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  • Articles  (19)
  • Wiley-Blackwell  (19)
  • BioMed Central
  • 1990-1994  (19)
  • 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
    Photochemical and Thermal Rearrangement of Acyl-Substituted Quinone Methides, Accessible by Dimethyldioxirane Oxidation of Benzofurans and Subsequent Valence Isomerization of the Resulting Epoxides (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2697-2699 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2-methyl-3-phenyl ; Benzofuran epoxides ; Quinone methides ; (Z/E) Photoisomerization ; Norcaradiene ; Benzocycloheptafuran ; Thermal rearrangement ; Xanthenes, 9-acetyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photoisomerization of quinone methides 3 to benzocycloheptafuran 4 and the thermolysis of the latter to xanthenes 5 are reported. The quinone methides 3 are accessible by dimethyldioxirane oxidation and subsequent valence isomerization of the resulting benzofuran epoxides 2. On irradiation (λ 〉 400 nm), the quinone methides 3 rearrange by cyclization to the corresponding norcaradiene, and ring enlargement affords the benzocycloheptafurans 4. Thermolysis of the cycloheptatrienes 4 leads to the xanthenes 5, first by cycloreversion to the norcaradienes, followed by electrocyclization to the chromenes and tautomerization of the latter. The new cycloheptatrienes 4 and xanthenes 5 were fully characterized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261220
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal and Photochemical Rearrangement of 3-Substituted 2-Methylbenzofuran Epoxides and Their Valence-Isomeric Quinone Methides (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 433-436 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2-methyl- ; Benzofuran epoxides ; Quinone methides ; Photoisomerization ; Chromenes ; 3-Benzofuranones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimethyldioxirane oxidation of the 3-substituted 2-methylbenzofurans 1 [1a: 3(E)-styryl, 1b: 3-acetoxy, 1c: 3-(tert-butyldimethylsilyloxy)] is reported. Only quinone methide 3a, none of the benzofuran epoxides 2a-c, could be detected by 1H- and 13C-NMR spectroscopy at low temperature (-30°C), which on photoisomerization led to chromene 7a. The benzofuran-3-ones 5b, c and the α-diketone 6c are presumably formed by thermal isomerization of the transient benzofuran epoxides 2b, c and quinone methide 3c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270220
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  • 7
    Electronic Resource
    Electronic Resource
    Epoxidation of 2,3-Dimethylbenzofurans by Dimethyldioxirane (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 231-234 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl ; Benzofurans, 2,3-dimethyl- ; Benzofuran epoxides ; Quinone methides ; Methanol addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of epoxides 2 by the reaction of the chloro- and methyl-substituted 2,3-dimethylbenzofurans 1 with dimethyl-dioxirane at low temperature is reported. These labile epoxides were spectroscopically characterized (1H and 13C NMR) at subambient temperatures. Epoxidation of benzofuran 1c affords a 31:69 mixture of epoxide 2c and quinone methide 3c, the latter presumably being produced by valence isomerization of the epoxide. On warming up above -10°C, the epoxides 2 suffer decomposition. Treatment of epoxide 21 with methanol yields the tautomeric mixture of adducts 4i and 4i′.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250136
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  • 8
    Electronic Resource
    Electronic Resource
    Ring Cleavage of Benzofurans and Tetrahydrobenzofurans by m-Chloroperbenzoic Acid Epoxidation (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 941-946 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Benzofuran ; Benzofuran epoxide ; Quinone methide ; Benzofuran-2-one ; 2,4-Cyclohexadien-1-one, spiroepoxide ; cis-Ene dione ; Perester, β-hydroxy- ; 1,3-Benzodioxole ; Keto enol ester ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of the benzofurans 1a-f (tetrahydrobenzofurans 1g, h) with excess m-CPBA is reported. The in situ generated, highly reactive benzofuran epoxides 2a-f and their quinone methides 3a-f (cis-ene diones 3g, h) afford the labile tautomeric peroxy esters 5 and 5′ by nucleophilic addition of the peroxy acid. On elimination of m-chlorobenzoic acid, the peroxy esters 5/5′ of the benzofuran derivatives 1a-f rearrange thermally to the keto esters 6 by C—C cleavage or to the spiro epoxides 7 by C—O cleavage. The latter undergo thermal isomerization to the 1,3-benzodioxoles 8 and Diels-Alder cycloaddition to the corresponding dimers 9. Independently, the keto esters 6 and the 1,3-dioxoles 8 were synthesized by thermolysis of the dioxetanes 11. The tautomeric m-CPBA adducts 5/5′ of the persistent ene diones 3g, h, derived from the tetrahydrobenzofuran derivatives 1g, h, rearrange as well to the spiro epoxides 7g, h. In contrast to the benzofuran derivatives 6a-f, the keto enol ester 6h suffers Baeyer-Villiger rearrangement with another molecule of m-CPBA to form the ene diester 10h.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270523
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of 2H-Benzoxetes by Photoinduced [2 + 2] Cycloaddition of Quinone Methides, Accessible by Dimethyldioxirane (DMD) Oxidation of 2,3-Dimethylbenzofurans (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1115-1118 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2,3-dimethyl- ; Benzofuran epoxides ; Quinone methides ; [2 + 2] Photocycloaddition ; Benzoxetes ; Hetero-Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation (λ 〉 366 nm) of the quinone methides 3, which were formed by valence isomerization of the methyl-, chloro-, and tert-butyl-substituted 2,3-dimethylbenzofuran epoxides 2, afforded the novel 2H-benzoxetes 4 by photochemical [2 + 2] cycloaddition. These strained and highly labile benzoxetes 4 were spectrally (1H and 13C NMR) characterized at subambient temperatures. On prolonged storage (2-3 d) at -20 to -10°C, the benzoxetes 4 reverted to the quinone methides 3 and/or benzofuran epoxides 2.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270622
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  • 10
    Electronic Resource
    Electronic Resource
    HPLC-Meßtechnik auf dem Weg zur kontinuierlichen Prozeßkontrolle (1992)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 823-823 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330640978
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