Thiourea dioxide in water as a recyclable catalyst for the synthesis of structurally diverse dihydropyrido[2,3-d]pyrimidine-2,4-diones

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.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

Heterocycles have been found to be of much importance as several nitrogen- and oxygen-containing heterocycle compounds exist amongst the various USFDA-approved drugs. Because of the advancement of nanotechnology, nanocatalysis has found abundant applications in the synthesis of heterocyclic compounds. Numerous nanoparticles (NPs) have been utilized for several organic transformations, which led us to make dedicated efforts for the complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019. Our emphasize during the coverage of catalyzed reactions of the various MNPs such as Ag, Au, Co, Cu, Fe, Ni, Pd, Pt, Rh, Ru, Si, Ti, and Zn has not only been on nanoparticles catalyzed synthetic transformations for the synthesis of heterocyclic scaffolds, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the synthesis of desired heterocyclic scaffold.

Rust-derived Fe2O3 nanoparticles as a green catalyst for the one-pot synthesis of hydrazinyl thiazole derivatives

A novel route of one-pot multicomponent reaction of tosylates, aryl aldehydes and thiosemicarbazide for the synthesis of hydrazinyl thiazole is reported using Fe₂O₃ NPs derived from rust iron as a catalyst.

SMA/Py/ZnO as a new biocompatible polymer supported nanocatalyst for the synthesis of chromeno[2,3-d] pyrimidine-diones through a novel and efficient pathway

An efficient and simple method for the synthesis of chromeno[2,3-d]pyrimidine-diones using SMA/Py/ZnO catalyst has been reported. Zinc oxide nanoparticles were coordinated on a modified poly(styrene-comaleic anhydride) (SMA) support to prevent agglomeration and reduction catalytic activity. The polymer support was easily prepared from the reaction of 3-aminopyridine with SMA. The catalyst was characterized by using various characterization techniques such as FTIR, 1H NMR, SEM, and EDX. The catalytic activity of SMA/Py/ZnO for the synthesis of chromeno[2,3-d]pyrimidine-diones through a multicomponent reaction of 6-amino-1,3-dimethyl uracil, 3,4-methylenedioxyphenol, and an appropriate aryl aldehyde under solvent-free conditions was also studied.

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.

A One-Pot, Three-Component, Solvent-Free Synthesis of Novel 6H-Chromeno[3’,4’:5,6]Pyrido[2,3-d]Pyrimidine-Triones under Microwave Irradiation

A green and efficient method for preparing novel heterocyclic systems is established through the reaction of differently substituted benzaldehydes, barbituric acid and 4-amino-2H-chromene-2-one under solvent-free conditions. This method affords 6H-chromeno[3’,4’:5,6] pyrido[2,3-d]pyrimidine-trione derivatives in high yields and short reaction times.

Expedient multicomponent synthesis of a small library of some novel highly substituted pyrido[2,3-d]pyrimidine derivatives mediated and promoted by deep eutectic solvent and in vitro and quantum mechanical study of their antibacterial and antifungal activities

A facile and efficient catalyst- and oxidant-free multicomponent synthesis of a small library of highly substituted pyrido[2,3-d]pyrimidine derivatives is reported. The products were obtained within relatively short reaction times in good to excellent yields in the presence of deep eutectic solvents as media and promoters. Simple purification and reusability of the deep eutectic solvent were the other beneficial factors of the reported protocol. All of the synthesized derivatives were thoroughly screened for possible in vitro antibacterial and antifungal effects against twenty-two bacterial and three fungal pathogens. Some of the prepared pyrido[2,3-d]pyrimidine derivatives showed remarkable antibacterial and antifungal activities in comparison with some typical known antibacterial and antifungal agents. Finally, the derivatives possessing bioactivity effects were subjected to quantum chemical computational studies in order to reveal the probable structural and electronic effects governing the spotted bioactivities. It was found that the observed bioactivities could be best devoted to the HOMO-LUMO energy gap and para delocalization index of the corresponding derivatives.

Metal-free regioselective formation of C-N and C-O bonds with the utilization of diaryliodonium salts in water: facile synthesis of N-arylquinolones and aryloxyquinolines

Regioselective construction of crucial C-N and C-O bonds leading to N-arylquinolones and aryloxyquinolines has been accomplished by employing easily accessible diaryliodonium salts and quinolones in water under metal- and ligand-free conditions. This operationally simple strategy is significant due to mild reaction conditions, high product yields, recyclability of released iodoarenes and scalability to the gram level. The practical utility of the developed protocol was proved by the arylation of medicinally important heterocycles like acridin-9(10H)-one, 3-methylquinoxalin-2(1H)-one and 1H-benzo[d]imidazol-2(3H)-one.

An Efficient, Eco-friendly and Sustainable One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Directly from Alcohols Catalyzed by Heteropolyanion-Based Ionic Liquids

Efficient, eco-friendly and sustainable access to 3,4-dihydropyrimidin-2(1H)-ones directly from alcohols under microwave and solvent-free conditions has been reported. The practical protocol involves heteropolyanion-based catalyzed oxidation of alcohols to aldehydes with NaNO₃ as the oxidant followed by cyclocondensation with dicarbonyl compounds and urea or thiourea in a two-step, one-pot manner. Compatibility with different functional groups, good to excellent yields and reusable catalysts are the main highlights. The utilization of alcohols instead of aldehydes is a valid and green alternative to the classical Biginelli reaction.

Synthesis of the first magnetic nanoparticles with a thiourea dioxide-based sulfonic acid tag: application in the one-pot synthesis of 1,1,3-tri(1H-indol-3-yl) alkanes under mild and green conditions

Synthesis of the first thiourea dioxide-based silica-coated Fe₃O₄magnetic nanoparticles as an exquisite, extraordinary and effective catalyst for the synthesis of 1,1,3-tri(1H-indol-3-yl) alkane derivatives.

Synthesis of heterocyclic scaffolds through 6-aminouracil-involved multicomponent reactions

There is a wide range of multicomponent reactions that include 6-aminouracil in the synthesis of heterocyclic compounds. This review highlights the advances in the use of 6-aminouracil in the synthesis of various organic compounds.

[Ce(l-Pro)2]2 (Oxa) as a heterogeneous recyclable catalyst: synthesis of pyrazoles under mild reaction conditions

A highly efficient method for the synthesis of pyrazoles mediated by [Ce(l-Pro)₂]₂ (Oxa) as a heterogeneous catalyst.

First synthesis of unexpected functionalized trifluoromethylated 8-oxa-2,4-diazaspiro[5.5]undecanes via one-pot MCRs

The present study describes the first example of the synthesis of functionalized trifluoromethylated 8-oxa-2,4-diazaspiro[5.5]undecanes via one-pot MCRs.