitive binding interactions between the OXH enantiomers and displacers in the mobile phase were reflected by decreases in the k′s of (R)- and (S)-OXH. The results indicate that retention on the HSA-CSP accurately reflects binding to native HSA and the technique can determine enantioselective and competitive binding interactions at specific sites on HSA. The HSA-CSP was also able to recognize separate binding areas for (S)- and (R)-OXH.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020412
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  • 10
    Electronic Resource
    Electronic Resource
    An HPLC procedure for the enantiomeric purity of an optically active cytosine analogue using ligand exchange (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 275-279 
    Details
    ISSN: 0899-0042
    Keywords: nucleotide analogue ; antiviral ; chiral separation ; complexation ; ion-pairing ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An acylonucleotide analogue, 1-[3-hydroxy-2-(phosphonyl-methoxy)propyl]cytosine (HPMPC), has shown activity against herpes simplex Type I and Type II viruses. An HPLC separation of the R- and S-enantiomers of HPMPC by ligand exchange using a mobile phase containing phenylalanine as the chiral modifier and copper(II) as the metal ion is reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020414
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  • 11
    Electronic Resource
    Electronic Resource
    High-Performance liquid chromatographic resolution of oxamniquine enantiomers: Application to in vitro metabolism studies (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 269-274 
    Details
    ISSN: 0899-0042
    Keywords: α1-acid glycoprotein ; chiral-AGP ; in vitro studies ; chiral optimisation ; cytosolic enzymes ; oxamniquine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the HPLC analysis of oxamniquine enantiomers in liver fraction incubates, using a second-generation α1-acid glycoprotein-based column (Chiral-AGP). Oxamniquine is extracted from the incubation media by liquid-liquid extraction, using diethyl ether. The dried residue is redissolved in eluent, filtered, then injected directly onto the analytical column. The extraction method affords recoveries of oxamniquine of approximately 93%, at concentrations up to 525 μg/ml, with an average relative standard deviation of 5.9%. The limit of detection of the method (to give an SNR = 2 at 246 nm) is 0.3 ng on-column for the first eluting, laevorotatory enantiomer and 2.3 ng for the dextrorotatory isomer. The method allowed study of the depletion of oxamniquine enantiomers in liver postimicrosomal incubates. In the rat, a turnover of 21.9% was observed, with no apparent enantioselectivity. Similar observations were made for a mouse liver subcellular fraction incubation. The absence of enantioselectivity in this biotransformation may be attributable to the low substrate specificity of the oxidase or dehydrogenase enzymes involved.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020413
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  • 12
    Electronic Resource
    Electronic Resource
    Optical resolution and absolute configuration of a nonsteroidal antiinflammatory drug, 2-(10,11-Dihydro-10-oxodibenzo-[b,f]thiepin-2-yl)propionic acid (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 280-283 
    Details
    ISSN: 0899-0042
    Keywords: antiinflammatory drug ; 2-arylpropionic acid derivative ; CN-100 ; enantiomer ; resolution ; racemization ; absolute configuration ; chiral column ; direct separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound (±)-1 (CN-100) was efficiently resolved into a pair of enantiomers by fractional crystallization of the diastereomeric salts of (-)-and (+)-1-phenylethylamine. The purity of the enantiomers was determined using the chiral cellulose column (CHIRALCEL OJ®) which allowed direct separation of the enantiomers. A separation factor (α) of 1.73 was obtained. X-Ray crystallographic analysis of the (+)-isomer [salt of (-)-1-(4-bromophenyl)ethylamine] showed that this enantiomer has S-configuration. Biological studies have shown that only the (+)-isomer has antiinflammatory activity. Racemization of (-)-isomer was carried out by heating its propionic acid solution in the presence of mineral acid, such as HBr.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020415
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  • 13
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 288-288 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020416
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  • 14
    Electronic Resource
    Electronic Resource
    Stereoselective inhibition of thromboxane-induced coronary vasoconstriction by 1,4-dihydropyridine calcium channel antagonists (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 233-240 
    Details
    ISSN: 0899-0042
    Keywords: 1,4-dihydropypyridine enantiomers ; stereoselectivity ; thromboxane A2 (TxA2) ; coronary vasoconstriction ; calcium channel binding ; blood pressure ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The biological activity of the (+)-S- and (-)-R-enantiomers of niguldipine, of the (-)-S- and (+)-R-enantiomers of felodipine and nitrendipine, and of rac-nisoldipine and rac-nimodipine was investigated in vitro and in vivo. Inhibition of coronary vasoconstriction due to the thromboxane A2 (TxA2)-mimetic U-46619 in guinea pig Langendorff hearts, displacement of (+)-[3H]isradipine from calcium channel binding sites of guinea pig skeletal muscle T-tubule membranes, and blood pressure reduction in spontaneously hypertensive rats were determined. The enantiomers were obtained by stereoselective synthesis. Cross-contamination was 〈0.5% for both S- and R-enantiomers of niguldipine and nitrendipine and 〈1% for those of felodipine. From the doses necessary for a 50% inhibition of coronary vasoconstriction, stereoselectivity ratios for (+)-(S)-/(-)-(R)-niguldipine, (-)-(S)-/(+)-(R)-felodipine, and (-)-(S)-/(+)-(R)-nitrendipine of 28, 13, and 7, respectively, were calculated. The potency ratio racnisoldipine/rac-nimodipine was 3.5. Ratios obtained from binding experiments and antihypertensive activity were (+)-(S)-/(-)-(R)-niguldipine = 45 and 35, (-)-(S)-/(+)-(R)-felodipine = 12 and 13, (-)-(S)-/(+)-(R)-nitrendipine = 8 and 8, and rac-nisoldipine/rac-nimodipine = 8 and 7, respectively. Highly significant correlations were found between the in vitro potency of the substances to prevent U-46619-induced coronary vasoconstriction and their affinity for calcium channel binding sites as well as their antihypertensive activity. The mechanism of TxA2-induced coronary vasoconstriction in guinea pig Langendorff hearts can be readily explained by a transmembrane influx of extracellular Ca2+ susceptible to stereoselective blockade by 1,4-dihydropyridine calcium channel antagonists.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020408
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  • 15
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020101
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  • 16
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    Metabolism of halazepam by rat liver microsomes: Stereoselective formation and n-dealkylation of 3-hydroxyhalazepam (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 1-9 
    Details
    ISSN: 0899-0042
    Keywords: halazepam ; 3-hydroxyhalazepam ; diazepam ; N-desmethyldiazepam ; oxazepam ; enantiomers ; rat liver microsomes ; stereoselectivity ; enantioselectivity ; hydroxylation ; enantioselective N-dealkylation ; kinetics of racemization ; circular dichroism spectra ; chiral stationary phase ; high-performance liquid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolism of halazepam [7-chloro-1,3-dihydro-5-phenyl-1-(2,2,2-trifluoroethyl)-2H-1,4-benzodi epin-2-one, HZ] was studied by incubation with liver microsomes prepared from untreated, phenobarbital (PB)-treated, and 3-methylcholanthrene (3MC)-treated male Sprague-Dawley rats. Metabolites of HZ were separated by normal-phase HPLC. Relative rates of HZ metabolism by liver microsomes prepared from untreated and treated rats were PB-treated ≫ untreated 〉 3MC-treated at low concentration of microsomal enzymes (0.25 mg protein per ml of incubation mixture) and PB-treated ≫ 3MC-treated ≈ untreated at high concentration of microsomal enzymes (2 mg protein per ml of incubation mixture). The relative amounts of major metabolites were found to be 3-hydroxy-HZ (3-OH-HZ) 〉 N-desalkylhalazepam (NDZ, also known as N-desmethyldiazepam and nordiazepam) ≫ oxazepam (OX) for all three rat liver microsomal preparations and the distribution of metabolites was independent of microsomal enzyme concentrations. Enantiomers of 3-OH-HZ were resolved by HPLC on a Chiralcel OC column (cellulose trisphenylcarbamate coated on silica gel, particle size 10 μm). 3-OH-HZ enantiomeres have racemization half-lives of ∼ 150 min in pH 4,7.5, and 10 aqueous solutions. 3-OH-HZ formed in the metabolism of HZ by liver microsomes prepared from untreated and treated rats were found to have 3R/3S enantiomer rations of 37/63 (untreated), 55/45 (PB-treated), and 36/64 (3MC-treated), respectively. N-dealkylation of 3-OH-HZ by liver microsomes from PB-treated rats was substrate enantioselective; the 3R-enantiomer was N-dealkylated faster than 3S-enantiomer. The results indicated that the stereoselective C3-hydroxylation of HZ is dependent on the cytochromes P-450 present in the rat liver microsomal preparations; pro-R in liver microsomes from PB-treated rats and pro-S in liver microsomes from untreated and 3MC-treated rats, respectively.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530020102
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  • 17
    Electronic Resource
    Electronic Resource
    Preparative resolutions of an α-methyl carboxylic acid through selective transformations of readily epimerizable intermediates (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 52-57 
    Details
    ISSN: 0899-0042
    Keywords: diastereomeric amide ; chiral synthon ; oxazolidone ; lithium hydroxide ; cesium carbonate ; ethylaluminum dichloride ; Friedel-Crafts ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two preparations of the enantiomers of 2 are described. The first makes use of the chromatographic separation of the diastereomeric amides 6a and 6b. Standard hydrolysis of these amides caused racemization, so a milder sequence was developed which utilized carbonyldiimidazole and 1 equivalent of 1 N LiOH. The second preparation involved classical resolution of 9 with (-)-cinchonidine. Subsequent transformations of this substrate involved ester formation, Friedel-Crafts acylation, and ester hydrolysis, all without racemization. The most notable of these reactions was the use of EtAlCl2 in the Friedel-Crafts step, which provided a mild acylation of 10. This second preparation affords a high yield, mild process for the potential preparation of kilogram quantities of (-)-(R)-2b.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020108
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  • 18
    Electronic Resource
    Electronic Resource
    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 65-66 
    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.530020110
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  • 19
    Electronic Resource
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    Eudismic analysis of a series of muscarinic ligands carrying a 1,3-oxathiolane nucleus (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 79-84 
    Details
    ISSN: 0899-0042
    Keywords: eudismic analysis ; muscarinic ligands ; muscarinic receptors sub-groups ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eudismic analysis was performed on a set of 14 muscarinic ligands carrying a 1,3-oxathiolane nucleus, in order to obtain information about both the existence of receptor subgroups and of agonist and competitive antagonist interaction sites. The results obtained were compared with those from a study of the enantioselectivity of the pairs of enantiomers. The two approaches do not appear to be completely equivalent and would seem to complement each other usefully.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530020204
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  • 20
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    (R)- and (S)-5-hydroxy-2-(dipropylamino)tetralin (5-OH DPAT): Assessment of optical purities and dopaminergic activities (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 90-95 
    Details
    ISSN: 0899-0042
    Keywords: stereoselectivity ; 5-OH DPAT ; dopamine D2-receptor antagonist ; chiral ion pair chromatography ; N-benzyloxycarbonylglycyl-L-proline (L-ZGP) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic 5-hydroxy-2-(dipropylamino)tetralin (5-OH DPAT), a potent and selective dopamine (DA) D2-receptor agonist, was resolved into the enantiomers by a new method. The enantiomers of 5-OH DPAT were determined by chiral ion-pair chromatography using N-benzyloxycarbonylglycyl-L-proline as the counter ion. The enantiomeric purity of (R)-5-OH DPAT was found to be 〉 99.7%. The ability of the enantiomers to change the rat brain DOPA levels was evaluated in vivo. The results indicate that (R)-5-OH DPAT is a weakly potent DA D2-receptor antagonist.
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    Reversal of elution order of urea and thiourea derivatives of propranolol enantiomers on ionically versus covalently bound pirkle phases (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 120-123 
    Details
    ISSN: 0899-0042
    Keywords: Pirkle phases ; propranolol enantiomers ; urea derivatives ; thiourea derivatives ; chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chromatographic performance of a series of urea and thiourea derivatives of (±)-propranolol has been evaluated on three different Pirkle stationary phases. Seven different isocyanate reagents were used to generate a range of both aliphatic and aromatic urea derivatives with the isothiocyanates yielding the corresponding thiourea analogues. The Pirkle phases employed consisted of 3,5-dinitrobenzoylphenylglycine and 3,5-dinitrobenzoylleucine, both ionically and covalently bound to aminopropyl silica as well as phenethylpropylurea (covalently attached only). The urea derivatives were consistently more strongly retained on covalently bound columns than their thiourea counterparts. This is in contrast to the situation observed for the ionic columns, where the thiourea derivatives were the more strongly retained on the phenylglycine column and the more strongly retained in four of seven instances on the leucine column. The underlying mechanisms giving rise to these differences in retention are as yet unidentified but appear to involve the urea group.
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    URL: http://dx.doi.org/10.1002/chir.530020209
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020301
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    Enantioselective aliphatic hydroxylations of racemic 1-hydroxy-3-methylcholanthrene by rat liver microsomes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 141-149 
    Details
    ISSN: 0899-0042
    Keywords: 3-methylcholanthrene ; 1-hydroxy-3-methylcholanthrene ; 1-hydroxy-3-hydroxymethylcholanthrene ; 3-methylcholanthrene trans-1,2-diol ; 3-methylcholanthrene cis-1,2-diol ; high-performance liquid chromatography ; chiral stationary phase ; resolution of enantiomers ; absolute configuration ; circular dichroism spectra ; enantioselective hydroxylation ; rat liver microsomes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomeric pairs of 1-hydroxy-3-hydroxymethylcholanthrene (1-OH-3-OHMC), 3-methylcholanthrene (3MC) trans- and cis-1,2-diols, and 1-hydroxy-3-methylcholanthrene (1-OH-3MC) were resolved by HPLC using a covalently bonded (R)-N-(3,5-dinitrobenzoyl)phenylglycine chiral stationary phase (Pirkle type 1A) column. The absolute configuration of an enantiomeric 3MC trans-1,2-diol was established by the exciton chirality CD method following conversion to a bis-p-N,N-dimethylaminobenzoate. Incubation of an enantiomeric 1-OH-3MC with rat liver microsomes resulted in the formation of enantiomeric 3MC trans- and cis-1,2-diols; the absolute configurations of the enantiomeric 1-OH-3MC and 3MC cis-1,2-diol were established on the basis of the absolute configuration of an enantiomeric 3MC trans-1,2-diol. Absolute configurations of enantiomeric 1-OH-3-OHMC were determined by comparing their CD spectra with those of enantiomeric 1-OH-3MC. The relative amount of three aliphatic hydroxylation products formed by rat liver microsomal metabolism of racemic 1-OH-3MC was 1-OH-3-OHMC 〉 3MC cis-1,2-diol 〉 3MC trans-1,2-diol. Enzymatic hydroxylation at C2 of racemic 1-OH-3MC was enantioselective toward the 1S-enantiomer over the 1R-enantiomer (∼3/1); hydroxylation at the C3-methyl group was enantioselective toward the 1R-enantiomer over the 1S-enantiomer (∼58/42). Rat liver microsomal C2-hydroxylation of racemic 1-OH-3MC resulted in a 3MC trans-1,2-diol with a (1S,2S)/(1R,2R) ratio of 63/37 and a 3MC cis-1,2-diol with a (1S,2R)/(1R,2S) ratio of 12/88, respectively.
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    Stereoselective effect of warfarin and bilirubin on the binding of 5-(o-chlorophenyl)-1,3-dihydro-3-methyl-7-nitro-2H-1,4- benzodiazin-2-one enantiomers to human serum albumin (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 161-166 
    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 binding of the title benzodiazepine enantiomers and its modulation by warfarin and bilirubin were studied by chromatography on human serum albumin (HSA) immobilized on Sepharose 4B, and also by a combination of ultrafiltration and circular dichroism (UF-CD) methods. In the absence of warfarin and bilirubin the binding of the benzodiazepine was not stereoselective. (S)-Benzodiazepine and (S)-warfarin mutually increased the binding of each other, while the binding of (R)-benzodiazepine was preferentially enhanced on HSA saturated with bilirubin.
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    URL: http://dx.doi.org/10.1002/chir.530020307
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    Determination of the absolute configuration and enantiomeric purity of alcohols from the 13C-NMR spectra of the corresponding MTPA esters (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 175-184 
    Details
    ISSN: 0899-0042
    Keywords: cyclohexanols ; sterols ; Dale-Mosher model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From a study of the 13C-shift values of the MTPA esters of 3-substituted cyclohexanols of known absolute configuration an empirical rule has been developed to determine the absolute configuration of chiral cyclohexanols. The method is based on the Dale-Mosher model, which was originally developed for 1H-NMR spectra. The scope and limitations of this method are discussed. The enantiomeric purity of the alcohols can be determined simultaneously by integration of the signals in well-resolved diastereotopic carbon pairs.
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    Enantiomeric resolution of DNS-amino acids by ligand exchange chromatography: Comparison of different chiral amino acid amides as additives to the mobile phase (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 190-193 
    Details
    ISSN: 0899-0042
    Keywords: HPLC ; bis(L-amino acid amidato)-copper(II) complexes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study developing enantiomeric separations by metal chelate additives to the mobile phase in reversed-phase liquid chromatography is reported. In particular the use of Cu(II) complexes of L-prolinamide (L-ProNH2) and L-valinamide (L-ValNH2) is examined and discussed. Interestingly, for a series of DNS-amino acids these selectors show higher enantioselectivity than that obtained with the corresponding nonderivatized amino acid-Cu(II) complexes.
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    Enantiomeric resolution of DNS-amino acids by ligand exchange chromatography using l-phenylalaninamide together with Cu(II) ions as chiral additives to the eluent (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 194-199 
    Details
    ISSN: 0899-0042
    Keywords: chiral recognition ; copper(II) complexes ; high-performance liquid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resolution of various α-DNS DL-amino acids by ligand exchange chromatography of L-phenylalaninamide-copper(II) complexes on a conventional reversed-phase packing is reported. Parameters of the mobile phase which control retention and enantioselectivity such as concentration of Cu(II) ion and L phenylalaninamide (PheNH2), pH, ionic strength, and acetonitrile content were examined. In order to obtain further information on the distribution and stability of the prevailing complex species formed between the metal ion and the chiral selector, spectrophotometric measurements in different media were also carried out.
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020401
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    A vivid model illustrating chiral recognition induced by achiral structures (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 208-210 
    Details
    ISSN: 0899-0042
    Keywords: enantioselectivity ; three-point model ; didactic model ; chiral separations ; ligand-exchange chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If diastereomeric complexes are adsorbed on a surface or if they include a molecule of solvent, two points of attractive interaction between the chiral species of the complex can be sufficient for mutual chiral recognition of these species. In special cases even one single point of interaction is sufficient. This extension of the three-point contact rule of Dalgliesh, first observed in chiral ligand-exchange chromatogrphy, can be demonstrated by using hands.
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    Studies on the stereoselective effects of a novel 5-HT2 receptor antagonist on contractile responses of rat aorta (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 226-228 
    Details
    ISSN: 0899-0042
    Keywords: optical isomers ; enantiomers ; vascular smooth muscle ; 5-hydroxytryptamine ; noradrenaline ; potassium ; calcium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of the enantiomers of a novel 5-HT2 receptor antagonist, (±)-(1R,3S)-1-[2-[4-[3-(p-fluorophenyl)-1-indanyl]-piperazinyl]ethyl]-2-imidazolidinone, was studied on serotonin (5-HT), noradrenaline (NA), potassium (K+), and calcium (Ca2+)-induced contractions in isolated rat thoracic aorta. The enantiomers shifted the 5-HT, NA, K+, and Ca2+ concentration-response curves to the right in a concentration-dependent manner and depressed the maximal contractile responses. The (+)-enantiomer was a far more potent inhibitor of 5-HT-induced contractions than the (-)-enantiomer. The (+)-enantiomer and phentolamine, both at 10-6 M, had equal inhibitory effects on NA-evoked contractions. The (+)-enantiomer was again more potent in inhibiting NA-induced contractions than the (-)-enantiomer. Both enantiomers had an equieffective inhibitory effect on K+ and Ca2+-induced contractions. The results show that the 5-HT and α-adrenoceptor antagonism of the two enantiomers is stereoselective, the (+)-enantiomer being more potent than the (-)-enantiomer. In contrast the enantiomers had equal, nonstereoselective inhibitory effects on K+ and Ca2+-evoked contractions.
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    URL: http://dx.doi.org/10.1002/chir.530020406
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    Quantitation of the criticality of chiral centers toward stereoselective recognition: Epimeric eudismic analysis of 1,3-oxathiolane muscarinic agonists and antagonists (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 211-218 
    Details
    ISSN: 0899-0042
    Keywords: stereoselectivity ; quantitative stereo-structure-activity relationships ; muscarinic receptor ; enantiomeric and epimeric ligands ; criticality of chiral centers ; substructure affinity contributions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently published data1 on the aftinities of 14 pairs of chiral ligands, (1,3-oxathiolanes) for muscarinic receptors in three different tissues were subjected to eudismic analysesThe enantiomeric eudismic-affinity correlations (EACs) found by Gualtieri et al.1 were confirmed and extended to the submolecular level: (1) regressions of the eudismic index (log affinity ratio; EI) against eutomer potency of the average affinities were highly significant, indicating that the binding sites in all three tissues are identical; (2) for the five agonists the EAC was shifted to lower affinities and had a small slope (EAQ), in agreement with previous observations in other systems; (3) of the nine antagonists, six gave an excellent regression with unit slope, practically superimposable on that previously obtained for 10 structurally different oxotremorine derivatives, while two others (1,3-oxathiolanes) could be plotted on a separate line with the same EAQ, but shifted to higher affinities; (4) the aberrant low EI of the last antagonist could be explained in terms of its structureFurthermore, an epimeric EAC (EEAC) revealed additional important information for quantitative stereo-structure-activity relationships (QSSAR): the 25 possible epimeric comparisons were found to group into 6 different EACs in accord with differences in their structure: (1) the agonists fell on three separate lines of nearly identical (unitary) slope, which grouped cleanly in terms of the center of epimerization (positions 2, 3, and 5); (2) the antagonists of lower affinity fell on three lines with a common X-intercept but with different slopes corresponding to epimerization at the different centers of chirality, indicating that these display quantitative differences in their criticality toward stereoselective recognition; (3) the remaining two antagonists of higher affinity fell on a separate line, again of unit slope.The significance of these correlations is discussed in relation to receptor speciation and in regard to other stereoselectivity data available on muscarinic receptorsThe quantitation of the criticality of different chiral centers, made possible here by the very high binding energies involved, should also be applicable to other stereoselective recognition processes (e.g., in enantioselective chromatography). Finally, a fundamental assumption of molecular pharmacology and QSAR, i.e., that a given structural feature always contributes a constant amount to the overall binding energy, is questioned in view of the above findings, which indicate that the contribution increases with the overall affinity, a feature which might be applicable to all pharmaca, not just to those containing chiral molecules.
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    Calmodulin discriminates between the two enantiomers of the receptor-operated calcium channel blocker sk&f 96365: A study using 1H-NMR and chiral HPLC (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 229-232 
    Details
    ISSN: 0899-0042
    Keywords: receptor-operated calcium channel antagonist ; 1H NMR ; chiral HPLC ; calmodulin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H nuclear magnetic resonance at 360 MHz shows that SK&F 96365 (1-{β-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl}-1H- imidazole hydrochloride), an antagonist of mammalian receptor-operated calcium channels, interacts with the calcium-binding regulatory protein calmodulin (CaM). This may be inferred by a number of chemical shift changes in the spectrum of the calcium-saturated protein induced by addition of the compound. Moreover, two well-resolved singlets corresponding to the 2-proton of the SK&F 96365 imidazolium moiety are observed in the spectrum over a wide range of protein:compound ratios. Separation of rac SK&F 96365 into its two enantiomers by high-performance liquid chromatography on a cellulose tris (4-methylbenzoate) column enabled us to show that the doubling of this NMR signal in the presence of CaM is due to a propensity of the protein to distinguish between the two optical isomers of the compound.
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    Stereoselective interaction of an azole antifungal agent with its target, lanosterol 14α-demethylase (cytochrome p-45014dm): A model study with stereoisomers of triadimenol and purified cytochrome p-45014dm from yeast (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 10-15 
    Details
    ISSN: 0899-0042
    Keywords: substrate-binding site ; structure-function relationship ; antifungal activity ; hemoprotein ; diniconazole ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of the four triadimenol stereoisomers on the purified yeast lanosterol 14α-demethylase (cytochrome P-45014DM), the primary target of azole antifungal agents, was studied. (1S,2R)-Triadimenol was the most potent demethylase inhibitor and bound quantitatively to the enzyme below 0.05 μM. This isomer also interfered with the chemical reduction of cytochrome P-45014DM and the binding of CO to the cytochrome. The other isomers showed a lower inhibitory effect on the enzyme, and the order of activity was (1R,2R) 〉 (1R,2S) ≧ (1S,2S). Based on these findings and the reported preferred conformations for the triadimenol stereoisomers (Anderson, N.H. et al., Pestic. Sci. 15:310-316, 1984), it is predicted that orientation of the hydrophobic tert-butyl and p-chlorophenyl groups relative to the azole nitrogen is important to fit the antifungal agent in the active site of the demethylase.
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    The stereochemical resolution of the enantiomers of aspartame on an immobilized α-chymotrypsin hplc chiral stationary phase: The effect of mobile-phase composition and enzyme activity (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 32-37 
    Details
    ISSN: 0899-0042
    Keywords: aspartame stereoisomers ; chiral separations ; column liquid chromatography ; chymotrypsin on silica ; binding sites ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective and diastereoselective resolutions of the stereoisomers of Nα-aspartyl-phenylalanine 1-methyl ester (APME) have been accomplished on an HPLC chiral stationary phase based upon α-chymotrypsin (the ACHT-CSP) with observed enantioselectivities (α1) for the DL-/LD-enantiomers of as high as 29.17 and for the DD-/LL-enantiomers of as high as 28.97. In addition, the effect on the chromatographic retention of the APME stereoisomers of the activity of the ACHT and the composition of the mobile phase - structure of the anionic component, molarity, and pH - have been studied. The results of this study suggest that the aspartyl moiety and/or the aspartyl-phenylalanine amide linkage play key roles in the observed enantioselectivity; the APME stereoisomers containing L-phenylalanine, i.e., DL- and LL-APME, bind at a different site in the ACHT molecule (the L-Phe site) than the APME stereoisomers containing D-phenylalanine (the D-Phe site); and the observed enantioselectivity is a measure of the difference in the binding affinities at the two sites rather than the consequence of differential affinities at a single site.
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    Reversed-Phase LC resolutions of chiral antiarrhythmic agents via derivatization with homochiral isothiocyanates (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 43-51 
    Details
    ISSN: 0899-0042
    Keywords: mexiletine ; flecainide ; tocainide ; propafenone ; chirality ; enantiomers ; HPLC ; homochiral derivatization ; isothiocyanates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The search for new antiarrhythmic agents has been intense, because the established drugs for the treatment of cardiac arrhythmias are neither uniformly effective nor well-tolerated. Among the recently introduced new anti-arrhythmic agents are tocainide (TOC), mexiletine (MEX), flecainide (FLE), and propafenone (PRO). Each of these drugs is a chiral amine used clinically as the racemic mixture. We have examined the high-performance liquid chromatographic chiral resolution of the above four drugs via derivatization with homochiral derivatizing agents (HDAs). The amino functionality of the drugs was reacted with four homochiral isothiocyanates, 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate (TAGIT), (R)-α-methylbenzyl isothiocyanate (RAMBI), (S)-1-(1-naphthyl)ethyl isothiocyanate (SNEIT), and (R)-1-(2-naphthyl)ethyl isothiocyanate (RBEIT). Complete separation of the two peaks (resolution factor R = 1.5) was achieved with all four HDAs for TOC, with TAGIT, RBEIT, and RAMBI for MEX, with TAGIT and SNEIT for PRO, and only with TAGIT for FLE. SNEIT was used to develop analytical procedures for the determination of the enantiomeric composition of TOC in human urine and blood serum. The four HDAs offer several advantages over many other HDAs and should be useful in studies of enantioselective drug action and disposition.
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530020201
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    Stereoselective arylpropionyl-CoA thioester formation in vitro (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 67-73 
    Details
    ISSN: 0899-0042
    Keywords: arylpropionic acid ; coenzyme A thioester ; inversion ; ibuprofen ; fenoprofen ; flurbiprofen ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The inversion from R- to S-enantiomer that occurs for some arylpropionic acids may have both toxicological and therapeutic implications. To characterize some properties of this inversion, arylpropionyl-CoA thioester formation was studied in rat tissue homogenates and subcellular fractions for the enantiomers of fenoprofen, ibuprofen, and flurbiprofen. Thioesters were formed from (R)-fenoprofen (64%) and (R)-ibuprofen (33%) but not from the corresponding S-enantiomers or the enantiomers of flurbiprofen. This correlates with the extensive inversion of fenoprofen and ibuprofen and lack of inversion of flurbiprofen in vivo. Subcellular fractions from rat liver showed thioester formation to occur in mitochondria and microsomes but not cytosol. Once formed, the thioesters were readily racemized by whole rat liver homogenate, mitochondria, and cytosol, but only partially inverted (S:R = 0.3) in microsomes. Thioester formation from fenoprofen and ibuprofen was studied in tissue homogenate obtained from liver, diaphragm, kidney, lung, skeletal muscle, smooth muscle, fat, caecum, and intestines. The liver was at least 50-fold more efficient than the other tissues studied and would be expected to be a major organ of enantiomeric inversion. Our data support the hypothesis that R- to S-enantiomeric inversion of arylpropionic acids proceeds via the stereoselective formation of CoA thioesters followed by enzymatic racemization and hydrolysis of the thioesters to regenerate free acid.
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    2H-NMR resolution of the methylenic isotopomers of ethanol applied to the study of stereospecific enzyme-catalysed exchange (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 85-89 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric resolution ; site-specific isotope fractionation ; 2H-NMR ; ethanol ; enzymic exchange ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have shown that site-specific natural isotope fractionation of hydrogen studied by NMR (SNIF-NMR) is an important source of information on the mechanistic and environmental effects which govern the photosynthesis of sugars and their fermentation into ethanol. Three isotope ratios associated with the methyl, methylene, and hydroxyl sites of ethanol are determined in achiral media. In this study we show that complementary information about possible stereospecific mechanisms involving the methylenic hydrogens is also rendered accessible by 2H-NMR enantiomeric resolution. The synthesis of mandelate esters enables exchange between the pro-R site of ethanol and water to be investigated. Simultaneous access to the three site-specific isotope ratios of the ethyl group is obtained at isotopic dilutions close to the natural ones. Mediation of the exchange by the enzymic system alcohol dehydrogenase-α-lipoyldehydrogenase and by the yeast Saccharomyces cerevisiae are compared. The progress of the reaction can be followed quantitatively as a function of time and the occurrence of glycolytic metabolism of endogeneous materials by yeast can be substantiated in a one-pot experiment.
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    Resolution of derivatized acids and amines on JTB-X: A new urea bonded chiral stationary phase (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 124-127 
    Details
    ISSN: 0899-0042
    Keywords: anti-inflammatory drugs ; chiral drugs ; derivatized amino acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new urea-bonded chiral stationary phase has been developed in our laboratory. This bonded phase has been shown to resolve N-terminal substituted amino acids and the carboxyl derivatized anti-inflammatory drugs. Typical α-value for dinitrobenzoyl phenylglycine was 1.7. Values for derivatized ibuprofen, naproxen, and fenoprofen were 2, 1.84, and 1.6, respectively. Further application of these studies to biologically active compounds such as peptides and drugs is in progress.
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    URL: http://dx.doi.org/10.1002/chir.530020210
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    Enantioselective hydrolysis of oxazepam 3-acetate by esterases in human and rat liver microsomes and rat brain s9 fraction (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 150-155 
    Details
    ISSN: 0899-0042
    Keywords: oxazepam ; 3-O-acyloxazepam (oxazepam 3-acetate) ; diazepam ; N-desmethyldiazepam ; enantiomers ; esterases ; rat brain S9 fraction ; rat liver microsomes ; human liver microsomes ; enantioselective hydrolysis ; chiral stationary phase ; high-performance liquid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rates of hydrolysis of racemic and enantiomeric oxazepam 3-acetates (OXA) by esterases in human and rat liver microsomes and rat brain S9 fraction were compared. When rac-OXA was the substrate, esterases in human and rat liver microsomes were highly enantioselective toward (R)-OXA. In contrast, esterases in rat brain S9 fraction were highly enantioselective toward (S)-OXA. Hydrolysis rates of rac-OXA were highly dependent on the amount of esterases used. At 0.05 mg protein equivalent of esterases and 150 nmol of rac-OXA per ml of incubation mixture, the (R)-OXA was hydrolyzed 3.6-fold and 18.5-fold faster than (S)-OXA by rat and human liver microsomes, respectively. The specific activities (nmol of OXA hydrolyzed/mg microsomal protein/min) of liver microsomes in the hydrolysis of enantiomerically pure (R)-OXA were approximately 120 (rat) and 1,980 (human), and in the hydrolysis of enantiomerically pure (S)-OXA were 4 (rat) and 7 (human), respectively. In the incubation of rac-OXA with rat brain S9 fraction, (S)-OXA was hydrolyzed ∼6-fold faster than (R)-OXA. Results also indicated an enantiomeric interaction in the hydrolysis of rac-OXA by esterases in rat and human liver microsomes; the presence of (R)-OXA stimulated the hydrolysis of (S)-OXA, whereas the presence of (S)-OXA inhibited the hydrolysis of (R)-OXA. In rat brain S9 fraction, the presence of (R)-OXA inhibited the hydrolysis of (S)-OXA, whereas the presence of (S)-OXA appeared to have stimulated the hydrolysis of (R)-OXA.
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    URL: http://dx.doi.org/10.1002/chir.530020305
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    Species differences in the generation of the chiral sulfoxide metabolite of albendazole in sheep and rats (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 156-160 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separation ; sulfoxides ; albendazole ; metabolism ; rat ; sheep ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The prochiral anthelmintic drug albendazole was administered orally to sheep and rats. Blood samples were taken at standardized intervals during the time course of the plasma kinetics: 18 h in rats and 48 h in sheep. The enantiomeric ratio of the sulfoxide metabolite was determined by means of HPLC on a chiral stationary phase, the chiral selector of which was a N-3,5-dinitrobenzoyl derivative of (S)-tyrosine. Two enantiomers were detected in both animal species but their ratios were inverted in rat vs. sheep. The evolution of the ratio is turned from a racemate at 15 min to 60(-):40(+) at 12 h in rats, while it moved from 23(-):77(+) at 3 h to 4(-):96(+) at 36 h after administration in sheep.
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    Investigation of the chiral recognition by “Brush-Type” phases in liquid chromatography using crystal structure analyses of diastereomeric 1:1 complexes of a π-donor and a π-acceptor derivative of leucine (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 185-189 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; 3,5-dinitrobenzoyl group ; chiral recognition mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R,S)-N-Acetyl-leucine-2-naphthylamide can be resolved into its enantiomers on a (S)-DNBLeucine chiral stationary phase. The mechanism of this separation was investigated using as model complexes the 1:1 S,S- and the 1:1 R,S-cocrystals of the above naphthylamide and N-3,5-dinitrobenzoylleucinemethylamide, a soluble analogue of the stationary phase. The observed enantiomeric elution order can be rationalized from their X-ray data.
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    URL: http://dx.doi.org/10.1002/chir.530020310
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    Announcements (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 205-205 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530020314
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    Pheromone, 76. Synthese der Enantiomeren von 10-Methyldodecylacetat und 12-Methyltetradecylacetat, chiralen Pheromonkomponenten von Adoxophyes-Arten (Lepidoptera: Tortricidae) (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 829-831 
    Details
    ISSN: 0170-2041
    Keywords: Pheromones ; Adoxophyes spp. ; 10-Methyldodecyl acetate ; 12-Methyltetradecyl acetate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pheromones, 76. Synthesis of the Enantiomers of 10-Methyldodecyl Acetate and 12-Methyltetradecyl Acetate, Chiral Pheromone Components of Adoxophyes Species (Lepidoptera: Tortricidae)From enantiomeric (R)-(-)- and (S)-(+)-2-methylbutyl bromide (3), available by resolution of (R)-(-)-phenylglycinol amides of rac-2-methylbutanoic acid, and from enantiomeric 6-methyloctyl bromide (7) the corresponding phosphonium salts were obtained. Wittig olefination yielded the optically active methyl-branched olefinic THP ethers 12 and 13, hydrolysis, catalytic hydrogenation, and acetylation gave rise to the formation of the chiral title compounds (R)-(-)- and (S)-(+)-10-methyldodecyl acetate (1) and (R)-(-)- and (S)-(+)-12-methyltetradecyl acetate (2).
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    Total synthesis of methynolide (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 789-793 
    Details
    ISSN: 0170-2041
    Keywords: Methynolide ; Macrolides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper the synthesis of methynolide (1), the aglycone of methymycin, a 12-membered macrolide antibiotic is described. We have used the chiral C-1 to C-8 segment 10 which has been combined with the C-9 to C-13 segment 9 to form the carbon skeleton of methynolide. Cyclization of the seco-acid 14 has been accomplished by intramolecular esterification.
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    Amphiphilic carbohydrate-based mesogens, V. Mesogenic 1-O-alkyl-D-glucitols from alkyl D-glucopyranosides (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 811-813 
    Details
    ISSN: 0170-2041
    Keywords: Liquid crystals ; 1-O-Alkyl-D-glucitols ; Glycoside hydroboration ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The endocyclic acetal bonds of alkyl D-glucopyranosides (hexyl to decyl, 1a - e) are regioselectively hydroborated with ethyldiboranes(6) in the presence of 9-methylsulfonyloxy-9-borabicyclo[3.3.1]nonane (MSBBN) after conversion to their 2,3,4,6-tetra-O-diethylboryl derivatives 2a - e. Subsequent deboronations give the mesogenic 1-O-alkyl-D-glucitols 3a - e.
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    Synthesis and structure of some condensed quinazolines (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 815-817 
    Details
    ISSN: 0170-2041
    Keywords: Quinazolines, hydrazino- ; Triazoloquinazolines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation of 2-hydrazino-4(3H)-quinazolinone (1) with bielectrophilic reagents gives the corresponding triazoloquinazolines 8, the structures of which were established by selective synthesis through deamination of their N-amino derivatives. The synthesis of methyl-substituted derivatives of these angular tricyclic systems and their linear isomers was also achieved starting with 3-methyl- and 1-methyl-2-hydrazino-quinazolinone.
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    Synthesen von Galactose-Cluster-haltigen Steroid-DerivatenAuszugweise vorgetragen auf der Chemiedozenten-Tagung, Bielefeld, 7, März 1989. (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 863-869 
    Details
    ISSN: 0170-2041
    Keywords: Glycoconjugates ; Galactosides ; Steroid esters ; Amphiphiles ; Glycopeptides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Galactose-Cluster-Containing Steroid DerivativesThe synthesis of galactose clusters that are linked to a steroid moiety by a peptide-like spacer unit is described. The galactose cluster is obtained by Koenigs-Knorr glycosylation of TRIS-Gly-Fmoc (2b) under Helferich conditions. Peptide and ester bonds are formed after activation of carboxylic acids as diphenylthiophene dioxide (TDO) esters. 6a is synthesized in a convergent way by coupling of (Ac4Gal)3-TRIS-Gly (3e) with cholesteryl TDO succinate (5b). Coupling of (Ac4Gal)3-TRIS-Gly hydrogen succinate (3f) with Gly-O-Chol (5d) by means of EEDQ yields 6d. Reaction of (Ac4Gal)3-TRIS-Gly-SUCC-O-TDO (3g) with 25-hydroxycholesterol leads in a linear sequence to the oxysterol derivative 6f. Selective cleavage of the acetyl groups from galactose units yields the known compound 6b and the new derivatives 6e and 6g.
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    Glycosylation of 2,3-diphenylindole and derivatives  -  Synthesis of O-, N-, and C-glycopyranosides (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 877-881 
    Details
    ISSN: 0170-2041
    Keywords: O-Glycosyl trichloroacetimidates ; Glycosyl bromides ; Glycopyranosyl donors ; Glycosyl acceptors, polyvalent ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of different glycosyl donors with 5-hydroxy-N-methyl-2,3-diphenylindole (1C) led only to O-glycosylation (compounds 6a-c and 8c-α,β). Depending on the O-protection of the glycosyl donors (2a-c, 3b, 4c), the β-products were obtained mainly or exclusively. The corresponding N-unsubstituted indole 1B and donors 2b and 5a, respectively, also yielded only O-glycosylated products (compounds 11b and 13a). Depending on the glycosyl donor (2a or 2c), the N-unsubstituted 5-methoxy-2,3-diphenylindole (1A) led to N- and/or C-glycosides (compounds 16a, 14a-α,β, and 14c-α,β). The structures were assigned with the help of 1H-NMR data of these products or their derivatives.
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    Verbesserte Synthese von N1-Pyridylthiaminpyrophosphat, einem coenzymatisch aktiven Analogon des Thiaminpyrophosphates (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 913-916 
    Details
    ISSN: 0170-2041
    Keywords: N1-Pyridyl analog of thiamine pyrophosphate ; Thiamine pyrophosphate mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Improved Synthesis of N1-Pyridylthiamine Pyrophosphate, a Coenzymatically Active Analog of Thiamine PyrophosphateOur previously published synthesis of the N1-pyridyl analog 1b of thiamine pyrophosphate6) is improved resulting in a remarkably higher yield. Key reaction of this new synthetic pathway is the oxidative degradation of 5-acetylpyridine 8 to the 5-carboxylic acid 11 via the pyridinium compound 10. Improved preparations of other intermediates are also described. The N1-pyridylthiamine pyrophosphate analog 1b has been separated and purified by ion exchange chromatography on Sephadex A-25.
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    Heterocyclische Siebenring-Verbindungen, XXXVI. Synthese und Eigenschaften des 1,4-Benzoxazepins und einiger monosubstituierter Derivate (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 917-921 
    Details
    ISSN: 0170-2041
    Keywords: 1,4-Benzoxazepine, 5-monosubstituted derivatives ; Photoisomerization ; Azetes, 3,4-dihydro- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocyclic Seven-Membered Ring Compounds, XXXVI.  -  Synthesis and Properties of 1,4-Benzoxazepine and of Some Monosubstituted DerivativesO-Alkylation of salicylamide with bromoacetaldehyde diethyl acetal and subsequent thermal ring closure yields the lactam 2, which is converted into the imide chloride 3. Pd(0)-catalyzed dehalogenation of compound 3 with tributyltin hydride leads to the desired 1,4-benzoxazepine (4), a thermally very unstable compound which prefers polymerization to valence isomerization. O-Alkylation of the lactam 2 and S-alkylation of the thiolactam 8 yield the 5-substituted 1,4-benzoxazepines 6 and 9, resp., which are thermally considerably more stable than the parent compound 4. Thus, they are capable of the expected thermal isomerization to the corresponding hydroxyisoquinolines 10 and 11, resp. The photoisomerization of the 1,4-benzoxazepines 4, 6, and 9 leads to the thermally very unstable dihydroazetes 12, 13, and 14, of which only the methylthio compound 14 could be isolated as crystalline compound.
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    Synthese von [1,1,3-Trioxo-1,2-benzisothiazol-2(3H)-yl]keten-S,S-acetalen und deren Hydrazinolyse (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 927-929 
    Details
    ISSN: 0170-2041
    Keywords: Ketene dithioacetals ; Saccharin derivatives ; Carbon disulfide ; Hydrazine hydrate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of [1,1,3-Trioxo-1,2-benzisothiazol-2(3H)-yl]ketene S,S-Acetals and Their Reaction with Hydrazine HydrateThe previously unknown ketene S,S-acetals 2, 3, and 4 are prepared by dithiocarboxylation reaction of methylene-active saccharin derivatives 1 in the presence of sodium hydride/carbon disulfide in dry DMF followed by alkylation. Compounds 2a, 3a, and 4a are treated with hydrazine hydrate (85%) to give 2-hydrazono-3,3-bis(methylthio)propiophenone (6a) and methyl or ethyl pyruvate 6b or 6c, respectively.
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    Natural product chemistry, 139. Synthesis of the natural coumarins (E)-suberenol, cyclobisuberodiene and two other related new coumarins (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 931-933 
    Details
    ISSN: 0170-2041
    Keywords: Heck condensation, palladium-catalysed ; (E)-Suberenol ; (E)-Suberodiene ; (E)-Suberenene ; Cyclobisuberodiene ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total synthesis of (E)-Suberenol (1) was carried out under the conditions of palladium-catalysed Heck condensation. Two other new coumarins, (E)-7-methoxy-6-(3-methyl-1,3-butadienyl)coumarin [(E)-suberodiene] (3) and (E)-7-methoxy-6-(3-methyl-1-butenyl)coumarin [(E)-suberenene] (4) and cyclobisuberodiene (2) were synthesised from (E)-suberenol.
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    Thermal degradation of glycosides, III. Degradation of cardenolide glycosides (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 943-947 
    Details
    ISSN: 0170-2041
    Keywords: Thermal degradation ; Glycosides ; Cardiac glycosides ; Cardenolide glycosides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal degradation of cardenolide glycosides consisting of different sugar moieties and aglycones was examined. On simple heating, the sugar - aglycone linkage of cardenolide glycosides having 2,6-dideoxy sugar moieties in readily cleaved, to afford their genuine aglycones. On the contrary, cardenolide glycosides possessing 6-deoxy sugar moieties are resistant to the degradative reaction. Besides the fission of the glycosidic linkages, some interesting reactions also took place. The pyrolyzed products were isolated by chromatography, and the structures were elucidated by spectroscopic evidence.
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    Monosaccharide mit Stickstoff im Ring, XXXIX. Synthese von modifizierten α-L-Fucosidase-Inhibitoren, die 1,5-Didesoxy-1,5-imino-L-fucit als Basisstruktur enthalten (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 953-963 
    Details
    ISSN: 0170-2041
    Keywords: Deoxyfuconojirimycin ; Amino sugars ; Indolizidine derivatives ; Fucosidase inhibitors ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monosaccharides Containing Nitrogen in the Ring, XXXIX.  -  Synthesis of Analogues of 1,5-Dideoxy-1,5-imino-L-fucitol, Inhibitors of α-L-FucosidaseVariation of the side chain in the 1,3-dithiane derivative 1 of D-galactose leads to a series of analogues of 1,5-dideoxy-1,5-imino-L-fucitol (deoxyfuconojirimycin) (33), which are potent inhibitors of α-L-fucosidase. Cleavage of the dithioacetal in 5 followed by reduction of the aldehyde 6 and deblocking results in 1,5-dideoxy-1,5-imino-L-galactitol (8). The aldehyde 6 is converted by Wittig reaction to 10 and 14 via 9 and 13, which are homologues of 1,5-dideoxy-1,5-imino-L-fucitol (33). Cyclization of the Wittig product 15 yields the γ-lactam 18. After reduction of the acetylated γ-lactam 19 and subsequent deblocking the trihydroxyindolizidine 24 is obtained, which is an analogue of castanospermine with L-fuco configuration. The chloride 30, which is available from 27, can be converted by intramolecular substitution and removal of the blocking groups to the bicyclic aziridine derivative (3R,4S,5R,6S) -1-azabicyclo[4.1.0]heptane-3,4,5-triol (32). First results on the inhibitory activities of all new analogues on α-L-fucosidase are presented.
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    Antibiotics from gliding bacteria, XLII. Chemical modification of sorangicin A and structure  -  Activity relationship I: Carboxyl and hydroxyl group derivatives (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 975-988 
    Details
    ISSN: 0170-2041
    Keywords: Antibiotics ; Sorangicin A derivatives ; Structure - activity relationship ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of selectively protected sorangicin A derivatives and their application in the modification of the hydroxyl groups and the carboxyl group in sorangicin A (1) is described. Esters, amides, and sorangicins modified at the hydroxyl groups were prepared and their activities against Staphylococcus aureus, Escherichia coli, and their in vitro inhibition of RNA polymerase were examined. Although no sorangicin A derivatives with superior biological activity were observed, some derivatives completely retained their antibiotic activity or were slightly improved in their activity with certain strains.
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    Heterocyclische β-Enaminoester, 53. Neue 5,8-Dihydropyrido- und 4H-Pyrano[2,3-d]pyrimidine (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 995-999 
    Details
    ISSN: 0170-2041
    Keywords: 1,4-Dihydropyridines ; 5,8-Dihydropyrido[2,3-d]pyrimidines ; Pyrido[2,3-d:6,5-d′]dipyrimidine ; 5H-Pyrano[2,3-d]pyrimidine ; Sulfamides, 1,4-dihydropyridinyl ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocyclic β-Enamino Esters, 53.  -  Novel 5,8-Dihydropyrido- and 5H-Pyrano[2,3-d]pyrimidinesThe 1,4-dihydropyridine enamino esters 1a and 4 react with phenyl isocyanate to afford the ureas 2 and 5, resp., which are cyclized to yield the 5,8-dihydropyrido[2,3-d]pyrimidines 3 and 6, resp., while the 1,4-dihydropyridine bisenamino ester 7a gives accordingly, via bisurea 8, the pyrido[2,3-d:6,5-d′]dipyrimidine 10. The 2-amino-4H-pyran-3-carboxylate 11 is smoothly phosphorylated to form 12. Treatment of 12 with phenyl isocyanate results in a ring closure to the 4H-pyrano[2,3-d]pyrimidine 14. Similarly and according to this principle, the 5,8-dihydropyrido[2,3-d]pyrimidine 16 is smoothly formed upon treatment of the iminophosphorane 15 with phenyl isocyanate, while the 2,6-diamino-1,4-dihydropyridine 7b after phosphorylation affords the mono-iminophosphorane 17, which undergoes cyclization with isocyanate to the 5,8-dihydropyrido[2,3-d]pyrimidine 18. With isopropylsulfamoyl chloride 1b and 7a form the mono- and bissulfamides 20 and 21, resp., which could not be cyclized further.
    Type of Medium: Electronic Resource
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    EPC-synthesis and fungistatic activity of a gloeosporone analog with an ω-hydroxybutyl instead of the pentyl side chain on the macrocyclic ring (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1007-1012 
    Details
    ISSN: 0170-2041
    Keywords: Gloeosporone, analog of ; Colletotrichum gloeosporioides ; Oxidation, alkyne → 1,2-diketone ; Antifungal agent ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-5′-Oxa-gloeosporone (2), an analog of the natural germination self-inhibitor (-)-gloeosporone (1), is synthesized, largely following our previously published route to the parent compound. Thus, the hydroxybutyl side chain of 2 was introduced by hydroboration of a butenyl group (→ 14) which had been carried along throughout the synthesis up to the stage of the 14-membered yne-lactone 13. Silyl protection (→ 15), oxidation of the acetylene to a 1,2-diketone moiety (→ 16), and deprotection with spontaneous intramolecular hemiacetal formation completed the synthesis of (+)-2. The (+)-oxa-gloeosporone 2 exhibits an in vitro and in vivo antifungal activity spectrum with 14 microorganisms very similar to both the natural (1) and the unnatural enantiomer (ent-1) of gloeosporone, indicating that neither the sense of chirality nor the side-chain structure is important for the mode of action.
    Additional Material: 1 Tab.
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    Chemoenzymatische „Chiral-Pool“-Synthese von (+)-exo-Brevicomin aus Kohlenhydraten mit Fructose-1,6-diphosphat-Aldolase (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1019-1024 
    Details
    ISSN: 0170-2041
    Keywords: Fructose 1,6-diphosphate ; (+)-exo-Brevicomin ; Aldol reaction, enzymatic ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemoenzymatic “Chiral-Pool” Synthesis of (+)-exo-Brevicomin from Carbohydrates Using Fructose 1,6-Diphosphate AldolaseFructose-1,6-diphosphate aldolase (EC 4.1.2.13) catalyzes the stereospecific aldol reaction between 1,3-dihydroxyacetone phosphate (4) and 5-oxohexanal (3) or its 5-dithiane-protected analog 8. The products of the aldol reactions are dephosphorylated with acid phosphatase (EC 3.1.3.2). Whereas the aldol adduct of 3 cyclizes spontaneously to give the bicyclic brevicomin precursor 3, the adduct of 8 first has to be deprotected with sulfuryl chloride and wet silica gel. The resulting bicyclic α-hydroxy ketone 3 is reduced with LiAlH4 to form the 1,2-diol 14 which is then deoxygenated to give the vinyl compound 17 by treatment of the corresponding dixanthate 15 with tributyltin hydride or by treatment of the corresponding mesylate 16 with sodium naphthalenide. The olefin 17 is finally converted to (+)-exo-brevicomin (1) by hydrogenation with diimide.
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    Darstellung 2-methoxysubstituierter Pyrrole durch intramolekulare Aza-Wittig-Reaktionen (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1037-1043 
    Details
    ISSN: 0170-2041
    Keywords: Aza-Wittig reaction ; Pyrromethenone ; Pyrroles, 2-methoxy-substituted ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of 2-Methoxy-Substituted Pyrroles by Aza-Wittig Reactionsα-Halo ketones and dimethyl malonate can be transformed by Knoevenagel condensation and nucleophilic displacement of halogen with sodium azide into the azide esters 10. These azides undergo ring closure to 2-methoxy-substituted pyrroles 11 by intramolecular Aza-Wittig reaction.
    Additional Material: 1 Tab.
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    Enzymatische Acetylierung von (±)-1-Phthalimido-2-propanol (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1045-1046 
    Details
    ISSN: 0170-2041
    Keywords: Acetylation, enzymatic ; 2-Propanol, (+)-1-phthalimido ; Propane, (+)-2-acetoxy-1-(phthalimido)- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enzymatic Acetylation of (±)-1-Phthalimido-2-propanol1-Phthalimido-2-propanol [(±)-1] is an N-protected derivative of 1-amino-2-propanol. By irreversible enzymatic acetylation of the racemate (±)-1, (+)-2-acetoxy-1-(phthalimido)propane [(+)-2] and (+)-1-phthalimido-2-propanol [(+)-1] have been isolated on a preparative scale in good optical and chemical yields. Both optically active compounds are useful chiral intermediates.
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    URL: http://dx.doi.org/10.1002/jlac.1990199001188
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    Lignanglucoside aus Wurzeln von Urtica dioica (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1205-1213 
    Details
    ISSN: 0170-2041
    Keywords: Lignan glucosides, trimethylsilyl derivatives ; Urtica dioica, root extracts ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lignan Glucosides from Roots of Urtica dioicaLignan glucosides isolated from stinging nettle roots (Urtica dioica) were separated by GC on short glass capillary columns (5-6 m) after appropriate derivatization. By use of mass spectrometry (GC/EI-MS, EI-MS, LSI-MS) and NMR spectroscopy, 11 lignan glucosides were identified, 5 of which were previously unknown. Mixtures of isomeric lignan glucosides which could not be separated by GC were investigated by two-dimensional NMR methods. The spectra allowed the identification of the single components. Mass spectra of the trimethylsilylated glucosides show typical fragments which enabled us to decide if the glucose was attached to an alcoholic or phenolic hydroxy group of the aglycone. The nature of the aglycones could be also deduced from the spectra.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.1990199001218
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    Stereoselective synthesis of alcohols, XXXVI. Stereoselective generation of homoallyl alcohols having quaternary stereogenic centers (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1243-1248 
    Details
    ISSN: 0170-2041
    Keywords: Allylboration reaction ; Diastereoselection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: E- and Z-γ,γ-disubstituted allylboronates 12 have been generated by the carbocupration of alkynes and subsequent homologation. These allylboronates add to aldehydes, forming the homoallyl alcohols 13 and 14 with 88-99% simple diastereoselectivity. The highest diastereoselectivity was obtained with α-branched aldehydes.
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    Pheromone synthesis, CXXI. Synthesis of (4R*,5R*,6S*,7E,9E)-4,6,8-trimethyl-7,9-undecadien-5-ol and its isomers to determine the relative stereochemistry of the female specific compound of the woodroach Cryptocercus punctulatus (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1249-1255 
    Details
    ISSN: 0170-2041
    Keywords: Chiral centers, contiguous ; Dienols ; Pheromones ; Cryptocercus punctulatus ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By synthesizing some isomers of 4,6,8-trimethyl-7,9-undeca-dien-5-ol, (4R*,5R*,6S*,7E,9E)-relative stereochemistry was assigned to the isomer isolated as the female specific compound of the tergal glands secretion of the woodroach Cryptocercus punctulatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1990199001224
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    A short route to 3′-deoxy-3′-fluorothymidine (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1137-1139 
    Details
    ISSN: 0170-2041
    Keywords: Fluorination ; Thymidine, 3′-deoxy-3′-fluoro- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 5-OH-protected methyl glycosides 2 and 3 were epimerized to give the corresponding epimers 6 and 7 via an oxidation-reduction procedure. Reaction of 6 with diethylamino-sulfur trifluoride (DAST) afforded the fluoro sugar 8, which was coupled with thymine to give 3′-deoxy-3′-fluorothymidine (12) after deprotection with saturated ammonia in methanol.
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    URL: http://dx.doi.org/10.1002/jlac.1990199001206
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    Variceramides, three new sphingolipids from the marine sponge Ircinia variabilis (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1141-1142 
    Details
    ISSN: 0170-2041
    Keywords: Sponges ; Ceramides ; Sphingolipids ; Ircinia variabilis ; Variceramides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From the marine sponge Ircinia variabilis, three new ceramides, variceramides 1a-3a, have been isolated. Their structures were deduced from spectroscopic studies and by acid hydrolysis.
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    URL: http://dx.doi.org/10.1002/jlac.1990199001207
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    Synthesis of functionalized pyridines by michael addition of benzoyl(thioacetanilides) to arylmethylenemalononitriles and ethyl α-cyanocinnamates (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1147-1150 
    Details
    ISSN: 0170-2041
    Keywords: Pyridine derivatives, 2-thioxo- ; Thioacetanilides ; Cinnamates, α-cyano- ; Malononitriles, arylmethylene- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of substituted 2-thioxopyridines from benzoyl(thioacetanilides) 1 and arylmethylenemalononitriles or ethyl α-cyanocinnamates 2 is described. The reaction of 1 with 2b, c gives rise to derivatives of tetrahydro- 5 and dihydro-6-thioxopyridines 6. A 4,5-cis configuration of 5 is proposed on the basis of the analysis of the vicinal coupling constants.
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    Synthese von 4-Acetamido-3,7-anhydro-2-azi-1,2,4-tridesoxy-D-glycero-D-gulo-octitol, einem potentiellen Photoaffinitätsreagens mit guter Affinität zu menschlicher β-Hexosaminidase (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1261-1264 
    Details
    ISSN: 0170-2041
    Keywords: Diazirines ; Photoaffinitylabelling ; β-Hexosaminidases ; Carbohydrates ; C-Glycosides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 4-Acetamido-3,7-anhydro-2-azi-1,2,4-trideoxy-D-glycero-D-gulo-octitol a Good Competitive Inhibitor and Potential Photoaffinity Reagent for Human β-HexosaminidaseUsing the known 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl cyanide 2 the corresponding heptonic acid was prepared via its amide by NO2 treatment. Chain extension to yield 5,6,8-tri-O-acetyl-3,7-anhydro-1,4-dideoxy-4-phthal-imido-D-glycero-D-gulo-oct-2-ulose (6) was carried out by condensing the heptonic acid chloride 5 with Meldrum's acid. Compound 6 was finally converted into 4-acetamido-3,7-anhydro-2-azi-1,2,4-trideoxy-D-glycero-D-gulo-octitol (8) by conventional methods. This compound, being an enzyme resistant analog of a glucosaminide, was shown to be a good competitive inhibitor for lysosomal β-hexosaminidase (2-acet-amido-2-deoxy-β-D-hexoside acetamidodeoxyhexohydrolase, E.C. 3.2.1.52) and a potential photoaffinity reagent.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.1990199001226
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    Total synthesis of mycinolide-V (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 23-29 
    Details
    ISSN: 0170-2041
    Keywords: Mycinolide-V ; Macrolides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first synthesis of mycinolide-V (1) is reported. 1 is the aglycon of mycinamycin-V, a 16-membered macrolide antibiotic. The synthesis starts from a C-3/C-9 segment, which has been extended to a C-1/C-10 building block, and subsequently condensed with a C-11/C-17 segment.
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    URL: http://dx.doi.org/10.1002/jlac.199019900104
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    1,4-pentadien-3-ones, 31. 1-(1-cyclohexenyl)-1-propen-2-ones: Synthesis, properties, and stereoselective formation of 3-aryl-4-(1-cyclohexenylcarbonyl)perhydro-1-naphthalenones by sequential michael reaction (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 7-14 
    Details
    ISSN: 0170-2041
    Keywords: 1,4-Pentadien-3-one ; 1-Propen-2-one, 1-(1-cyclohexenyl)- ; Aldol reaction ; Michael reaction, stereoselective, sequential ; 1-Naphthalenone, perhydro- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On rearrangement, 1-ethynyl-1-cyclohexanol (1) yields 1-acetyl-1-cyclohexene (2). At -78°C in the presence of LDA, 2 reacts with aldehydes/ketones yielding the aldols 5/8, which are dehydrated to the title compounds 6 or 9. At room temp., a reaction between the lithium derivative of 2 and 6 ensues, yielding the bicyclic products 10. These can also be prepared independently from isolated 6 and 2 with LDA or butyllithium in high yields. The stereochemistry is elucidated by spectroscopic methods, and the minimum energy conformation of 10a is calculated. The stereoselective formation of 10 is explained by a lithium-controlled sequential Michael reaction.
    Additional Material: 1 Ill.
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    Synthesis of fluorinated α-amino ketones, III. Preparation of fluorinated ketone analogues of phenylalanine, lysine, and p-(Guanidino)phenylalanine (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1-6 
    Details
    ISSN: 0170-2041
    Keywords: Fluorinated α-amino ketones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of α-amino mono-, di-, and trifluoromethyl and difluoromethylene ketones and their derivatives is described. A one-pot sequence related to the Dakin-West reaction starts from amino acids and gives the corresponding fluorinated ketone analogues in good yields. The compounds are of interest as potential inhibitors of serine proteases.
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    URL: http://dx.doi.org/10.1002/jlac.199019900101
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    Synthesis of a protected C-11/C-17 segment of mycinolide-V (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 15-21 
    Details
    ISSN: 0170-2041
    Keywords: Enolate alkylation ; Alkoxyalkylation ; Mycinolide-V ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from D-ribonolactone, the cyclopentylidene-protected dihydroxy ester 12 was prepared in five steps. Reaction of its enolate 13 with benzyloxymethyl iodide gave the esters 15 and 16 with modest selectivity. Each of these was converted into the desired mycinolide building block 32 in seven and six steps, respectively.
    Additional Material: 1 Tab.
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    Synthetic microbial chemistry, XXIII. Synthesis of optically active virginiae butanolides A, B, C, and D and other autoregulators from streptomycetes (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 31-37 
    Details
    ISSN: 0170-2041
    Keywords: A-factor ; Autoregulator of differentiation ; Circular dichroism ; MTPA ester ; Virginiae butanolides A, B, C, and D ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optically active A-factor (1), the factor from Streptomyces viridochromogenes (2), the factors from S. bikiniensis and S. cyaneofuscatus (3-5), and virginiae butanolides A (6), B (7), C (8), and D (9) were synthesized starting from (S)-(-)-paraconic acid (10). The absolute configurations of virginiae butanolides A and C were deduced to be (2S,3R,1′R).
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    Biologically active glycosides from asteroidea, XX. Glycosphingolipids from the starfish Asterina pectinifera,1. Isolation and characterization of acanthacerebroside B and structure elucidation of related, nearly homogeneous cerebrosides (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 51-55 
    Details
    ISSN: 0170-2041
    Keywords: Glycosphingolipids ; Cerebrosides ; Acanthacerebroside B ; Starfishes ; Asterina pectinifera ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A ceramide monohexoside, acanthacerebroside B1b,2a), was purified from the water-insoluble lipid fraction of the chloroform/methanol extract of the starfish Asterina pectinifera Müller et Troschel using reversed-phase HPLC. A new method for identification of components of the ceramide by means of HPLC was developed. The separation and structure elucidation of related, nearly homogeneous cerebrosides which behaved as homogeneous compounds is also described.
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    Über Pyridinium-N-phenolat-Betaine und ihre Verwendung zur Charakterisierung der Polarität von Lösungsmitteln, XIII. Erweiterung der empirischen Polaritätsskala ET(30) um 44 organische Lösungsmittel (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 57-61 
    Details
    ISSN: 0170-2041
    Keywords: Solvent polarity ; ET(30) scale ; Pyridinium N-phenoxide betaine dyes, solvatochromic ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyridinium N-Phenoxide Betaines and Their Application for the Characterization of Solvent Polarities, XIII.  -  Extension of the ET(30) Polarity Scale by 44 Organic SolventsEmpirical solvent polarity parameters ET(30), determined by means of the negatively solvatochromic betaine dye 1, are given for 44 organic solvents of current interest (Table 1).
    Additional Material: 1 Tab.
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    Semisynthetische Myxovirescine: Austausch des α-Hydroxycarbonsäure-Segments und Modifikation der Ringgröße (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 69-81 
    Details
    ISSN: 0170-2041
    Keywords: Myxovirescin analoga ; Macrocyclization ; Antibiotic activity ; Myxococcus virescens, Mx v48 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Semisynthetic Myxovirescins: Exchange of the α-Hydroxycarboxylic Acid Segment and Modification of the Ring SizePartial degradation reactions of the macrocyclic lactam-lacton antibiotic myxovirescin A1 (1) yield the key building blocks 2 and 26. From these myxovirescin analoga are reconstituted with various alkyl groups at position C-2 with R and S configuration. Furthermore a ring-contracted (24) and a ring-enlarged (29) macrocycle are synthesized. The growth of E. coli is best inhibited by the natural myxovirescin A1 with a (2S) propyl substitution whilst 24 and 29 do not inhibit the growth of E. coli at all.
    Additional Material: 15 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.199019900111
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    Structural variations of N-acetylneuraminic acid, 15. Synthesis of 9-deoxy-, 7,9-dideoxy-, and 4,7,9-trideoxy-N-acetylneuraminic acid and their behaviour towards CMP-sialate synthase (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 93-97 
    Details
    ISSN: 0170-2041
    Keywords: CMP-sialate synthase ; Sialic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methyl ester of N-acetylneuraminic acid β-methyl ketoside (Neu5Ac1Me-2β-Me) (1) is used as common starting material for the synthesis of the title compounds. Combined derivatization reactions with reagents thiophosgene, p-cresol, benzoyl chloride, and acetic anhydride/pyridine lead to the thiocarbonate derivatives 2, 6-8, and 12. Further transformation with iodomethane yields the 9-iodo compounds 3, 9, and 13, which are reduced by tributyltin hydride to the deoxy derivatives 4, 10, and 14. Hydrolysis of 14, 10, and 4 affords the desired 9-deoxy, 7,9-dideoxy-, and 4,7,9-trideoxy-N-acetylneuraminic acids 15 (9-d-Neu5Ac), 11 (7,9-d2-Neu5Ac), and 5 (4,7,9-d3-Neu5Ac), respectively.  -  The sialic acid analogues 11 and 5 were activated by CMP-sialate synthase [E,C.2.7.7.43] to an extent of 30-40 and 50-60%, respectively, relative to N-acetylneuraminic acid.
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    URL: http://dx.doi.org/10.1002/jlac.199019900113
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    Hydroacridine, XIII. Sterischer Verlauf der N-Oxidation von N-Alkyl-Derivaten des (4aα,8aβ,9aβ,10aα)-Tetradecahydroacridins (α-Perhydroacridin)Diese Arbeit wurde auf der 5. rumänischen Konferenz für allgemeine und angewandte physikalische Chemie, Bukarest, 1. -4. September 1976, mitgeteilt. (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 99-100 
    Details
    ISSN: 0170-2041
    Keywords: Amine oxides ; Acridines N-alkylperhydro- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydroacridines, XIII.  -  Steric Course of the N-Oxidation of N-Alkyl Derivatives of ((4aα,8aβ,9aβ,10aα)-Tetradecahydroacridine (α-Perhydroacridine)Diese Arbeit wurde auf der 5. rumänischen Konferenz für allgemeine und angewandte physikalische Chemie, Bukarest, 1. -4. September 1976, mitgeteilt.The oxidation of N-methyl-α-perhydroacridine (1), with hydrogen peroxide at room temperature occurs approximately with 83% by equatorial, and approximately with 17% by axial attack of the oxygen on the nitrogen atom. The oxidations of N-ethyl- (2) and N-benzyl-α-perhydroacridine (3) yield only the N-oxides with axial oxygen (2′a and 3′a, respectively).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900114
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    Thermal valence rearrangements of heterocycles, 3. A key aziridine intermediate of the Δ4-isoxazoline-pyrrole rearrangement (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 109-110 
    Details
    ISSN: 0170-2041
    Keywords: Valence rearrangement, thermal ; Nitrones, 1,3-dipolar cycloaddition of ; Isoxazolines, rearrangement of ; Aziridines, 2-acyl- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Utilizing the spiro[adamantane-Δ4-isoxazoline] precursor 10, a key 2-acylaziridine intermediate (11) has been isolated, thus providing conclusive evidence that an initial ring contraction may be considered to be the first step of the Δ4-isoxazoline-pyrrole rearrangement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900117
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  • 80
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    Transformations starting from biotechnologically available materials, I. A convenient preparative route to 1-oxa-5-azaspiro[2.4]heptane Systems (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 111-112 
    Details
    ISSN: 0170-2041
    Keywords: 1-Oxa-5-azaspiro[2.4]heptane, derivatives ; Epoxidation ; Itaconic acid ; Pesticides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple, efficient procedure for the conversion of N-arylitaconimides 3a - f into novel 5-aryl-1-oxa-5-azaspiro[2.4]-heptane-4,6-diones 4a-f using peroxytrifluoroacetic acid is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900118
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  • 81
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    Über neue Säuren im ostindischen Sandelholzöl (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 119-121 
    Details
    ISSN: 0170-2041
    Keywords: Sandalwood oil, East Indian ; Terpenoic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Acids in the East Indian Sandalwood OilThree new terpenoic acids, dihydro-α-norcurcumenic acid (2), α-bergamotenic acid (3), and dihydro-α-santalic acid (4), could be identified by means of GC-MS and GC-FTIR techniques as genuine constituents of the East Indian sandalwood oil. The former postulated γ-santalic acid (1) could not be detected. Also a series of pyrolytic experiments did not lead to its formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900121
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  • 82
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    Reaktionssteuerung durch die Struktur eines Phasentransfer-Katalysators bei Tribrommethyl-Anion-/Dibromcarben-Umsetzungen (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 125-128 
    Details
    ISSN: 0170-2041
    Keywords: Phase transfer catalysis ; Control of reaction paths ; Onium salts ; Crown ethers ; Michael addition ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of Reactions with Tribromomethyl Anions/Dibromocarbene by the Nature of the Phase Transfer CatalystConversion of (substituted) allyl bromides with bromoform/sodium hydroxide/phase transfer catalyst may be directed towards dibromocarbene addition or substitution by tribromomethyl anion by choice of the catalyst. The observed effects (addition: substitution in the primary step variable between maximally 92:1 and 1:91) are by far the largest reported for specific catalyst influences. Small, hard cations favor the carbene route, sterically shielded and highly delocalized ones favor the substitution process.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900123
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  • 83
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    Synthesis of acyclic analogs of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 145-150 
    Details
    ISSN: 0170-2041
    Keywords: Peptides, muramyl; acyclic analogs of ; 3-Morpholinone intermediates ; Immunostimulants ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of the acyclic MDP analogs 27-37 is described, the carbohydrate moiety of muramic acid being replaced by acyclic amino alcohol structures. Their preparation was accomplished by hydrolytic cleavage of the cyclic, disubstituted 3-morpholinones 2-5 and protection of the free amino group to give the compounds 6-9. Coupling with the dipeptide L-alanyl-D-isoglutamine benzyl ester, cleavage of the N-protecting group, acylation with acyl chains of various lengths and hydrogenation produced the title compounds 27-37. The latter exhibit variable lipophilic character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900125
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  • 84
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    Asymmetric induction of four chiral centers by hetero Diels-Alder reaction of a chiral nitroso dienophile (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 267-270 
    Details
    ISSN: 0170-2041
    Keywords: Asymmetric synthesis ; Diels-Alder reaction ; Hetero Diels-Alder reaction ; Aminocyclitols ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diels-Alder reaction of cis-5,6-diacetoxy-1,3-cyclohexadiene (1), which has a meso configuration, with the chiral nitroso dienophile 2 occurs with induction of four asymmetric centers in very high optical yield (ee = 94%) and leads to the dihydro oxazine 3 (89%). The influence of the reaction temperature on the asymmetric induction was investigated and the absolute configuration of the product determined. Reductive cleavage of the N — O bond of 3 presents a simple route to enantiomerically pure derivatives of (1R)-conduramine A1 (82%).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900148
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  • 85
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    Formation of a benzopyrylium ion and a quinoline from benzofuran (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 277-279 
    Details
    ISSN: 0170-2041
    Keywords: Diazirine ; Carbene ; Cyclopropane ; Benzopyrylium cation ; Quinoline ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chlorophenylcarbene reacts with benzofuran to give the cyclopropane derivative 3, which undergoes thermal opening of the three-membered ring to give the benzopyrylium cation 5. With aniline, 3 forms the quinoline 11 containing two C atoms of the starting compound 1 in positions 2 and 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900150
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  • 86
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    Cyclit-Reaktionen, XVII. Synthese von Pseudodisacchariden und Varianten von Valiolamin und Valiol (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 169-180 
    Details
    ISSN: 0170-2041
    Keywords: Glucosidase inhibitor ; Inositol ; Pseudodisaccharide ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclitol Reactions, XVII.  -  Synthesis of Pseudodisaccharides and of Derivatives of Valiolamine and ValiolEpoxid 8 has been synthesized from 2. Oxirane ring cleavage of 8 yields 1L-6-Amino-6-desoxy-2-C-hydroxymethyl-myo-inositol 11. Analogous epimino compound 19 is obtained by neighbour group participation from inosamine 18. Debenzylation of 19 results in 1L-2,3-Didesoxy-2,3-epimino-4-C-hydroxymethyl-epi-inositol 28 having structural analogy to the α-glucosidase inhibitor conduritol B epoxide. Imino-linked pseudodisaccharide 43 is prepared by condensation of 18 with 36. Ether-linked pseudodisaccharide 49 can be obtained by coupling of 44 and 45.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900129
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  • 87
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    Ozonolyse von Olefinen, I. Ozonolyse von 1,4-Cyclohexadien und säurekatalysierte Folgereaktionen von Primärspaltprodukten (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 185-188 
    Details
    ISSN: 0170-2041
    Keywords: Ozonolysis ; 1,4-Cyclohexadiene ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ozonolysis of Olefins, I.  -  Ozonolysis of 1,4-Cyclohexadiene and Acid-Catalysed Reaction of Primary Cleavage ProductsThe reaction of 1,4-cyclohexadiene (1) with ozone under different reaction conditions was investigated. Complete ozonolysis of 1 in chloroform led to a highly explosive ozonide. Oxidative ozonolysis gave malonic acid in 30% yield, ozonolysis in alcoholic solutions of HCl gave alkyl 3,3-dialkoxypropionates 3 in 60-70% yield and small amounts of the 1,1,3,3-tetraalkoxypropane 4 as well as dialkyl malonate 5. Partial ozonolysis of 1 in HCl/methanol led to a mixture of 3, 5, and the corresponding (Z)-3-hexene derivatives 6a-c. Depending on the reaction time and concentration of HCl, also the two methanol addition products 7b and 7d could be obtained. To verify the structure of these two compounds, 4-methoxycyclohexene (8) was ozonized in HCl/methanol, which gave a mixture of 7a-d.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900131
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  • 88
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    Nucleophile Ringöffnung von 1-Nitro-1-cyclopropancarbonsäure-arylestern mit sterisch geschützter, aber elektronisch wirksamer Carbonyl- und Nitrogruppe. Ein neues Prinzip der Aminosäuresynthese (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 195-201 
    Details
    ISSN: 0170-2041
    Keywords: Cyclopropanes, nucleophilic ring opening of ; Pimelic acid, 6-amino-3-aza- ; β-Turns in peptides ; Peptides ; Amino acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleophilic Ring Opening of Aryl 1-Nitro-1-cyclopropanecarboxylate with Sterically Protected, but Electronically Effective Carbonyl and Nitro Group. A New Principle of Amino Acid SynthesisThe readily available [2,6-di-(tert-butyl)-4-methoxyphenyl] 1-nitro-1-cyclopropanecarboxylate (4) is ring-opened by nucleophilic attack of the amino groups of (S)-α-amino acid esters (products 20-26). Reduction of the nitro group gives rise to derivatives 27-30 of 2,4-diaminobutanoic acid which are connected with a second amino acid through the nitrogen in position 4 (2-substituted 6-amino-3-azaheptanedioic acids). In two cases, these were converted into enantiomerically and diastereomerically pure Freidinger's γ-lactam dipeptides (31, 32), which have previously been shown to mimic a peptide β-turn.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900133
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  • 89
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    Polycyclische Aromatische Alkaloide, V. Synthese von 2-Bromleptoclinidinon (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 205-206 
    Details
    ISSN: 0170-2041
    Keywords: Alkaloid ; Amination, oxidative ; 2-Bromoleptoclinidinone ; Tunicate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polycyclic Aromatic Alkaloids, V. - Synthesis of 2-Bromoleptoclinidinone4-Bromo-2-nitroacetophenone (6) is selectively reduced to the amine 7 by Fe in aqueous acetic acid. Oxidative amination of quinolinequinone 8 with 7 gives 9. Acid-catalyzed cyclization of 9, followed by anellation of a pyridine ring, gives the cytotoxic pentacyclic alkaloid 2-bromoleptoclinidinone (3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900135
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  • 90
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    Natural product chemistry, 134. Syntheses of the natural coumarins gleinene and gleinadiene (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 209-210 
    Details
    ISSN: 0170-2041
    Keywords: Gleinene ; Gleinadiene ; Coumarin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 5,7-dimethoxycoumarins, gleinene (3b) and gleinadiene (2), which naturally occur in Murraya gleinei root bark, have been synthesized in four steps from 7-hydroxy-5-methoxycoumarin (1a) in overall yields of 45% and 19%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900137
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  • 91
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    Synthesis and oxidation of pregna-3,5-dien-20-ols and -20-one and selective reduction of pregna-3,5-dien-20-one (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 213-215 
    Details
    ISSN: 0170-2041
    Keywords: Steroids ; Pregna-3,5-dien-20-one, oxidation, reduction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pregna-3,5-dien-20-one (4) and (20S)- and (20R)-pregna-3,5-dien-20-ol (2 and 3) were synthesized from progesterone. Oxidation of a mixture of 2 and 3 with Jones reagent gave 4, while a large excess of Jones reagent afforded besides 4, 6-oxoprogesterone (5), 6β-hydroxyprogesterone (6) and 5α-pregnane-3,6,20-trione (7). With L-selectride as reducing agent, reduction of 4 led to 2 and 3 in a ratio of about 1:1. However, some reducing agents gave a higher ratio of isomer 3.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900139
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  • 92
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    Synthesis of trialkylsiloxy-substituted and other 5,6-dihydro-4H-1,2-oxazines by hetero diels-alder reactions of nitroso alkenes  -  Preparative scope and diastereoselectivity (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 217-226 
    Details
    ISSN: 0170-2041
    Keywords: 1,2-Oxazine, siloxy-substituted ; Nitroso alkene ; Silyl enol ether ; Hetero Diels-Alder reaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of 5,6-dihydro-4H-1,2-oxazines 3 and 4 is prepared in good yields from silyl enol ethers 1 and nitroso alkenes 2a or 2b, respectively. A systematic variation of substituents reveals preparative scope and limitations of this hetero Diels-Alder reaction with inverse electron demand. The cycloaddition is rather sensitive with regard to steric effects - in particular, large groups at C-1 of the silyl enol ethers 1 completely prevent the reaction. On the other hand, excellent diastereo-selectivities are observed employing appropriately substituted olefins. The presented method for the synthesis of 1,2-oxazines also displays high regio- and periselectivity as is demonstrated by transformations 1r→3r and 13→14.
    Additional Material: 10 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.199019900140
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  • 93
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    Neue Synthesen von 1,3-Oxazinen, Thiazolen und 1,2-Dithiolen (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 239-243 
    Details
    ISSN: 0170-2041
    Keywords: Diazo diketones ; Oxazines ; Thiazoles ; Dithioles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Syntheses of 1,3-Oxazines, Thiazoles, and 1,2-DithiolesThe 2-diazo-1,3-diketones 1 react with thioamides 4 via the acyl ketenes 3, resulting from Wolff rearrangement, to give the 1,3-oxazine-4-ones 10; however, by increasing the electro-philicity of the diazo compounds or the nucleophilicity of the thioamides, the 5-acylthiazoles 9 are obtained. These are derived from the diketocarbene intermediates 2. The structure of 9g was confirmed by X-ray diffraction analysis.  -  The best preparative method for 1,3-oxazinones consists in the dehydratation of the 2,N-diacylacetamides 8, which are readily available from the reaction of diazodiketones with carboxamides.  -  The thionation of 8 or 10 with P4S10 proceeds with spontaneous dehydrogenation, affording high yields of 3-(thiobenzoylimido)-1,2-dithioles 15. The structure of 15a was established by X-ray diffraction analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900143
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    Solution synthesis of a biologically active fragment (33-41) of thymosin β9 (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 249-252 
    Details
    ISSN: 0170-2041
    Keywords: Peptides ; Immunoactive peptides ; Thymus peptides ; Thymosin β9 (33-41) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The C-terminal fragment 33-41 of thymosin β9 is synthesized by solution synthesis, using the strategy of maximum side-chain protection with acid-labile tert-butyl groups and temporary Nα-benzyloxycarbonyl protection during the elongation steps. Part of this peptide is deprotected, coupled to KLH and the conjugate used for the production of antibodies. The biological activities of two fragments and of the nonapeptide are tested in our α-amanitin-inhibited E-rosette assay.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900145
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  • 95
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    N-Geschützte 3-Hydroxypyrrole (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 397-399 
    Details
    ISSN: 0170-2041
    Keywords: 3-Pyrrolols ; Wittig olefination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Protected 3-HydroxypyrrolesStarting from symmetrical imides and (α-haloacetylmethylene)-phosphoranes 2, N-acyl-3-hydroxypyrroles 4 have been prepared by an intramolecular Wittig olefination. The deacylation of 4 was proved using 4 b as an example.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900175
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  • 96
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    Versuche zur Herstellung von 2,6-Bis(2-furyl)-4-phenylpyrylium-tetrafluoroborat (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 401-402 
    Details
    ISSN: 0170-2041
    Keywords: 1,5-Diketones, (2-furyl)-substituted ; Pyrylium salts, (2-furyl)-substituted ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempts toward the Synthesis of 2,6-Bis(2-furyl)-4-phenylpyrylium TetrafluoroborateAn improved synthesis of the 1,5-diketone 3 is reported. Ring closure of 3 with triphenylcarbenium tetrafluoroborate leads only to a mixture of the pyrylium salts 4 and 5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900176
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  • 97
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    Synthese von Undecose-Derivaten als D-Galactose-Analoga zur spezifischen Modifikation Galactose-bindender Proteine (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 271-275 
    Details
    ISSN: 0170-2041
    Keywords: Epoxides ; Diazirines ; Undecoses ; Affinity labelling ; Antibodies ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of Undecose Derivatives as D-Galactose Analogues for Specific Modification of Galactose-Binding ProteinsA series of undec- and dodecoses containing functional groups was obtained from 1,2:3,4-di-O-isopropylidene-α-D-galacto-hexodialdo-pyranose-(1,5) (1) using Wittig and Grignard reactions to bring about chain elongation. The compounds resemble 6-C-alkylated D-galactose derivatives which should have affinity to some galactose-binding proteins. One potential photoaffinity reagent, 8-azi-6,7,8,9,10-pentadeoxy-D-galacto-undecose (12), was prepared from 6,7,9,10-tetradeoxy-1,2:3,4-isopropylidene-α-D-galacto-8-undecosulopyranose-(1,5) (10). Compound 11 is suitable for syntheses of “spacer-modified” oligosaccharides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900149
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  • 98
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    Darstellung und Charakterisierung von diastereomeren (4S)-3-Acetyl-2-aryl-5,5-dimethyl-4-thiazolidincarbonsäuren (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 281-286 
    Details
    ISSN: 0170-2041
    Keywords: Thiazolidine, 4-carboxylic acid ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Characterisation of Diastereomeric (4S)-3-Acetyl-2-aryl-5,5-dimethyl-4-thiazolidinecarboxylic AcidsThe condensation of aromatic aldehydes 1 and D-penicillamine (2) in aqueous methanol gives (4S)-2-aryl-5,5-dimethyl-4-thiazolidinecarboxylic acids 3 with alternating diastereoselectivity in position 2. Acetylation of the products with acetic anhydride in pyridine or in water gives rise to (2S,4S)-3-acetyl-2-aryl-5,5-dimethyl-4-thiazolidinecarboxylic acids 5. Use of a HCl/dioxane system in the reaction of N-acetyl-D-penicillamine (6) with aldehydes made possible the effective preparation of (2R,4S) compounds 8. The diastereomeric compounds 5 and 8 were characterized by 1H- and 13C-NMR data and optical rotation and CD. The results were compared with those compiled from the already synthesized diastereomeric (4R)-3-acetyl-2-aryl-4-thiazolidinecarboxylic acids.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900151
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  • 99
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    Synthesis of polyfunctionally substituted pyridazines (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 293-296 
    Details
    ISSN: 0170-2041
    Keywords: Pyridazine, derivatives ; Pyrazolo-pyridazine, derivative ; Pyrido-pyridazine, derivative ; Isoxazolo-pyridazine, derivative ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyridazines 3, 4, 5, and 7 were obtained by reaction of the hydrazone derivatives 2 with several reagents. By treatment of 5 with acetic acid/hydrochloric acid, the pyrazolo[4,3-c]-pyridazine 6 was formed. The pyrido-pyridazine derivatives 8 and 9 were obtained by reaction of 2 and 3 with malononitrile and ethyl cyanoacetate, respectively, and the isoxazolo-pyridazines 11 by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium ethoxide solution. The intermediate 9 was separated by reaction of 3a, b with hydroxylamine hydrochloride in ethanolic sodium acetate solution.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900153
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    Reactions of organic anions, 164. Formation of gem-dichlorocyclopropanes from perhalomethanes and alkenes in a phase-transfer catalytic (PTC) system (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 297-298 
    Details
    ISSN: 0170-2041
    Keywords: Dichlorocarbene, generation ; gem-Dichlorocyclopropane, formation ; Halogenophilic reactions ; Phase transfer catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perhalomethanes YCCl3 (Y = Cl, Br) react with alkenes in the phase-transfer catalytic system to give gem-dichlorocyclopropanes.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199019900154
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