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  • 1
    Electronic Resource
    Electronic Resource
    Cycloadditionen von 6H-1,3,4-Oxadiazin-6-onen (4,5-Diaza-α-Pyronen). 14. Nicht katalysierte und durch Trifluoressigsäure katalysierte Reaktionen von 6H-1,3,4-Oxadiazin-6-onen mit NorbornenHerrn Prof. Dr. Rolf Huisgen zum 75. Geburtstag gewidmet (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 659-674 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones). 14. Reactions of 6H-1,3,4-Oxadiazin-6-ones with Norbornene: Non-catalysed and Catalysed by Trifluoroacetic AcidIn 11 out of 13 non-catalysed reactions of oxadiazinones 1 with norbornene, γ-oxoketenes 4 were observed and could be isolated in three cases (4b,d,m). Except for 4m, all γ-oxoketenes isomerised to enollactones of type 5 on thermolysis. However, 4b furnished the cyclobutene derivative 10 as the major product. No γ-oxoketenes were detected in the reactions of 1k and 1l, which gave rise to the formation of 5k and the enollactone 19, respectively. The latter was converted into 5l on treatment with trifluoroacetic acid (TFA). Four oxadiazinones 1 were allowed to react with norbornene in the presence of TFA. Three of them (1a,b,l) afforded mixtures of enollactones of type 5 and their diastereomers 12. Heating of 4 in the presence of norbornene led to the formation of the symmetrical δ-lactones 6. This process was observed to be efficient only where the conversion 4 → 5 is slow (4b) or inoperative (4m). In five cases, the treatment of the components with boron trifluoride etherate proved to be a useful preparative alternative (6a,d,g,h,m). On treatment of 4a with methanol, the pseudoester 7a was formed, whereas 4b gave mixtures of 7b and the esters 8b and 15. Hydrogen chloride converted 4b into the pseudochloride 14, which furnished pseudoester 7b on methanolysis. Reaction of 4b,m with formic acid gave rise to pseudoanhydrides of type 13. From 4b and TFA a mixture of the enollactones 5b and 12b was obtained. Boron trifluoride etherate transformed 4i to enollactone 12i; analogously, 12m resulted on treatment of 4m with trifluoromethanesulfonic acid.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.199533701140
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  • 2
    Electronic Resource
    Electronic Resource
    Cycloadditionen von 6H-1,3,4-Oxadiazin-6-onen (4,5-Diaza-α-pyronen), 13[1]. Diels-Alder-Reaktionen mit 6H-1,3,4-Oxadiazin-6-onen als Dienophil (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1743-1748 
    Details
    ISSN: 0009-2940
    Keywords: 6H-1,3,4-Oxadiazin-6-ones ; 1,2-Bismethylenecyclohexane ; Diels-Alder reactions ; [1,3,4]Oxadiazino[4,5-b]isoquinolin-1-one derivatives ; Bicyclo[2.1.1]hexan-5-one, highly substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones), 13[1].-Diels-Alder Reactions with 6H-1,3,4-Oxadiazin-6-ones as Dienophile2,5-Diphenyl-1,3,4-oxadiazin-6-one (1b) reacted as dienophile with 2,3-dimethyl-1,3-butadiene to afford the pyridooxadiazinone 5. Analogously, the oxadiazinoisoquinolines 7c- e were formed on treatment of 2-(4-nitrophenyl)- (1c), 2-(4-tolyl)- (1d), and 2-(4-bromophenyl)-5-phenyloxadiazinone (1e) with 1,2-bis(methylene)cyclohexane (6). In contrast, the methyl oxophenyloxadiazinecarboxylate 1a gave a low yield of the cyclopentenone derivative 8 and 7a in the ratio 2.3:1.0. A third type of product, i.e. the cyclobutanone derivative 9, resulted on exposure of the anisyl(isopropyl)oxadiazinone 1f to 6. The oxadiazinones 1d, e, f have been prepared for the first time. X-ray structure analyses established the identity of the compounds 7d and 9.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260734
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  • 3
    Electronic Resource
    Electronic Resource
    Benzofuran dioxetanes, a new class of mutagenic agents: Synthesis by photooxygenation of benzofuran derivatives (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 33-40 
    Details
    ISSN: 0170-2041
    Keywords: Benzofurans ; Singlet oxygen ; Photooxygenation ; Dioxetanes ; Mutagenicity ; Ames test ; Salmonella typhimurium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetraphenylporphine-sensitized photooxygenation of benzofuran derivatives 1 afforded the corresponding benzofuran dioxetanes 2 in good yields. Allylic hydroperoxides 3 were formed regioselectively from 2,3-dimethyl-substituted benzofurans as minor products, except in the case of the benzofuran 1d, which gave predominantly the hydroperoxide 3d. The relative reactivities of the benzofurans toward singlet oxygen depended on the nature of substituents at the C-2 and C-3 positions of the furan rings. The benzofuran dioxetanes 2 were strongly mutagenic in the Salmonella typhimurium strain TA 100, their mutagenicity depending on the type of substituents of the dioxetane and of the benzo rings.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199119910106
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