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  • Organic Chemistry  (6,591)
  • 1980-1984  (3,406)
  • 1945-1949  (1,551)
  • 1925-1929  (1,634)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 616-624 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structural modifications of multifidene (1), viridiene (2) and ectocarpene (5) led to the synthesis of eleven new pheromone components or imitatin substances mostly by Grignard alkylation of cyclopentene and cycloheptadiene synthons. A new lactone α,ω dienol conversion is reported.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 640-653 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(Ia) photoelectron (PE) spectra of the (E,E)-, (E,Z)- and (Z,Z)-isomers of the title compound have been recorded to obtain information about their conformation in the gas phase. For a valid correlation with the PE data of other dienes it is necessary to take the potentials V(ϕ) for internal rotation and the corresponding conformer population densities P (ϕ) into account, as well as the rather complicated way wy in which the π-1 ionization energy gap ΔI(ϕ) depends on the direct π-orbital interaction and the long-range ‘through-space’ interaction between the semi-localized methyl-group orbitals and the π-orbitals. These factors being taken into account, the mean twist angles, ϕ, compatible with the PE-spectroscopic results are ϕ (E,E) ≍ O° ± 30°, ϕ (E,Z) ≍ 80° or 110° within ± 15°, and ϕ (Z,Z) ≍ 85° to 105°. These results are in rough agreement with electron diffraction data by Traetteberg [15], other spectroscopic results and, for the (E, E)- and (Z,Z)-isomers, internal rotation potentials V(ϕ) previously calculated by Roth [17]. On the other hand the potential V (ϕ) proposed for the (E,Z)-isomer does not seem to be compatible with our findings.
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The olefins 2, 7, 11, and 19, have been reduced using catalytic amounts of cob(I)alamin(I(I)). During a slow saturation, the catalyst is able to differentiate the two diastereotopic faces of the endocyclic double bonds in 11 (t1/2 4 h,. cf. Scheme 3) are reduced much faster. A rationalization of the data can be obtained formulating tertiary alkylcobalamins as intermediates. Of the oxime 6 (cf. Scheme 2) and the p- bromobenzoate 23 (cf. Scheme 5) the structures have been determined by X-ray analysis.
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structural Elucidation of Niphimycin, Part 3. Identity of Scopafungin and Niphimycin I. Position of the Malonyl Residue of Niphimycin and CopiamycinThe identity of scopafungin with niphimycin I was proven by spectroscopic and chromatographic methods and by common degradation products. The position of the malonyl residue in niphimycin I (9) and in copiamycin (14) was deduced by 1H-NMR spin-decoupling experiments of a degradation product (10).
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, Chemical and Electrical Properties of Tetrathiafulvalene with a 1,6-Methano[10]annulene Moiety and of Chalcogendiimide-DerivativesThe synthesis of the tetrathiafulvalene 6 has been described: the reaction of 1 with the benzenedithoil 2 yielded the bis-dithioacetal 3 of 1,6-methano[10]annulene-dicarbaldehyde 1. The oxidation of 3 in the presence of HBF4 in Et2O yielded the salt 4, elimination of a hydride anion with triphenylmethylium tetrafluoroborate the salt 5, and elimination of a proton in 5 with Et3N the tetrathiafulvalene 6 with a 1,6-methano[10]annulene moiety. The spectroscopic and electrochemical properties of 6 are described, and also the syntheses and properties of charge-trasnfer complexes 7 and 8, including the properties of electric conductivity of 7 and 8. the syntheses of 9-13 are reported and also their spectroscopic properties.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 765-769 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Voltammetric Investigations on the Oxidation Step of Symmetrical Triazacarbocyanine Dyes in Acetonitrile SolutionThe oxidation behaviour of twelve symmetrical triazacarbocyanine dyes with different heterocycles in MeCN (containing tetrabutylammonium perchlorate) has been investigated by means of dc-, ac- and cyclic triangular wave voltammetry. The oxidation mechanism has been found to be of the type ec, with the electrochemical step being reversible to irreversible. Oxidation potentials and transfer coefficients have been measured (E1/2 1.60 to 2.12 V vs. Ag/AgCl) and compared with known properties of carbocyanines. The effect of substituents X has been studied on the compounds 1,3-diethyl-2-[3-(1,3-diethyl-5-X-benzimidazolin-2-ylidene)-1-triazeno]-5-X-benzimidazolium tetrafluoroborate ((1a(X)) and 3-ethyl-2-[3-ethyl-5-X-Δ4-1,3-thiazolin-2-ylidene)-1-triazeno]-5-X-1,3-thiazolium tetrafluoroborate (1g(X)), and ρ-values of 0.425 and 0.565 V, respectively, have been found.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 947-952 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathine 8 and 9 form (E)-2-hezen-1-ol (1) as common starting material is described. The two enantiomeric forms exhibit different organoleptic properties.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1003-1011 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plectranthons A, B, C, and D. Diterpenoid Phenanthrene-1,4-diones from Leaf-glands a Plectranthus sp. (Labiatae)The following structures of four new 1,4-phenanthraquionones, isolated in minute amounts from the coloured leaf-glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3-hydroxy-5, 7,8-trimethyl-2-(2-propenyl)phenanthrene-1, 4-dione), plectranthon B (2; 2-(2ξ-acetoxypropyl)-3-hydroxy-5,7,8-trimethylphenanthrene-1,4-dione), plextranthon C (3; 3-hydroxy- 7,8-diemethyl-2-(2-propenyl)phenanthrene-1,4-dione), and plectranthon D (4; 3-hydroxy-7,8,10-trimethyl-2-(2-propenyl)phenanthrene-1,4-dione). 2-(2ξ-Hydroxypropyl)-3,6-dihydroxy-5,7,8-trimethylphenanthrene-1,4-dione (11), a compound very similar to 1-4, was prepared by a Wagner-Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20-phenanthrenes of diterpenoid origin.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 535-556 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclitol Reactions, VIII. - Synthesis of Enantiomerically Pure (+)-Lycoricidine from D-GlucoseThe synthesis of enantiomerically pure (+)-lycoricidine (1) from D-glucose is described. The key reaction step is the addition of the aromatic anion 31 to the nitroolefin sugar 18 which gives the branched-chain sugars 32 and 33. After liberation of the aldehyde function of 32 and intramolecular aldol addition, 32 yields the lacton 35, a branched-chain nitroinositol with muco configuration. Reduction of the nitro group yields the amine 38 and rearrangement the lactam 40. Selective benzoylation to 43 followed by dehydration gives 47 which allows deblocking to (+)-lycoricidine (1). (+)-Lycoricidine (1) and its triacetate 49 are identical with the natural product.
    Notes: Die Synthese von enantiomerenreinem (+)-Lycoricidin (1) aus D-Glucose wird beschrieben. Der Schlüsselschritt der Reaktionsfolge ist die Addition des aromatischen Anions 31 an den Nitroolefin-Zucker 18, der zu den verzweigten Nitrozuckern 32 und 33 führt. Durch intramolekulare Aldolreaktion ist nach Freisetzung der Aldehydgruppe in 32 über 34 das Lacton 35 erhältlich, das einen verzweigten Nitroinosit der muco-Konfiguration enthält. Die Reduktion der Nitrogruppe in 35 führt zur Aminoverbindung 38, deren Lactongruppierung in das Lactam 40 umgelagert werden kann. Das aus 40 durch selektive Benzoylierung erhältliche Tribenzoat 43 ergibt durch Eliminierung von Wasser das Derivat 47, aus dem freies (+)-Lycoricidin (1) gewonnen werden kann. (+)-Lycoricidin (1) und dessen Triacetat 49 sind mit dem Naturprodukt identisch.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 575-584 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminonucleosides, XI. - Bis(trimethy ammonio) Derivatives of AdenosineA five-step reaction starting from the aminonucleosides 1a or 1b yields the bis(trimethylammonio) derivatives 3′-trimethylammonio-6-[3-(trimethylammonio)propylamino]-3′-deoxyadenosine (8a) and 5′-trimethylammonio-6-[2-(trimethylammonio)ethylamino]-5′-deoxyadenosine (8b), respectively. The new compounds are biologically active and have muscle relaxing properties.
    Notes: Ausgehend von den Aminonucleosiden 1a und 1b wird in einer Fünf-Stufen-Reaktion die Synthese der Bis(trimethylammonio)-Derivate 3′-Trimethylammonio-6-[-3-(trimethylammonio)propylamino]-3′-desoxyadenosin (8a) und 5′-Trimethylammonio-6-[2-(trimethylammonio)ethylamino]-5′-desoxy-adenosin (8b) beschrieben. Die neuen Verbindungen sind biologisch aktiv und besitzen muskel-relaxierende Eigenschaften.
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  • 11
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Acylaminobromomalonates and Acylaminobromoacetates with Trialkylphosphites - A Simple Synthesis of Ethyl 2-Amino-2-(diethoxyphosphoryl)acetateDepending on the reaction conditions acylaminobromomalonates 1 and trialkylphosphites yield either 5-alkoxyoxazoles 7, 2-[acyl(dialkoxyphosphoryl)amino]malonates 8, or 2-acylamino-2-(dialkoxyphosphoryl)malonates 2. N-Acylglycin esters 9 can be converted into the corresponding α-bromo derivatives 10 by treatment with bromine or N-bromosuccinimide. Treatment of 10 with trialkylphosphites yields 2-acylamino-2-(dialkoxyphosphoryl)acetates 12. Removal of the protecting groups from the Boc or trichloroethoxycarbonyl derivatives 12g and 12h, respectively, leads to ethyl 2-amino-2-(diethoxyphosphoryl)acetate (11). Reaction of 10a with triphenylphosphane yields the phosphonium salt 14a which is converted into the 2,3-bis(benzoylamino)fumarate 18 by action of base.
    Notes: In Abhängigkeit von den Reaktionsbedingungen liefern Acylaminobrommalonester 1 mit Trialkylphosphiten entweder 5-Alkoxyoxazole 7, 2-[Acyl(dialkoxyphosphoryl)amino]malonester 8 oder 2-Acylamino-2-(dialkoxyphosphoryl)malonester 2. N-Acylglycinester 9 können mit Brom oder N-Bromsuccinimid in die α-Bromderivate 10 übergeführt werden, die mit Trialkylphosphiten glatt die 2-Acylamino-2-(dialkoxyphosphoryl)essigester 12 ergeben. Durch Entfernen der Schutzgruppen aus den Boc- und Trichlorethoxycarbonyl-Derivaten 12g und 12h ist 2-Amino-2-(diethoxyphosphoryl)essigsäure-ethylester (11) zugänglich. Das durch Umsetzung von 10a mit Triphenylphosphan erhältliche Phosphoniumsalz 14a erleidet bei Baseneinwirkung eine Dimerisierung zum 2,3-(Bisbenzoylamino)fumarat 18.
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  • 12
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XXXVI.  -  Investigation of Reactivity in Tri- and Pentasaccharide Syntheses. Improved Synthesis of the Pentasaccharide Chain of the Forssman AntigenThe dependence of selectivity and yield upon the initial saccharide′s reactivity is shown for the syntheses of the trisaccharides 7, 8, 9, and 12. From 8 comes the trisaccharide halide 15 which, together with 22 in a block synthesis, yields the pentasaccharide 23 which in turn, after deprotection, gives the pentasaccharide chain of the Forssman hapten 25. This improved synthesis of 25 only uses 2-azido sugars and avoids the use of 2-phthalimido sugars.
    Notes: Die Abhängigkeit der Selektivität und der Ausbeute von den Reaktivitäten der Ausgangssaccharide bei der Synthese der Trisaccharide 7, 8, 9 und 12 wird gezeigt. Aus 8 ist der Trisaccharidhalogenid-Baustein 15 darstellbar, der in einer Blocksynthese mit 22 das Pentasaccharid 23 liefert, dessen Entblockierung zur Pentasaccharidkette des Forssman-Haptens 25 führt. Diese verbesserte Synthese von 25 verwendet nur 2-Azido-Zucker und vermeidet 2-Phthalimido-Zucker.
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  • 13
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry at Rigid Surfaces, 6.  -  Photochemically Induced Reactions with Surface-bound SensitizersAerosil® reacts with 3-triethoxysilylpropylamine to give Aminoaerosil(1) which can be converted into aerosils2a-f by means of sensitizers containing carboxyl groups. The density of the functional groups on the surface which was determined by several methods clearly effects the reaction. On irradiation in 2-propanol, acetone was produced as well as the surface-bound pinacol, e. g.4, which could be reoxidized by lead tetraacetate to give2b. Hydrodimerization on the surface of2b
    Notes: Aerosil® wird mit 3-Triethoxysilylpropylamin zu Aminoaerosil(1) umgesetzt und dieses mit carboxylgruppenhaltigen Sensibilisatoren in die grenzflächenmodifizierten Aerosile2a-f übergeführt. Die Beladungsdichte mit funktionellen Gruppen, die nach unterschiedlichen Methoden bestimmt wird, beeinflußt maβgebend das Reaktionsergebnis. Bei der Bestrahlung der grenzflächenmodifizierten Aerosile2a - c in Isopropylalkohol entstehen Aceton sowie das grenzflächengebundene Pinakol, z. B.4, das mit Bleitetraacetat wieder zu2b rückoxidiert werden kann. Die Hydrodimerisierung an der Grenzfläche von2b läuft 3mal langsamer als mit der Analogverbindung im Homogensystem. Bei der Photoreduktion von2b geringer Beladungsdichte entstehen neben dem Pinakol4 das grenzflächenfixierte Carbinol8 sowie das gemischte Pinakol9. An Aerosil grenzflächengebundene p-Acetylbenzoesäure (modifiziertes Aerosil2b) wird  -  in Analogie zu früher im Homogensystem durchgeführten Versuchen  -  in (S)-Milchsäure-(p-menth-3-ylester) und (R, S)-Milchsäure-(p-menth-3-ylester) bestrahlt. In beiden Fällen bildet sich grenzflächengebundenes Pinakol4, im zweiten Fall auch eine geringe Menge an optisch aktivem Lactat. Mit grenzflächengebundenen Sensibilisatoren werden folgende photochemisch induzierte Reaktionen studiert: a) die photosensibilisierte Addition von Isopropylalkohol an Maleinsäure und Maleinsäure-diethylester zu Terebinsäure(12a) bzw. deren Ethylester; b) die sensibilisierte cis/trans-Isomerisierung von Maleinsäure- bzw. Fumarsäure-diethylester; c) die sensibilisierte cis/trans-Isomerisierung von 1,2-Diphenylcyclopropan; d) die sensibilisierte Autoxidation von 2,5-Dimethylfuran. Bei allen vier Reaktionstypen entstehen  -  wenn auch langsamer  -  die gleichen Reaktionsprodukte wie mit analog strukturierten Sensibilisatoren im Homogensystem. Bei den Reaktionen b), c) und d) wurden der Wirkungsfaktor WF (Quotient der Reaktionsgeschwindigkeiten im Homogen- und Heterogensystem) sowie die Wiederverwendbarkeit SF (Quotient der Umsätze nach gleichen Zeiten im Zweit- und Erstversuch) der heterogen gebundenen Sensibilisatoren bestimmt.
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  • 14
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Peroxides, XXV. - The Reactivity of Benzylic Methyl Groups at the Barton Type Cyclization of Organic HydroperoxidesOn the earlier reported cyclization conditions [lead(IV) acetate, n-pentane, cyclization apparatus] the hydroperoxides 1a-d yield the 2,3-dioxabenzocyclooctenes 3a, 3b and 2,3-dioxabenzocyclononenes 3c, 3d as well as the 1,2-dioxolanes 4a, 4b and 1,2-dioxanes 4c, 4d, respectively. Starting from the hydroperoxide 2 the 1,2-dioxolane 7 is the only cyclic peroxide obtained. The symmetric and the unsymmetric dialkyl peroxides 5, 6, 8, and 9 are obtained in all cases. - On the reaction of the hydroperoxides 1a, 1c, and 1d in acetic acid the cyclization is reduced to a very small extent. the symmetric dialkyl peroxides 5a, 5c, and 5d and the alkyl methyl peroxides 10a, 10c, and 10d are obtained in low yields. - The relatively high yields of the peroxides 3 are discussed on the basis of stereo-electronic effects.
    Notes: Unter den früher angegebenen Cyclisierungsbedingungen [Blei(IV)-acetat, n-Pentan, Cyclisierungsapparatur] ergeben die Hydroperoxide 1a - d die 2,3-Dioxobenzocyclooctene 3a, 3b und 2,3-Dioxabenzocyclononene 3c, 3d sowie die 1,2-Dioxotane 4a, 4b und 1,2-Dioxane 4c, 4d. Das Hydroperoxid 2 ergibt als cyclisches Peroxid ausschließlich das 1,2-Dioxolan 7. Daneben werden symmetrische sowie unsymmetrische Dialkylperoxide (5, 6, 8, 9) erhalten. - Bei der Reaktion der Hydroperoxide 1a, 1c und 1d in Essigsäure wird die Cyclisierung fast vollständig zurückgedrängt; in geringen Mengen werden die symmetrischen Dialkylperoxide (5a, 5c, 5d) sowie auch (Alkyl)(methyl)peroxide (10a, 10c, 10d) nachgewiesen bzw. isoliert. - Die relativ hohen Ausbeuten an den Peroxiden 3 werden diskutiert und durch stereo-elektronische Effekte erklärt.
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  • 15
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep, Reversible Redox Systems, XXXIII. - Reversible Transformation of a [4]Radialene into a Cyclobutadiene by Electron Transfer in Four StepsTetrapyridylcyclobutane 1 forms with chloroformate after deprotonation the red [4]radialene derivative 2aREDc which is oxidized by AgBF4 to the blue “squaric acid” derivative 2aOXc ≡ REDa, possessing cyanine type structure. The radialene 2aREDc constitutes the lowest oxidation level of a four-step, reversible redox system which allows for the first time to carry out electrochemically the reversible transformation [4]radialene ⇄ cyclobutadiene (here: 2aOXa). The redox properties of the system 2a (〉N-CO2Et) are compared with that of 2b (〉N-Me). The influence of the pyridinium substituents on the redox potentials is estimated by comparison with the model compounds 5a and 5b. From the conversion 2aSEMa → 2aOXa + e an antiaromatization energy of ca. 12 kcal/mol = 50 kJ/mol is derived. This value and the method employed is compared with those in the literature. Finally, the redox properties of the related [4]radialenes 2a, 2b, 9, and 10 are discussed, covering a 3.50 V range of potentials.
    Notes: Aus Tetrapyridylcyclobutan 1 und Chlorameisensäureester entsteht unter Deprotonierung das rote [4]Radialenderivat 2aREDc, das sich mit AgBF4, zum blauen, cyaninartigen “Quadratsäure”. Derivat 2aOXc ≡ REDa oxidieren läßt. 2aREDc ist das Endglied eines vierstufigen, reversiblen Redoxsystems, mit dem erstmals die Umwandlung [4]Radialen ⇄ Cyclobutadien (hier 2aOXa) elektrochemisch möglich ist. Das Redoxverhalten des Systems 2a (〉N-CO2Et) wird mit dem von 2b (〉N-Me) verglichen. Durch Abschätzung des Einflusses der Pyridinium-Substituenten auf die Potentiallage anhand der Modelle 5a und 5b wird aus dem Übergang 2aSEMa → 2aOXa + e die Antiaromatisierungsenergie dieses Cyclobutadiens zu ca. 12 kcal/mol = 50 kJ/mol abgeschätzt. Dieser Wert und die angewandte Methode werden mit Literaturergebnissen verglichen. Schließlich wird das Redoxverhalten der verwandten Radialene 2a, 2b, 9 und 10 diskutiert, das einen Potentialbereich von 3.50 V umfaßt.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 687-694 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conjugation in Macrocyclic Systems, XXXI. - Isomeric Naphtho[14]annulenes with 1,2- and 2,3-AnnellationFor the syntheses of naphtho[1,2-α][14]annulene (1) and naphtho[2,3-α][14]annulene (2) the 1,2- and 2,3-di(1-hexen-5-ynyl)naphthalenes 4 and 8, respectively, were prepared. Cyclisation of 4 and 8 by oxidative coupling yielded 5 and 9, respectively, the prototropic isomerisation of which led to 1 and 2, respectively. - On the basis of 1H NMR spectra structure 1B was assigned to 1 whereas the different annellation type 2A was proven for 2. 1B shows fairly strong diatropicity in the [14]annulene system; no evidence for diatropicity was found, however, for the 2,3-annellated isomer 2A.
    Notes: Zur Synthese von Naphtho[1,2-α][14]annulen (1) und Naphtho[2,3-α][14]annulene (2) wurden die 1,2- und 2,3-Di(1-hexen-5-inyl)naphthaline 4 und 8 dargestellt. Cyclisierung von 4 und 8 durch oxidative Kupplung ergab 5 bzw. 9, deren prototrope Isomerisierung zu 1 bzw. 2 dagegen die symmetrische Struktur 2A. 1B zeigt mäßig starke Diatropie im [14]Annulen-System, während für 2A keine Diatropie nachzuweisen ist.
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  • 17
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Trialkylsilyl Trifluoromethanesulfonates, II. - Synthesis of O-Alkyl-O-(trialkylsily1)ketene Acetals and 2-(Trialkylsilyl)carboxylatesAlkyl carboxylates 2 are silylated by trialkylsilyl triflates 1 in the presence of triethylamine (3) to yield ketene acetals 4. In reactions of the esters 6 mixtures of ketene acetals 7 and at the α-carbon silylated esters 8 are obtained. Ethanoic acid esters and lactones are doubly silylated to give the products 11, 12, and 15, respectively. Under suitable conditions silylation of the esters 10 gives rise to the 2-trimethylsilylethanoic acid esters 13. The thermodynamically more stable products are obtained. Product distributions depend on the structure of the esters and the silylating agents 1.
    Notes: Durch Silylierung mit Trialkylsilyltriflaten 1 in Gegenwart von Triethylamin (3) erhält man aus Carbonsäureestern 2 die Ketenacetale 4, die Ester 6 ergeben Gemische aus Ketenacetalen 7 und am α-Kohlenstoffatom silylierten Estern 8. Ethansäureester 10 und Lactone 14 werden durch 1/3 zweifach zu den Produkten 11, 12 bzw. 15 silyliert. Unter geeigneten Bedingungen können 2-(Trimethylsilyl)ethansäureester 13 aus den Estern 10 gewonnen werden. Es resultieren die thermodynamisch stabilen Produkte. Die Abhängigkeit der Produktverteilung von der Struktur der Reaktionspartner wird diskutiert.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1015-1017 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Simple Synthesis of TetramethyloxamideTetramethyloxamide has been prepared by a new and simple procedure from dimethylformamide, iron(II) sulfate heptahydrate, and tert-butyl hydroperoxide (yield 43%) or 30% aqueous hydroperoxide (yield 77%).
    Notes: Es wird eine neue, einfache Synthese von Tetramethyloxamid aus Dimethylformamid, Eisen(II)-sulfat-heptahydrat und tert-Butylhydroperoxid (Ausb. 43%) oder 30proz. Wasserstoffperoxid (Ausb. 77%) beschrieben.
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1025-1034 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Thermal and Photochemical Reactions of New Mesoionic 1,3,2-OxathiazolonesThe synthesis and spectroscopic data of the new mesoionic 1,3,2-oxathiazolones 3b, c, e are described. As cyclic thiocarbonyl imine, 3e reacts with dimethyl acetylenedicarboxylate at 80°C with evolution of carbon dioxide to produce the 5-arylisothiazole derivative 6e (80%). On the other hand, the visible light-induced fragmentation of 3e leads to a nitrile sulfide intermediate of type 10 which suffers unimolecular decay with formation of sulfur and the arylnitrile 11e or which can be partially trapped with dimethyl acetylenedicarboxylate to form the isomeric 3-arylisothiazole derivative 13e (29-21%). The analogous photochemical decay of 3c in the presence of dimethyl acetylenedicarboxylate proceeds with formation of the isothiazole derivative 13c besides sulfur and the nitrile 11c, whereas the nitrile sulfide 10b  -  photochemically generated from 3b  -  does not more react with formation of an isothiazole derivative.
    Notes: Die Synthese und spektroskopischen Daten der neuen mesoionischen 1,3,2-Oxathiazolone 3b, c, e werden beschrieben. Als cyclisches Thiocarbonylimin reagiert 3e mit Acetylendicarbonsäuredimethylester bei 80°C unter Kohlendioxid-Freisetzung zum 5-Arylisothiazol-Derivat 6e (Ausb. 80%). Demgegenüber führt die mit sichtbarem Licht induzierte Fragmentierung von 3e zu einer Nitrilsulfid-Zwischenstufe vom Typ 10, die unimolekularen Eigenzerfall in Schwefel und das Arylnitril 11e erleidet oder mit Acetylendicarbonsäure-dimethylester teilweise als isomerer 3-Aryl-isothiazol-Abkömmling 13e (Ausb. 29-21%) abgefangen werden kann. Der analoge photochemische Zerfall von 3c liefert in Gegenwart von Acetylendicarbonsäure-dimethylester neben Schwefel und dem Nitril 11c das Isothiazol-Derivat 13c, während das aus 3b photochemisch entstandene Nitrilsulfid 10b nicht mehr zur Isothiazol-Bildung befähigt ist.
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  • 20
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure and Reactions of 2,2′-Oxybis[2,2-dimethyl-4,4,5,5-tetrakis(trifluoromethyl)-1,3,2λ5-dioxaphospholane]The structure of the title compound 3 has been determined by X-ray diffraction. 3 was found to crystallize in the monoclinic system (space group P21/c). Two crystallographically independent molecules are observed in the crystal lattice which differ with regard to the P - O - P angle [147.3(3)° and 150.8(3)°, respectively]. Formation of 3 has been observed in the reaction of the chlorophosphorane Me2P(pfp)Cl (2; pfp = perfluoropinacolyl) with NaHCO3, and of the siloxyphosphorane Me2P(pfp)OSiMe3 (1) with Me2P(= O)Cl. Cleavage of 3 with methanol furnishes the previously known compound Me2P(pfp)OMe (5) and the acyclic phosphinic acid ester Me2P(= O)OC(CF3)2C(CF3)2OH (4b). Reaction of 3 with water leads to exclusive formation of 4b; the isomeric hydroxyphosphorane Me2P(pfp)OH (4a) has not been observed.
    Notes: Die Struktur der monoklin (Raumgruppe P21/c) kristallisierenden Titelverbindung 3 wurde durch Röntgenstrukturanalyse bestimmt (Abb. 1-3). Im Kristallgitter werden zwei kristallographisch unabhängige Moleküle beobachtet, die sich in der Groβe des P - O - P-Winkels unterscheiden [147.3(3)° bzw. 150.8(3)°]. 3 bildet sich bei der Umsetzung des Chlorphosphorans Me2P(pfp)Cl (2; pfp = perfluorpinakolyl) mit NaHCO3 sowie aus dem Siloxyphosphoran Me2P(pfp)OSiMe3 (1) mit Me2P(= O)Cl. Die Spaltung von 3 mit Methanol liefert die bereits bekannte Verbindung Me2P(pfp)OMe (5) und den acyclischen Phosphinsäureester Me2P(= O)OC(CF3)2C(CF3)2OH (4b). Die Umsetzung von 3 mit H2O führt ausschließlich zu 4b; die Bildung des isomeren Hydroxyphosphorans Me2P(pfp)OH (4a) wird nicht beobachtet.
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  • 21
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Electron Donor-Acceptor Compounds, XXVII.  -  Quinhydrones of the [4.4]Paracyclophane SeriesIn the context of the determination of the distance and orientation dependence of charge-transfer interactions the diastereomeric quinhydrones 5 and 6 of the [4.4]paracyclophane series were prepared. Cyclisation of 1,4-bis(3-bromopropyl)-2,5-dimethoxybenzene with 2,5-dimethoxy-1,4-benzenedimethanethiol yielded the diastereomeric dithia[5.5]paracyclophanes 9/10 which, via the corresponding disulfones 11/12, were converted into the 6,9,16,19-tetramethoxy-[4.4]paracyclophanes 7/8. The stereoisomers 7/8, as well as the pairs of diastereomers 9/10 and 11/12. have been separated; experiments on thermal isomerisation are reported. The assignment of 7/8 to the pseudoortho and pseudogeminal constitution was established by an X-ray structure analysis of 7 the molecular structure of which is discussed. Oxidative demethylation of 7 and 8 yielded the diastereomeric quinhydrones 5 and 6. Charge-transfer absorptions of these compounds are compared with those of the corresponding [3.3]paracyclophane quinhydrones 3b and 4b and are discussed under the aspect of the specific conformational situation present in the [4.4]paracyclophane system.
    Notes: Zur Untersuchung der Abstands- und Orientierungsabhängigkeit der Charge-Transfer-Wechsel-wirkungen wurden die diastereomeren Chinhydrone 5 und 6 der [4.4]Paracyclophan-Rehe synthetisiert. Die Cyclisierung von 1,4-Bis(3-brompropyl)-2,5-dimethoxybenzol mit 2,5-Dimethoxy-1,4-benzoldimethanthiol ergab die diastereomeren Dithia[5.5]paracyclophane 9/10, die über die entsprechenden Disulfone 11/12 in die 6,9,16,19-Tetramethoxy[4.4]paracyclophane 7/8 über-führt wurden. Ebenso wie die Diastereomeren-Paare 9/10 und 11/12 lieβen sich auch 7/8 in die Stereoisomeren trennen; über Isomerisierungsversuche wird berichtet. Die Zuordnung von 7/8 zur pseudoortho- und pseudogeminalen Reihe geschah durch Röntgen-Strukturanalyse von 7, für das die Molekülstruktur diskutiert wird. Oxidative Demethylierung von 7 und 8 diastereomeren Chinhydrone 5 und 6. Die Charge-Transfer-Absorptionen dieser Verbindungen werden mit denen der entsprechenden [3.3]Paracyclophan-Chinhydrone 3b und 4b verglichen und unter dem Gesichtspunkt der im [4.4]Paracyclophan-System vorliegenden besonderen Konformationsverhältnisse diskutiert.
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  • 22
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1065-1072 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Electron Donor-Acceptor Compounds, XXVIII.  -  Synthesis and Charge-Transfer Properties of 4,7-Diaza[2.2]paracyclophanes
    Notes: 2,5-Bis(brommethyl)pyrazin (3) wurde dargestellt und mit 1,4-Benzoldimethanthiol und 2,5-Dimethoxy-1,4-benzoldimethanthiol zu den entsprechenden 5,8-Diaza-2,11-dithia[3.3]paracyclophanen cyclisiert. Photochemische Schwefel-Extrusion ergab 4,7-Diaza[2.2]paracyclophan (1) und die stereoisomeren 12,15-Dimethoxy-4,7-diaza[2.2]paracyclophane 5 und 6, die chromatographisch getrennt wurden.  -  Absorptions- und Emissionsspektren von 5 und 6 beweisen die π-Acceptor-Eigenschaft eines Pyrazins, das im [2.2]Paracyclophan-System einem starken Elektron-Donor gegenübersteht. Die beobachtete Lösungsmittelabhängigkeit der Charge-Transfer-Absorptionen von 5 und 6 (Abb.) wird auf eine Änderung der Elektronenaffinität des Pyrazin-Teils durch Solvatation und Protonierung zurückgeführt. Der Vergleich von Charge-Transfer-Eigenschaften der Stereoisomeren 5 und 6 zeigt die Orientierungsabhängigkeit der Donor-Acceptor-Wechselwirkung.2,5-Bis(bromomethyl)pyrazine (3) was prepared and cyclized with 1,4-benzenedimethanethiol and 2,5-dimethoxy-1,4-benzenedimethanethiol to give the corresponding 5,8-diaza-2,11-dithia[3.3]-paracyclophanes. Photochemical sulfur extrusion yielded 4,7-diaza[2.2]paracyclophane (1) and the stereoisomeric 12,15-dimethoxy-4,7-diaza[2.2]paracyclophanes 5 and 6 which were separated by chromatography.  -  Absorption and emission spectra of 5 and 6 demonstrate the π-acceptor quality of pyrazine when linked in a [2.2]paracyclophane system vis-a-vis to a strong electron donor. The solvent dependence of charge-transfer absorptions observed for 5 and 6 (Fig.) is ascribed to the change in electron affinity of the pyrazine moiety by solvation and protonation. By comparing charge-transfer properties of the stereoisomers 5 and 6 the orientation dependence of electron donor-acceptor interactions is shown.
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  • 23
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1020-1030 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Naphthoquinones, VII. - Synthesis of Rotundiquinone and 2,3′-Bijuglone via Halogenated BinaphthyldiquinonesAn improved synthesis of the unsymmetric quinoid-quinoid cross-linked [2,3′-binaphthyl]diquinones rotundiquinone (3a) and 2,3′-bijuglone (3c) was achieved by demethylation followed by hydrogenolytic dehalogenation starting from the monobromo derivatives 14a and 14c. Synthesis and properties of some more halogenated bijuglones are described.
    Notes: Eine verbesserte Synthese der unsymmetrisch über die chinoiden Ringe verknüpften [2,3′-Binaphthyl]dichinone Rotundichinon (3a) und 2,3′-Bijuglon (3c) geht von den leicht zugänglichen Monobromderivaten 14a und 14c aus, die sich glatt entmethylieren und anschließend hydrogenolytisch enthalogenieren lassen. Synthesen und Eigenschaften weiterer halogenierter Bijuglone werden beschrieben.
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  • 24
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1043-1046 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Attempts on N-Amination of AlkaloidsSpiro[cyclohexane-1,3′-oxaziridine] (1) and ephedrine (4) react with N-N-bond formation to give the cyclic hydrazine derivative 6. Compound 1 also reacts with the hydroxytetrahydropapaverine 9a with N-N-bond formation; the reaction product undergoes C-C-cleavage under the action of acid and forms the hydrazonium salt 10.
    Notes: Spiro[cyclohexan-1,3′-oxaziridin] (1) reagiert mit Ephedrin (4) unter N-N-Knüpfung zu dem cyclischen Hydrazinderivat 6. Das Hydroxytetrahydropapaverin 9a reagiert mit 1 ebenfalls glatt unter N-N-Knüpfung; das Reaktionsprodukt erleidet durch Säure unter C-C-Spaltung Umlagerung zum Hydrazoniumsalz 10.
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  • 25
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1047-1072 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XLVII. - Synthesis of Tri- and Tetrasaccharide Sequences of N-Glycoproteins Including a β-D-Mannosidic LinkageThe trisaccharides α-D-Man-p-(1 → 6)-β-D-Man-p-(1 → 4)-D-GlcNAc (37) and α-D-Man-p-(1 → 3)-β-D-Man-p-(1 → 4)-D-GlcNAc (43) as well as the key tetrasaccharide α-D-Man-p-(1 → 3)-[α-Man-p-(1 → 6)]-β-D-Man-p-(1 → 4)-D-GlcNAc (51), which are parts of the carbohydrate chain of N-glycoproteins, have been synthesized. In this case the most important reaction is the direct synthesis of a β-mannoside linkage of D-mannos with 2-acetamido-2-deoxy-D-glucose. This problem has been solved by coupling of the halide 10 with the hydroxy component 14 in the presence of silver silicate which leads to the disaccharide 17. The product 17 is the fundamental compound for building up more complexed oligosaccharides.
    Notes: Die im Kohlenhydrat-Teil von N-Glycoproteinen enthaltenen Trisaccharide α-D-Man-p-(1 → 6)-β-D-Man-p-(1 → 4)-D-GlcNAc (37) und α-D-Man-p-(1 → 3)-β-D-Man-p-(1 → 4)-D-GlcNAc (43) und das Schlüsseltetrasaccharid α-D-Man-p-(1 → 3)-[α-D-Man-p-(1 → 6)]-β-D-Man-p-(1 → 4)-D-GlcNAc (51) wurden synthetisiert. Die wichtigste Reaktion ist hierbei die direkte Herstellung der β-D-mannosidischen Verknüpfung zwischen D-Mannose und 2-Acetamido-2-desoxy-D-glucose. Die Verknüpfung gelingt durch Umsetzung des Halogenids 10 und der Hydroxylkomponente 14 mit Hilfe des Silbersilicat-Verfahrens zum Disaccharid 17. Das Produkt 17 ist die Schlüsselsubstanz für alle weiteren Aufbaureaktionen zu höheren Oligosacchariden.
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  • 26
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding bacteria, XV. - Myxalamides A, B, C, and D, a Group o Homologous Antibiotics from Myxococcus xanthus Mx x12 (Myxobacterales)A new antibiotic complex, called myxalamides, was isolated from the cells of Myxococcus xanthus Mx x12 (GBF). After preliminary purification using florisil the myxalamides were separated by reversed-phase chromatography to give four components. The spectroscopic investigation of the main component, myxalamide B (1), revealed the structure of an alaninol amide with a highly unsaturated, branched fatty acid. The xyxalamides A (3), C(4) D(5) are amides of homologous fatty acids and alaninol.
    Notes: Aus den Zellen von Myxococcus xanthus Mx x12 (GBF) wurde ein neuer Antibiotika-Komplex, genannt Myxalamide, isoliert. Nach Vorreinigung an Florisil wurden die myxalamide durch chromatographie an einer Umkehrphase in vier Komponenten aufgetrennt. Die spektroskopische Untersuchung der Hauptkomponente, Myxalamid B (1), ergibt die Struktur eines Alaninolamids mit einer verzweigten, hohungesättigten Fettsäure. Die Myxalamide A (3), C(4) und D(5) sind Amide aus homologen Fettsäuren und Alaninol.
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  • 27
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with Nitriles, LXVIII. - 4-Dicyanomethylene-1,4-Dihydropyrimidines and Pyrido [4,3-d]pyrimidine-8-carbonitriles from EnaminonitrilesReaction of “dimeric malononitrile” (1a) or 3-amino-2-cyano-crotononitrile (1b) with dimethyl-formamide dimethyl acetal gives the biscondensation products 2. Subsequent treatment of 2a with ammonia and 2b with primary aliphatic amines leads to 4-dicyanomethylene-1,4-dihydropyrimidines 3. There are several possible structures for the reaction products obtained from 2a and primary aliphatic and aromatic amines. The structure of the product from 2a and propylamine is confirmed by X-ray structure analysis as 5,6-dihydro-5-imino-6-propyl-4-(propylamino)pyrido[4,3-d] pyrimidine-8-carbonitrile (4c). Hydrolysis of 4 in acidic medium leads to the 5-oxo derivatives 5.
    Notes: Reaktion von “dimerem Malononitril” (1a) oder 3-Amino-2-cyancrotonsäurenitril (1b) mit Dimethylformamid-dimethylacetal ergibt die Biskondensationsprodukte 2. Die Umsetzung von 2a mit Ammoniak oder 2b mit primären aliphatischen Aminen führt zu 4-Dicyanmethylen-1,4-dihydropyrimidinen 3. Für die Reaktionsprodukte aus 2a mit primären aliphatischen und aromatischen Aminen sind mehrere isomere Strukturen möglich. Die Röntgenstrukturanalyse des Produktes von 2a mit Propylamin sichert die Struktur eines 5,6-Dihydro-5-imino-6-propyl-4-(propylamino)pyrido[4,3-d]pyrimidin-8-carbonitrils (4c). Saure Hydrolyse von 4 liefert die 5-Oxo-Derivate 5.
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  • 28
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1116-1132 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: α-Oxo- and α-Thioxothioamides from Methyl KetonesMixtures of α-(chloro)sulfenyl chlorides 5 and trisulfides 6 are obtained from the reaction of thionyl chloride with methyl ketones in the presence of pyridine. From these mixtures as well as from the pure trisulfides 6, with amines the α-oxothioamides 1-4 are formed with good yields. Thionation of the thioamides 1 and 2 yields the deeply coloured α-thioxothioamides 16 and 17, the structure of which has been especially characterized by X-ray structure analyses.
    Notes: Bei der Reaktion von Methylketonen mit Thionylchlorid in Gegenwart von Pyridin entstehen Gemische aus α-(Chlor)sulfenylchloriden 5 und Trisulfiden 6, die - ebenso wie die reinen Trisulfide 6 - mit Aminen hohe Ausbeuten an α-Oxothioamiden 1-4 liefern. - Schwefelung der Thioamide 1 und 2 ergibt die tieffarbigen α-Thioxothioamide 16 und 17, deren Struktur insbesondere durch Röntgenstrukturanalysen charakterisiert wird.
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  • 29
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Syntheses via Heterocyclic Intermediates, XVIII. - On the Enantioselective Synthesis of (2R)-Serines Starting with The Bis(lactim) Ether of Cyclo-(-L-Val-Gly)The lithiated bis(lactim) ether 8a furnishes with aldehydes and ketones in good yields the addition products 11 with (3R) configuration. The asymmetric inductions at C-3 of 11 (d.e. values) amount to more than 95% with ketones, with aldehydes they are somewhat smaller. With unsymmetrical ketones or aldehydes C-3′ also becomes a chiral center. For the (3R)-major diastereomers the „second induction“ at C-3′ varies from about 4 to about 87% (for benzaldehyde or isobutyraldehyde, respectively), preferably the (3R,3′S) epimers are formed. - Acid hydrolysis of 11 yields (besides methyl L-valinate) the (2R)-serine methyl esters 26. Their e.e. values correspond with the d.e. values of 11. - Dehydratation of 11 furnishes the „Hofmann olefins“ 32 and/or the „Saytzeff olefins“ 33 which can be transformed in various ways into optically active amino acids.
    Notes: Der lithiierte Bislactimether 8a liefert mit Aldehyden oder Ketonen in guten Ausbeuten die Produkte 11 mit (3R)-Konfiguration. Die asymmetrischen Induktionen an C-3 (d.-e.-Werte von 11) betragen bei Ketonen mehr als 95%, bei Aldehyden sind sie etwas geringer (Tabelle 1). Bei unsymmetrischen Ketonen oder Aldehyden wird auch C-3′ zu einem Chiralitätszentrum. Bei den (3R)-Hauptdiastereomeren betragen die „Zweitinduktionen“ an C-3′ ca.4 bis ca. 87% (z. B. Benzaldehyd oder Isobutyraldehyd); vorzugsweise entstehen die (3R,3′S)-Epimeren (Tabelle 1). - Bei der sauren Hydrolyse der Addukte 11 erhält man (neben Methyl-L-valinat) die (2R)-Serin-methyl-ester 26, deren e.-e.-Werte an C-2 der asymmetrischen Induktion an C-3 von 11 entsprechen. - Die Dehydratisierung von 11 führt zu den „Hofmann-Olefinen“ 32 und/oder den „Saytzeff-Olefinen“ 33, die verschiedenartig zu optisch aktiven Aminosäuren abwandelbar sind.
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  • 30
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1162-1168 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereochemistry of Dehydration and Halogenation of αR* and αS* Isomeric 3-(α-Hydroxybenzyl)-1,4-diphenyl-2-azetidinonesDehydration with p-tosyl chloride in pyridine starting with the αR* isomers of the title compounds 3 results in formation of (E)-3-arylmethylene-β-lactams 4. (Z)-4 is obtained by starting with αS* isomeric 3. Halogenation of αS*-3 with thionyl chloride in chloroform yields αR* halogeno compounds 6 by inversion at C-α, and dehydrohalogenation of 6 by amines results in the specific formation of (E)-4.
    Notes: Die Dehydratisierung mit p-Tosylchlorid in Pyridin ergibt aus den αR*-Isomeren der Titelverbindungen 3 nur die (E)-3-Arylmethylen-β-lactame 4 und ausgehend von den αS*-Isomeren von 3 nur die (Z)-Isomeren 4. Aus αS*-3 werden durch Halogenierung mit Thionylchlorid in Chloroform unter Inversion an C-α die αR*-Halogenverbindungen 6 erhalten, deren Dehydrochlorierung spezifisch zu (E)-4 führt.
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  • 31
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1207-1214 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of 2-Aminomethylene-5-halo-2H-pyrroles and 5-Halo-2-pyrrolecarbaldehydes, II.  -  Cyclotetramerizations of Suitable Pyrroles into Octamethylporphyrins without Acid CatalysisCyclotetramerizations of 2-aminomethyl- and 2-dimethylaminomethyl-3,4-dimethylpyrrole with dimethyl sulfate, methyl iodide, copper(II) acetate, zinc acetate, magnesium chloride, hydroperoxide, formaldehyde, benzaldehyde, and ethylmagnesium bromide have been investigated. The syntheses of the pyrroles 4-6, 8, and 9 are described.
    Notes: Die Cyclotetramerisierungen von 2-Aminomethyl- und 2-Dimethylaminomethyl-3,4-dimethylpyrrol mit Dimethylsulfat, Methyliodid, Kupfer(II)-acetat, Zinkacetat, Magnesiumchlorid, Wasserstoffperoxid, Formaldehyd, Benzaldehyd und Ethylmagnesiumbromid werden untersucht. Die Synthese der Pyrrole 4-6, 8 und 9 wird beschrieben.
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  • 32
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1223-1233 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Some β-Mycaminose GlycosidesStarting from derivatives of 3-azido-3,6-dideoxy-α-α-glucofuranose 5 or 3-azidoglucofuranose 10 the 1-bromides 7, 14 and 30, suitable for glycoside synthesis under Koenigs-Knorr conditions, have been prepared. By reaction of 14 with methanol, cyclohexanol, benzyl alcohol, 2,2,2-trichloroethanol, and 1,2;3,4-di-O-isopropyliden-α-galactose the β-glycosides 16-20 are obtained in high yields. Reductive alkylation of 16, 17, and 20 with palladium on charcoal/formaldehyde gave the 3-dimethylamino compounds 21, 22, and 23. After their dehalogenation with tributyltin hydride, the corresponding β-glycosides 24, 25, and 26 of D-Mycaminose are received in high yields.
    Notes: Ausgehend von Derivaten der 3-Azido-3,6-didesoxy-α-D-glucofuranose 5 oder 3-Azidoglucofuranose 10 werden die für die Glycosidsynthesen unter Koenigs-Knorr-Bedingungen geeigneten 1-Bromhalogenosen 7, 14 und 30 dargestellt. Die Umsetzung von 14 mit Methanol, Cyclohexylalkohol, Benzylalkohol, 2,2,2-Trichlorethanol und 1,2;3,4-Di-O-isopropyliden-α-D-galactose führt in hohen Ausbeuten zu den β-Glycosiden 16-20. Die reduktive Alkylierung von 16, 17 und 20 mittels Palladiums auf Kohle/Formaldehyd-führt zu den 3-Dimethylaminoverbindungen 21, 22 und 23. Deren Enthalogenierung mit Tri-n-butylzinnhydrid verläuft in hohen Ausbeuten zu den entsprechenden β-Glycosiden 24, 25 und 26 der D-Mycaminose.
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  • 33
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 265-274 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Di- and Polyamino Sugars, XXVIII1). - Substitution Reactions of 2-Amino-2-deoxy-α-D-gluco-pyranosides at Position 3Nucleophilic substitutions of N-protected 2-amino-2-deoxy-3-O-mesyl-α-D-glucopyranosides with azide ions were severely restricted by neighboring group participations. N-acetyl as blocking group (2) led to the formation of the oxazoline 3 while from N-dinitrophenyl derivatives (9; 17) isomeric products (10, 11; 18, 19) were formed via epimines. Structure proofs were given by spectroscopy as well as by independent syntheses.
    Notes: Nucleophile Substitutionen an N-geschützten 2-Amino-2-desoxy-3-O-mesyl-α-D-glucopyranosiden mit Azid-Ionen wurden durch Nachbargruppenreaktionen behindert. N-Acetyl als Schutz-gruppe (2) führte zum Oxazolin 3, aus Dinitrophenyl-Derivaten (9; 17) wurden über Epimine isomere Produkte (10, 11; 18, 19) erhalten. Die Konstitutionsbeweise wurden sowohl anhand der Spektren als auch durch unabhängige Synthesen geführt.
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  • 34
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 282-297 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sulfosilylation of Aromatic Hydrocarbons by Trimethylsilyl ChlorosulfonateAromatic hydrocarbons 2, 6, 8, 9, 13, 16, 18, 19, 22 react with trimethylsilyl chlorosulfonate (1) to give trimethylsilyl arenesulfonates 5, 7, 11, 12, 15, 23 or sulfonic acids 17, 20, 21. If trimethylsilyl sulfonates are obtained, working up of the sulfonation mixtures is possible by distillation. By hydrohalogenolysis of trimethylsilyl sulfonates 5 at 0-5°C anhydrous sulfonic acids 3 result. The pathways to diphenylsulfone (25a) in the reaction of benzene (2a) with 1 were investigated. In this connection we succeeded in synthesizing benzenepyrosulfonic acid (28) and trimethylsilyl benzenepyrosulfonate (29).
    Notes: Durch Umsetzung der Aromaten 2, 6, 8, 9, 13, 16, 18, 19, 22 mit Chlorsulfonsäure-trimethylsilylester (1) erhält man die Arensulfonsäure-trimethylsilylester 5, 7, 11, 12, 15, 23 bzw. Sulfonsäuren 17, 20, 21. Die Aufarbeitung der Sulfonierungsgemische erfolgt, wenn Silylester entstehen, destillativ. Aus der Hydrohalogenolyse der Trimethylsilylester 5 bei 0-5°C resultieren die wasserfreien Sulfonsäuren 3. Am Beispiel der Reaktion von Benzol (2a) mit 1 werden die Möglichkeiten der Bildung von Diphenylsulfon (25a) untersucht. In diesem Zusammenhang gelang die Synthese von Benzolpyrosulfonsäure (28) und Benzolpyrosulfonsäure-trimethylsilylester (29).
    Additional Material: 11 Tab.
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  • 35
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Structure of a New Nortriterpene from the Bulbs of Scilla scilloides Druce1)From the acetone extract of the bulbs of Scilla scilloides Druce (Liliaceae) the new nortriterpene 1 has been isolated. The structure of 1 was established on the basis of chemical and spectral evidences. Besides the free state 1 was obtained by mild acid hydrolysis of the acetone-insoluble and methanol-soluble fraction suggesting the existence of 1 also in the form of its glycosides.
    Notes: Aus dem Acetonextrakt der Bulbi von Scilla scilloides Druce (Liliaceae) wurde das neue Nortriterpen 1 isoliert. Auf Grund der chemischen und spektroskopischen Untersuchungen ließ sich die Struktur von 1 ermitteln. Neben dem frei enthaltenen 1 wurde offenbar glycosidisch gebundenes 1 bei der milden Säurehydrolyse der in Aceton unlöslichen und in Methanol löslichen Fraktion erhalten.
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  • 36
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Theoretical and Spectroscopical Investigations of Indigo Dyes, XXII.  -  Preparations of 5,5′-and 6,6′-Dialkylated Indigo DyesThe manifolded applicabilities of indigo dyes are strongly restricted by the low solubility of most of their representatives. We describe in this paper the preparation of a series of dialkylated indigos 1, thioindigos 2, dyes of the cibaviolett-type 3, and of the corresponding vinylogues 4, 5, and 6 by different synthetic methods. Some of the prepared compounds show a remarkable solubility and can be used for spectroscopic measurements even in non-polar solvents.
    Notes: Die vielseitigen Verwendungsmöglichkeiten der Indigoide werden durch die geringe Löslichkeit der meisten Vertreter dieser Farbstoffklasse stark eingeschränkt. Wir berichten hier über die Darstellung einer Reihe dialkylierter Indigos 1, Thioindigos 2, Cibaviolett-Farbstoffe 3 sowie ihrer Vinylogen 4, 5 und 6 auf unterschiedlichen Wegen. Einige der Verbindungen zeigen eine sehr gute Löslichkeit und können in unpolaren Lösungsmitteln für spektroskopische Zwecke genutzt werden.
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  • 37
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1354-1360 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sugar Tosylates via p-Toluenesulfinic Acid Esters.  -  p-Toluenesulfinimidazolide  -  A Reagent for Formation of Sulfinic Acid Esters without Using HalidesThe reaction of the protected sugar derivatives 1, 4, 7, 10, 13, 16, 19 and 20 with p-toluenesulfin-imidazolide prepared from p-toluenesulfinic acid and N,N'-carbonyldiimidazole yields the corresponding p-toluenesulfinic esters 2, 5, 8, 11, 14, 17, 20 and 22. With the exception of 20 and 22, these products can be oxidized with m-chloroperbenzoic acid in high yields and short overall reaction times to the tosylates 3, 6, 9, 12, 15 and 18.
    Notes: Durch Umsetzung der blockierten Zuckerderivate 1, 4, 7, 10, 13, 16, 19 und 21 mit dem aus p-Toluolsulfinsäure und N,N'-Carbonyldiimidazol intermediär gebildeten p-Toluolsulfinimidazolid werden die p-Toluolsulfinsäureester 2, 5, 8, 11, 14, 17, 20 und 22 erhalten. Daraus lassen sich mit Ausnahme von 20 und 22 in hohen Ausbeuten und insgesamt kurzer Reaktionszeit die entsprechenden Tosylate 3, 6, 9, 12, 15 und 18 durch Oxidation mit m-Chlorperbenzoesäure darstellen.
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  • 38
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1361-1366 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Condensed Azoles with Two Bridgehead Nitrogen AtomsThe pyrazolo[1,2-a][1,2,4]triazoles 4, 1,2,4-triazolo[1,2-b]phthalazine 7, 1,2,4-triazolo[1,2-a]-[1,2,4]triazine 9, 1,2,4-triazolo[1,2-a]indazoles 16, 1,2,3,5-thiatriazolo[2,3-a]indazole 17 and 1,2,4-triazino[1,2-a]indazole 18 are prepared by the cycloreaction of the triazoles 1 or the triazole and indazole carboxamides 5, 6, 13, and 14 with 1,1-, 1,2-, 1,3-, and 1,4-dielectrophiles.
    Notes: Die Pyrazolo[1,2-a][1,2,4]triazole4, das 1,2,4-Triazolo[1,2-b]phthalazin 7, 1,2,4-Triazolo[1,2-a]-[1,2,4]triazin 9, die 1,2,4-Triazolo[1,2-a]indazole 16, das 1,2,3,5-Thiatriazolo[2,3-a]indazol 17 und 1,2,4-Triazino[1,2-a]indazol 18 werden durch Cycloreaktion der Triazole 1 bzw. der Triazol-und Indazolcarboxamide 5, 6, 13 und 14 mit 1,1-, 1,2-, 1,3- und 1,4-Dielektrophilen dargestellt.
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  • 39
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1345-1353 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methyl 2,5:3,6-Dianhydro-D-mannofuranosidesMonotosylation of methyl 3,6-anhydro-β-D-glucofuranoside gives as minor reaction product 1 which yields by treatment with sodium ethanolate methyl 2,5 : 3,6-dianhydro-β-D-mannofuranoside (2). The α-anomer 6 is equally prepared from 3 which is obtained by selective monotosylation of methyl 3,6-anhydro-β-L-gulofuranoside. Reaction of methyl 3,6-anhydro-2,5-di-O-tosyl-α-D-glucofuranoside (5) gives only small amounts of 6 accompanied by the monotosylate 4. Mass and NMR spectra (2D-1H and 13C) of the new dianhydrides 2 and 6 are described.
    Notes: Monotosylierung von Methyl-3,6-anhydro-bT-D-glucofuranosid ergibt als Nebenprodukt 1, dessen Behandlung mit Natrium-ethanolat zum Methyl-2,5 : 3,6-dianhydro-β-D-mannofuranosid (2) führt. Das entsprechende α-Anomere 6 kann analog aus 3, dem Produkt der selektiven Monotosylierung des Methyl-3,6-anhydro-β-L-gulofuranosids erhalten werden. Hingegen liefert die Umsetzung des Methyl-3,6-anhydro-2,5-di-O-tosyl-α-D-glucofuranosids (5) nur geringe Mengen 6 neben Monotosylat 4. Die NMR-Spektren (2D-1H und 13C) sowie der massenspektrometrische Zerfall der neuen Dianhydride 2 und 6 werden beschrieben.
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  • 40
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1393-1408 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methylketene: Synthesis by Pyrolysis of Butanone and Reaction with Imines Yielding Methylated AzetidinonesDuring the pyrolysis of acetone with a ketene lamp trace amounts of butanone and methylketene are produced. These compounds result from break-off reactions of radical reaction chains of acetone. Pyrolysis of butanone leads to a mixture of ketene (70%) and methylketene (30%). The latter reacts with imines to give methylated β-lactams. The rate of these cycloaddition reactions is several powers of ten greater than the one observed with ketene. The 8-methyl-5-azanonamdienes 7, 10, 26, and 31 are obtained in good yields when the corresponding diazepines are reacted with the pyrolysis gas of butanone. Similar experimental conditions lead to the methylated azetidinones 13, 15, 16, and 18 in moderate yields whereas the known thiazolines 19, 20, and 21 do not react at all. The action of 26 and 30 against several pathogenic bacterial strains was tested; however, no antibacterial properties could be detected.
    Notes: Die Bildung sehr kleiner Mengen von Butanon und Methylketen während der Pyrolyse von Aceton mit einer Ketenlampe wird als Ergebnis einer radikalischen Kettenreaktion nachgewiesen. Die Pyrolyse von Butanon unter den gleichen Bedingungen führt zu einem Gemisch von Keten (70%) und Methylketen (30%). Letzteres reagiert mit Iminoderivaten um einige Zehnerpotenzen schneller als Keten selbst, wobei methylierte β-Lactame entstehen. Auf diese Weise werden in guten Ausbeuten die trans-8-Methyl-5-aza-1,3-nonamdienderivate 7, 10, 26, 29 und 31 sowie in mäßigen Ausbeuten die monocyclischen methylierten Azetidinone 13, 15, 16 und 18 erhalten. Die bekannten Thiazolinderivate 19, 20 und 21 reagieren jedoch nicht mit dem pyrolytisch erzeugten Methylketen. Das 5-Azanonamdien-5-carboxamid 26 sowie die 5-Azanonamdien-1-carbonsäure 30 zeigen kein antibiotisches Verhalten gegenüber verschiedenen pathogenen Bakterienstämmen.
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  • 41
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1415-1418 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stable Carbenium Ions, 271). - Diarylchlorocarbenium IonsDiarylchlorocarbenium hexachloroantimonates have been prepared as crystalline salts and are characterised.
    Notes: Diarylchlorcarbenium-hexachloroantimonate werden als kristalline Salze dargestellt und charakterisiert.
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  • 42
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stable Carbenium Ions, 281). - α,α′-Dihalogen-α,α′-diphenyl-m-phenylenedicarbenium Ionsα,α′-Difluoro-α,α′-diphenyl-m-phenylenedicarbenium hexafluoroantimonate and α,α′-dichloro-α,α′-diphenyl-m-phenylenedicarbenium hexachloroantimonate are prepared as crystalline salts and are characterised.
    Notes: α,α′-Difluor-α,α′-diphenyl-m-phenylendicarbenium-hexafluoroantimonat und α,α′-Dichlor-α,α′-diphenyl-m-phenylendicarbenium-hexachloroantimonat werden als kristalline Salze dargestellt und charakterisiert.
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  • 43
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1194-1201 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polyacetylenic compounds, 268. - further Unsaturated Amides From achillea SpeciesThe roots of Achillea ageratifolia afforded in addition to a known C16-acetylenic carbonic acid amides five new ones, the N-isobutylamide 1, the 2,3-didehydropyrrolidides 4-6, and the pyrrolidide 3. Furthermore, the C10-acetylenic carbonic acid coniferyl esters 13 and 14 were isolated. The roots of Achillea falcata contain four known unsaturated C10-carbonic acid amides and two new ones, the piperidide 7 and the 4-hydroxy-2,3-didehydropiperidide 10. The structures were elucidated by spectroscopic methods. The chemotaxonomic significance of the amides is briefly discussed.
    Notes: Wurzeln von Achillea ageratifolia ergeben neben einem bekannten C16-Acetylencarbonsäureamid fünf neue, das N-Isobutylamid 1, die 2,3-Didehydropyrrolidide 4-6 und das Pyrrolidid 3. Außerdem isoliert man die C10-Acetylencarbonsäureconiferylester 13 und 14. Wurzeln von Achillea falcata enthalten vier bekannte ungesättigte C10-Carbonsäureamide und zwei neue, das Piperidid 7 und das 4-Hydroxy-2,3-didehydropiperidid 10. Die Strukturen wurden durch spektroskopische Methoden geklärt. Die chemotaxonomische Bedeutung der Amide wird kurz diskutiert.
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  • 44
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1237-1248 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Meerwein Saponification of Alkyl 3-Oxoalkanoates in the Gas ChromatographAlkyl 3-oxoalkanoates decompose by unevitable traces of water in the gas chromatograph to yield the corresponding methyl ketones and alcohols (Meerwein saponification1)). Decomposition occurs in the hot injector (T = 270°C) of the gas chromatograph and also on glass capillary columns (T ≥ 160°C). Decomposition in routine work can be avoided by preparing the corresponding 3-trimethylsilyl enol ethers.
    Notes: 3-Oxoalkansäure-alkylester werden durch Wasserspuren, die sich in der Praxis nicht ausschließen lassen, im Gaschromatographen (GC) zu entsprechenden Methylketonen und alkoholen zersetzt (Meerwein-Verseifung1)). Die Zersetzung erfolgt sowohl im heißen Injektorsystem (T = 270°C) des Gaschromatographen als auch auf Glaskapillarsäulen (T ≥ 160°C). Sie läßt sich durch Überführung in die entsprechenden 3-Trimethylsilylenolether vermeiden.
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  • 45
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diastereoselective Thermal or Acid-catalyzed Rearrangement of N,N′-Dibenzylidene-1,2-cyclopropanediamines to cis-2,3-Diaryl-2,3-dihydro-1H-1,4-diazepinesThe trans-N,N′-dibenzylidene-1,2-cyclopropanediamines t1a-g and t6a,b are obtained in the reaction of the trans-1,2-cyclopropanediamines t4 and t5, respectively, with aromatic aldehydes. In contrast, only the cis-N,N′-disalicylidene-1,2-cyclopropanediamines c1b and c6b can be isolated when the aromatic aldehydes are allowed to react with the cis-1,2-cyclopropanediamines c4 and c5, respectively. In the other cases, the intermediate cis-bisimines isomerize in situ to yield the cis-2,3-diaryl-2,3-dihydro-1H-1,4-diazepines c3a-d and 7a, respectively. In [D5]bromobenzene solution, the isolated bisimines t1a, c-e, g and c6b, t6a rearrange above 90°C to give the corresponding dihydrodiazepines c3a, c-e, g and 7a, b, in the neat, molten state above 120°C. Surprisingly, in acetate-buffered methanol solution the dihydrodiazepines c3a, d, are also formed in the reaction of trans-1,2-cyclopropanediammonium bromide (t4 · 2 HBr) with aldehydes at temperatures as low as 20°C. The diastereoselective step of these isomerizations, i. e. the Cope rearrangement of the cis-bisimines c1 and c6, is fast even at 20°C. The cis-bisimines c1 and c6 arise via a thermal or acid-catalyzed trans cis diastereomerization when the sequence starts from trans-1,2-cyclopropanediamine derivatives. All 2,3-diaryl-2,3-dihydrodiazepines which were obtained through rearrangement possess exclusively the cis configuration as shown by comparision with the authentic pair of diastereomers c3a, t3a and by 1H NMR spectroscopy. The 1H NMR spectra of the cis-2,3-dihydrodiazepinium cations c3 · H⊕ in trifuoroacetic acid indicate slow ring inversion up to 20-25°C. The free enthalpies of activation for the diastereotopomerization of 2-H and 3-H of the cis- 1,4,6-D3]-2,3-dihydrodiazepinium cations in [D]trifluoroacetic acid range from Δ G≠361≈ 60 (for c3b) to Δ G≠361 = 75.5 kJ/mol (for c3g). Besides slow ring inversion, teh free base c3g as well as the cation c3g · H⊕ exhibit slow rotation of the 2,4,6-trimethylphenyl groups at C3 and C3.
    Notes: Aus den trans-1,2-Cyclopropandiaminen t4 und t5 und aromatischen Aldehyden erhält man die trans-N,N′-Dibenzyliden-1,2-cyclopropandiamine t1a-g bzw. 16a,b. Dagegen lassen sich bei der Umsetzung aromatischer Aldehyde mit den cis-1,2-Cyclopropandiaminen c4 und c5 nur die cis-N,N′-Disalicyliden-1,2-cyclopropandiamine c1b bzw. c6b isolieren. In den anderen Fällen isomerisieren sich die intermediären cis-Bisimine in situ zu den cis-2,3-Diaryl-2,3-dihydro-1H-1,4-diazepinen c3a-d bzw. 7a. Die isolierten Bisimine t1a,c-e,g und c6b, t6a lassen sich in [D5]Brombenzol erst bei 90°C, in der Schmelze oberhalb 120°C, in die entsprechenden Dihydrodiazepine c3a,c-e,g bzw. 7a,b umlagern. Überraschenderweise entstehen in Acetat-gepuffertem Methanol die Dihydrodiazepine c3a, d auch aus dem trans-1,2-Cyclopropandiammoniumbromid (t4 · 2HBr) und Aldehyd, und zwar schon bei 20°C. Der diastereoselektive Schritt dieser Isomerisierungen ist eine schon bei 20°C rasche Cope-Umlagerung der cis-Bisimine c1 und c6. Diese entstehen durch thermische oder bei 20°C säurekatalysierte trans → cis-Diastereomerisierung, wenn man von trans-1,2-Cyclopropandiamin-Derivaten ausgeht. Alle durch Umlagerung erhaltenen 2,3-Diaryl-2,3-dihydro-1H-1,4-diazepine besitzen cis-Konfiguration, was durch Vergleich mit dem authentischen Diastereomerenpaar c3a, t3a und 1H-NMR-spektroskopisch bewiesen wurde. Die 1H-NMR-Spektren der cis-2,3-Dihydrodiazepinium-Kationen c3·H⊕ in Trifluoressigsäure zeigen noch bei 20-25°C langsame Ringinversion an. Die Freien Aktivierungsenthalpien der Diastereotopomerisierung von 2-H und 3-H der cis-[1,4,6-D3]-2,3-Dihydrodiazepiniumkationen in [D]Trifluoressigsäure betragen ΔG313≠ ≈ 60 (c3b bis ΔG≠361 = 75.5 kJ/mol (c3g). Die freie Base c3g und das Kation c3g · H⊕ zeigen neben langsamer Ringinversion auch noch langsame Rotation der beiden 2,4,6-Trimethylphenylgruppen an C2 und C3.
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  • 46
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Bile Pigments, XIII1).  -  Preparation of 3,4-Dihydro-5(1H)-pyrromethenones from 5(1H)-Pyrromethenones and from 5(2H)-Dipyrrylmethanones5(2H)-Dipyrrylmethanones 2 which are usually obtained by catalytical hydrogenation of 5(1H)-pyrromethenones 1, are only formed as the main product (ca. 80%) in alkaline solutions. In the absence of base, the obtained mixture contains up to 40% of the cis-configurated (Z)-3,4-dihydro-5(1H)-pyrromethenones (rac-3). On the other hand, the corresponding trans-isomers (rac-7) are available by base-catalyzed, irreversible rearrangement of 2 in boiling methanol in max. 40% yield. Under the same conditions (Z)-cis-3,4-dihydro-5(1H)-pyrromethenones (rac-3) are converted into the corresponding trans-isomers (rac-7), which can be isolated in 80% yield from the reaction mixture. In H3COD the products are deuterated at C-4 and at the methine bridge. (Z)-trans-3,4-Dihydro-5(1H)-pyrromethenones (rac-7) exchange only the H-atom at the methine bridge. Both cis- (rac-3) and trans-(Z)-3,4-dihydro-5(1H)-pyrromethenones (rac-7) can be transformed into the corresponding E-isomers rac-10 and rac-11, respectively, by photoisomerization at the exocyclic double bond.
    Notes: 5(2H)-Dipyrrylmethanone 2, die bekanntlich durch katalytische Hydrierung von 5(1H)-Pyrromethenonen 1 zugänglich sind, werden nur in alkalischem Medium als Hauptprodukte (ca. 80%) gebildet. In Abwesenheit von Base enthält das Produktgemisch bis zu 40% cis-konfigurierte (Z)-3,4-Dihydro-5(1H)-pyrromethenone (rac-3). Ihre trans-konfigurierten Z-Isomeren (rac-7) sind durch basenkatalysierte irreversible Umlagerung von 2 in siedendem Methanol in max. 40proz. Ausbeute zugänglich. Unter denselben Bedingungen isomerisieren cis-konfigurierte (Z)-3,4-Dihydro-5(1H)-pyrromethenone (rac-3) zu den entsprechenden (Z)-trans-Isomeren (rac-7), die in 80proz. Ausbeute isoliert werden können. In H3COD findet dabei H/D-Austausch an C-4 und an der Methin-Brücke statt. (Z)-trans-3,4-Dihydro-5(1H)-pyrromethenone (rac-7) tauschen dagegen nur das methinständige H-Atom aus. Sowohl cis- (rac-3) als auch trans-konfigurierte (Z)-3,4-Dihydro-5(1H)-pyrromethenone (rac-7) lassen sich in die entsprechenden E-Stereo-isomeren rac-10 bzw. rac-11 durch Photoisomerisierung der exocyclischen Doppelbindung über-führen.
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  • 47
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1513-1514 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Cyclisation of Salicylamides and Salicylohydroxamic Acids with 1,1′-CarbonyldiimidazoleCyclisation of salicylamides 1a, b and salicylohydroxamic acids 1c, d with 1,1′-carbonyldiimid-azole (2) causes formation of 2H-1,3-benzoxazine-2,4(3H)-diones 4a-d. In contrast to statements in the literature isoimides 3 or isoxazoles 5 could not be isolated.
    Notes: Salicylsäureamide 1a, b und Salicylohydroxamsäuren 1c, d cyclisieren mit 1,1′-Carbonyldiimid-azol (2) zu 2H-1,3-Benzoxazin-2,4(3H)-dionen 4a-d. Isoimide 3 oder Isoxazole 5 konnten entgegen Literaturangaben nicht isoliert werden.
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  • 48
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1523-1533 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dihydropyridines, VI1).  -  Derivatives of Diimido Malonic Acid in the Hantzsch Pyridine SynthesisOne-pot-condensation of aldehydes 6, 2,2′-methylenediimidazoline hydrochloride (7) and β-dicarbonyl compounds 10 leads to 1,2,3,7-tetrahydro-8-(2-imidazoline-2-yl)imidazo[1,2-a]pyridine hydrochloride 11. Michael addition of 7 to α,β-unsaturated ketones is followed by ring closure to give 16, 17, and 18. Condensation of the free base 8a with aldehydes 6 and 1,3-cyclohexanedione yields the fused imidazopyridines 19a-d. Compounds 20 and 21 are prepared by use of a second enamine in the one-pot-synthesis, thus furnishing another basic centre. 2,2′-Methylenedi(2-thiazoline) hydrochloride (22) is prepared by condensation of diethyl malonodiimidate and 2-amino
    Notes: Die Dreikomponenten-Kondensation von Aldehyden 6, 2,2′-Methylendiimidazolin-hydrochlorid (7) und β-Dicarbonylverbindungen 10 führt zu 1,2,3,7-Tetrahydro-8-(2-imidazolin-2-yl)imidazo-[1,2-a]pyridin-hydrochloriden 11. Die Verbindungen 16, 17 und 18 werden durch cyclisierende Michael-Addition von 7 an α,β-ungesättigte Ketone erhalten. Die freie Base 8a kondensiert mit 1,3-Cyclohexandion und den Aldehyden 6 zu den anellierten Imidazopyridinen 19a-d. Einsatz eines zweiten Enamins in der Dreikomponenten-Reaktion liefert die Verbindungen 20 und 21 mit einem weiteren basischen Zentrum. 2,2′-Methylendi(2-thiazolin)-hydrochlorid (22) wird durch Kondensation von Malondiimidsäure-diethylester und 2-Aminoethanthiol-hydrochlorid erhalten. Natronlauge liefert die freie Base 8b. Die 2,3-Dihydro-8-(2-thiazolin-2-yl) 7H-thiazolo[3,2-a]-pyridine 23, 25, 26, 28 und 29 sind durch cyclisierende Michael-Addition von 8b an verschiedene α,β-ungesättigte Carbonylverbindungen in Ethanol oder Eisessig zugänglich.
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  • 50
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1545-1549 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Malonodiamidines, III.  -  Synthesis and Condensation Reactions of 1,2,3,4,6,7-Hexahydro-7 imino-1,4-dimethyl-5H -1,4-diazepin-5-oneDiethyl malonodiimidate dihydrochloride (I) and N-methylethylenediamine yield in ethanol the N,N'-bridged malonodiamidine salt 2b, whereas 1 and N,N'-dimethylethylenediamine fail to give the 2b analogous salt 4. Instead the 1 H-1,4-diazepine-5,7-diimine hydrochloride 5 is obtained in low yield. Under hydrolytic reaction conditions the hydrochloride of the title compound is obtained in 56% yield. [3 + 3]-Condensations of the corresponding base 7 with 2,4-pentanedione and α,β-unsaturated carbonyl compounds lead to the diazepines 8, 9, and 10. 1 H-[1,4]diazepino-[5,6-b]quinolines 12a- f are obtained by condensation of 6 with the isatines 11.
    Notes: Malondiimidsäure-diethylester-dihydrochlorid (1) liefert mit N-Methylethylendiamin in Ethanol das N,N'-verbrückte Malondiamidiniumsalz 2b. Umsetzung von 1 mit N,N'-Dimethylethylendiamin führt wider Erwarten nicht zum 2b analogen Salz 4, sondern in geringer Ausbeute zum 1 H-1,4-Diazepin-5,7-diiminsalz 5. Unter hydrolytischen Reaktionsbedingungen wird das Hydrochlorid der Titelverbindung mit 56% Ausbeute erhalten. Die zugrundeliegende Base 7 geht mit 2,4-Pentandion und α,β-ungesättigten Carbonylverbindungen [3 + 3]-Kondensationen zu den Diazepinen 8, 9 und 10 ein. Die Isatine 11 kondensieren mit 7 zu den 1 H-[1,4]Diazepino[5,6-b]-chinolinen 12a- f.
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  • 51
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensations with Oxime O-Sulfonates, I.  -  Synthesis of 2-Amino-4,5-dihydro-4,5-diimino-1 H-pyrrole-3-carboxylatesThe reaction of the oxime O-tosylates 1 with the amidinoacetic acid esters 2 does not lead to the expected pyrazines 4, but rather to the novel 4,5-dihydro-1 H-pyrrole-3-carboxylates 8 (= 2-pyrroline-3-carboxylates) by rearrangement via 7. The hydrolysis of the pyrroles 8 and their reactions with amines have been studied.
    Notes: Die Reaktion der Oxim-O-tosylate 1 mit den Amidinoessigestern 2 führt nicht zu den erwarteten Pyrazinen 4, sondern unter Umlagerung über 7 zu den neuartigen 4,5-Dihydro-1 H-pyrrol-3-carbonsäureestern 8 (= 2-Pyrrolin-3-carbonsäureester). Die Hydrolyse der Pyrrole 8 sowie deren Umsetzung mit Aminen wird untersucht.
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  • 52
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1598-1607 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sulfur Compounds in Crude Oil, III. - Dihydrodiindeno[b,d]thiophenesSyntheses to the dihydrodiindeno[b,d]thiophenes 1-3 have been studied. 1-3 were prepared by thermolysis of 8H-indeno[1,2-d]-1,2,3-thiadiazole (10) or 4H-indeno[2,1-d]-1,2,3-thiadiazole (13) or by reduction of the corresponding diketones 17, 19, and 21 which were obtained by thermolysis of indeno[1,2-d]-1,2,3-thiadiazol-8-one (16) or from 2,3-dichloroinden-1-one (23) with Na2S. Mechanisms with analogous intermediates explain the formation of the indenothiphenes. - Another synthesis of diindeno[1,2-b:2′,1′-d]thiophene-10,11-dione (21) starts from 2,5-diphenyl-3,4-thiophenedicarboxylic acid (29). - 10,11-Dihydrodiindeno[1,2-b:2′,1′-d]thiophene (3) is the known sulfurization product of hydrindene, the structure of 3 is corrected.
    Notes: Synthesen zu den Dihydrodiindeno[b,d]thiophenen 1-3 wurden untersucht. 1-3 entstehen bei der Thermolyse des 8H-Indeno[1,2-d]1,2,3-thiadiazols (10) oder 4H-Indeno[2,1-d]1,2,3-thiadiazols (13) oder durch Reduktion der zugehörigen Diketoverbindungen 17, 19 und 21, die zugänglich sind durch Thermolyse des Indeno[1,2-d]-1,2,3-thiadiazol-8-ons (16) oder aus 2,3-Dichlorinden-1-on (23) mit Na2S. Mechanismen mit analogen Intermediaten erklären die Bildung der Indenothiophene. - Eine weitere Synthese des Diindeno[1,2-b:2′,1′-d]thiophen-10,11-dions (21) geht von der 2,5-Diphenyl-3,4-thiophendicarbonsäure (29) aus. - 10,11-Dihydrodiindeno-[1,2-b:2′,1′-d]thiophen (3) ist das bekannte Schwefelungsprodukt des Indans; die Struktur von 3 wird richtiggestellt.
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  • 53
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1638-1639 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conversion of Phenolic α-Amino Acids into α-Keto acidsA one-pot conversion of tyrosine (1a) and 3,4-dihydroxyphenylalanine (DOPA) (1b) into 3-(4-hydroxyphenyl)pyruvic acid (2a) and 3-(3,4-dihydroxyphenyl)pyruvic acid (2b), respectively, via 2-trifluoromethyl-3-oxazolin-5-ones 5 is described.
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  • 54
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from gliding Bacteria, XVII. - Myxopyronin A and B - Two Novel Antibiotics from Myxococcus fulvus Strain Mx f50From the gliding bacterium Myxococcus fulvus strain Mx f50 two antibiotics, named myxopyronin A and B, have been isolated and shown to possess the structures 9a and 9b. The two new compounds are 3-acyl-4-hydroxy-α-pyrones with an N-alkenylcarbamate function uncommon to natural products.
    Notes: Aus dem Kulturüberstand des Gleitenden Bakteriums Myxococcus fulvus Stamm Mx f50 (Myxobacterales) wurden zwei Myxopyronin A und B genannte Antibiotika isoliert und konstitutionell aufgeklärt. Es handelt sich um die Verbindungen 9a, b mit einer 3-Acyl-4-hydroxy-α-pyron-Struktur und einer für Naturstoffe ungewöhnlichen N-Alkenyl-Carbamat-Funktion.
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  • 55
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Synthesis of Both Enantiomers of (E)-4,6-Dimethyl-6-octen-3-one- Defensive Substance of “Daddy Longlegs” Leiobunum vittatum and L. calcar (Opiliones)The acyclic enone (E)-4,6-dimethyl-6-octen-3-one (1) is the major component of the defensive secretion of “daddy longlegs” Leiobunum vittatum and L. calcar (Opiliones). Both antiomers [(S)-1 and (R)-1] as well as racemic 1 are conveniently synthesized from diethyl ketone 2 and the bromide 3 by employing the hydrazone method. It is shown by LIS-NMR technique that the acyclic ketone alkylation occurs with virtually complete asymmetric induction ≥ 97%).
    Notes: Das acyclische Enon (E)-4,6-Dimethyl-6-octen-3-on (1) ist die Hauptkomponente Abwehrsekrets der Weberknechte Leiobunum vittatum und L. calcar (Opiliones). Beide Enantiomere [(S)-1 und (R)-1] sowie racemisches 1 werden bequem aus Diethylketon 2 und dem Bromid 3 unter Verwendung der Hydrazon-Methode synthetisiert. Durch LIS-NMR-Technik gezeigt, daß die acyclische Ketonalkylierung mit praktisch vollständiger asymmetrische? On erfolgt (ee ≥ 97%).
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  • 56
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 57
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1455-1458 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Type of Sesquiterpene Lactones from Lychnophora sallicifoliaFrom the polar fractions of Lychnophora salicifolia two new sesquiterpene lactones were isolated, the structures of which have been elucidated by high field 1H-NMR spectroscopy and by partial synthesis of one of the epimeric lactones which are derived from caryophyllene.
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  • 58
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclen-Synthese mit α,β-ungesättigten Nitrilen: Die Reaktion von β-(2-furanyl)- und β-(2-Thienyl)acrylonitrilen mit CH-acide MethylenverbindungenReaktionen von β-(2-Furanyl)- und β-(2-Thienyl)acrylonitilen mit verschiedenen CH-aciden Methylenverbindungen werden beschrieben. Die Untersuchungen erschließen einige neue Pyran- und Pyranodiazo-Derivate.
    Notes: The reactions of β-(2-furanyl)- and β-(2-thienyl)acrylonitrile with a variety of active methylene reagents are described. The investigations make several new pyran and pyranodiazle derivatives accessible.
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  • 59
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1504-1509 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 3-Pyrrolin-2-ones from Alcohol and Amine Adducts of TrichloroallenecarboxamidesOn treatment of the tetrachloro-substituted amide 1 with methoxide (1:10) in methanol the chlorine-free pyrrolinone 5 is formed. This reaction is interpreted via the allene 2 and its methanol adduct 3. According to the same principle the allene amine adducts 4 yield with methoxide at room temperature the intermediates 6 and in boiling methanol the chlorine-free pyrrolinone 8. Hydrolysis of 6 to 10 requires strong hydrochloric acid. Analogous ring closure of 4 occurs with amines to 9. Elimination of the last chlorine atom with methoxide leads from 9b to the pyrrolinonimine 13c.
    Notes: Bei der Behandlung des tetrachlorsubstituierten Amids 1 mit Methylat (1:10) in Methanol entsteht das chlorfreie Pyrrolinon 5. Die Reaktion verläuft über das Allen 2 und das Methanol-addukt 3. Nach dem gleichen Prinzip liefern die Allen-Aminaddukte 4 mit Methylat bei Raumtemperatur die Zwischenprodukte 6 und in siedendem Methanol die chlorfreien Pyrrolinone 8. Die Hydrolyse von 6 zu 10 erfordert starke Salzsäure. Ein analoger Ringschluß von 4 mit Aminen liefert 9. Die Eliminierung des letzten Chloratoms mit Methylat führt von 9b zu dem Pyrrolinonimin 13c.
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  • 60
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1510-1523 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 4-(1-Azi-2,2,2-trifluorethyl)benzoesäure, eine hoch lichtempfindliche carben-bildende, leicht an biochemische Wirkstoffe anknüpfbare VerbindungDie Titelverbindung wird ausgehend von (4-Brombenzyl)(tert-butyldimethylsilyl)ether (5b) oder von (4-Brombenzyl)(tert-butyl)ether (5c) oder, am einfachsten, von 4-Bromtoluol (5a) synthetisiert. Hierzu wird Br mit Hilfe von n-Butyllithium durch Li ersetzt und durch Reaktion der metallorganischen Verbindung mit N-Trifluoracetylpiperidin das entsprechende Trifluoracetophenon erhalten. Die Herstellung der Azigruppe (Diazirin) erfolgt über die Oxime 7a-c, deren O-Tosylverbindungen 8a-c, die mit Ammoniak die Diaziridine 9a-c bilden, welche dann mit Ag2O zu den Diazirinen oxidiert werden. Oxidation mit Permangant - bei den Etherverbindungen nach Etherspaltung mit Säure - ergibt die Titelverbindung 12. Bei Bestrahlung mit Licht (λ 〉 300 nm) spaltet 12 mit einer Halbwertszeit von 22 s N2 ab unter Carbenbildung. Gleichzeitig entsteht aus 12 zu etwa 20% die gelbe isomere 4-(1-Diazo-2,2,2-trifluorethyl)benzoesäure (20), die zum selben Carben wie 12 photolysiert wird. Die Synthese von 20 ausgehend von 4-Brombenzaldehyd wird beschrieben. Das Diazirin 12 kann als N-Hydroxysuccinimidester oder mit anderen Methoden der Amidsynthese sehr einfach an Aminogruppen biochemisch interessanter Substanzen geknüpft und zur Photoaffinitätsmarkierung eingesetzt werden.
    Notes: The title compound is synthesized starting from either 4-bromobenzyl tert-butyldimethylsilyyl ether (5b) or 4-bromobenzyl tert-butyl ether (5c) or - most simply - from 4-bromotoluene (5a). In the first step Br was replaced by Li using n-butyllithium, then the organometallic compounds were converted into the respective trifluoroacetophenones 6a-c with N-trifluoroacetylpiperidine. The azi moiety (diazirine) was prepared from the oximes 7a-c viaO-tosyloximes 8a-c plus ammonia yielding the diaziridines 9a-c and oxidation of the latter with Ag2O. Oxidation by permanganate - of the ethers after acidic cleavage - yields the title compound 12. On irradiation (λ 〉 300 nm) 12 by elimination of N2 with a half-life period of 22 s generates the corresponding carbene. At the same time from 12 with ca. 20% the yellow isomeric 4-(1-diazo-2,2,2-trifluoroethyl)benzoic acid (20) is formed which is photolyzed generating the same carbene as 12. The synthesis of 20 is described starting from 4-bromobenzaldehyde. - The diazirine 12 as its N-hydroxysuccinimide ester 13, or using other methods of amide synthesis, can readily be coupled to amino functions of biochemically interesting agents thus forming photoaffinity labels.
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  • 61
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antamanide, XXXV. - Synthesis of [6-(L-2,6-Diamino-4-hexynoic acid)]antamanide as Precursor of a 3H-labelled [6-Lysine]antamanide for Photoaffinity LabellingL-2,6-Diamino-4-hexynoic acid, protected at its 2-amino group be 1-(3,5-dimethoxyphenyl)-1-methylethoxycarbonyl (Ddz) and at its 6-amino group by tert-butyloxycarbonyl (Boc), is coupled to the nonapeptide ester H-Pro-Pro-Phe-Phe-Val-Pro-Pro-Ala-Phe-OMe (3-OMe). The decapeptide 5 so obtained, after deprotection of its terminals is cyclisized by N,N′-dicyclohexylcarbodiimide/N-hydroxysuccinimide to yield the ∊-Boc-protected 6-analogue Boc-2 of antamanide. This, by catalytical hydrogenation yields [∊-Boc-Lys6]antamanide (Boc-1) thus offering the possibility to introduce tritium into an antiphallotoxic active molecule. Acylation of the ∊-amino group of [Lys6]antamanide (1) by the previously4) described 4-(1-azi-2,2,2-trifluoroethyl)benzoic acid yields a derivative suitable for photoaffinity labelling.
    Notes: L-2,6-Diamino-4-hexinsäure, geschützt an der 2-Aminogruppe durch den 1-(3,5-Dimethoxyphenyl)-1-methylethoxycarbonylrest (Ddz), an der 6-Aminogruppe durch den tert-Butyloxycarbonylrest (Boc), wird mit dem Nonapeptidester H-Pro-Pro-Phe-Phe-Val-Pro-Pro-Ala-Phe-OMe (3-OMe) verknüpft und das erhaltene Decapeptid 5 nach Deblockierung der Enden mit N.N′- Dicyclohexylcarbodiimed/N-Hydroxysuccinimid zum ∊-Boc-Derivat Boc-2 des im Titel genannten Antamanid-Analogen cyclisiert. Dieses läßt sich katalytische zu [∊-Boc-Lys6]Antamanid (Boc-1) hydrieren, womit die Möglichkeit der Einführung von Tritium in das antiphallotoxinwirksame Molekül gegeben wird. Durch Acylierung der ∊-Aminogruppe des [Lys6]Antaminids (1) mit der bereits beschriebenen4) 4-(1-Azi-2,2,2-trifluorethyl)benzoesäure wird ein zur Photoaffinitätsmarkierung geeignetes Präparat erhalten.
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  • 62
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    Liebigs Annalen 1983 (1983), S. 1937-1949 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ring-Chain Isomerism of N-(3-Hydroxyalkyl)nitrones, I. - C-Aryl-N-(3-hydroxypropyl)nitronesN-(3-Hydroxypropyl) nitrones 5 are prepared from 3-(hydroxyamino) propanol 3 and aromatic aldehydes. The isomerism between the open-chain nitrone form 5 and the cyclic perhydro-1,3-oxazine form 6 is proved by formation of diphenylboron chelates 4 and N-acyloxy-perhydro-1,3-oxazines 10, respectively.
    Notes: Aus 3-(Hydroxyamino)propanol 3 und aromatischen Aldehyden werden N-(3-Hydroxypropyl)-nitrone 5 dargestellt. Die Isomerie zwischen offenkettiger Nitron-Form 5 und cyclischer Perhydro-1,3-oxazin-Form 6 wird durch Bildung von Diphenylborchelaten 4 bzw. N-Acyloxy-perhydro-1,3-oxazinen 10 nachgewiesen.
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  • 63
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 805-812 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regioselective Synthesis of the N-Monomethyl Derivatives of 7-DeazahypoxanthineMethylation of 3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one (1a) or its 2-methylthio derivative with dimethyl sulfate in alkaline solution leads preferentially to the 3-methyl derivatives 2a or 2b, respectively. The N-1 isomer 3, however, is obtained by condensation of ethyl 2-cyano-4,4-diethoxybutyrate with N-(methyl)thiourea via the pyrimidine 4a which after cyclisation to 5a was desulfurised to 3. Phase-transfer methylation of 4-methoxy-2-methylthio-7H-pyrrolo[2,3-d] pyrimidine furnishes 8a which after ether cleavage and desulfurisation gave the N-7-methyl isomer 8c.
    Notes: Die Methylierung von 3,7-Dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-on (1a) oder seines 2-Methylthioderivates mit Dimethylsulfat führt im alkalischen Medium bevorzugt zu den N-3-Methyl-Derivaten 2a bzw. 2b. Das N-Isomer 3 wird hingegen durch Kondensation von 2-Cyan-4,4-diethoxybuttersäure-ethylester mit N-(Methyl)thioharnstoff über das Pyrimidinderivat 4a durch Cyclisierung zu 5a und anschließende Desulfurierung erhalten. Phasentransfer-Methylierung von 4-Methoxy-2-methylthio-7H-pyrrolo[2,3-d]pyrimidin führt zu 8a, aus dem durch Etherspaltung und Entschwefelung das N-7-Methylisomer 8c entsteht.
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  • 64
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    Liebigs Annalen 1982 (1982), S. 817-820 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eine kurze Synthese von MuscimolMuscimol (1) wurde, ausgehend von Acetylendicarbonsäure-dimethylester (3) und N-Hydroxyharnstoff, in 3 Schritten mit 30proz. Ausbeute synthetisiert.
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  • 65
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Microbiological Formation of 2-(4-Bromophenyl)-2-ethoxyoxirane and Crystal Structure Determination of the Dimerization Product meso-2,5-Bis(4-bromophenyl)-2,5-diethoxy-1,4-dioxanep-Bromo-2-hydroxyacetophenone (3) is metabolized by baker's yeast to give the optically active epoxy ether 1a which is stable in crystalline form. The structural assignment is based mainly on the NMR spectra. - The stereochemical course of the dimerization to the 1,4-dioxane derivative 2a is discussed on the basis of the X-ray structure of the dimer.
    Notes: p-Brom-2-hydroxyacetophenon (3) wird durch Bäckerhefe zum optisch aktiven Epoxyether 1a metabolisiert, der im kristallinen Zustand stabil bleibt. Die Strukturzuordnung erfolgt im wesentlichen durch NMR-Spektren. - Der stereochemische Verlauf der Dimerisierung zum 1,4-Dioxan-derivat 2a wird auf der Basis der Röntgenstruktur des Dimeren diskutiert.
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  • 66
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1996-1999 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radical-induced Reduction of α,β-Unsaturated Steroid Ketones with Tributyltin HydrideConjugated steroid ketones are reduced stereoselectively with tributyltin hydride in the presence of azobisisobutyronitrile as radical initiator to give the corresponding saturated ketones in high yields.
    Notes: Konjugierte Steroidketone werden mit Tributylzinnhydrid in Gegenwart des Radikalbildners Azobisisobutyronitril stereoselektiv und in hohen Ausbeuten zu den gesättigten Ketonen reduziert.
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  • 67
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    Liebigs Annalen 1983 (1983), S. 2008-2020 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Clerodane Derivatives and Novel Diterpenes From Conyza scabrida DCThe careful separation of the extract of the aerial parts of Conyza scabrida afforded in addition to known compounds 12 new clerodane derivatives and 9 diterpenes with unusal carbon skeletons which most likely were formed in part by electrocyclic transformations of the clerodanes. The structures were elucidated by NMR studies. The chemotaxonomic situation is discussed briefly.
    Notes: Die sorgfältige Trennung des Extraktes der oberirdischen Teile von Conyza scabrida ergibt neben bereits bekannten Verbindungen 12 neue Clerodan-Derivate und 9 Diterpene mit ungewöhnlichen Kohlenstoffgerüsten, die wahrscheinlich teilweise durch elektrocyclische Umwandlungen der Clerodane gebildet werden. Die Strukturen werden durch NMR-Untersuchungen geklärt. Die chemotaxonomische Situation wird kurz diskutiert.
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  • 68
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of rac-4′-O-Methylglabridin, an Antimicrobial Prenylated Isoflavan from Glycyrrhiza glabra L.A synthesis of racemic -4′-O-methylglabridin (1) is described. The key steps are the transformation of the isoflavan-4-one 4 into a dithioacetal 5 followed by desulfuration with Raney nickel.
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  • 69
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    Liebigs Annalen 1983 (1983), S. 2038-2041 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Chemistry of Amino Oximes, XVII. - 1,8-Dioxa-2,5,9,12-tetraazacyclotetradeca-2,9-diene-6,13-diones from (E)-α-Aminoacetophenone Oxime DerivativesThe (E)-α-(Chloroacetylamino)acetophenone oximes 2a-c were cyclodimerised by alkali to give the title compounds 6a-c.
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  • 70
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    Liebigs Annalen 1983 (1983), S. 2049-2051 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of P1-(7-Methyl-5′-guanosyl_-P2-(5′-adenosyl) DiphosphateP1-(7-Methyl-5′-guanosyl)-P2-(5′-adenosyl)diphosphate (3), an analogue of the “cap” structure at the 5′-terminus of eukaryotic messenger RNA, was chemically synthesized and enzymatically identified. The synthesis, based upon the imidazolidate method1), was performed on a nanomolar scale.
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  • 71
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    Liebigs Annalen 1983 (1983) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 72
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    Liebigs Annalen 1983 (1983), S. 2052-2054 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enzymatische Trennung von L - Leucin und L,/-IsoleucinDie in ihren chemischen und physikalischen Eigenschaften sehr ähnlichen Aminosäuren L-Leucin und L-Isoleucin können getrennt werden, indem ein Gemisch dieser beiden Substanzen zu einer Mischung aus N-Acetyl-L-leucin und N-Acetyl-L-isoleucin acetyliert wird und diese Mischung bei neutralem pH-Wert einer substratselektiven Hydrolyse unter Einfluß von Nierenacylase unter-worfen wird. Dieses Verfahren erlaubt die Herstellung von hochreinem L-Leucin. Aus der Mutterlauge wird unverändertes N-Acetyl-L-isoleucin in einer Reinheit von 90-93% gewonnen. Hydrolyse mit Salzsäure und fraktionierende Kristallisation als Hydrochloridsalz erlaubt die Herstellung von reinem L-Isoleucin.
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  • 73
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Biologisch aktive Glycoside aus Asteroidea, V. - Steroid-Oligoglycoside aus dem Seestern Asterias amurensis [cf.] versicolor Sladen, 1. - Strukturermittlung eines neuen OligoglycosidsulfatsNeben den bereits bekannten Steroiden 3β,6α-Dihydroxy-5α-pregn-9(11)-en-20-on (1), 3β,6α,20ξ-Trihydroxy-5α-cholest-9(11)-en-23-on (2), 3β,6α,20ξ-Trihydroxy-24ξ-methyl-5α-cholest-9(11)-en-23-on (3) [isoliert in Form ihrer Acetate 1′, 2′ und 3′ aus dem enzymatischen Hydrolysat des Oligoglycosidgemischs] und Thornasterosid A (8) wurde ein neues, mit Versicosid A bezeichnetes genuines Oligoglycosidsulfat isoliert und dessen Struktur auf Grund chemischer und spektroskopischer Befunde als Mononatriumsalz von 6α-[(O-β-D-galactopyranosyl-(1→3)-O-β-D-fucopyranosyl-(1→2)-O-β-D-galactopyranosyl-(1→4)-O-[β-D-chinovopyranosyl-(1→2)]-O-β-D-xylopyranosyl-(1→3)-β-D-chinovopyranosyl)oxy]-20ξ-hydroxy-3β-(sulfooxy)-5α-cholest-9(11)-en-23-on (4) ermittelt.
    Notes: In addition to the already known 3β,6α-dihydroxy-5α-pregn-9(11)-en-20-one (1), 3β,6α,20ξ-trihydroxy-5α-cholest-9(11)-en-23-one (2), 3β,6α,20ξ-trihydroxy-24ξ-methyl-5α-cholest-9(11)-en-23-one (3) [isolated in the form of the diacetates 1′, 2′, and 3′ from the enzymatic hydrolyzate of an oligoglycoside mixture], and thornasteroside A (8) a new genuine oligoglycoside sulfate named versicoside A has been isolated and structurally elucidated by chemical and spectroscopic evidences as the monosodium salt of 6α-[(O-β-D-galactopyranosyl-(1→3)-O-β-D-fucopyranosyl-(1→2)-O-β-D-galactopyranosyl-(1→4)-O-[β-D-quinovopyranosyl-(1→2)]-O-β-D-xylopyranosyl-(1→3)-β-D-quinovopyranosyl)oxy]-20ξ-hydroxy-3β-(sulfooxy)-5α-cholest-9(11)-en-23-one (4).
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  • 74
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    Liebigs Annalen 1983 (1983), S. 2114-2126 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Enantiomerically Pure Building Blocks for Syntheses from Branched MalatesIsocitric acid lactone (13) and the chiral building blocks (2S,3R)-4-bromo-1,2-epoxy-3-methylbutane (21), cis- and trans-2,3-epoxy-2-methylsuccinates (23, 24), and the singly protected (2R)-2-methyl-, -2-allyl- and -2-benzyl-1,3-propanediols (32a, b, c) are readily accessible in diastereomerically and enantiomerically pure forms from malates (8, 16, 25a, b, c) which are alkylated in position 3.
    Notes: Ausgehend von in 3-Stellung alkylierten, enantiomerenreinen Äpfelsäureestern (8, 16, 25a-c) wurden (+)-Isocitronensäurelacton (13) sowie die Synthesebausteine (2S,3R)-4-Brom-1,2-epoxy-3-methylbutan (21), cis- und trans-2,3-Epoxy-2-methylbernsteinsäureester (23, 24) und die einfach geschützten (2R)-2-Methyl-, -2-Allyl- und -2-Benzyl-1,3-propandiole (32a, b, c) diastereomeren- und enantiomerenrein hergestellt.
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  • 75
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Branched Sugars, XXVII1).  -  Synthesis of Long Chain Saccharides by Chain Elongation with the Dianion of 1,3-Dithiane-2-methanol and Related DianionsThe dianions 3, 4, and 16, which are suitable for nucleophilic addition to aldehydo-saccharides, can be obtained by reaction of 1,3-dithiane-2-methanol, or the appropriate side chain-elongated derivatives, with 2 molar equivalents of butyllithium. With these dianions, chain elongated saccharides can be made and, in one step, various potential chiral centres may be introduced. The octose 18, the decose 21, and the undecose 22 are obtainable from 17. With 23, the elongation of the chain leads to the septose 25, the nonose 27, and the decose 28. A 2-septulose 35 and 5-deculose 37 were also made.
    Notes: Durch Umsetzung von 1,3-Dithian-2-methanol und entsprechenden an der Seitenkette verlängerten Derivaten mit 2 Moläquivalenten Butyllithium lassen sich Dianionen 3, 4 und 16 darstellen, die zur nucleophilen Addition an aldehydo-Saccharide geeignet sind. Dabei werden kettenverlängerte Saccharide erhalten, bei denen in einem Schritt mehrere vorgegebene chirale Zentren eingeführt werden können. Aus 17 sind so die Octose 18, die Decose 21 und die Undecose 22 zu erhalten. Mit 23 führt die Kettenverlängerung zur Septose 25, zur Nonose 27 und Decose 28. Auch eine 2-Septulose 35 und 5-Deculose 37 sind darstellbar.
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  • 76
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    Liebigs Annalen 1981 (1981), S. 2057-2060 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Configuration of NardosinoneX-ray analysis of nardosinone (1) shows cis position of the 1,2-dioxolane ring. Therefore, the formation of nardofuran (3) from isonardosinone (2) takes place by retention of the configuration at C-4.
    Notes: Die Röntgenstrukturanalyse zeigt, daß im Nardosinon (1) der 1,2-Dioxolan-Ring in cis-Stellung steht. Die Bildung des Nardofurans (3) aus Isonardosinon (2) verläuft daher unter Retention der Konfiguration an C-4.
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    Liebigs Annalen 1982 (1982), S. 989-993 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Contribution to the Addition of CH-acidic Compounds to the CC Triple BondIn an addition-isomerisation reaction α-alkyl- and α-arylbenzylcyanides 1 add phase-transfer catalysed to 1-propargylazoles 2 yielding substituted 4-azolyl-3-methyl-3-butenenitriles 3.
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  • 78
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    Liebigs Annalen 1982 (1982), S. 1001-1005 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass Spectrometric Analysis of Long-chain Alkatrienes  -  Evidence of a Structure Specific Diene FragmentEI mass spectra of 1,n,(n + 2)-alkatrienes show structure specific fragments which allow the determination of the double bond position.
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  • 79
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Complexes with Tetrapyrrole Ligands, XXXII. - Improved Procedure for Insertion of Osmium into Porphyrins, Carbonylosmium(II) Complexes of Mesoporphyrin IXAn improved procedure for the insertion of osmium into porphyrins is tested with mesotetra-(p-tolyl)porphyrin. Potassium hexachloroosmate, K2OsCl6, in diethyleneglycol monomethyl ether serves as metal carrier. The procedure allows the preparation of carbonyl(mesoporphyrinato-IX)pyridineosmium(II) which is now available for reconstitution experiments.
    Notes: Ein verbessertes Verfahren zum Einbau von Osmium in Porphyrine wird an Mesotetra(p-tolyl)-porphyrin erprobt. Als Metallspender dient Kaliumhexachloroosmat(IV), K2OsCl6, in Diethylenglycolmonomethylether. Das Verfahren ermöglicht die Darstellung von Carbonyl(mesoporphyrinato-IX)pyridinosmium(II), das nunmehr für Rekonstitutionsexperimente zur Verfügung steht.
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    Liebigs Annalen 1981 (1981), S. 2090-2092 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experiments Concerning the Reduction of Dichloromethanedisulfonyl DichlorideMild reducing agents, including methanol, reduce dichloromethanedisulfonyl dichloride (2) to give dichloro(chlorosulfonyl)methanesulfinic acid (6) which desulfinylates spontaneously to form dichloromethanesulfonyl chloride (9). Chloromethanedisulfonyl dichloride (12) ist not reduced under these conditions and can be derivatized „normally“, for instance with morpholine.
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    Liebigs Annalen 1981 (1981), S. 2097-2097 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 82
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    Liebigs Annalen 1983 (1983), S. 1689-1693 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of VerboccidentafuranStarting with the Diels-Alder adduct of 1-ethoxyisoprene and methoxyquinone the racemate of the furanocadinene derivative verboccidentafuran (15) from Verbesina occidentalis has been synthesized and with that its stereochemistry established.
    Notes: Ausgehend vom Diels-Alder-Addukt aus 1-Ethoxyisopren und Methoxychinon wurde das Racemat des Furanocadinen-Derivats Verboccidentafuran (15) aus Verbesina occidentalis synthetisiert und damit dessen Stereochemie gesichert.
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    Liebigs Annalen 1983 (1983), S. 1668-1688 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetrische Synthese von α-substituierten Aminosäuren und Aminen durch Kohlenstoff - Kohlenstoff-Verknüpfung in α-Stellung zum StickstoffBeschrieben wird die asymmetrische Synthese von α-substituierten α-Aminosäuren und Propargylaminen. Als chiralen Hilfsstoff benutzen wir (S)-(-)-1-Dimethoxymethyl-2-methoxymethyl-pyrrolidin (SDMP, 1). Die Aminosäuren und Amine werden mit SDMP 1 in die entsprechenden Amidine C übergeführt. Metallierung und Alkylierung ergibt die Produkte D, welche zu den gewünschten α-substituierten Aminosäuren 20 und Propargylaminen 22 hydrolysiert werden. Die Methode erlaubt die enantioselektive Alkylierung von Aminosäuren und Propargylaminen mit zufriedenstellenden chemischen Ausbeuten und genügender bis guter Enantioselektivität. Der chirale Hilfsstoff SDMP 1 wird aus (S)-Prolin in 4 Stufen hergestellt.
    Notes: The asymmetric synthesis of α-substituted α-amino acids and propargylamines is described. As chiral auxiliary we used (S)-(-)-1-dimethoxymethyl-2-methoxymethylpyrrolidine (SDMP, 1). Treatment of the amino acids or amines with SDMP 1 afforded the corresponding amidines C, which can be metalated and alkylated to yield the products D, which were hydrolyzed to give the desired α-substituted α-amino acids 20 and propargylamines 22. The method allows the enantioselective alkylation of amino acids and propargylamines in satisfactory chemical yields and fair to good enantioselectivity. The chiral auxiliary SDMP 1 is prepared from (S)-proline in 4 steps.
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    Liebigs Annalen 1983 (1983), S. 1739-1743 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: α-Oxosulfones, 5. - reactions of a Cyclic α-Ketosulfone5,5-Dioxo-6H-dibenzo[b,d]thiopyran-6-one (4) as the first „real α-ketosulfone“ was isolated, and some of its reactions were studied. Apparently, 4 represents formally a border case between a thioester S,S-dioxide and an „α-ketosulfone“.
    Notes: Als erstes „wirkliches α-Ketosulfon“ wurde 5,5-Dioxo-6H-dibenzo[b,d]-thiopyran-6-on (4) isoliert. Beim Studium einiger seiner Reaktionen zeigte sich, daß 4 formal einen Grenzfall zwischen einem Carbonsäurethioester-S,S-dioxid und einem „α-Ketosulfon“ darstellt.
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    Liebigs Annalen 1983 (1983), S. 1760-1797 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Constituents of Cneoraceae, VIII. - Pentanortriterpenes of the B- and C-Series, Olefins (I)The constitution and configuration of the fundamental cneorins B (2) and C (3) is elucidated by their chemical and spectroscopic properties and X-ray diffraction analysis. The acid-catalysed rearrangements of B (2) and C (3) to the cneorins BI (4),II (31), BIII (6) and CI (5), CII (32), CIII (7), respectively, is described.
    Notes: Die Konstitution und Konfiguration der grundlegenden Cneorine B (2) und C (3) wird durch chemischen Abbau, Auswertung der Spektren und Röntgenstrukturanalysen ermittelt. Die Säurekatalysierte Umlagerung von B (2) und C (3) zu den Cneorinen BI (4), BII (31), BIII (6), bzw. CI (5), CII (32), CIII (7) wird beschrieben.
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  • 86
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stellvertretende nucleophile Substitution von Wasserstoff in Nitropyridinen durch α-Chloralkylphenylsulfon-CarbanionenNitropyridine und Chlornitropyridine reagieren mit Carbanionen von α-Chloralkylphenylsulfonen unter „stellvertretender nucleophiler Substitution“ von Wasserstoff in o- und p-Stellung zur Nitrogruppe. Als allgemeine Regel wurde beobachtet, daß die „stellvertretende Substitution“ des Wasserstoffs rascher als die nucleophile Substitution von entsprechend aktiviertem Halogen erfolgt. Die Orientierung der Wasserstoff-Substitution wird diskutiert.
    Notes: Nitropyridines and chloronitropyridines react with carbanions of α-chloroalkyl phenyl sulfones yielding products of the vicarious nucleophilic substitution of hydrogen at positions ortho and para to the nitro group. A general rule that the vicarious substitution of hydrogen proceeds faster than the nucleophilic substitution of equally activated halogen is observed. The orientation of the hydrogen substitution is discussed.
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    Liebigs Annalen 1983 (1983), S. 1818-1838 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Anthracyclinones, XXII. - Rhodmycinones of Type A with methyl, ethyl, and n-Propyl Side ChainThe anthraquinone derivatives 7, 8, 37, 39, and 40 are prepared by addition of dichloromethyllithium to the corresponding ketones 4, 5, 32b, 34b, and 36b. They can be hydrolized to intermediate aldehydes, which cyclize after reduction to anthracyclinones of Type A with methyl group (11, 12a, 13a, 45, 46a, 47a), ethyl group (15a, 16a, 48, 49, 50a), and n-propyl side chain (51a, 52a). The cis/trans ratio of the 7,8-Diols is approximately 1 : 3. The hydroxy groups at C-10 are introduced stereoselectively to the 8,10-cis-diols 20b, 24, 25a, 53, 54, and 55 via bromination and hydrolysis of the bromides.
    Notes: Die Anthrachinonderivate 7, 8, 37, 39 und 40 werden durch Addition von Dichlormethyllithium an die entsprechenden Ketone 4, 5, 32b, 34b und 36b hergestellt. Sie lassen sich zu intermediären Aldehyden hydrolysieren, die nach Reduktion zu Anthracyclinonen vom Typ A mit Methylgruppe (11, 12a, 13a, 45, 46a, 47a), Ethylgruppe (15a, 16a, 48, 49, 50a) und n-Propylseitenkette (51a, 52a) cyclisieren. Das cis/trans-Verhältnis der 7,8-Diole beträgt etwa 1:3. Die Hydroxygruppen an C-10 werden stereoselektiv zu den 8,10-cis-Diolen 20b, 24, 25a, 53, 54 und 55 über Bromierung und Hydrolyse der Bromide eingeführt.
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  • 88
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Applications of Phase Transfer catalysis, 26. - Thioureas by Three-Component Reactions of Amines, Carbon Tetrachloride, and Sulfide IonsThe title reactions proceed exothermically in the presence of a phase transfer catalyst. Thiophosgene is an intermediate in this conversion, and its phase transfer catalytic transformation into carbon disulfide and trithiocarbonate can be demonstrated. Perchloromethanethiol/sodium sulfide and a PT catalyst yield thiophosgene too. Activated vicinal dibromides were debrominated by Na2S/catalyst.
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  • 89
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1859-1885 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycopeptide Synthesis: Selective C-Terminal Deblocking and Peptide Chain elongation of Glucosylserine DerivativesBenzyloxycarbonyl-(Z-)serine 2-bromoethyl ester (3b) reacts with 2,3,4,6-tetra-O-benzoyl-α-D-glucopyranosyl bromide (14) to give the glucosylserine ester 15. After conversion into the corresponding 2-iodoethyl ester 23 the carboxylic group is deblocked selectively by reductive elimination using zinc. In this procedure the Z and the carbohydrate protective functions as well as the sensitive O-glycoside bond remain unaffected. The glycosylserine 24 is condensed with amino acid 2-bromoethyl esters 2 to form protected glycodipeptide 2-bromoethyl esters 18 which are extended to give glycotripeptide esters 25 after selective carboxyl deblocking. Whereas protected serine dipeptides 5 are glycosylated with 14 to form the conjugates 18, the glycosylation of the serine tripeptides 10 was not successful.
    Notes: Benzyloxycarbonyl-(Z-)serin-2-bromethylester (3b) wird mit 2,3,4,6-Tetra-O-benzoyl-α-D-gluco-pyranosylbromid (14) zum Glucosylserinester 15 verknüpft. Nach Umwandlung in den entsprechenden 2-Iodethylester 23 wird die Carboxygruppe durch Eliminierung mit Zink selektiv deblockiert. Dabei bleiben die Z- und die Kohlenhydrat-Schutzgruppen sowie die empfindliche O-glycosidische Bindung unverändert erhalten. Das Glycosyl-Z-serin 24 reagiert mit Aminosäure-2-bromethylestern 2 zu geschützten Glycodipeptid-2-bromethylestern 18, die nach selektiver Carboxydeblockierung zu Glycotripeptidestern 25 C-terminal verlängert werden. Während geschützte Serin-Dipeptide 5 mit 14 zu Konjugaten 18 glycosyliert werden können, gelingt die Glycosylierung von Serin-Tripeptiden 10 nicht.
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  • 90
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1910-1919 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: α-Glucosidases Inhibitors, 2. - Synthesis of Modified MaltotriosesTwo pathways were developed for the synthesis of the 4″-amino-4″,6″-didesoxymaltotriose derivative 5, the O-protected terminal trisaccharide unit of acarbose. Glycosidation of the 4′-unprotected maltose derivative 3 with the trichloroacetimidate 2 of 4-azido-4,6-dideoxyglucose 1 led to the α- and β-connected trisaccharides 4 and 9. They were transformed into the O-protected amino sugars 5 and 10. In addition, from phenyl maltotrioside 15 the 4″,6″-unprotected derivative 19 was obtained; selective deoxygenation and azide introduction also led to compound 4 and 5.
    Notes: Für die Herstellung des 4″-Amino-4″,6″-didesoxymaltotriosederivats 5, der O-geschützten terminalen Trisaccharideinheit der Acarbose, wurden zwei Synthesewege entwickelt. Glycosidierung des 4′-ungeschützten Maltosederivats 3 mit dem Trichloracetimidat 2 der 4-Azido-4,6-didesoxyglucose 1 lieferte die α- bzw. β-verknüpften Trisaccharide 4 und 9, die in die O-geschützten Aminozucker 5 und 10 übergeführt werden. Außerdem wurde aus dem Phenylmaltotriosid 15 über das 4″,6″-ungeschützte Derivat 19 durch selektive Desoxygenierung und Azideinführung 4 und 5 daraus erhalten.
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  • 91
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2384-2391 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Natural γ- and δ-Lactones, XI.  -  Synthesis of Psilotin and 6-EpipsilotinThe glucoside psilotin (1) and its 6-epi isomer were synthesized. From CD measurements the 6S-configuration can be assigned to 1.
    Notes: Psilotin (1) und 6-Epipsilotin wurden synthetisiert. CD-Messungen an diesen Verbindungen legen für natürliches Psilotin die 6S-Konfiguration fest.
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  • 92
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 93
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2407-2418 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Syntheses via Heterocyclic Intermediates, X.  -  Enantioselective Synthesis of (2R)-2-MethylserinesAldehydes and ketones react with the lithiated bislactim ether 3 of cyclo-(L-Ala-L-Ala) with 81 to 〉 95% asymmetric induction (d. e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly.  -  A model concept for the asymmetric induction is proposed.  -  With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here [for the (3R)-isomers] with d. e. 47-73%. Hydrolysis of the addition products 6 (0.25 N HCl, room temperature) gives L-Ala-OCH3 and (2R)-2-methylserine methyl esters 7. Both compounds can be separated either at the ester stage by distillation or  -  if 7 is thermolabile  -  after further hydrolysis at the amino acid stage.
    Notes: Die Umsetzung des lithiierten Bislactimethers 3 von cyclo-(L-Ala-L-Ala) mit Aldehyden und Ketonen vollzieht sich mit 81 bis 〉 95% asymmetrischer Induktion (d. e. = diastereomeric excess) an C-3, wobei die (R)-Konfiguration induziert wird.  -  Eine Modellvorstellung zur Deutung dieser ungewöhnlich hohen Induktion wird diskutiert.  -  Bei Aldehyden oder unsymmetrischen Ketonen wird auch C-7 der Addukte 6 zu einem Chiralitätszentrum; hier wird [bei den (3R)-Isomeren] mit 47-73% d. e. ebenfalls (R)-Konfiguration induziert.  -  Hydrolyse der Addukte 6 (0.25 N HCl, Raumtemperatur) liefert neben L-Ala-OCH3 die (2R)-2-Methylserin-methylester 7. Die bei-den Verbindungen lassen sich entweder auf der Stufe der Ester destillativ trennen oder  -  wenn 7 thermolabil ist  -  nach weiterer Hydrolyse auf der Stufe der Aminosäuren.
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  • 94
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 28-40 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metabolic Products of Microorganisms, 2041) - The Structure of Imacidin CImacidin C, the main peptide antibiotic from Streptomyces olivaceus, has been identified as (R)-β-hydroxyisotridecanoic decapeptide lactone 5. This paper describes the analysis of its lactone linkage and amino acid sequence by chemical degradation and partial hydrolysis. The amino acid configuration was determinated enzymatically and by gas chromatography on chiral phase.
    Notes: Imacidin C, der Hauptbestandteil einer Gruppe chemisch ähnlicher Peptidantibiotica aus Streptomyces olivaceus, wurde als (R)-β-Hydroxyisotridecanoyl-decapeptidlacton 5 identifiziert. Aminosäuresequenz und Größe des Lactonringes wurden durch Partialhydrolyse und Abbaureaktionen ermittelt, die Konfiguration der Aminosäuren enzymatisch und durch Gaschromatographie an chiraler Phase bestimmt.
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  • 95
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbonyl und Thiocarbonylverbindungen: Reaktionen von 4-Chlorxanthion mit Diazoalkanen und Ch-aciden verbindungenWährend 4-Chlorxanthion 1 mit Diazomethan das Dithiolan 2 ergibt, entstehen mit anderen Diazoalkanen die Episulfide 3-5, deren Entschwefelung zu den entsprechenden Ethylenen 6-7 führt. Malononitril und Cyanessigsäure-ethylester reagieren mit 1 zu den Cyanderivaten 8a, b. Mit Hydrazinen und p-Toluidin ergibt 4-Chlorxanthion (1) die Hydrazone 9a, b und die Schiff-Base 9c. In Abhängigkeit von den Reaktionsbedingungen liefert die Oxidation des Hydrazons 9a die Diazoverbindung 10 oder das Ketazin 11. Hydroxylamin reagiert mit 1 zum Oxim 9d, das mit Phenylisocynat zum N-Phenylcarbamat 9e reagiert.
    Notes: While 4-chloroxanthione 1 gives with diazomethane the dithiol 2, it reacts with other diazoalkanes to give the episulfides 3-5, desulfurization of which forms the ethylenes 6 and 7. Malononitrile and ethyl cyanoacetate react with 1 to give the cyano derivatives 8a, b. With hydrazines and p-toluidine, 4-chloroxanthione (1) give the hydrazones 9a, b and the Schiff's base 9c, respectively. The hydrazone 9a on oxidation may give either the corresponding diazo compound 10 or the ketazine 11 according to the reaction conditions. The title compound 1 reacts with hydroxylamine to yield the oxime 9d which forms the N-phenylcarbamate 9e when treated with phenyl isocyanate.
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  • 96
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    Liebigs Annalen 1984 (1984), S. 196-198 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaktionen von 4-Chlor-9H-xanthen-9-thion mit Tetrachlor-O-benzochinon4-Chlor-9H-xanthen-9-thion (1) reagiert mit Tetrachlor-o-benzochinon zu dem cyclischen Acetal 2. Zur Struktursicherung wurde 2 auf unabhängigen Wegen aus Tetrachlor-o-benzochinon und 4-Chlor-9-diazo-9H-xanthen oder 4-Chlor-9H-xanthen-9-on-hydrazon sowie aus Tetrachlorbrenzcatechin und 4,9,9-Trichlor-9H-xanthen synthetisiert. Die Spaltung der Acetalgruppe in 2 mit Salzsäure, Malononitril, Cyanessigsäure-ethylester und Hydrazinhydrat wurde studiert.
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  • 97
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polyhydroxyamino Compounds via Diene Synthesis with Nitroso compounds, IX.  -  trans-6-Azido-1,3-cyclohexadien-5-ol as educt for the Synthesis of Kondurodiamine and Streptamine IsomersThe diaminodideoxykonduritols 8a, 8b, and 9 as well as the analogs 10 and 11 of Streptamine have been synthesized starting with O,N-5,6-disubstituted cyclohexadienes.
    Notes: Die Diaminodidesoxykondurite 8a, 8b und 9 sowie die Streptaminanalogen 10 und 11 werden ausgehend von O,N-5,6-disubstituierten Cyclohexadienen synthetisiert.
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  • 98
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    Liebigs Annalen 1982 (1982), S. 112-117 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Light-induced Reactions of Morphine Derivatives, 31) - 2nd Order Photo Beckmann RearrangementIrradiation of the oxime 1b leads to a fragmentation reaction, called second-order photo Beckmann rearrangement. A C-C bond is splitted with formation of a triple CN bond and a methoxy, ethoxy, or hydroxy group is introduced. On heating with acid, the nitriles 3a, b and 7a are transformed into the lactam 6.
    Notes: Die Bestrahlung des Oxims 1b führt zu einer als Beckmann-Reaktion 2. Art bezeichneten Fragmentierungsreaktion. Unter C-C-Bindungsspaltung kommt es zur Ausbildung einer CN-Dreifachbindung und zur Einführung einer Methoxy-, Ethoxy- oder Hydroxy-Gruppe. Beim Erhitzen mit Säure werden die Nitrile 3a, b und 7a in das Lactam 6 umgewandelt.
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  • 99
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    Liebigs Annalen 1982 (1982), S. 118-120 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Novel Dimeric Corrinoid with Bisallyl StructureOn thermolysis of heptamethyl dicyanocobyrinate (in decalin at 190°C), a dimer is formed (among other products) which according to its 13C and 1H-NMR data and its molecular mass possesses the structure of tetracyanobis(7-decarboxymethyl-7,8-didehydro-5-methylene-5-norcobyrinic acid) dodecamethyl ester (2).
    Notes: Bei der Thermolyse von Dicyanocobyrinsäure-heptamethylester (in Decalin bei 190°C) bildet sich u. a. ein Dimeres, dessen Konstitution sich aufgrund von 13C- und 1H-NMR-Daten sowie der Molmasse als Tetracyanobis(7-decarboxymethyl-7,8-didehydro-5-methylen-5-norcobyrinsäure)-dodecamethylester (2) ergibt.
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  • 100
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1366-1374 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of cis- and trans-Enynes in the Class of 12- and 15-membered Ring SystemsSynthesis of (E)-1-cyclododecen-3-yne (E-2a) leads to the isolation of the first trans-enyne with geometrical ring strain. E-2a isomerizes thermally to give the Z-configuration Z-2a in a very smooth reaction. For systematical investigations the 15-membered ring enynes E-5a and Z-5a were generated. They behave like openchained 1,3-enynes.
    Notes: Die Synthese von (E)-1-Cyclododecen-3-in (E-2a) führt zur Isolierung des ersten trans-Enins mit geometrischer Ringspannung. E-2a wandelt sich thermisch leicht in die Z-Konfiguration Z-2a um. Zur systematischen Untersuchung werden die 15-Ring-Enine E-5a und Z-5a hergestellt. Sie verhalten sich wie offenkettige 1,3-Enine.
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