Pyran Derivatives Research Articles

Biosynthesis of CuO nanoparticles using Acacia concinna pod and their application for the synthesis of tetra-hydrobenzo[b]pyran derivatives

Biosynthesis of CuO nanoparticles using Acacia concinna pod and their application for the synthesis of tetra-hydrobenzo[b]pyran derivatives

Three-component Synthesis of Tetrahydrobenzo[b]pyrans Using MMWCNTs-PEG-IL as a Novel Magnetic Immobilized Ionic Liquid

Introduction: A novel immobilized imidazolium type ionic liquid was synthesized using poly(ethylene glycol) (PEG) functionalized magnetic multi-walled carbon nanotubes. This immobilized ionic liquid (MMWCNTs-PEG-IL) was characterized by FT-IR, VSM, XRD, FE-SEM and EDX analysis. Method: Then, it was used as a magnetic catalyst in a three-component reaction to yield tetrahydrobenzo[b]pyran derivatives. First, optimized reaction conditions were investigated. A mixture of containing dimedone (1 mmol), malononitrile (1 mmol), benzaldehyde (1.2 mmol) and MMWCNTs-PEG-IL (0.03 g) in H2O/EtOH (5 mL) was stirred at 70 °C. After completion of the reaction, the mixture was cooled. Results: Then, an external magnet was used to separate the magnetic catalyst. This method has many advantages including high reaction yields, high TOFs, using non-toxic solvents, easy handling of catalyst, simple separation of catalyst from reaction medium and short reaction times. Conclusion: Also, the reusability of the magnetic catalyst has been investigated in 7 runs without serious loss of reaction yield.

Nickel Nanoparticles as a Sustainable Catalyst for the Synthesis of 2H‐Pyran Derivatives under Microwave Irradiation, and their Anti‐Inflammatory Activity

AbstractThis study includes an environmentally and effectively green method for the synthesis of novel 2H‐pyran derivatives 4 a–h via a one‐pot reaction of different aromatic aldehydes 1 a–h with ethyl cyanoacetate (2) and 2‐acetylphenyl‐4‐tolylsulfonate (3) in the presence of nickel oxide nanoparticles (NiO NPs) as a green catalyst in an aqueous mixed solution (EtOH: H2O, 1 : 3 ratio) using microwave irradiation. The structure of all prouducts were confirmed by spectral data and elemental analysis. All compounds were investigated for anti‐inflammatory activity compared with celecoxib as a reference drug. The obtained results indicate that 2‐[4‐(4‐tosyl oxy phenyl)‐3‐cyano‐2‐oxo‐2H‐pyran‐6‐yl]phenyl 4‐tolylsulfonate (4 b) is the most anti‐inflammatory effective, which showed after 5 h., significantly inhibited inflammation compared with the carrageenan alone group (P < 0.0001)., and when compared to the treated group with celecoxib, inflammation was inhibited 42.38 % for compound 4 b compared to celecoxib 48.39 % simultaneously. Moreover, its histopathological examination was studied and showed a significant attenuation of inflammation and edema. The results indicated that pyran derivatives could serve as promising lead compounds for further optimization as anti‐inflammatory agents.The present protocol offers several advantages, such as inexpensive, easy work, pure products, shorter reaction times, excellent yields, environmental friendliness, and easy reuse of the catalyst several times.

Reactivity Switch in Glycal Dienes toward Different Nucleophiles: Mechanistic Insight and Applications toward the Synthesis of Naphthalene-Fused Pyran Derivatives.

The stereo- and regioselective formation of chiral molecules is an interesting and important topic in organic synthesis due to its wide applicability and intricacy during synthesis. Herein, we disclose a method for the selective functionalization of glycal dienes for synthesizing different glycosides and branched sugars stereo- and regioselectively. The methodology is broad regarding the substrate scope in which various nucleophiles and glycals were explored. Furthermore, we delve into converting the synthesized products into naphthalene-fused pyran derivatives, achieved through a 4 + 2 cycloaddition followed by aromatization. Additionally, we conducted density functional theory studies to gain insight into the formation of regioselective products when different nucleophiles were employed.

On-Surface Synthesis of Macrocycles, Non-Planar Carbon Ribbons and Heteroatom-Doped Nanographenes

On-surface synthesis via covalent coupling of adsorbed molecules on metal surfaces has attracted significant attention recently due to its potential to fabricate low-dimensional carbon materials with atomic precision. The bottom-up, atomically precise synthesis of carbon nanostructures enables the tailoring of their electronic properties at a molecular level. To understand and control the surface-chemistry-driven synthesis, many efforts have been made to design innovative precursors, explore novel reaction schemes, and utilize templating effects from the substrate.My presentation focuses on high-resolution scanning probe microscopy experiments combined with density functional theory to demonstrate recent highlights on the assembly of surface-supported low-dimensional carbon structures on metal surfaces. First, the assembly and electronic structure of planar π-extended cycloparaphenylene macrocycles, representing the first nanographene with an all-armchair edge topology, will be presented [1]. The second part will discuss the bottom-up synthesis of covalently-linked non-planar carbon ribbons and their electronic properties depending on their adsorption geometry. Finally, I will conclude with the on-surface cyclomerization of oxygen heterocycles to understand the on-surface synthesis of furan and pyran derivatives from ketone-functionalized precursors on metal surfaces.[1] Xiang, et al. Nature Chem., 2022 14, 871–876.

Synthesis of Indenone-Fused Pyran Derivatives from Aryl Enaminones and Cyclopropenones through Unsymmetrical Relay C-H Bond Activation and Double C-C/C-O Bond Formation.

Presented herein is a novel synthesis of indenone-fused pyran derivatives via the cascade reactions of aryl enaminones with cyclopropenones. The formation of products involves a one-pot cascade procedure consisting of aryl C-H bond and enamine C-H bond functionalization along with C-C bond cleavage of cyclopropenone and 1,3-rearrangement of the in situ-formed allylic alcohol moiety followed by intramolecular O-nucleophilic addition and Me2NH elimination. To our knowledge, this is the first synthesis of indenone-fused pyran derivatives via simultaneous formation of both indenone and pyran scaffolds through concurrent unsymmetrical relay C-H bond activation and double C-C/C-O bond formation. Moreover, the usefulness of this method is further showcased by its suitability for large-scale synthetic scenarios and diverse transformations of products.

Lead(II) complex with methoxy-substituted beta-diketonate − structure, thermal behavior and unexpected thermolysis byproduct

New complex of lead(II) with beta-diketonate ligand PbL2 is described, where L=CH3COCHCOC(OCH3)(CH3)2, 5-methoxy-5-methylhexan-2,4-dionate). Crystal structure of the compound has been determined and its thermal properties have been studied. Chains of 1D coordination polymers form crystals of the complex, where the molecules are connected through the chelate-bridging oxygen atoms, methoxy groups remain free and form hydrogen bonds between the chains. PbL2 sublimates at 120 °C under reduced pressure (P=10−2 Torr) with partial decomposition. When heated in the condensed phase the complex decomposes with the formation of lead(II) oxide and evolution of a pyran derivative into gas phase. The mechanism of lead(II) complex thermolysis in support of the condensation of two ligands is discussed. A new organic product was identified by 13C and 1H NMR, IR and PL spectroscopy and mass spectrometry; the crystal structure of the product was determined.

Synthesis and characterisation of mixed oxides of Co–Ni catalyst and its application in microwave mediated synthesis of Benzo[b]Pyrans

We present an easy and sustainable procedure for the productive preparation of tetrahydrobenzo[b]pyran derivatives by means of many compounds condensation of dimedon, malononitrile and several aromatic aldehydes utilizing mixed bimetallic oxides of Co–Ni as a catalyst under microwave irradiation. Present protocol involves green synthesis of mixed Co–Ni oxide catalyst using milky latex of Euphorbia neriifolia. The prepared mixed Co and Ni oxide was analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier Transform Infra-Red Spectroscopy (FT-IR), Energy Dispersive X-ray Analysis (EDAX), X-ray Photoelectron Spectroscopy (XPS) & Brunauer-Emmett- Teller Analysis (BET). This green approach's significance is demonstrated by its one-pot synthesis, convenient without use of solvent shows good isolated yields. Multiple analytical techniques such as Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy are utilized to derive the structural properties. The mixed metal oxides of Co and Ni was found to be catalytically active and can be reused 12 times without significant loss of catalytic activity.

Computational Insights into Chromene/pyran Derivatives: Molecular Docking, ADMET Studies, DFT Calculations, and MD Simulations as Promising Candidates for Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative condition characterized by both motor and non-motor symptoms. Although PD is commonly associated with a decline of dopaminergic neurons in the substantia nigra, other diagnostic criteria and biomarkers also exist. In the search for novel therapeutic agents, chromene and pyran derivatives have shown potential due to their diverse pharmacological activities. This study utilizes a comprehensive computational approach to investigate the viability of chromene/pyran compounds as potential treatments for PD. The drug-likeness characteristics of these molecules were analyzed using ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) studies. Molecular docking was performed against PDB ID: 2V5Z. The best three molecules chosen were compound 7, compound 24, and compound 67 have a binding energy of -6.7, -8.6, and -10.9 kcal/mol. Molecules demonstrating positive blood-brain barrier permeability, good solubility, and favorable binding affinity were further evaluated using Density Functional Theory (DFT) calculations and Molecular Dynamics (MD) simulations to assess their electronic structure and stability. DFT calculations indicated that molecule 82 has a dipole moment of 15.70 D. RMSD and RMSF results confirmed the stability of the complexes over a 100 ns simulation, with a maximum of 3 hydrogen bonds formed.

Fluorinated Chiral Pyrans Obtained via Mechanochemical Organocatalytic Michael/oxa‐Michael Cascade

Fluorine‐containing compounds are important in medicine or crop‐protection. Herein, we show asymmetric organocatalytic Michael/oxa‐Michael cascade leading to chiral fluorinated pyrans under mechanochemical conditions. Formal oxa‐Diels‐Alder reaction between fluorine containing unsaturated keto esters and β,γ‐unsaturated ketones afforded a range of drug‐like pyran derivatives in short times and good to high yields. Ball‐milling convey the reaction in short times and high product yields, while keeping high enantiomeric purities of products. The reaction is diastereodivergent depending on the use of either monofunctional amine catalysts or bifunctional thiourea or squaramide.

Targeted potent antimicrobial and antitumor oxygen-heterocyclic-based pyran analogues: synthesis and computational studies

The process of creating a series of 3-amino-1-aryl-8-methoxy-1H-benzo[f]chromene-2-carbonitriles (4a-q) involved reacting 6-methoxynaphthalen-2-ol (1), the appropriate aromatic aldehydes (2a-q), and malononitrile (3) in an absolute ethanol/piperidine solution under Ultrasonic irradiation. However, the attempt to create 3-amino-1-aryl-1H-benzo[f]chromene-2,8-dicarbonitrile (6a, d, e) was unsuccessful when 6-cyanonaphthalen-2-ol (5) was stirred at room temperature, reflux, Microwave irradiation, or Ultrasonic irradiation. In addition, the target molecules were screened against Staphylococcus aureus (MRSA), Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Escherichia coli and Klebsiella pneumonia, as well as a panel of three human cancer cells lines such as MCF-7, HCT-116, HepG-2 and two normal cell lines HFL-1 and WI-38. The obtained results confirmed that the pyran derivatives (4 m, i, k) which have a double chlorine at 3,4/2,3/2,5-positions, a single halogen atom 3-Cl/4-Br (4c, e) and a double bromine at 3,5-positions with a single methoxy group at 2-position (4n), of phenyl ring, and, to a lesser extent, other pyran derivatives with monoihalogenated (4a, b, d, f), dihalogenated (4 g, h, j, l) or trisubstituent phenyl ring (4o, p, q). Furthermore, compounds 4b-e, g, i, j, m, and n showed negligible activity against the two normal cell lines, HFL-1 and WI-38. Moreover, compound 4 g exhibited the strongest antimicrobial activity among the other pyran derivatives (4a-f, g-q) when compared to Ciprofloxacin. The MIC was assessed and screened for compound 4 g, revealing bactericidal effects. Lastly, SAR and molecular docking were studied.

A novel heterogeneous biocatalyst based on graphene oxide for synthesis of pyran derivatives

Graphene oxide modified with tryptophan (GO-Trp) has been introduced as a new heterogeneous acid-base biocatalyst for synthesis of some pyran derivatives. GO was prepared according to the Hummer’s method and tryptophan as a low-cost green amino acid is covalently bonded to the surface of GO without any organic or toxic reagents in a green way. The new catalyst was characterized by different spectroscopic methods such as Fourier transform infrared, X-ray diffraction (XRD), etc. …. The results of XRD patterns showed an increase in the distance between the GO plates in the presence of the modifying agent which specifies the presence of amino acid between the GO layers. XPS analysis also confirmed successful modification through the presence of C–N bonds in the structure of the catalyst. In addition, improvements in thermal stability and changes in the morphology of the samples were observed using thermogravimetric analysis and Field emission scanning electron microscopy analysis respectively. Evaluation of the catalyst performance in the synthesis of some benzo[b]pyran and pyrano[3,2-c] chromene derivatives showed presentable results. Seven benzo[b]pyran (4a–4g) and five pyrano[3,2-c] chromene (4h–4l) derivatives were synthesized. GO-Trp as a safe, natural and efficient catalyst, could be reused up to 5 runs for synthesis of pyran derivatives without any significant decrease in its potency. High purity of the products and desirable yields are other points that make the present work more attractive.

Nickel oxide nanoparticles as sustainable catalysts for efficient synthesis and anti-microbial evaluation of 2-amino-4H-pyran derivatives

In the current paper, nickel oxide nanoparticles (NiO NPs) was successfully applied as a sustainable effective and recoverable catalyst for the preparation of 2-amino-4H pyran derivatives 2-11 via one-pot, three-component reaction of 4-formylphenyl-4-methyl benzenesulfonate (1) with malononitrile and active methylene compounds in green solvent water and ethanol in ratio (3:1) in excellent yield (95-98%) and shorter reaction time (5-8 min). The structures of the pyran derivatives were elucidated by elemental and spectral analyses such as IR, 1H NMR, 13C NMR and DEPT 135 spectra. Moreover, the characterization of the catalyst after and before the reaction were studied using X-ray diffraction (X-RD), scanning electron microscope (SEM), EDX techniques and IR-spectra. It has been indicated that catalyst has the same efficiency. The application of this protocol has many advantages such as eco-friendly, inexpensive, simple protocol and easy recovery of the catalyst. Overall products are designed, synthesized and studied for their anti-microbial evaluation. It has been found that is compounds 2, 3, 7 and 10 are the most active against antibacterial compression with the stander drug Ampicillin. On the other hand, Compounds 2, 3, 8, and 11 displayed the most promising antifungal activities with Amphotericin B.
 KEY WORDS: Nickel oxide nanoparticles, Pyran derivatives, X-Ray diffraction (X-RD), Antimicrobial evaluation, One-pot, Three-component reaction
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 657-670. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.9

Retraction Note to: Two Novel Pyran Derivatives: Crystal Structures, Anti-Liver Cancer Activity, and Docking Study

Retraction Note to: Two Novel Pyran Derivatives: Crystal Structures, Anti-Liver Cancer Activity, and Docking Study

Highly Regio- and Diastereoselective Synthesis of 6,7-Dihydro-4H-furo[3,4-c]pyran Derivatives through Pd-Catalyzed Formal (3 + 3) Allylic Cycloaddition of 2-Butene-1,4-diols with 2-(1-Alkynyl)-2-alken-1-ones.

A highly efficient synthesis of 7-vinyl-6,7-dihydro-4H-furo[3,4-c]pyran derivatives from 2-butene-1,4-diols and 2-(1-alkynyl)-2-alken-1-ones has been achieved with high regio- and diastereoselectivity (dr > 20:1) by Pd-catalyzed tandem heterocyclization/cross-coupling. The π-allyl palladium species Int II generated from 2-butene-1,4-diol by direct cleavage of the C-OH bond is the key to the success in this formal (3 + 3) cycloaddition reaction.

N-Heterocyclic Carbene Catalysis for Facile Access to Pentasubstituted 4H-Pyran Derivatives

AbstractThe synthesis of polysubstituted 4H-pyran derivatives has attracted considerable attention due to its wide application in agrochemicals, pharmaceuticals, and other functional molecules. We report an N-heterocyclic carbene-catalyzed [3+3] annulation reaction of β-ketone esters with enynals for rapid access to pentasubstituted 4H-pyran derivatives through a regioselective activation of the ynal. A series of 4H-pyran derivatives bearing various substituents were obtained in moderate to excellent yields. This method could find further applications in the synthesis of structurally diverse 4H-pyran-derived functional molecules from readily available starting materials.

Zn/Mo nanocomposite: An efficient and reusable catalyst for the synthesis of 4-H Pyran derivatives

A efficient, novel, inexpensive Zn/Mo nanocomposite were prepared by Sol-Gel synthesis. These nanomaterials were characterized by Powder XRD, FT-IR, FE-SEM, EDS. Under mild circumstances, the resulting nanomaterial functioned as a heterogeneous catalyst in the quick and easy production of derivatives of tetrahydrobenzo[b]pyran. The ideal circumstances for synthesising tetrahydrobenzo[b]pyrans have been assessed. The highest yield (92%) was achieved under ethanol as solvent after 7 min at 80 °C with 0.03 g of Zn/Mo NCs present. The composite oxide catalyst was found to be very efficient for the reaction. Since the nanocatalyst can be recovered and recycled four times without significantly losing catalytic activity, it has been shown to be recyclable. Exemplary yields of every synthesized derivative were obtained. A unique recyclable nanocatalyst, high product yields, and safe reaction conditions are the protocol's notable features.

The development, preparation and characterisation of novel pyran derivatives and their biological assessment

We have synthesized some novel derivatives of 4-(1-(2, 4-dinitrophenyl)-3-phenyl-1H-pyrazol-4-yl)-7,7-dimet hyl-2-(methylamino)-3nitro-6,7,8,8a-tetrahydro-4H-chromen-5(4aH)-one by the multicomponent reaction of pyrazole aldehydes derivatives, N-methyl-1-(methylthio)-2-nitroethenamine (NMSM) and 5,5-dimethylcyclohexane-1,3-dione. The synthesised compounds are confirmed by 1H NMR, IR and Mass Spectroscopy and they were then tested for antioxidant activities. In terms of antioxidant activity, compounds C-7 and C-1 were found to have the greatest and lowest levels respectively. Against Enterobacter aerogenes, compound C-5 exhibited the lowest minimum inhibitory concentration value.

Microwave‐assisted synthesis of benzo[4,5]imidazo[1,2‐a]pyrimidines and pyrano[4,3‐b]pyrans catalyzed by L‐glutamine functionalized magnetic nanoparticles in water:ethanol mixture

AbstractIn this work, we report an effective, one‐pot syntheses of benzo[4,5]imidazo[1,2‐a]pyrimidine and pyrano[4,3‐b]pyran derivatives using L‐glutamine functionalized nanoparticles (Fe3O4@SiO2@L‐glutamine NPs) under microwave irradiation. The organo‐nanocatalyst underwent characterization through diverse techniques, including FT‐IR, p‐XRD, SEM, TEM, EDX, XPS, TGA, and VSM. Microwave irradiation and multicomponent reactions synergistically yield excellent product yields (≈80%–95%) in shorter reaction times (≈6–15 min) with a broader substrate scope. The organo‐nanocatalyst displays notable catalytic efficacy, evidenced by high turnover numbers (TON) and turnover frequencies (TOF) across syntheses. This innovative protocol showcases exceptional efficiency, cost‐effectiveness, and environmental friendliness, with advantages like minimal reaction conditions, easy catalytic recovery, recyclability, operational simplicity, and the use of eco‐friendly solvents.

Correction: Nano titania-supported sulfonic acid (n-TSA) as an efficient, inexpensive, and reusable catalyst for one-pot synthesis of 1, 8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives

Correction: Nano titania-supported sulfonic acid (n-TSA) as an efficient, inexpensive, and reusable catalyst for one-pot synthesis of 1, 8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives