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  • 1
    ISSN: 1434-4475
    Keywords: Chloroformate ; Chloro(di)thioformate acylation ; 5-Amino-1,2,3,4-thiatriazole ; Trithiadiazapentalenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die durch Pyridine katalysierte Acylierung von 5-Amino-1,2,3,4-thiatriazol mit Chlorameisensäureethylester führt zu 3,5-bis-(ethoxycarbonylamino)-1,2,4-thiadiazolen, während mit Chlorthioameisensäureethylester 2,5-bis(phenoxy)-1,6,6a,Δ4-trithia-3,4-diazapentalene erhalten werden. Ohne Pyridin entsteht bei letzterer Reaktion ein wenig stabiles, aber isolierbares Zwischenprodukt: 2-Phenoxy-1-aza-3,4-dithiolium-5-imid. Die Bis(phenoxy)trithiadiazapentalene reagieren leicht mit nukleophilen Reagenzien und tauschen dabei schrittweise eine oder beide Phenoxygruppen aus.
    Notes: Summary Pyridine catalyzed acylation of 5-amino-1,2,3,4-thiatriazole with chloroformates and chlorothioformates afforded 3,5-bis(ethoxycarbonylamino)-1,2,4-thiadiazoles in the former and 2,5-bis(phenoxy)-1,6,6a,Δ4-trithia-3,4-diazapentalenes in the latter case. An unstable, but isolable intermediate 2-phenoxy-1-aza-3,4-dithiolium-5-imide has been found if the chlorothioformate acylation was performed in acetonitrile in the absence of pyridine. The bis(phenoxy)trithiapentalenes are prone to nucleophilic displacement reactions at positions 2 and 5, exchanging in a stepwise manner one or both phenoxy groups. The structures of the compounds described could be inferred from their1H-NMR13C-NMR, and mass spectra and were corroborated by the comparison with the data of authentic and similar derivatives as well as by chemical means.
    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 329 (1987), S. 409-416 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On Alkylation and Acylation of 5-Hydrazino-1,2,3,4-thiatriazole Derivatives5-Hydrazino-1,2,3,4-thiatriazole reacts with oxo carboxylic acids to give highly unstable 5-carboxyalkylidene-hydrazino-1,2,3,4-thiatriazoles (2). The more stable 5-alkylidenehydrazino-1,2,3,4-thiatriazoles (3) may be alkylated; the thiatriazole system is retained. On action of activated nitriles or isocyanates 1,2,4-thiadiazole (6) or 1,2,4-thiadiazoline derivatives (7) are formed with nitrogen evolution. At temperatures above 40°C, the described thiatriazoles decomposed to give undefinable components.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acylation of Heterocycles with Carbonic Acid Derivatives. II. Endo and Exo Carbamoylation of 2-Amino-benzimidazole Derivatives with Isocyanates. Mechanism of the Acyl Group Migration2-Amino-benzimidazoles react with isocyanates with good yields to give 2-amino-1-carbamoyl-aminobenzimidazoles 1 at -30°C and the corresponding 2-carbamoyl isomeres 2 at room temperature, respectively. The isomerization mechanism was studied by crossover experiments and kinetic measurements and has been found to consist of inter- and monomolecular acyl transfer.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acylation of Heterocycles with Carbonic Acid Derivatives. I. Kinetics and Mechanism of the Reaction of 2-Aminobenzimidazoles with Aryl CyanatesThe second order rate constants for the reaction of 2-amino-benzimidazoles (2-ABI) with aryl cyanates forming 2-amino-benzimidazole aryl ester imide 3 have been determined in dependence on substituent effects by u. v. measurements. The results are interpreted by a six-membered cyclic transition state in which the electrophilic attack of the cyanate on the endocyclic N atom is catalyzed by an H bridge interaction of the exocyclic amino group of 2-ABI with the OCN group.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 515-521 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: About the Reactions of Benzimidazole-2-carbohydrazide with Electrophilic CompoundsBenzimidazole-2-carbohydrazide (1) reacts with aldehydes and ketones to form N-alkylidene-benzimidazole-2-carbohydrazides(2a-j). With carbon disulfide, diphenyl carbonate and cyanates, ring closure takes place to afford 1,2,4-triazines and 1,3,4-oxadiazoles. Attempts to synthezise 2-isocyanato-benzimidazole failed.1H-n.m.r. and 13C-n.m.r. spectroscopic data of the compounds are given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 534-537 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Cryptands with 1,3,5-Triazines as Ring Building BlocksThe synthesis and characterization of 10 new cryptands 5a-j, containing two 1,3,5-triazine rings as subunits are described. The general methodology used is based on the aminolysis of cyanuric chloride with α,ω-diamino compounds or diazacrowns.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 316 (1974), S. 886-894 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Aryliden-pyrazolidon-(3)-azomethinimine 5 lagern sich in protonischen Lösungsmitteln quantitativ in 1-substituierte 3-Hydroxy-pyrazole 2 um. Damit steht erstmalig eine einfache allgemeine Synthese für 2 zur Verfügung. IR- und 1H-NMR-Parameter, deren Signifikanz durch eindeutig synthetisierte 1-substituierte 3-Hydroxy-pyrazole 2 belegt ist, beweisen die Struktur der 3-Hydoxy-pyrazole 2.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 321 (1979), S. 379-386 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanic Acid Esters. 27. Triazino-benzimidazoles from 2-Amino-benzimidazole-1-imid-esters and Carbonyl Analogic CompoundsThe Cyclocondensation of 2-amino-benzimidazole-1-imid-esters with aldehydes, carbonic acid anhydrides and isocyanates has been investigated. With aldehydes in the presence of piperidine 4-aryloxy-1,2-dihydro-1,3,5-triazino[1,2-a]benzimidazoles 3 and with carbonic acid anhydrides 4-aryloxy-1,3,5-triazino[1,2-a]benzimidazoles 5 are formed. Isocyanates react with the imid esters to the corresponding 3-substituted ureas 8 which on heating undergo acyl migration of the carbamoyl group followed by cyclocondensation to 4-imino-2-oxo-1,2,3,4-tetrahydro-1,3,5-triazino[1,2-a]benzimidazoles 12.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 585-588 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acyl Migrations on 3(5)-Amino-pyrazole3(5)-Amino-pyrazole 1 form 3 isomeric monoacylation products, 4 diacylation products and 3 triacylation products by reaction with electrophiles like cyanates, isocyanates or carboxylic and chlorides, respectively. Acyl migrations are observed depending on the reaction temperature and the structure of the acyl residue. The structures of the acyl derivatives of 3(5)-amino-pyrazole were characterized by nmr-spectroscopy.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 318 (1976), S. 253-260 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: General Synthesis of 1-Substituted Pyrazolidine-3-ones by Nucleophilic Grignard Addition at Carbonyl-stabilized AzomethiniminesBy means of Grignard compounds in THF the nucleophilic addition of alkyl, aralkyl or aryl groups at the C-6 atom of carbonyl-stabilized azomethinimines 1 is achieved. This new general synthesis gives high yields of 1-substituted pyrazolidine-3-ones 8. The C-6-substitution is proved by unambiguous syntheses and by 1H-n.m.r. C-4-Substituted azomethinimines 1 and Grignard compounds give mixtures of diastereomeric 1-substituted pyrazolidine-3-ones 8, as indicated by their 1H- and 13C-n.m.r. spectra. The Grignard addition is thus shown to proceed not stereospecifically.
    Notes: An das C-6-Atom carbonylstabilisierter Azomethinimine 1 lassen sich Alkyl-, Aralkyl- oder Arylreste mit Hilfe von Grignard-Verbindungen in THF nucleophil addieren. Diese neue, allgemeine Synthese 1-substituierter Pyrazolidone-(3) 8 verläuft mit hoher Ausbeute. Die C-6-Substitution wird durch eindeutige Synthesen und NMR-spektroskopisch bewiesen. Die Grignard-Addition verläuft, wie an der NMR-spektroskopisch nachgewiesenen Bildung von diastereomeren 1-substituierten Pyrazolidonen-(3) 8 aus C-4-substituierten 1 gezeigt wird, nicht stereospezifisch.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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