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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 350-354 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free Radical Reactions of N-Heterocyclic Compounds. XIII. Oxidation of Cyclic Hydrazo Compounds with 2,4,6-Tri-tert-butyl-phenoxy Radical and Reactions of Radical Combination ProductsN-Heterocyclic compounds 1a, b containing the hydrazo structure were oxidized with 2,4,6-tri-tert-butyl-phenoxy radical (2). It was shown that the oxidation did not lead to the azo compounds 5a, b, but rather to radical combination products 6a, b of 2 via the intermediate hydrazyls 4a, b. The decomposition of adducts 6a, b was found to be similar to the reaction of radical combination products of aryl hydrazyls and CH-acidic compounds. The main reactions consisted of cleavage to starting radicals or elimination of isobutene forming the respective phenolic compounds 13a-c.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 287-289 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0947-6539
    Keywords: dioxiranes ; epoxidations ; insertions ; oxenoids ; radicals ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimethyldioxirane oxidation of α-methylstyrene, trans-cyclo-octene, and 1-vinyl-2,2-diphenylcyclopropane gave, under all reaction conditions employed, the corresponding epoxides in high yields. No radical products from allylic oxidation, from trans/cis isomerization, or from cyclopropylcarbinyl rearrangement (radical clock) were observed. Even for these alkenes, which are prone to radical reactions, the previously established electrophilic concerted mechanism applies, rather than the recently proposed radical mechanism. The selective hydroxylation of (-)-2-phenylbutane by dimethyldioxirane gave only (- )-2-phenylbutan-2-ol with complete retention of configuration and no loss of optical purity. Thus, a radical-chain oxidation is also discounted in the oxygen insertion into hydrocarbon C-H bonds for dioxiranes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 671-678 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Free Radical Reactions of N-Heterocyclic Compounds, VI. - Radical Reactions of Cyclic 2,2-Diacyl-1-arylhydrazyls. - A New N—N Bond Cleavage ReactionDiacylhydrazyl radicals 5 are generated from N-(phenylamino)-dicarboximides 1, 2a, b, 3a-f, and 4 by oxidation with different oxidants. The intermediates 5 react in two ways depending on the substituents in the anilino group. Dimerization of the hydrazyl radicals 5 to stable tetrazanes 8 is favoured by acceptor substituents in the Ar group. N—N bond dissoziation (α-decomposition) of the hydrazyl radicals 5 is favoured by donor substituents in the phenyl ring of the anilino group. The fragments of such reactions are imide radicals 22 and phenylnitrenes 23. The formation of these fragmentation products is proven by analysis of the reaction products. The formation of benzoxazole (25) (15% yield) is an evidence for an intramolecular insertion reaction of the o-methoxyphenylnitrene, generated by oxidation of 3e. The hydrazyl radicals 5 are also trapped by the stable free radical 2,4,6-tri-tert-butylphenoxyl (9). The thermal decomposition of the isolated radical adducts was studied.
    Notes: Die Diacylhydrazyl-Radikale 5 werden aus den N-(Phenylamino)dicarbonsäureimiden 1, 2a, b, 3a-f und 4 durch Oxidation mit verschiedenen Oxidantien erzeugt. Die Radikale 5 reagieren auf zwei Wegen: a) Dimerisation zu Tetrazanen 8, die durch Akzeptorsubstituenten im Anilinorest begünstigt wird; b) durch N—N-Bindungsspaltung, wobei Imid-Radikale 22 und Phenylnitrene 23 entstehen, bei donatorsubstituierten Anilinogruppen. Die Spaltprodukte werden als Folgeprodukte nachgewiesen, so Benzoxazol (25) (15%), das durch Oxidation von 3e über das intermediäre o-Methoxyphenylnitren gebildet wird. Die Hydrazyl-Radikale 5 konnten durch 2,4,6-Tri-tert-butylphenoxyl (9) abgefangen werden. Die Zersetzung der isolierten Abfangprodukte wurde untersucht.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1729-1733 
    ISSN: 0009-2940
    Keywords: Pyrazoles ; Aminyls, heterocyclic ; Pyrazolo[1,5-a]benzimidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free Radical Reactions of N-Heterocyclic Compounds, XIV[1]. - Oxidative Cyclization of Anilinopyrazoles to Pyrazolo[1,5-a]benzimidazolesHerrn Professor Christoph Rüchardt zum 65. Geburtstag gewidmet.Substituted Anilinopyrazoles 1 were oxidized by dibenzoyl peroxide or lead(IV) oxide. Different oxidation products were isolated depending on the substituents in the anilino group of anilinopyrazoles 1. Intermediate pyrazolyl radicals 5, which could be trapped by triphenylmethyl or phenoxyl radicals, undergo cyclization reaction with formation of pyrazolo[1,5-a]benzimidazoles 4. The structures of compounds 4 were proven by 1H- and 13C-NMR spectroscopy, 15N labeling and transformation of 4e to the betain 7e.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1983-1987 
    ISSN: 0009-2940
    Keywords: Amidrazones ; 1,2,4-Triazinones ; Oxidation ; Azo compounds, new type of ; Hydroperoxides, new type of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radical Reactions on N-heterocyclic Compounds, IX.  -  Oxidation reactions of Cyclic AmidrazonesThe cyclic amidrazone derivatives 1 and 2 were oxidized with dibenzoyl peroxide or bromine to give the dehydro derivatives 5 and 6, respectively. Oxidation of 2 or 6 by Fremys salt yields the quinone imine 7. Treatment of the cyclic amidrazone 3 with Ag2O afforded, via an isolable silver complex, which was decomposed by nitric acid, the 1,2-dihydro-1,2,4-triazine-5,6-dione 9 and the 1,6-dihydro-1,2,4-triazin-5(2H)-one 10. From 3 the dimer bis(1,4,5,6-tetrahydro-4-nitroso-1,2,4-triazine) 11 is formed in the usual manner. On irradiation or thermal treatment 11 yields the 1-(p-nitrophenyl) derivative 12 of 3. Photolysis of 11 in the presence of O2 leads to the hydroperoxides 13 and 14, compounds of a new peroxide type. Degradation of 13 with mineral acid leads to the unusual imido azo compound 17, reaction of 13 and 14 with bases affords the corresponding keto compounds 15 and 16. 2,5-Dihydro-1,3-diphenyl-1,2,4-triazin-6(1H)-one (4) reacts with three equivalents of the stable 2,4,6-tris-tert-butylphenoxyl radical (18) to form hippuric acid (19) and phenyldiimide (21).
    Notes: Die cyclischen Amidrazon-Derivate 1 und 2 werden mittels Dibenzoylperoxid oder Brom zu den entsprechenden Dehydroverbindungen 5 bzw. 6 oxidiert. Aus 2 und auch aus 6 entsteht durch Oxidation mit Fremys Salz das Chinonimin 7. Das cyclische Amidrazon 3 liefert mit Ag2O einen isolierbaren Silberkomplex, nach dessen Zersetzung mit Salpetersäure das 5,6-Diketo-Derivat 9 und das 5-Keto-Derivat 10 isoliert werden. Das durch Nitrosierung aus 3 dargestellte Dimer Bis(1,4,5,6-tetrahydro-4-nitroso-1,3-diphenyl-1,2,4-triazin) 11 reagiert bei UV-Belichtung oder thermisch zum 1-(p-Nitrophenyl)-Produkt 12 von 3. In Gegenwart von O2 führt die Photolyse von 11 zu den Hydroperoxiden 13 und 14, Verbindungen eines neuartigen Peroxid-Typs. Mit Mineralsäure wird aus 13 die Imido-azo-Verbindung 17 gebildet. Durch Basenzersetzung der Hydroperoxide 13 und 14 entstehen die entsprechenden cyclischen Diketoverbindungen 15 und 16. 2,5-Dihydro-1,3-diphenyl-1,2,4-triazin-6(1H)-on (4) reagiert quantitativ mit drei Äquivalenten des stabilen 2,4,6-Tri-tert-butylphenoxyls (18) zu Hippursäure und Phenyldiimid (20).
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free Radical Reactions of N-Heterocyclic Compounds. VIII. ESR-Investigations on the N,N-Bond Cleavage Reaction of Cylic 2,2-Diacyclhydrazinoxyls2,2-Diacylhydrazinoxyls (2) undergo decomposisition to new nitroxides 3 in the presence of bis (acetylacetonato) cobalt (II), tert.-butyl hydroperoxide and an alcohol (i.e. methanol, ethanol, i.-propanol). These new radials 3 are spin trap products of nitrosoarenes, formed by a fragmentation process of 2 and of ligand radicals, generated from bis (acetylacetonato) cobalt (II) by oxidation with tert.-butyl hydroperoxide. The e. s. r. data of the radicals 2, 3 and of the 3-isomeric radicals 5 and 6 are compared.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2075-2079 
    ISSN: 0009-2940
    Keywords: Hydrazines ; cyclic ; 1,2-diacyl- ; Oxidation ; Hydrazyls ; Hydrazine oxyls ; ESR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free Radical Reactions of N-Heterocyclic Compounds, X[1]. - Radical Reactions of Cyclic 1,2-DiacylhydrazinesCyclic 1,2-diacylhydrazyls 3 have been detected by ESR spectroscopy during oxidation of the corresponding NH compounds 2. The N coupling constants are determined and confirmed by simulation and by 15N labeling. The hydrazyls 3 react by dimerization to the corresponding tetrazanes of type 5 or by β scission to the diacyl azo compounds 4 and C radicals. The β scission of the radicals 3 is elucidated by UV/Vis detection of the azo compound 4b and reaction of 4b to Diels-Alder adducts. The alkyl radicals are trapped by nitrosobenzene (8) (ESR).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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