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  • 1
    Electronic Resource
    Electronic Resource
    Aziridines, 66 [1]. Arene Hydrides. 12 [2]. Reactions of carbanions with two sterically demanding 1-benzoylaziridines: SET, SN2, carbonyl attackDedicated to Prof. Hans Möhrle on the occasion of his 65th birthday (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 269-273 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 2-phenyl (1a) and 2-benzyl (1b) 1-benzoyl-2-butylaziridines with carbanions X-, AH-, and Fl- of xanthene, dihydroanthracene and fluorene always form N-(2-butylethyl)-benzamides carrying phenyl (9a) or benzyl (9b). This reductive ring opening indicates an SET mechanism with aziridino ketyls 6a, b as intermediates. Nucleophilic ring opening (SNs) is found only with the carbanion of the lowest reducing power: Fl- → 5a, b (62%, 14%). These two mechanisms cleave different bonds, a finding without precedence in SN2/SET competitions. Carbonyl addition resulting in benzoyl transfer to xanthene, dihydroanthracene or fluorene is usually also observed. It is the main reaction with X- and 1a. The highest yields of 9a, b are obtained with AH- since a special inner-sphere SET is available.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19953370157
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  • 2
    Electronic Resource
    Electronic Resource
    Eliminative Cleavage of a N-Phenylsulfonyl-2-iminopyrrolidine by naphthalenide yields the respective N-propylbenzenesulfonamide (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 611-612 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360710
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  • 3
    Electronic Resource
    Electronic Resource
    Comment on the Estimation of the Dimerisation Constant of Caffeine (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2161-2163 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reasons for the low reliability of the Compare e.g. former results cited in [3][4] with our results in [3].H-NMR estimation of the dimerisation constant of caffeine in D2O are discussed. The main reasons are (1) strong influence of small variations in the monomer shifts δ0 which are to be determined by extrapolation, and (2) disturbance by the formation of higher oligomers. The dilemma ist that attempts to minimize errors from (1) increase the influence of (2) and vice versa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670816
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  • 4
    Electronic Resource
    Electronic Resource
    Aminoäthylierung mit Aziridinverbindungen, V. Über die Darstellung von Aminoäthylmalonestern mit sekundärer Amino-Gruppe (1968)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 716 (1968), S. 121-126 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Durch Umsetzung von Aziridin-Basen des Typs 1 mit überschüssigem Malonester in siedendem Benzol bei Zusatz von Lithiumhydrid und Lithiumjodid können β-Aminoäthyl-malonsäure-diäthylester (2) mit einer sekundären Amino-Gruppe erhalten werden, wenn die Aziridin-Base N-tert.-Butyl- oder o-Tolyl-substituiert ist. Ein Cyclohexyl-Rest genügt nicht, um den entsprechenden Aminoäthyl-malonsäurediäthylester vor dem Lactam-Ringschluß zum Pyrrolidon 4 zu schützen. Aus β-tert.-Butylaminoäthyl-malonsäurediäthylester (2a) wurde mit Hydrazinhydrat 4-[β-tert.-Butylaminoäthyl]-pyrazolidin-dion-(3.5) (6) erhalten, das als Zwitter-Ion vorliegt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19687160117
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  • 5
    Electronic Resource
    Electronic Resource
    Notiz über die Protonierung von Coffein (1970)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 731 (1970), S. 174-175 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Note on the Protonation of CaffeineThe signals of the imidazole part of caffeine are shifted farther downfield than are the other signals on going from CH3CO2H to HClO4/CH3CO2H. At the same time coupling between 7-CH3 and 8-H increases. Both effects are consistent with a protonation at 9-N.
    Notes: Die NMR-Signale des Imidazol-Teils vom Coffein werden beim Übergang von CH3CO2H zu HClO4/CH3CO2H als Lösungsmittel stärker paramagnetisch verschoben als die anderen Signale. Gleichzeitig vergrößert sich die Kopplung zwischen 7-CH3 und 8-H. Beides steht im Einklang mit einer Protonierung am 9-N.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19707310120
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  • 6
    Electronic Resource
    Electronic Resource
    Arene Hydrides, 10 Michael Additions of Anthracene Hydride. Selective Reduction of the ArC=C Moiety by Fragmentation of the Michael Adduct (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 99-102 
    Details
    ISSN: 0170-2041
    Keywords: Cinnamic acid derivatives, selective saturation ; Michael addition ; Anthracene hydride ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Anthracene hydride (AH-) in THF undergoes Michael addition onto the acrylic acid derivatives 1 and 2. Secondary reactions of the first formed anions 3 and 4 of the Michael adducts depend on the absence (3) or presence (4) of an aryl group in β position. The non-benzylic 3 or its protonated or deprotonated form can cyclize via ester condensation to yield the “dibenzo-bicyclo[3.2.2.]nonanones” 10b, c. Deprotonation of the anion 4 by excess AH- usually leads to fragmentation of the C—CAr bond formed in the Michael addition. The overall result is a selective C = C reduction of cinnamonic acid derivatives and analogues: PhR′C = C → PhR′CH — CH. This fragmentation is hampered in the Michael addition adduct 4h with dimethyl benzylidenemalonate 2h probably due to the necessity of a pronounced conformational reorganization during the fragmentation step.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199219920120
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  • 7
    Electronic Resource
    Electronic Resource
    Nitrone, II. 2.3.4-Substituierte Isoxazolidinone-(5) aus Aldonitronen und CH-aciden Verbindungen (1971)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 748 (1971), S. 143-153 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nitrones, II1). 2,3,4-Substituted 5-Isoxazolidinones from Aldonitrones and CH-Acidic CompoundsDialkyl malonates and C-aryl-N-methylnitrones 1 as well as 3,4-dihydroisoquinoline N-oxide in presence of sodium alkoxide yield the alkyl 5-isoxazolidinone-4-carboxylates 4,6, and 7; the compounds 4 are exclusively trans-substituted with exception of 4c. Malonic acid diamide reacts in the same way to give the corresponding 5-isoxazolidinone-4-carboxamide 8. C-Styryl-N-methylnitrone and dimethyl malonate yield a mixture in which the corresponding isoxazolidinone 5 is spectroscopically recognized. Analogously, ethyl acetoacetate gives the corresponding trans-substituted 4-acetylisoxazolidinone derivative 9. Under aprotic conditions, even methyl phenylacetate reacts with a nitrone furnishing the 3,4-diaryl substituted isoxazolidinone 10.
    Notes: C-Aryl-N-methyl-nitrone 1 sowie 3.4-Dihydro-isochinolin-N-oxid ergeben mit Malonsäurediestern und Natriumalkoxid die Isoxazolidinon-(5)-carbonsäure-(4)-ester 4,6 und 7. Die Verbindungen 4 sind, mit Ausnahme von 4c, im Isoxazolidinon-Ring ausschließlich trans-substituiert. Analog reagiert Malonsäurediamid unter Bildung des entsprechenden Isoxazolidinon-(5)-carbonsäure-(4)-amids 8. C-Styryl-N-methyl-nitron liefert mit Malonsäuredimethylester ein Gemisch, in dem das Isoxazolidinon 5 spektroskopisch zu erkennen ist. Acetessigester gibt entsprechend das ebenfalls trans-substituierte 4-Acetyl-isoxazolidinon-Derivat 9. Unter aprotischen Bedingungen reagiert auch Phenylessigester mit einem Nitron, wobei das 3.4-Diaryl-substituierte Isoxazolidinon 10 entsteht.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19717480116
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  • 8
    Electronic Resource
    Electronic Resource
    Nitrone, III. Die Reformatzky-Reaktion bei Nitronen (1971)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 749 (1971), S. 146-152 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nitrones, III. The Reformatzky Reaction with NitronesThe Reformatzky reaction may be applied to nitrones as carbonyl analogues when tetrahydrofuran is used as solvent and the reaction temperature is controlled. The N-methyl-C-aryl-aldonitrones 1 react with zinc and the ethyl α-bromo-alkanecarboxylates 2 to yield the corresponding 2-methyl-3-aryl-5-isoxazolidinones carrying 0, 1 or 2 methyl groups in position 4 depending on the ester used. Analogously 3,4-dihydroisoquinoline-N-oxide (5) is converted to the unstable compound 6. m- and p-Nitro-benzaldehyde-N-methylnitrone do not react. Those nitrone substituents which increase the electronic charge at the nitrone O-atom favor HBr elimination as competing reaction which completely dominates in the case of p-dimethylaminobenzaldehyde-N-methylnitrone. The 2,4-dimethyl-3-aryl-5-isoxazolidinones (4d, e) are obtained as mixtures of the geometrical isomers.
    Notes: Die Reformatzky-Reaktion läßt sich in Tetrahydrofuran als Lösungsmittel bei geeigneter Temperaturführung auf die Carbonyl-analogen Nitrone übertragen. Mit Hilfe von Zink und α-Brom-alkancarbonsäureestern 2 erhält man aus den N-Methyl-C-aryl-aldonitronen 1 die 2-Methyl-3-aryl-isoxazolidinone-(5) 4, welche je nach verwendetem Ester in 4-Stellung 0, 1 oder 2 Methylgruppen tragen. Analog reagiert 3.4-Dihydro-isochinolin-N-oxid (5) zur instabilen Verbindung 6. m- und p-Nitro-benzaldehyd-N-methyl-nitron setzen sich nicht um. Substituenten, welche die Elektronendichte am Nitron-O-Atom erhöhen, begünstigen als Konkurrenzreaktion die HBr-Eliminierung, die im Falle des p-Dimethylamino-benzaldehyd-N-methyl-nitrons die Reformatzky-Reaktion völlig zurückdrängt. Die 2.4-Dimethyl-3-arylisoxazolidinone-(5) (4d, e) werden als cis/trans-Isomerengemische erhalten.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19717490116
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