Fused quinoline heterocycles V. Synthesis of novel 1,2,3,5,6-pentaazaaceanthrylene derivatives

A Novel Synthesis of 1‐Aryl‐6‐bromo‐3‐(5‐ethylthio‐4‐phenyl‐4H‐1,2,4‐triazol‐3‐yl)‐1H‐pyrazolo[4,3‐b]quinolin‐9(4H)‐ones via Thermal Cyclization of 4‐Azidopyrazoles

“…Nevertheless, among the isomeric pyrazolo[3,4‐ b ]quinolines, effective optical bleaches and substance possessing a broad spectrum of biological activity have been found. Prompted by the a foresaid biological and pharmaceutical activities and in continuation of our previous work aimed at developing new, simple and efficient approaches for the synthesis of poly functionally substituted heterocycles containing pyrazole or 1,2,4‐triazole nucleus with potential biological activity , we now present the first synthetic entry to the novel pyrazolo[4,3‐ b ]quinolin‐9‐ones via thermal cyclization of 4‐azidopyrazoles. To the best of our knowledge, no similar strategy for the synthesis of pyrazolo[4,3‐ b ]quinolin‐9‐one skeleton has previously been reported.…”