Green Synthesis of Dihydropyrimido[4,5‐b]quinolinetriones by Sulfonic Acid‐Functionalized Silica‐Coated CoFe₂O₄ as a Solid Acid Nanocatalyst under Thermal and Ultrasonic Conditions

Abstract

Sulfonic acid functionalized silica coated cobalt ferrite nanoparticles (CoFe2O4/SiO2−SO3H) was prepared as an efficient solid acid catalyst for the green synthesis of dihydropyrimido[4,5‐b]quinolinetrione derivatives. CoFe2O4 NPs were prepared by co‐precipitation method and then the silica‐coated CoFe2O4 NPs were modified with chlorosulfonic acid. Obtained CoFe2O4/SiO2−SO3H was characterized by thermo gravimetric analysis (TGA), Fourier transform‐infrared spectroscopy (FT‐IR), scanning electron microscope (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD) and vibrating‐sample magnetometer (VSM). The magnetically separable CoFe2O4/SiO2−SO3H was successfully used for the four component reaction of barbituric acid, dimedone, amines (or ammonium acetate) and benzaldehyde derivatives for the synthesis of dihydropyrimido[4,5‐b]quinolinetriones under thermal and ultrasound conditions. The advantages of presented simple protocol are the easily separation of magnetic catalyst from the reaction medium by an external magnet, short reaction times, green reaction conditions in addition to simple workup and high yield of products.

Synthesis of Nitrogen- and Oxygen-Containing Heterocycles Catalysed by Metal Nanoparticles Reported in 2022

“…BET revealed the dimension of MNPs in the range of (83), ammonium acetate (95), different aldehydes (88) and ethyl acetoacetate (154), catalysed via the Hantzsch reaction with ethanol as the solvent in excellent yields (91-95%).The catalyst retained its activity for five successive runs. The authors reported the successful synthesis of quinazolines using substituted benzaldehyde, dimedone, and urea using the same catalysts in ethanol at 60 102 Sulfonic acid functionalised silicacoated CoFe 2 O 4 NPs were synthesised using the co-precipitation method, and then altered with chlorosulfonic acid. The catalyst retained its efficiency for five cycles without any significant changes.…”

Recent progress of nanocatalyst in the synthesis of heterocyclic compounds by barbituric acids

“…The main benefits of this method are quick isolation by a magnet, easy usage, reduced reaction times with excellent efficiency, and green reaction status. In the presented method, at first, the CoCl 50 According to the proposed mechanism shown in Scheme 6, at first, solid acid CoFe 2 O 4 /SiO 2 -SO 3 H activated the C=O group of aldehydes 2, then the F I G U R E 2 Some structures of heterocyclic compounds with biological applications. [20][21][22][23][24][25] S C H E M E 1 The general synthetic route of pyranopyrimidines 4 using Fe 3 O 4 @GO-NH 2 .…”

“…[20][21][22][23][24][25] S C H E M E 1 The general synthetic route of pyranopyrimidines 4 using Fe 3 O 4 @GO-NH 2 . 50 Rostami and Shiri also reported CoFe 2 O 4 @SiO 2 -PA-CC-guanidine MNPs for synthesizing pyrazolopyranopyrimidines 17 by BA 1, aryl aldehyde 2, hydrazine hydrate 15, and ethyl acetoacetate (EAA, 16) as reactants in green solvent water (Scheme 7). This process in the presence of CoFe 2 O 4 @SiO 2 -PA-CC-guanidine MNPs offers some merits like the use of recyclable and safe nanocatalysts, green solvents, excellent yields, short reaction period, and simple work-up.…”

“…Then magnetically separable CoFe 2 O 4 /SiO 2 ‐SO 3 H was obtained by modification of CoFe 2 O 4 /SiO 2 with chlorosulfuric acid (Scheme 5). 50 …”

“…Afterward, dimedone nucleophilically attacks intermediate 11 to form intermediate 12 and remove water by intramolecular cyclization to give intermediate 13 . Lastly, via ring opening process and other intramolecular ring closure followed by water elimination, the –NH 2 undergoes Nu attack on intermediate 14 to form the related products 10 50 …”