Synthesis and antimicrobial activity of 6,7-annulated pyrido[2,3-d]pyrimidines

Greener Approach for Synthesis of δ-MnO2 Nanoparticles: Access to Pharmaceutically Important Pyrimidines and their Antimicrobial Activity Studies

A sustainable approach for pharmaceutically important pyrimidine derivatives is achieved by using biogenically produced single-phase δ-MnO2 NPs under external ligand-free conditions. The phytochemicals that comprise the extract of Areca Nut Husk (ANH) have been discovered to serve as reducing agents. The role of phytochemicals is not only to aid in the reduction of Mn(VII) into Mn(IV), but they also have an important role in stabilizing the catalyst. The establishment of δ-MnO2 NPs was confirmed inveterate by FE-SEM, p-XRD, ICP-OES (Mn content = 43.17% w/w), EDX, and with an active Mn content of 43.17% w/w. A series of pyrimidine derivatives were prepared in good yields using a one-pot multicomponent synthesis approach under atmospheric conditions. In addition, hot filtration tests, control experiments, gram-scale synthesis, and mechanistic investigations were demonstrated. Additionally, antimicrobial activity studies of δ-MnO2 NPs and pyrimidine derivatives against the Gram-negative bacteria E. coli, growth curve and minimum inhibitory concentration were studied.

Immobilized Ni on TMEDA@βSiO2@αSiO2@Fe3O4: as a novel magnetic nanocatalyst for preparation of pyrido[2,3-d:6,5-d']dipyrimidines

In the current body of research, a very quick and effectual procedure for the synthesis of pyrido[2,3-d:6,5-d']dipyrimidines has been developed. This method is accomplished through the one-pot multi-component reaction of 2-thiobarbituric acid, NH₄OAc and aldehydes utilizing Ni-TMEDA@βSiO₂@αSiO₂@Fe₃O₄ as a novel mesoporous nanomagnetic catalyst at room temperature. This protocol is one of the few reports of the preparation of these derivatives without the use of conventional heating as well as energies such as microwave and ultrasound radiation. The characterization of the prepared catalyst was well accomplished by different techniques such as FT-IR, ICP-OES, SEM, TEM, BET, XRD, VSM, TGA, EDX and Elemental mapping. This organometallic catalyst was reusable for seven times with negligible decrement in its catalytic performance. In addition, all of the products were produced with high TON and TOF values, which demonstrates that our catalyst has a very high level of activity in the preparation of pyrido[2,3-d:6,5-d']dipyrimidines.

Cesium salt of 2-molybdo-10-tungstophosphoric acid as an efficient and reusable catalyst for the synthesis of uracil derivatives via a green route

A solid catalyst, cesium salt of 2-molybdo-10-tungstophosphoric acid (Cs_2.3H_0.7PW₁₀Mo₂O₄₀) named as Cs-3, was synthesized by a simple, cheap, clean, and eco-friendly method. The physicochemical properties of the synthesized catalyst were studied via FTIR spectroscopy, XRD, EDX, ICP-AES, SEM-TEM, and BET techniques. The precursor 2-molybdo-10-tungstophosphoric acid (H₃PW₁₀Mo₂O₄₀) was easily soluble in water and other polar solvents. Moreover, their cesium salts Cs _x H_3-x PW₁₀Mo₂ with Cs content in the range x = 2.0-2.5 were insoluble in water and other polar solvents. The surface area of the precursor (5.483 m² g^-1) increased after partial proton exchange by Cs⁺ ions (111.732 m² g^-1), and all samples with x > 1 were resistant to leaching of active components and can be recycled without obvious loss of activity. This catalyst used for the synthesis of uracil derivatives via a green route under solvent free conditions at 70 °C gives higher yield within a shorter reaction time. The catalyst was found to be more active and reusable over nine runs with a negligible loss of activity.

Tetrazol-Cu(i) immobilized on nickel ferrite catalyzed green synthesis of indenopyridopyrimidine derivatives in aqueous media

After the initial study of different protocols in the synthesis of indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidines, herein, a new method is presented using cheaper and more accessible starting materials to produce high-efficiency products. In this protocol, the novel nanocatalyst is very effective in the progression of the reaction and increasing the efficiency. This green approach in aqueous media has several advantages as compared with other methods, such as easier work-up, very mild reaction conditions, reusability of the catalyst, and eco-friendliness. The products of this four-component condensation were evaluated using IR, ¹H NMR, ¹³C NMR spectra, and C. H. N. analyses, and the catalyst structure was confirmed by FT-IR, XRD, SEM, EDX, TGA and VSM techniques.

In this protocol, a novel nanocatalyst was very effective in progression of the reaction and increasing efficiency. This green approach in aqueous media has several advantages compared with the reported methods.

Activated Carbon/MoO3: Efficient Catalyst for Green Synthesis of Chromeno[d]pyrimidinediones and Xanthenones

BACKGROUND

Nanoscale metal oxide catalysts have been extensively employed in organic reactions because they have been found to influence the chemical and physical properties of bulk material. The chromene (benzopyran) nucleus constitutes the core structure in a major class of many biologically active compounds, and interest in their chemistry consequently continues because of their numerous biological activities. The xanthene (dibenzopyran) derivatives are classified as highly significant compounds which display a number of various bioactive properties. Pyrimidinones have also gained interest due to their remarkable biological utilization, such as antiviral, antibacterial, antihypertensive, antitumor, and calcium blockers effects.

OBJECTIVE

The aim of this work presented herein was to prepare activated carbon/MoO3 nanocomposite and explore its role as a green and recyclable catalyst for the synthesis of chromeno[d]pyrimidinediones and xanthenones under ethanol-drop grinding at room temperature.

METHODS

The activated carbon/MoO3 nanocomposite was prepared successfully via a simple route in which the carbonization of gums as new natural precursors was used for the synthesis of activated carbon. This nanocomposite was then effectively used in a reaction of 3,4-methylenedioxyphenol, aromatic aldehydes, and active methylene compounds, including 1,3-dimethylbarbituric acid and dimedone, to synthesize a series of chromeno[d]pyrimidinediones and xanthenones in high yields. The synthesized catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), Powder x-ray diffractometry (XRD), Scanning electron microscope (SEM), Raman spectroscopy, and also by TGA analysis. Confirmation of the structures of compounds 5(a-g) and 6(a-g) were also established with IR, 1H NMR, and 13C NMR spectroscopic data and also by elemental analyses.

RESULTS

A number of 6,8-dimethyl-10-phenyl-6,10-dihydro-7H-[1,3]dioxolo[4´,5´:6,7]chromeno[2,3- d]pyrimidine-7,9(8H)-diones and 7,7-dimethyl-10-(4-methylphenyl)-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[ 4,5-b]xanthen-9-ones were effectively synthesized using activated carbon/MoO3 nanocomposite (0.05 gr) as a catalyst under ethanol-drop grinding at room temperature. The desired products were obtained in high yields (93-97%) within short reaction times (15-20 min).

CONCLUSION

This paper investigates the catalytic potential of the synthesized activated carbon/MoO3 nanocomposite for the preparation of chromeno[d]pyrimidinediones and xanthenones under the ethanol-drop grinding procedure. The mildness of the reaction conditions, high yields of products, short reaction times, experimental simplicity, and avoiding the use of harmful solvents or reagents makes this procedure preferable for the synthesis of these compounds.

Water mediated economical synthesis of chromeno[b]pyridin-3-yl cyanides using cadmium oxide nanoparticles as a highly efficient catalyst

A simple, practical, and economical protocol for the synthesis of a series of twelve 2-amino-5-oxo-4-aryl-5H-chromeno[4,3-b]pyridin-3-yl cyanides have been developed by the cyclocondensation reaction of 4-aminocoumarin, aromatic aldehydes, and malononirile in the presence of cadmium oxide nanoparticles (CdO NPs) as an cost-effective, reusable, and highly efficient heterogeneous catalyst in aqueous medium at 60 °C. The procedure is very simple, clean, mild, and practical for aromatic, as well as heteroaromatic, aldehydes without significant difference.

A PANI-Fe3O4@ZnO nanocomposite: a magnetically separable and applicable catalyst for the synthesis of chromeno-pyrido[d]pyrimidine derivatives

We report herein green, practical, PANI-Fe3O4@ZnO-nanocomposite-catalyzed cyclocondensation reactions involving 4-aminocoumarin, 1,3-dimethylbarbituric acid, and aromatic aldehydes in an aqueous medium at room temperature to synthesize 9,11-dimethyl-7-aryl-6H-chromeno[3',4':5,6]pyrido[2,3-d]pyrimidine-6,8,10(9H,11H)triones. This research aims to provide an applicable and high-yield protocol that follows the principles of green chemistry, with the use of water as an environmentally benign medium and the PANI-Fe3O4@ZnO nanocomposite as a magnetically recoverable catalyst.

In silico study combining QSAR, docking and molecular dynamics simulation on 2,4-disubstituted pyridopyrimidine derivatives

2,4-Disubstituted pyridopyrimidine derivatives were studied against ABCG2 enzyme. The modeling of pyridopyrimidine derivatives were done using two methods of multiple linear regression and support vector regression and four molecular descriptors of BIC4, log p, VRA2, and binding energy were selected for modeling. The statistical results were satisfactory. The interactions of ABCG2 enzyme with pyridopyrimidine derivatives were investigated using molecular docking method. Based on the results, increasing of binding energy and hydrophobicity of the compounds increase their inhibitory activity. Protein stability in complex with pharmaceutical derivatives was discussed using molecular dynamics simulation method.

Novel Brönsted Acidic Ionic Liquids Confined in UiO-66 Nanocages for the Synthesis of Dihydropyrido[2,3-d]Pyrimidine Derivatives under Solvent-Free Conditions

The effective and simple one-pot, three-component protocol for the synthesis of dihydropyrido[2,3-d]pyrimidine derivatives is presented using a triethylenediamine or imidazole Brönsted acidic, ionic-liquid-supported Zr metal-organic framework (TEDA/IMIZ-BAIL@UiO-66) as a green, novel, and retrievable heterogeneous catalyst under mild conditions. The multicomponent reactions of 6-amino-1,3-dimethyl uracil, various aromatic aldehydes, and acetyl acetone were conducted under solvent-free conditions so that dihydropyrido[2,3-d]pyrimidine derivatives can be obtained. It is possible to separate and purify the respective products easily using crystallization. We can recycle the catalysts six times without losing any major activity. Also, the characterization of the catalyst was done by energy-dispersive X-ray, field emission scanning electron microscopy, Fourier transform infrared, Brunauer-Emmett-Teller, X-ray diffraction, and thermogravimetric analysis analyses.

Regioselective synthesis of pyrimidine-fused tetrahydropyridines and pyridines by microwave-assisted one-pot reaction

A regioselective three-component reaction of α,β-unsaturated aldehydes, cyclic 1,3-dicarbonyls and 6-aminouracils in the presence of FeCl₃·6H₂O as catalyst under microwave irradiation has been demonstrated. Three-component reaction of α,β-unsaturated aldehydes like cinnamaldehyde/crotonaldehyde, cyclic 1,3-diketones such as 2-hydroxy-1,4-naphthaquinone/dimedone and 6-aminouracils provides regioselective pyrimidine-fused tetrahydropyridines tethered with cyclic 1,3-diketones. On the other hand, replacing cyclic 1,3-diketones by 4-hydroxycoumarin and keeping all other conditions the same provided a two-component pyrimidine-fused pyridines. The salient features of this methodology are operational simplicity, short reaction time, good-to-moderate yields of the products, easy purification method and regioselective products having medicinally important heterocyclic rings such as pyrimidine, tetrahydropyridine or pyridine.

Nano-2-(dimethylamino)-N-(silica-n-propyl)-N,N-dimethylethanaminium chloride as a novel basic catalyst for the efficient synthesis of pyrido[2,3-d:6,5-d′]dipyrimidines

A novel basic nanocatalyst has been synthesized, fully characterized, and applied to promote the efficient synthesis of pyrido[2,3-d:6,5-d′]dipyrimidines.

An expedient synthesis of 6-amino-5-[(4-hydroxy-2-oxo-2H-chromen-3-yl)(aryl)methyl]-1,3-dimethyl-2,4,6(1H,3H)-pyrimidinedione derivatives using Fe3O4@TiO2 nanocomposite as an efficient, magnetically separable, and reusable catalyst

An efficient methodology dealing with the Fe3O4@TiO2 nanocomposite-catalyzed direct condensation reaction of 4-hydroxycoumarin, aromatic aldehydes, and 6-amino-1,3-dimethyluracil in aqueous media at room temperature is reported. This new process has been successfully applied to the synthesis of 6-amino-5-[(4-hydroxy-2-oxo-2H-chromen-3-yl)(aryl)methyl]-1,3-dimethyl-2,4,6(1H,3H)-pyrimidinediones in high to excellent yields within 2–3 h.

Antibacterial activity of synthetic pyrido[2,3-d]pyrimidines armed with nitrile groups: POM analysis and identification of pharmacophore sites of nitriles as important pro-drugs

A pyrido[2,3-d]pyrimidine series has exhibited inhibitory effects on the growth of bacterial strains.

Synthesis, Antitumor Evaluation and Molecular Docking of New Morpholine Based Heterocycles

A series of new morpholinylchalcones was prepared and then used as building blocks for constructing a series of 7-morpholino-2-thioxo-2,3-dihydropyrido[2,3-d]pyrimidin-4(1H)-ones via their reaction with 6-aminothiouracil. The latter thiones reacted with the appropriate hydrazonoyl chloride to give the corresponding pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-ones. The assigned structures for all the newly synthesized compounds were confirmed on the basis of elemental analyses and spectral data and the mechanisms of their formation were also discussed. Most of the synthesized compounds were tested for in vitro activity against human lung cancer (A-549) and human hepatocellular carcinoma (HepG-2) cell lines compared with the employed standard antitumor drug (cisplatin) and the results revealed that compounds 8, 4e and 7b have promising activities against the A-549 cell line (IC₅₀ values of 2.78 ± 0.86 μg/mL, 5.37 ± 0.95 μg/mL and 5.70 ± 0.91 μg/mL, respectively) while compound 7b has promising activity against the HepG-2 cell lines (IC₅₀ = 3.54 ± 1.11 μg/mL). Moreover, computational studies using MOE 2014.09 software supported the biological activity results.

Efficient sonochemical green reaction of aldehyde, thiobarbituric acid and ammonium acetate using magnetically recyclable nanocatalyst in water

A facile one-pot and four-component economical synthesis of pyrido[2,3-d:6,5-d]dipyrimidines using aldehyde, 2-thiobarbituric acid and ammonium acetate in the presence of magnetically heterogeneous catalyst under ultrasonic irradiation in water is described. The present synthesis shows attractive characteristics such as; the use of magnetically recoverable and reusable catalyst, convenient one-pot operation, short reaction periods, high to excellent yields and the use of water as a green reaction medium, mild reaction conditions and is considered to be relatively environmentally benign.

One-pot synthesis of new Pyrido [2,3-d] Pyrimidine derivatives under ultrasonic irradiation using organo catalyst 4-Dimethylaminopyridine (DMAP)

The one-pot synthesis of pyrido[2,3-d] pyrimidine derivatives has been reported via Knoevenagel-Michal addition pathways using substituted aromatic aldehydes, Cyanoacetamide and 6-aminouracil in N,N-dimethylformamide (DMF) solvent, with 4-dimethylaminopyridine (DMAP) as new organo catalyst catalyst under ultrasonic irradiation. The results showed that a series of aromatic aldehydes were effectively used to prepare the targeted pyrido [2, 3-d] pyrimidine derivatives with good to excellent yields (81-93 %) with no major effect on the yield of product by electron donating/withdrawing substituents. Short reaction time, environment friendly procedure, excellent yields, inexpensive and readily available catalyst are the advantages of this procedure. All synthesized compounds were characterized by IR, 1HNMR, 13CNMR and mass spectral data.