Synthesis and Reactions of the Novel 6‐ethyl‐4‐hydroxy‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde

Abstract

The novel 6‐ethyl‐4‐hydroxy‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde (2) was efficiently synthesized from Vilsmeier–Haack formylation of 3‐(1‐ethy1‐4‐hydroxy‐2‐oxo‐(1H)‐quinolin‐3‐yl)‐3‐oxopropanoic acid (1). The aldehyde 2 was allowed to react with some nitrogen nucleophiles producing a variety of hydrazones 3–7. Reaction of aldehyde 2 with hydrazine hydrate and hydroxylamine hydrochloride afforded pyrazole and isoxazole annulated pyrano[3,2‐c]quinoline‐2,5(6H)‐dione, respectively. The reactivity of aldehyde 2 was examined toward some active methylene nitrile, namely, malononitrile, ethyl cyanoacetate, and cyanoacetamide leading to 2‐iminopyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines 10–12, respectively. Also, some novel pyrazolo[4″,3″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines (13, 14) and thiazolo[5″,4″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines (15, 16) were synthesized. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.

Synthesis and biological evaluation of novel 2‐arylquinoline‐3‐fused thiazolo[2,3‐c]1,2,4‐triazole heterocycles as potential antiproliferative and antimicrobial agents

“…Later, 2-chloroquinoline-3-carbaldehyde 2 was treated with variety of aryl boronic acids 3a-e in the presence of Pd(PPh 3 ) 4 catalyst using Na 2 CO 3 as a base and Toluene: EtOH (3:2) as a solvent under reflux for 4h to afford 2-arylquinoline-3-carbaldehyde 4a-e in 90 to 95% yield [25][26][27]. Compound 4a-e was then treated with thiosemicarbazide 5 to obtain 2-aryl quinoline based oxime 6a-e in high yield [28]. The 2-arylquinoline-3-semicarbazide 6a-e compound was then reacted with different phenacyl bromides 7a-f to get thiazole based 2-arylqunoline intermediates 8a-t [29][30][31][32].…”