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. 2019 Nov 12;4(24):20618–20633. doi: 10.1021/acsomega.9b02755

New Hydrogen-Bond-Enriched 1,3,5-Tris(2-hydroxyethyl) Isocyanurate Covalently Functionalized MCM-41: An Efficient and Recoverable Hybrid Catalyst for Convenient Synthesis of Acridinedione Derivatives

Zahra Alirezvani 1, Mohammad G Dekamin 1,*, Ehsan Valiey 1
PMCID: PMC6906789  PMID: 31858048

Abstract

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A new nano-ordered 1,3,5-tris(2-hydroxyethyl) isocyanurate-1,3-propylene covalently functionalized MCM-41 (MCM-41-Pr-THEIC) was designed and prepared at room temperature through a simple procedure. According to various microscopic, spectroscopic, or thermal methods and techniques, the correlation of the catalytic performance of the hybrid mesoporous MCM-41-Pr-THEIC to its structural characteristics was fully confirmed. The new MCM-41-Pr-THEIC organosilica nanomaterials were successfully investigated as a solid mild nanocatalyst through hydrogen-bonding activation provided by its organic moiety, for the pseudo-four-component condensation of dimedone, aldehydes, and ammonium acetate or p-toluidine to afford the corresponding acridinedione derivatives under green conditions. Furthermore, the introduced nanocatalyst could be reused at least four times with negligible loss of its activity, indicating the good stability and high activity of the new hybrid organosilica.

Introduction

Organocatalysis has been emerged as an environmental and cost-effective alternative pathway to the traditional transition-metal catalysis for fine chemical synthesis especially in pharmaceutical industry over recent decades.1−9 Perfect homogeneous organocatalyst must be available through easy synthetic procedures and are often composed of nontoxic small organic compounds that can be easily degraded in the environment without significant waste generation.5,10−13 However, the usual workup remains a major drawback with tedious and costly procedures for separation of the homogeneous organocatalysts from the reaction mixture. On the other hand, heterogeneously catalyzed procedures have a valuable role in simplification of the processes and decreasing environmental concerns, including less corrosion, simple separation, catalysts recovery, and avoiding the usage of hazardous solvents.14−16 To achieve more sustainable catalytic progresses by improving the yield and energy efficiency, recent contributions have also been focused on immobilized organocatalysts onto the surface of solid polymeric supports, in particular silica.17−24 The structure of the obtained organosilica materials is sufficiently attractive and tunable to combine the advantages of a silica matrix, including high surface area, thermal or mechanical stability, as well as chemical inertness with the properties of the grafted organic moieties.22,25−32 Hence, mesoporous silica-based materials (MCM) with very large specific surface areas (up to 2000 m2 g–1) and tunable pore radius from approximately 2–50 nm as well as mechanically stable structure have become a new possible candidate for sensors,33 adsorbents,34−36 drug-delivery systems,35,37,38 and CO2 capture or transformation,39,40 as well as solid supports to immobilize homogeneous catalysts41−46 or directly use them as an ideal heterogeneous catalyst alone.47−53

On the other hand, multicomponent reactions (MCRs) have received great interest from synthetic, environmental, and economical points of view in recent years, especially for the synthesis of heterocycles with high diversity such as acridinedione derivatives.45,54−62 These tricyclic N-containing heterocycles have received a lot of interest as one of the most important classes of heterocyclic scaffolds in the biologically active molecules research. A series of acridinediones containing aromatic substituents are generally known as antibacterial or antiparasitic agents that are capable of intercalating into DNA base pairs.63 Furthermore, there are several pharmacological properties associated with these compounds, including antimalarial,64 antifungal,65 anticancer,66 or GCN5 inhibitor67 properties as well as selective flouride-ion chemosensor68 and fluorescence enhancement.69 Due to the biological importance of the acridinedione derivatives, synthesis of these compounds is an interesting research challenge for both organic and medicinal chemists.70,71 Literature survey shows that several modified methods for the pseudo-four-component Hantzsch-type condensation of aromatic aldehydes, dimedone, and different nitrogen sources, including urea, methyl amine, aniline, or ammonium acetate, have been reported using different catalytic systems by the traditional heating in organic solvents72 or under microwave irradiation.73,74 Recently, ZnII doped and immobilized on functionalized magnetic hydrotalcite,75 platinum nanoparticles supported on graphene oxide or its reduced form,76 carboxylic acid-functionalized multiwalled carbon nanotubes,77 TiO2-coated magnetite nanoparticle-supported sulfonic acid,78,79 sulfuric acid-modified poly(vinylpyrrolidone),80 SnCl4-functionalized nano-Fe3O4-encapsulated silica,13 Eu2O3-modified CeO2 nanoparticles,81 Vitamin B1,82 morpholinium-based ionic liquids,68 and choline chloride:urea83 have been described. Although various protocols for the synthesis of acridinedione derivatives have been reported, the use of solid mild materials with simpler experimental setup; lower toxicity, corrosion, or cost; and environmental tolerability is still in demand. At present, it is worth using highly thermally stable, cost-effective, and milder catalytic systems for different organic transformations. In continuation of our ongoing efforts toward expanding efficient and novel heterogeneous catalysts for different MCRs,29,84−89 we wish herein to report the preparation and characterization of 1,3,5-tris(2-hydroxyethyl)isocyanurate covalently functionalized MCM-41 (MCM-41-Pr-THEIC, 1) nanocatalyst and examination of its catalytic activity for the pseudo-four-component condensation reaction of dimedone (2), different aldehydes 3, and ammonium acetate (4a) or p-toluidine (4b) to afford the corresponding Hantzsch acridinedione derivatives 5–6 under mild conditions in high to excellent yields and short reaction times (Scheme 1). This nanocatlyst can be considered as a typical example of mild heterogeneous catalysts which activate the substrates and intermediates during the catalytic cycle through hydrogen bonding provided by its organic moiety as well as inorganic silica support whose polarity has been appropriately balanced. To the best of our knowledge, there is no report for the use of 1,3,5-tris(2-hydroxyethyl)isocyanurate grafted on the surface of MCM-41 by 1,3-propylene linker (MCM-41-Pr-THEIC) as a heterogeneous organocatalyst, for different MCRs including Hantzsch acridinedione derivatives 5 or 6.

Scheme 1. Schematic Preparation of the Novel Nano-Ordered 1,3,5-Tris(2-hydroxyethyl) Isocyanurate-1,3-propylene Covalently Functionalized MCM-41 (MCM-41-Pr-THEIC) (MCM-41-Pr-THEIC, 1) and Its Application for the Synthesis of Acridinedione Derivatives 5–6.

Scheme 1

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Results and Discussion

Characterization of the Covalently Modified Nano-Ordered MCM-41 Using 1,3-Dibromopropane and THEIC (MCM-41-Pr-THEIC, 1)

Initially, the MCM-41-Pr-THEIC materials (1) were prepared by grafting of the 1,3,5-tris(2-hydroxyethyl)isocyanurate to the surface of the nano-ordered MCM-41 using 1,3-dibromopropne, as an appropriate and inexpensive linker (Scheme 1). The surface and bulk properties of the new catalyst were studied by several techniques such as Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), derivative thermogravimetry, energy-dispersive X-ray (EDX) spectroscopy, and CHN elemental analysis.

The preparation of the MCM-41-Pr-THEIC materials (1) and their structure were approved by FTIR spectroscopy. The FTIR spectra of MCM-41 (a), MCM-41-PrBr (b), MCM-41-Pr-THEIC (1, c), MCM-41-Pr-THEIC after four times of recycling (d), and THEIC (e) are compared in Figure 1. It is generally approved that high-intensity bands at 1180–1278 cm–1 are due to the asymmetrical Si–O external stretching vibrations and those at 1000–1100 cm–1 are due to the internal vibrations.90 Moreover, the signals appearing at 1689 and 1471 cm–1 are attributed to the stretching vibrations of the isocyanurate ring. Also, the observed characteristic bands at 3200–3400 cm–1 are attributed to the stretching vibration of the O–H bonds of both MCM-41 and THEIC.

Figure 1.

Figure 1

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FTIR spectra of MCM-41 (a), MCM-41-PrBr (b), MCM-41-Pr-THEIC (1, c), MCM-41-Pr-THEIC after four times of recycling (d), and THEIC (e).

The field emission scanning electron microscopy (FESEM) images illustrated in Figure 2a–f reveal the general morphology of MCM-41 and MCM-41-Pr-THEIC (1). As it can be found from the FESEM images of MCM-41-Pr-THEIC (1, Figure 2d–f), the morphological structure of the MCM-41-Pr-THEIC (1) materials is different from that of the pure MCM-41; moreover, the particles size of MCM-41-Pr-THEIC (1) is slightly higher than that of pure MCM-41 (12.1–16.5 nm). On the other hand, the transmission electron microscopy (TEM) images shown in Figure 3 confirms the presence of 1,3,5-tris(2-hydroxyethyl)isocyanurate grafted to the 1,3-propylene linker in the channels of the nanosized MCM-41-Pr-THEIC (1) sample compared to pure MCM-41.91,92

Figure 2.

Figure 2

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FESEM images of the MCM-41 (a–c) and the MCM-41-Pr-THEIC (1) nanomaterials (d–f).

Figure 3.

Figure 3

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TEM images of the MCM-41-Pr-THEIC (1) nanomaterials.

The thermal stability of the MCM-41-Pr-THEIC nanomaterials (1) was also investigated using the thermogravimetric analysis (TGA) technique (Figure 4). The TGA curve of the MCM-41-Pr-THEIC (1) shows three steps of weight loss. The 7% weight loss in the first step corresponds to desorption of physiosorbed water or solvent molecules held in the pores of MCM-41-Pr-THEIC (1). Furthermore, the sharp 46% weight loss in the second step (between 200 and 400 °C) can be mainly attributed to the decomposition of 2-hydroxyethyl moiety existing in the structure of THEIC or 1,3-propylene linker in the nanomaterial 1 framework. On the other hand, the slight 13% weight loss at >400 °C was related to the decomposition of thermally stable isocyanurate ring located on the surface of MCM-41 channels.29,86,93,94 These results also indicate that 1,3,5-tris(2-hydroxyethyl)isocyanurate has been successfully grafted onto the surface of MCM-41.95

Figure 4.

Figure 4

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TGA of the MCM-41-Pr-THEIC (1) nanomaterials.

The CHN analysis of functionalized MCM-41 with THEIC 1 was also used to quantify the organic molecules anchored to its surface. The percentage of nitrogen was observed to be 2.46%w. This means that loading of the 1,3,5-tris(2-hydroxyethyl)isocyanurate per gram of the MCM-41-Pr-THEIC (1) is about 0.59 mmol. Furthermore, EDX analysis of MCM-41-Pr-THEIC (1) clearly confirmed the presence of C, N, O, and Si (Figure 5). These findings, especially the presence of nitrogen and absence of halogen impurity in the composition of the nanomaterials 1, demonstrate grafting of the 1,3,5-tris(2-hydroxyethyl) isocyanurate onto the surface of the MCM-41 matrices. Indeed, EDX and CHN analyses show a good agreement with those data obtained in TGA as well as FESEM and TEM images, which strongly confirm the successful functionalization of inorganic MCM-41 by the 1,3,5-tris(2-hydroxyethyl)isocyanurate organic moiety.

Figure 5.

Figure 5

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Energy-dispersive X-ray (EDX) spectroscopy pattern of the MCM-41-Pr-THEIC (1) materials.

On the other hand, Figure 6 shows the X-ray diffraction (XRD) patterns of MCM-41-Pr-THEIC (1). It is obvious that the characteristic highly ordered uniform hexagonal mesopores of MCM-41 still exist in the MCM-41-Pr-THEIC (1) nanomaterials (Figure 6, top). Furthermore, other peaks in the high-angle region of the XRD pattern can be attributed to the presence of 1,3,5-tris(2-hydroxyethyl)isocyanurate covalently grafted through the 1,3-propylene linker onto the surface of MCM-41 (Figure 6, down).

Figure 6.

Figure 6

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X-ray diffraction (XRD) patterns of MCM-41-Pr-THEIC (1) materials in the small-angle region (top) and the wide-angle region (down).

As shown in Figure 7, the adsorption–desorption isotherm of the MCM-41-Pr-THEIC (1) sample corresponds to a type V isotherm with H2 hysteresis loop according to the classification of Brunauer, Deming, Deming, and Teller. It is generally accepted that there is a correlation between the shape of the hysteresis loop and the texture (e.g., pore size distribution, pore geometry, and connectivity) of a mesoporous material.96 Indeed, grafting of THEIC groups through 1,3-propylene linker onto the surface of pore walls of MCM-41 can block them, leading to the decrease of surface area and broad pore distribution.

Figure 7.

Figure 7

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Adsorption/desorption isotherm of the MCM-41-Pr-THEIC (1) materials.

Investigation of the Catalytic Activity of MCM-41-Pr-THEIC (1) for the Synthesis of Acridinediones 5–6

To evaluate the catalytic activity of MCM-41-Pr-THEIC (1) for the synthesis of acridinediones 5–6, the pseudo-four-component condensation of 4-chlorobenzaldehyde (3a, 1.0 mmol), dimedone (2, 2.0 mmol), and ammonium acetate (4a, 1.2 mmol) or p-toluidine (4b, 1.0 mmol) was investigated as the model reaction. In a systematic study, the effects of several crucial variables such as solvent and temperature, catalyst loading, and reaction time were studied. The results are summarized in Table 1. In the first step, to optimize the reaction conditions, a variety of solvents and temperatures were screened in the model reaction. In the absence of any solvent, the model reaction was slow and the yield of the desired product 9-(4-chlorophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione (5a) was low to moderate, even at 120 °C and after 1.5 h (Table 1, entry 1). The model reaction was then studied in solvents such as H2O, EtOH, MeOH, THF, EtOAc, CH3CN, EtOH/H2O (1:1), EtOH/H2O (2:1), and EtOH/H2O (1:2) using MCM-41-Pr-THEIC (1) 20 mg loading (entries 2–14). The results clearly indicated that the model reaction did not proceed substantially at room temperature (Table 1, entries 2, 8, and 10). Interestingly, higher yield of the desired product 5a was obtained in EtOH/H2O (1:2) under reflux conditions (Table 1, entry 15). Encouraged by this result, the model reaction was examined in EtOH/H2O (1:2) under reflux conditions using different amounts of catalyst loading (entries 15–19). To our delight, it was found that 15 mg of catalyst 1 was sufficient to promote the model reaction efficiently (entry 15). On the other hand, to demonstrate the synergic impact of hydroxyl functional groups of MCM-41 and 1,3,5-tris(2-hydroxyethyl) isocyanurate on the catalytic activity of nanomaterial 1, the catalytic performances of MCM-41, MCM-41-PrBr, or 1,3,5-tris(2-hydroxyethyl) isocyanurate were also examined under the same reaction conditions (Table 1, entries 20–22). Indeed, the results strongly confirmed the role of all MCM-41-Pr-THEIC (1) components to promote the synthesis of acridinedione 5a. Therefore, MCM-41-Pr-THEIC (1, 15 mg) in EtOH/H2O (1:2, 2 mL) under reflux conditions as the optimized reaction conditions were developed to other aromatic aldehydes (3b–j) for the synthesis of a wide range of the desired products 5–6. The results are summarized in Table 2.

Table 1. Optimization of Conditions in the Reaction of Dimedone (2), 4-Chlorobenzaldehyde (3a), Ammonium Acetate (4a) or p-toluidine (4b) under Different Conditionsa.

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entry catalyst catalyst loading (mg) solvent temperature (°C) time (min) yieldb (%) 5a yieldb (%) 6a
1 MCM-41-Pr-THEIC 20   120 90 76 80
2 MCM-41-Pr-THEIC 20 EtOH rt 180 30 36
3 MCM-41-Pr-THEIC 20 EtOH reflux 90 60 69
4 MCM-41-Pr-THEIC 20 MeOH reflux 180 50 58
5 MCM-41-Pr-THEIC 20 EtOAc reflux 180 42 49
6 MCM-41-Pr-THEIC 20 THF reflux 180 39 53
7 MCM-41-Pr-THEIC 20 CH3CN reflux 120 56 62
8 MCM-41-Pr-THEIC 20 H2O rt 180 38 45
9 MCM-41-Pr-THEIC 20 H2O reflux 90 70 78
10 MCM-41-Pr-THEIC 20 EtOH/H2O (1:1) rt 150 40 48
11 MCM-41-Pr-THEIC 20 EtOH/H2O (1:1) 50 100 78 83
12 MCM-41-Pr-THEIC 20 EtOH/H2O (1:1) reflux 40 85 91
13 MCM-41-Pr-THEIC 20 EtOH/H2O (2:1) reflux 60 80 85
14 MCM-41-Pr-THEIC 20 EtOH/H2O (1:2) reflux 35 89 92
15 MCM-41-Pr-THEIC 15 EtOH/H2O (1:2) reflux 45 90 92
16 MCM-41-Pr-THEIC 10 EtOH/H2O (1:2) reflux 60 82 86
17 MCM-41-Pr-THEIC 5 EtOH/H2O (1:2) reflux 90 76 77
18 MCM-41-Pr-THEIC 2 EtOH/H2O (1:2) reflux 120 57 65
19 MCM-41-Pr-THEIC 0 EtOH/H2O (1:2) reflux 180 36 40
20 MCM-41 20 EtOH/H2O (1:2) reflux 60 76 84
21 MCM-41-Pr 20 EtOH/H2O (1:2) reflux 60 70 79
22 1,3,5-tris(2-hydroxyethyl) isocyanurate 20 EtOH/H2O (1:2) reflux 90 68 79
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a

Reaction conditions: Dimedone (2, 2 mmol), 4-chlorobenzaldehyde (3a, 1 mmol), ammonium acetate (4a, 1.2 mmol), or p-toluidine (4b, 1 mmol), MCM-41-Pr-THEIC (1), and solvent (2 mL).

b

Isolated yields.

Table 2. Scope of the Synthesis of 9-(aryl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione Derivatives 5a–j and 6a–j Catalyzed by MCM-41-Pr-THEIC (1) via the Pseudo-Four-Component Reaction Strategya,b,c97−106.

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a

Reaction conditions: Dimedone (2, 2 mmol), aryl aldehydes (3, 1 mmol), ammonium acetate (4a, 1.2 mmol), or p-toluidine (4b, 1 mmol) and the MCM-41-Pr-THEIC (1, 15 mg) in EtOH/H2O (1:2) at reflux condition.

b

All products, except 6J, are known and their structures were established from their spectral data and melting points compared to authentic samples or literature values.

c

Isolated yields were reported.

The obtained results showed that aldehydes 3 having an electron-withdrawing group on their aromatic ring generally reacted faster or afforded higher yields compared to those with an electron-donating group. It is also significant that even ortho-substituted benzaldehydes, considering their intrinsic steric hindrance, afforded the desired products in high yields under optimized conditions. These observations strongly approve the appropriate catalytic activity of MCM-41-Pr-THEIC (1) to promote the Hantzsch pseudo-four-component reaction of different aldehydes 3, dimedone (2), and nitrogen sources 4a–b.

According to the obtained results, the above mechanism can be proposed for the synthesis of acridinediones 5–6 catalyzed by MCM-41-Pr-THEIC (1) through the MCR strategy (Scheme 2). In the first step, MCM-41-Pr-THEIC (1) activates the carbonyl functional group of both dimedone (2) and aldehydes 3, through hydrogen bonding made by hydroxyl groups of THEIC or silanol groups on the surface of MCM-41, to form the corresponding Knoevenagel intermediate (II). This intermediate is further activated by MCM-41-Pr-THEIC (1) to be involved for the next Michael addition of the enol form of dimedone 2. The next step comprises the formation of intermediate IV from the second equivalent of dimedone 2. Then, one of the keto functional groups in the intermediate IV is activated by MCM-41-Pr-THEIC (1) to react with the ammonia source 4 affording imine intermediate V. The cyclization between enamine and keto functional group, followed by proton transfer, and finally elimination of third H2O molecules affords the desired acridinediones 5–6.53,107−112 Indeed, the THEIC moiety attached by 1,3-propylene linker appropriately modifies the surface of MCM-41 for a prompt catalytic activity of MCM-41-Pr-THEIC nanomaterials (1). Moreover, the byproduct water molecules can be simply adsorbed on the surface of MCM-41-Pr-THEIC nanomaterials (1).

Scheme 2. Probable Mechanism for the Hantzsch Pseudo-Four-Component Reaction of Different Aldehydes 3, Dimedone (2), and Nitrogen Sources 4a–b Catalyzed by MCM-41-Pr-THEIC (1).

Scheme 2

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On the other hand, reusability of a heterogeneous catalyst is a significant feature for its industrial applications. Therefore, the recycled MCM-41-Pr-THEIC (1) was washed with acetone to remove any organic impurities and then heated in an oven to be reused in the model reactions for the next run. This procedure was repeated for three more consecutive runs (Figure 8). It was found that the reactivity of catalyst 1 for the Hantzsch pseudo-four-component synthesis of acridinedione derivatives 5a and 6a decreases slightly (approximately 8%) after five runs. The latest isolated yields of 5a or 6a after four times of catalyst recycling were 82 and 84%, respectively.

Figure 8.

Figure 8

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Reusability of the heterogeneous nanocatalyst MCM-41-Pr-THEIC (1) for the synthesis of 5a (orange charts) and 6a (gray charts).

To demonstrate the appropriate catalytic activity of the new hybrid heterogeneous nano-ordered catalyst MCM-41-Pr-THEIC (1), its performance has been compared to that of some recently reported catalytic systems for the synthesis of acridinedione derivatives 5a and 6a. The summarized results in Table 3 obviously show that some of the reported catalysts are homogeneous and cannot be reused. Furthermore, the present protocol provides better performance in terms of product yield, catalyst loading, reaction time, operational simplicity, and frequency of recycling compared to most of previously published catalytic systems.

Table 3. Comparison of Catalytic activities of MCM-41-Pr-THEIC (1) and Other Catalysts for the Synthesis of Products 5a or 6a.

entry catalyst product catalyst loading conditions time (min) yield (%) catalyst reuse times reference
1 β-cyclodextrin monosulfonic acid 5a 30 mg H2O/60°C 120 91 5 (113)
2 ascorbic acid 5a 8.8 mg solvent-free/80 °C 180 89   (114)
3 SnCl4-functionalized nano-Fe3O4-encapsulated silica 5a 25 mg EtOH/reflux 15 93 4 (13)
4 TiO2-coated magnetite nanoparticle-supported sulfonic acid 5a 10 mg solvent-free/110 °C 40 95 5 (78)
5 Fe3O4@TiO2@O2PO2(CH2)2NHSO3H 5a 7 mg solvent-free/90 °C 25 92 4 (79)
6 1-n-butyl-3-methylimidazolium bromide ([bmim]Br) 5a 10 mL (Excess) 90 °C 40 93   (115)
7 ZnII-doped and immobilized on functionalized magnetic hydrotalcite 5a 8 mg solvent-free/70 °C 5 90 6 (75)
8 MCM-41-Pr-THEIC 5a 15 mg EtOH/H2O (1:2)/reflux 45 91 5 this work
9 1-n-butyl-3-methylimidazolium bromide ([bmim]Br) 6a 10 mL 90 °C 120 96   (115)
10 carbon-based solid acid 6a 30 mg 100 °C solvent-free 30 88 3 (116)
11 fluorous silica gel-supported hafnium(IV) bis(perfluorooctanesulfonyl) imide complex 6a 1 mol % EtOH/H2O (1:1)/reflux 390 66 3 (117)
12 polyvinylpolypyrrolidone-supported boron trifluoride: 6a 100 mg CH3CN reflux 210 97 4 (118)
13 MCM-41-Pr-THEIC 6a 15 mg EtOH/H2O (1:2)/reflux 45 92 5 this work
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Conclusions

In summary, we have developed a novel and powerful 1,3,5-tris(2-hydroxyethyl)isocyanurate covalently functionalized nano-ordered MCM-41 (MCM-41-Pr-THEIC) as a robust and recoverable catalyst for the pseudo-four-component condensation of dimedone, aldehydes, and ammonium acetate or p-toluidine to afford the acridinedione derivatives under extremly green conditions. The notable advantages of this method are clean reaction profiles, short reaction time, and high to quantitative yields without using precious or toxic metals and hazardous organic solvents, which makes it an improved and more practical alternative to the existing methods. Additionally, the catalyst could be simply separated and reused without apparent loss of its activity at least after four cycles. Due to the notable advantages of the MCM-41-Pr-THEIC nanocatalyst, its applications in other organic reactions are currently underway in our lab and would be reported in due course.

Experimental Section

Reagents and Apparatus

All chemicals were purchased from Merck or Aldrich with the highest purity available, and benzaldehyde was used as a freshly distilled sample. The morphological, structural, and compositional characterizations of the nanocatalyst 1 were properly carried out using FESEM TESCAN-MIRA3, EDX Numerix DXP-X10P, Philips CM30, Shimadzu FTIR-8400S, TGA Bahr company STA 504, and CHN Elemental instruments. Characterization of introduced nanocatalyst 1 was performed by transmission electron microscopy (TEM, Philips CM30). A Shimadzu FTIR-8400S spectrometer and a Bruker DRX-500 Avance spectrometer (ambient temperature in DMSO-d6) were used for recording FTIR, 1H NMR (500 MHz), and 13C NMR (125 MHz) spectra of products. The analytical thin-layer chromatography (TLC) experiments were performed using Merck 0.2 mm silica gel 60 F-254 Al-plates for observation progress of reactions. All melting points were determined using a digital Electrothermal 9100 capillary melting point apparatus. The isolated yields of products have been reported. All of the products, except 6J, are known compounds, and their physical, analytical, and spectroscopic data were in agreement with the authentic samples.

Typical Procedure for Preparation of MCM-41

MCM-41 materials were prepared by direct hydrothermal synthesis according to a known procedure as follows: In a general procedure, dimethylamine (60 mmol, 2.70 g) was added to deionized water (42 mL) in a 200 mL beaker while the mixture was stirred at room temperature. Then, CTAB (4 mmol, 1.47 g) was added to the above solution to obtain a clear solution after stirring for 30 min. Tetraethyl orthosilicate (10 mmol, 2.10 g) was then added into the mixture with stirring. By dropwise addition of HCl solution (1 M), the pH of the mixture was adjusted to 8.5, to obtain a final precipitate. After 2 h stirring, white precipitates were obtained, which were filtered, washed with deionized water, dried at 45 °C, and calcined at 550 °C for 45 h to remove the residual CTAB template.45

General Procedure for Preparation of the MCM-41-Pr-THEIC (1) nanomaterials

In a 200 mL round-bottom flask, 1,3-dibromopropane (49 mmol, d = 1.98 g cm–3, 5 mL) was added to a suspension containing MCM-41 (1.0 g) in dry toluene (30 mL). Then, the mixture was stirred continuously at room temperature for 18 h. After this time, the obtained solids were filtered and washed with toluene and EtOH several times to remove any excess of the linker. Next, dried white solids (1.0 g) were dispersed in dry toluene (30 mL). Following this, THEIC (3.82 mmol, 1.8 g), K2CO3 (4.0 mmol, 0.6 g), and KI (0.12 mmol, 0.02 g) were added to the obtained mixture, respectively. The mixture was stirred at a constant rate at room temperature for 10 h. Then, the obtained solids were filtered off and washed with toluene and EtOH for several times. Finally, the residues were dried in a vacuum drying oven at 60 °C for 8 h. The schematic route for the preparation of MCM-41-Pr-THEIC (1) nanomaterials is shown in Scheme 1.

General Procedure for the Synthesis of Acridinedione Derivatives (5a–j, 6a–j) Catalyzed by the MCM-41-Pr-THEIC (1) Nanomaterials

In a 5 mL round-bottom flask, dimedone (2, 1 mmol), aldehyde (3a–j, 1 mmol), NH4OAc (4a, 1.2 mmol) or p-toluidine (4b, 1 mmol), and MCM-41-Pr-THEIC (1, 15 mg) were added to EtOH 96%:H2O (1:2, 2 mL). The obtained mixture was stirred and heated under reflux conditions for the times indicated in Table 2. The progress of the reactions was monitored by TLC (eluent: EtOAc:n-hexane, 1:3). After completion of the reaction, 96% EtOH (2 mL) was added and the mixture was heated to dissolve any solid products 5–6 and the solid catalyst 1 remained insoluble. The catalyst was then separated by filtration and n-hexane (one to three drops) was added to the filtrate and then allowed to cool over time to give pure crystals of the desired acridinedione derivatives 5–6. The separated catalyst was suspended in acetone (1 mL), stirred for 30 min, and then filtered off. The residue white powder was then heated in an oven at 60 °C for 1.5 h and reused for successive runs.

Selected Spectral Data

9-(4-Chlorophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione (5a)

Mp: 243–245 °C; IR (KBr): ν 3288, 3205, 3068, 2956, 2869, 1643, 1608, 1485, 1363, 1223, 1131 cm–1; 1H NMR (500 MHz, DMSO-d6): δ 0.85 (s, 6H), 0.99 (s, 6H), 1.96–1.99 (d, J = 12.8 Hz, 2H), 2.15–2.18 (d, J = 12.8 Hz, 2H), 2.30–2.33 (d, J = 14.9 Hz, 2H), 2.49-2.46 (d, J = 14.9 Hz, 2H), 4.77 (s, 1H, C–Hbenzylic), 7.15–7.20 (m, 4H, Haromatic), 9.33 (br s, 1H, N–H) ppm.

9-(4-Methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione (5e)

Mp: 275 °C; IR (KBr): ν 3277, 3205, 3082, 2929, 2870, 1663, 1508, 1397, 1223, 1171 cm–1; 1H NMR (500 MHz, DMSO-d6): δ 0.86 (s, 6H), 1.00 (s, 6H), 1.96–1.98 (d, J = 16.1 Hz, 2H), 2.14–2.17 (d, J = 16.1 Hz, 2H), 2.29–2.32 (d, J = 17.1 Hz, 2H), 2.44-2.41 (d, J = 17.1 Hz, 2H), 3.65 (s, 3HMethoxy), 4.74 (s, 1H, C–Hbenzylic), 6.71-6.69 (d, J = 8.4 Hz, 2H), 7.03–7.05 (d, J = 8.4 Hz, 2H), 9.24 (br s, 1H, N–H) ppm.

3,3,6,6-Tetramethyl-9-(p-tolyl)-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione (5g)

Mp: >300 °C; IR (KBr): ν 3350, 3298, 3099, 3001, 2883, 1663, 1603, 1502, 1401, 1356, 1213, 1131 cm–1; 1H NMR (500 MHz, DMSO-d6): δ 0.85 (s, 6H), 0.99 (s, 6H), 1.95–1.98 (d, J = 16.1 Hz, 2H), 2.13–2.17 (m, 5H(2H + CH3)), 2.28–2.32 (d, J = 17.1 Hz, 2H), 2.45-2.41 (d, J = 17.1 Hz, 2H), 4.75 (s, 1H, C–Hbenzylic), 6.93-6.4 (d, J = 7.5 Hz, 2H), 7.01–7.03 (d, J = 7.6 Hz, 2H), 9.24 (br s, 1H, N–H) ppm.

3,3,6,6-Tetramethyl-9-(pyridin-4-yl)-10-(p-tolyl)-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione (6j)

Mp: 278–280 °C; IR (KBr): ν 3075, 2945, 2901, 1659, 1567, 1370, 1213,1131 cm–1; 1H NMR (500 MHz, DMSO-d6): δ 0.70 (s, 6H), 0.87 (s, 6H), 1.78–1.81 (d, J = 17.3 Hz, 2H), 2.00–2.03 (d, J = 15.9 Hz, 2H), 2.18−2.21 (m, 4H), 2.41 (s, 3H (CH3)), 5.04 (s, 1H, C–Hbenzylic), 7.28 (m, 4H), 7.39–7.40 (d, J = 5.5 Hz, 2H), 8.43 (d, 2H) ppm; 13C NMR (125 MHz, DMSO-d6): δ 21.28, 26.59, 29.64, 32.40, 32.51, 41.40, 112.02, 123.35, 136.07, 139.47, 149.86, 151.74, 154.60, 195.45 ppm.

Acknowledgments

The authors are grateful for the financial support from The Research Council of Iran University of Science and Technology (IUST), Tehran, Iran (Grant No 160/18517). They also acknowledge the support of the Iran Nanotechnology Initiative Council (INIC).

Supporting Information Available

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsomega.9b02755.

  • FTIR spectra of MCM-41, MCM-41-Pr-THEIC, and THEIC; FESEM images of MCM-41 and MCM-41-Pr-THEIC; TEM images of MCM-41-Pr-THEIC; TGA of MCM-41-Pr-THEIC; XRD patterns of MCM-41 and MCM-41-Pr-THEIC; BET analysis of MCM-41-Pr-THEIC; CHN elemental analysis of MCM-41-Pr-THEIC; and FTIR, 1H NMR, and 13C NMR spectra of the selected products (PDF)

The authors declare no competing financial interest.

This paper was published ASAP on November 12, 2019 with the image for Scheme 2 duplicated as Scheme 1. The corrected version was reposted on November 15, 2019.

Supplementary Material

ao9b02755_si_001.pdf (1.7MB, pdf)

References

  1. Wen-Zhao Zhang S. N.; Luo S.. Practical Asymmetric Organocatalysis. In Green Techniques for Organic Synthesis and Medicinal Chemistry; Cue W. Z. B. W., Ed.; Wiley-VCH, 2018. [Google Scholar]
  2. Wang N.; Xu J.; Lee J. K. The importance of N-heterocyclic carbene basicity in organocatalysis. Org. Biomol. Chem. 2018, 16, 8230–8244. 10.1039/C8OB01667D. [DOI] [PubMed] [Google Scholar]
  3. Jacobsen E. N.; MacMillan D. W. Organocatalysis. Proc. Natl. Acad. Sci. U.S.A. 2010, 107, 20618–20619. 10.1073/pnas.1016087107. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Shaikh I. R. Organocatalysis: key trends in green synthetic chemistry, challenges, scope towards heterogenization, and importance from research and industrial point of view. J. Catal. 2014, 2014, 1–35. 10.1155/2014/402860. [DOI] [Google Scholar]
  5. Basumatary G.; Mohanta R.; Bez G. l-Proline Derived Secondary Aminothiourea Organocatalyst for Synthesis of Coumarin Derived Trisubstituted Methanes: Rate Enhancement by Bifunctional Catalyst over Cooperative Catalysis. Catal. Lett. 2019, 4 10.1007/s10562-019-02809-4. [DOI] [Google Scholar]
  6. Xiong X.; Yi C.; Liao X.; Lai S. An Effective One-Pot Access to 2-Amino-4H-benzo[b]pyrans and 1,4-Dihydropyridines via γ-Cyclodextrin-Catalyzed Multi-Component Tandem Reactions in Deep Eutectic Solvent. Catal. Lett. 2019, 149, 1690–1700. 10.1007/s10562-019-02767-x. [DOI] [Google Scholar]
  7. Ullah M. S.; Itsuno S. Synthesis of cinchona alkaloid squaramide polymers as bifunctional chiral organocatalysts for the enantioselective Michael addition of β-ketoesters to nitroolefins. Mol. Catal. 2017, 438, 239–244. 10.1016/j.mcat.2017.06.010. [DOI] [Google Scholar]
  8. Shinde V. V.; Jeong D.; Jung S. Supramolecular aminocatalysis via inclusion complex: Amino-doped β-cyclodextrin as an efficient supramolecular catalyst for the synthesis of chromeno pyrimido[1,2-b]indazol in water. J. Ind. Eng. Chem. 2018, 68, 6–13. 10.1016/j.jiec.2018.08.010. [DOI] [Google Scholar]
  9. Ahankar H.; Ramazani A.; Ślepokura K.; Lis T.; Joo S. W. Synthesis of pyrrolidinone derivatives from aniline, an aldehyde and diethyl acetylenedicarboxylate in an ethanolic citric acid solution under ultrasound irradiation. Green Chem. 2016, 18, 3582–3593. 10.1039/C6GC00157B. [DOI] [Google Scholar]
  10. Ferré M.; Pleixats R.; Man M. W. C.; Cattoën X. J. G. C. Recyclable organocatalysts based on hybrid silicas. Green Chem. 2016, 18, 881–922. 10.1039/C5GC02579F. [DOI] [Google Scholar]
  11. Savateev A.; Antonietti M. Heterogeneous Organocatalysis for Photoredox Chemistry. ACS Catal. 2018, 8, 9790–9808. 10.1021/acscatal.8b02595. [DOI] [Google Scholar]
  12. Saravanan S.; Khan N.-u. H.; Kureshy R. I.; Abdi S. H.; Bajaj H. C. Small Molecule as a Chiral Organocatalyst for Asymmetric Strecker Reaction. ACS Catal. 2013, 3, 2873–2880. 10.1021/cs400742d. [DOI] [Google Scholar]
  13. Bamoniri A.; Fouladgar S. SnCl4-functionalized nano-Fe3O4 encapsulated-silica particles as a novel heterogeneous solid acid for the synthesis of 1,4-dihydropyridine derivatives. RSC Adv. 2015, 5, 78483–78490. 10.1039/C5RA12734C. [DOI] [Google Scholar]
  14. Argyle M.; Bartholomew C. Heterogeneous catalyst deactivation and regeneration: a review. Catalysts 2015, 5, 145–269. 10.3390/catal5010145. [DOI] [Google Scholar]
  15. Vojvodic A.; Nørskov J. K. New design paradigm for heterogeneous catalysts. Natl. Sci. Rev. 2015, 2, 140–143. 10.1093/nsr/nwv023. [DOI] [Google Scholar]
  16. Hernandez J. G.; Juaristi E. Recent efforts directed to the development of more sustainable asymmetric organocatalysis. Chem. Commun. 2012, 48, 5396–5409. 10.1039/c2cc30951c. [DOI] [PubMed] [Google Scholar]
  17. Macquarrie D. J.; Jackson D. B. Aminopropylated MCMs as base catalysts: a comparison with aminopropylated silica. Chem. Commun. 1997, 1781–1782. 10.1039/a704156j. [DOI] [Google Scholar]
  18. Gong Y.; Li Y.; Wu D.; Sun Y. Multiphasic Acetalization and Alkylation on Organically Modified MSU-X Silica. Catal. Lett. 2001, 74, 213–216. 10.1023/A:1016676929157. [DOI] [Google Scholar]
  19. Zhou Z.; Meng Q.; Seifert A.; Wagener A.; Sun Y.; Ernst S.; Thiel W. R. Hybrid mesoporous materials containing covalently anchored N-phenylthiazolium salts as organo catalysts. Microporous Mesoporous Mater. 2009, 121, 145–151. 10.1016/j.micromeso.2009.01.022. [DOI] [Google Scholar]
  20. Pérez-Quintanilla D.; Sánchez A.; Sierra I. Preparation of hybrid organic-inorganic mesoporous silicas applied to mercury removal from aqueous media: Influence of the synthesis route on adsorption capacity and efficiency. J. Colloid Interface Sci. 2016, 472, 126–134. 10.1016/j.jcis.2016.03.048. [DOI] [PubMed] [Google Scholar]
  21. Nakazawa J.; Doi Y.; Hikichi S. Alkane oxidation reactivity of homogeneous and heterogeneous metal complex catalysts with mesoporous silica-immobilized (2-pyridylmethyl) amine type ligands. Mol. Catal. 2017, 443, 14–24. 10.1016/j.mcat.2017.09.027. [DOI] [Google Scholar]
  22. White R. J.; Luque R.; Budarin V. L.; Clark J. H.; Macquarrie D. J. Supported metal nanoparticles on porous materials. Methods and applications. Chem. Soc. Rev. 2009, 38, 481–494. 10.1039/B802654H. [DOI] [PubMed] [Google Scholar]
  23. Yaghoubi A.; Dekamin M. G.; Arefi E.; Karimi B. Propylsulfonic acid-anchored isocyanurate-based periodic mesoporous organosilica (PMO-ICS-Pr-SO3H): A new and highly efficient recoverable nanoporous catalyst for the one-pot synthesis of bis(indolyl)methane derivatives. J. Colloid Interface Sci. 2017, 505, 956–963. 10.1016/j.jcis.2017.06.055. [DOI] [PubMed] [Google Scholar]
  24. Xu J.; Li K.; Zhang L.; Li H.; Wang T. SBA-15 Supported Organic Base Catalysts for Highly Effective Isomerization of Glucose to Fructose. J. Biobased Mater. Bioenergy 2019, 13, 739–747. 10.1166/jbmb.2019.1911. [DOI] [Google Scholar]
  25. Martínez-Edo G.; Balmori A.; Pontón I.; Martí del Rio A.; Sánchez-García D. Functionalized Ordered Mesoporous Silicas (MCM-41): Synthesis and Applications in Catalysis. Catalysts 2018, 8, 617 10.3390/catal8120617. [DOI] [Google Scholar]
  26. Bhaumik A.; Tatsumi T. Double organic modification by 3-chloropropyl and methyl groups on pure silica MCM-41 and Ti-MCM-41: efficient catalyst for epoxidation of cyclododecene. Catal. Lett. 2000, 66, 181–184. 10.1023/A:1019068127502. [DOI] [Google Scholar]
  27. Rostamnia S.; Doustkhah E. Nanoporous silica-supported organocatalyst: A heterogeneous and green hybrid catalyst for organic transformations. RSC Adv. 2014, 4, 28238–28248. 10.1039/C4RA03773A. [DOI] [Google Scholar]
  28. Kocaman E.; Akarçay Ö.; Bağlar N.; Çelebi S.; Uzun A. Isobutene oligomerization on MCM-41-supported tungstophosphoric acid. Mol. Catal. 2018, 457, 41–50. 10.1016/j.mcat.2018.07.013. [DOI] [Google Scholar]
  29. Dekamin M. G.; Arefi E.; Yaghoubi A. Isocyanurate-based periodic mesoporous organosilica (PMO-ICS): a highly efficient and recoverable nanocatalyst for the one-pot synthesis of substituted imidazoles and benzimidazoles. RSC Adv. 2016, 6, 86982–86988. 10.1039/C6RA14550G. [DOI] [Google Scholar]
  30. Tamoradi T.; Ghadermazi M.; Ghorbani-Choghamarani A. Synthesis of polyhydroquinoline, 2, 3-dihydroquinazolin-4 (1H)-one, sulfide and sulfoxide derivatives catalyzed by new copper complex supported on MCM-41. Catal. Lett. 2018, 148, 857–872. 10.1007/s10562-018-2311-x. [DOI] [Google Scholar]
  31. Kumar N.; Konova P. M.; Naydenov A.; Heikillä T.; Salmi T.; Murzin D. Y. Synthesis of novel Ag modified MCM-41 mesoporous molecular sieve and beta zeolite catalysts for ozone decomposition at ambient temperature. Catal. Lett. 2004, 98, 57–60. 10.1007/s10562-004-6449-3. [DOI] [Google Scholar]
  32. Narkhede N.; Uttam B.; Kandi R.; Rao C. P. Silica–calix hybrid composite of allyl calix [4] arene covalently linked to MCM-41 nanoparticles for sustained release of doxorubicin into cancer cells. ACS omega 2018, 3, 229–239. 10.1021/acsomega.7b01852. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Qi R.; Lin X.; Dai J.; Zhao H.; Liu S.; Fei T.; Zhang T. Humidity sensors based on MCM-41/polypyrrole hybrid film via in-situ polymerization. Sens. Actuators, B 2018, 277, 584–590. 10.1016/j.snb.2018.09.062. [DOI] [Google Scholar]
  34. Da’na E. Adsorption of heavy metals on functionalized-mesoporous silica: A review. Microporous Mesoporous Mater. 2017, 247, 145–157. 10.1016/j.micromeso.2017.03.050. [DOI] [Google Scholar]
  35. Huang W.; Zhang Y.; Li D. Adsorptive removal of phosphate from water using mesoporous materials: A review. J. Environ. Manage. 2017, 193, 470–482. 10.1016/j.jenvman.2017.02.030. [DOI] [PubMed] [Google Scholar]
  36. Ge S.; Geng W.; He X.; Zhao J.; Zhou B.; Duan L.; Wu Y.; Zhang Q. Effect of framework structure, pore size and surface modification on the adsorption performance of methylene blue and Cu2+ in mesoporous silica. Colloid Surf., A 2018, 539, 154–162. 10.1016/j.colsurfa.2017.12.016. [DOI] [Google Scholar]
  37. Brezoiu A.-M.; Deaconu M.; Nicu I.; Vasile E.; Mitran R.-A.; Matei C.; Berger D. Heteroatom modified MCM-41-silica carriers for Lomefloxacin delivery systems. Microporous Mesoporous Mater. 2019, 275, 214–222. 10.1016/j.micromeso.2018.08.031. [DOI] [Google Scholar]
  38. Omar H.; Moosa B.; Alamoudi K.; Anjum D. H.; Emwas A.-H.; El Tall O.; Vu B.; Tamanoi F.; AlMalik A.; Khashab N. M. Impact of Pore–Walls Ligand Assembly on the Biodegradation of Mesoporous Organosilica Nanoparticles for Controlled Drug Delivery. ACS Omega 2018, 3, 5195–5201. 10.1021/acsomega.8b00418. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Koh M. K.; Wong Y. J.; Chai S. P.; Mohamed A. R. Carbon dioxide hydrogenation to methanol over multi-functional catalyst: Effects of reactants adsorption and metal-oxide(s) interfacial area. J. Ind. Eng. Chem. 2018, 62, 156–165. 10.1016/j.jiec.2017.12.053. [DOI] [Google Scholar]
  40. Zhang L.; Li Y.; Zhou H. Preparation and characterization of DBU-loaded MCM-41 for adsorption of CO2. Energy 2018, 149, 414–423. 10.1016/j.energy.2018.02.060. [DOI] [Google Scholar]
  41. Corma A.; Garcia H. Silica-Bound Homogenous Catalysts as Recoverable and Reusable Catalysts in Organic Synthesis. Adv. Synth. Catal. 2006, 348, 1391–1412. 10.1002/adsc.200606192. [DOI] [Google Scholar]
  42. Nowicki J.; Jaroszewska K.; Nowakowska-Bogdan E.; Szmatoła M.; Iłowska J. Synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) over selected organosulfonic acid silica catalysts: Selectivity aspects. Mol. Catal. 2018, 454, 94–103. 10.1016/j.mcat.2018.05.016. [DOI] [Google Scholar]
  43. Kuboňová L.; Peikertová P.; Mamulová Kutláková K.; Jirátová K.; Słowik G.; Obalová L.; Cool P. Catalytic activity of cobalt grafted on ordered mesoporous silica materials in N2O decomposition and CO oxidation. Mol. Catal. 2017, 437, 57–72. 10.1016/j.mcat.2017.04.037. [DOI] [Google Scholar]
  44. Sun Z.; Cui G.; Li H.; Tian Y.; Yan S. Multifunctional dendritic mesoporous silica nanospheres loaded with silver nanoparticles as a highly active and recyclable heterogeneous catalyst. Colloid Surf., A 2016, 489, 142–153. 10.1016/j.colsurfa.2015.10.052. [DOI] [Google Scholar]
  45. Dekamin M. G.; Mokhtari Z. Highly efficient and convenient Strecker reaction of carbonyl compounds and amines with TMSCN catalyzed by MCM-41 anchored sulfonic acid as a recoverable catalyst. Tetrahedron 2012, 68, 922–930. 10.1016/j.tet.2011.10.087. [DOI] [Google Scholar]
  46. Yaghoubi A.; Dekamin M. G.; Karimi B. Propylsulfonic Acid-Anchored Isocyanurate-Based Periodic Mesoporous Organosilica (PMO-ICS-PrSO3H): A Highly Efficient and Recoverable Nanoporous Catalyst for the One-Pot Synthesis of Substituted Polyhydroquinolines. Catal. Lett. 2017, 147, 2656–2663. 10.1007/s10562-017-2159-5. [DOI] [PubMed] [Google Scholar]
  47. Macquarrie D. J.; Maggi R.; Mazzacani A.; Sartori G.; Sartorio R. Understanding the influence of the immobilization procedure on the catalytic activity of aminopropylsilicas in C–C forming reactions. Appl. Catal., A 2003, 246, 183–188. 10.1016/S0926-860X(03)00004-8. [DOI] [Google Scholar]
  48. Rojas-Buzo S.; García-García P.; Corma A. Zr-MOF-808@ MCM-41 catalyzed phosgene-free synthesis of polyurethane precursors. Catal. Sci. Technol. 2019, 9, 146–156. 10.1039/C8CY02235F. [DOI] [Google Scholar]
  49. Eslami M.; Dekamin M. G.; Motlagh L.; Maleki A. MCM-41 mesoporous silica: a highly efficient and recoverable catalyst for rapid synthesis of α-aminonitriles and imines. Green Chem. Lett. Rev. 2018, 11, 36–46. 10.1080/17518253.2017.1421269. [DOI] [Google Scholar]
  50. Wang Z.; Ling H.; Shi J.; Stampfl C.; Yu A.; Hunger M.; Huang J. Acidity enhanced [Al] MCM-41 via ultrasonic irradiation for the Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. J. Catal. 2018, 358, 71–79. 10.1016/j.jcat.2017.11.013. [DOI] [Google Scholar]
  51. Ferré M.; Pleixats R.; Man M. W. C.; Cattoën X. Recyclable organocatalysts based on hybrid silicas. Green Chem. 2016, 18, 881–922. 10.1039/C5GC02579F. [DOI] [Google Scholar]
  52. Wagh K. V.; Gajengi A. L.; Rath D.; Parida K.; Bhanage B. M. Sulphated Al-MCM-41: A simple, efficient and recyclable catalyst for synthesis of substituted aryl ketones/olefins via alcohols addition to alkynes and coupling with styrenes. Mol. Catal. 2018, 452, 46–53. 10.1016/j.mcat.2018.03.023. [DOI] [Google Scholar]
  53. Dekamin M. G.; Peyman S. Z.; Karimi Z.; Javanshir S.; Naimi-Jamal M. R.; Barikani M. Sodium alginate: An efficient biopolymeric catalyst for green synthesis of 2-amino-4H-pyran derivatives. Int. J. Biol. Macromol. 2016, 87, 172–179. 10.1016/j.ijbiomac.2016.01.080. [DOI] [PubMed] [Google Scholar]
  54. Ganem B. Strategies for Innovation in Multicomponent Reaction Design. Acc. Chem. Res. 2009, 42, 463–472. 10.1021/ar800214s. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Cioc R. C.; Ruijter E.; Orru R. V. A. Multicomponent reactions: advanced tools for sustainable organic synthesis. Green Chem. 2014, 16, 2958–2975. 10.1039/C4GC00013G. [DOI] [Google Scholar]
  56. Shi X. L.; Chen Y.; Hu Q.; Zhang W.; Luo C.; Duan P. A potential industrialized fiber-supported copper catalyst for one-pot multicomponent CuAAC reactions in water. J. Ind. Eng. Chem. 2017, 53, 134–142. 10.1016/j.jiec.2017.04.014. [DOI] [Google Scholar]
  57. Palermo V.; Sathicq ÁG.; Constantieux T.; Rodríguez J.; Vázquez P. G.; Romanelli G. P. First Report About the Use of Micellar Keggin Heteropolyacids as Catalysts in the Green Multicomponent Synthesis of Nifedipine Derivatives. Catal. Lett. 2016, 146, 1634–1647. 10.1007/s10562-016-1784-8. [DOI] [Google Scholar]
  58. Dekamin M. G.; Eslami M.; Maleki A. Potassium phthalimide-N-oxyl: a novel, efficient, and simple organocatalyst for the one-pot three-component synthesis of various 2-amino-4H-chromene derivatives in water. Tetrahedron 2013, 69, 1074–1085. 10.1016/j.tet.2012.11.068. [DOI] [Google Scholar]
  59. Shi X. L.; Chen Y.; Hu Q.; Wang F.; Duan P. An efficient, recyclable and large-scalable fiber-supported Fe(III) catalytic system on a simple fixed-bed reactor verified in the Biginelli reactions. J. Ind. Eng. Chem. 2018, 60, 333–340. 10.1016/j.jiec.2017.11.019. [DOI] [Google Scholar]
  60. Kumari M.; Jain Y.; Yadav P.; Laddha H.; Gupta R. Synthesis of Fe3O4-DOPA-Cu Magnetically Separable Nanocatalyst: A Versatile and Robust Catalyst for an Array of Sustainable Multicomponent Reactions under Microwave Irradiation. Catal. Lett. 2019, 149, 2180–2194. 10.1007/s10562-019-02794-8. [DOI] [Google Scholar]
  61. Aghahosseini H.; Ramazani A.; Ślepokura K.; Lis T. The first protection-free synthesis of magnetic bifunctional l-proline as a highly active and versatile artificial enzyme: Synthesis of imidazole derivatives. J. Colloid Interface Sci. 2018, 511, 222–232. 10.1016/j.jcis.2017.10.020. [DOI] [PubMed] [Google Scholar]
  62. Ghorbani-Choghamarani A.; Mohammadi M.; Tamoradi T.; Ghadermazi M. Covalent immobilization of Co complex on the surface of SBA-15: Green, novel and efficient catalyst for the oxidation of sulfides and synthesis of polyhydroquinoline derivatives in green condition. Polyhedron 2019, 158, 25–35. 10.1016/j.poly.2018.10.054. [DOI] [Google Scholar]
  63. Srividya N.; Ramamurthy P.; Shanmugasundaram P.; Ramakrishnan V. Synthesis, characterization, and electrochemistry of some acridine-1, 8-dione dyes. J. Org. Chem. 1996, 61, 5083–5089. 10.1021/jo9600316. [DOI] [Google Scholar]
  64. Girault S.; Grellier P.; Berecibar A.; Maes L.; Mouray E.; Lemiere P.; Debreu M.-A.; Davioud-Charvet E.; Sergheraert C. Antimalarial, antitrypanosomal, and antileishmanial activities and cytotoxicity of bis (9-amino-6-chloro-2-methoxyacridines): influence of the linker. J. Med. Chem. 2000, 43, 2646–2654. 10.1021/jm990946n. [DOI] [PubMed] [Google Scholar]
  65. Wainwright M. Acridine—a neglected antibacterial chromophore. J. Antimicrob. Chemother. 2001, 47, 1–13. 10.1093/jac/47.1.1. [DOI] [PubMed] [Google Scholar]
  66. Gamage S. A.; Spicer J. A.; Atwell G. J.; Finlay G. J.; Baguley B. C.; Denny W. A. Structure–activity relationships for substituted bis (acridine-4-carboxamides): a new class of anticancer agents. J. Med. Chem. 1999, 42, 2383–2393. 10.1021/jm980687m. [DOI] [PubMed] [Google Scholar]
  67. Xiong H.; Han J.; Wang J.; Lu W.; Wang C.; Chen Y.; Lian F.; Zhang N.; Liu Y.-C.; Zhang C. Discovery of 1, 8-acridinedione derivatives as novel GCN5 inhibitors via high throughput screening. Eur. J. Med. Chem. 2018, 151, 740–751. 10.1016/j.ejmech.2018.02.005. [DOI] [PubMed] [Google Scholar]
  68. Iqbal N.; Ali S. A.; Munir I.; Khan S.; Ayub K.; al-Rashida M.; Islam M.; Shafiq Z.; Ludwig R.; Hameed A. Acridinedione as selective flouride ion chemosensor: a detailed spectroscopic and quantum mechanical investigation. RSC Adv. 2018, 8, 1993–2003. 10.1039/C7RA11974G. [DOI] [PMC free article] [PubMed] [Google Scholar]
  69. Indirapriyadharshini V. K.; Karunanithi P.; Ramamurthy P. Inclusion of Resorcinol-Based Acridinedione Dyes in Cyclodextrins: Fluorescence Enhancement. Langmuir 2001, 17, 4056–4060. 10.1021/la0101200. [DOI] [Google Scholar]
  70. Borhade A. V.; Uphade B. K.; Gadhave A. G. Efficient, solvent-free synthesis of acridinediones catalyzed by CdO nanoparticles. Res. Chem. Intermediat. 2015, 41, 1447–1458. 10.1007/s11164-013-1284-z. [DOI] [Google Scholar]
  71. Mahesh P.; Guruswamy K.; Diwakar B. S.; Devi B. R.; Murthy Y. L. N.; Kollu P.; Sri Venkata Narayan P. Magnetically Separable Recyclable Nano-ferrite Catalyst for the Synthesis of Acridinediones and Their Derivatives under Solvent-free Conditions. Chem. Lett. 2015, 44, 1386–1388. 10.1246/cl.150503. [DOI] [Google Scholar]
  72. Martín N.; et al. Synthesis and conformational study of acridine derivatives related to 1, 4-dihydropyridines. J. Heterocycl. Chem. 1995, 32, 235–238. 10.1002/jhet.5570320139. [DOI] [Google Scholar]
  73. Sharma D.; Bandna; Reddy C. B.; Kumar S.; Shil A. K.; Guha N. R.; Das P. Microwave assisted solvent and catalyst free method for novel classes of β-enaminoester and acridinedione synthesis. RSC Adv. 2013, 3, 10335–10340. 10.1039/c3ra23484c. [DOI] [Google Scholar]
  74. Tu S. J.; Miao C.-B.; Gao Y.; Feng Y.-J.; Feng J.-C. Microwave-prompted reaction of cinnamonitrile derivatives with 5, 5-dimethyl-1, 3-cyclohexanedione. Chin. J. Chem. Phys. 2002, 20, 703–706. 10.1002/cjoc.20020200716. [DOI] [Google Scholar]
  75. Zarei Z.; Akhlaghinia B. ZnII doped and immobilized on functionalized magnetic hydrotalcite (Fe3O4/HT-SMTU-ZnII): a novel, green and magnetically recyclable bifunctional nanocatalyst for the one-pot multi-component synthesis of acridinediones under solvent-free conditions. New J. Chem. 2017, 41, 15485–15500. 10.1039/C7NJ03281A. [DOI] [Google Scholar]
  76. Pamuk H.; Aday B.; Şen F.; Kaya M. Pt NPs@GO as a highly efficient and reusable catalyst for one-pot synthesis of acridinedione derivatives. RSC Adv. 2015, 5, 49295–49300. 10.1039/C5RA06441D. [DOI] [PMC free article] [PubMed] [Google Scholar]
  77. Ulus R.; Yıldız Y.; Eriş S.; Aday B.; Şen F.; Kaya M. Functionalized Multi-Walled Carbon Nanotubes (f-MWCNT) as Highly Efficient and Reusable Heterogeneous Catalysts for the Synthesis of Acridinedione Derivatives. ChemistrySelect 2016, 1, 3861–3865. 10.1002/slct.201600719. [DOI] [Google Scholar]
  78. Amoozadeh A.; Golian S.; Rahmani S. TiO2-coated magnetite nanoparticle-supported sulfonic acid as a new, efficient, magnetically separable and reusable heterogeneous solid acid catalyst for multicomponent reactions. RSC Adv. 2015, 5, 45974–45982. 10.1039/C5RA06515A. [DOI] [Google Scholar]
  79. Zolfigol M. A.; Karimi F.; Yarie M.; Torabi M. Catalytic application of sulfonic acid-functionalized titana-coated magnetic nanoparticles for the preparation of 1,8-dioxodecahydroacridines and 2,4,6-triarylpyridines via anomeric-based oxidation. Appl. Organomet. Chem. 2018, 32, e4063 10.1002/aoc.4063. [DOI] [Google Scholar]
  80. Safaei H. R.; Safaei M.; Shekouhy M. Sulfuric acid-modified poly (vinylpyrrolidone)((PVP–SO3H) HSO4): a new highly efficient, bio-degradable and reusable polymeric catalyst for the synthesis of acridinedione derivatives. RSC Adv. 2015, 5, 6797–6806. 10.1039/C4RA12219D. [DOI] [Google Scholar]
  81. Kumar P. S. V.; Suresh L.; Vinodkumar T.; Chandramouli G. Eu2O3 modified CeO2 nanoparticles as a heterogeneous catalyst for an efficient green multicomponent synthesis of novel phenyldiazenyl-acridinedione-carboxylic acid derivatives in aqueous medium. RSC Adv. 2016, 6, 91133–91140. 10.1039/C6RA17990H. [DOI] [Google Scholar]
  82. Işık A.; Aday B.; Ulus R.; Kaya M. One-Pot, Facile, Highly Efficient, and Green Synthesis of Acridinedione Derivatives Using Vitamin B1. Synth. Commun. 2015, 45, 2823–2831. 10.1080/00397911.2015.1109127. [DOI] [Google Scholar]
  83. Bhosle M. R.; Nipte D.; Gaikwad J.; Shaikh M. A.; Bondle G. M.; Sangshetti J. N. A rapid and green method for expedient multicomponent synthesis of N-substituted decahydroacridine-1, 8-diones as potential antimicrobial agents. Res. Chem. Intermed. 2018, 44, 7047–7064. 10.1007/s11164-018-3541-7. [DOI] [Google Scholar]
  84. Valiey E.; Dekamin M. G.; Alirezvani Z. Melamine-modified chitosan materials: An efficient and recyclable bifunctional organocatalyst for green synthesis of densely functionalized bioactive dihydropyrano [2, 3-c] pyrazole and benzylpyrazolyl coumarin derivatives. Int. J. Biol. Macromol. 2019, 129, 407–421. 10.1016/j.ijbiomac.2019.01.027. [DOI] [PubMed] [Google Scholar]
  85. Alirezvani Z.; Dekamin M. G.; Davoodi F.; Valiey E. Melamine-Functionalized Chitosan: A New Bio-Based Reusable Bifunctional Organocatalyst for the Synthesis of Cyanocinnamonitrile Intermediates and Densely Functionalized Nicotinonitrile Derivatives. ChemistrySelect 2018, 3, 10450–10463. 10.1002/slct.201802010. [DOI] [Google Scholar]
  86. Dekamin M. G.; Mehdipoor F.; Yaghoubi A. 1, 3, 5-Tris (2-hydroxyethyl) isocyanurate functionalized graphene oxide: a novel and efficient nanocatalyst for the one-pot synthesis of 3, 4-dihydropyrimidin-2 (1 H)-ones. New J. Chem. 2017, 41, 6893–6901. 10.1039/C7NJ00632B. [DOI] [Google Scholar]
  87. Ishani M.; Dekamin M. G.; Alirezvani Z. Superparamagnetic silica core-shell hybrid attached to graphene oxide as a promising recoverable catalyst for expeditious synthesis of TMS-protected cyanohydrins. J. Colloid Interface Sci. 2018, 521, 232–241. 10.1016/j.jcis.2018.02.060. [DOI] [PubMed] [Google Scholar]
  88. Dekamin M. G.; Ilkhanizadeh S.; Latifidoost Z.; Daemi H.; Karimi Z.; Barikani M. Alginic acid: a highly efficient renewable and heterogeneous biopolymeric catalyst for one-pot synthesis of the Hantzsch 1,4-dihydropyridines. RSC Adv. 2014, 4, 56658–56664. 10.1039/C4RA11801D. [DOI] [Google Scholar]
  89. Hasanzadeh Banakar S.; Dekamin M. G.; Yaghoubi A. Selective and highly efficient synthesis of xanthenedione or tetraketone derivatives catalyzed by ZnO nanorod-decorated graphene oxide. New J. Chem. 2018, 42, 14246–14262. 10.1039/C8NJ01053F. [DOI] [Google Scholar]
  90. Zholobenko V.; Holmes S.; Cundy C.; Dwyer J. Synthesis of MCM-41 materials: an in situ FTIR study. Microporous Mater. 1997, 11, 83–86. 10.1016/S0927-6513(97)00033-3. [DOI] [Google Scholar]
  91. Schacht S.; Janicke M.; Schüth F. Modeling X-ray patterns and TEM images of MCM-41. Microporous Mesoporous Mater. 1998, 22, 485–493. 10.1016/S1387-1811(98)00086-9. [DOI] [Google Scholar]
  92. Mello M. R.; Phanon D.; Silveira G. Q.; Llewellyn P. L.; Ronconi C. M. Amine-modified MCM-41 mesoporous silica for carbon dioxide capture. Microporous Mesoporous Mater. 2011, 143, 174–179. 10.1016/j.micromeso.2011.02.022. [DOI] [Google Scholar]
  93. Dekamin M. G.; Moghaddam F. M.; Saeidian H.; Mallakpour S. The Performance of Phthalimide-N-oxyl Anion. Monatsh. Chem. 2006, 137, 1591–1595. 10.1007/s00706-006-0553-6. [DOI] [Google Scholar]
  94. Moghaddam F. M.; Dekamin M. G.; Koozehgari G. R. A simple and efficient method for synthesis of isocyanurates catalyzed by potassium phthalimide under solvent-free conditions. Lett. Org. Chem. 2005, 2, 734–738. 10.2174/157017805774717508. [DOI] [Google Scholar]
  95. Nhavene E. P. F.; Andrade G. F.; Faria J. A. Q. A.; Gomes D. A.; Sousa E. M. B. d. Biodegradable Polymers Grafted onto Multifunctional Mesoporous Silica Nanoparticles for Gene Delivery. ChemEngineering 2018, 2, 24 10.3390/chemengineering2020024. [DOI] [Google Scholar]
  96. ALOthman Z. A. A review: fundamental aspects of silicate mesoporous materials. Materials 2012, 5, 2874–2902. 10.3390/ma5122874. [DOI] [Google Scholar]
  97. Alinezhad H.; Tajbakhsh M.; Norouzi M.; Baghery S.; Rakhtshah J. Green and expeditious synthesis of 1, 8-dioxodecahydroacridine derivatives catalysed by protic pyridinium ionic liquid. J. Chem. Sci. 2013, 125, 1517–1522. 10.1007/s12039-013-0517-4. [DOI] [Google Scholar]
  98. Zhu A.; Liu R.; Du C.; Li L. Betainium-based ionic liquids catalyzed multicomponent Hantzsch reactions for the efficient synthesis of acridinediones. RSC Adv. 2017, 7, 6679–6684. 10.1039/C6RA25709G. [DOI] [Google Scholar]
  99. Yü S. J.; Wu S.; Zhao X. M.; Lü C.-W. Green and efficient synthesis of acridine-1, 8-diones and hexahydroquinolines via a KH2PO4 catalyzed Hantzsch-type reaction in aqueous ethanol. Res. Chem. Intermed. 2017, 43, 3121–3130. 10.1007/s11164-016-2814-2. [DOI] [Google Scholar]
  100. Fan X.; Li Y.; Zhang X.; Qu G.; Wang J. An efficient and green preparation of 9-arylacridine-1, 8-dione derivatives. Heteroatom Chem. 2007, 18, 786–790. 10.1002/hc.20410. [DOI] [Google Scholar]
  101. Ziarani G. M.; Badiei A.; Hassanzadeh M.; Mousavi S. Synthesis of 1, 8-dioxo-decahydroacridine derivatives using sulfonic acid functionalized silica (SiO2-Pr-SO3H) under solvent free conditions. Arab. J. Chem. 2014, 7, 335–339. 10.1016/j.arabjc.2011.01.037. [DOI] [Google Scholar]
  102. Wang G. W.; Xia J. J.; Miao C. B.; Wu X. L. Environmentally friendly and efficient synthesis of various 1, 4-dihydropyridines in pure water. Bull. Chem. Soc. Jpn. 2006, 79, 454–459. 10.1246/bcsj.79.454. [DOI] [Google Scholar]
  103. Patil D.; Chandam D.; Mulik A.; Patil P.; Jagadale S.; Kant R.; Gupta V.; Deshmukh M. Novel Brønsted Acidic Ionic Liquid ([CMIM][CF3COO]) Prompted Multicomponent Hantzsch Reaction for the Eco-Friendly Synthesis of Acridinediones: An Efficient and Recyclable Catalyst. Catal. Lett. 2014, 144, 949–958. 10.1007/s10562-014-1202-z. [DOI] [Google Scholar]
  104. Steinrück H.-P.; Wasserscheid P. Ionic liquids in catalysis. Catal. Lett. 2015, 145, 380–397. 10.1007/s10562-014-1435-x. [DOI] [Google Scholar]
  105. Jin T. S.; Zhang J. S.; Guo T. T.; Wang A. Q.; Li T. S. One-pot clean synthesis of 1, 8-dioxo-decahydroacridines catalyzed by p-dodecylbenezenesulfonic acid in aqueous media. Synthesis 2004, 2004, 2001–2005. 10.1055/s-2004-829151. [DOI] [Google Scholar]
  106. Tang Z. Q.; Chen Y.; Liu C. N.; Cai K. Y.; Tu S. J. A green procedure for the synthesis of 1, 8-dioxodecahydroacridine derivatives under microwave irradiation in aqueous media without catalyst. J. Heterocycl. Chem. 2010, 47, 363–367. 10.1002/jhet.322. [DOI] [Google Scholar]
  107. Walvoord R. R.; Huynh P. N. H.; Kozlowski M. C. Quantification of Electrophilic Activation by Hydrogen-Bonding Organocatalysts. J. Am. Chem. Soc. 2014, 136, 16055–16065. 10.1021/ja5086244. [DOI] [PMC free article] [PubMed] [Google Scholar]
  108. Tran N. T.; Min T.; Franz A. K. Silanediol Hydrogen Bonding Activation of Carbonyl Compounds. Chem. - Eur. J. 2011, 17, 9897–9900. 10.1002/chem.201101492. [DOI] [PubMed] [Google Scholar]
  109. Tan B.; Hernández-Torres G.; Barbas C. F. Highly Efficient Hydrogen-Bonding Catalysis of the Diels–Alder Reaction of 3-Vinylindoles and Methyleneindolinones Provides Carbazolespirooxindole Skeletons. J. Am. Chem. Soc. 2011, 133, 12354–12357. 10.1021/ja203812h. [DOI] [PubMed] [Google Scholar]
  110. Valiey E.; Dekamin M. G.; Alirezvani Z. Melamine-modified chitosan materials: An efficient and recyclable bifunctional organocatalyst for green synthesis of densely functionalized bioactive dihydropyrano[2,3-c]pyrazole and benzylpyrazolyl coumarin derivatives. Int. J. Biol. Macromol. 2019, 129, 407–421. 10.1016/j.ijbiomac.2019.01.027. [DOI] [PubMed] [Google Scholar]
  111. Dekamin M. G.; Azimoshan M.; Ramezani L. Chitosan: a highly efficient renewable and recoverable bio-polymer catalyst for the expeditious synthesis of [small alpha]-amino nitriles and imines under mild conditions. Green Chem. 2013, 15, 811–820. 10.1039/c3gc36901c. [DOI] [Google Scholar]
  112. Roca-Lopez D.; Sadaba D.; Delso I.; Herrera R. P.; Tejero T.; Merino P. Asymmetric organocatalytic synthesis of γ-nitrocarbonyl compounds through Michael and Domino reactions. Tetrahedron: Asymmetry 2010, 21, 2561–2601. 10.1016/j.tetasy.2010.11.001. [DOI] [Google Scholar]
  113. Madankumar N.; Pitchumani K. β-Cyclodextrin Monosulphonic Acid Promoted Multicomponent Synthesis of 1, 8-Dioxodecahydroacridines in Water. ChemistrySelect 2018, 3, 10886–10891. 10.1002/slct.201802244. [DOI] [Google Scholar]
  114. Sehout I.; Boulcina R.; Boumoud B.; Boumoud T.; Debache A. Solvent-free synthesis of polyhydroquinoline and 1, 8-dioxodecahydroacridine derivatives through the Hantzsch reaction catalyzed by a natural organic acid: A green method. Synth. Commun. 2017, 47, 1185–1191. 10.1080/00397911.2017.1316406. [DOI] [Google Scholar]
  115. Shi D. Q.; Ni S. N.; Shi J. W.; Dou G. L.; Li X. Y.; Wang X. S. An efficient synthesis of polyhydroacridine derivatives by the three-component reaction of aldehydes, amines and dimedone in ionic liquid. J. Heterocycl. Chem. 2008, 45, 653–660. 10.1002/jhet.5570450303. [DOI] [Google Scholar]
  116. Davoodnia A.; Khojastehnezhad A.; Tavakoli-Hoseini N. Carbon-based solid acid as an efficient and reusable catalyst for the synthesis of 1, 8-dioxodecahydroacridines under solvent-free conditions. Bull. Korean Chem. Soc. 2011, 32, 2243–2248. 10.5012/bkcs.2011.32.7.2243. [DOI] [Google Scholar]
  117. Hong M.; Xiao G. FSG-Hf (NPf2) 4 catalyzed, environmentally benign synthesis of 1, 8-dioxo-decahydroaridines in water–ethanol. J. Fluorine Chem. 2012, 144, 7–9. 10.1016/j.jfluchem.2012.09.006. [DOI] [Google Scholar]
  118. Mokhtary M.; Langroudi S. A. M. Polyvinylpolypyrrolidone-supported boron trifluoride: a mild and efficient catalyst for the synthesis of 1, 8-dioxooctahydroxanthenes and 1, 8-dioxodecahydroacridines. Monatsh. Chem. 2014, 145, 1489–1494. 10.1007/s00706-014-1206-9. [DOI] [Google Scholar]

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