Showing papers on "Pyran published in 2020"

Green and Mechanochemical One-Pot Multicomponent Synthesis of Bioactive 2-amino-4H-benzo[b]pyrans via Highly Efficient Amine-Functionalized SiO2@Fe3O4 Nanoparticles.

Abstract: An ecofriendly, magnetically retrievable amine-functionalized SiO2@Fe3O4 catalyst was successfully synthesized and affirmed by several physicochemical characterization tools, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDX), and powder X-ray diffraction. Thereafter, the catalytic performance of this environmentally benign NH2@SiO2@Fe3O4 catalyst was investigated in the one-pot multicomponent synthesis of 2-amino-4H-benzo[b]pyran derivatives. The reaction was simply achieved by grinding of various substituted aromatic aldehydes, dimedone, and malononitrile at room temperature under solvent and waste-free conditions with excellent yields and high purity. Moreover, the developed catalyst not only possesses immense potential to accelerate the synthesis of bioactive pyran derivatives but also exhibits several remarkable attributes like broad functional group tolerance, durability, improved yield, reusability, and recyclability. Besides, various other fascinating advantages of this protocol are milder reaction conditions, cost effectiveness, short reaction time, and simple work up procedures.

Green protocol for synthesis of MgFe2O4 nanoparticles and study of their activity as an efficient catalyst for the synthesis of chromene and pyran derivatives under ultrasound irradiation

Abstract: In this study, the MgFe2O4 nanoparticles were synthesized via a green and simple approach. Then an effective procedure to synthesize 2-amino-7-hydroxy-4H-chromene and tetrahydrobenzo[b]pyran derivatives was established through the chemical reaction between different aldehydes, malononitrile and resorcinol (or dimedone) in the presence of MgFe2O4 nanoparticles as a beneficial catalyst in ethanol as solvent under ultrasound irradiation. Moreover, the synthesized MgFe2O4 nanoparticles were easily recovered by an external magnet and reused for four times without significant loss of their catalytic activity. Simple, fast, effective and eco-friendly as well as quick purification method along with high product yields are some of the advantages of the present chemical reaction.

Synthesis and pharmacological properties of polysubstituted 2-amino-4H-pyran-3-carbonitrile derivatives

Abstract: 2-Amino-3-cyano-4H-chromenes are structural core motifs that received increasing attention in the last years due to their interesting potential pharmacological properties. In this review, the synthetic methods for these compounds are classified based on the type of catalyst in the pertinent reactions. In addition, the wide range of pharmacological properties of these compounds is covered in a separate section.

Preparation and characterization of MNPs–PhSO 3 H as a heterogeneous catalyst for the synthesis of benzo[ b ]pyran and pyrano[3,2- c ]chromenes

Abstract: In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using tris(hydroxymethyl) aminomethane and 1,2-dichloroethane. Next, the synthesized nanocatalyst was fully characterized using FT-IR, XRD, TGA, VSM, SEM, and TEM. The results show that the synthesis of magnetic nanocatalyst has been successful with a range of 2–20 nm in size. Finally, the catalytic activity of this superparamagnetic nanocatalyst was explored for the synthesis of tetrahydrobenzo[b]pyran and 2-amino-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile derivatives. The synthesized nanocatalyst has advantages such as non-toxicity, short reaction time, easy workup, cleaner reaction profiles under mild reaction conditions.

Thieno[3,2-c]pyran: an ESIPT based fluorescence “turn-on” molecular chemosensor with AIE properties for the selective recognition of Zn2+ ion

Abstract: Excited state intramolecular proton transfer (ESIPT) based functionalized thieno[3,2-c]pyran P was designed and synthesized as a fluorescent turn-on chemosensor for the selective recognition of Zn2+ ion with a low detection limit (067 μM) Fourier transform infrared spectroscopy (FTIR), NMR, and Job plot studies were used to investigate the binding phenomenon of P and Zn2+, which was achieved via deprotonation of the hydroxyl group Zn2+ ions undergo interaction with thieno[3,2-c]pyran to afford the complex P–Zn2+, which enhances the weak emissive properties of the chemosensor P up to λem 484 nm via geometrical alteration and termination of the keto to enol oscillation In addition, thieno[3,2-c]pyran P also showed higher fluorescence in a solution of 60% water in THF owing to the aggregation-induced emission phenomenon All of these photophysical properties of chemosensor P and complex P–Zn2+ are supported by quantum chemical density functional theory (DFT) calculations The structure of P was also confirmed using single X-ray crystallography

Microwave-Assisted Three-Component Domino Synthesis of Polysubstituted 4H-Pyran Derivatives and Their Anticancer Activity

Abstract: An efficient microwave-assisted one-pot procedure has been proposed for the synthesis of new 4-aryl-6-(methylamino)-5-nitro-2-(1H-pyrrol-2-yl)-4H-pyran-3-carbonitriles by condensation of 3-oxo-3-(1H-pyrrol-2-yl)propanenitrile with (E)-N-methyl-1-(methylsulfanyl)-2-nitroethenamine and substituted benzaldehydes in the presence of a catalytic amount of piperidine using ethanol as a solvent. The transformation occurs via successive Knoevenagel condensation, Michael addition, and intramolecular cyclization. The proposed procedure is advantageous due to its one-pot mode, short reaction time, simple purification by recrystallization, and excellent yields. The product structure was confirmed using various spectroscopic techniques, including IR,1H and 13C NMR, LC/MS, elemental analysis, and single crystal X-ray diffraction study. The synthesized compounds were evaluated for their anticancer activity against 60 different human cancer cell lines in nine cancer panels, and two compounds were found to be potent against different cell lines.

A Novel Biopolymer-based Nanomagnetic Catalyst for the Synthesis of 4H-pyran and Tetrahydro-4H-chromene Derivatives

Abstract: In the present study, we have designed and synthesized a new magnetically recoverable, nanocatalyst of Ag/Fe3O4@starch. The successful synthesis and the structure of the nanocatalyst were confirmed and evaluated with several analytical techniques including XRD, EDX, VSM, FT-IR, TEM and TGA. The impact and efficiency of Ag/Fe3O4@starch were successfully investigated in the one-pot synthesis of desired 4H-pyrans and tetrahydro-4H-chromenes using three-component condensation of various aldehydes, malononitrile, and 1,3-diketoesters or cyclic 1,3-diketones. The magnetic nanocatalyst was easily recovered and reused with high catalytic activity even after up to five runs.

Anticancer activity of novel Schiff bases and azo dyes derived from 3-amino-4-hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione

Abstract: New Schiff bases and azo dyes derivatives have been synthesized via appropriate conventional methods using pyranoquinolinone as a starting material. The compounds obtained were characterized by spectral analysis and evaluated for anticancer activity in several human tumor cell lines: MCF-7 breast cancer, HepG2 liver cancer and HCT-116 colon carcinoma. 5-fluorouracil was used as a reference drug. The in vitro cytotoxicity screening results revealed that all tested compounds showed promising activity against MCF-7 cells. In particular, compounds 6a, 6b, and 7b showed excellent activity against the three human tumor cell lines. Structure-activity relationship studies indicated that the azo derivative with a trifluoromethoxy group (compound 7b) was the most potent candidate against the three human tumor cell lines (IC50, 1.82-8.06 μg/mL). Our findings highlight pyranoquinolinone analogues as a promising class of compounds for new anticancer therapies.

One-pot multi-component process for the synthesis of 4-azaphenanthrene-3,10-dione, 1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives catalyzed by the deep eutectic solvent choline chloride-oxalic acid

Abstract: An effective method based on choline chloride (ChCl)-oxalic acid (Ox) deep eutectic solvent was proposed for the synthesis of 4-azaphenanthrene-3,10-dione, 1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives. The eutectic mixture worked as both the solvent and acidic catalyst for conversion. The impacts of different variables, including the composition and volume of ChCl-Ox, and temperature, on reaction yield were studied for optimization. The crucial advantages of this process are simplicity of the experimental procedure, high yields, short reaction times, high recyclability, and the use of safe and inexpensive components.

MCM-41@Schiff base-Co(OAc)2 as an efficient catalyst for the synthesis of pyran derivatives

Abstract: Heterogeneous ordered mesoporous silica materials catalyst, MCM-41@Schiff base-Co(AcO)2, reveals high catalytic performance within the synthesis of pyran derivatives using the multicomponent reaction of aldehydes, malononitrile and 2-naphthol (or cyclohexane-1,3-dione) in water. The reactions afforded the desired products in high yields (up to 97% and 95%). The substantial feature is that the mesoporous-complex catalyst could be easily separated from the reaction mixture by centrifugation and reused at least 6 times with more than 80% yield in activity. The gram-scale experiments were achieved with good yields and implied that the catalytic method was effective and convenient for heterocyclic synthesis. What is more, the synthesized catalyst was characterized using various spectroscopic techniques to obtain the structural and functional features. The analysis results confirmed that the Co-Schiff base complex immobilized on the surface of mesoporous materials MCM-41. Finally, a plausible reaction mechanism was proposed.

Study of three-component reaction of α-ketoesters and active methylenes with OH-acids to synthesize new 2-amino-4H-pyran derivatives and evaluation of their antibacterial and antioxidant activities

Abstract: Synthesis of new derivatives of 2-amino-4H-pyrans is reported via three-component reaction of α-ketoesters, active methylenes, and OH-acids in the presence of catalytic amount of piperidine at room temperature with high to excellent yields. The structure of synthesized compounds was characterized by FTIR, 1H, 13C NMR spectroscopy, and mass spectrometry. Simplicity of procedure, mild reaction conditions, short reaction time, and easy separation of the products make this an interesting alternative to other reported approaches. Also, their antibacterial and antioxidant activities were evaluated against Staphylococcus aureus and Bacillus subtilis as Gram-positive bacteria and Escherichia coli and Pseudomonas aeruginosa as Gram-negative bacteria, as well as the radical scavenger DPPH. Among these compounds, 4l including CO2Et substituent and 6-methyl-2H-pyran-2-one moiety showed the highest antioxidant and antibacterial activities.

Adamantyl pyran-4-one derivatives and their in vitro antiproliferative activity.

Abstract: Pyran-4-one (maltol, kojic acid and chlorokojic acid 1) esters of adamantan-1-ylacetic acid were prepared through efficient synthetic routes in good yields and evaluated for their in vitro antiproliferative activity on four cancer cell lines: K562 (chronic myelogenous leukemia), HeLa (cervical cancer), Caco-2 (colorectal adenocarcinoma) and NCI-H358 (bronchioalveolar carcinoma). The results indicate that the presence and the position of the adamantyl acyl group or chlorine atom are the necessary requirement for antitumor activity of pyranone systems. Derivatives of kojic acid with either free (compounds 1 and 8) or acylated 5-OH group (compounds 2 and 9) have shown good-to-moderate activity (IC50 values ranging from 13.1 to 43.0 μM) on all cell lines. Adamantyl kojic acid derivative 5 with a free OH group on the position 2 showed activity only on the K562 cell line. It seems that removal of halogen or adamantyl unit from position 2 elicits antileukemic activity, as observed in compound 5. The positive influence of the adamantyl unit was also observed on a 3-OH acylated derivative of maltol I which was also selectively active on the same cell line. 5-O-benzylated adamantyl compounds 6 and 7 and unmodified starting pyranones were found to be inactive. Antibacterial activity of compounds was also evaluated on S. aureus ATCC 13709, M. catarrhalis ATCC 23246, E. faecalis ATCC29212 and E. coli TolC-Tn10, but no activity was observed (MIC values 128–256 µg/mL).

Introduction of a new bis-derivative of succinimide (Bis-Su) as a sustainable and efficient basic organo-catalyst for the synthesis of arylidene malononitrile and tetrahydrobenzo[ b ]pyran derivatives under green conditions

Abstract: Organo-catalysts have been under great consideration for many years because of their performance and selectivity in the reactions. In this work, a new bis-succinimide (Bis-Su) compound is prepared, identified and used as a green and efficient basic organo-catalyst for the promotion of the synthesis of arylidene malononitrile and tetrahydrobenzo[b]pyran derivatives. Using this method, both of the reactions were performed under mild conditions, during short reaction times in high yields. The catalyst can also be recycled and reused several times without a considerable decrease in its activity.