Synthesis of New Pyrazolo[3,4‐b]quinolines, Thieno[2,3‐b]quinolines and Related Condensed Heterocyclic Systems

Abstract

3‐Amino‐1H‐pyrazolo[3,4‐b]quinoline (2) was reacted with benzaldehyde, acetylacetone, ethylacetoacetate and/or phenyl isothiocyanate to give compounds 3,4,5 and 6, respectively. The interaction of 6 with some α‐haloesters and/or α‐haloketones produced the corresponding thiazolidinones 7a‐c and thiazolines 9a‐d. 1H‐Pyrazolo[3,4‐b]quinoline‐3‐diazonium chloride (11) was coupled with some active methylene compounds to give the corresponding hydrazono compounds 12a,b and 13 which, in turn were cyclized into the corresponding triazinopyrazoloquinolines 14a,b and 15 by heating in acetic acid. 3‐Aminothieno[2,3‐b] quinoline‐2‐carbohydrazide (19) and 3‐amino‐2‐(1H‐benzimidazol‐2‐yl)thieno[2,3‐b]quinoline (21) were prepared and employed as key intermediates for synthesizing the second class of the title compounds.

IND-2, a pyrimido[1″,2″:1,5]pyrazolo[3,4-b]quinoline derivative, circumvents multi-drug resistance and causes apoptosis in colon cancer cells

“…2-Chloroquinoline-3-carbaldehyde, on treatment with hydroxylamine hydrochloride in aqueous ammonia in presence of cerric ammonium nitrate, furnished 2-chloroquinoline-3-carbonitrile ( 2 ) [20], which, on reaction with hydrazine hydrate under reflux conditions, afforded 1H-pyrazolo[3,4-b]quinolin-3-amine ( 3 ) [21]. 1H-Pyrazolo[3,4-b]quinolin-3-amine, refluxed in ethanol with ethyl acetoacetate, underwent a cyclo-condensation reaction to give 2-methylpyrimido[1”,2”:1,5]pyrazolo[3,4-b]quinoline-4(1H)-one ( IND-1 ) [22]. This was further halogenated with phosphorous oxychloride to give the key intermediate, 4-chloro, 2-methyl pyrimido[1”,2”:1,5]pyrazolo[3,4-b]quinoline ( IND-2 ), which, on reaction with appropriate alkyl amines in ethanol, gave the corresponding amino-alkyl substituted 2-methylpyrimido[1”,2”:1,5]pyrazolo[3,4-b]quinoline derivatives ( IND-3 to IND-8 ).…”

A new sensor based on thieno[2,3‐b]quinoline for the detection of In3+, Fe3+ and F− by different fluorescence behaviour

“…Compounds 2, 3, and 4 were prepared according to methods already reported in the literature. [ 39–41 ]…”

An Efficient Synthesis of 1′,7′,8′,9′‐Tetrahydrospiro[indoline‐3,4′‐pyrazolo[3,4‐b]quinoline]‐2,5′(6′H)‐dione Derivatives in Aqueous Medium

“…Pyrazole and its derivatives are the important compounds in medicinal and organic chemistry because of their broad spectrum of pharmacological and biological activities, such as anti‐bacterial, anti‐depressant, and anti‐hyperglycemic activity . Pyrazolo[3,4‐ b ]quinoline is a typical derivative of pyrazole, which has displayed the various bioactivities . In addition, pyrazolo[3,4‐ b ]quinoline is also the important luminescent material, which has important applications in the optical fields .…”