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  • 1
    ISSN: 0170-2041
    Keywords: Thionation ; Rearrangement, translocative ; Cyclodehydrosulfurization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ringöffnungs-Reaktionen mesoionischer [1,2,4]Triazolo[1,5-c]-chinazoline. - Synthese von 1,2,4-Triazolo[3,4-b][1,3,4]thiadiazolen durch Umlagerung mit Thioacylgruppen-ÜbertragungMesoionische 1-Amino-5-aryl-2-mercapto-1H-[1,2,4]-triazolo-[1,5-c]chinazolin-4-ium hydroxide (1) lassen sich mit Salzsäure unter Ringöffnung in 4-Amino-3-[2-(aroylamino)phenyl]-4,5-dihydro-5-thioxo-1H-1,2,4-triazole 3 überführen. Umsetzung von 3 mit Phosphorpentasulfid liefert die entsprechenden 1,2,4-triazolo-[3,4-b][1,3,4]thiadiazole 6. Die Struktur von 6b wurde mittels Röntgenstrukturanalyse bestimmt.
    Notes: 1-Amino-5-aryl-2-mercapto-1H[1,2,4]triazolo[1,5-c]quinazolin-4-ium hydroxides, inner salts (1) undergo ring opening by the action of hydrochloric acid to give 4-amino-3-[2-(aroylamino)-phenyl]-4,5-dihydro-5-thioxo-1H-1,2,4-triazoles 3. Reaction of compounds 3 with phosphorus pentasulfide yields the corresponding 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles 6. The molecular structure of 6b has been solved by X-ray diffraction methods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Herstellung 2-substituierter 1,3,4-Thiadiazole und mesoionischer 1,3,4-Thiadiazol[3,2-c]chinazoline aus 4H-3,1-Benzothiazin-4-thionen oder 3-Amino-4(3H)-chinazolinthionen4H-3,1-Benzothiazin-4-thione vom Typ 1 reagieren mit S-Methyl-isothiosemicarbazid-hydroiodid zu 2-Amino-1,3,4-thiadiazolen 2 an Stelle der erwarteten 1,2,4-Triazolo[3,2-c]chinazoline. Die Strukturaufklärung von 2 gelang durch Röntgenstrukturanalyse und 13C-NMR-Spektroskopie. Die 3-Amino-4(3H)-chinazolin-thione 4 reagieren mit Keten-dithioacetalen 5 zu neuartigen mesoionischen 1,3,4-Thiadiazolo[3,2-c]chinazolinylium-2-methaniden 6. Letztere erleiden Ringöffnung durch Salzsäure unter Bildung von 2-Methylen-1,3,4-thiadiazolen 7. Die Verbindungen 2 lassen sich durch Behandlung mit Salzsäure in die entsprechenden O-Analoga 9 umwandeln.
    Notes: Reaction of 4H-3,1-benzothiazine-4-thiones 1 with S-methylisothiosemicarbazide hydroiodide yields 2-amino-1,3,4-thiadiazoles 2 instead of the expected 1,2,4-triazolo[3,2-c]quinazolines. Structures of compounds 2 have been established by means of 13C-NMR analysis and X-ray crystallography. 3-Amino-4(3H)-quinazolinethiones 4 react with ketene dithioacetals 5 to give the new mesoionic 1,3,4-thiadiazolo[3,2-c]quinazolinylium-2-methanides 6 which undergo ring opening by the action of hydrochloric acid to give 2-methylene-1,3,4-thiadiazoles 7. Compounds 2 are converted into the corresponding oxygen analog 9 by treatment with hydrochloric acid.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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