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  • Organic Chemistry  (682)
  • 1980-1984  (682)
  • 1930-1934
  • 1925-1929
  • 1983  (682)
  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    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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  • 9
    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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  • 10
    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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  • 11
    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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  • 12
    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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  • 13
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    Electronic Resource
    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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  • 14
    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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  • 15
    Electronic Resource
    Electronic Resource
    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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  • 16
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    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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  • 17
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    Electronic Resource
    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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  • 18
    Electronic Resource
    Electronic Resource
    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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  • 19
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    Electronic Resource
    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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  • 20
    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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  • 21
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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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  • 22
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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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  • 23
    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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  • 24
    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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  • 25
    Electronic Resource
    Electronic Resource
    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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  • 26
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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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  • 27
    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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  • 28
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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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  • 29
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    Electronic Resource
    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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  • 30
    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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  • 31
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    Weinheim : Wiley-Blackwell
    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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  • 32
    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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  • 33
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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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  • 34
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    Weinheim : Wiley-Blackwell
    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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  • 35
    ISSN: 0170-2041
    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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  • 36
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    Weinheim : Wiley-Blackwell
    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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  • 37
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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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  • 38
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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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  • 39
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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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  • 40
    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).
    Additional Material: 2 Ill.
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  • 41
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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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  • 42
    ISSN: 0170-2041
    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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  • 43
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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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  • 44
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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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  • 45
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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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  • 46
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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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  • 47
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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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  • 48
    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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  • 49
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    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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  • 50
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    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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  • 51
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2045-2048 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Further Germacranolide with a β-Lactone Ring from Grazielia serrataThe reinvestigation of the aerial parts of Grazielia serrata afforded in addition to compounds isolated previously two germacranolides, 8β-angeloyloxy-9β-hydroxycostunolide and a further germacranolide with a β-lactone ring. The structure - 8β-tiglioyloxygrazielolide (1) - was elucidated by spectroscopic methods and by chemical transformation into the trans,trans-cyclodecadiene derivative 3.
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  • 52
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2073-2078 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Resolution of DL-CysteineThe diastereomeric 4-thiazolidinecarboxylic acids 3 and 4, obtained by condensation of DL-cysteine (DL-1) with D-(+)-galactose (2), can be separated by crystallization. Ring cleavage of 3 or 4 gives L-cysteine (L-1) or D-cysteine (D-1), respectively. Instead of D-(+)-galactose other chiral aldoses can be employed as resolution agents.
    Notes: Die bei der Kondensation von DL-Cystein (DL-1) mit D-(+)-Galactose (2) entstehenden zueinander diastereomeren 4-Thiazolidincarbonsäuren 3 und 4 lassen sich durch Kristallisation trennen. Bei der Ringspaltung von 3 bzw. 4 entstehen L-Cystein(L-1) bzw. D-Cystein (D-1). Statt D-(+)-Galactose kann man auch andere chirale Aldosen einsetzen.
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  • 53
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2066-2072 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphorpentoxid in der Organischen Synthese, VII. - Synthese von 3-Aryl-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-iminenDurch Umsetzung von 2-(Acetylamino)-3-pyrrolcarbonitrilen 1 mit einer Mischung von Phosphorpentoxid, N,N-Dimethylcyclohexanamin und einem geeigneten Arylamin-hydrochlorid bei 150-180 °C werden die Titelverbindungen 2 erhalten. Das verwendete Arylamin-hydrochlorid muß absolut wasserfrei sein, da anderenfalls 4-(Arylamino)pyrrolo[2,3-d]pyrimidine 4 als Nebenprodukte entstehen können. - Die Ergebnisse der Prüfung auf Pestizid- und Antikrebs-Wirksamkeit werden mitgeteilt.
    Notes: The title compounds 2 were prepared by treating 2-(acetylamino)-3-pyrrolecarbonitriles 1 with a mixture of phosphorus pentoxide, N,N-dimethylcyclohexanamine, and an appropriate arylamine hydrochloride at 150-180°C. The importance of using absolutely anhydrous arylamine hydrochlorides is stressed because failing this, 4-(arylamino)pyrrolo[2,3-d]pyrimidines 4 can be formed as by-products. - The results from pesticide and anticancer screenings are reported.
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  • 54
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2055-2065 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transformations with N-Acetylneuraminic Acid, 2From methyl 5-acetylamino-3,5-dideoxy-β-D-glycero-D-galacto-2-nonulopyranosidonic acid methyl ester (1) the 8,9-O-isopropylidene derivative 2 was obtained, which was transformed with pyridinium chlorochromate (PCC) or pyridinium fluorochromate (PFC) into the 4-keto derivative 3 (Scheme 1). Treatment of 2 with triphenylphosphane/diethyl azodicarboxylate and hydrazoic acid yields the oxazoline derivative 4. Compound 4 can be converted with hydrochloric acid in methanol to give the methyl 4-O-acetyl-5-acetylamino-3,5-dideoxy-β-D-glycero-D-talo-2-nonulopyranosidonic acid methyl ester (5a) and the derivatives 5b - d. methyl 5-acetylamino-7,8-anhydro-4,9-bis-O-(tert-butyldimethylsilyl)-3,5-dideoxy-α-L-glycero-2-nonulopyranosidonic acid methyl ester (6) and the analogous 7,8-anhydro-β-D-glycero-L-altro derivative 8 were transformed with chlorotrimethylsilane and sodium iodide into the corresponding 8-iodo-8-deoxy-β-D-glycero-d-galacto- or the 8-iodo-8-deoxy-α-L-glycero-L-altro-2-nonulopyranosidonic acid methyl ester derivatives 7b-d or 9b, respectively (Scheme 2). Treatment of 10 with N,N-dimethylformamide dimethyl acetal yields - via the intermediates 11 and 12 - either with acetic anhydride the epoxides 6 and 8 or with methyl iodide the methyl 5-acetylamino-4,9-bis-O-(tert-butyldimethylsilyl)-3,5,8-trideoxy-7-O-formyl-8-iodo-α-L-glycero-D-galacto-2-nonulopyranosidonic acid methyl ester (13) and the 7-deoxy-7-iodo-β-D-glycero-L-altro derivatives 14 and 14a. Reaction of 13, 14, or 14a with sodium methoxide yields the 7,8-anhydro-β-D_glycero-D-galacto-2-Nonulopyranosidonic acid methyl ester derivative 15, the 9-O_(tert-butyldimethylsilyl) group can be selectively removed with tetrabutylammonium fluoride to give 15a (Scheme 3). Structure elucidation was achieved by 1H NMR spectra of the corresponding acetates.
    Notes: Methyl-5-acetylamino-3,5-didesoxy-β-D-glycero-D-galacto-2-nonulopyranosidonsäure-methylester (1) wurde über das 8,9-O-Isopropylidenderivat 2 mit Pyridiniumchlorochromat (PCC) oder Pyridiniumfluorochromat (PFC) in das 4-Ketoderivat 3 übergeführt (Schema 1). Mit Triphenyl-phosphan/Azodicarbonsäure-diethylester und Stickstoffwassersäure ergibt 2 das Oxazolinderivat 4, das mit Salzsäure in Methanol in den Methyl-4-O-acetyl-5-acetylamino-3,5-didesoxy-β-D-glycero-D-talo-2-nonulopyranosidonsäure-methylester (5a) und die Derivate 5b-d umgewandelt wird. Der Methyl-5-acetylamino-7,8-anhydro-4,9-bis-O-(tert-butyldimethylsilyl)-3,5-didesoxy-α-L-glycero-D-galacto-2-nonulopyranosidonsäure-methylester (6) und das analoge 7,8-Anhydro-β-D-glycero-L-altro-Derivat 8 wurden mit Chlortrimethylsilan und Natriumiodid zu den entsprechenden 8-Iod-8-desoxy-β-D-glycero-D-galacto- bzw. 8-Iod-8-desoxy-α-L-glycero-L-altro-2-nonulopyranosidonsäure-methylester-Derivaten 7b-d bzw. 9b geöffnet (Schema 2). 10 liefert mit N,N-Dimethylformamid-dimethylacetal über die Zwischenstufen 11 und 12 mit Acetanhydrid die Epoxide 6 und 8 oder mit Methyliodid den Methyl-5-acetylamino-4,9-bis-O-(tert-butyldimethylsilyl)-3,5,8-tridesoxy-7-O-form yl-8-iod-α-L-glycero-D-galacto-2-nonulopyranosidonsäure-methylester (13) und die 7-Desoxy-7-iod-β-D-glycero-L-altro-Derivate 14 und 14a. 13, 14 und 14a können mit Natriummethanolat in das 7,8-Anhydro-β-D-glycero-D-galacto-2-nonulopyranosidonsäure-methylester-Derivat 15 übergeführt werden, dessen 9-O-(tert-Butyldimethylsilyl)-Gruppe selektiv mit Tetrabutylammoniumfluorid unter Bildung von 15a entfernt werden kann (Schema 3).
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  • 55
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2127-2134 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Ladbane Derivatives from Aristeguietia pseudoarboreaThe investigation of the aerial parts of Aristeguietia pseudoarborea afforded in addition to widespread compounds five new labdane derivatives the structures of which have been elucidated by spectroscopic methods and a few chemical transformations. The absolute configuration could be deduced from the positive Cotton effect of a ketone which was obtained by partial acetylation and oxidation of the main constituent.
    Notes: Die Untersuchung der oberirdischen Teile von Aristeguietia pseudoarborea ergab neben weitverbreiteten Verbindungen fünf neue Labdan-Derivate, deren Strukturen durch spektroskopische Methoden und einige chemische Umwandlungen geklärt wurden. Die absolute konfiguration wurde aus dem positiven Cotton-Effekt eines Ketons abgeleitet, das durch partielle Acetylierung und Oxidation der Hauptverbindung erhalten wurde.
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  • 56
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    Liebigs Annalen 1983 (1983), S. 2135-2140 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: High Pressure Experiments, XII. - Application of High Pressure on Wittig Reactions with Resonance Stabilized YlidesAt pressures of about 10 kbar the reaction of aldehydes with resonance stabilized ylides gets strongly accelerated. The yield of the trans-olefin is increased.
    Notes: Unter Druck von etwa 10 kbar wird die Reaktion von Aldehyden mit resonanzstabilisierten Yliden stark beschleunigt. Dabei wird der Anteil des trans-Olefins erhöht.
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  • 57
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    Liebigs Annalen 1983 (1983), S. 2151-2163 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Anthracyclinones, XXIII. - Synthesis and Configuration of the Stereoisomeric AklavinonesThe keto ester 19 is obtained via Arndt-Eistert homologisation of the anthraquinone carboxylic acid 17a. Base treatment of 19 leads to the epimeric cyclisation products 21 and 24. The methyl ethers 21 and 24 can be split to give the bisphenols 3 and 25. The hydroxy groups at C-4 are introduced via homolytic bromination and solvolysis with aqueous tetrahydrofuran. The products of natural configuration 3 and 21 mainly give the cis-2,4-diols 1a and 22 (cis/trans ≈ 10: 1) whereas the epimers 24 and 25 yield the trans-2,4-diols 27 and 6 as the main products (cis/trans ≈ 1:4).
    Notes: Der Ketoester 19 wird durch Arndt-Eistert-Homologisierung aus der Anthrachinoncarbonsäure 17a erhalten. Basenbehandlung von 19 führt zu den epimeren Cyclisierungsprodukten 21 und 24. Die Methylether 21 und 24 können mit Aluminiumchlorid zu den Bisphenolen 3 und 25 gespalten werden. Die Hydroxygruppen an C-4 werden durch homolytische Bromierung und Solvolyse mit wäßrigem Tetrahydrofuran eingeführt. Die Produkte natürlicher Konfiguration 3 und 21 liefern hauptsächlich die cis-2,4-Diole 1a und 22 (cis/trans ≈ 10: 1), während bei den Epimeren 24 und 25 die trans-2,4-Diole 27 und 6 überwiegen (cis/trans ≈ 1: 4).
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  • 58
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    Liebigs Annalen 1983 (1983), S. 2173-2184 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of the Tetrose Building Unit of the Chromomycinone Side Chain from D-GalactoseApplication of the reaction sequence isopropylidenation, benzylation, and acetal cleavage to ethyl β-D-galactofuranoside (1) leads to the diol 4. The fucose derivative 15 is prepared from 4 by different routes and further transformed into its methyl ether 17. Following hydrogenolysis to 18 this compound is oxidatively cleaved using periodic acid, and acetal formation yields the D-threose synthon 20 of the chromomycinone side chain.
    Notes: Aus Ethyl-β-D-galactofuranosid (1) wird nach Isopropylidenierung, Benzylierung und saurer Acetalspaltung das Diol 4 erhalten. Auf verschiedenen Wegen läßt sich daraus das Fucosederivat 15 darstellen und zum Methylether 17 umsetzen. Nach Hydrogenolyse zu 18 ist durch Periodatspaltung und saure Acetalisierung das D-Threose-Synthon 20 der Chromomycinon-Seitenkette zu gewinnen.
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  • 59
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2197-2214 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Stereochemistry of Iridoids, III. - About the Synthesis of 12-epi-ProstaglandinsA general applicable synthetic route to 12-epi-prostaglandins, which are difficult to prepare by known syntheses, is described. As examples the 12-epi-PGF2β (11) and its 15R epimer are synthesized. By alteration of the synthesis the already known PGF2β (11a) and its 15 R epimer can be prepared. The configurations of the obtained prostaglandins are established chemically and spectroscopically.
    Notes: Es wird ein allgemein anwendbarer Syntheseweg zu 12-epi-Prostaglandinen beschrieben, die nach den bekannten Synthesen nur schwer herstellbar sind. Als Beispiel wird das 12-epi-PGF2ß (11) und sein 15R-Epimeres synthetisiert. Durch Abwandlung der Synthese kann auch das schon bekannte PGF2β (11a) und sein 15R-Epimeres hergestellt werden. Die Konfigurationen der erhaltenen Prostaglandine werden chemisch und spektroskopisch bewiesen.
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  • 60
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloarene, eine neue Klasse aromatischer Verbindungen, III. - Studien zur Synthese des Cyclo[d,e,d,e,e,d,e,d,e,e]decakisbenzensVersuche zur Synthese des Cycloarens 2 aus Benzo[c]phenanthren-Bausteinen werden mitgeteilt: Aus 3, über dessen Darstellung auf verschiedenen Wegen berichtet wird, wurden die Bis(brommethyl)- und Bis(mercaptomethyl)-Verbindungen 4 bzw. 5 erhalten. Cyclisierung von 4 und 5 ergab 12, aus dem durch Schwefel-Extrusion das carbocyclische System 14 dargestellt wurde. Stevens-Umlagerung von 12 und nachfolgende Eliminierung lieferten 17. Scholl-Reaktion von 14 führte durch nur einseitige Cyclisierung zur Bildung von 18. Ähnlich ergab die Photo-Cyclodehydrierung von 17 nicht 2, sondern 19. - Das neue helicale aromatische System, das in 18 und 19 vorliegt, wird auf der Grundlage spektroskopischer Ergebnisse diskutiert.
    Notes: Attempts to synthesize the cycloarene 2 starting from benzo[c]phenanthrene building blocks are reported: From 3, the preparation of which along different routes is dealt with, bis(bromomethyl) and bis(mercaptomethyl) derivatives 4 and 5, respectively, were obtained. Cyclisation of 4 and 5 yielded 12 from which by sulfur extrusion the carbocyclic system 14 was prepared. Stevens rearrangement of 12 and subsequent elimination yielded 17. Scholl reaction of 14 resulted in the formation of 18 by only one-sided cyclisation. Similarly, photo-cyclodehydrogenation of 17 did not yield 2 but 19. - The new helical aromatic systems present in 18 and 19 are discussed on the basis of spectroscopic results.
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  • 61
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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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  • 62
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    Liebigs Annalen 1983 (1983), S. 8-12 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 2 Substituted 2-PyrrolidonesThe preparation of the 2-pyrrolidone derivatives 6a, b via β-formyldicarboxylates 4a, b _ starting from 1a, b and 2a, b _ is described; reaction of 4a and 4b in ethanol in the presence of ammonium carbonate gave 5a and 6a, b, respectively. 6a was separated by chromatography into the isomers 7 and 8, 5a is also obtained by reaction of 4a in ethanol in the presence of p-toluenesulfonic acid; 5a in ethanol in the presence of ammonium carbonate at room temperature remained unchanged after 3 days.
    Notes: Die Darstellung der 2-Pyrrolidonderivate 6a, b über die β-Formyldicarbonsäure-diester 4a, b wird beschrieben _ ausgehend von 1a bzw. 1b und 2a bzw. 2b; mehrtägiges Stehenlassen von 4a oder 4b führt in Ethanol in Gegenwart von Ammoniumcarbonat zu 5a sowie zu 6a, b, wobei 5b nicht isoliert worden ist. 6a kann in die Isomeren 7 und 8 getrennt werden. 5a entsteht auch bei der Reaktion von 4a mit Ethanol in Gegenwart von p-Toluolsulfonsäure, welches sich nach 3tägigem Stehenlassen bei Raumtemperatur in Ethanol in Anwesenheit von Ammoniumcarbonat nicht verändert.
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  • 63
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    Liebigs Annalen 1983 (1983), S. 18-23 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of 3,4,4-Trichloro-3-butennitrile with Thiolates and AminesThe reactions of the title compound 2 with thiolates and amines start with a prototropic rearrangement to 4, followed by nucleophilic substitutions of chlorine to give the Z compounds 5 and 8, respectively, which completely or partly rearrange to yield the more stable E isomers 6 and 9, respectively. In the case of pentachlorothiophenolate, however, the Z isomer 5b is stable, probably due to steric reasons.
    Notes: Die Reaktionen der Titelverbindung 2 mit Thiolaten und Aminen beginnen mit der prototropen Umlagerung zu 4. Durch nucleophile Substitution von Chlor entstehen daraus die Z-Verbindungen 5 bzw. 8, die sich im weiteren Verlauf vollständig oder teilweise in die stabilen E-Isomeren 6 bzw. 9 umlagern. Das mit Pentachlorthiophenolat erhaltene Z-Isomere 5b ist wahrscheinlich aus sterischen Gründen stabil.
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  • 64
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    Liebigs Annalen 1983 (1983), S. 107-111 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Chemistry of the Amino Oximes, XVI. The Properties of 2-Pyrimidone N-Oxide DerivativesBy reaction of anti-β-amino ketoximes 1a-d with phosgene, 2-pyrimidone N-oxide derivatives 2a-d are formed as intermediates which react in different ways. By tautomerisation of 2a the 3,6-dihydro-3-hydroxy-2(1H-pyrimidinone derivative 3a and by addition of water to 2b the 3,4,5,6-tetrahydro-3,4-dihydroxy-2(1H)-pyrimidinone 3b is formed. 1,3-Dipolar cycloaddition of the 2-pyrimidone N-oxide 2c to the tautomeric ene-hydroxylamine 3c yields the spiro compound 4. By [3 + 3] cycloaddition of the N-oxide 2d the pentacyclic ring system 6 is formed
    Notes: Aus den anti-β-Amino-ketoximen 1a-d entstehen mit Phosgen intermediär die 2-Pyrimidon-N-oxid-Derivate 2a-d, die unterschiedlich weiterreagieren. Durch Tautomerie bildet sich aus 2a das 3,6-Dihydro-3-hydroxy-2(1H)-pyrimidinon 3a, durch Addition von Wasser an 2b das 3,4,5,6-Tetrahydro-3,4-dihydroxy-2(1H)-pyrimidinon 3b. Aus dem 2-Pyrimidon-N-oxid 2c und seinem tautomeren En-hydroxylamin 3c entsteht durch [3+2]-Cycloaddition die Spiroverbindung 4 und aus dem N-Oxid 2d durch [3+3]-Cycloaddition das pentacyclische System 6.
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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: Synthesis, characterization and stereochemistry of Bridged Intramolecularly alkylated Cobaloximes; monomeric and Dimeric complexes of different configurationLigands have been synthesized containing two vicinaldioxime functions joined by a carbon chain to which is attached in the centre a bromomethyl or chloromethyl group (20, 22, 25). These ligands, upon reaction with cobalt(II) chloride in the presence of pyridine and sodium borohydride afforded bridged intramolecularly alkylated cobaloximes. When the vicinal dioxime functions are separated by a chain of nine carbon atoms mainly dimeric complexes are formed. Two of these, 26, and 27, were isolated and characterized by spectroscopic methods and their structures were established by X-ray crystallography. Ligands containing eleven or thirteen carbon atoms between the dioxime functions afforded mainly monomeric cobaloximes with cis configuration, e. g. 28. The trans-monomeric complex 30 was produced along with the cis isomer when the number of carbon atoms in the bridge was raised to fifteen.
    Notes: Liganden werden synthetisiert, in denen zwei vicinale Dioximfunktionen durch eine Kohlenwasserstoffkette, die in der Mitte eine Brommethyl-oder Chlormethylgruppe trägt, verbunden sind (20, 22, 25). Umsetzung dieser Liganden mit Cobalt(II)-chlorid in Gegenwart von Pyridin und Natriumboranat ergibt überbrückte, intramolekular alkylierte Cobaloxime. Wenn die Dioxim-funktionen durch neun C-Atome getrennt sind, entstehen hauptsächlich dimere Produkte, von denen zwei Diastereomere, 26 und 27, isoliert und sowohl spektroskopisch als auch durch Röntgenstrukturanalyse charakterisiert wurden. Bei elf oder dreizehn C-Atomen zwischen den Dioximfunktionen entstehen hauptsächlich monomere Cobaloxime mit cis-Konfiguration, wie 28 Das trans-Monomere 30 entsteht (neben dem cis-Monomeren) erst, wenn die Anzahl der C-Atome in der Brücke af fünfzehn erhöht wird.
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  • 66
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Wasserstoffentwicklung aus Viologen-Radikalen und aus photochemisch reduzierten Zinn(IV) Porphyrinen in Gegenwart von Kolloidalem PlatinDie Stöchiometrie der platinkatalysierten Reaktion von zwei Methylviologen-Radikalkationen mit zwei Protonen zu zwei Methylviologen-Dikationen und einem Molekül Wasserstoff wird belegt. - Wasserlösliche Zinn(IV)-Porphyrine werden mittels EDTA und sichtbarem Licht über Chlorine zu Isobakteriochlorinen reduziert. In Gegenwart von kolloidalem Platin bleibt die Isobakteriochlorin-Bildung aus, und molekularer Wasserstoff wird gebildet. Der Umsatz beträgt etwa 25 Mol Wasserstoff pro Mol Porphyrin und Stunde. Isobakteriochlorine werden in Gegenwart von Platin unter Luft oder Argon zu Chlorinen dehydriert
    Notes: The stoichiometry of the platinum-catalyzed reaction of two methylviologen radical cations and two protons yielding two methylviologen dications and one molecule of hydrogen is demonstrated. -Watersoluble tin(IV) porphyrins are reduced by EDTA and visible light, first to give chlorins, then isobacteriochlorins. No isobacteriochlorin is formed in the presence of colloidal platinum, but hydrogen is produced. The conversion is about 25 moles of hydrogen per mole of porphyrin and hour. Isobacteriochlorins are dehydrogenated to give chlorins in the presence of colloidal platinum. The reaction takes place either in the air or under argon.
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  • 67
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    Liebigs Annalen 1983 (1983), S. 274-278 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von N-Cyandithiocarbimidic acid Acid DerivativesThe nucleophilic dithiocarbonimidic acid derivatives 2a _ e and the isothiourea 2f react with the α-D-glucopyranosyl bromide 1 to yield the corresponding esters 3a _ f (cf. Scheme 1). 2a gives with the 3-hexenopyranos-2-ulosyl chloride 4 the ester 5b. Bis(bromomethyl)quinoxaline (8) yields with 2a _ c the esters 10a _ c (cf. Scheme 2). The reaction of the dipotassium salt 6 with 4 provides di-O-benzoylkojic acid (7), and with 8 the cyclic N-cyanodithiocarbonimidate 9 is obtained
    Notes: Die nucleophilen Dithiocarbimidsäure-Derivate 2a _ e sowie der Isothioharnstoff-Abkömmling 2f reagieren gemäß Schema 1 mit dem α-D-Glucopyranosylbromid 1 zu den Estern 3a _ f. Verbindung 2a liefert mit dem 3-Hexenopyranos-2-ulosylchlorid 4 den Ester 5b. Bis(brommethyl)chinoxalin (8) ergibt mit 2a _ c gemäß Schema 2 die Ester 10a _ c. Das Dikaliumsalz 6 liefert mit 4 Di-O-benzoylkojisäure (7) und mit 8 den cyclischen N-Cyandithiocarbimidsäure-diester 9.
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  • 68
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    Liebigs Annalen 1983 (1983), S. 220-225 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of the Lycopodium-Alkaloids rac-α-Obscurin through 1,3-Anullation of an EnimineAcid catalysed 1,3-annulation of 1,2,3,4-tetrahydro-6-methyl-2-oxopyridine (1) to the enimine 3, followed by methylation, provides a new regio and stereoselective route to rac-α-obscurine (5). Reduction of rac-N-demethyl-α-obscurine with LiAlH4 yields rac-lycodine (11) and rac-deacetyl-flabellidine (9). A new pathway for the biogenesis of the β-amino-imine 9 is suggested.
    Notes: Die säurekatalysierte 1,3-Anellierung von 1,2,3,4-Tetrahydro-6-methyl-2-oxopyridin (1) an das Enimin 3 liefert nach anschließender Methylierung regio- und stereoselektiv rac-α-Obscurin (5). Reduktion von rac-N-Desmethyl-α-obscurin (4) mit Lithiumaluminiumhydrid führt zur Bildung von rac-Lycodin (11) und rac-Desacetylflabellidin (9). Für das β-Amino-Imin 9 wird ein neuer Biogeneseweg vorgeschlagen.
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  • 69
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    Liebigs Annalen 1983 (1983), S. 261-266 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Substituent Dependence in the synthesis of 2-Oxazolidinones from Phenyloxiranes, 2In the reaction with urea, the trans configurated glycidic esters 4a _ d yield the predominantly new 5-aryl-2-oxooxazolidin-4-carboxylates 5 and 4-aryl-2-oxooxazolidin-5-carboxylates 6. 4,5-cis5b, 4,5-cis 6b, 4,5-cis 6c, and 4,5-trans 6d have been isolated in pure form, the other compounds a _ c paired as mixtures. The structures and the configurations of the components are deduced from the 1H NMR spectra. In general, the carboxylate group influences the formation of the oxazolidinones much more than the phenyl substitent
    Notes: Die trans-konfigurierten Glycidester 4a-d ergeben bei der Reaktion mit Harnstoff in Dimethyl-formamid die zum größten Teil neuen 5-Aryl-2-oxooxazolidin-4-carbonsäureester 5 und 4-Aryl-2-oxooxazolidin-5-carbonsäureester 6.4,5-cis-5b4,5-cis-6b und 4,5-cis-6c Sowie 4,5-trans-6d werden in reiner Form, die restlichen Verbindungen a-c paarig als Gemische isoliert. Die Strukturen und die Konfigurationen der Komponenten werden aus den 1H-NMR-Spektren abgeleitet. Allgemein beeinflußt die Carbonsäureestergruppe die Oxazolidinonbildung stärker als der Phenylrest.
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  • 70
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep, Reversible Redox Systems, XXXII. - Pyridyl-substituted Cyclobutane Derivatives: Syntheses and Redox Reactions of Cyanines, Cyclobutenes, and their Ring Opening ProductsBis(pyridinio)cyclobutanes 1 and 3 are transformed by air oxidation in basic media to give the blue cyanines 2 and 4. Methylation of 4 yields the cyanine 6 which also results from oxidative deprotonation of tetrakis(pyridinio)cyclobutane 5. In solutions of sodium ethanolate the cyanine 6 equilibrates with the “squaric acid” derivative 14. Protonation of 6 produces the cyclobutene cis-13 which changes into trans-13 on base catalysis. Electrocyclic ring opening transforms cis-13 stereoselectively into the butadiene Z,E-15 (t1/2 ≈ 75 min, 60°C, DMSO) and tans-13 into Z,Z-15 (t1/2 ≈ 6h, 30°C, DMSO). Finally, the most stable isomer E,E-15 is formed from Z,Z-15 by redox catalysis. - The cyanines 4, 6 and 14 are electrochemically reversibly reduced in two steps, but undergo only one-electron oxidations. The cyanine 13 is a typical two-step redox system, comparable to its open-chain analogue 16. The butadienes Z,Z-15 and E,E-15 represent other examples of very rare four-step redox systems. The effect of pyridinium groups on the redox properties of 4, 6, and 13-15 is discussed.
    Notes: Die Bis(pyridinium)cyclobutane 1 und 3 gehen im basischen Medium durch Luftoxidation in die blauen Cyanine 2 und 4 über. Methylierung von 4 führt zum Cyanin 6, das sich auch aus dem Tetrakis(pyridinium)cyclobutan 5 durch oxidative Deprotonierung bildet. 6 steht in einer Natriumethanolat-Lösung mit dem “Quadratsäurederivat” 14 im Gleichgewicht. Durch Protonierung entsteht aus 6 das Cyclobuten cis-13, das basenkatalysiert in trans-13 übergeht. Elektrocyclische Ringöffnung verwandelt stereoselektiv cis-13 in das Butadien Z,E-15 (t1/2 ≈ 75 min, 60°C, DMSO) und trans-13 in Z,Z-15 (t1/2 ≈ 6 h, 30°C, DMSO). Unter Redoxkatalyse entsteht aus Z,Z-15 schließlich das stabilste Isomere E,E-15. - Die Cyanine 4, 6 und 14 sind elektrochemisch zweistufig reversibel reduzierbar, aber nur einstufig oxidierbar. 13 ist ein typisches zweistufiges Redoxsystem, vergleichbar mit seinem offenkettigen Analogen 16. Die Butadiene Z,Z-15 und E,E-15 stellen weitere Beispiele für die seltenen vierstufigen Redoxsysteme dar. Der Einfluß der Pyridiniumgruppen auf das Redoxverhalten von 4, 6 und 13-15 wird diskutiert.
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    Liebigs Annalen 1983 (1983), S. 668-677 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Determination of the Absolute Configuration of the Medial (1R,1′S,2S)- and of the Distal (S,S)-1, 1′-Dimethyl-2,2′-spirobiindanThe medial (1R,1′S,2S)- (1b) and the distal (S,S)-1,1′-Dimethyl-2,2′-spirobiindan (1c) have been synthesized with more than 96% optical purity. Their absolute configurations have been determined by that of the starting material, (S)-3-phenylbutyric acid, and by the synthetic pathway. The synthesis bases on the trans alkylation of 3 yielding 4a and b and by the separation of the diacetates 6b and c by preparative HPLC. Together with 1a, which is already described, 1b and c will be used to test the theory of hyperchirality.
    Notes: Das mediale (1R,1′S,2S)- (1b) und das distale (S,S)-1,1′-Dimethyl-2,2′spirobiindan (1c) werden enantiomerenrein (e.e. 〉 96%) dargestellt. Ihre absoluten Konfigurationen sind durch die der Ausgangssubstanz (S)-3-Phenylbuttersäure und den Syntheseweg eindeutig bestimmt. Die Synthese basiert auf der trans-Alkylierung von 3 zu 4a und b und der Trennung der Diacetate 6b und c durch präparative HPLC. Gemeinsam mit dem bereits beschriebenen 1a sollen 1b und c einen Test der Theorie der Hyperchiralität erlauben.
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    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Resolution, Crystal Structure, and Histamine-like Activity of 4-[1-(2-Aminoethylthio)ethyl]-5-methylimidazoleThe resolution of racemic 4-[1-(2-aminoethylthio)ethyl]-5-methylimidazole (1) using optically active Di-O-(P-toluoyl)tartaric acid as well as the histamine-like activity of the enantiomers are described. The crystal structure of (+)-1 · 2HCl · H2O has been determined and refined until R = 0.0483. Accordingly, (+)-1 is R configurated. Only (S)-(-)-1 possesses H1-agonistic activity.
    Notes: Es wird die Racemattrennung von 4-[1-(2-Aminoethylthio)ethyl]-5-methylimidazol (1) mittels optisch aktiver Di-O-(p-toluoyl)weinsäure sowie die histaminartige Wirksamkeit der Enantiomeren beschrieben. Von (+)-1 · 2HCl · H2O wurde die Kristallstruktur bestimmt und bis zu einem R-Wert von 0.0483 verfeinert. Danach ist (+)-1 R-konfiguriert. Von den beiden Enantiomeren besitzt nur (S)-(-)-1 H1-agonistische Aktivität.
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    Liebigs Annalen 1983 (1983), S. 705-711 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 17-Pivalate Derivatives of PregnaneThe sterically hindered hydroxy group at C-17 of pregnane derivatives can be esterified by pivalic anhydride/4-(dimethylamino)pyridine only in the presence of an acetoxy group at C-21. Starting from 4c, the synthesis of corticosteroid 6 can be achieved via 5c by application of this method. However, the 21-deoxypivalate 2e can be obtained only by intramolecular transesterification of 1d to yield 2b, followed by mesylation, and reduction of the corresponding bromide 2d. Further transformation of 2e into the 6α-methyl compound 8 proceeds by transfer hydrogenation and isomerization of the intermediate 6-methylene steroid 7.
    Notes: Die sterisch gehinderte 17-Hydroxygruppe in Pregnanen läßt sich nur in Gegenwart einer 21-Acetoxygruppe mit Pivalinsäureanhydrid/4-(Dimethylamino)pyridin verestern. Nach dieser Methode wird aus 4c über 5c das Corticosteroid 6 synthetisiert. Dagegen kann das 21-Desoxy-17-pivalat 2e nur auf Umwegen aus dem 21-Pivalat 1d über das Umlagerungsprodukt 2b, das Mesylat 2c und das 21-Bromid 2d hergestellt werden. Die weitere Überführung in das 6α-Methylderivat 8 erfolgt über das 6-Methylensteroid 7.
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    Liebigs Annalen 1983 (1983), S. 717-719 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,1-Diphenyl-2-azaallenium Ions as IntermediatesUnder elimination of trimethylamine and formation of 1,1-diphenyl-2-azaallenium ion intermediates 2d from [(diphenylmethylene)aminomethyl]trimethylammonium iodide (5) on heating with sodium methanolate the N-(diphenylmethylene)methoxymethylamine (6) is obtained. With sodium methanethiolate the N-(diphenylmethylene)methylthiomethylamine (7), with sodium cyanide the [(diphenylmethylene)amino]acetonitrile (8) are formed.
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  • 75
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    Liebigs Annalen 1983 (1983) 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 76
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    Liebigs Annalen 1983 (1983), S. 761-769 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Säurekatalysierte Umlagerungen von LinalooloxidBei Behandlung von Linalooloxid (1) mit Säuren entstehen als Umlagerungsprodukte mehrere aliphatische Dienone und/oder alicyclische Enone. Ein möglicher Mechanismus wird diskutiert.
    Notes: Reaction of linalool oxide (1) with acids leads to a variety of dehydration products which are shown to be aliphatic dienones and/or monocyclic enones. A mechanism is proposed to account for the generation of all these compounds.
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    Liebigs Annalen 1983 (1983), S. 770-801 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Neutral Ligands with Surfactant-Type Structure - Synthesis, Complexation, and Ion TransferNew lipophilic neutral ligands which combine crown ether and podand characteristics with structural features of surfactants (cf. formulas 1-12, 16-26) were synthesized. Their complexation behaviour was studied, their solid-to-liquid and liquid-to-liquid phase transfer properties as well as their efficiency in ion transport across a liquid model membrane. Crystalline stoichiometric complexes of the cycles 2a-4a and of 3e with NaSCN, Ba(SCN)2, and Bal2 can be isolated. Among the noncyclic representatives a crystalline complex is obtained only from 11 with Bal2. The ligand 8d behaves in aqueous solution as a typical surfactant showing micelle formation and cloud point.
    Notes: Neue Tensid-verwandte, lipophile Neutralliganden vom Kronenether- und Podandtyp (s. Formeln 1-12, 16-26) wurden synthetisiert. Ihre Komplexierungseigenschaften, ihr fest/flüssig- sowie flüssig/flüssig-Phasentransfervermögen für Ionen und ihre Wirksamkeit beim Ionentransport durch eine flüssige Modellmembran wurden untersucht. Von den Cyclen 2a-4a und 3e sind kristalline stöchiometrische NaSCN-, Ba(SCN)2- und Bal2-Komplexe isolierbar. Unter den offenkettigen Tensidliganden konnte nur von 11 ein Komplex mit Bal2 erhalten werden. Der Ligand 8d zeigt in Wasser Tensidcharakter mit Micellbildung und Trübungspunkt.
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    Liebigs Annalen 1983 (1983), S. 844-851 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Fused Naphthalene Systems from Thebaine, 1Tetrasubstituted naphthalenes 4, prepared by degradation of thebaine, are starting materials for the synthesis of heterocycles with structural elements of pharmacological relevance. “Acetalisation” of 4a leads to the naphtho[1,8-bc]pyran 7a, the course of formation of which has been elucidated.
    Notes: Die durch mehrstufigen Abbau aus Thebain zugänglichen tetrasubstituierten Naphthaline 4 sind Edukte für Heterocyclen mit pharmakophoren Strukturelementen. “Acetalisierung” von 4a führt zum Naphtho[1,8-bc]pyran 7a, dessen Bildungsweise geklärt wurde.
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    Liebigs Annalen 1983 (1983), S. 684-686 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Eine neue Studie zur Darstellung von 3,4-Dihydroxy-1-benzolethanolDie zwei bekannten Darstellungsmethoden der Titelverbindung 1 sind erneut untersucht worden. Danach entsteht in einem Fall ein Gemisch von 1 und 4-[2-(Acetoxy)ethyl]-1,2-benzoldiol (5), im anderen nur 2-Methoxy-4-(2-phenylethyl)phenol (6). Im folgenden wird eine eindeutige und einfache Synthese für 1 durch Reduktion von 3,4-Dihydroxy-1-benzolessigsäure (8) mit LiAlH4 beschrieben.
    Notes: A reinvestigation of the two known methods of preparation of the title compound 1 revealed that one of these leads to a mixture of 1 and 4-[2-(acetoxy)ethyl]-1,2-benzenediol (5). The other method yields only 2-methoxy-4-(2-phenylethyl)phenol (6). An unambiguous straightforward preparation of 1 by LiAlH4 reduction of 3,4-dihydroxy-1-benzeneacetic acid (8) is described.
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    Topics: Chemistry and Pharmacology
    Notes: A One-step Synthesis of 17-Acetoxy-6-methyl-4,6-pregnadiene-3,20-dione (Megestrol Acetate) from 17-Acetoxy-4-pregnene-3,20-dioneStarting from 17-Acetoxy-4-pregnene-3,20-dione (3), a one-step synthesis of megestrol acetate (5) is described.
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    Liebigs Annalen 1983 (1983), S. 714-716 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyacetylenic Compounds, 266. - New C17 Acetylenic Compounds from Solidugo spathulata DCThe roots of Solidago spathulata afforded two C17 acetylenic compounds biogenitically closely related to those from S. virgaurea.
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    Liebigs Annalen 1983 (1983), S. 835-843 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isolation, 13C NMR Spectra, and Biosynthesis of Resistomycin and Resistoflavin from Streptomyces griseoflavus B 71 (Actinomycetales)From the mycelium of Steptomyces griseoflavus B 71 (Actinomycetales) resistomycin (1), resistoflavin (2), and 2-pyrrolecarboxylic acid (3) were isolated. 13C NMR spectra of 1 and 2 were recorded and assigned using long-range C,H coupling and H/D exchange. Feeding experiments with [1-13C]- and [1,2-13C]-acetate confirm biosynthesis from a decaketide precursor 4a folded in an S-shaped loop.
    Notes: Aus dem Mycel von Streptomyces griseoflavus B 71 (Actinomycetales) konnten Resistomycin (1), Resistoflavin (2) und 2-Pyrrolcarbonsäure (3) isoliert werden. Von 1 und 2 wurden die 13C-NMR-Spektren aufgenommen und mit Hilfe weitreichender C,H-Kopplungen und H/D-Austausch interpretiert. Nach Fütterungsexperimenten mit [1-13C]- und [1,2-13C]-Acetat geht 1 aus einem S-förmig gefalteten Decaketid 4a hervor.
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    Liebigs Annalen 1983 (1983), S. 852-859 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pteridines, LXXIII. - Reactivity of Lumazine 5- and 8-Oxides and 5,8-DioxidesThe N-oxide functions in the lumazine system exert various effects on reactivity, whereby the N-8 oxide group is chemically relatively stable and encounters mainly steric hindrance on position N-1. Therefore, methylations proceed with lumazine 8-oxides (1, 3) and 5,8-dioxides (15) only at N-3 to yield 2, 4, and 16, respectively. The N-5 oxide grouping is apt to various functionalisation reactions forming the rearranged 6-chloro- (11, 18), 6-acetoxy- (10, 17), and 6-hydroxylumazines in good yields. 3-Methyllumazine derivatives (7, 9) react with hydrazine to give 3-aminolumazines 12. The new compounds have been characterized by UV, NMR, and mass spectra.
    Notes: Die N-Oxid-Funktionen im Lumazin-System üben unterschiedliche Effekte auf das Reaktionsverhalten aus, wobei sich die N-8-Oxid-Gruppe chemisch als recht stabil erweist, sterisch jedoch die N-1-Position stark behindert. Methylierungen an Lumazin-8-oxiden (1, 3) und -5,8-dioxiden (15) erfolgen daher nur an N-3 (→2, 4 bzw. 16). Die N-5-Oxidgruppierung ist Funktionalisierungsreaktionen leicht zugänglich, so daß Umlagerungen zu 6-Chlor-(11, 18), 6-Acetoxy-(10, 17) und 6-Hydroxylumazinen (13) mit guten Ausbeuten verlaufen. 3-Methyllumazin-Derivate (7, 9) reagieren mit Hydrazin unter Bildung von 3-Aminolumazinen 12. Die neuen Verbindungen werden durch UV-, NMR- und Massen-Spektren charakterisiert.
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    Liebigs Annalen 1983 (1983), S. 890-893 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthese von neuen terpenoiden Tetrahydrofuran- und TetrahydropyranderivatenAusgehend von (+)-α-Pinen, (+)-Limonen und (+)-Car-3-en wurden (3S)-(+)-2,2-Dimethyl-3-(3-oxobutyl)tetrahydrofuran (3a), (3R)-(-)-2,2-Dimethyl-3-(3-oxobutyl)tetrahydrofuran (3b) und (3R)-(+)-2,2-Dimethyl-3(2-oxopropyl)tetrahydropyran (6) synthetisiert.
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    Liebigs Annalen 1983 (1983), S. 885-889 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyacetylenic Compounds, 267. - Biogenetically Interesting Acetylenic Compounds from Cineraria saxifraga DCWhile Cineraria aspera afforded only the typical known constitutents of this genus, C. saxifraga contains in addition to dihydrocinalyratyl acetate and isoelimicin the three C13-acetylenic compounds 3, 6, and 7 which are important intermediates in the biogenesis of polyacetylenes. The structures were elucidated by spectroscopic methods.
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    Liebigs Annalen 1983 (1983), S. 876-884 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2′-Deoxytubercidin - Synthesis of a 2-Deoxyadenosine Isoster by Phase-Transfer Glycosylation2′-Deoxytubercidin (1), an isoster of 2′-deoxyadenosine (2), has been synthesized omitting naturally occurring synthons via phase-transfer glycosylation of the chromophore 3a with the toluoyl-protected halogenose 6. The glycosylation reaction produces the β-anomer exclusively. Alkaline hydrolysis of the protecting groups of 5a yields 2′-deoxy-2-(methylthio)tubercidin (5b). Desulfurization with Raney nickel catalyst gives 2′-deoxytubercidin (1). The position of glycosylation has been determined by 13C NMR spectroscopy using the long-range coupling constant between C-6 and 1′-H and was found to be N-7.
    Notes: 2′-Desoxytubercidin (1), ein Isoster des 2′-Desoxyadenosins (2), wurde durch Phasentransfer-glycosylierung des Chromophors 3a mit der toluoylgeschützten Halogenose 6 unter Umgehung natürlicher Vorstufen dargestellt. Bei der Glycosylierung entsteht nur das β-Anomer. Nach alkalischer Hydrolyse der Schutzgruppen von 5a wird 2′-Desoxy-2-(methylthio)tubercidin (5b) erhalten, das nach Entschwefeln mit Raney-Nickel die Titelverbindung 1 ergibt. Die Glycosylierungsposition N-7 konnte mit Hilfe der 13C, 1H-NMR-Fernkopplung zwischen C-6 und 1′-H festgelegt werden.
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    Liebigs Annalen 1983 (1983), S. 913-921 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of (1S)-(-)-FrontalinThe aggregation pheromone 1 of the southern pine beetle Dendroctonus frontalis has been synthesized in high optical yield starting from (2R)-2-methyl-2-epoxy-1-propanol (4) which is obtained from methallyl alcohol (3) via enantioselective epoxidation according according to Sharpless9).
    Notes: Das Aggretationspheromon 1 des Borkenkäfers Dendroctonus frontalis wird in hoher optischer Reinheit ausgehend von (2R)-2-Methyl-2-epoxy-1-propanol (4) synthetisiert. 4 wird durch enantioselektive Epoxidierung von Methallylalkohol (3) analog der von Sharpless9) beschriebenen Methode erhalten.
    Additional Material: 1 Tab.
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  • 88
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 931-938 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naphthylenedi(heteroarenes), II. - Synthesis and Spectroscopic Properties of 2,2′-NaphthylenedibenzoxazolesStarting from 2,2′-(1,4-naphthylene)dibenzoxazole1) used as fluorescent whitening agent for polyester fibers and plastics it is systematically investigated how structural modifications affect spectroscopic properties such as absorption, fluorescence, extinction and quantum yield. Nine of the ten possible positionisomeric 2,2′-naphthylenedibenzoles and some of their substituted derivatives were prepared and the spectral data measured; only the 1,8-isomers remain unknown until now.
    Notes: Ausgehend von dem als optischer Aufheller für Polyesterfasern und Kunststoffe verwendeten 2,2′-(1,4-Naphthylen)dibenzoxazol1) wird systematisch untersucht, wie sich Strukturabwandlungen auf spektroskopische Eigenschaften, wie die Lage der Absorptions- und Fluoreszenzbande, die Oszillatorstärke und Quantenausbeute auswirken. Von den zehn möglichen stellungsisomeren 2,2′-Naphtylendibenzoxazolen sind bisher neun und einige ihrer Substitutionsprodukete synthetisiert und gemessen worden; lediglich von den 1,8-Isomeren ist noch keine Verbindung bekannt.
    Additional Material: 2 Tab.
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  • 89
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1230-1236 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermal Rearrangements and Nucleophilic Ring cleavage of cis-2,3-Dihydro-2,3-Diphenyl-1H-1,4-diazepinesThermolysis of cis-2,3-dihydro-2,3-diphenyl-1H-1,4-diazepine (c2a) at 150°C in [D5]bromobenzene solution affords quantitatively 2,3-diphenylpyridine (4a) via ring contraction and loss of one mole of ammonia. In striking contrast, on heating a [D5]bromobenzene solution of cis-2,3-dihydro-2,3,6-triphenyl-1H-1,4-diazepine (c2b) to 140°C loss of C7H8 occurs resulting in the formation of 2,5-diphenylpyrimidine (5b) in 70% yield. Mechanisms are proposed in order to rationalize these surprising ring contractions. Piperdine in methanol cleaved the ring of c2a ·H⊕ producing meso-1,2-diphenyl-1,2-ethanediamine (12) and 1,3-dipiperidinopropenylium perchlorate (13).
    Notes: Die Thermolyse von cis-2,3-Dihydro-2,3-diphenyl-1H-1,4-diazepin (c2a) bei 150°C in [D5]Brombenzol ergibt unter Ringkontraktion und Abspaltung von ammoniak quantitativ 2,3-Diphenylpyridin (4a). Dagegen entsteht aus cis-2,3-Dihydro-2,3,6-triphenyl-1H-1,4-diazepin (c2b) bei 140°C in [D5]Brombenzol unter Verlust von C7H8 2,5-Diphenylpyrimidin (5b) in 70% Ausbeute. Für diese überraschenden Ringkontraktionen werden Mechanismen vorgeschlagen. Durch Piperidin in Methanol wird c2a ·H⊕ in meso-1,2-Diphenyl-1,2-ethandiamin (12) und 1,3-Dipiperidinopropenylium-perchlorat (13) gespalten.
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  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1257-1266 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Steiractinolides from Aspilia and Wedelia SpeciesThe reinvestigation of the polar fractions of Aspilia parvifolia afforded eight further steiractinolides and one geranylgeraniol derivative. The aerial parts of a new Wedelia species gave three derivatives of 4,5-dihydrosteiractinolides. The structures were elucidated by detailed 1H NMR studies. The configurations of some eudesmanolides from Wedelia trilobata were corrected and the absolute configuration of the steiractinolides has been determined by using the Horeau method.
    Notes: Die erneute Untersuchung der polaren Fraktionen von Aspilia parvifolia ergibt acht weitere Steiractinolide und ein Geranylgeraniol-Derivat. Die oberirdischen Teile einer neuen Wedelia-Art liefern drei Derivate von 4,5-Dihydrosteiractinolid. Die Strukturen werden durch eingehende 1H-NMR-Untersuchungen geklärt. Die Konfigurationen einiger Eudesmanolide aus Wedelia trilobata werden korrigiert, und die absolute Konfiguration der Steiractinolide wird mit Hilfe der Horeau-Methode bestimmt.
    Additional Material: 4 Tab.
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  • 91
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1249-1256 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosylimidates, 8. - Synthesis of 1-ThioglycosidesAs expected. the reactive acetyl-protected O-(α-D-glucopyranosyl) trichloroacetimidate 3 reacts with S-nucleophiles and trifluoroborane-ether as catalyst to yield exclusively 1-thio-β-D-glucopyranosides with inversion of the configuration. The corresponding benzyl-protected α-trichloroacetimidate 4 affords with retention of the configuration alkyl 1-thio-α-D-glucopyranosides. The importance of alkyl 1-thio-β-D-galactopyranosides in enzyme induction was reason to apply this convenient and efficient glycosyl-transfer reaction to the synthesis of isopropyl 1-thio-β-D-galactopyranoside (12a) and the sodium salt of 1-thio-β-D-galactopyranose (12b), respectively.
    Notes: Das reaktive acetylgeschützte O-(α-D-Glucopyransyl)trichloracetimidat 3 liefert mit S-Nucleophilen unter Bortrifluorid-Ether-Katalyse erwartungsgemäß unter Inversion der Konfiguration ausschließlich 1-Thio-β-D-glucopyranoside. Mit dem entsprechenden benzylgeschützten α-Trichloracetimidat 4 werden unter Retention der Konfiguration ausschließlich 1-Thio-α-D-glucopyranoside erhalten. Die Bedeutung von Alkyl-1-thio-β-D-galactopyranosiden zur Enzyminduktion war Anlaß, diese einfache Glycosylübertragung auch zur Synthese von Isopropyl-1-thio-β-D-galactopyranosid (12a) und des Natriumsalzes von 1-Thio-β-D-galactopyranose (12b) anzuwenden.
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  • 92
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Alkaloiden des Reserpin-Typs, I. - Ein weg zur Darstellung von tetracyclischen Schlüssel-SynthesevorstufenDie Schlüssel-Synthesevorstufen von Typ 2, die zum Aufbau von Alkaloiden des Reserpin-Typs dienen, wurden auf verschiedenen Wegen hergestellt.
    Notes: Key intermediates of type 2 serving the synthesis of reserpine-type alkaloids were prepared in different routes.
    Additional Material: 1 Tab.
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  • 93
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbohydrates Containing the 2,6-Dioxabicyclo[3.3.0]octane Skeleton: 3,6-Anhydrohexofuranose Derivatives with D-gluco, D-manno, L-ido, and L-gulo ConfigurationAll possible 3,6-anhydrofuranoses as well as their triacetates, methyl glycosides, and methyl diacetylglycosides have been prepared, some of them for the first time. This allowed an analysis of the equilibria of the anomers of the free sugars in water and of the anomeric composition of methyl glycosides. 1H NMR spectra of these and other related derivatives showed the clear preference of conformations with quasi-axial orientation of the substituent at C-1. 13C NMR spectra and optical rotations are also discussed.
    Notes: Es wurden alle möglichen 3,6-Anhydrofuranosen sowie deren Triacetate, Methylglycoside und deren Diacetate z. T. erstmalig synthetisiert. Dies ermöglichte eine genaue Analyse der Anomerengleichgewichte sowohl der freien Verbindungen in wäßriger Lösung als auch bei deren Umsetzung zu den Methylglycosiden. Die 1H-NMR-spektroskopische Untersuchung der vorgenannten sowie weiterer Derivate ergab eine eindeutige Bevorzugung von Konformationen, in denen der Substituent an C-1 eine quasi-axiale Orientierung einnimmt. Darüberhinaus werden die 13C-NMR-spektren und die optischen Rotationen diskutiert.
    Additional Material: 8 Tab.
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1332-1344 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Selective Tosylations of 3,6-Anhydrohexofuranosides with gluco, manno, and gulo ConfigurationSelective monotosylation of methyl 3,6-anhydro-α-D-mannofuranoside (1a) preferentially yields the 5-O-tosylate 1e which opens via nucleophilic substitution access to β-L-gulo derivatives 2 by inversion of configuration at C-5. Analogously reaction of the ditosylate 1b with potassium acetate in dimethylformamide gives L-gulo compounds exclusively. Substitution at C-2 is not observed. Contrary to this, the β-manno derivative 3a is selectively tosylated at 2-position to give 3c which is transformed only after very long reaction times into the gluco series by nucleophilic substitution. Desired conversion of β-manno compounds 3 into α-L-gulo derivatives 4 is achieved only via the ditosylate 3b which is preferentially substituted by inversion of configuration at position 5 yielding 4c. Further insight into the different behaviour of 1a and 3a was gained by equal monotosylation of 2a, 5a, and 6a with β-L-gulo and β- and α-D-gluco configuration, respectively. The obtained results are rationalized by considering steric as well as polar effects.
    Notes: Selektive Monotosylierung von Methyl-3,6-anhydro-α-D-mannofuranosid (1a) ergibt bevorzugt das 5-O-Tosylat 1e, das durch nucleophile Substitution unter Inversion an C-5 den Zugang zu den Derivaten 2 mit β-L-gulo-Konfiguration erlaubt. Auch die Umsetzung des Ditosylates 1b mit Kaliumacetat in Dimethylformamid führt ausschließlich in die L-gulo-Reihe. Eine Substitution an C-2 wird nicht beobachtet. Das β-manno-Derivat 3a hingegen wird bevorzugt in 2-Stellung zu 3c tosyliert, das nur bei extrem langen Reaktionszeiten durch nucleophile Substitution in die gluco-Reihe übergeführt werden kann. Die erwünschte Überführung auch der β-manno-Derivate 3 in die α-L-gulo-Reihe 4 gelingt über das Ditosylat 3b, das bevorzugt in 5-Stellung unter Inversion der Konfiguration zu 4c substituiert werden kann. Zum besseren Verständnis der unterschiedlichen Selektivitäten bei 1a und 3a wurde auch die Monotosylierung von 2a, 5a und 6a mit β-L-gulo-sowie β- und α-D-gluco-Konfiguration untersucht. Die Ergebnisse werden unter Berücksichtigung sterischer und polarer Faktoren interpretiert.
    Additional Material: 1 Ill.
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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: Syntheses of peptide Alkaloids, VII. - Amino Acids and Peptides, XXXVIII. - Total Synthesis of the 10, 11-Dihydrozizyphines A and BThe 10,11-dihydrozizyphines A (13a) and B (15a) were synthesized. The cyclopeptide ring closure reactions were accomplished by catalytic hydrogenation of the linear ω-amino acid pentafluorophenyl ester 8a.
    Notes: Die 10,11-Dihydrozizyphine A (13a) und B (15a) wurden synthetisiert. Der Cyclopeptidringschluß wurde durch katalytische Hydrierung des linearen ω-Z-Aminosäure-pentafluorphenylesters 8a erreicht.
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1496-1503 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of 2,3,4,4-Tetrachloro-3-butenamides with Alcoholates and AminesFrom the amides 2c-e, available from hexachlorobutadiene (1a) via the intemediates 1b, 2a and 2b, the thermally unstable allenes 3 are generated by bases. On treating 2c at room temperature with one mole of ethylate a dimer of 3c, probably 4, and from 2d with four moles of methylate the addition product 6 is obtained. Reactions of 2c-e with primary amines lead to the enamines 7 and 8, respectively. Secondary amines however, yield the nonconjugated compounds 9 which rearrange with an excess of amines into the conjugated isomers 10. Spectroscopic evidence for 1:1 equilibriums of the stereoisomers 7⇆8 and 10⇆12 in CDCl3 solution is given.
    Notes: Aus den Amiden 2c-e, die aus Hexachlorbutadien (1a) über 1b, 2a und 2b leicht zugänglich sind, werden die thermisch instabilen Allene 3 durch Basen erzeugt. Aus 2c entsteht bei Raumtemperatur mit einem Mol Ethylat ein Dimeres von 3c, wahrscheinlich 4, und aus 2d mit vier Molen Methylat das Additionsprodukt 6. Die Reaktionen von 2c-e mit primären Aminen führen zu den Enaminen 7 bzw. 8. Sekundäre Amine liefern statt dessen die nicht konjugierten Verbindungen 9, die sich mit einem Aminüberschuß in die konjugierten Isomeren 10 umlagern. Spektroskopisch lassen sich in CDCl3 1:1-Gleichgewichte zwischen den Stereoisomeren 7⇆8 und 10⇆12 nachweisen.
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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: Synthese von Alkaloiden des Reserpin-Typs, II. - Synthese von 18-Hydroxyyohimbin-Stereoisomeren und Raunescin-Derivaten mit normalem MolekülgerüstAusgehend von dem in der vorausgehenden Mitteilung beschriebenen Ketoester 2 wurden drei Raunescin-Derivate (7c, 9c, 10c) und ein Isoraunescin-Stereoisomer (10d) - alle mit normalem Yohimbangerüst - synthetisiert.
    Notes: Starting from the previously described keto ester 2, three raunescine analogues (7c, 9c, 10c) and one isoraunescine stereoisomer (10d) - all with a normal yohimbane skeleton - have been synthesized.
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  • 98
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Alkaloiden des Reserpin-Typs, III. - Synthese von rac-deserpidin und einem rac-Raunescin-EpimerAusgehend von der in der vorausgehenden Mitteilung beschriebenen, zur Darstellung von Yohimbanen mit normalem Molekülgerüst verwendeten Schlüssel-Synthesevorstufe 2, wurden rac-Deserpidin (1b) und das rac-Raunescin-Epimer 9c mit epi-allo- bzw. allo-Gerüst hergestellt. Im Laufe der Synthese wurden einige Stereoisomere des in Position 18 substituierten allo-Yohimbins hergestellt und auf spektroskopischem und chemischem Wege charakterisiert.
    Notes: Starting from the key intermediate 2 previously used for the preparation of derivatives with a normal yohimbane skeleton, the synthesis of rac-deserpidine (1b) and the rac-raunescine epimer 9c, having an epi-allo and allo skeleton, respectively, has been performed. In the course of the synthesis several stereoisomers of C-18-substituted allo-yohimbine have been prepared and characterized by spectroscopic and chemical means.
    Additional Material: 3 Tab.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), 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: Conformation of (E)-1,3,4,5-Tetra-O-acetyl-2,6-anhydro-D-arabino-hex-1-enitol in the Crystalline StateThe title compound 3, a pyranose derivative containing an exocyclic double bond, adopts in the crystalline state as well as in solution 5C2(D) conformation. Substituents at C-3 and C-4 are thus axial positioned. This was verified by X-ray analysis of 3 (R = 0.055 and Rw = 0.025 for 1791 reflexions).
    Notes: Die Titelverbindung 3, ein Pyranosederivat mit exocyclischer Doppelbindung, liegt im Kristall ebenso wie in Lösung in einer 5C2(D)-Konformation vor. Die Substituenten an C-3 und C-4 nehmen hierbei eine axiale Position ein. Dies ergab die Röntgenstrukturanalyse von 3, die bis zu einem R-Wert von 0.055 (gewichtet: 0.025) für 1791 Reflexe verfeinert werden konnte.
    Additional Material: 1 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1374-1392 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Synthesis of 8-Amino-5-aza-1,3-nonamdiene DerivativesStarting from glycine derivatives and the diazepines 1, 8-succinimido-5-aza-1,3-nonamdienes 5 and 8-phthalimido-5-aza-1,3-nonamidienes 8 are synthesized stereospecifically in trans configuration. Cleavage of the side-chain leads in particular to the unstable 8-amino-5-aza-1,3-nonamdiene derivative 11b which, after N-acylation, yields the crystalline N-acylamino-β-lactams 12-15. The nicotinic acid derivatives 17 and 26 provide after several steps, the last one being a photo-induced ring expansion, the diazepine pairs 19/20 and 27/28. These diazepines react with ketene derivatives to give stereospecifically by cycloaddition the trans β-lactams 21/23 and 29/30. Cleavage of the CH2CH2-SiMe3 protective groups of the adducts 21 and 23 using tetra-n-butylammonium fluoride causes unexpectedly cleavage of the benzoyl group and migration of the double bond yielding the enimines 24 and 25
    Notes: Ausgehend von Glycinderivaten und den Diazepinen 1 werden die 8-Succinimido-5-aza-1,3-nonamdiene 5 und die 8-Phthalimido-5-aza-1,3-nonamdiene 8 stereospezifisch mit trans-Konfiguration hergestellt. Durch Abbau der Seitenkette gelangt man speziell zu dem instabilen trans-8-Amino-5-aza-1,3-nonamdienderivat 11b, das durch N-Acylierung die kristallinen N-Acylamino-β-lactame 12-15 liefert. Aus Nicotinsäurederivaten 17 und 26 werden die Diazepinpaare 19/20 und 27/28 als Gemische in einem photochemischen Prozeß hergestellt. Diese Diazepine ergeben durch Cycloadditionsreaktionen mit Ketenderivaten auf stereospezifische Weise die trans-β-Lactame 21/23 und 29/30. Bei der Abspaltung der CH2CH2-SiMe3-Schutzgruppe aus den Addukten 21 und 23 mit Tetra-n-butylammonium-fluorid tritt unerwartet Abspaltung der Benzoylgruppe auf, wobei unter Doppelbindungswanderung die Enimine 24 und 25 enstehen.
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