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  • 1
    Electronic Resource
    Electronic Resource
    Studies on canine distemper virus persistence in the central nervous system (1995)
    Springer
    Acta neuropathologica 89 (1995), S. 438-445 
    Details
    ISSN: 1432-0533
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic progressive demyelination in canine distemper virus (CDV) infection is associated with persistence of the virus in the nervous system. We studied persistence by examining expression of CDV mRNA corresponding to all genes of the virus as well as genomic CDV RNA in brain sections of dogs with acute and chronic demyelinating disease. All virus mRNAs were expressed in acute demyelinating lesions in a way similar to that seen in lymphoid tissues, the primary replication site of CDV. Their distribution corresponded very well with immunohistochemical detection of virus protein. In contrast, much more CDV mRNA than virus protein was found in gray matter areas suggesting that translation of CDV can be impaired in nervous distemper. Virus protein and RNA were cleared from chronic inflammatory demyelinating lesions. mRNA corresponding to the distal genes (F; H; L) of CDV disappeared first in inflammatory lesions for technical reasons associated with the particular mode of transcription of morbilliviruses. CDV RNA and protein persisted in chronically ill dogs in other areas of the CNS in which inflammation had not occurred. Our results suggest that persistence of CDV is favored by non-cytolytic spread of the virus and restricted infection of certain cells with reduced viral protein expression. Both tend to delay immune recognition of the virus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307649
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on canine distemper virus persistence in the central nervous system (1995)
    Springer
    Acta neuropathologica 89 (1995), S. 438-445 
    Details
    ISSN: 1432-0533
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic progressive demyelination in canine distemper virus (CDV) infection is associated with persistence of the virus in the nervous system. We studied persistence by examining expression of CDV mRNA corresponding to all genes of the virus as well as genomic CDV RNA in brain sections of dogs with acute and chronic demyelinating disease. All virus mRNAs were expressed in acute demyelinating lesions in a way similar to that seen in lymphoid tissues, the primary replication site of CDV. Their distribution corresponded very well with immunohistochemical detection of virus protein. In contrast, much more CDV mRNA than virus protein was found in gray matter areas suggesting that translation of CDV can be impaired in nervous distemper. Virus protein and RNA were cleared from chronic inflammatory demyelinating lesions. mRNA corresponding to the distal genes (F; H; L) of CDV disappeared first in inflammatory lesions for technical reasons associated with the particular mode of transcription of morbilliviruses. CDV RNA and protein persisted in chronically ill dogs in other areas of the CNS in which inflammation had not occurred. Our results suggest that persistence of CDV is favored by non-cytolytic spread of the virus and restricted infection of certain cells with reduced viral protein expression. Both tend to delay immune recognition of the virus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307649
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  • 3
    Electronic Resource
    Electronic Resource
    Cope Rearrangements versus Retro Diels-Alder ReactionsAzo Bridges from Azines, part 25; for part 24 see U. Brand, S. Hünig, K. Peters, F. Prokschy, H. G. von Schnering, Liebigs Ann. 1997, 785-789.Dedicated to Professor Dr. Dieter Seebach on the occasion of his 60th birthday (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1588-1599 
    Details
    ISSN: 0947-6539
    Keywords: azo compounds ; cycloadditions ; hydropyridazines ; pyrazolines ; rearrangements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two isomeric [4+2] cyclo-adducts from two different 1,3-dienes may result from direct cycloadditions as well as from Cope rearrangements (Scheme 1). This general question is tackled by employing two energetically different types of dienes, protonated pyrazolines (1H+, 2H+) or dihydropyridazines (3H+), prepared in situ from their trimers and alicyclic (4-6) or aliphatic (7-9) 1,3-dienes. Depending on structural features and conditions (amount of acid, reaction time), various ratios of the two isomeric [4+2] cycloadducts A and B are obtained; A and B are azo compounds 10, 14, 16, 20, 22, 24, 27, 32, 34, 36-39, 41, 42, pyrazolines endo-11, endo-13, endo-15, endo-endo-17, endo-18, endo-19, 21, 23, 25, 26, 28, and hydropyridazines 31, endo-33, endo-35, 40 and 43 (Schemes 3, 4). These results were backed by others from acid-catalyzed isomerizations, trapping experiments, and calculations of the equilibria (ΔΔH) between the isomers (by analogy with the corresponding olefins). A critical discussion reveals: a) Azo compounds 20, 22, 24, 27, 34, 38, and 42 must result from a [4++2] cycloaddition with inverse electron demand, whereas hydropyridazines endo-33, endo-35, 40, and 43 originate from a [4+2+] cycloaddition with normal electron demand. b) All isomerizations occur by a [3,3] sigmatropic rearrangement; [4+2] cycloreversion is energetically disfavored. c) A clear-cut distinction between the [4++2] or [4+2+] cycloaddition reaction routes to the energetically well-balanced systems 10→endo-11 and 12→endo-13 is not possible. d) The two cycloadditions may well favor a nonconcerted reaction through an allylic cationic intermediate which also governs the [3,3] rearrangements (Scheme 8).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970031008
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  • 4
    Electronic Resource
    Electronic Resource
    Azobrücken aus Azinen, I. Isopyrazole als elektronenarme Diene zur Synthese von 2,3-Diazabicyclo[2.2.1]heptenen (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 517-533 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azo Bridges from Azines, I. Isopyrazoles as Electron Deficient Dienes for the Synthesis of 2,3-Diazabicyclo[2.2.1]heptenesA general principle for [4⊕ + 2] cycloaddition in Diels-Alder reactions with inverse electron demand is described, where protonated azines serve as electron deficient dienes and electron rich olefins as dienophiles. This reactivity pattern is illustrated by isopyrazoles 2a and 2b. The catalytic activity of some acids is studied and the reversibility of the cycloaddition is proved. Inter alia cycloadducts (endo-14a and endo-14b) are obtained with parallel C = C/N = N bonds, which show characteristic features in their UV and NMR spectra.
    Notes: Es wird ein allgemeines Prinzip zur [4⊕ + 2]-Cycloaddition beschrieben, bei dem protonierte cyclische Azine als elektronenarme Diene in einer Diels-Alder-Reaktion mit inversem Elektronenbedarf mit elektronenreichen Olefinen reagieren. Als Beispiele dienen die Derivate 2a und 2b des Isopyrazols. Die katalytische Aktivität verschiedener Säuren wird studiert und die Reversibilität der Cycloaddition nachgewiesen. Es sind auch Cycloaddukte (endo-14a und endo-14b) mit parallelen C = C/N = N-Bindungen zugänglich, die charakteristische UV- und NMR-Spektren zeigen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170209
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  • 5
    Electronic Resource
    Electronic Resource
    7-Thiatetracyclo[4.1.0.02,4.03,5]heptan (Benzvalensulfid)  -  Synthese und Reaktionen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3213-3223 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 7-Thiatetracyclo[4.1.0.02,4.03,5]heptane (Benzvalene Sulfide)  -  Synthesis and ReactionsThe reaction of benzvalene (1) with N-(chlorothio)succinimide gives a mixture of the 1:1-adducts 5 and 6, the treatment of which with lithium aluminium hydride transforms 5 into 7-thiatetracyclo[4.1.0.02,4.03,5]heptane (4). Among the electrophiles studied only acids attack the bicyclo[1.1.0]butane portion of 4 and produce 3-thia-trans-tricyclo[4.1.0.02,4]heptanes (9) functionalized in exo-5-position. Peracids transfer an oxygen atom to the sulfur atom of 4 to give the episulfoxide 7. Bromine and chlorine transform 4, probably via the sulfenyl halide intermediates 10, into the bis(trans-3-halotricyclo[3.1.0.02,6]hex-4-yl) disulfides 11 and 12. Mixtures of the disulfides 15 and 16 and the sulfides 19 and 20 are obtained from 4 and thiophenol under the conditions of a radical reaction. Most likely the attack of a phenylthiyl radical at the sulfur atom of 4 initiates the complex reaction sequence.
    Notes: Die Umsetzung von Benzvalen (1) mit N-(Chlorthio)succinimid erbringt ein Gemisch der 1:1-Addukte 5 und 6, bei dessen Behandlung mit Lithiumaluminiumhydrid 5 in 7-Thiatetracyclo[4.1.0.02,4.03,5]heptan (4) übergeht. Als einzige der untersuchten Elektrophile greifen Säuren das Bicyclo[1.1.0]butan-System von 4 an und bringen so exo-5-funktionalisierte 3-Thia-trans-tricyclo[4.1.0.02,4]heptane (9) hervor. Persäuren übertragen auf das S-Atom von 4 ein Sauerstoff-atom unter Bildung des Episulfoxids 7. Brom und Chlor wandeln 4 wohl über die Sulfenylhalogenid-Zwischenstufen 10 in die Bis(trans-3-halogentricyclo[3.1.0.02,6]hex-4-yl)disulfide 11 und 12 um. Unter den Bedingungen einer Radikalreaktion entstehen aus 4 und Thiophenol Gemische der Disulfide 15 und 16 und der Sulfide 19 und 20. Wahrscheinlich löst die Addition eines Phenylthiylradikals an das S-Atom von 4 das komplexe Geschehen aus.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821151002
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  • 6
    Electronic Resource
    Electronic Resource
    Azo Bridges from Azines, XXIIIPart XXII. Ref.. 1,5-Laticyclic Conjugation Between Parallel Azo and o-Phenylene Bridges. Structure Dependence of [6 + 2] PhotocycloadditionsDedicated to Prof. Dr. J. Sauer on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1881-1892 
    Details
    ISSN: 0947-3440
    Keywords: Bridges, parallel o-phenylene and azo ; Dyotropic hydrogen transfer ; 1,5-Laticyclic conjugation ; [6 + 2] Photocycloaddition ; Photoelectron spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Examples were synthesized of the four systems 1, 3, 5, and 7, in which rigid parallelo o-phenylene and azo bridges are connected to five- and/or six-membered carbocyclic moities. The o-phenylene bridge was introduced by two routes: (A) starting from precursors already containing that bridge (24, 29) and assembling the azo bridge in consecutive steps (→ 3a, 3b, 5c, 5d, 5e, 5f, 5g); (B) starting from the systems with parallel C=C/N=N bridges (9a, 11a, 13a, 42) and completing the dihydro-o-phenylene ring by tetrachlorothiopene dioxide. Dyotropic hydrogen transfer of the azo bridge enhances the dehydrogenation of the intermediate dihydro-o-phenylene derivatives (22, 3cH2, 25). This mechanism was proved by the domino hydrogen transfer 44 → 45 → 5h. Via route B, systems 1a, 1b, 3c, 3d, 5a, 5b, 5h, and 43 were obtained. In sharp contrast to the smooth [2 + 2] photocycloaddition of systems 9, 11, 13, and 15 (C=C/N=N bridges), [6 + 2] photocycloaddition occurs only with systems 1 and (5C/5N) and 3 (6C/5N) but not with systems 5 (5C/6N) and 7 (6C/6N). These differences are not caused by slightly varying distances of the two bridges (X-ray data) but by the higher n_ ionization energy of the azo group incorporated into a 2,3-diazabicyclo[2.2.1]hept-2-ene (DBH) instead of a 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) moiety, the hypsochromicity of the corresponding DBH n-π* state and the higher ground-state energy of DBH compared to DBO.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961125
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  • 7
    Electronic Resource
    Electronic Resource
    Photoelectron and UV spectroscopic investigations of homoconjugative interactions between parallel C=C and N=N bonds (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 543-553 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelektronen- und UV-spektroskopische Untersuchungen zur Homokonjugation zwischen parallelen C=C- und N=N-BindungenDie Photoelektronen- und UV-Spektren von Diazaisodrinen 4 und 5 wurden gemessen und analysiert. Die beträchtliche Homokonjugation zwischen C=C- und N=N-Bindungen spiegelt sich in einem deutlich destabilisierten π-Orbital vom Norbornentyp wider. Die UV-Spektren wurden mit Hilfe der CNDO-CI-Methode interpretiert, und es ergab sich eine ausgezeichnete Übereinstimmung zwischen beobachteten und berechneten Werten. Der transanulare π- →+*-Übergang, der im Stammkohlenwasserstoff nicht erkennbar ist, läßt sich im Diazaderivat leicht identifizieren. Röntgenstrukturanalysen von 4a und 5a bestätigen im wesentlichen die durch semiempirische Methoden erhaltenen Strukturvorschläge.
    Notes: The photoelectron and UV spectra of diazaisodrin systems 4 and 5 have been measured and analyzed. The strong homoconjugative interaction between the C=C and N=N bond is reflected in a particular destabilized position of the norbornene type π orbital. The UV spectra have been assigned using a CNDO-CI treatment and excellent agreement between observed and calculated values has been achieved. The transanular π- →+* transition which is not discernible in the parent hydrocarbon can easily be identified in the diaza derivative. X-ray structure determination of 4a and 5a confirms the conclusions arrived at by semiempirical calculations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190218
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  • 8
    Electronic Resource
    Electronic Resource
    Photoelektronenspektroskopische Untersuchungen an Hexahydro-1,3,5-triazinen (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 554-562 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectroscopic Investigation of Hexahydro-1,3,5-triazinesThe PE spectra of the 1,3,5-trialkylhexahydro-1,3,5-triazines 1 - 4, of tri-1-pyrroline (5), α-tripiperideine (6), hexamethyltriisopyrazole (7) and of tri-4,5-dihydropyridazine (8) or those of their decomposition products have been obtained and interpreted with respect to the electronic structure and the conformation of the compounds. The spectra of 1 - 6 are consistent with a diequatorial-monoaxial arrangement of the nitrogen substituents in the hexahydro-1,3,5-triazine ring. 7 probably has a monoequatorial-diaxial conformation. The spectrum obtained from 8 is not in accord with the presence of the trimeric form in the gas phase.
    Notes: Die PE-Spektren der 1,3,5-Trialkylhexahydro-1,3,5-triazine 1 - 4, des Tri-1-pyrrolins (5), des α-Tripiperideins (6), des Hexamethyltriisopyrazols (7) und des Tri-4,5-dihydropyridazins (8) sowie diejenigen einiger Zerfallsprodukte wurden aufgenommen und hinsichtlich der elektronischen Struktur und der Konformation der Verbindungen ausgewertet. Die PE-Spektren von 1 - 6 stehen mit einer diäquatorial-monoaxialen, dasjenige von 7 mit einer monoäquatorial-diaxialen Stellung der Stickstoffsubstituenten am Hexahydro-1,3,5-triazin-Ring im Einklang. Das von 8 erhaltene Spektrum spricht gegen das Vorliegen dieser Verbindung in trimerer Form in der Gasphase.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190219
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  • 9
    Electronic Resource
    Electronic Resource
    Azobrücken aus Azinen, VI Substituierte Isopyrazole als elektronenarme Diene zur Synthese von 2,3-Diazabicyclo[2.2.1]heptenen und deren Photoreaktionen (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 477-483 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The [4+ + 2] cycloaddition of isopyrazoles (4H-pyrazoles) 3c-e and cyclopentadiene, norbornene, and norbornadiene leads to the azo-bridged products 5, 8, 11 and 12c-e. Irradiation of 5e, 8e and 11e expectedly produces the tricycles 13, 15 and 17 by loss of nitrogen. In contrast, as a result of the parallel arrangement of the C=C/N=N bonds, the isomers 12c-e are transformed nearly quantitatively into diazetidines 14, 16 and 18; despite the pronounced photolability of the diazabicycloheptene moiety in 12, [2 + 2] cycloaddition is preferred over nitrogen elimination.
    Notes: Aus Isopyrazolen (4H-Pyrazolen) 3c-e und Cyclopentadien, Norbornen und Norbornadien entstehen unter [4+ + 2]-Cycloaddition 5, 8, 11 und 12c-e. Bestrahlung von 5e, 8e und 11e führt erwartungsgemäß unter N2-Verlust zu den Tricyclen 13, 15 und 17, während aus den Isomeren 12c-e mit parallelen C=C/N=N-Bindungen unter [2 + 2]-Cycloaddition fast quantitativ die Diazetidine 14, 16 und 18 entstehen, trotz der großen Photolabilität des in 12 vorhandenen Diazabicycloheptengerüstes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200406
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  • 10
    Electronic Resource
    Electronic Resource
    Azobrücken aus Azinen, VII1) Diels-Alder-Reaktionen mit inversem Elektronenbedarf zwischen Isopyrazolen und Cycloalkenen sowie Cycloalkadienen. - Ein Vergleich von Säure-Katalyse und Beschleunigung durch Druck (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 2041-2051 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azo Bridges from Azines, VII1). - Diels-Alder Reactions with Inverse Electron Demand between Isopyrazoles add Cycloalkenes or Cycloalkadienes. - A Comparison of Acid Catalysis and Acceleration by PressureThe acid-catalysed reaction of the isopyrazoles 1 and 2 with the cycloalkenes 3-8, norbornene (9), 1,4-cyclohexadiene (18), 1,5-cyclooctadiene (19), norbornadiene (20), and benzonorbornadiene (21) yields the expected azo-bridged cycloadducts 10-17 and 22-27. From 19 are also obtained the bisadducts 24a and 24b. At higher pressure (7 kbar) the non-acid-catalysed reaction of 2 and the previously mentioned olefines produces the respective cycloadducts usually in higher yields. In the case of 20 the additional bisadducts exo,exo-26b and endo,exo-26b are formed. Reaction rates for the (pressure-controlled) cycloadditions correlate with the reaction enthalpies of the cycloaddition between cycloalkenes and 1,3-cyclopentadiene. The exo/endo ratio of cycloadducts 25b, formed from 2 and 20 proves to be independent of temperature and pressure.
    Notes: Die Isopyrazole 1 und 2 liefern unter Säurekatalyse mit den C3—C8-Cycloalkenen (3-8) sowie mit Norbornen (9), 1,4-Cyclohexadien (18), 1,5-Cyclooctadien (19), Norbornadien (20) und Benzonorbornadien (21) die erwarteten Cycloaddukte 10-17 und 22-27 mit Azobrücke. Mit 19 entstehen dabei auch die Bisaddukte 24a und 24b. Ohne Säurekatalyse bilden sich aus 2 und den Olefinen die entsprechenden Cycloaddukte unter 7 kbar Druck meist in höherer Ausbeute, mit 20 zusätzlich die Bisaddukte exo,exo-26b und endo,exo-26b. Die unterschiedlichen Reaktionsgeschwindigkeiten der Cycloalkene bei Reaktionen unter Druck korrelieren mit den Reaktionsenthalpien für die Addition von 1,3-Cyclopentadien. Das exo/endo-Verhältnis der Cyclo-addukte 25b aus 2b + 20 erweist sich druck- und temperatur-unabhängig.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871201216
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