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  • 1
    Electronic Resource
    Electronic Resource
    Über die Reaktion einiger 2H-Pyran-2-on-Derivate mit primären Aminen (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 407-416 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Some 2H-Pyran-2-one Derivatives with Primary AminesThe versatile reactivity of 6-unsubstituted 2H-pyran-2-ones towards aliphatic and aromatic amines has been studied. It was found that the result of the reaction depends not only on the substitution of 2H-pyran-2-ones and on the structure of amines, but also on the stoichiometric ratio of reacting compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740218
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  • 2
    Electronic Resource
    Electronic Resource
    Eine neue einfache Synthese spirocyclischer 1H-Chinolin-Derivate (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 1274-1280 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New and Simple Method for the Synthesis of Spirocyclic la-QuinolinesThe reaction of anilines with (+)-(R)-pulegone in toluene at temperatures between 125 and 150° with 4-toluenesulfonic acid or I2 as catalysts leads to diastereoisomeric mixtures of spiro[cyclohexane-1,2′(1′H)-quinoline] derivatives (see 1-4, Scheme 1; Table). The diastereoisomers are separated by column chromatography, and the structure of the single isomers is determined by NMR-spectroscopic methods. A reaction mechanism proceeding via several 6π-electrocyclic rearrangements and H-shifts is proposed for the formation of 1H-quinolines 1-4 (Scheme 2). This mechanism is in accordance with the results of the reaction of 2-isopropenylaniline with 3-methylcyclohexanone which leads to a stereoisomeric mixture of 3,4′-dimethylspiro[cyclohexane-1,2′(1H)-quinolines] (Scheme 3).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750428
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  • 3
    Electronic Resource
    Electronic Resource
    Säurekatalysierte Umsetzungen von 2- Vinylanilin-Derivaten mit 1-Benzyl- und 1-Methylpiperidin-4-on: Eine Elegante Synthese Neuer Polycyclischer Indol-Derivate (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1469-1475 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acid-Catalyzed Reactions of 2-Vinylaniline Derivatives with 1-Benzyl- and 1-Methylpiperidin-4-one: An Elegant Synthesis of New Polycyclic Indole DerivativesThe reaction of 2-vinylaniline derivatives with 1-benzylpiperidin-4-one or 1-methylpiperidin-4-one in toluene at temperatures between 115 and 120° with toluene-4-sulfonic acid as catalyst leads in good yields to a new class of polycyclic indole derivatives (Scheme 1, Table 1). The structure of the new diastereoisomerically pure racemic compounds 1-5 is determined by NMR-spectroscopic methods. A reaction mechanism proceeding via cyclization of enamine 9, leading to a racemic, tricyclic reactive intermediate 10, and subsequent intramolecular 1,5-dipolar cyclization as key steps in proposed for the formation of octahydropyrido[4′,3′:4]cyclobut[1,2-b]indoles 1-5. The scope and limitations of the new method are discussed (see Table 2).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760407
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  • 4
    Electronic Resource
    Electronic Resource
    Synthese von einigen 2H-Pyran-2-on-Derivaten (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 883-889 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Synthesis of Some 2H-Pyran-2-one DerivativesDerivatives of 6-unsubstituted 2H-pyran-2-one have been synthesized by several different methods. The 4-chloro-2H-pyran-2-one (9) is the most important, since it serves as starting material for the synthesis of different 4-substituted 2H-pyran-2-ones (Scheme 2). Also described are simple transformations of cumalic-acid derivatives producing 5-(2,2-dichlorovinyl)-2H-pyran-2-one (23), 2-oxo-2H-pyran-2-carbonitrile (26), and 4,5-bis(trifluoromethyl)-2H-pyran-2-one (32) (Scheme 3 and 4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730414
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  • 5
    Electronic Resource
    Electronic Resource
    Eine neue Synthese von Benzo[b]naphtho[2,3-d]thiophenenHerrn Professor Dr. Karl Gewald mit besten Wünschen zum 60. Geburtstag (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 1099-1101 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Synthesis of Benzo[b]naphtho[2,3-d]thiophenes
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320631
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  • 6
    Electronic Resource
    Electronic Resource
    Synthese eines neuen Thienospirans: 6,7-Dihydro-1′-methyl-spiro[benzo[b]thiophen-4(5H),2′-piperidin] (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 995-1003 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a New Thienospiran: 6,7-Dihylro-1′-methyl-spiro[benzo[j]thioxhen-4(5H),2′-piperidine]The title spiro compound 6 - a N-methyl derivative of a new parent system - has been synthesized from nitrile 8 via 4-phenoxybutylation, followed by modified Schmidt degradation, ensuing O-deprotection and final cyclization. The constitution of the target compound and of all intermediates is established by 1H-n.m.r. and 13C-n.m.r.-spectroscopy and by microelementary analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320616
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesen neuer Chinolon-Chemotherapeutika. V [5] Methodische Untersuchungen zur Synthese von Chinoloncarbonsäuren (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 267-279 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Novel Quinolone-Chemotherapeutics. V. Methodical Investigations on the Synthesis of Quinolone Chemotherapeutics.The synthesis of 6, 7-dihalogen-N-ethyl-4-oxo-l, 4-dihydroquinoline-3-carboxylic acids (3a, b) from 3, 4-dihalogen-anilines is a three-step processes: (a) N-ethylation, (b) reaction with ortho formic ester and Meldrum's acid, (c) intramolecular cyclization. An increase of the total yields in comparison with known methods is mainly connected with the third step. Here the Meldrum's method allows reactions in solution at temperatures ≥ 100°C. With application of special Lewis acids the 6, 7-dihalogen-substituted products are formed in relatively high yields (6, 7-difluoro-l-ethyl-4-oxo-1, -4-dihydro-quinoline-3-carboxylic acia (3a): 71%; 7-chloro-6-fluoro-1 -ethyl-4-oxo-1, 4-dihydro quinoline-3-carboxylic acid (3b): 60%) without impurities of the corresponding 5, 6-dihalogen substituted isomers. Anhydrides (5) of 4-oxo-1, 4-dihydro-quinolone-3-carboxylic acids with dibromo and difluoro-boric acid were synthesized and shown to facilitate the aromatic nucleophilic substitution. The kinetics of two reactions (5a → 6 and 3b → 7) were determined and relative reaction rates established.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330211
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  • 8
    Electronic Resource
    Electronic Resource
    Oxidation of 8-Methoxypsoralen (8-MOP) by Dimethyldioxirane. Evidence for the Formation of a Furocoumarin Epoxide by Methanol Trapping, a Potential Mutagenic Agent (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 1095-1096 
    Details
    ISSN: 0170-2041
    Keywords: Furocoumarin ; Dioxirane ; 8-Methoxypsoralen epoxide ; Mutagenicity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 8-methoxypsoralen (1) with dimethyldioxirane in methanol at 25°C yields the methanol adduct 3, namely the 2,3-dihydro-2-hydroxy-3,9-dimethoxy-7H-furo[3,2-g][1]benzopyran-7-one, whose structure was unequivocally assigned by means of spectroscopic data. Methanol adduct 3 is produced by dioxirane epoxidation of the furan double bond of 1 to 2 followed by nucleophilic attack by methanol at the benzylically activated C-3. The direct observation of the 8-methoxypsoralen epoxide (2) was not possible, because at low temperature (below 0°C) dimethyldioxirane does not epoxidize 1, while at 25°C this labile epoxide decomposes. On the basis of these results, a rational explanation is offered as to the origin of the regioisomeric methanol adduct 5, namely 2,3-dihydro-3-hydroxy-2,9-dimethoxy-7H-furo[3,2-g][1]benzopyran-7-one, observed in traces (ca. 0.2%), when 1 is treated with sodium hypochlorite and hydrogen peroxide in aqueous methanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1992199201180
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  • 9
    Electronic Resource
    Electronic Resource
    Dioxirane Oxidation of Furocoumarins and Naphthofurans Preparation of the Psoralen Epoxides (1994)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1994 (1994), S. 689-693 
    Details
    ISSN: 0170-2041
    Keywords: Epoxidation ; Dioxirane, methyl(trifluoromethyl)-, dimethyl- ; Psoralen epoxide ; Naphthofurans ; Quinone methides ; [4 + 2] Cycloaddition ; DNA alkylation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl(trifluoromethyl)dioxirane oxidation of natural psoralen (1a) and 8-methoxypsoralen (8-MOP, 1b) and dimethyldioxirane oxidation of some related 2,3-substituted furocoumarins 1c-e at subambient temperature afforded the corresponding labile epoxides 2a-e. The reaction of acetylated 2,3-dimethylnaphthofurans 1f,g with dimethyldioxirane afforded the corresponding quinone methides 3f, g, derived from the valence-isomeric epoxides 2f,g. Cycloaddition of ethyl vinyl ether to the quinone methides 3b, c led to the benzopyrans 5b, c. In methanol at -50°C, the 8-MOP epoxide (2a) was converted by nucleophilic attack into the corresponding adduct 4b. The latter result demonstrates that the psoralen epoxides may serve as powerful alkylating agents and provides a possible chemical basis for their observed genotoxicity due to adduct formation by nucleophilic attack of DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199419940710
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