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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of (-)-Streptenol A, (±)-Streptenol B, C and D (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 2135-2140 
    Details
    ISSN: 0947-3440
    Keywords: Streptenols ; Chiral building block ; Polyketides ; Dienones ; Secondary metabolites ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-(2,2-Dimethyl-1,3-dioxan-4-yl)acetaldehyde (3) was used for the preparation of streptenol A and B (Scheme 1) via a Grignard reaction with 1-bromopent-3-ene. Hereby optically pure (4′R)-3 gave the antipode of Streptenol A. Reaction with lithiated 1-pentyne opened access to streptenol C and D. To obtain the dienone structure of streptenol C and D, a palladium-catalyzed alkynone isomerization was induced. Kinetic differences in the acid-mediated cleavage of the 1,3-acetonide protected 1,3,5-triol system caused the stereoselectivity in the natural products. So only the (3S*,5R*) acetonide of streptenol B reacted under mild hydrolytic conditions and gave after transacetalization first a 3,5-protected streptenol B with pure relative stereochemistry and finally (3S*,5R*)-streptenol B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961228
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  • 2
    Electronic Resource
    Electronic Resource
    Olefin Cross-Metathesis with Monosubstituted Olefins (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 441-444 
    Details
    ISSN: 0947-6539
    Keywords: alkenes ; allylsilanes ; C-C coupling ; cross-metathesis ; jasmonates ; molybdenum ; ruthenium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The applicability of olefin cross-metathesis for the synthesis of different unsymmetrically substituted functionalized olefins is described. The coupling of different functionalized olefins in the presence of Grubbs' ruthenium catalyst or Schrock's molybdenum catalyst afforded the crossed products in good yields and with very high selectivities. Derivatives of jasmonic acid and functionalized allylsilanes were prepared by this catalytic method for carbon-carbon double bond formation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030316
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  • 3
    Electronic Resource
    Electronic Resource
    Radical Cation Initiated Cycloaddition Reactions Between 2-Vinylindoles and β-Substituted Enaminonitriles (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 447-452 
    Details
    ISSN: 0947-6539
    Keywords: cycloadditions ; domino reactions ; electrochemistry ; electron transfer ; radical ions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron transfer initiated cycloaddition reactions between 2-vinylindoles, acting as heterodienes, and β-substituted enaminonitriles lead to different cycloaddition products depending on the substituents. Initiated by potentiostatically controlled electrolysis, an anellation of a cyclopropanated five-membered ring system to the diene yielding cyclopropapyrrolo[1,2-a]indoles can be achieved in just one reaction step. Interestingly, the formation of a cyclopropane ring system takes place in reaction mechanisms which involve radicals and radical cations. In addition to these products, [4 + 2]-cycloaddition products with subsequent [1,4] dialkylamino shifts can also be formed. The formation of both products can be attributed to new reaction pathways via radical cation intermediates.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030317
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  • 4
    Electronic Resource
    Electronic Resource
    Additionen an die Dreifachbindung, XX. Polycyclische Thiophenderivate durch Hetero-Cope-Umlagerung (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 368-373 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Additions to the Triple Bond, XX. Polycyclic Thiophene Derivatives via Hetero-Cope RearrangementThe adduct of N-allyl-thiophenamines is transformed into various tricyclic thiophene derivatives via Hetero-Cope rearrangement.
    Notes: Das Addukt von N-Allyl-thiophenaminen an Acetylendicarbonester kann durch Hetero-Cope-Umlagerung in diverse tricyclische Thiophenderivate übergeführt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060140
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  • 5
    Electronic Resource
    Electronic Resource
    Additionen an die Dreifachbindung, XIX. Tricyclische Heteroaromaten durch sigmatrope Umlagerung (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 355-367 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Additions to the Triple Bond, XIX. Tricyclic Heteroaromatic Compounds via Sigmatropic RearrangementQuinolones 4 obtained via hetero-Cope rearrangement of N-allylmaleic ester derivatives yield tricyclic hetero aromatic compounds either via attack at the quinolone moiety or at the ester group, depending on reaction conditions.
    Notes: Die durch Hetero-Cope-Umlagerung von N-Allyl-maleinester-Derivaten zugänglichen Chinolone 4 können je nach Wahl der Bedingungen entweder über Beteiligung der Chinolon-Gruppierung oder der Estergruppe in verschiedenartige tricyclische Heterocyclen über-geführt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060139
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  • 6
    Electronic Resource
    Electronic Resource
    Eine flexible und regioselektive Acronycin-Synthese (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 439-450 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Flexible and Regioselective Acronycine SynthesisA regioselective synthesis of acronycine (1) is reported which, owing to the constitution of the intermediates, should open routes to its metabolites.
    Notes: Es wird eine regioselektive Synthese des Acronycins (1) mitgeteilt, die über Zwischenstufen verläuft, deren Konstitution auch Wege zu den Acronycin-Metaboliten eröffnen sollte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781110204
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  • 7
    Electronic Resource
    Electronic Resource
    Isolierung und Synthese des 5-Ethyl-2-methyl-11H-pyrido[3,4-a]-carbazolium-hydroxids, ein neuer Indolalkaloidtyp aus Aspidosperma gilbertii (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3245-3248 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isolation and Synthesis of 5-Ethyl-2-methyl-11H-pyrido[3,4-a]carbazolium Hydroxide, a New Indole Alkaloid Type from Aspidosperma gilbertiiSmall quantities (1.5 mg) of a new indole alkaloid type 5 have been isolated from the bark of Aspidosperma gilbertii. A short, efficient synthesis of the natural product is presented, thus making it available on a gram scale.
    Notes: Aus der Rinde von Aspidosperma gilbertii konnten geringe Mengen (1.5 mg) eines neuen Indolalkaloid-Typs 5 isoliert werden. Durch eine kurze und effiziente Synthese ist der Naturstoff in Grammengen leicht erhältlich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801131012
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  • 8
    Electronic Resource
    Electronic Resource
    Stereoselektive Synthesen von Taxan-Derivaten (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 101-109 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Synthesis of Taxane DerivativesSubstituted racemic 4,8,12-trinortaxanes were prepared stereoselectively in several steps from the dienone 10. A variant of the de Mayo reaction with bicyclononenones 4 and cyclohexen produced the desired configuration at C(8) of the taxane framework. Retro-aldol cleavage of the tetracycle 5 led to the taxane skeleton 6. Stereoselective reduction followed by treatment with base afforded 7b. Hydrolysis of the acetal group and further reduction yielded 9 in which the relative configuration corresponds to the one of the natural products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720113
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  • 9
    Electronic Resource
    Electronic Resource
    Hetero-Cope-Umlagerungen, III Vinylindole durch Hetero-Cope-Umlagerung (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 673-682 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hetero-Cope Rearrangements, III. - Vinylindoles via Hetero-Cope RearrangementThe reaction of N-phenylnitrones 1 with allenes 2 which are substituted with electron acceptor groups gives various products via addition and [3,3] sigmatropic rearrangements depending on the specific acceptor group. In this manner one obtains 2-substituted indoles 8a, 8b, and 10 from propadienyl trichloromethyl sulfoxide. Using phenyl propadienyl sulfone a derivative 4a of tetrahydro-1-benzazepin-4-one is obtained. Reactions with allenecarbonitril proceed via several steps and yield 2-vinylindoles of type 6. Intermediate products could not be isolated.
    Notes: Die Reaktion von N-Phenylnitronen 1 mit acceptorsubstituierten Allenen 2 führt via Addition und [3,3]-sigmatrope Umlagerung in Abhängigkeit vom Acceptor zu unterschiedlichen Produkten. So erhält man mit (Propadienyl)(trichlormethyl)sulfoxid 2-substituierte Indole 8a, 8b und 10. Mit (Phenyl)(propadienyl)sulfon wird ein Tetrahydro-1-benzazepin-4-onderivat 4a gebildet. Umsetzungen mit Allencarbonitril liefern über einen Mehrstufenprozeß direkt diverse 2-Vinyl-indole des Typs 6. Zwischenprodukte ließen sich nicht isolieren.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850403
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  • 10
    Electronic Resource
    Electronic Resource
    Cyclisierungen zu 9,11-disubstituierten Acronycin-DerivatenHerrn Prof. Dr. M. Seefelder zum 60. Geburtstag gewidmet. (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 503-511 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclizations to 9,11-Substituted Acronycine DerivativesHerrn Prof. Dr. M. Seefelder zum 60. Geburtstag gewidmet.The following methods for the cyclization of olefinic precursors of acronycine, which give rise to derivatives of this alkaloid 4a substituted in positions 9 and 11, are reported: Lewis acid catalysed olefin aldehyde cyclization and subsequent oxidation converts 1b into 11-hydroxynoracronycine 4e, while 1f and 7a give 9-bromonoracronycine 4c. Base catalyzed cyclization of the oxoester 2 affords the 9,11-dihydroxy derivative 10, while the corresponding oxoaldehyde, obtainable by reduction of the enol lactone 3, gives the 9-hydroxyacridone 12.
    Notes: Es wird über folgende Methoden der Cyclisierung olefinischer Acronycinvorstufen zu 9- und 11-substituierten Derivaten dieses Alkaloids1) 4a berichtet: Lewissäuren-katalysierte Olefin-Aldehyd-Cylisierung führt, ausgehend von 1b, nach Oxidation zu 11-Hydroxynoracronycin 4e; aus 1f und 7a wird 9-Bromnoracronycin 4c erhalten. Basenkatalysierte Cylisierung des Oxoesters 2 ergibt das 9,11-Dihydroxyderivat 10, der durch Readuktion des Enollactons 3 gewinnbare kor-respondierende Oxoaldehyd das 9-Hydroxyacridon 12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800404
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