Nickel Nanoparticles Catalyzed Knoevenagel Condensation of Aromatic Aldehydes with Barbituric Acids and 2-Thiobarbituric Acids

Nonoxidovanadium(IV) Complex-Catalyzed Synthesis of 2-Amino-3-cyano-4H-pyrans/4H-chromenes, Biscoumarins, and Xanthenes under Green Conditions

Reaction of [VIVO(acac)2] (Hacac = acetylacetone) with a Mannich base, N,N,N',N'-tetrakis(2-hydroxy-3,5-di-tert-butyl benzyl)-1,2-diaminoethane (H4L, I) in a 1:1 molar ratio in MeOH, leads to the formation of the nonoxidovanadium(IV) complex [VIVL] (1). Air stable complex 1 has been characterized using various spectroscopic techniques, DFT calculations, and single-crystal X-ray studies. 1 adopts distorted octahedral geometry where ligand coordinates through all coordination functionalities available. This complex has been used as a catalyst in the one-pot, three-component synthesis of 2-amino-3-cyano-4H-pyrans using 1,3-dicarbonyls (1,3-cyclohexanedione, dimedone, barbituric acid, and 4-hydroxycoumarin), malononitrile, and various substituted aromatic aldehydes in equimolar amounts employing ethanol as a green solvent. The catalytic reaction revealed that the multicomponent synthesis of 4H-pyrans and chromenes is greatly influenced by both types of 1,3-dicarbonyl compound employed and the nature of the substituent on the aromatic ring of the aldehyde. Synthesized catalyst has also been used in the synthesis of pharmacologically relevant oxygen-containing heterocycles, specifically, 1,8-dioxo-octahydro-1H-xanthenes and biscoumarins. The possible mechanism for the synthesized one-pot, multicomponent product has been proposed by isolating intermediate(s) generated during synthesis.

Microwave-assisted synthetic method of novel Bi2O3 nanostructure and its application as a high-performance nano-catalyst in preparing benzylidene barbituric acid derivatives

In this study, controllable and optimal microwave irradiation has been used to synthesize the novel nanostructures of Bi₂O₃ under environmental conditions. The final products had a thermal stability of 210°C, an average particle size distribution of 85 nm, and a surface area of 783 m²/g. The high thermodynamic stability of Bi₂O₃ nanostructures was confirmed by TG and differential scanning calorimetry (DSC) analyses. The nanostructure nature of compounds, and most importantly, the use of an effective, cost-effective, and rapid synthesis route of microwave have created significant physiochemical properties in the Bi₂O₃ products. These unexpected properties have made the possibility of potential application of these products in various fields, especially in nano-catalyst applications. It is well-documented that, as Lewis acid, bismuth nano-catalyst exhibits a great catalytic activity for the green synthesis of some bio-active barbituric acid derivatives using precursors with electron-donating or electron-withdrawing nature in high yields (80%–98%). After incorporating this catalyst into the aqueous media, all the reactions were completed within 2–3 min at room temperature. The main advantages of this method are practical facility, the availability of starting materials, and low costs besides the catalyst reusability. Additionally, the catalyst synthesis process may be carried out in the aqueous media for a short period with medium to high yields. The obtained results have opened a new window for the development of a novel nano-catalyst with practical application.

Cucurbit[6]uril supported β-Ni(OH)2 nanoparticles as a heterogeneous catalyst for the synthesis of quinazolines via acceptorless dehydrogenative coupling of alcohols with nitriles

Synthesis of a series of quinazolines using β-Ni(OH)2-CB[6] as a heterogeneous nanocatalyst.

Three Resorcin[4]arene-Based Two-Dimensional Zn(II) Supramolecular Isomers Synthesized via a Structure-Directing Strategy for Knoevenagel Condensation

Herein, in the presence of three structure-directing agents (SDAs), a family of imidazole-functionalized resorcin[4]arene-based coordination polymers (CPs), [Zn(TIC4R)(HCOO)]·HCOO·0.5DMF·1.5H₂O (1), [Zn(TIC4R)(CN)]·HCOO·DMF·2.5H₂O (2), and [Zn(TIC4R)(H₂O)]·2HCOO·2H₂O (3), were assembled under solvothermal conditions [TIC4R = tetra(imidazole) resorcin[4]arene]. 1 exhibits a double-layer structure with rectangle windows, and 2 and 3 display monolayer structures. The layers of CPs 2 and 3 are slides with different offsets along the a-axis. In addition, three CPs were used as catalysts to catalyze Knoevenagel condensations. Strikingly, all CPs exhibit remarkable catalytic performance for several substrates. To the best of our knowledge, this is the first time that a small organic acid as SDA was used in the syntheses of resorcin[4]arene-based supramolecular isomers.

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.

Complete chemical shift assignment and molecular modeling studies of two chromene derivatives as potential leads for new anticancer drugs

The compounds 7-chloro-9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthen-1-one (5) and 5-[-7-chloro-2,4-dioxo-1H, 2H, 3H, 4H, 5H-chromeno[2,3-d]pyrimidin-5-yl)]-1,3-diazinane-2,4,6-trione (7), were synthesized from dimedone and barbituric acid and had their three-dimensional structures and precise chemical shifts assignments obtained by Nuclear Magnetic Resonance (NMR) from ¹H, ¹³C, APT, COSY, HSQC, and HMBC spectra. Additional HOMO-LUMO DFT calculations corroborated the NMR results and pointed to the most stable stereoisomers of each compound. Besides, further docking and molecular dynamic studies suggest that the stereoisomers (9S)-7-chloro-9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthen-1-one, and 5-[(5S)-7-chloro-2,4-dioxo-1H, 2H, 3H, 4H, 5H-chromeno[2,3-d]pyrimidin-5-yl)]-1,3-diazinane-2,4,6-trione of these compounds may act as DNA intercalators and qualify as potential leads for the development of new anticancer drugs.Communicated by Ramaswamy H. Sarma.

Taurine as a green bio-organic catalyst for the preparation of bio-active barbituric and thiobarbituric acid derivatives in water media

Taurine, a β-amino acid that is abundantly available in the tissues of human and animals, is efficiently used as a green bio-organic catalyst in the preparation of some of the biologically active barbituric and thiobarbituric acid derivatives. In the presence of taurine, 5-Arylidene (thio) barbituric acid derivatives were prepared via Knovenagel reaction between aldehydes and (thio)barbituric acid. Using this reagent also pyrano[2,3-d]pyrimidinone(thione) derivatives were synthesized through a three-component reaction between aldehydes, (thio)barbituric and malononitrile. Both reactions are performed in water with good to excellent yields during acceptable reaction times. No organic solvent was used during reaction or separation steps and no extra-purification was exerted. Meanwhile, reusability of taurine was easy and noticeably high.

The introduction of two new imidazole-based bis-dicationic Brönsted acidic ionic liquids and comparison of their catalytic activity in the synthesis of barbituric acid derivatives

Two bis-dicationic acidic ionic liquids are prepared, used and compared in the synthesis of barbituric acid derivatives.

DABCO-based ionic liquids: green and recyclable catalysts for the synthesis of barbituric and thiobarbituric acid derivatives in aqueous media

A new and straightforward method for the synthesis of 5-arylidine barbituric and thiobarbituric acids through a reaction between barbituric acid and its thio-analogue with aldehydes using [DABCO](SO₃H)₂(HSO₄)₂) as an efficient catalyst has been reported.

One-pot synthesis of magnetic Ni@Mg(OH)2 core-shell nanocomposites as a recyclable removal agent for heavy metals

A surfactant-assisted hydrothermal route has been presented to one-pot synthesized Ni nanoparticles encapsulated in Mg(OH)2 hollow spheres. The diameter of Ni cores and the thickness of Mg(OH)2 shells are about 60-80 and 15 nm, respectively, and the size of a whole composite sphere is approximately 70-100 nm. Benefiting from the ferrimagnetic behavior of Ni cores and the high surface area of Mg(OH)2 shells, Ni@Mg(OH)2 nanocomposites exhibit excellent heavy metals adsorption capacity and recyclable property. The first removal efficiency is almost 100% for target metals, and after five cycles, the adsorption capacity remains 95%. A series of experiments show the adsorption of heavy metal ions on Ni@Mg(OH)2 follows a pseudo-second order kinetic equation and can be described by a Langmuir isotherm model.

Reaction of 6-aminouracils with aldehydes in water as both solvent and reactant under FeCl3·6H2O catalysis: towards 5-alkyl/arylidenebarbituric acids

5-Alkyl/arylidenebarbituric acids were efficiently synthesized through an FeCl₃·6H₂O catalyzed domino reaction of 6-aminouracils, water and aldehydes with water serving a dual role as both solvent and reactant, under benign conditions.

Highly Monodispersed PEG-stabilized Ni Nanoparticles: Proficient Catalyst for the Synthesis of Biologically Important Spiropyrans

A convenient and efficient synthesis of biologically and pharmacologically important spiropyrans from the condensation of malononitrile, 1,3-dicarbonyl compounds and ninhydrin/acenaphthequinone/isatin has been reported using recyclable heterogeneous polyethylene glycol (PEG)-stabilized Ni nanoparticles in ethylene glycol. This new protocol affords products in high yields and less reaction time.