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  • Organic Chemistry  (7,050)
  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During studies on the biogenesis of betalains (I) in cactus fruits (Opuntia sp.). DL-dopa-1-[14C] and -2-[14C] were incorporated into betanin (III) which was obtained radiopure after crystallization. The specific activity remained constant after conversion to betanidin (IV) and to a neobetanidin derivative (IX). Reaction of radiobetanin with proline afforded indicaxanthin (V) carrying more than 90% of the radioactivity. Dopa (VI) is thus an efficient precursor for betalamic acid (VIII) but not for cyclodopa (VII). Decarboxylation of radiobetanidin and radioindicaxanthin showed that the carboxyl group of dopa remained a carboxyl group in the biotransformation to betalamic acid. It is concluded that the aromatic ring of dopa is cleaved and that re-cyclization involving the nitrogen generates the dihydropyridine moiety. Under the same conditions mevalonic acid, aspartic acid and phenylalanine showed low incorporations. Studies with beet seedlings and DL-dopa-1-[14C], -2-[14C] and DL-tyrosine-1-[14C] afforded similar results but with low incorporations.
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zur Herstellung von Ausgangsprodukten zur Synthese des Javanicins wurden, ausgehend von Vanillin (1) über Methoxyhydrochinon (2), dessen Ester 2a, b und 1, 2, 4-Trimethoxybenzol (2c) mit FRIES'scher Verschiebung, FRIEDEL-CRAFTS-Reaktion und MANNICH-Kondensation eine grössere Anzahl Verbindungen vom Typus 3, 4, 5, 6 hergestellt, welche die neu eingeführten Substituenten in o-, m-, p-Stellung zu den bereits vorhandenen Sauerstoff-Funktionen tragen. Weitere Auf-baureaktionen unter Anwendung von Malonestersynthesen führten zu monocyclischen Präparaten von Typus 20, 21, die z. T. bereits sämtliche C- und O-Atome des Javanicins in der richtigen Anordnung aufwiesen, bisher aber nicht zu Javanicin-Derivaten cyclisiert werden konnten.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 21 (1938), S. 939-953 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
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  • 4
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies on Sulphochlorination of Paraffins. V. Kinetic Studies on the Sulphochlorination of Pure AlkanesulphochloridesThe mixtures of disulphochlorides formed by sulphochlorination of 1-alkanesulphochlorides C4—C9 may be analyzed gaschromatographically after transformation into the corresponding dimethylamides. The individual peaks could be identified in some cases with the aid of pure isomeric disulphochlorides, in other cases they were identified by analogy. The mixtures formed by sulphochlorination of the isomeric heptane sulphochlorides also could be analyzed after transformation into the dimethylamides; the identification of all peaks was possible by comparison of the mixtures obtained from different heptane sulphochlorides.For the alkane sulphochlorides studied the relative rates of sulphochlorination (with reference to n-octane) were determined, and therefore the relative reaction rates of the individual C—H-bonds with reference to one primary C—H-bond of n-octane could be calculated.The results show a geminal or vicinal disubstitution not to take place in noticeable amount. In position 3 or in greater distance the influence of the sulphochloride group on the reactivity of the C—H-bonds is not significant.
    Additional Material: 7 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 36 (1967), S. 304-310 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Unter den Bedingungen der Fischerschen Indolsynthese entstehen aus Lävulinsäureäthylester und entsprechenden Arylhydrazinen 5- und 7-Carboxy- bzw. Äthoxycarbonyl-2-methyl-indolyl-(3)-essigsäureäthylester. Deren Reaktionen (Hydrolyse, Kondensation mit primären Aminen und Hydrazin) sowie die Umsetzung der Hydrazide mit Carbonylverbindungen, Phenylisocyanat, Phenylsenföl und Bromcyan werden beschrieben.
    Additional Material: 4 Tab.
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  • 6
    ISSN: 0899-0042
    Keywords: chiral thiol derivatisation ; diastereomeric derivative ; reversed phase HPLC ; fluorescence detection ; assay validation ; enantiomer pharmacokinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A specific plasma level assay for the enantiomers of α-lipoic acid is described. It makes use of liquid-liquid extraction, chemical reduction to the dithiol enantiomers, and their precolumn chiral derivatisation with o-phthalaldehyde in the presence of D-phenylalanine. The two diastereomeric derivatives are separated by reversed-phase HPLC with fluorescence detection. The working range of the assay is between 15 ng/ml (lower limit of quantitation) and 1,000 ng/ml for either enantiomer. Chirality 9:32-36, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 7
    ISSN: 0899-0042
    Keywords: proton pump inhibitor ; pantoprazole ; stereoselective pharmacokinetics ; genetic polymorphism ; human ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pantoprazole (PAN) is a proton pump inhibitor that is administered as a racemic mixture. The pharmacokinetics of PAN enantiomers were investigated in extensive metabolizers (EMs) and apparent poor metabolizers (PMs) of PAN who received a single 40, 60, or 80 mg oral dose of racemic PAN as enteric-coated formulation. In the EMs, the serum concentrations of (-)-PAN were slightly higher than those of (+)-PAN at each dose level. The (+)/(-) ratios for the area under the concentration-time curve (AUC) and the half-life were 0.58-0.89 and 0.62-0.88, respectively. In the PMs, the serum concentrations of both enantiomers were much higher than those in the EMs at each dose level and significant differences in pharmacokinetics of (+)- and (-)-PAN were observed. The half-lives for (+)-PAN were 2.67-3.77 times longer than those for (-)-PAN. The AUCs for (+)-PAN were 2.65-3.45 times greater than those for (-)-PAN. Therefore, the metabolism of (+)-PAN is impaired to a greater extent than (-)-PAN in the PMs, which resulted in the stereoselective disposition of PAN in the PMs. It has been suggested that the EMs and the PMs of PAN could be differentiated by determining the (+)/(-) enantiomer ratio in serum at one time point, possibly 2-6 h after oral dosing, because the (+)/(-) enantiomer ratios in the PMs were opposite those in the EM subjects. Chirality 9:17-21, 1997 © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1977 (1977), S. 709-726 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclic Cross-Conjugated Bond Systems, 30.  -  13C-Analyses of Methylenenorbornadiene DerivativesIn order to assess the homoconjugative relationship in the methylenenorbornadiene skeleton (3) the 13C-spectra of derivatives with alkyl-, aryl-, cyclopentadienylidene-, and cyano substituents in position 8 as well as with electron-withdrawing groups (CO2CH3, CN, CF3) on the endocyclic C=C-bonds have been analyzed. Comparison with saturated and cross-conjugated reference systems substantiates the low polarisability of the semicyclic C=C-bond in 3 and gives indications that increasing electron attraction in position 8 can intensify the homoconjugation, albeit only slightly.
    Notes: Zur Beurteilung der homokonjugativen Beziehung im Methylennorbornadien-Gerüst (3) werden die 13C-Spektren von Derivaten mit Alkyl-, Aryl-, Cyclopentadienyliden- und Cyanresten in Position 8 und zusätzlichen elektronenziehenden Resten (CO2CH3, CN, CF3) an den endocyclischen C=C-Bindungen analysiert. Der Vergleich mit verschiedenen gesättigten und gekreuzt-konjugierten Referenzsystemen belegt eine stark verringerte Polarisierbarkeit der semicyclischen C=C-Bindung in 3 und liefert Hinweise dafür, daß durch Verstärkung des Elektronenzugs in Position 8 die homokonjugative Wechselwirkung - wenn auch nur wenig - intensiviert werden kann.
    Additional Material: 4 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 479 (1930), S. 26-42 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 10
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interaction in Crystals. 98. Protonated Hexamethylmelamin Salts with Different Anions: Monomeric Tetraphenylborate, Dimeric Trifluoracetate and Polymeric Chloride-DihydrateHexamethylmelamin (2,4,6-tris(dimethylamino)-1,3,5-triazine), on monoprotonation at one of the triazine nitrogens keeps its close to planar skeleton. Its salts with different anions reflect biochemically interesting hydrogen-bridge networks: Crystallization of the hydrochloride from isopropanol solution containing Li⊕ [B⊖(C6H5)4], yields “naked” molecular cations, packed in herringbone fashion in between the lattice-dominating bulky, phenyl-shielded and non-protonable tetraphenylborate anions. From trifluoroacetic acid, crystals with sandwich-like subunits connected by hydrogen-bridged anions [F3CCOO⊖…HOOCCF3] are obtained. The hydrochloride salt, prepared by adding aqueous HCl to a diethylether solution, crystallizes in stacks of triazinium cation dimers with an intermolecular bridge N⊕-H…Cl⊖…H⊕N in between chloride-bydrate strands (…Cl⊖…HOH…O(H)H…Cl⊖…). Together, the structures of the three different hexamethyl-melaminium salts further illustrate the influence of anions on the crystallization of protonated nitrogen heterocycles and complement that of counter cation cation solvation in molecular anion salts.
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