Synthesis of Some Thiazole‐, 1,3,4‐Thiadiazole‐, and 4H‐1,2,4‐Triazole Derivatives of Pyrazolo[3,4‐b]quinoline

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Abstract
Three novel series of pyrazolo[3,4‐b]quinolines were prepared, namely: 1‐(3‐substituted‐4‐phenylthiazolin‐2‐ylidene)hydrazinocarbonylmethyl‐1H‐pyrazolo[3,4‐b]quinolines 3a‐d; 1‐(5‐substituted amino‐1,3,4‐thiadiazol‐2‐yl)methyl‐1H‐pyrazolo[3,4‐b]quinolines 4b‐d, and 1‐(4‐substituted‐4H‐5‐thioxo‐1,2,4‐triazole‐3‐yl)methyl‐1H‐pyrazolo[3,4‐b]quinolines 5a‐d. These compounds were prepared by cyclization of the new key intermediates 1‐(substituted thiocarbamoylhydrazinocarbonyl)methyl‐1H‐pyrazolo[3,4‐b]quinolines 2a‐d. The alkylthio, aralkylthio 6a‐f as well as the Mannich bases 8a‐f derived from compounds 5a‐d were also prepared. The structures of the new compounds were elucidated by elemental analyses, IR, 1H‐NMR‐, and mass spectra. The antimicrobial as well as inotropic and chronotropic activities were studied. Synthese von neuen Thiazol‐, 1,3,4‐Thiadiazol‐ und 4H‐1,2,4‐Triazol‐Derivaten des 1H‐Pyrazolo[3,4‐b]chinolins Drei neue Serien von Pyrazolo[3,4‐b]chinolinen wurden hergestellt, nämlich: 1‐(3‐substituierte‐4‐Phenylthiazolin‐2‐yliden)hydrazinocarbonylmethyl‐1H‐pyrazolo[3,4‐d]chinoline 3a‐d; 1‐(5‐substituierte Amino‐1,3,4‐thiadiazol‐2‐yl)methyl‐1H‐pyrazolo[3,4‐b]chinoline 4b‐d und 1‐(4‐substituierte‐4H‐5‐thiono‐1,2,4‐triazole‐3‐yl)methyl‐1H‐pyrazolo[3,4‐b]chinoline 5a‐d. Diese Verbindungen waren durch Cyclisierung der neuen Schlüsselprodukte, der 1‐(substituierten Thiocarbamoylhydrazinocarbonyl)methyl‐1H‐pyrazolo[3,4‐b]chinoline 2a‐d zugänglich. Die Alkylthio‐, Aralkylthio‐Verbindungen 6a‐f und die Mannich‐Basen 8a‐f, die alle von den Verbindungen 5a‐d abstammen, wurden auch synthetisiert. Die Strukturen der neuen Verbindungen wurden durch Elementaranalyse, IR‐, 1H‐NMR‐ und Massenspektren bestimmt. Die antimikrobielle, inotropische und chronotropische Aktivität wurden geprüft.

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