Green Reaction Conditions Research Articles

Cu@DPP-SPION: A Novel and Versatile Catalyst for the Synthesis of Thioxo-Tetrahydropyrimidine Derivatives under Mild Reaction Conditions.

The development of efficient and sustainable catalytic methodolo-gies has garnered considerable attention in contemporary organic synthesis. Herein, we present a novel approach employing the Cu@DPP-SPION catalyst for the synthesis of ethyl 4-(aryl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate derivatives. This versatile catalytic system incorporates copper nanoparticles supported on 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzoic acid-functionalized superparamagnetic iron oxide nanoparticles (SPIONs). The catalyst was meticulously characterized through scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and inductively coupled plasma (ICP) analysis. The catalytic process, exemplified by the synthesis of heterocyclic compounds, demonstrated high isolated yields, attesting to the robust performance of the catalyst. Furthermore, the reusability of the catalyst was validated through five consecutive reactions without a notable decrease in yield, while structural stability was confirmed by SEM analysis. The methodology combines green reaction conditions, room temperature operation, and facile magnetic catalyst separation, underscoring its potential for sustainable synthesis. This work highlights the promise of the Cu@DPP-SPION catalyst as an innova-tive tool in heterogeneous catalysis and its role in advancing efficient and environmentally conscious synthetic methodologies.

In situ synthesis of ultrafine Cu(ii) metal immobilized on pectin hydrogel, modified by a CoFe2O4/Pr-SO3H nanocomposite as a green catalyst for reduction of nitro compounds and synthesis of 1H-tetrazoles.

Synthesis of 5-substituted 1H-tetrazoles and reduction of a variety of nitro compounds presents a promising solution for the pharmaceutical and agricultural industries. However, the development of green catalysts with superior catalytic performance for this reaction remains a significant challenge. This research introduces a green protocol for the in situ creation of ultrafine Cu(ii) metal immobilized on the surface of pectin hydrogel (HPEC), modified by a CoFe2O4/Pr-SO3H magnetic nanocomposite, enabling the synthesis of tetrazoles and reduction of nitro compounds. This catalyst exhibits superior catalytic performance under green reaction conditions, short reaction time, catalyst separation, and thermal stability. The heterogeneous catalyst's structure and composition were thoroughly analyzed using various techniques such as FT-IR, FE-SEM, VSM, ICP-OES, TGA, XRD, BET, EDX, and X-ray mapping.

Palladium immobilized on functionalized halloysite: A robust catalyst for ligand free Suzuki–Miyaura cross coupling and synthesis of pyrano[2,3-c]pyrazole motifs via four component cascade reaction and their in-silico antitubercular screening

This research introduces a novel organically functionalized halloysite-supported palladium catalyst, HMF-EDA-TMS@HAL-Pd(II) that was synthesized and thoroughly characterized using various analytical techniques like HR-TEM, FEG-SEM, EDX, XPS, FTIR, XRD, TGA, ICP-AES, EXAFS and DFT studies. The catalyst exhibited exceptional performance in Suzuki–Miyaura cross coupling reactions, demonstrating high efficiency and reusability up to seven cycles in aqueous ethanol medium. Motivated by its promising catalytic activity, we extended our investigation to explore its applicability in the synthesis of pyrano[2,3-c]pyrazole motifs via a four-component cascade reaction affording the desired products in good to excellent yields with broad substrate scope under green reaction conditions. In-silico antitubercular screening of pyrano[2,3-c]pyrazole motifs against DprE1 enzyme have shown promising results with inhibition constants ranging between 0.030 and 0.1 μM for compounds 5b, 5k and 5 l. This protocol has the advantages of wide substrate scope, high yield, excellent functional group tolerance, high efficiency and environmental benign procedure. These findings emphasized the catalyst's versatility and potential in diverse organic transformations, highlighting its importance in advancing sustainable synthetic methodologies.

The first principles study of the dual-atom catalyst based on g-C3N5 for efficient nitrogen fixation

Electrocatalytic nitrogen reduction reaction (NRR) for ammonia production has broad prospects because of its mild green reaction conditions. However, the available catalysts cannot meet the needs of industrial ammonia production due to low catalytic activity and poor selectivity. In our work, the dual-atom catalysts (DAC) supported by g-C3N5 with transition metals dual-atom were designed based on the first principles calculation. Based on the criteria of stability, catalytic activity, and the competitive landscape between NRR and hydrogen evolution reaction (HER), the Ni2/g-C3N5 stands out as the most promising candidate among 30 designed diatomic catalysts for NRR, exhibiting remarkable potential for this reaction. In fact, the Ni2/g-C3N5 possesses low limiting potential (−0.27 V) and its selectivity of NRR is nearly 100 %. Importantly, by comprehensively considering the pivotal parameters of charge order, electronegativity, and d-band center, a dedicated descriptive descriptor has been formulated. This result not only profoundly uncovers the intrinsic origins of catalytic activity in the NRR but also significantly expedites the screening process for highly efficient catalysts. Our work not only accelerates the search for an NRR catalyst with high activity but also provides theoretical guidance for subsequent experiments on DACs.

In situ decorated pd NPs on Triazin-encapsulated Fe3O4/SiO2-NH2 as magnetic catalyst for the synthesis of diaryl ethers and oxidation of sulfides

This article is devoted to the synthesis of a new magnetic palladium catalyst that has been immobilized on A-TT-Pd coated-magnetic Fe3O4 nanoparticles. Such surface functionalization of magnetic particles is a promising method to bridge the gap between heterogeneous and homogeneous catalysis approaches. The structure, morphology, and physicochemical properties of the particles were characterized through different analytical techniques, including TEM, FT-IR, XRD, SEM, EDS, TGA-DTG, ICP, and VSM techniques. The obtained Fe3O4@SiO2@A-TT-Pd performance can show excellent catalytic activity for the synthesis of diaryl ethers and oxidation of sulfides, and the corresponding products were obtained with high yields. The advantages of this catalyst include a simple test method, green reaction conditions, no use of dangerous solvents, short reaction time, low catalyst loading, and reusability. Also, the nanocatalyst was easily separated from the reaction mixture with the help of a bar magnet and recovered and reused several times without loss of stability and activity.

Green Synthesis of Quinoline-Based Ionic Liquid.

The ever-growing menace of Antimicrobial Resistance (AMR) jeopardizes the potency of the prevailing antibiotics against the relentlessly sprouting infections spawned by bacteria, viruses, parasites as well as fungi, posing a great threat to human health and well-being. In this regard, several novel molecules have proved their mettle, with Ionic Liquids (ILs) being one of the most eco-friendly, non-volatile, and thermally stable alternatives to the existing antimicrobials, possessing high solvating potential as well as low vapor pressure. Moreover, the utilization of these entities in both stabilizing as well as destabilizing protein structures and enhancing enzymatic activity has further raised their potential in the biomedical industry. With this in view, we present the green synthesis and characterization of quinoline-based IL, owing to its immense antimicrobial potency, with low cytotoxicity and great artificial chaperone activity. Here, maneuvering the one-pot synthesis approach in solvent-free, greener reaction conditions not only ameliorated the reaction efficiency but also augmented the chemical yield. The purity of the synthesized IL was corroborated using 1H Nuclear Magnetic Resonance (NMR), 13C NMR, and Infrared (IR) spectroscopy. The biological potential of the synthesized compound is further validated by analyzing its Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) properties and authenticated using disc diffusion assay.

Synthesis of 5-substituted-1H-tetrazoles by lemon juice as a homogeneous and natural catalyst under green reaction conditions

Tetrazole, as a heterocyclic compound, exhibits a wide spectrum of applications in various industries. This research focuses on utilizing a natural catalyst in the synthesis of tetrazole derivatives. Leveraging the acidic nature of lemon juice (LJ), we employed it as a potential catalyst in the synthesis of 5-substituted-1H-tetrazole. LJ would act as the reaction medium as well. This synthesis involves the cycloaddition reaction (3 + 2) of sodium azide to benzonitrile under solvent-free conditions. Optimization of the reaction conditions including temperature, reaction time, and solvent type was tuned towards the highest yield considering the mild reaction time. The best product yield (97 %) was obtained at 90 °C, 40 min, in the absence of additional solvent. Various benzonitrile derivatives were examined at the optimized reaction condition.

Synthesis of carboxamide sensors for neurotoxic Cu2+ ions in safer green solvents and reaction conditions

Green amidation is simple and efficient for the synthesis of drugs and biomolecules. Green chemistry synthesis is always directed at achieving sustainability. Neurotoxins are critical targets for metabolic medicines to capture and eliminate from the body. Copper is a fatal brain neurotoxin. The C1-C4 probes were synthesized by reacting 3-coumarin carboxylic acid with 4-phenyl butyl amine, N-ethyl benzylamine, 4-dodecylaniline, and 3,3 - diphenyl propylamine in polar green solvent ethanol. These were tested for their metal-binding ability in environmentally safe aqueous acetonitrile with hyphenated techniques. The probes show significant binding with Cu2+ ions in the aqueous acetonitrile. The ascending order of anti-neurotoxin action is C3>C4>C2>C1 seen in the Limit of detection (Lod) values. Also, molecular mechanics (MM2) descriptors firmly point towards their use as drugs.

Continuous Flow Synthesis of Furfuryl Ethers over Pd/C Catalysts via Reductive Etherification of Furfural in Ethanol

Furfural has become one of the most promising building blocks directly derived from biomass. It can be transformed into numerous important biobased chemicals. Among them, furfuryl ethers such as furfuryl ethyl ether (FEE) and tetrahydrofurfuryl ethyl ether (THFEE) are considered to be attractive derivatives, notably as fuel components, due to their high stability and high octane numbers. Therefore, the production of furfuryl ethers from furfural via a hydrogenation route is an important academic and industrial challenge and requires the deployment of new catalytic processes under green and competitive reaction conditions. The existing processes are based on a two-step process combining hydrogenation and reaction with a strong Bronsted acid catalyst in batch conditions. For the first time, a continuous flow one-step process has been elaborated for the conversion of furfural directly into furfuryl ethers based on reductive etherification. The present work explores the catalytic performance in a continuous flow of commercial palladium catalysts supported on activated carbon for the catalytic reductive etherification of furfural with ethanol in the presence of trifluoroacetic acid. The chemical and engineering aspects, such as the mechanisms and reaction conditions, will be discussed.

Catalytic development of boron and sulphur-doped g-C3N4 supported Cu-MOF composite for nitroarenes reduction reaction

Todays, the mesoporous heteroatom-doped materials were attracted the scientist interest due to their outstanding properties such as thermal/chemical stability, high specific surface area (SSA), facile synthetic protocol and also abundance precursor. So, in this study, the advanced and applicable Boron and Sulphur-doped g-C3N4 (g-BSCN) supported Cu-MOF (Cu@g-BSCN) was prepared via in situ growth of Cu-MOF on the surface of g-BSCN using H3BO3, thiourea, Cu(NO3)2. 3H2O, and Terephthalic acid. The synergistic effect of B and S as the heteroatoms was triggered the plenty activated sites owing to the structural defect on the surface of the mesoporous g-BSCN. Moreover, the catalytic efficiency of g-BSCN was improved by in situ formation of copper-based MOF. The synthesized Cu@g-BSCN composite was utilized as the competent heterogenous catalyst in nitroarenes reduction in green and mild reaction condition (green solvent, and ambient temperature). High catalytic performance and desired recoverability are some of the benefits of this catalytic system.

Biocatalyst mediated green approach for 1,8-dioxo-octahydroxanthenes: SCXRD, Hirshfeld analysis and DFT studies as inhibitors of HIV reverse transcriptase

AIDS, caused by human immunodeficiency virus (HIV) is persistent on being one among the deadliest disease of all time. It destroys the immune system of the body and there is currently no effective cure for this. In this regard, in continuation to our studies on green catalysts, more efficient, constructive, and environmentally sustainable protocols for the synthesis of xanthene and its derivatives as HIV Reverse Transcriptase inhibitors were developed with the use of biocatalyst via baker's yeast that explores a viable approach on expanding environmental challenges and enlightens the superiority and exclusivity of this protocol. The current approach manifests numerous notable advantages that include ease of preparation, handling and benignity of the catalyst, low cost, green reaction conditions, facile workup, excellent yields (87–96 %) with extreme purity. The title compounds were docked on the crystal structure of a catalytic complex of HIV-1 reverse transcriptase (PDB: 1RTD). The C-score values achieved in the range 6.68–3.05 suggest that docking analysis was propitious signifying the review of all the forces of interaction between the ligand and the protein. The crystal studies and DFT analysis of compound 3d correlate the optimized geometrical features with empirically accessible XRD data.

Iron-Mediated Bromocyclization of Olefinic Amides for the Synthesis of Bromobenzoxazines

AbstractAn iron-mediated bromination/cyclization for the synthesis of bromobenzoxazines from olefinic amides has been successfully developed. In this protocol, the simple iron salt FeBr3 was employed as a bromination reagent, giving the bromobenzoxazine products in moderate to excellent yields. This methodology features good functional group tolerance, gram-scale synthesis, and green reaction conditions by the use of air as the terminal oxidant. Preliminary mechanistic studies suggest that a free radical pathway is involved.

MIL-88-NH2(Fe) conjugated pectin through a post-modification Ugi four-component reaction: A robust bio-based catalyst for the synthesis of cyclic carbonate via CO2 fixation reaction

The functionalization of materials via multicomponent reactions (MCRs) led to a recent surge in the interest of researchers, owing to the creation of exceptional properties in materials. Herein, a novel robust porous catalyst was prepared via the conjugation of MIL-88-NH2(Fe) and pectin (DAP/MIL-88-NH2(Fe)) through the post-modification Ugi four-component reaction (Ugi-4CR) for the first time. To achieve this aim, pectin was oxidized using sodium periodate as an oxidant agent to produce dialdehyde pectin (DAP). Next, the generated carbonyl functional groups participated in the Ugi-4CR of MIL-88-NH2(Fe), 4-methyl carboxylic acid, and cyclohexyl (c-hex) isocyanide to produce DAP/MIL-88-NH2(Fe) catalyst. The catalytic activity of the prepared bio-based catalyst was examined in producing cyclic carbonates through the chemical fixation of CO2 with epoxides in the presence of TBAB as a co-catalyst. Interestingly, catalytic experiments revealed that the prepared bio-based catalyst could be remarkably active regarding the CO2 fixation reaction and performed it in the shortest reaction time (1 h) via high CO2 adsorbent capacity. The outstanding benefits of the prepared bio-based catalyst include its non-hazardous nature, inexpensive, green and gentle reaction conditions, and ability to be reusable in several runs with slight loss of catalytic activity due to a more durable framework with high chemical and thermal stability.

Modular Access to Tetrasubstituted N−H Pyrroles by Catalytic 1,3‐Dipolar Cycloaddition of Azomethine Ylides and α,β‐Ynones

AbstractThe development of efficient synthetic strategies for the preparation of tetrasubstituted N−H pyrrole derivatives, especially in an environmentally benign fashion is important yet challenging. Herein, we report a copper(II)‐catalyzed tandem reaction involving 1,3‐dipolar cycloaddition of α,β‐ynones and glycine iminoesters, followed by copper(II)‐promoted oxidative (air) dehydrogenative aromatization, allowing de novo access to tetrasubstituted N−H pyrroles in up to 81 % yield under green reaction conditions. A possible reaction pathway is tentatively proposed. Finally, fully substituted pyrroles are available by N‐alkylation, and a preliminary phase‐transfer catalytic asymmetric N‐alkylation was also studied to give an axially chiral pyrrole.

Accessing 7,8-Dihydroquinoline-2,5-diones via Rh-Catalyzed Olefinic C-H Activation/[4+2] Cyclization.

Herein, we report a rhodium-catalyzed C-H activation/[4+2] cyclization reaction between α,β-unsaturated amides and iodonium ylides for the synthesis of novel 7,8-dihydroquinoline-2,5-diones and analogues. This protocol provides a series of pyridones fused with saturated cycles with good functional group compatibility, good water and air tolerance, and good to excellent yields under mild and green reaction conditions. Additionally, scale-up synthesis can be smoothly performed with as low as 0.25 mol % catalyst loading. Recycling experiments and different transformation experiments were also carried out to demonstrate the potential synthetic utility of this protocol.

Green and Convenient Synthesis of Pharmaceutically Active Mono and Bis-dihydroquinazolines via a One-pot Multicomponent Reaction Under Sulfamic Acid Catalysis

Introduction: Multicomponent reactions (MCRs) and green chemistry are essential criteria for the development of efficient chemical syntheses for valuable organic compounds. Method: The design, synthesis, and development of sustainable procedures for the production of novel biological and pharmaceutical molecules have gained high importance. Herein, an environmentally benign synthesis of mono- and bis-2,3-dihydroquinazolin-4(1H)-ones as pharmaceutically active compounds was carried out in good to high yields of 80-99% within 45-120 minutes. Result: The desired products were synthesized via three-component and pseudo five-component condensations of isatoic anhydride, a primary amine (aniline or ammonium acetate), and an aldehyde/dialdehyde using sulfamic acid (20%) as a solid acidic catalyst under the solvent-free condition at 100°C. Conclusion: The easy work-up procedure, metal-free and environmentally benign catalyst, green reaction conditions for performing MCRs, and high yields of pure products are some advantages of the presented protocol.

Synthesis and characterization of a Pd Schiff base complex anchored on Fe3O4 as a novel and recyclable catalyst for C[sbnd]C cross-coupling reactions

Pd Schiff base complex was immobilized onto the surface of magnetic Fe3O4 as a novel, eco‐friendly, and recyclable heterogeneous catalyst and fully characterized by BET, TEM, XRD, EDS, SEM, TGA, FT-IR, ICP‐OES, and VSM techniques. The obtained Fe3O4@SiO2@APT@BDA@Schiff base-Pd performance can show excellent catalytic activity for CC coupling reactions, and the corresponding products were obtained with high yields. The main advantages of using this catalyst include green reaction conditions, low loading of the catalyst, a simple experimental procedure, short reaction time, non‐use of hazardous organic solvents, and the ability to use various substrates. Palladium leaching was checked using ICP-OES and hot filtration. The synthesized nanocatalyst can be recovered and reused several times. The catalyst can be easily separated from the reaction mixture and recovered and reused without loss of stability and activity.

Bench-stable Nickel(II)–aryl Complex-Catalyzed cyclotrimerisation of diynes and alkynes to synthesis multisubstituted benzene derivatives

Herein, we report a (PPh3)2Ni(o-tolyl)Cl complex-catalyzed cyclotrimerisation reaction of diynes and alkynes to furnish multi-substituted benzene derivatives in moderate to excellent yields. This method features an air-stable catalyst, green reaction conditions, and excellent functional group tolerance. Additionally, this approach enables gram-scale synthesis, and the target product could also be further derivatised into important isoindolinone scaffolds. These demonstrate the potential application of this methodology.

Preparative scale Achmatowicz and aza-Achmatowicz rearrangements catalyzed by Agrocybe aegerita unspecific peroxygenase.

The unspecific peroxygenase (UPO) from Agrocybe aegerita (rAaeUPO-PaDa-I-H) is an effective and practical biocatalyst for the oxidative expansion of furfuryl alcohols/amines on a preparative scale, using the Achmatowicz and aza-Achmatowicz reaction. The high activity and stability of the enzyme, which can be produced on a large scale as an air-stable lyophilised powder, renders it a versatile and scalable biocatalyst for the preparation of synthetically valuable 6-hydroxypyranones and dihydropiperidinones. In several cases, the biotransformation out-performed the analogous chemo-catalysed process, and operates under milder and greener reaction conditions.

Photochemical alkylation of quinoxalin-2(1H)-ones with N,N,N',N'-tetraalkylethylenediamine.

A visible-light-induced C-3 alkylation of quinoxalin-2(1H)-ones with N,N,N',N'-tetraalkylethylenediamine was achieved without an external photocatalyst. The mechanism showed that quinoxalin-2(1H)-ones could act as photocatalysts. The accessibility of the reagents and the green and mild reaction conditions made this protocol an alternative method to access C-3 alkylated quinoxalin-2(1H)-ones.