An Efficient New Route for the Synthesis of Some 3‐Hterocyclylquinolinones via Novel 3‐(1,2‐Dihydro‐4‐hydroxy‐1‐methyl‐2‐oxoquinolin‐3‐yl)‐3‐oxopropanal and Their Antioxidant Screening

Abstract

3‐(4‐hydroxy‐1‐methylquinoline‐3‐yl)‐3‐oxoproponal (5) was synthesized from 3‐[(E)‐3‐(dimethylamino)‐2‐propenoyl]‐4‐hydroxy‐1‐methyl‐2(1H)‐quinolinone (3) and was utilized as a starting precursor material. A convenient new route to functionalized 3‐heterocyclyl 4‐hydroxy‐2(1H)‐quinolinones such as pyrazolyl, isoxazolyl, pyrimidinyl, azepineyl, pyridonyl, and pyranyl heterocycles was described via cyclization of compound 5 with some N and C‐nucleophiles. The newly synthesized aldehyde 5 showed only one ring closure possibility with maximum yield instead of using compound 3 that exhibited different regioselective ring closure routes with minimum yields. All newly synthesized products were structurally elucidated on the basis of their relevant spectroscopic data and elemental microanalyses. The antioxidant activity of the products was screened in a series of in vitro tests.

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

“…Moreover, aldehyde 2 was subjected to condensation reactions with some cyclic active methylene compounds. Thus, treatment of aldehyde 2 with 5‐methyl‐2,4‐dihydro‐3 H ‐pyrazol‐3‐one and 5‐phenyl‐2,4‐dihydro‐3 H ‐pyrazol‐3‐one, in glacial acetic acid containing freshly fused sodium acetate, afforded the corresponding pyrazolo[4″,3″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐ c ]quinolines 13 and 14 , respectively (Scheme ) . Compounds 13 and 14 were synthesized via condensation reaction between aldehyde and active methylene groups followed by cyclodehydration process.…”

Autoxidation of 4-Hydrazinylquinolin-2(1H)-one; Synthesis of Pyridazino[4,3-c:5,6-c′]diquinoline-6,7(5H,8H)-diones

“…Compounds with quinolin-2(1 H )-one (carbostyril) skeletons are present in a large number of biologically active compounds [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. During the twentieth century [ 13 ], various research groups dealt with the chemistry and biological applications of quinolines [ 14 ].…”

Synthesis and Antimicrobial Activity of Novel 4-Hydroxy-2-quinolone Analogs

“…In the search for a new scaffold for antimicrobial drugs, 4-hydroxy-2-quinolone, a class of heterocyclic compound, has shown great potential, as various analogs of 4-hydroxy-2-quinolone including Roquinimex (Linomide), a synthetic immunomodulator [ 3 ], have been reported to possess a wide range of biological activities such as antibacterial [ 4 ], antifungal [ 5 ], anticancer [ 6 ], antioxidant [ 7 ], and so on. Over the past few decades, several attempts have been made to investigate the structure–activity relationship of the antimicrobial activity of this scaffold; for instance, the derivatives of 4-hydroxy-2-quinolone bearing chalcones [ 8 ], pyrimidines [ 9 ], pyrazoles [ 10 ], and thiadiazole [ 11 ] ( Figure 1 a).…”