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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 101 (1968), S. 1770-1782 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die ESR-Spektren der Azomethin-nitroxide 2-6 kann man durch Substitution der Phenylkerne mit tert.-Butylgruppen und gegebenenfalls mit Deuterium entscheidend vereinfachen, so daß eine vollständige Analyse möglich wird. Dabei ergibt sich für die Nitroxide 2 und 3 eine relativ große Spindichte an der Nitroxidgruppe und im benachbarten Phenylkern Ar2 und eine sehr geringe Spindichte am Azomethin-Stickstoff. Demgegenüber ist in den Nitroxiden 4-6 das ungepaarte Elektron in viel stärkerem Maße über das gesamte Molekül delokalisiert. Die Nitroxide 4-6, sollten daher nahezu eben gebaut sein, während in den Nitroxiden 2 und 3 die Molekülteile gegeneinander verdrillt sein müssen, was auf sterische Ursachen zurückgeführt wird.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0947-3440
    Keywords: 3,7-Dioxa-2-azabicyclo[3.3.0]octanes ; 2,6-Dioxa-3-azatricyclo[5.3.1.04.11]undecanes ; Amino alcohols ; Chiral ligands ; Enantioselective catalysis ; Homogenous catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reduction of the enantiomerically pure allyloxy esters 9 or ent-9 with DIBAH afforded the corresponding aldehydes which were treated in situ with chiral or achiral hydroxylamines 8 to give nitrones 10. These underwent a spontaneous intramolecular 1,3-dipolar cycloaddition, affording the bicyclic compounds 11 and 12, respectively. In an analogous manner, a mixture of the tricyclic compounds 14 and 15 was prepared. Treatment of compound 16 with cyclohexene oxide afforded a mixture of diastereomers 17 and 18. Diastereomers 14 and 15 as well as 17 and 18 could be separated by chromatography. X-ray analyses of compounds 11Ff, 17, and 11Af · HCl were performed. The bicyclic and tricyclic compounds were used as chiral ligands in the reaction of diethylzinc with aldehydes 19, in particular with benzaldehyde (19a). Using bicyclic compounds with a tertiary β-hydroxyalkyl substitutent at the N atom as ligands, ee's in the range of 78 to 95% were found. Whereas for the best ligands 11Ae and Af the enantioselectivity in the reaction of 4-tolualdehyde was only slightly decreased, with the aliphatic aldehydes 19c and d distinctly lower enantioselectivities were determined.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1649-1653 
    ISSN: 0947-3440
    Keywords: 9-Oxa-3-thia-10-azatricyclo[6.2.1.04,10]undecanes, 6-heteroatom-substituted ; 3-Thiazoline N-oxides ; Mercaptoacetaldehyde ; 1,3-Dipolar cycloadditions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Alkenal oximes 4, 12, and 13 were prepared by various methods. These oximes undergo a domino reaction with mercaptoacetaldehyde (1-M) affording tricyclic compounds 6, 17 and 18, respectively. At first the mercapto group adds to the oxime function forming a hydroxyamino moiety which then condenses with the aldehyde group giving the cyclic nitrones 10, 15, and 16, resp., as intermediates. These nitrones undergo spontaneously an intramolecular cycloaddition yielding the tricyclic compounds (6, 17, 18). The regioselectivity of the latter reaction step is opposite to that observed for corresponding intermolecular nitrone cycloadditions. The domino reaction proceeds highly selectively affording only one of the diastereomers. Starting from enantiomerically pure oxime 13, we prepared optically active 18. The stereogenic center of 13 induces the formation of three further stereogenic centers in the product. The configuration at C-5 of 18 was determined by a NOESY experiment.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 469-471 
    ISSN: 0947-3440
    Keywords: Cycloadditions ; Asymmetric Synthesis ; Heterocycles ; Alkynes ; Reductions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral nonracemic compound 4 was prepared from ethyl (S)-(-)-lactate and 1,4-dibromo-2-butyne. Reduction with DIBAH at -72°C and subsequent treatment of the resulting dialdehyde with N-methylhydroxylamine yielded the dinitrone 5, which underwent two consecutive intramolecular cycloadditions to give the chiral nonracemic compound 7. The structure of 7 was confirmed by an X-ray analysis. Reductive ring opening afforded compound 8.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 98 (1965), S. 3907-3916 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N.N-Bis-cyanmethyl-aryl- oder -alkylamine (2) lassen sich mit Phthaldialdehyd (1) bzw. Naphthalin-dialdehyd-(2.3) zu Azepin-Derivaten (3) kondensieren. Auch o-Dibenzoyl-benzol (4) gibt mit N.N-Bis-cyanmethyl-isopropylamin ein Azepin-Derivat, mit allen anderen hier untersuchten Bis-cyanmethyl-Verbindungen jedoch ein Kondensationsprodukt (5) aus 2 Moll. o-Dibenzoyl-benzol und 1 Mol. Bis-cyanmethyl-Verbindung. Aus N.N-Bis-cyanmethyl-aminen allein bildet sich in Gegenwart von Kalium-tert.-butylat in tert.-Butylalkohol ein Dimerisierungsprodukt, während Amine, die gleichzeitig die Cyanmethyl- und die Cyanäthylgruppe enthalten, in Pyrrolidin-Derivate (11) übergehen.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 101 (1968), S. 1761-1769 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nach verschiedenen Verfahren werden C-Amino-nitrone 1 B (5, 15) bzw. deren Hydrochloride (9) dargestellt, die sich zu den Nitroxiden 2 (6, 16, 10) oxydieren lassen: α-Anilino-phenylacetonitril (3) ergibt mit Nitrosoverbindungen in Gegenwart von Basen die Amino-nitrone 5. Arylhydroxylamine reagieren mit N-Phenyl-trimethylacetimidchlorid (7) zu den Hydrochloriden 9. Die C-Amino-nitrone 15 werden entweder durch Umsetzung von N-Aryl-form-imidsäure-äthylestern (11) mit Arylhydroxylaminen bzw. tert.-Butylhydroxylamin oder von N-Methylen-aminen (13) mit aromatischen Nitrosoverbindungen gewonnen.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 98 (1965), S. 3902-3906 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die Synthese von bisher unbekannten N-Cyanmethyl- und N.N-Bis-cyanmethyl-Derivaten schwach basischer Arylamine in Eisessiglösung unter Zusatz von wasserfreiem Zinkchlorid aus Arylamin, Paraformaldehyd und Kaliumcyanid wird beschrieben.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 98 (1965), S. 3917-3923 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bei der Umsetzung von Diaryl-acetonitrilen sowie Aryl-arylamino-acetonitrilen mit Nitrosoverbindungen in Gegenwart von Basen bilden sich Nitrone (8). Aus 2.3-Diphenyl-propionitril und Nitrosobenzol entsteht α.α′.N.N′-Tetraphenyldinitron (19). Die Reaktion von 2.3-Diphenyl-bernsteinsäure-dinitril mit Nitrosoverbindungen führt dagegen zu 2-substituierten 5-Imino-3.4-diphenyl-Δ3-isoxazolinen (22).
    Type of Medium: Electronic Resource
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