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  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 3 Ill.
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  • 2
    ISSN: 0947-3440
    Keywords: L-glycero-α-D-manno-Heptopyranosides ; Ethanolamine phosphates ; Phenylacetyl, enzymatic cleavage of ; Carbohydrates ; Glucosylations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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  • 3
    ISSN: 0947-3440
    Keywords: Biscalix[4]arene ; Lanthanide ions ; Energy transfer ; Luminescence ; Dinuclear complexes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 3 Ill.
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 367-379 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 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
    Notes: 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,
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 151-156 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Substituted aminouracils (1) react with malonates by cyclocondensation to 5-hydroxy-pyrido[2,3-d]pyrimidine-2,4,7-triones (2), which give with triethylorthoformate and aniline 6-(phenylaminomethylene)-pyrido[2,3-d]pyrimidine-tetraone (3). Halogenation of 2a-d (with R2 = Me) with phosphorylchloride leads to 5,7-dichloro-pyrido[2,3-d]pyrimidine-2,4-diones (4) by cleavage of the methyl group at N-8, whereas Vilsmeier reaction of 2 affords 5-chloro-6-formyl derivatives (6), which cyclize with arylamines to give benzo[b]pyrimido[4,5-h] 1,6-naphthyridines (9). Compounds 9 were obtained independently by amination of the tosylates 5 to the 5-arylamino compounds 8, and Vilsmeier formylation to yield 9.
    Additional Material: 2 Tab.
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  • 8
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interactions in Crystals. 136. Protonated Dipyridylamine Salts with Different Anions: Monomeric Tetraphenylborate as well as Bis(trifluormethylsulfonate), Dimeric Squarate and Polymeric Chloride DihydrateDi(pyrid-2-yl)amine is monoprotonated by acetic, squaric as well as hydrochloric acid and diprotonated by trifluoromethylsulfonic acid. To explore the anion and hydrogen-bridge dependency of its salts, crystals of the monomeric tetraphenylborate, the dimeric squarate as well as the bis(trifluoromethylsulfonate) and the polymeric chloride hydrate have been grown and their structures determined: Separated by bulky tetraphenylborate anions, pyrid-2-yl(2′-pyridinium) amine cation contains an intramolecular hydrogen bridge N⊕H…N and is slightly folded. The squarate salt dimer exhibits additional bridges, N—H…O⊖ and O—H…O. The severely twisted di(2-pyridinium)amine dication is connected to its trifluormethylsulfonate counter anions by altogether three H-bridges, two N⊕H…O and one N—H…O. The chloride dihydrate crystallizes in layers of 16-membered rings, formed from three Cl anions and five water molecules. The diversity of the hydrogen-bridge dominated salt structures is discussed based on comparison with selected literature examples and on PM3 calculations.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 523-531 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrathiafulvalenes. XXVIII. Diastereoselective Formation of Unsymmetrically Substituted TetrathiafulvalenesAs a part of our work on chemistry of tetrathiafulvalenes, we make a contribution to elucidate the mechanism of forming tetrathiafulvalenes starting from 1,3-dithiole derivatives. We describe the synthesis of unsymmetrically substituted tetrathiafulvalenes (8a-i) starting with the 2H-1,3-dithiolium salt (7a-i)/tert. amine, 2-ethylthio-1,3-dithiolium salt (5a-i)/triphenylphosphine or 1,3-dithiole-2-thione (4a-i)/triethyl phosphite. If the 1,3-dithiole derivatives are substituted by bulky groups the isolation of the cis- and trans-isomers was possible due to differences in the solubility. In these cases (8c-i) the predominant formation of the cis-isomer is observed in the reaction of 2-ethylthio-1,3-dithiolium salts (5c-i) with triphenylphosphine or 1,3-dithiole-2-thiones (4c-i) with triethyl phosphite. This result is in agreement with the formation of an intermediate, analogously to the Wittig reaction. In the reaction of 2H-1,3-dithiolium salts (7a-i) with tertiary amines the relation of isolated cis- and trans-isomers is not 1:1 and depends on the bulkiness of the tertiary amine. These observations exclude in these three reactions a carbene mechanism for the dimerization of the 1,3-dithiole units to tetrathiafulvalenes.
    Additional Material: 5 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 351-357 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Compounds containing N-acetyl-D-muramic acid and (L-1-aminoethyl)phosphonic acid were designed as potential inhibitors of the D-glutamic acid-adding enzyme of the biosynthesis of bacterial peptidoglycan. 2-Acetamido-2-deoxy-3-O-[(R)-2-propionyl-(L-1-aminoethyl)phosphonic acid]-D-glucopyranose (3) was synthesized. 2-Acetamido-1,4,6-tri-O-acetyl-2-deoxy-3-O[(R)-2-propionyl-(L-1-aminoethyl)phosphonic acid dimethyl ester]-α,β-D-glucopyranose (9) was also prepared and was submitted to the MacDonald reaction in order to introduce a phosphate group on the anomeric position. A complex mixture of phosphorylated or/and methylated derivatives of 3 was obtained. They were purified by h.p.l.c. and characterized by analyses of hexosamine, amino acid and labile phosphate, and by plasma desorption mass spectrometry. Neither 3 nor its derivatives inhibited the D-glutamic acid-adding enzyme from Escherichia coli.
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