Green Synthesis of 2-Amino-4H-Pyran Derivatives Using a Novel Biopolymer Nanocatalyst ND/Fe3O4/Pectin-Ag

Green Synthesis of 2-Amino-4H-Pyran Derivatives Using a Novel Biopolymer Nanocatalyst ND/Fe3O4/Pectin-Ag | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Green Synthesis of 2-Amino-4H-Pyran Derivatives Using a Novel Biopolymer Nanocatalyst ND/Fe 3 O 4 /Pectin-Ag Reza Ghalavand, Hossein Ghafuri This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6862912/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This research introduces a novel biopolymer nanocatalyst, ND/Fe 3 O 4 /Pectin-Ag, supported by nanodiamonds, for the one-pot, three-component synthesis of 2-amino-4H-pyran derivatives. The catalyst was characterized using various techniques by Fourier transforms infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FESEM), X-Ray diffraction analysis (XRD), inductively coupled plasma (ICP), Thermogravimetric analysis (TGA) and vibrating-sample magnetometer (VSM), confirming its successful synthesis and appropriate morphology. Compared to existing methods, ND/Fe 3 O 4 /Pectin-Ag offers advantages such as high efficiency (up to 98% yield), solvent-free conditions, room temperature operation, and potential reusability due to its magnetic properties. This work presents a promising green approach for the synthesis of biologically active heterocycles. Physical sciences/Chemistry Physical sciences/Chemistry/Catalysis Physical sciences/Chemistry/Green chemistry Physical sciences/Chemistry/Organic chemistry biopolymer ND/Fe3O4/Pectin-Ag 4H-pyran nanodiamond multicomponent reaction green synthesis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Nanodiamond (ND) is a carbon-based nanomaterial characterized by particle diameters of 4 − 5 nm, featuring an sp 3 -carbon diamond core and a reconstructed sp 2 -carbon surface layer [ 1 ]. Diamond nanoparticles (NDs) have emerged as a unique class of nanomaterials with broad potential applications, attributed to their remarkable properties such as biocompatibility, high surface area, and chemical inertness. The presence of sp 2 -hybridized carbon atoms on the surface of NDs provides active sites that can facilitate various chemical reactions, including catalysis [ 2 ]. One of the primary advantages of NDs as catalysts is their ability to be functionalized with diverse chemical groups, allowing for the fine-tuning of surface properties and catalytic activity. For example, modifying NDs with acidic solutions can introduce Lewis basic carbonyl groups, which can catalyze reactions like the dehydrogenation of ethylbenzene [ 3 ]. Additionally, combining NDs with other nanomaterials, such as carbon nanotubes or silicon carbide, can produce synergistic effects, further enhancing catalytic performance. The unique electronic structure of NDs also supports the incorporation of metal nanoparticles, such as palladium and platinum, which can significantly improve their catalytic efficiency [ 4 , 5 ]. The strong interaction between these metal nanoparticles and the ND support can yield highly efficient catalysts for reactions like CO oxidation and methanol oxidation [ 6 ]. Furthermore, doping NDs with heteroatoms, such as nitrogen and boron, can create surface defects that serve as active sites for catalytic reactions. In summary, NDs provide a versatile platform for developing innovative catalysts with high activity, selectivity, and stability. By precisely controlling the surface properties of NDs, it is possible to optimize their catalytic performance for various applications. Building on these examples, employing diamond nanoparticles as metal supports offers substantial potential for advancing organometallic catalysts and investigating their catalytic properties across diverse reactions. Metals commonly combined with nanodiamonds include TiO₂, Cu, Ni, Fe, Pd, and Rh, each contributing unique advantages. These metal-nanodiamond composites have shown effectiveness in various catalytic applications, such as oxidation processes, hydrogenation of carbon-carbon double and triple bonds, and hydrodechlorination reactions [ 7 – 13 ]. Polymer-based materials (PBMs), including both renewable and synthetic polymers, have become essential in fields such as the energy industry, storage batteries, supercapacitors, structural polymers, and biomedical engineering [ 14 – 16 ]. While synthetic PBMs are highly resistant to microbial degradation, this durability often results in their accumulation in the environment, leading to pollution issues. In contrast, renewable polymer-based materials offer significant environmental advantages, with greater biodegradability and sustainability [ 17 – 19 ]. Among these renewable polymers, biopolymers such as polynucleotides, polypeptides, and polysaccharides are particularly important due to their low cost, easy availability, thermal stability, non-toxicity, and effective chelating properties [ 20 , 21 ]. Polysaccharides, which are high molecular weight polymers or copolymers of carbohydrates, consist of long chains of monosaccharide units linked by glycosidic bonds. They are generally classified into two categories: homopolysaccharides (or homoglycans) and heteropolysaccharides (or heteroglycans) based on their structure [ 22 ]. Pectin, a naturally occurring polysaccharide, has garnered significant attention due to its biocompatibility, flexibility, and non-toxicity. Extracted from plant cell walls, pectin's unique structure, rich in carboxyl and hydroxyl groups, enables its application in various fields, including pharmaceuticals and biotechnology. In recent years, researchers have explored the potential of pectin as a green and sustainable platform for synthesizing metal nanoparticles. This approach offers a promising alternative to traditional methods that often involve toxic reducing agents. Pectin, a complex polysaccharide, is primarily composed of D-galacturonic acid units linked by α-(1→4) glycosidic bonds. Its structure, characterized by the presence of carboxyl and hydroxyl groups, allows for the formation of complexes with metal ions. This property has been exploited to synthesize metal nanoparticles without the need for harmful reducing agents [ 23 – 26 ]. For instance, Kadirov et al [ 27 ]. utilized pectin to create a nickel-based metal-organic framework as a non-platinum group metal catalyst for hydrogen oxidation in fuel cells. Similarly, Li and his team [ 28 ] employed pectin-derived sugars to synthesize highly stable and efficient platinum nanoparticles on 3D graphene for methanol oxidation. These examples highlight the versatility of pectin as a green and sustainable platform for nanomaterial synthesis. Multicomponent reactions (MCRs) have emerged as a powerful tool in green chemistry, offering a sustainable approach to synthesize complex molecules. By combining multiple reactants in a single pot, MCRs significantly reduce reaction steps and waste generation [ 29 ]. These reactions have been applied to the synthesis of a wide range of complex molecules, including biologically active compounds. To further enhance the efficiency and sustainability of MCRs, catalysts, particularly nanocatalysts, have been employed [ 30 ]. Magnetic nanoparticles (MNPs), such as OPSF, have gained significant attention due to their ease of separation and recyclability [ 31 ]. MCRs, coupled with the use of efficient catalysts, offer a promising avenue for the development of environmentally friendly and cost-effective synthetic strategies. The 2-amino-4H-pyran scaffold is a crucial biologically active structure in medicinal chemistry, with extensive pharmaceutical potential. These compounds exhibit a wide range of biological activities, including anticancer, anti-HIV, anti-inflammatory, antimalarial, antiviral, and antihyperglycemic effects, in addition to functioning as DNA binders, cytotoxic agents, and insecticides [ 32 – 35 ]. A straightforward approach for synthesizing 2-amino-4H-pyran derivatives involves a three-component, one-pot cyclocondensation reaction among ethyl or methyl acetoacetate, malononitrile or alkyl cyanoacetate, and various carbonyl compounds. In recent years, several modified methods have been developed using a variety of homogeneous and heterogeneous catalysts, such as Urea [ 36 ], o-phenylendiamine-functionalized SiO₂@Fe₃O₄ [ 37 ], creatine-functionalized Fe 3 O 4 @SiO 2 [ 38 ], [Cu(L′)(Imi)] [ 39 ], Fe 3 O 4 @Hal-Glu-EPI-SO 3 H IL [ 40 ], uera-chCl [ 41 ], CuFe 2 O 4 @starch [ 42 ], CoFe₂O₄-Cell/Fe(III) SSZ [ 43 ], PC/AgNPs [ 44 ], PMO-ICS [ 45 ], Fe3O4/EDTA [ 46 ], guanidinium carbonate [ 47 ], LDH@TRMS@NDBD@CuI [ 48 ]. Continuing our research group’s efforts to broaden the catalytic applications of pristine and modified Nanocomposites in multicomponent reactions (MCRs) [ 49 , 50 ], this study introduces the use of ND/Fe 3 O 4 /Pectin-Ag as a biopolymer nanocatalyst for the synthesis of 2-amino-4H-pyran derivatives. In our research, we introduce a novel heterogeneous nanocatalyst, denoted as ND/Fe 3 O 4 /Pectin-Ag, which is supported by nanodiamonds and employed in the synthesis of 2-amino-4H-pyran derivatives. Following our ongoing research into developing eco-friendly synthetic methods for organic compounds using multicomponent reactions (MCRs) and novel catalysts, we introduce a green and efficient one-pot three-component synthesis of 4H-pyrans. This synthesis involves combining an methyl/ethyl acetoacetate (2), aldehyde (3), malononitrile (4), and in the presence of ND/Fe 3 O 4 /Pectin-Ag (1) as a catalyst under mild conditions and solvent free. Notably, this is the first reported use of ND/Fe 3 O 4 /Pectin-Ag for the synthesis of this specific class of heterocycles and other reactions. Results and discussion Characterization of the prepared ND/Fe 3 O 4 /Pectin-Ag biocomposite After several steps, ND/Fe 3 O 4 /Pectin-Ag catalyst was synthesized. FT-IR spectrum of ND/Fe 3 O 4 /Pectin-Ag catalyst is shown in Fig. 1 . In the spectra FT-IR, in an absorption band of 1740 and 1630 cm − 1 , it shows the stretching vibration of the carbonyl bond (C = O). The appearance of the bands at 2850,2960 cm − 1 assigned for the asymmetric and symmetric C–H stretching vibrations Also, the strong peak that appears at 3400 cm − 1 describes the asymmetric stretching vibration of the O-H. Also, in the FT-IR spectra, the peak exhibited at 560 − 520 cm − 1 is ascribed to Fe–O–Fe stretching vibration. which is the reason for the interaction between pectin, Fe 3 O 4 and nanodiamonds. The morphology and size details of the biocomposite were investigated by SEM measurements, as shown in Fig. 2 . The SEM images of the ND/Fe 3 O 4 /Pectin-Ag nanocatalyst show that the particle shape is spherical and the particle size distribution is uniform. A histogram of the particle size distribution was constructed by counting approximately 90 particles randomly chosen from more than one FE-SEM image. The average size estimated of the ND/Fe 3 O 4 /Pectin-Ag was 35–40 nm (Fig. 3 ). The result of the EDS analysis of the ND/Fe 3 O 4 /Pectin-Ag biocomposite was illustrated in Fig. 4 . It confirms the presence of oxygen, carbon, nitrogen, iron and silver elements in the catalyst. Furthermore, the element mapping analysis clearly exhibits the well dispersion in the biocomposite (Fig. 5 ). in addition, inductively coupled plasma (ICP) analysis has used for determining the exact concentration of Silver and the obtained valued was 3.16 wt%. Thermogravimetric analysis (TGA) was performed on ND/Fe 3 O 4 /Pectin-Ag under a nitrogen atmosphere at a heating rate of 10°C/min to determine the desorption thresholds of adsorbed water and oxygen functional groups (Fig. 6 ). The thermogram reveals two primary mass loss events. The first, occurring between 100°C and 300°C, corresponds to the removal of adsorbed water and the decomposition of pectin. This aligns with the findings of Cao [ 51 ] who attributed the primary thermal event to the breakdown of sugar rings. The second mass loss, observed between 500°C and 700°C, is associated with the removal of carbon-oxygen functions from the DND surface [ 52 ]. Beyond 800°C, the minimal mass loss indicates that most carbon-oxygen functionalities have been eliminated, making this temperature suitable as the starting point for the annealing process. The magnetic properties of ND/Fe 3 O 4 /Pectin-Ag nanocatalyst were measured by vibrating-sample magnetometer (VSM) curves at room temperature. As can be seen in Fig. 7 , the hysteresis loops of the superparamagnetic behavior can be clearly observed for the prepared magnetic nanoparticles. The superparamagnetism is responsible to an applied magnetic field without retaining any magnetism after removal of the applied magnetic field. From M versus H curves, the saturation magnetization value (M s ) of uncoated MNPs was found to be 56 emu. g − 1 .[ 53 ] The saturation magnetization of this nanoparticle was 12.733 emu g − 1 . This was lower than neat Fe 3 O 4 nanoparticles. This is mainly attributed to the existence of materials on the surface of the nanoparticles. Catalytic application of ND/FeO/Pectin-Ag biocomposite in the synthesis of 2-amino-4H-pyran derivatives Initially, the reaction conducted without a catalyst or solvent at 100 ° C for 120 minutes exhibited negligible efficiency. we optimized the catalytic efficiency of different catalysts such as ND, pectin, Ag nanoparticles, Fe 3 O 4 nanoparticles (Table 1 , entry 2–5) applied for one-pot three component reaction of o- an methyl acetoacetate 2 (1 mmol), 4-Chlorobenzaldehyde 3 (1 mmol), malononitrile 4 (1 mmol) 10 mg ND/Fe 3 O 4 /Pectin-Ag catalyst in solvent-free conditions at room temperature as a model reaction (Table 1 ). After that, we studied the effects of various solvents in the reaction (entry 6–10), based on the results obtained from Table 1 , the best solvent for the highest yields in the reaction is ethanol green solvent But the reaction in solvent-free conditions also has the best yield. Finally, we studied the effects of the amount of catalyst on the reaction (11–13), and it was found that using 10 mg of ND/Fe 3 O 4 /Pectin-Ag to complete the reaction after 10 minutes in 98% yields in solvent free is sufficient as a green solvent at room temperature. Table 2, a comparison was done between the present work and others earlier reports for the synthesis of 5a . The results clearly demonstrate the superiority of the present work in saving time, energy, solvent free and high yields of the products and also the reusability of the biocomposite. Table 2. Comparison of some catalysts effects with ND/Fe 3 O 4 /Pectin-Ag biocomposite on the model reaction. Enter Ar R 1 Product Time (min) Yield (%) M.p. (°C) M.p. (°C)(Lit.) Ref 1 4-ClC 6 H 4 Me 5a 10 98 170-171 171-173 [61] 2 2-ClC 6 H 4 Me 5b 10 96 150-152 151-153 [61] 3 4-NO 2 C 6 H 4 Me 5c 15 92 154-156 155-157 [61] 4 3-NO 2 C 6 H 4 Me 5d 15 93 211-213 210-212 [61] 5 4-MeOC 6 H 4 Me 5e 25 90 140-142 141-143 [61] 6 4-MeC 6 H 4 Me 5f 25 91 164-166 165-167 [61] 7 3-HOC 6 H 4 Me 5g 25 90 138-139 136-139 [61] 8 2-NO 2 C 6 H 4 Me 5h 15 93 187-190 187-189 [61] 9 4-HOC 6 H 4 Me 5i 25 91 162-164 163-165 [61] 10 4-ClC 6 H 4 Et 5j 10 96 170-172 170-171 [62] 11 2-ClC 6 H 4 Et 5k 10 93 180-182 180-181 [62] 12 4-MeOC 6 H 4 Et 5l 15 92 142-143 142-144 [63] 13 4-MeC 6 H 4 Et 5m 15 92 175-180 177-179 [63] 14 C 6 H 5 Et 5n 20 87 176-178 175-177 [62] 15 Furfural Et 5o 25 91 173-174 172-174 [62] 16 2-Thiophene Et 5p 25 86 175-177 174-176 [62] After optimizing the reaction conditions, in order to check the scope and generality of these conditions synthesis of a various of 2-amino-4H-pyran derivatives was studied under optimal reaction conditions. Table 3 shows that all the products were obtained in excellent yield after the appropriate reaction time. Table 3 Synthesis of 2-amino-4H-pyran derivatives with ND/Fe 3 O 4 /Pectin-Ag. Entry Catalyst Catalyst amount Solvent Temp (°C) Time (min) Yield Ref. 1 CuFe 2 O 4 @starch 30 mg EtOH r.t. 25 95 54 2 Sodium alginate 20 mg EtOH Reflux 50 95 55 3 Cs-EDTA-Cell network 10 mg EtOH r.t. 10 96 56 4 CoFe 2 O 4 -Cell/Fe (III) SSZ 160 mg EtOH 60 8 98 57 5 Uera-ChCl 30 mg DES 80 120 88 58 6 KF-Al 2 O 3 16 mg EtOH r.t. 180 91 59 7 Zn(II)/Chitosan 10 mg H 2 O 60 60 96 60 8 ND/Fe 3 O 4 /Pectin-Ag 10 mg - r.t. 10 98 This work Based on the results of recent studies, A plausible mechanism has been proposed for the reaction of methyl or ethyl acetoacetate (2), aromatic aldehydes (3) and malononirile (4) in the presence of ND/Fe 3 O 4 /Pectin-Ag biocomposite (1), Initially, the oxygen atom of benzaldehyde interact via Active sites on the surface of the catalyst, Then, the occurrence of a Knoevenagel condensation through Nu attack of malononitrile carbanion to activated aldehyde along with excretion of a water molecule forms arylidene malononitrile intermediate (II). Then, this intermediate reacted as a Michael acceptor; thus, the attack of enolizable C-H activated acidic compounds to this molecule led to an open-chain intermediate (III). Finally, an intramolecular cyclization of this intermediate gave the desired products (Scheme 2 ). Recyclability of ND/FeO/Pectin-Ag The recyclability of the catalyst is one of the most important advantages and makes it useful for commercial applications. For this reason, the reusability of ND/Fe 3 O 4 /Pectin-Ag in the model reaction was investigated. In this regard, after completion of the reaction, the biocomposite were separated by an external magnet and washed with ethanol, dried and reused in subsequent reactions. It was observed that the catalyst could be reused at least 7 times without significant loss in product yields (Fig. 8 ). Conclusions In summary, we have successfully developed a novel, environmentally friendly ND/Fe3O4/Pectin-Ag nanocatalyst for the efficient synthesis of 2-amino-4H-pyran derivatives. This biopolymer-based catalyst offers numerous advantages, including high yields, rapid reaction times, and the ability to operate under mild, solvent-free conditions. Moreover, the catalyst can be easily separated from the reaction mixture using an external magnetic field, allowing for multiple reuses with minimal loss in activity. Overall, this study demonstrates a sustainable and highly effective approach for synthesizing valuable heterocyclic compounds, with potential applications in pharmaceutical and chemical industries. This method aligns well with green chemistry principles and could be further explored for broader catalytic applications. Experimental General All the solvents, chemicals and reagents were purchased from Merck, Sigma and Aldrich. The spherical detonation NDs were obtained from Plasma Chem Company (Germany). Fourier transform infrared spectroscopy (FT-IR) was recorded on a Shimadzu IR-470 spectrometer by the mrthod of KBr pellet. Melting points were measured on an Electrothermal 9100 device. 1H nuclear magnetic resonance (NMR) spectra were recorded on a Bruker DRX-500 Avance spectrometer at 500. Field Emission Scanning Electron Microscopy (FESEM) images were taken with TESCAN (MIRA) device. The magnetic properties of the nanocatalyst was carried out by Vibrating Sample Magnetometer (VSM) analysis recorded Magnetic DaneshPajoh Kashan (MDK). Elemental analysis of the nanocatalyst was carried out by energy-dispersive X-ray (EDX) analysis recorded Numerix DXP-X10P. Preparation of ND/FeO/Pectin-Ag In order to carboxylate nanodiamonds, 1 gram of diamond nanoparticles was placed in the oven at a temperature of 450 ° C for 5 hours at a rate of 1 ° C/min [ 50 ]. 500 mg of nanodiamonds were mixed in 10 ml of deionized water and then dispersed for 20 minutes. Then a mixture of acid (98% sulfuric acid and 65% nitric acid in a ratio of 1:3) was stirred at 90 ° C for 10 hours. After the reaction, the oxidized nanodiamonds were separated from the reaction by centrifugation and then several times with water. It was washed and dried in an oven at 80 ° C for 12 hours. In the next step, 500 mg of oxidized nanodiamonds was mixed in 20 ml of distilled water and dispersed for 20 minutes. then 0.7 g FeCl 3 .6H 2 O and 0.4 g FeCl 2 .4H 2 O in 80 ml of water were added to the diamond nanoparticles, and then 10 ml of ammonium hydroxide was added drop by drop under the conditions of 80°C for 40 minutes. was added to the mixture and the reaction was terminated after 3 hours. After the reaction, the nanoparticles were separated using an external magnet and washed with water and ethanol in several steps and at a temperature of 80 ° C for 24 hours. 500 mg of magnetized nanodiamond was dispersed in 100 ml of deionized water for 20 minutes, and then 100 ml of pectin solution with 100 ml of deionized water was added drop by drop to the reaction mixture and in 5 hours at 70 ° C was stirred. Finally, the reaction precipitate was removed using an external magnet, and washed with water and ethanol in several steps and at a temperature of 60 ° C for 48 hours. In the last step, 400 mg of nanocomposite was dispersed in 50 ml of deionized water for 20 minutes, then 20 ml of 0.02 M AgNO 3 was added to the mixture for 30 minutes, and then 25 ml of 0. 1 M NaBH 4 was added to the mixture for 30 minutes and then it was separated using an external magnet and washed with water and ethanol in several steps and dried at 80 ° C for 24 hours. General procedure for the synthesis of 2‑amino‑4H‑pyran 5a‑l derivatives catalyzed by ND/Fe 3 O 4 /Pectin-Ag In a 5 ml round-bottomed fask, a mixture of methyl or ethyl acetoacetate 2 (1 mmol), aromatic aldehyde 3 (1 mmol), malononitrile 4 (1 mmol) and ND/Fe 3 O 4 /Pectin-Ag 1 (10 mg) were added in a 5 ml round-bottomed fask. The obtained mixture was mechanically stirred at room temperature for appropriate time indicated in Table 2 . Afer completion of the reaction, which was confrmed by thin layer chromatography (TLC), hot EtOH (5 ml) was added After completion of the reaction, the catalyst was separated easily by an external magnet and the product was allowed at room temperature to precipitate pure product. the recycled catalyst 1 was kept in an oven at 50°C for one hour and then reused for the next runs. All the product were known compounds which were identified by characterization of their melting points (as indicated in Table 3 ) by comparison with those authentic literature samples and also in some cases their FT-IR, 1 H NMR spectral data. Spectroscopic data for 4-(4-chlorophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate ( 5a ) M.p. 170–171°C; IR (KBr, υ, cm − 1 ): 3394, 3325, 3215, 2960,2190, 1683, 1656, 1605; 1 H NMR (500 MHz, DMSO-d6): δ 2.32 (s, 3H, CH 3 ), 3.59 (s, 3H, CH 3 ), 4.19 (s, 1H, CH-), 7.06 (s, 2H, -NH 2 ), 7.15–7.17 (d, 2H, ArH), 7.32–7.34 (d, 2H, ArH). Spectroscopic data for 4-(3-nitrophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate ( 5d ) M.p. 211–213°C; IR (KBr, υ, cm − 1 ): 3450, 3309, 3191, 2962, 2189, 1670, 1650,1583; 1 H NMR (500 MHz, DMSO-d6): δ 2.26 (s, 3H, CH 3 ), 3.65 (s, 3H, CH 3 ), 4.41 (s, 1H, CH-), 7.18 (s, 2H, -NH 2 ), 7.60 (m, 1H, ArH), 7.65–7.66 (d, 1H, ArH), 7.97 (s, 1H, ArH), 8.05–8.07 (d, 1H, ArH). Declarations Acknowledgements The authors gratefully acknowledge the partial support from the Research Council of the Iran University of Science and Technology. Supporting Information Additional supporting information including spectroscopic characterization data of the nanocatalyst and the products such as FT-IR and 1 H NMR can be found in the online version of this article at the publisher’s web site. Data availability All data that support the findings of this study are included within the article and supplementary files. References Mochalin, V., Shenderova, O., Ho, D. and Gogotsi, Y. 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A novel and eco-friendly o-phenylendiamine stabilized on silica-coated magnetic nanocatalyst for the synthesis of indenoquinoline derivatives under ultrasonic-assisted solvent-free conditions. Iran. J. Catal . 8 , 221 (2018). Ghalavand, R., Ghafuri, H. and Ardeshiri, H.H. Preparation of nanodiamond anchored on copper tannic acid as a heterogenous catalyst for synthesis of 1, 4-benzodiazepines derivatives. Scientific Reports . 14 , 8655 (2024). Liu, Y. et al. Synthesis, characterization, and application of microbe-triggered controlled-release kasugamycin–pectin conjugate. Journal of agricultural and food chemistry . 63 , 4263-4268 (2015). Banisaid, M. and Kharat, A.N. Synthesis and Characterizations of Nanodiamond and Its Application as Anti-Polishing Agent on SiO 2 Substrate. Int. J. Chem. Sci . 16 , 262 (2018). Maleki, A., Zand, P. and Mohseni, Z. Fe 3 O 4 @ PEG-SO 3 H rod-like morphology along with the spherical nanoparticles: novel green nanocomposite design, preparation, characterization and catalytic application. RSC Advances . 6 , 110928-110934, (2016). Kamalzare, M., Bayat, M. and Maleki, A. Green and efficient three-component synthesis of 4H-pyran catalysed by CuFe 2 O 4 @ starch as a magnetically recyclable bionanocatalyst. Royal Society Open Science . 7 , 200385, (2020). Dekamin, M.G. et al. Sodium alginate: An efficient biopolymeric catalyst for green synthesis of 2-amino-4H-pyran derivatives. International journal of biological macromolecules . 87 ,172-179, (2016). Rostami, N., Dekamin, M.G., Valiey, E. and Fanimoghadam, H. Chitosan-EDTA-Cellulose network as a green, recyclable and multifunctional biopolymeric organocatalyst for the one-pot synthesis of 2-amino-4H-pyran derivatives. Scientific Reports . 12 , 8642 (2022). Rostamizadeh, S., Daneshfar, Z. and Khazaei, A. Ferric sulfasalazine sulfa drug complex supported on cobalt ferrite cellulose; evaluation of its activity in MCRs. Catalysis Letters . 150 , 2091-2114 (2020). Hakiminasab, S. et al. Efficient pyran derivatives synthesis in DES medium and their antimicrobial evaluation as inhibitors of mycobacterium bovis (BCG). Journal of the Iranian Chemical Society , 18 . 2575-2582 (2021). Kharbangar, I., Rohman, M.R., Mecadon, H. and Myrboh, B. KF-Al 2 O 3 as an Efficient and Recyclable Basic Catalyst for the Synthesis of 4H-Pyran-3-carboxylates and 5-Acetyl-4H-pyrans. Int. J. Org. Chem . 2 , 282, (2012). Taoufyk, A. et al. Immobilization of Zn (II) on Chitosan from Callinectes Sapidus Shells as an Efficient Heterogeneous Catalyst for the Synthesis of 4H-Pyran Derivatives. Journal of Inorganic and Organometallic Polymers and Materials . 1-15, (2024). Ghassemi, M. and Maleki, A. Clean one-pot multicomponent synthesis of pyrans using a green and magnetically recyclable heterogeneous nanocatalyst. SynOpen . 5 , 100-103 (2021). Rostami, N., Dekamin, M.G., Valiey, E. and Fanimoghadam, H. Chitosan-EDTA-Cellulose network as a green, recyclable and multifunctional biopolymeric organocatalyst for the one-pot synthesis of 2-amino-4 H-pyran derivatives. Scientific Reports . 12 , 8642, (2022). Khurana, J.M. and Chaudhary, A. Efficient and Green Synthesis of 4H-pyrans and 4H-pyrano [2, 3-c] Pyrazoles Catalyzed by Task-specific Ionic Liquid [bmim] OH under Solvent-free Conditions. Green Chemistry Letters and Reviews . 5 , 633-638 (2012). Table 1 Table 1 is available in the Supplementary Files section. Schemes Schemes are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files SupportingInformation.doc Table1.docx floatimage1.png Scheme 1. Preparation of ND/Fe 3 O 4 /Pectin-Ag and synthesis of 2-amino-4H-pyran derivatives in the presence of ND/Fe 3 O 4 /Pectin-Ag. floatimage10.png Scheme 2. The possible reaction mechanism for the synthesis of 2-amino-4H-pyran derivation catalyzed by ND/Fe 3 O 4 /Pectin-Ag. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6862912","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":472076195,"identity":"7df673b2-5f95-4ed3-a884-81b56ac73953","order_by":0,"name":"Reza Ghalavand","email":"","orcid":"","institution":"Iran University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Reza","middleName":"","lastName":"Ghalavand","suffix":""},{"id":472076196,"identity":"31b4ca20-d6d9-4d99-8777-c7bf5bf23bd0","order_by":1,"name":"Hossein Ghafuri","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1UlEQVRIiWNgGAWjYDACCQaGD0BSjg0mwIZPNVQL4wwgaQxUydhAihaGxAaYFoJAPrr5YTPvHov0Pon05w8YauwY+KQP4NdieOeYYTPPM4ncNokcwwaGY8kMbHwJBLTMSDB/zHMArAXoMLYDDGw8BBxmOCP9YzNQSzqbRPrDBoZ/RGiRB7oHpCWBTSLBsIGxjQgtBhI5hY1zDkgYtvG8MZyR2JfMQ9iWGekbG94cqJOXb09/8OHDNzs5+R5CthxA5iUwMBCyA2hLA0Elo2AUjIJRMOIBAKyzOpsOJPYcAAAAAElFTkSuQmCC","orcid":"","institution":"Iran University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Hossein","middleName":"","lastName":"Ghafuri","suffix":""}],"badges":[],"createdAt":"2025-06-10 12:08:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6862912/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6862912/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84922526,"identity":"4c077378-ce75-4868-bdeb-d3e9a30ba3c8","added_by":"auto","created_at":"2025-06-18 20:21:45","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":123839,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectrum of Pectin (a), ND-CO\u003csub\u003e2\u003c/sub\u003eH (b) and ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/5dac884929c6fcaf393f7650.png"},{"id":84922525,"identity":"84a8b4a0-b1ce-4639-acc1-2cb32d636d81","added_by":"auto","created_at":"2025-06-18 20:21:45","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":72752,"visible":true,"origin":"","legend":"\u003cp\u003eSEM image of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/eb5b2d69b101e6c2c5ede676.png"},{"id":84922527,"identity":"f9aab0ec-8db9-4a46-86ec-628d6a4a0380","added_by":"auto","created_at":"2025-06-18 20:21:45","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":84112,"visible":true,"origin":"","legend":"\u003cp\u003enanoparticle size distribution of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag analyzed by FE-SEM imaging.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/e3308fabd30a910221e6efa9.png"},{"id":84922536,"identity":"56213274-80d8-41a6-99b7-e076fb50cc0e","added_by":"auto","created_at":"2025-06-18 20:21:46","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":87959,"visible":true,"origin":"","legend":"\u003cp\u003eEDS analysis of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/32e3fce440d30065ff9b8f5a.png"},{"id":84922973,"identity":"817fe238-3ae7-4906-9c1e-ed359f250bba","added_by":"auto","created_at":"2025-06-18 20:37:46","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":448762,"visible":true,"origin":"","legend":"\u003cp\u003eelemental mapping images of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/0a32c9c858a52f9918ab27f2.png"},{"id":84922530,"identity":"4628b549-3db1-4fdd-be2d-653f07d17def","added_by":"auto","created_at":"2025-06-18 20:21:45","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":74481,"visible":true,"origin":"","legend":"\u003cp\u003eTGA spectra of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite under N\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/8a831dd3a5067317cdd58921.png"},{"id":84922538,"identity":"41880233-4331-47d5-b857-d0c62c67df8f","added_by":"auto","created_at":"2025-06-18 20:21:46","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":31970,"visible":true,"origin":"","legend":"\u003cp\u003eVSM magnetization curve of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/53f61854510e73d8d9f69d47.png"},{"id":84922877,"identity":"8374f5f6-fcf6-41ad-802c-81d44cf3dd66","added_by":"auto","created_at":"2025-06-18 20:29:46","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":51782,"visible":true,"origin":"","legend":"\u003cp\u003eReusability diagram of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/7612abf6836c5c5c4af1b680.png"},{"id":101673721,"identity":"f033a5ab-b79b-472d-b554-4803f271f37e","added_by":"auto","created_at":"2026-02-02 13:13:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1920073,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/63f399ae-0d4b-4e20-9a6b-1eba4148a22f.pdf"},{"id":84922533,"identity":"beea3494-7bf6-448e-9c31-5d2f690bd838","added_by":"auto","created_at":"2025-06-18 20:21:46","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1160704,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.doc","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/dd8b542a2d13b9765e7d9908.doc"},{"id":84922528,"identity":"9287e2bc-ab57-4ad8-9e59-2f321f045439","added_by":"auto","created_at":"2025-06-18 20:21:45","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":34761,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/3adbb0e21dd338bd6fc9a3dc.docx"},{"id":84922534,"identity":"96e2b8b9-eada-4226-825c-64a3acdba010","added_by":"auto","created_at":"2025-06-18 20:21:46","extension":"png","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":77642,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1.\u003c/strong\u003e Preparation of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag and synthesis of 2-amino-4H-pyran derivatives in the presence of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/f8d632b6980bbc308598c56b.png"},{"id":84922871,"identity":"de138c81-947c-4488-9979-5dba11409067","added_by":"auto","created_at":"2025-06-18 20:29:45","extension":"png","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":74455,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 2. \u003c/strong\u003eThe possible reaction mechanism for the synthesis of 2-amino-4H-pyran derivation catalyzed by ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag.\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-6862912/v1/b94fff5f6d60e0c547f2c3be.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eGreen Synthesis of 2-Amino-4H-Pyran Derivatives Using a Novel Biopolymer Nanocatalyst ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eNanodiamond (ND) is a carbon-based nanomaterial characterized by particle diameters of 4\u0026thinsp;\u0026minus;\u0026thinsp;5 nm, featuring an sp\u003csup\u003e3\u003c/sup\u003e-carbon diamond core and a reconstructed sp\u003csup\u003e2\u003c/sup\u003e-carbon surface layer [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Diamond nanoparticles (NDs) have emerged as a unique class of nanomaterials with broad potential applications, attributed to their remarkable properties such as biocompatibility, high surface area, and chemical inertness. The presence of sp\u003csup\u003e2\u003c/sup\u003e-hybridized carbon atoms on the surface of NDs provides active sites that can facilitate various chemical reactions, including catalysis [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. One of the primary advantages of NDs as catalysts is their ability to be functionalized with diverse chemical groups, allowing for the fine-tuning of surface properties and catalytic activity. For example, modifying NDs with acidic solutions can introduce Lewis basic carbonyl groups, which can catalyze reactions like the dehydrogenation of ethylbenzene [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAdditionally, combining NDs with other nanomaterials, such as carbon nanotubes or silicon carbide, can produce synergistic effects, further enhancing catalytic performance. The unique electronic structure of NDs also supports the incorporation of metal nanoparticles, such as palladium and platinum, which can significantly improve their catalytic efficiency [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The strong interaction between these metal nanoparticles and the ND support can yield highly efficient catalysts for reactions like CO oxidation and methanol oxidation [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Furthermore, doping NDs with heteroatoms, such as nitrogen and boron, can create surface defects that serve as active sites for catalytic reactions. In summary, NDs provide a versatile platform for developing innovative catalysts with high activity, selectivity, and stability. By precisely controlling the surface properties of NDs, it is possible to optimize their catalytic performance for various applications. Building on these examples, employing diamond nanoparticles as metal supports offers substantial potential for advancing organometallic catalysts and investigating their catalytic properties across diverse reactions. Metals commonly combined with nanodiamonds include TiO₂, Cu, Ni, Fe, Pd, and Rh, each contributing unique advantages. These metal-nanodiamond composites have shown effectiveness in various catalytic applications, such as oxidation processes, hydrogenation of carbon-carbon double and triple bonds, and hydrodechlorination reactions [\u003cspan additionalcitationids=\"CR8 CR9 CR10 CR11 CR12\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePolymer-based materials (PBMs), including both renewable and synthetic polymers, have become essential in fields such as the energy industry, storage batteries, supercapacitors, structural polymers, and biomedical engineering [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. While synthetic PBMs are highly resistant to microbial degradation, this durability often results in their accumulation in the environment, leading to pollution issues. In contrast, renewable polymer-based materials offer significant environmental advantages, with greater biodegradability and sustainability [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Among these renewable polymers, biopolymers such as polynucleotides, polypeptides, and polysaccharides are particularly important due to their low cost, easy availability, thermal stability, non-toxicity, and effective chelating properties [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Polysaccharides, which are high molecular weight polymers or copolymers of carbohydrates, consist of long chains of monosaccharide units linked by glycosidic bonds. They are generally classified into two categories: homopolysaccharides (or homoglycans) and heteropolysaccharides (or heteroglycans) based on their structure [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Pectin, a naturally occurring polysaccharide, has garnered significant attention due to its biocompatibility, flexibility, and non-toxicity. Extracted from plant cell walls, pectin's unique structure, rich in carboxyl and hydroxyl groups, enables its application in various fields, including pharmaceuticals and biotechnology. In recent years, researchers have explored the potential of pectin as a green and sustainable platform for synthesizing metal nanoparticles. This approach offers a promising alternative to traditional methods that often involve toxic reducing agents. Pectin, a complex polysaccharide, is primarily composed of D-galacturonic acid units linked by α-(1\u0026rarr;4) glycosidic bonds. Its structure, characterized by the presence of carboxyl and hydroxyl groups, allows for the formation of complexes with metal ions. This property has been exploited to synthesize metal nanoparticles without the need for harmful reducing agents [\u003cspan additionalcitationids=\"CR24 CR25\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. For instance, Kadirov et al [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. utilized pectin to create a nickel-based metal-organic framework as a non-platinum group metal catalyst for hydrogen oxidation in fuel cells. Similarly, Li and his team [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] employed pectin-derived sugars to synthesize highly stable and efficient platinum nanoparticles on 3D graphene for methanol oxidation. These examples highlight the versatility of pectin as a green and sustainable platform for nanomaterial synthesis.\u003c/p\u003e \u003cp\u003eMulticomponent reactions (MCRs) have emerged as a powerful tool in green chemistry, offering a sustainable approach to synthesize complex molecules. By combining multiple reactants in a single pot, MCRs significantly reduce reaction steps and waste generation [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. These reactions have been applied to the synthesis of a wide range of complex molecules, including biologically active compounds. To further enhance the efficiency and sustainability of MCRs, catalysts, particularly nanocatalysts, have been employed [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Magnetic nanoparticles (MNPs), such as OPSF, have gained significant attention due to their ease of separation and recyclability [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. MCRs, coupled with the use of efficient catalysts, offer a promising avenue for the development of environmentally friendly and cost-effective synthetic strategies.\u003c/p\u003e \u003cp\u003eThe 2-amino-4H-pyran scaffold is a crucial biologically active structure in medicinal chemistry, with extensive pharmaceutical potential. These compounds exhibit a wide range of biological activities, including anticancer, anti-HIV, anti-inflammatory, antimalarial, antiviral, and antihyperglycemic effects, in addition to functioning as DNA binders, cytotoxic agents, and insecticides [\u003cspan additionalcitationids=\"CR33 CR34\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA straightforward approach for synthesizing 2-amino-4H-pyran derivatives involves a three-component, one-pot cyclocondensation reaction among ethyl or methyl acetoacetate, malononitrile or alkyl cyanoacetate, and various carbonyl compounds. In recent years, several modified methods have been developed using a variety of homogeneous and heterogeneous catalysts, such as Urea [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], o-phenylendiamine-functionalized SiO₂@Fe₃O₄ [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e], creatine-functionalized Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@SiO\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e], [Cu(L\u0026prime;)(Imi)] [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e], Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@Hal-Glu-EPI-SO\u003csub\u003e3\u003c/sub\u003eH IL [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e], uera-chCl [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], CuFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@starch [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e], CoFe₂O₄-Cell/Fe(III) SSZ [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], PC/AgNPs [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e], PMO-ICS [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e], Fe3O4/EDTA [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e], guanidinium carbonate [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e], LDH@TRMS@NDBD@CuI [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Continuing our research group\u0026rsquo;s efforts to broaden the catalytic applications of pristine and modified Nanocomposites in multicomponent reactions (MCRs) [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e], this study introduces the use of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag as a biopolymer nanocatalyst for the synthesis of 2-amino-4H-pyran derivatives.\u003c/p\u003e \u003cp\u003eIn our research, we introduce a novel heterogeneous nanocatalyst, denoted as ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag, which is supported by nanodiamonds and employed in the synthesis of 2-amino-4H-pyran derivatives. Following our ongoing research into developing eco-friendly synthetic methods for organic compounds using multicomponent reactions (MCRs) and novel catalysts, we introduce a green and efficient one-pot three-component synthesis of 4H-pyrans. This synthesis involves combining an methyl/ethyl acetoacetate (2), aldehyde (3), malononitrile (4), and in the presence of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag (1) as a catalyst under mild conditions and solvent free. Notably, this is the first reported use of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag for the synthesis of this specific class of heterocycles and other reactions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization of the prepared ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite\u003c/h2\u003e \u003cp\u003eAfter several steps, ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag catalyst was synthesized. FT-IR spectrum of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag catalyst is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. In the spectra FT-IR, in an absorption band of 1740 and 1630 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, it shows the stretching vibration of the carbonyl bond (C\u0026thinsp;=\u0026thinsp;O). The appearance of the bands at 2850,2960 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e assigned for the asymmetric and symmetric C\u0026ndash;H stretching vibrations Also, the strong peak that appears at 3400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e describes the asymmetric stretching vibration of the O-H. Also, in the FT-IR spectra, the peak exhibited at 560\u0026thinsp;\u0026minus;\u0026thinsp;520 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is ascribed to Fe\u0026ndash;O\u0026ndash;Fe stretching vibration. which is the reason for the interaction between pectin, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and nanodiamonds.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe morphology and size details of the biocomposite were investigated by SEM measurements, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The SEM images of the ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag nanocatalyst show that the particle shape is spherical and the particle size distribution is uniform. A histogram of the particle size distribution was constructed by counting approximately 90 particles randomly chosen from more than one FE-SEM image. The average size estimated of the ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag was 35\u0026ndash;40 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe result of the EDS analysis of the ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite was illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. It confirms the presence of oxygen, carbon, nitrogen, iron and silver elements in the catalyst. Furthermore, the element mapping analysis clearly exhibits the well dispersion in the biocomposite (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). in addition, inductively coupled plasma (ICP) analysis has used for determining the exact concentration of Silver and the obtained valued was 3.16 wt%.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThermogravimetric analysis (TGA) was performed on ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag under a nitrogen atmosphere at a heating rate of 10\u0026deg;C/min to determine the desorption thresholds of adsorbed water and oxygen functional groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The thermogram reveals two primary mass loss events. The first, occurring between 100\u0026deg;C and 300\u0026deg;C, corresponds to the removal of adsorbed water and the decomposition of pectin. This aligns with the findings of Cao [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e] who attributed the primary thermal event to the breakdown of sugar rings. The second mass loss, observed between 500\u0026deg;C and 700\u0026deg;C, is associated with the removal of carbon-oxygen functions from the DND surface [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. Beyond 800\u0026deg;C, the minimal mass loss indicates that most carbon-oxygen functionalities have been eliminated, making this temperature suitable as the starting point for the annealing process.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe magnetic properties of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag nanocatalyst were measured by vibrating-sample magnetometer (VSM) curves at room temperature. As can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, the hysteresis loops of the superparamagnetic behavior can be clearly observed for the prepared magnetic nanoparticles. The superparamagnetism is responsible to an applied magnetic field without retaining any magnetism after removal of the applied magnetic field. From M versus H curves, the saturation magnetization value (M\u003csub\u003es\u003c/sub\u003e) of uncoated MNPs was found to be 56 emu. g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.[\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e] The saturation magnetization of this nanoparticle was 12.733 emu g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. This was lower than neat Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles. This is mainly attributed to the existence of materials on the surface of the nanoparticles.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCatalytic application of ND/FeO/Pectin-Ag biocomposite in the synthesis of 2-amino-4H-pyran derivatives\u003c/h3\u003e\n\u003cp\u003eInitially, the reaction conducted without a catalyst or solvent at 100\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 120 minutes exhibited negligible efficiency. we optimized the catalytic efficiency of different catalysts such as ND, pectin, Ag nanoparticles, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, entry 2\u0026ndash;5) applied for one-pot three component reaction of o- an methyl acetoacetate \u003cstrong\u003e2\u003c/strong\u003e (1 mmol), 4-Chlorobenzaldehyde \u003cstrong\u003e3\u003c/strong\u003e (1 mmol), malononitrile \u003cstrong\u003e4\u003c/strong\u003e (1 mmol) 10 mg ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag catalyst in solvent-free conditions at room temperature as a model reaction (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). After that, we studied the effects of various solvents in the reaction (entry 6\u0026ndash;10), based on the results obtained from Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, the best solvent for the highest yields in the reaction is ethanol green solvent But the reaction in solvent-free conditions also has the best yield. Finally, we studied the effects of the amount of catalyst on the reaction (11\u0026ndash;13), and it was found that using 10 mg of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag to complete the reaction after 10 minutes in 98% yields in solvent free is sufficient as a green solvent at room temperature.\u003c/p\u003e\n\u003cp\u003eTable 2, a comparison was done between the present work and others earlier reports for the synthesis of\u0026nbsp;\u003cstrong\u003e5a\u003c/strong\u003e. The results clearly demonstrate the superiority of the present work in saving time, energy, solvent free and high yields of the products and also the reusability of the biocomposite.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eTable 2.\u0026nbsp;\u003c/strong\u003eComparison of some catalysts effects with ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite on the model reaction.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"left\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003eEnter\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003eAr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eR\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003eProduct\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003eTime (min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003eYield (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003eM.p. (\u0026deg;C)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 16%;\"\u003e\n \u003cp\u003eM.p. (\u0026deg;C)(Lit.)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003eRef\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-ClC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e170-171\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e171-173\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e2-ClC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e150-152\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e151-153\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-NO\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e154-156\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e155-157\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e3-NO\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e211-213\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e210-212\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-MeOC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e140-142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e141-143\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-MeC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5f\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e164-166\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e165-167\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e3-HOC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5g\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e138-139\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e136-139\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e2-NO\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e187-190\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e187-189\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-HOC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eMe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5i\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e162-164\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e163-165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[61]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-ClC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5j\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e170-172\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e170-171\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[62]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e2-ClC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5k\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e180-182\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e180-181\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[62]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-MeOC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5l\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e142-143\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e142-144\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[63]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e4-MeC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5m\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e175-180\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e177-179\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[63]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003eC\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e176-178\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e175-177\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[62]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003eFurfural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5o\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e173-174\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e172-174\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[62]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 16.1667%;\"\u003e\n \u003cp\u003e2-Thiophene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 6%;\"\u003e\n \u003cp\u003eEt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11%;\"\u003e\n \u003cp\u003e5p\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 9%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10%;\"\u003e\n \u003cp\u003e86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8333%;\"\u003e\n \u003cp\u003e175-177\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14%;\"\u003e\n \u003cp\u003e174-176\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 13%;\"\u003e\n \u003cp\u003e[62]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\u0026nbsp;After optimizing the reaction conditions, in order to check the scope and generality of these conditions synthesis of a various of 2-amino-4H-pyran derivatives was studied under optimal reaction conditions. Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows that all the products were obtained in excellent yield after the appropriate reaction time.\u0026nbsp;\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eSynthesis of 2-amino-4H-pyran derivatives with ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eEntry\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCatalyst\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCatalyst amount\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSolvent\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTemp (\u0026deg;C)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTime (min)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eYield\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRef.\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"1\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCuFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@starch\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEtOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003er.t.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSodium alginate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEtOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eReflux\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e55\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCs-EDTA-Cell network\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEtOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003er.t.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-Cell/Fe (III) SSZ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e160 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEtOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUera-ChCl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDES\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eKF-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEtOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003er.t.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e180\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eZn(II)/Chitosan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10 mg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003er.t.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eThis work\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eBased on the results of recent studies, A plausible mechanism has been proposed for the reaction of methyl or ethyl acetoacetate (2), aromatic aldehydes (3) and malononirile (4) in the presence of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag biocomposite (1), Initially, the oxygen atom of benzaldehyde interact via Active sites on the surface of the catalyst, Then, the occurrence of a Knoevenagel condensation through Nu attack of malononitrile carbanion to activated aldehyde along with excretion of a water molecule forms arylidene malononitrile intermediate (II). Then, this intermediate reacted as a Michael acceptor; thus, the attack of enolizable C-H activated acidic compounds to this molecule led to an open-chain intermediate (III). Finally, an intramolecular cyclization of this intermediate gave the desired products (Scheme \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eRecyclability of ND/FeO/Pectin-Ag\u003c/h3\u003e\n\u003cp\u003eThe recyclability of the catalyst is one of the most important advantages and makes it useful for commercial applications. For this reason, the reusability of ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag in the model reaction was investigated. In this regard, after completion of the reaction, the biocomposite were separated by an external magnet and washed with ethanol, dried and reused in subsequent reactions. It was observed that the catalyst could be reused at least 7 times without significant loss in product yields (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, we have successfully developed a novel, environmentally friendly ND/Fe3O4/Pectin-Ag nanocatalyst for the efficient synthesis of 2-amino-4H-pyran derivatives. This biopolymer-based catalyst offers numerous advantages, including high yields, rapid reaction times, and the ability to operate under mild, solvent-free conditions. Moreover, the catalyst can be easily separated from the reaction mixture using an external magnetic field, allowing for multiple reuses with minimal loss in activity. Overall, this study demonstrates a sustainable and highly effective approach for synthesizing valuable heterocyclic compounds, with potential applications in pharmaceutical and chemical industries. This method aligns well with green chemistry principles and could be further explored for broader catalytic applications.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eGeneral\u003c/h2\u003e\n \u003cp\u003eAll the solvents, chemicals and reagents were purchased from Merck, Sigma and Aldrich. The spherical detonation NDs were obtained from Plasma Chem Company (Germany). Fourier transform infrared spectroscopy (FT-IR) was recorded on a Shimadzu IR-470 spectrometer by the mrthod of KBr pellet. Melting points were measured on an Electrothermal 9100 device. 1H nuclear magnetic resonance (NMR) spectra were recorded on a Bruker DRX-500 Avance spectrometer at 500. Field Emission Scanning Electron Microscopy (FESEM) images were taken with TESCAN (MIRA) device. The magnetic properties of the nanocatalyst was carried out by Vibrating Sample Magnetometer (VSM) analysis recorded Magnetic DaneshPajoh Kashan (MDK). Elemental analysis of the nanocatalyst was carried out by energy-dispersive X-ray (EDX) analysis recorded Numerix DXP-X10P.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003ePreparation of ND/FeO/Pectin-Ag\u003c/h3\u003e\n\u003cp\u003eIn order to carboxylate nanodiamonds, 1 gram of diamond nanoparticles was placed in the oven at a temperature of 450\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 5 hours at a rate of 1\u003csup\u003e\u0026deg;\u003c/sup\u003eC/min [\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e]. 500 mg of nanodiamonds were mixed in 10 ml of deionized water and then dispersed for 20 minutes. Then a mixture of acid (98% sulfuric acid and 65% nitric acid in a ratio of 1:3) was stirred at 90\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 10 hours. After the reaction, the oxidized nanodiamonds were separated from the reaction by centrifugation and then several times with water. It was washed and dried in an oven at 80\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 12 hours.\u003c/p\u003e\n\u003cp\u003eIn the next step, 500 mg of oxidized nanodiamonds was mixed in 20 ml of distilled water and dispersed for 20 minutes. then 0.7 g FeCl\u003csub\u003e3\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003eO and 0.4 g FeCl\u003csub\u003e2\u003c/sub\u003e.4H\u003csub\u003e2\u003c/sub\u003eO in 80 ml of water were added to the diamond nanoparticles, and then 10 ml of ammonium hydroxide was added drop by drop under the conditions of 80\u0026deg;C for 40 minutes. was added to the mixture and the reaction was terminated after 3 hours. After the reaction, the nanoparticles were separated using an external magnet and washed with water and ethanol in several steps and at a temperature of 80\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 24 hours.\u003c/p\u003e\n\u003cp\u003e500 mg of magnetized nanodiamond was dispersed in 100 ml of deionized water for 20 minutes, and then 100 ml of pectin solution with 100 ml of deionized water was added drop by drop to the reaction mixture and in 5 hours at 70\u003csup\u003e\u0026deg;\u003c/sup\u003eC was stirred. Finally, the reaction precipitate was removed using an external magnet, and washed with water and ethanol in several steps and at a temperature of 60\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 48 hours.\u003c/p\u003e\n\u003cp\u003eIn the last step, 400 mg of nanocomposite was dispersed in 50 ml of deionized water for 20 minutes, then 20 ml of 0.02 M AgNO\u003csub\u003e3\u003c/sub\u003e was added to the mixture for 30 minutes, and then 25 ml of 0. 1 M NaBH\u003csub\u003e4\u003c/sub\u003e was added to the mixture for 30 minutes and then it was separated using an external magnet and washed with water and ethanol in several steps and dried at 80\u003csup\u003e\u0026deg;\u003c/sup\u003eC for 24 hours.\u003c/p\u003e\n\u003ch3\u003e\u003cem\u003eGeneral procedure for the synthesis of 2‑amino‑4H‑pyran 5a‑l derivatives catalyzed by ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag\u003c/em\u003e\u003c/h3\u003e\n\u003cp\u003eIn a 5 ml round-bottomed fask, a mixture of methyl or ethyl acetoacetate \u003cstrong\u003e2\u003c/strong\u003e (1 mmol), aromatic aldehyde \u003cstrong\u003e3\u003c/strong\u003e (1 mmol), malononitrile \u003cstrong\u003e4\u003c/strong\u003e (1 mmol) and ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag \u003cstrong\u003e1\u003c/strong\u003e (10 mg) were added in a 5 ml round-bottomed fask. The obtained mixture was mechanically stirred at room temperature for appropriate time indicated in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. Afer completion of the reaction, which was confrmed by thin layer chromatography (TLC), hot EtOH (5 ml) was added After completion of the reaction, the catalyst was separated easily by an external magnet and the product was allowed at room temperature to precipitate pure product. the recycled catalyst 1 was kept in an oven at 50\u0026deg;C for one hour and then reused for the next runs. All the product were known compounds which were identified by characterization of their melting points (as indicated in Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e) by comparison with those authentic literature samples and also in some cases their FT-IR, \u003csup\u003e1\u003c/sup\u003eH NMR spectral data.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSpectroscopic data for 4-(4-chlorophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate (\u003c/em\u003e \u003cstrong\u003e5a\u003c/strong\u003e \u003cem\u003e)\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eM.p. 170\u0026ndash;171\u0026deg;C; IR (KBr, \u0026upsilon;, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e): 3394, 3325, 3215, 2960,2190, 1683, 1656, 1605; \u003csup\u003e1\u003c/sup\u003eH NMR (500 MHz, DMSO-d6): \u0026delta; 2.32 (s, 3H, CH\u003csub\u003e3\u003c/sub\u003e), 3.59 (s, 3H, CH\u003csub\u003e3\u003c/sub\u003e), 4.19 (s, 1H, CH-), 7.06 (s, 2H, -NH\u003csub\u003e2\u003c/sub\u003e), 7.15\u0026ndash;7.17 (d, 2H, ArH), 7.32\u0026ndash;7.34 (d, 2H, ArH).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSpectroscopic data for 4-(3-nitrophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate (\u003c/em\u003e \u003cstrong\u003e5d\u003c/strong\u003e \u003cem\u003e)\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eM.p. 211\u0026ndash;213\u0026deg;C; IR (KBr, \u0026upsilon;, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e): 3450, 3309, 3191, 2962, 2189, 1670, 1650,1583; \u003csup\u003e1\u003c/sup\u003eH NMR (500 MHz, DMSO-d6): \u0026delta; 2.26 (s, 3H, CH\u003csub\u003e3\u003c/sub\u003e), 3.65 (s, 3H, CH\u003csub\u003e3\u003c/sub\u003e), 4.41 (s, 1H, CH-), 7.18 (s, 2H, -NH\u003csub\u003e2\u003c/sub\u003e), 7.60 (m, 1H, ArH), 7.65\u0026ndash;7.66 (d, 1H, ArH), 7.97 (s, 1H, ArH), 8.05\u0026ndash;8.07 (d, 1H, ArH).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors gratefully acknowledge the partial support from the Research Council of the Iran University of Science and Technology.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eSupporting Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAdditional supporting information including spectroscopic characterization data of the nanocatalyst and the products such as FT-IR and \u003csup\u003e1\u003c/sup\u003eH NMR can be found in the online version of this article at the publisher\u0026rsquo;s web site.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data that support the findings of this study are included within the article and supplementary files.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eMochalin, V., Shenderova, O., Ho, D. and Gogotsi, Y. 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Efficient and Green Synthesis of 4H-pyrans and 4H-pyrano [2, 3-c] Pyrazoles Catalyzed by Task-specific Ionic Liquid [bmim] OH under Solvent-free Conditions. \u003cem\u003eGreen Chemistry Letters and Reviews\u003c/em\u003e. \u003cstrong\u003e5\u003c/strong\u003e, 633-638 (2012).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table 1","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e"},{"header":"Schemes","content":"\u003cp\u003eSchemes are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"biopolymer, ND/Fe3O4/Pectin-Ag, 4H-pyran, nanodiamond, multicomponent reaction, green synthesis","lastPublishedDoi":"10.21203/rs.3.rs-6862912/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6862912/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis research introduces a novel biopolymer nanocatalyst, ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag, supported by nanodiamonds, for the one-pot, three-component synthesis of 2-amino-4H-pyran derivatives. The catalyst was characterized using various techniques by Fourier transforms infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FESEM), X-Ray diffraction analysis (XRD), inductively coupled plasma (ICP), Thermogravimetric analysis (TGA) and vibrating-sample magnetometer (VSM), confirming its successful synthesis and appropriate morphology. Compared to existing methods, ND/Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/Pectin-Ag offers advantages such as high efficiency (up to 98% yield), solvent-free conditions, room temperature operation, and potential reusability due to its magnetic properties. This work presents a promising green approach for the synthesis of biologically active heterocycles.\u003c/p\u003e","manuscriptTitle":"Green Synthesis of 2-Amino-4H-Pyran Derivatives Using a Novel Biopolymer Nanocatalyst ND/Fe3O4/Pectin-Ag","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-18 20:21:41","doi":"10.21203/rs.3.rs-6862912/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bd07a0c3-5b98-4306-8e38-cc6e6bc627f1","owner":[],"postedDate":"June 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":50261842,"name":"Physical sciences/Chemistry"},{"id":50261843,"name":"Physical sciences/Chemistry/Catalysis"},{"id":50261844,"name":"Physical sciences/Chemistry/Green chemistry"},{"id":50261845,"name":"Physical sciences/Chemistry/Organic chemistry"}],"tags":[],"updatedAt":"2026-02-02T13:11:17+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-18 20:21:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6862912","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6862912","identity":"rs-6862912","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}