SYNTHIESIS OF PYRAZOLO (3,4-b)QUINOLINES AND THEIR 1-PHENYL DERIVATIVES

Synthesis of Tetrazoloquinoline‐Based Mono‐ and Bisphosphonate Esters as Potent Anti‐Inflammatory Agents

“…The presence of quinolines in an abundant number of natural products and pharmaceutically active compounds continues to fuel the desire to develop new and/or improved methods for their synthesis . Many representatives have found clinical uses for the treatment of tumor diseases . There have also been reviews on quinoline derivatives and their antibiotic properties in multidrug resistant Enterbacter aerogenes isolates .…”

Novel Bisphosphonates Derived from 1H‐Indazole, 1H‐Pyrazolo[3,4‐b]Pyridine, and 1H‐Pyrazolo[3,4‐b]Quinoline

“…1H-Pyrazolo [3,4-b]pyridine 2 [30], 1H-pyrazolo [3,4b]quinoline 3 [31] and tetraethyl ethenylidene-1,1bisphosphonate 4 [32] were prepared according to literature procedures. 1H-Pyrazolo [3,4-b]pyridine 2 [30], 1H-pyrazolo [3,4b]quinoline 3 [31] and tetraethyl ethenylidene-1,1bisphosphonate 4 [32] were prepared according to literature procedures.…”

“…The synthesis of 1H-pyrazolo[3,4-b]pyridine 2 and 1H-pyrazolo [3,4-b]quinoline 3 was performed in high yields, by a reaction of 2-chloro-3formylpyridine or 2-chloro-3-formylquinoline and hydrazine with p-TsOH using a process reported in the literature [30,31]. Tetraethyl ethylidene-1,1bisphosphonate 4 was obtained from tetraethyl methylenebisphosphonate in two steps, according to a literature procedure [32].…”

Efficient syntheses of 1,3-unsubstituted 1H-pyrazolo[3,4-b]quinolines

“…Thus, although some hetarylhydrazines were described as reacting with 6-bromo-31 or 7-methoxy-32 -2-chloro-3-formylquinolines in methanol at reflux or with microwave heating, other reports of attempts to bring about such cyclocondensations implied difficulties. It was shown 28 for example, that an Ehydrazone is formed from such chloro-aldehydes which would not ring-close in refluxing ethanol, having the inappropriate imine geometry, however other workers apparently did not encounter such difficulties using hydrazine hydrochlorides in refluxing ethanol for extended reaction times, 33 or reflux in acetonitrile. 34 Much more vigorous conditions can be applied to the interaction between 2-chloro-3-formylquinolines and hydrazine and arylhydrazines which overcome these difficulties: microwave heating with p-toluenesulfonic acid is recommended.…”