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  • Organic Chemistry  (191)
  • Wiley-Blackwell  (191)
  • American Society of Hematology
  • 1
    Digitale Medien
    Digitale Medien
    Enzymatic Cleavage of N-Phenylacetyl-Protected Ethanolamine Phosphates (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1215-1220 
    Details
    ISSN: 0947-3440
    Schlagwort(e): L-glycero-α-D-manno-Heptopyranosides ; Ethanolamine phosphates ; Phenylacetyl, enzymatic cleavage of ; Carbohydrates ; Glucosylations ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Immobilized penicillin-G acylase mediated removal of the N-phenylacetyl protective group in ethanolamine phosphates 7 and 9 furnished compounds 8 and 10, respectively. Deblocking of N-phenylacetyl-protected ethanolamine phosphate heptosyl disaccharide 22, a protected spacer-containing fragment of the inner-core lipopolysaccharide region of Neisseria meningitidis, immunotype L3 was readily accomplished with penicillin-G acylase, yielding target dimer 2. Disaccharide 22 was accessible by elongation of ethyl 1-thio-L-glycero-α-D-manno-heptopyranosyl donor 13 with acceptor 14 under the influence of N-iodosuccinimide/triflic acid. Protective group manipulations, phosphorylation with the reagent 2-cyanoethyl 2-(phenylacetylamino)ethyl N,N-diisopropylphosphoramidite (5) and deprotection furnished LD-Hepp dimer 22.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970625
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  • 2
    Digitale Medien
    Digitale Medien
    Synthesis and Conformational Analysis of 2′-Deoxy-2′-(3-methoxybenzamido)adenosine, a rational-designed inhibitor of trypanosomal glyceraldehyde phosphate dehydrogenase (GAPDH) (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 631-644 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of 2′-benzamido-2′-deoxyadenosine analogues were synthesized in an effort to find new lead structures for the treatment of sleeping sickness. The 2′-deoxy-2′-(3-methoxybenzamido)adenosine (1h) was proved to be a selective inhibitor of the parasite glyceraldehyde 3-phosphate dehydrogenase which confirms the modeling studies. The solution-state conformation of 2′-(thiophene-2-carboxamido) analogue 1d demonstrates a 2′-endo conformation, an orientation of the thiophene ring under the ribose moiety, and the base part occupying a ‘syn’/‘anti’ equilibrium.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19940770306
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  • 3
    Digitale Medien
    Digitale Medien
    13C-NMR. Study on Isoalloxazine and Alloxazine Derivatives (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 367-379 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of isoalloxazine and alloxazine derivatives have been investigated by 13C-NMR. The synthesis of selectively 13C-enriched derivatives made it possible to assign unambiguously the signals due to the quaternary carbon atoms at position 4, 4a and 10a of the isoalloxazine ring system. The assignment of the other resonances was ensured by the use of selectively deuteriated and chemically modified compounds as well as by decoupling techniques. The assignments differ in part from those published by Breitmaier & Voelter [2] on FMN and FAD. The solvent dependence of the resonances has been studied in dioxan/water mixtures. The experimental data are compared with published MO calculations and discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19770600208
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  • 4
    Digitale Medien
    Digitale Medien
    Biscalix[4]arene Ligands for Dinuclear Lanthanide Ion Complexation (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2587-2600 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Biscalix[4]arene ; Lanthanide ions ; Energy transfer ; Luminescence ; Dinuclear complexes ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Three types of lower-lower rim linked biscalix[4]arenes that contain carboxylic ester (1) and/or amide functions (2 and 3) at their remaining phenolic oxygen atoms were synthesized. The homo- and heterodinuclear lanthanide ion complexes based on these ligands were used to study the energy transfer between different lanthanide ions. Photophysical studies comparing the luminescence properties of the homodinuclear Eu3+ complex and the heterodinuclear Eu3+-Nd3+ complex of 2 indicated that energy transfer is likely to occur from Eu3+ to Nd3+ with an efficiency of 〉 50%. The luminescence properties turned out to be strongly solvent dependent, which is attributed to structural changes leading to different positions of the lanthanide ions in the cavities provided by the biscalix[4]arene.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719971226
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  • 5
    Digitale Medien
    Digitale Medien
    A Comparative Study of Platinum Di (t-butyl) (15N2)diiminet-Bu-15N=CH—CH=15N-t-Bu (3, 6-15N2)-2, 2, 7, 7-tetramethyl-3, 6-diaza-3, 5-octadiene (95% 15N-enriched). and trans-[(PtCl2(N-ligand)PBu3)] complexes by 195Pt-, 31P- and 15N-NMR (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1174-1182 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 195Pt-, 31P- and 15N-NMR. data are presented for [PtCl2 (t-Bu 15N=CH—CH=15N (t-Bu)) (η2-styrene)] (1), trans-[{PtCl2 (PBu3)}2 (t-Bu 15N=CH—CH=15N (t-Bu))] (2), trans-[PtCl2 (t-Bu 15N=CH—CH=15N (t-Bu)) (PBu3)] (3) and various complexes of the type trans-[PtCl2 (N-ligand) (PBu3)]. In solution the gross structural features of 1 and 2 are shown to be in agreement with those found in the solid state; namely, 1 contains five-coordinate Pt and 2 is dinuclear. In 3 Pt is four-coordinate with only one N-atom of the diimine ligand being coordinated at -50° in CD2Cl2. The NMR. data for 2 and 3 are compared with those of trans-[PtCl2 (N-ligand) (PBu3)] (N-ligand = pyridine, 2, 6-dimethylpyridine, (15N)-hexylamine, (15N)-t-butylamine and (15N)-aniline) and are discussed in terms of the donor and acceptor properties of the N-ligands.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19810640423
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  • 6
    Digitale Medien
    Digitale Medien
    Synthesen von Cholinphosphatiden, VI1) 3-Palmitoyl-glycerin-1-phosphorylcholin (D-α-Lysolecithin) und dessen Unwirksamkeit als Substrat für Acyltransferasen (Lecithin-Synthese) (1970)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 738 (1970), S. 161-169 
    Details
    ISSN: 0075-4617
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Synthesis of Choline Phosphatides, VI1).3-Palmitoyl-glycerol-I-phosphorylcholine (D-α-LySO-lecithin) and its Inactivity as Substrate for AcyltransferasesEnzyme reactions controlling the content of the strong lytic agent lysolecithin (monoacylglycerol-3-phosphorylcholine) in cell membranes, i. e. by degradation or by reacylation, are of great importance for the living cell. Lysolecithins, well defined with respect to configuration and structure, can be used as substrates for studying the metabolic fate of these compounds in membranes. Five of the six theoretically possible isomers of lysolecithin have been prepared by De Haas and Van Deenen (1965). - In this paper the synthesis of the hitherto unknown 3-acyl-glycerol-I-phosphorylcholine (B) is described. 3,4-lsopropylidene-D-mannitol (1) has been benzylated to give 1,2,5,6-tetrabenzyl-3,4-isopropylidene-D-mannitol (2). Acid hydrolysis
    Notizen: Als Modellsubstanzen für biologische Untersuchungen sind einheitliche, konfigurativ eindeutige Lysolecithine von allgemeinem Interesse. Wir beschreiben erstmals die Synthese eines 3-Acyl-glycerin-1-phosphorsäurecholinesters (B) 3.4-Isopropyliden-D-mannit (1) wird zur Tetrabenzyl-Verbindung 2 benzyliert. Saure Hydrolyse von 2 ergibt 1.2.5.6-Tetrabenzy-D-mannit (3), der mittels Bleitetraacetat zu 1.2-Dibenzyl-glycerinaldehyd (4) Gespalten wird. Reduktion von 4 mit Lithiumalant führt zum 1.2-Dibenzyl-glycerin(5), das durch Veresterung mit Palmitinsäurechlorid das 3-Palmitoryl-Dibenzyl 6 liefert. Aus 6 erhält man bei der katalytischen Hydrogenolyse 2-Benzyl-und 1-Benzyl-3-palmitoyl-glycerin (7bzw. ),die chromatographisch getrennt werden . die Phosphorylierung von 7 mittels ß-Brom-äthyl-dichlorphosphat und die nachfolgende Behandlung mit Trimethylamin ergeben 3-Palmitoyl 2-benzyl-glycerin-1-phosphorylcholin (9), das durch katalytische Hydrogenolyse in 3-Palmitoyl-glycerin-1-phosphorylcholin (10) umgewandelt wird. - Das so dargestellte D-αLysolecithin erweist sich im Gegensatz zu 1 -Palmitoyl-glycerin-3-phosphorylcholin (L-α-Lyso-lecithin) nicht als Substrat für Acyl-CoA : Acylglycerinphosphorylcholin-Acyltransferasen,
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.19707380118
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  • 7
    Digitale Medien
    Digitale Medien
    Toxic doses of rac-, (-)-(S)- and (+)-(R)-propranolol in rats and rabbits (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 411-417 
    Details
    ISSN: 0899-0042
    Schlagwort(e): rac-propranolol ; enantiomers ; drug intoxication ; cardiovascular function ; respiratory function ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The contribution of the individual enantiomers ([+]-[R]- and [-]-[S]-propranolol) to rac-propranolol intoxication was studied in anaesthetized, spontaneously breathing (SB) rats and artificially ventilated (AV) rats and rabbits. In the SB rat, propranolol (30 mg.kg-1.h-1 i.v.) decreased heart rate and mean arterial blood pressure and caused hypoventilation, serious hypoxaemia, respiratory acidosis, and death by respiratory arrest. Survival time (ST) in the (+)-(R)-propranolol group (ST 91 ± 5 min) was significantly longer than in the rac-propranolol group (ST 68 ± 6 min). In AV rats and rabbits toxic doses of rac-, (-)-(S)- and (+)-(R)-propranolol, 30 mg.kg-1.h-1 and 15 mg.kg-1.h-1 i.v., respectively, induced comparable effects on haemodynamic variables as in the SB rat. Artificial ventilation lengthened ST by a factor of three to four in rats. In the AV rat, ST's were not significantly different between the rac-, (-)-(S)- and (+)-(R)-propranolol groups. In the rabbit, as in the SB rat, ST in the (+)-(R)-propranolol group was significantly longer than ST's in the rac- and (-)-(S)-propranolol groups. The acute respiratory acidosis in SB rats and the prolonged ST in AV rats suggest that respiratory failure is the primary and cardiovascular failure the secondary cause of death in propranolol intoxication. The potentiation of the toxic effect of the enantiomers observed after dosing the racemate instead of the pure enantiomers could not be explained by a stereoselective difference in plasma propanolol concentration. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    The temperature dependence of steady-state kinetics: What can be learned about pig liver esterase stereospecificity? (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 11-16 
    Details
    ISSN: 0899-0042
    Schlagwort(e): substrate enantioselectivity ; product enantioselectivity ; chirality ; activation enthalpy ; activation entropy ; chiral HPLC ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The steady-state kinetic parameters for pig liver carboxylesterase (PLE)-catalyzed hydrolysis of the prochiral substrate dimethyl phenylmalonate (DMPM) (product enantioselectivity) and the separate enantiomers of three chiral 2-phenylpropionic acid esters (substrate enantioselectivity) were measured at seven temperatures between 288 K and 312 K. Arrhenius plots of turnover numbers against the reciprocal of experimental temperatures yielded enthalpies and entropies of activation at enzyme saturation. (+)-(S)-methyl-2-phenylpropionate, (+)-(S)-4-nitrophenyl 2-phenylpropionate, and both enantiomers of phenyl 2-phenylpropionate showed very similar activation enthalpies and entropies (approximately 50 kJ mol-1 and -50 J mol-1 K-1, respectively), but differences were observed for (-)-(R)-methyl 2-phenylpropionate and (-)-(R)-4-nitrophenyl 2-phenylpropionate. Whereas the entropies of activation of all 2-phenylpropionates were negative, positive entropies of activation were measured in the formation of monomethyl phenylmalonate enantiomers from DMPM. Enthalpy-entropy compensation analysis of the data indicates a common mechanism of PLE substrate and product enantiospecificity in the reactions studied here. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530060105
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  • 9
    Digitale Medien
    Digitale Medien
    Determination of the enantiomers of citalopram, its demethylated and propionic acid metabolites in human plasma by chiral HPLC (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 7 (1995), S. 389-395 
    Details
    ISSN: 0899-0042
    Schlagwort(e): enantioselective HPLC ; depressive patients ; citalopram ; enantioselective metabolism ; human plasma ; racemization ; optical rotation ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A stereoselective HPLC assay has been developed to analyze the enantiomers of citalopram and of its three main metabolites in plasma after their separation on a Chiracel OD column. Using a fluorescence detector, the limit of quantification in plasma samples was 15, 4, 5, and 2 ng/ml for the enantiomers of citalopram (CIT), desmethylcitalopram (DCIT), didesmethylcitalopram (DDCIT), and for the citalopram propionic acid derivative (CIT-PROP), respectively. Except for CIT, all metabolites were derivatized with achiral reagents. Identification of the enantiomers was realized with an optical rotation detector which showed that the enantiomers invert their rotation depending on the polarity and nature of the solvent. Under varying conditions, a racemization study has shown that the pure enantiomers of CIT and its demethylated metabolites are configurationally stable. Preliminary results obtained with five patients treated with CIT show a mean S/R ratio of 0.7 for both CIT and its active metabolite DCIT and of 3.6 for CIT-PROP in plasma. This suggests that the pharmacologically relevant (+)-(S)-isomers of CIT and DCIT could be preferentially and steroselectively metabolized to CIT-PROP. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530070602
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  • 10
    Digitale Medien
    Digitale Medien
    Combined non-enzymatic and enzymatic reduction favors bioactivation of racemic lipoic acid: an advantage of a racemic drug? (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 362-366 
    Details
    ISSN: 0899-0042
    Schlagwort(e): lipoic acid ; reduction ; dihydrolipoamide dehydrogenase ; antioxidant ; enantiomers ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For the antioxidant effect of lipoic acid, reduction to dihydrolipoic acid is considered to be important. Dihydrolipoamide dehydrogenase (LipHD) preferentially reduces R-lipoic acid and in a subsequent reaction, the R-dihydrolipoic acid formed may non-enzymatically reduce S-lipoic acid. Using circular dichroism (CD) spectroscopy, the second order rate constant of the latter reaction was determined (k2 = 15 M-1 sec-1). In vitro, it was found that S-lipoic acid is reduced by LipDH using R-lipoic acid as a catalyst. The non-enzymatic dithiol-disulfide reaction leads to synergistic reduction of the enantiomers which can explain the higher antioxidant activity of racemic lipoic acid found in vivo (Maitra et al. Biochem. Biophys. Res. Commun. 221:422-429, 1996) in comparison to the enantiomers. Lipoic acid is therapeutically active in several diseases via antioxidant activity. These findings suggest that racemic lipoic acid can be therapeutically more active than the separate enantiomers. Chirality 9:362-366, 1997. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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