Substituted Pyridopyrimidinones. Part 3. Synthesis of Some Novel Ether Derivatives of 4H-Pyrido[1,2-a]pyrimidin-4-one

Abstract

A series of novel bis-heterocyclic ethers, containing 4Hpyrido[1,2-a]pyrimidin-4-one along with other five and six-membered heterocyclic rings, was obtained utilizing ethyl [(4-oxo-4Hpyrido[1,2-a]pyrimidin-2-yl)oxy]acetate (1), [(4-oxo-4H-pyrido[1,2a]pyrimidin-2-yl)oxy]acetic acid (2) and/or [(4-oxo-4H-pyrido[1,2a]pyrimidin-2-yl)oxy]acetohydrazide (3). Reaction of ester 1 with some ortho-hydroxy-aldehydes furnished the corresponding pyridopyrimidyloxypyrones. Reaction of ester 1 or acid 2 with 1,2-diamines led to some imidazoles. Also, some pyrazole, triazole, and oxadiazoline derivatives have been prepared from hydrazide 3.

Facile Reagent‐Free Synthesis of Furo[3,2‐c]pyridinones and Their Polynuclear Analogues with DDQ as Precursor

“…Next, we attended to further enlarge the substrate scope of this oxidative annulation protocol to synthesize polynuclear furan‐fused pyrido[1,2‐ a ]pyrimidine bases. The structural pattern of pyrido[1,2‐ a ]pyrimidin‐4‐ones has found its presence in biologically active molecules just like Ramastine, Risperidone, Paliperidone and SSR69071 . The efficient synthesis of the tricyclic pyrimidine derivatives, furo[2,3‐ d ]pyrido[1,2‐ a ]pyrimidines, has been less explored to date …”

“…The structural pattern of pyrido[1,2‐ a ]pyrimidin‐4‐ones has found its presence in biologically active molecules just like Ramastine, Risperidone, Paliperidone and SSR69071 . The efficient synthesis of the tricyclic pyrimidine derivatives, furo[2,3‐ d ]pyrido[1,2‐ a ]pyrimidines, has been less explored to date The precursors 5a ‐ d used in this transformation can be readily prepared through the thermal condensation of 2‐aminopyridine or analogues with malonate .…”

Synthesis, Characterization, and Biological Evaluation of Some Novel Quinoxaline Derivatives as Antiviral Agents

“…The starting compounds ethyl (6,7‐dimethyl‐3‐oxo‐3,4‐dihydroquinoxalin‐2‐yl)acetate and ethyl (7‐methyl‐3‐oxo‐3,4‐dihydroquinoxalin‐2‐yl)acetate ( 1a , b ) were synthesized according to the reported work . Thermal cyclocondensation of oxyacetic acid derivative with thiocarbodihydrazide was carried out on neat . Also, successful cyclocondensation through the utility of NaOH plates was reported .…”

Synthesis and Chemical Reactivity of the Novel 4‐Hydroxy‐6‐methyl‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde

“…Heating N ‐methylaniline with two equivalent diethylmalonate gave 4‐hydroxy‐6‐methyl‐2 H ‐pyrano[3,2‐ c ]quinoline‐2,5(6 H )‐dione ( 1 ) in one‐pot double cyclocondensation process . Warming pyranoquinoline‐2,5(6 H )‐dione 1 in sodium hydroxide solution (1 N) at 40–50°C for 30 min afforded 3‐(4‐hydroxy‐1‐methy1‐2‐oxo‐(1 H )‐quinolin‐3‐yl)‐3‐oxo‐propanoic acid ( 2 ) (Scheme ) . Following our interest on the chemistry of pyrano[3,2‐ c ]quinolinones , herein, we report the synthesis of the novel 4‐hydroxy‐6‐methyl‐2,5‐dioxo‐5,6‐dihydro‐2 H ‐pyrano[3,2‐ c ]quinoline‐3‐carboxaldehyde ( 4 ) as starting material and explored its chemical reactivity towards a variety of nitrogen nucleophilic reagents hoping to construct a novel series of substituted pyrano[3,2‐ c ]quinoline‐2,5(6 H )‐dione of potential biological activity.…”