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  • 1
    Electronic Resource
    Electronic Resource
    Bicyclic and Tricyclic Compounds with β-Amino Alcohol Groups as Chiral Ligands in the Enantioselective Reaction of Diethylzinc with Aldehydes (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 423-434 
    Details
    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
    URL: http://dx.doi.org/10.1002/jlac.199719970222
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  • 2
    Electronic Resource
    Electronic Resource
    Formation of tricyclic compounds in domino reactions of alkenal oximes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1649-1653 
    Details
    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
    URL: http://dx.doi.org/10.1002/jlac.1995199509229
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  • 3
    Electronic Resource
    Electronic Resource
    An Intramolecular 1,3-Dipolar Cycloaddition Involving One Alkyne and Two Nitrone Groups (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 469-471 
    Details
    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
    URL: http://dx.doi.org/10.1002/jlac.199719970306
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  • 4
    Electronic Resource
    Electronic Resource
    Aminyloxide (Nitroxide), XXX. Vinylaminyloxide. Spindichteverteilung und Reaktionen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2776-2785 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminyl Oxides (Nitroxides), XXX. Vinylaminyl Oxides. Spin Density Distribution and ReactionsVinylaminyl oxides 1a - c and [17O]-1a have been investigated ESR spectroscopically. The spin density distribution of 1a agrees well with a theoretical spin density calculation. Oxidation of 2e does not yield 1e but 4e directly. 1a and c are transformed to secondary radicals 4 by a spin-trap reaction with the starting nitrons 2. Such reactions of 1c have been found also with nitrone 6, nitrile oxide 8, diene 10, and nitroso compounds 12 and 13, yielding the radicals 7, 9, 11, 14, or 15, respectively. 1c dimerises by C  -  C coupling to form 17. Attempts to prepare vinylaminyl oxides by oxidation of 19 or 21 yielded the isomeric pair of iminyl oxides 20A/B and the enaminyl radical 22, respectively.
    Notes: Die Vinylaminyloxide 1a - c sowie [17O]-1a wurden ESR-spektroskopisch untersucht. Die Spindichteverteilung in 1a stimmt gut mit theoretisch berechneten Werten überein. 1a und c wandeln sich durch eine Spin-trap-Reaktion mit Ausgangsnitron 2 in Sekundärradikale 4 um. 2e liefert bei der Oxidation nicht 1e, sondern direkt 4e. Reaktion von 1c mit Nitron 6, Nitriloxid 8, Dien 10 und Nitrosoverbindungen 12 und 13 ergab Radikale 7, 9, 11, 14, oder 15, 1c dimerisiert unter C - C-Verknüpfung zu 17 Versuche zur Darstellung von Vinylaminyloxiden durch Oxidation von 19 führten zu Iminyloxiden 20A/B, aus 21 wurde das Enaminyl-Radikal 22 gebildet.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120803
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  • 5
    Electronic Resource
    Electronic Resource
    Vinylaminyloxide (Vinylnitroxide) mit großer Spindichte in der VinylgruppeAminyloxide, 22. Mitteilung. Diese Arbeit wurde vom Fonds der Chemischen Industrie unterstützt. - 21. Mitteilung: H. G. Aurich u. W. Weiss, Tetrahedron, im Druck.Herrn Professor Karl Dimroth zum 65. Geburtstag gewidmet (1975)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 87 (1975), S. 590-591 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19750871609
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  • 6
    Electronic Resource
    Electronic Resource
    Bildung von Nitronen und anderen Folgeprodukten bei der Umsetzung von N,- Alkyl- und N,- Arylhydroxylaminen mit verschiedenen Acetylenderivaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2769-2775 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Nitrones and other Products in the Reaction of N-Alkyl-and N-Arylhydroxylamines with Various Acetylene DerivativesThe reaction of tert-butylhydroxylamine )(2) with the acetylenic compounds 1a-c afforded the nitrones 3, whereas with 1d the 1:2 adduct 4 and with 1 e the isoxazolone 5 were obtained. In the reaction with aromatic hydroxylamines only the nitrone 9b was isolated, in the other cases secondary products of structure 10 or 11/12 were formed. Dimethyl acetylenedicarboxylate reacts with nitrones 3 to yield 13, with 9b to yield 14b.
    Notes: Tert-Butylhydroxylamin (2) ergibt mit den Acetylenderivaten 1a - c die Nitrone 3, mit 1d das 1:2-Addukt 4 und mit 1e das Isoxazolon 5. Mit aromatischen Hydroxylaminen konnte nur das Nitron 9b isoliert werden, sonst entstanden Folgeprodukte der Konstitution 10 oder 11/12. Acetylendicarbonsäure-dimethylester reagiert mit den Nitronen 3 zu 13, mit 9b zu 14b.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120802
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  • 7
    Electronic Resource
    Electronic Resource
    Aminyloxide (Nitroxide), XX. Bildung von Aminyloxiden bei Reaktionen von Nitriloxiden mit Hydroxylaminen (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 2764-2780 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminyl Oxides (Nitroxides), XX. Formation of Aminyl Oxides in the Reaction of Nitrile Oxides with HydroxylaminesThe nitrile oxides 4 react with hydroxylamines 3 to give N2-hydroxyamidinyl N1-oxides 2. Using N-isopropylhydroxylamine (3C) the corresponding radical 2C was detectable only in one case, secondary radicals 12C being formed by oxidative ring closure. The radicals 12 are also obtained directly by reaction of 4 with oximes 7. The primary radicals 2E-G, being formed from N-arylhydroxylamines 3E-G, are converted into the secondary radicals 15 or 16 by ring formation. In every case 4 acts as oxidizing agent. On the other hand 4 reacts with amines 10 to form the amidoximes 11 in good yields, no radicals being detectable. Oxidation of N-arylamidoximes 11E-H by lead dioxide yields the benzimidazolyl oxides 20.
    Notes: Nitriloxide 4 reagieren mit Hydroxylaminen 3 unter Bildung der N2-Hydroxyamidinyl-N1-oxide 2. Mit N-Isopropylhydroxylamin (3C) läßt sich allerdings nur in einem Fall 2C nachweisen, hier bilden sich durch oxidativen Ringschluß die Folgeradikale 12C, 12 erhält man auch direkt durch Umsetzung von 4 mit Oximen 7. Die aus N-Arylhydroxylaminen 3E-G primär gebildeten Radikale 2E-G wandeln sich unter Ringbildung in die Sekundärradikale 15 oder 16 um. In allen Fällen wirkt 4 in der Reaktionslösung als Dehydrierungsmittel. Setzt man 4 aber mit Aminen 10 um, so sind keine Radikale nachweisbar, man isoliert in guten Ausbeuten die Amidoxime 11. Die N-Arylamidoxime 11E-H gehen bei der Oxidation mit Bleidioxid in die Benzimidazolyloxide 20 über.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751080835
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  • 8
    Electronic Resource
    Electronic Resource
    Photochemie von Oxoindolinylidenamin-N-oxiden (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 200-211 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemistry of Oxoindolinylidenamine N-OxidesIrradiation of the semicyclic amidine N-oxides 1 in benzene or tetrahydrofuran gives the ring extension products 3 and 4, the deoxygenation products 5, and in small yield isatin (6A). The oxaziridine 9 is assumed to be the primary product of the photoreaction. On the other hand irradiation of 1a in methanol yields mainly 8a by ring opening. In the photolysis of the nitrones 2 the tetrahydroquinazoline-2,4-diones 3 and isatin (6a) or N-methylisatin (6b), respectively, are formed as main products in aprotic solvents as well as in methanol. The intermediate oxaziridine 12e which could be isolated in this case, was shown to be converted into 3e and 6b.
    Notes: Bei der Belichtung der semicyclischen Amidin-N-oxide 1 in Benzol oder Tetrahydrofuran bilden sich die Ringerweiterungsprodukte 3 und 4 sowie die Desoxygenierungsprodukte 5 und in geringem Umfang Isatin (6a). Als photochemisches Primärprodukt wird das Oxaziridin 9 angenommen. In Methanol führte die Belichtung von 1a dagegen hauptsächlich zum Ringöffnungsprodukt 8a. Bei der Photolyse der Nitrone 2 entstehen sowohl in aprotischen Lösungsmitteln als auch in Methanol als Hauptprodukte die Tetrahydrochinazolin-2, 4-dione 3 und Isatin 6A bzw. N-Methylisatin 6B. Hier konnte das intermediär gebildete Oxaziridin 12e isoliert und seine Umwandlung in 3e und 6b gezeigt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090119
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  • 9
    Electronic Resource
    Electronic Resource
    Vinylaminyl Oxides (Vinyl Nitroxides) with High Spin Density in the Vinyl GroupAminyl Oxides, Part 22. - This work was supported by the Fonds der Chemischen Industrie. Part 21: H. G. Aurich and W. Weiss, Tetrahedron, in press. (1975)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 14 (1975), S. 551-552 
    Details
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197505511
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  • 10
    Electronic Resource
    Electronic Resource
    Aminyloxide (Nitroxide), XXIII. Verhalten von N-tert-Butyl(3-oxoindolin-2-yliden)amin-N-oxid und N-tert-Butyl(3-oxo-3H-indol-2-yl)aminyl-N-oxid gegenüber Nucleophilen (1976)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1976 (1976), S. 432-439 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminyl Oxides (Nitroxides), XXIII. - Reaction of N-tert-Butyl(3-oxoindolin-2-yliden)amine N-Oxide and N-tert-Butyl(3-oxo-3H-indol-2-yl)aminyl N-Oxide with NucleophilesIn the cyclic amidine N-oxide 1 as well as in its oxidation product 2 the carbonyl group is attacked by nucleophiles. From 1 formamidine N2-oxides 3 are formed by ring-opening, whereas different products result from reaction of 2. Ammonia, secondary amines or hydrogen cyanide yield only addition products 8. With hydroxide ions ring-expansion occurs with formation of 9a, which is easily transformed to carbamoylaminyl oxides 10a-e by further treatment with nucleophiles. The reaction of 2 and primary amines leads directly to 10f,g,the possible intermediates of type 9 not being detectable in this case.
    Notes: Sowohl im cyclischen Amidin-N-oxid 1 als auch in seinem Oxidationsprodukt, dem Radikal 2, wird die Carbonylgruppe von Nucleophilen angegriffen. Während aus 1 durch Ringöffnung die Formamidin-N2-oxide 3 entstehen, werden aus 2 verschiedene Produkte gebildet. So erhält man mit Ammoniak, sekundären Aminen oder Blausäure die Additionsprodukte 8. Mit Hydroxidionen erfolgt Ringerweiterung unter Bildung von 9a, das durch weitere Einwirkung von Nucleophilen in die Carbamoylaminyloxide 10a-e übergeht. Reaktion von 2 mit primären Aminen führt direkt zu 10f, g, ohne daß die wahrscheinlichen Zwischenstufen vom Typ 9 in diesem Falle nachgewiesen werden konnten.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197619760308
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