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  • 1
    Electronic Resource
    Electronic Resource
    Synthese neuartig substituierter Pyridazin-6(1H)-one (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 341-347 
    Details
    ISSN: 1434-4475
    Keywords: Chloroacetic acid chloride ; Phenylhydrazono acetamides ; Pyridines ; Pyridazin-5-ylpyridinium chlorides ; 4,5-Diamino-pyridazin-6(1H)-ones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Arylhydrazono acetamides1 react with chloroacetic acid chloride to give N-chloroacetyl derivatives2. Subsequent reaction with pyridines followed by ring closure yield 1-(4-amino-6-oxo-pyridazin-5-yl)-pyridinium chlorides3. Analogously, 1-(6-oxo-pyridazin-5-yl)-pyridinium chloride (5) and 6-oxo-5-pyridinio-pyridazin-4-olate (4) are formed from phenylhydrazono derivatives and pyridine. Treatment of3 and4 with hydrazinium hydrate gives 4,5-diamino-6-oxo-pyridazin-3-carbohydrazides6 and 5-amino-4-hydroxy-pyridazin-6(1H)-one (8). An analogous ring cleavage of3e and5 gives rise to 4,5-diamino- and 5-amino-pyridazin-6(1H)-ones7. On treatment of the pyridinium salts3 with caustic soda in water, nucleophilic addition of the amino group to the pyridinium ring takes place and stable dehydrated products9 are isolated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00816103
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  • 2
    Electronic Resource
    Electronic Resource
    Syntheses with pyridinium and sulfonium salts of acylated β-enaminonitriles (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 711-723 
    Details
    ISSN: 1434-4475
    Keywords: Malononitrile ; Benzoles ; Pyridines ; Thiophenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Pyridinium- und Sulfoniumsalze2a–e, die aus 3-Amino-2-(α-halo-acetyl)-crotonsäurenitril und 3-Amino-2-(α-halo-acetyl)-zimtsäurenitril hergestellt werden können, reagieren mit Malonsäuredinitril in Gegenwart einer Base zu 3-Amino-2-pyridinio-phenolaten3a,b und 3-Amino-2-sulfonio-phenolaten3c–e. In Analogie wurden 3-Amino-2-(diethyloxyphosphoryl)-phenol5a und 3-Amino-2-(p-tolyl-sulfonyl)-phenol5b erhalten. 2,3-Diamino-phenole6a,b werden aus den Pyridiniumsalzen3a,b gebildet. Das Verhalten der Pyridiniumsalze2a,b gegenüber Heterokumulenen ist untersucht worden. Cyanamid führt zum (2-Amino-4-hydroxy-pyrid-3-yl)-pyridiniumsalz8c. Phenylisothiocyanat liefert die 3-Pyridinio-2-thioxo-pyridin-4-olate9a,b. In Abhängigkeit vom Substituenten in der Position 6 entsteht bei der Reaktion mit Schwefelkohlenstoff ein 3-Pyridinio-2-thioxo-pyridin-4-olat10 oder ein 3-Pyridinio-2-thioxo-thiopyran-4-olat11. Phenylisocyanat reagiert zum Pyrimidin-2,4-dion12 unter Verlust von N-Methyl-pyridiniumchlorid. S-Methylierung von9a und Spaltung des Pyridiniumringes ergibt das 3-Amino-2-methylthio-pyrid-4-on14. Die Verbindungen wurden1H- und13C-NMR-spektroskopisch untersucht.
    Notes: Summary Pyridinium and sulfonium salts2a–e which can be prepared from 3-amino-2-(α-haloacetyl)-crotonitriles and 3-amino-2-(α-halo-acetyl)-3-phenyl-acrylonitriles react with malononitrile in the presence of a base to 3-amino-2-pyridinio-phenolates3a,b and 3-amino-2-sulfonio-phenolates3c–e. In an analogous way, 3-amino-2-(diethyloxyphosphoryl)-phenol5a and 3-amino-2-(p-tolyl-sulfonyl)-phenol5b have been prepared. 2,3-Diamino-phenoles6a,b are formed from the pyridinium salts3a,b. The behaviour of the pyridinium salts2a,b towards heterocumulenes has been investigated. Cyanamide leads to the (2-amino-4-hydroxy-pyrid-3-yl)-pyridinium salt8c. Phenylisothiocyanate gives the 3-pyridinio-2-thioxo-pyridin-4-olates9a,b. Carbon disulfide gives rise to 3-pyridinio-2-thioxo-pyridin-4-olate10 or 3-pyridinio-2-thioxo-thiopyran-4-olate11, depending on the substituent at the 6-position. Phenylisocyanate reacts to the pyrimidin-2,4-dione12 with loss of N-methyl-pyridinium chloride. S-methylation of9a and cleavage of the pyridine moiety yields the 3-amino-2-methylthio-pyrid-4-one14. The structures were investigated by1H and13C NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807162
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  • 3
    Electronic Resource
    Electronic Resource
    On the Stability of the O(N)-Invariant and the Cubic-Invariant Three-Dimensional N-Component Renormalization-Group Fixed Points in the Hierarchical Approximation (1999)
    Springer
    Journal of statistical physics 95 (1999), S. 1-22 
    Details
    ISSN: 1572-9613
    Keywords: renormalization group ; fixed points ; cubic invariance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We compute renormalization-group fixed points and their spectrum in an ultralocal approximation. We study a case of two competing nontrivial fixed points for a three-dimensional real N-component field: the O(N)-invariant fixed point vs. the cubic-invariant fixed point. We compute the critical value N c of the cubic φ 4-perturbation at the O(N)-fixed point. The O(N)-fixed point is stable under a cubic φ 4-perturbation below N c; above N c it is unstable. The Critical value comes out as 2.219435〈N c〈2.219436 in the ultralocal approximation. We also compute the critical value of N at the cubic invariant fixed point. Within the accuracy of our computations, the two values coincide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004568925547
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  • 4
    Electronic Resource
    Electronic Resource
    New syntheses of 2,4-diaminopyrroles and aminopyrrolinones (1997)
    Springer
    Monatshefte für Chemie 128 (1997), S. 933-943 
    Details
    ISSN: 1434-4475
    Keywords: Thorpe-Ziegler cyclization ; (Oxazolin-2-yliden)malononitrile ; 2,4-Diamino-pyrrole ; 2-Amino-4-oxo-pyrrol-3-carbonitrile ; 4-Amino-2-oxo-pyrrol-3-carbonitrile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Oxazolin-2-yliden-malononitrile3a–d. die aus Thioketenaminalen und α-Halogenketonen erhalten wurden, reagieren mit primären und sekundären Aminen zu den 2,4-Diaminopyrrolen5a–h. Mercaptobenzol als nukleophiles Reagens liefert 4-Amino-2-phenylthiopyrrol (5j). Analog wurden Cyan-(3,5-diphenyl-3H-oxazol-2-yliden)-essigsäuremethylester als Zwischenprodukte für die Synthese der 2-Amino-4-oxo-pyrroline10a–d hergestellt. Die isomeren 4-Amino-2-oxo-pyrroline13a–d können aus den 4-Amino-2-methoxy-pyrrolen11a,b erhalten werden, was als Nachweis für die Position der Substituenten dient. Die Verbindungen wurden1H- und13C NMR-spektroskopisch untersucht.
    Notes: Summary Oxazolin-2-ylidene-malononitriles3a–d, obtainable from thioketenaminals and α-halogen-ketones, react with primary and secondary amines to afford 2,4-diamino-pyrroles5a–h. Mercaptobenzen as nucleophilic agent gives the 4-amino-2-phenylthio-pyrrole5j. Analogously, cyano-(3,5-diphenyl-3H-oxazol-2-ylidene)-acetic acid methyl esters were prepared as intermediates for the synthesis of 2-amino-4-oxo-pyrrolines10a–d. The isomeric 4-amino-2-oxo-pyrrolines13a–d can be obtained from 4-amino-2-methoxy-pyrroles, which serves as proof for the position of substituents. The structures were investigated by1H and13C NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807103
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  • 5
    Electronic Resource
    Electronic Resource
    Darstellung und Reaktionen von 2-Mercapto-6-thioxo-thiopyran-3-carbonsäure-Derivaten (1996)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 516-522 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Reactions of 2-Mercapto-6-thioxo-thiopyran-3-carboxylate derivatives6-Amino-thiopyran-2-thiones (1) react with dihydrogen sulfide in the presence of pyridine and triethyl amine to yield 6-thioxo-thiopyran-2-thiolates (2). Methylation of 2 gives the methylthio compounds 3 and 4. Further methylation of 3a and 4a yields the thiapyrylium salt (7). The reaction of 2-imino-thiopyran (6) with carbon disulfide represents another route to the 6-methylthio-thiopyran-2-thione (4a). The 2-methylthio-thiopyran-6-thione (3a) undergoes substitution of the methylthio group with amines to 8 or reacts with phenylhydrazine to phenylhydrazono-thiopyrane (9c). 6-Thioxo-thiophen-2-thiolates (2a,b) react with hydrazine hydrate to give hydrazono-thiopyranes (10a,b) which can be S-methylated. On the contrary 2c gives with hydrazine hydrate under ring transformation the pyridine-2-thiolate (11). N,S-Acetals (12) and 1,3,4-thiadiazoles (15), which give rise to new pyridine derivatives (14) and (17), can be obtained from 1-Amino-pyridin-2-thiolate (11).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19963380198
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