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  • 1
    Electronic Resource
    Electronic Resource
    Vagus nerve stimulation attenuates the systemic inflammatory response to endotoxin (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 405 (2000), S. 458-462 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Vertebrates achieve internal homeostasis during infection or injury by balancing the activities of proinflammatory and anti-inflammatory pathways. Endotoxin (lipopolysaccharide), produced by all gram-negative bacteria, activates macrophages to release cytokines that are potentially ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35013070
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  • 2
    Electronic Resource
    Electronic Resource
    Newly expressed SUR1-regulated NC Ca-ATP channel mediates cerebral edema after ischemic stroke (2006)
    [s.l.] : Nature Publishing Group
    Nature medicine 12 (2006), S. 433-440 
    Details
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Pathological conditions in the central nervous system, including stroke and trauma, are often exacerbated by cerebral edema. We recently identified a nonselective cation channel, the NCCa-ATP channel, in ischemic astrocytes that is regulated by sulfonylurea receptor 1 (SUR1), is opened by depletion ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nm1390
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  • 3
    Electronic Resource
    Electronic Resource
    Ring Expansion of 2-Alkylidenedihydroquinazolines to Iminodihydro-1,4-benzodiazepines by Methanesulfonyl and Trifluoromethanesulfonyl Azide (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1577-1587 
    Details
    ISSN: 1434-193X
    Keywords: Azides ; Cleavage reactions ; Cycloadditions ; Nitrogen heterocycles ; Polycycles ; Ring expansion ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---2-Alkyl-1-methylquinazolinium hexafluorophosphates 9 are deprotonated by sodium or potassium hydride to afford solutions of 2-alkylidenedihydroquinazolines 10, which were investigated by NMR spectroscopy. Trapping with methanesulfonyl azide (5a) of 10 in situ or subsequent treatment with trifluoromethanesulfonyl azide (5b) gives mixtures of colourless (15) and intensely yellow N-sulfonylimino-1,4-benzodiazepines 16 along with products due to cleavage of the exocyclic double bond of 10, viz. 11 and 13. The ethylidene compound 10b yields the bicyclic products 18 and 19, apparently by complex sequences of reactions that are triggered by removal of the acidic proton at C-2 of 16b and 16f. The structures of the products are based on spectroscopic evidence and X-ray diffraction analyses performed on 15b, 16d, 16e, and 19.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Ring Expansion of 2-Alkylidenedihydroquinolines to 2-Iminodihydro-1-benzazepines by Phenyl, Methanesulphonyl, and Trifluoromethanesulphonyl Azide[1] (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 507-520 
    Details
    ISSN: 1434-193X
    Keywords: Azides ; Cleavage reactions ; Cycloadditions ; Nitrogen heterocycles ; Photolysis ; Ring expansion ; Spiro compounds ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---2-Alkyl-1-methylquinolinium hexafluorophosphates 1 are deprotonated by sodium or potassium hydride to afford solutions of 2-alkylidenedihydroquinolines 2, which are investigated by NMR spectroscopy. 1,3-Dipolar cycloaddition of phenyl azide to 2 yields the spirocyclic products 10. While, at 80-110 °C, the [3 + 2] cycloaddition that afforded (u)-10f is reversible and accompanied by epimerisation to give (l)-10f, thermolysis of the dimethyl compounds 10b and d affords the ring-expanded products 14b and d, respectively, in good yields along with molecular nitrogen. Irradiation of 10d with light of λ 〉 320 nm results in the formation of similar amounts of 14d and [3 + 2] cycloreversion products, viz. 2-diazopropane (5b) and the N-phenylimine 15d. - Trapping of 2 by methanesulphonyl azide (18a) gives mixtures of the products of ring expansion (21b, d-f, 10-50 %) and [3 + 2] cycloreversion (22a, d, 10-80 %) of the apparently very labile intermediate spirocyclic cycloadducts 19. The ratio of 21 vs. 22 is significantly improved when 18a is replaced by trifluoromethanesulphonyl azide (18b), which affords the iminodihydrobenzazepines 21i-k in 50-75 % yield. The structures of the products are based on NMR evidence and X-ray diffraction analyses performed with 21b, d, and (ax,E)-21e.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Ring Expansion vs. Cleavage of the Exocyclic Double Bond of 2-Cycloalkylidenedihydrobenzothiazoles and -benzimidazoles by Methanesulfonyl Azide (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1229-1233 
    Details
    ISSN: 1434-193X
    Keywords: Azides ; Cleavage reactions ; Cycloadditions ; Nitrogen heterocycles ; Ring expansion ; Sulfur heterocycles ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Deprotonation of the 2-cycloalkylbenzothiazolium perchlorates 1f-h with sodium hydride in the presence of methanesulfonyl azide (3) affords the spirocyclic dihydro-1,4-benzothiazines 9f-h together with small amounts of the 2-iminobenzothiazole 5. The 2-cycloalkylidenedihydrobenzimidazoles 11e-h are generated by deprotonation with potassium hydride from the corresponding 2-cycloalkylbenzimidazolium salts 10e-h, and trapped with 3 to yield the zwitterions 12e-h. Whereas 12h is thermally unstable, 12e-g are isolated and thermolysed at 20-80 °C. The cyclopropyl zwitterion 12e decomposes in an ill-defined way, only at temperatures above 80 °C. In contrast, 12f,g, and, in particular, 12h, decompose more readily to furnish the products of ring expansion (13f-h) and those of a [3 + 2] cycloreversion (6 and 14) of intermediate spirocyclic triazolines. Products that might be indicative of the intervention of hypothetical zwitterions of type 8 cannot be detected.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Tetraacylethenes as Dienophiles and Hetero Dienes in Two-Step Diels-Alder Reactions (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3343-3351 
    Details
    ISSN: 1434-193X
    Keywords: C-C coupling ; Cycloadditions ; Dehydrogenations ; Electron deficiency ; Isomerisations ; Oxidations ; Zwitterionic intermediates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation with barium manganate of the enol of tetraacetylethane (10) affords tetraacetylethylene (7a) in good yield. Treatment of the 1,3-diketones 15a and b with iodosobenzene in the presence of boron trifluoride does not result in oxidative coupling yielding 10 and diacetyldibenzoylethane 17, respectively, as has been reported by Moriarty et al. Instead the known difluoroborylenolates 16 are formed. Oxidative coupling of the sodium enolate of 15b with iodine affords the meso-tetraketone meso-17 and diacetyldibenzoylethylene (E)-7b besides small amounts of rac-17 and the bisenol 19. In the presence of 1,4-diazabicyclo[2.2.2]octane, meso-17 and 19 tautomerise yielding identical equilibrium mixtures of meso-17, rac-17, and 19 (26:29:45). Dehydrogenation with 5,6-dichloro-2,3-dicyanobenzoquinone of meso-17 yields (E)-7b and an isomer (77:23) which was assigned structure (Z)-7b on the basis of spectroscopic evidence. - Tetraacetylethylene (7a) reacts with 1,2-dimethylenecyclohexane to afford two different [4+2]cycloadducts, viz. the spirocyclic dihydropyran 25 (30 %) and the tetraacetyloctalin 27. Whereas the latter is stable, the former isomerises to the latter on heating. Formation of both [4+2]cycloadducts and the isomerisation 25 → 27 are interpreted by invoking the zwitterion 26 as common intermediate. Monoolefines that cannot generate stable carbenium ions don't give [4+2]cycloadducts with 7a. In contrast, α-methylstyrene yields the oxa Diels-Alder product 30. The structures of (E)-7b, 19, 25, and 27 are established by X-ray diffraction analyses.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Ring Expansion of Heterocyclic Ketene N,X-Acetals and 2-Alkylidenedihydroindoles with Methanesulphonyl Azide by [3 + 2] Cycloaddition and Subsequent Extrusion of Molecular Nitrogen (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1541-1549 
    Details
    ISSN: 0947-3440
    Keywords: [3 + 2] Cycloaddition ; Ketene N,X-acetals, cyclic ; Azides, electrophilic ; Amidines, cyclic N-sulphonyl- ; Ring expansion of heterocycles ; 1,2-Shift of carbon, nitrogen, sulphur, or selenium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methanesulphonyl azide (2) reacts readily with isolated cyclic ketene N,X-acetals of type 1, viz. 10a, d, 15b, d, and 22a-c, or those that are generated in situ by deprotonation of the corresponding 2-alkylbenzazolium tetrafluoroborates, i.e. 14a → 15a, 14b → 15b, and 18 → 19. Ring-expanded products are formed by extrusion of molecular nitrogen from intermediate labile [3 + 2] cycloadducts 3 with concomitant 1,2-shift of N (route A1 → 12, 24) or X (route A2 → 16, 20, 21). In addition, 3 may undergo [3 + 2] cycloreversion into N-sulphonylimine 5 and diazoalkane 6 (route B → 13, 17, 25). The configurations of the cyclic N-sulphonylamidines 16b and 21b, the N-sulphonylimine 24 and the N-sulphonylamine 27 are elucidated by means of X-ray diffraction analyses. The ratio of the (useful) ring-expansion reactions vs. the unwanted formation of 5 + 6 is hardly influenced by the solvent employed and temperature of the experiment but strongly by the nature of the potential migrating atom and the substituents at the α-carbon atom.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961008
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  • 8
    Electronic Resource
    Electronic Resource
    Zwitterions as Intermediates in 1,3-Dipolar Cycloadditions of Electrophilic Azides to 2-Alkylidenetetrahydroimidazoles and 2-AlkylidenedihydrobenzimidazolesDedicated to Professor Günter Szeimies on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1551-1558 
    Details
    ISSN: 0947-3440
    Keywords: Ketene N,N-acetals, cyclic ; Imidazole, derivatives of ; Benzimidazole, derivatives of ; Azides, electrophilic ; Cycloaddition, 1,3-dipolar, nonconcerted ; Zwitterions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic ketene N,N-acetals derived from imidazolidine (4a, c) and 2,3-dihydrobenzimidazole (6a-c) add methanesulphonyl azide (2a) or picryl azide (2f) to afford the zwitterions 5 and 7, respectively. The structure of 7d is elucidated by X-ray crystallography. Reversibility of formation and thermal stability of the N-sulphonyl zwitterions depend on the substitution pattern at the carbon atom to which the triazenide moiety is attached: In the case of a pair of geminal methyl groups (5a, 7a) formation is irreversible and decomposition by cyclisation and subsequent reactions occurs above -20°C, while in presence of a single alkyl group (7c, d) these processes require heating to 80°C and are accompanied by partial reversion to 2a and ketene N,N-acetals (6b, c). Cyclisation of the zwitterions yields intermediate spirocyclic [3 + 2] cycloadducts, which may undergo [3 + 2] cycloreversion into N-sulphonylimine 13 and diazo compound 14 or extrude molecular nitrogen to furnish ring-expanded 2-(sulphonylimino)piperazine derivatives (9, 11).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961009
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