Preparation method and application of alpha-diimine palladium functionalized conjugated organic porous material

Abstract

The present application relates to the technical field of organic functional materials, and particularly relates to a preparation method of alpha-diimine palladium functionalized conjugated organic porous material and application thereof.The alpha-diimine palladium functionalized conjugated organic porous material is prepared by using alpha-diimine palladium functionalized monomer and polyacetylenyl benzene monomer as raw materials, and through one-step coupling reaction under the action of a catalyst to obtain a conjugated organic porous material with catalytic activity.Compared with a traditional palladium catalyst, the alpha-diimine palladium is uniformly distributed in the material skeleton, the loading amount of palladium is high, and the shortcomings such as easy aggregation of palladium in the traditional method are avoided;in addition, the preparation method is very simple, and the yield is high, and is suitable for industrial production.The alpha-diimine palladium functionalized conjugated organic porous material prepared by the present application is used for catalyzing direct C-H arylation reaction of aryl bromide and heteroaromatic compound, and has good catalytic activity and catalytic cycle stability, and is easy to recover.

Description

Technical Field

[0001] This invention relates to the field of organic functional materials technology, and in particular to a method for preparing α-diimine palladium-functionalized conjugated organic porous materials and their applications. Background Technology

[0002] The statements in this section merely refer to the background art related to this invention and do not necessarily constitute prior art.

[0003] Aryl heterocyclic compounds are important components of natural products, pharmaceuticals, bioactive molecules, and polymer materials. In recent years, researchers have focused on developing various synthetic methods to construct aryl heterocyclic compounds. Among these, palladium-catalyzed direct CH arylation is a direct and atom-economical method for constructing these compounds, avoiding the use of expensive organometallic reagents and the generation of salt waste in traditional palladium-catalyzed cross-coupling reactions. However, due to the inert nature of the C-H bond, its dissociation requires high temperatures and high palladium loading. Exploring efficient pre-catalysts can significantly improve catalytic activity, achieving low palladium loading and mild reaction conditions.

[0004] In these studies, α-diimine ligands exhibited unique advantages: ①N(sp 2 The strong σ-donor properties of N(sp) promote the oxidative addition of halogenated aromatics; ②N(sp) 2 The bidentate coordination of the ligand ensures strong chelation with the Pd-N bond; ③ The hindrance of the N-aryl moiety and ligand skeleton facilitates the reductive elimination process. It is noteworthy that the hindrance of the N-aryl moiety and skeleton in the ligand structure is essential for improving efficiency and selectivity, as they effectively protect palladium in the presence of crowded spaces. In contrast, less hindrance ligands generally lead to lower yields, which may be attributed to the presence of N-aryl moiety in the Nd-N bond. Ar Rapid decomposition of palladium when rotational protection is lost.

[0005] Despite the significant progress made in the palladium catalytic conversion mentioned above, there are still problems such as the difficulty in obtaining large-volume three-dimensional palladium complexes and the difficulty in recovering homogeneous catalysts. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a conjugated organic porous material that is easy to prepare and has a large volume of α-diimine palladium functionalized, which serves as a heterogeneous catalyst for the direct CH arylation reaction of aryl bromides and heteroaryl hydrocarbons, is easy to recover, and has good catalytic activity and catalytic cycle stability.

[0007] In a first aspect, the present invention provides a method for preparing α-diimine palladium-functionalized conjugated organic porous materials. The method uses α-diimine palladium-functionalized monomers and polyacetylenoid monomers as raw materials, and carries out a coupling reaction under the action of a catalyst to obtain α-diimine palladium-functionalized conjugated organic porous materials.

[0008] The structural formula of the α-diimine palladium functionalized monomer is shown below:

[0009]

[0010] R1 is selected from hydrogen, methyl, isopropyl, phenyl, or butyl; R2 is selected from hydrogen, methyl, or phenyl; and Y is selected from chlorine, bromine, or iodine.

[0011] The polyynylbenzene monomer contains multiple ynyl groups and at least one benzene ring structure, and may also include a six-membered ring structure. The polyynylbenzene monomer of the present invention preferably has the following structures:

[0012]

[0013] The reaction equation for the coupling reaction is shown below:

[0014]

[0015] In the coupling reaction, the molar ratio of α-diimine palladium functionalized monomer, polyacetylenoid monomer, and catalyst is 1:0.5-0.75:0.1-0.3.

[0016] The catalyst is a co-catalyst composed of bis(triphenylphosphine)palladium dichloride and cuprous iodide, wherein the molar ratio of bis(triphenylphosphine)palladium dichloride to cuprous iodide is 1:2-4; the coupling reaction is a sonogashira coupling reaction.

[0017] The solvent for the coupling reaction is any one of N,N-dimethylformamide, tetrahydrofuran, dioxane, and toluene mixed with triethylamine.

[0018] The coupling reaction is carried out at a temperature of 60-100℃, preferably 80℃, and for a reaction time of 48-96h, preferably 72h.

[0019] The preparation method of the α-diimine palladium-functionalized conjugated organic porous material further includes the following steps: after the product undergoing the coupling reaction is filtered, washed, Soxhlet extracted, and vacuum dried, the α-diimine palladium-functionalized conjugated organic porous material is obtained.

[0020] Secondly, the present invention provides an α-diimine palladium-functionalized conjugated organic porous material prepared by the above preparation method.

[0021] Thirdly, the present invention provides an application of the above-mentioned α-diimine palladium-functionalized conjugated organic porous material in the catalytic direct CH arylation reaction of aryl bromides and heteroaromatic compounds.

[0022] Furthermore, the specific steps of the direct CH arylation reaction are as follows: under a nitrogen atmosphere, using aryl bromides and heteroaromatic compounds as reaction substrates, adding α-diimine palladium-functionalized conjugated organic porous materials as catalysts, and carrying out the reaction at a predetermined temperature.

[0023] The direct CH arylation reaction uses DMAc as the reaction solvent.

[0024] In the direct CH arylation reaction, a certain amount of potassium carbonate is added as a base, and terpentine is added as an additive.

[0025] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0026] (1) The method for preparing α-diimine palladium-functionalized conjugated organic porous materials provided by the present invention uses α-diimine palladium as a functional monomer and polyacetylenoid monomer as a structural monomer to construct catalytically active conjugated organic porous materials through a one-step coupling reaction. Compared with traditional supported palladium catalysts, the α-diimine palladium in the porous materials of the present invention is uniformly distributed in the material framework and has a high palladium loading, while avoiding the disadvantages of palladium agglomeration in traditional methods; in addition, the traditional homogeneous large-volume α-diimine palladium catalyst synthesis route is cumbersome and has low yield, while the preparation method of the porous materials of the present invention is very simple and has a high yield, making it suitable for industrial production;

[0027] (2) The α-diimine palladium-functionalized conjugated organic porous material prepared in this invention can be used to catalyze the direct CH arylation reaction of aryl bromides and heteroaryl hydrocarbons. Since the prepared material is insoluble in the solvent system of the direct CH arylation reaction, it belongs to heterogeneous catalysis and has good recyclability. At the same time, the α-diimine palladium-functionalized conjugated organic porous material provided by this invention uses a large conjugated material framework as ligand to provide steric hindrance. Considering both electronic effects and steric hindrance effects, this material can provide catalytic effects comparable to homogeneous α-diimine palladium catalysis with large steric hindrance. Attached Figure Description

[0028] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0029] Figure 1 Solid-state nuclear magnetic resonance of the α-diimine palladium-functionalized conjugated organic porous material (DIM-Pd-CMP-1) prepared in Example 1 13 C spectrum;

[0030] Figure 2 The image shows the Pd 3d X-ray photoelectron spectrum of the DIM-Pd-CMP-1 material prepared in Example 1.

[0031] Figure 3 The N1s X-ray photoelectron spectrum of the DIM-Pd-CMP-1 material prepared in Example 1 is shown below.

[0032] Figure 4 Thermogravimetric analysis (TGA) diagram of the DIM-Pd-CMP-1 material prepared in Example 1;

[0033] Figure 5 The powder X-ray diffraction pattern of the DIM-Pd-CMP-1 material prepared in Example 1;

[0034] Figure 6 This is a scanning electron microscope image of the DIM-Pd-CMP-1 material prepared in Example 1;

[0035] Figure 7 The nitrogen adsorption curve of the DIM-Pd-CMP-1 material prepared in Example 1 is shown.

[0036] Figure 8 The image shows the pore size distribution of the DIM-Pd-CMP-1 material prepared in Example 1. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] The abbreviations used in the following examples have the following meanings: DMF represents N,N-dimethylformamide; Et3N represents triethylamine; DMAc represents N,N-dimethylacetamide; 1 H NMR represents hydrogen nuclear magnetic resonance spectrum; 13 CNMR stands for carbon nuclear magnetic resonance spectroscopy; PivOH represents tervastatin; TLC represents thin-layer chromatography; EtOAc represents ethyl acetate. This invention does not impose any special restrictions on the source of the reagents used in the examples; commercially available products well-known to those skilled in the art can be used.

[0039] Example 1: Preparation of α-diimine palladium-functionalized conjugated organic porous material DIM-Pd-CMP-1

[0040] The α-diimine palladium functionalized monomer (1E,2E)-N 1 N 2 Bis(4-bromo-2,6-diisopropyl)ethane-1,2-diimine palladium chloride (426 mg, 0.60 mmol), polyynylbenzene monomer 1,3,5-tris(4-ethynylphenyl)benzene (151 mg, 0.4 mmol), bis(triphenylphosphine)dichloride palladium chloride (50 mg), and copper iodide (25 mg) were added separately to dry round-bottom flasks. Anhydrous DMF (6.0 mL) and Et3N (6.0 mL) were then added to the mixture via syringe. The resulting mixture was heated to 80 °C and stirred under a nitrogen atmosphere for 72 h. After cooling to room temperature, the obtained organic polymer was filtered and washed four times with chloroform, water, methanol, and acetone to remove unreacted monomers or catalyst residues. The polymer was further purified by Soxhlet extraction with methanol for 48 h. The product was dried under vacuum at 70 °C for 6 h to obtain a brown powder, which was named DIM-Pd-CMP-1. The yield was approximately 95%. The specific surface area of ​​DIM-Pd-CMP-1 material is 502 m². 2 / g, with an average pore size of 2.1nm.

[0041]

[0042] Figure 1 Solid-state NMR of DIM-Pd-CMP-1, a conjugated organic porous material functionalized with α-diimine palladium. 13 C-spectrum. Solid-state NMR of DIM-Pd-CMP-1. 13 The C spectrum shows that the peak at approximately 90 ppm is designated as sp-hybridized -C. Ar -C≡CC Ar The presence of -alkynyl signal peaks indicates the successful formation of the -C≡C- functional group. The signals at approximately 161, 146, 136, 126, 121, 28, and 22 ppm can be attributed to carbon atoms of α-diimine palladium, while the signals at approximately 140, 132, 126, and 121 ppm can be attributed to carbon atoms of 1,3,5-tris(ethynylphenyl)benzene. This confirms that the α-diimine palladium functionalized monomer and the poly-alkynylbenzene structural monomer have been successfully embedded in the CMP material framework.

[0043] Figure 2 The image shows the X-ray photoelectron spectrum of Pd 3d in DIM-Pd-CMP-1. The XPS spectrum shows that the binding energy (BE) of the Pd 3d 5 / 2 orbital is 337.55 eV, indicating that the Pd species in DIM-Pd-CMP-1 exists in the +2 valence state.

[0044] Figure 3The image shows the N1s X-ray photoelectron spectrum of DIM-Pd-CMP-1. The binding energy of N1s in DIM-Pd-CMP-1 shifts positively from 398.8 eV to 400.1 eV, further indicating a strong coordination interaction between the N,N-bident ligand and PdCl2.

[0045] Figure 4 The thermogravimetric analysis (TGA) diagram shows that the DIM-Pd-CMP-1 material prepared in Example 1 is stable up to 300°C under a nitrogen atmosphere.

[0046] Figure 5 The image shows the powder X-ray diffraction pattern of the DIM-Pd-CMP-1 material prepared in Example 1. Powder X-ray diffraction (PXRD) indicates that DIM-Pd-CMP-1 has an amorphous structure.

[0047] Figure 6 This is a scanning electron microscope (SEM) image of the DIM-Pd-CMP-1 material prepared in Example 1. The SEM image shows that DIM-Pd-CMP-1 is composed of irregularly packed nanoscale particles, exhibiting a loose structure with numerous mesopores between the packed particles.

[0048] Figure 7 , Figure 8 The figures show the nitrogen adsorption curve and pore size distribution of DIM-Pd-CMP-1, respectively. The specific surface area of ​​Pd-PEPPSI-HCP-1, measured by a specific surface area and pore size analyzer, is 502 m². 2 / g, and its pore size distribution curve shows that there are a large number of micropores and mesopores in the CMP material.

[0049] The palladium content in DIM-Pd-CMP-1 was determined to be 8.51 wt% by ICP-AES.

[0050] Example 2

[0051] The only difference from Example 1 is that the α-diimine palladium functionalized monomer and polyacetylenoid monomer shown in Table 1 are used.

[0052] Table 1. Reactive monomer structures, yields, and specific surface areas of conjugated organic porous materials.

[0053]

[0054]

[0055] The structural formulas of the conjugated organic porous materials shown in Table 2 and Table 1 are as follows:

[0056]

[0057]

[0058]

[0059] Experimental Example 1: Catalytic Experiment of Direct Aromaticization Reaction of Aryl Bromines and Heteroaromatic Compounds (CH)

[0060] This example demonstrates the use of the synthetic products from Examples 1-2 for the direct arylation reaction of aryl bromides and heteroaromatic compounds (CH). The specific steps are as follows:

[0061] In a reaction tube equipped with a magnetic stir bar, 0.5 mol% of α-diimine palladium-functionalized conjugated organic porous material, 0.2 mmol of aryl bromide, 0.3 mmol of heteroaromatic compound, 0.3 mmol of K₂CO₃, 0.06 mmol of PivOH, and 1.0 mL of DMAc were added. The reaction mixture was stirred at 130 °C for 12 h. After the reaction was complete (monitored by TLC), the reaction mixture was cooled to room temperature, centrifuged, and the solid was washed with EtOAc (3 × 5 mL). The combined organic phases were extracted and washed three times with dichloromethane. The organic layer was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (10 / 1, v / v) as the eluent. Table 3 shows the specific catalytic experimental results of the α-diimine palladium-functionalized conjugated organic porous material prepared in the examples of this application.

[0062] The α-diimine palladium-functionalized conjugated organic porous material catalyst was recovered by centrifugation. The recovered catalyst was washed with ethyl acetate and methanol / water to remove residual products, and after simple drying, it was reused for the initial reaction. A total of six cyclic catalytic experiments were conducted, and the yield of the sixth cycle is shown in Table 3. It can be seen that after six cycles, the CH arylation reaction catalyzed by the catalyst still maintains a high yield, indicating that the α-diimine palladium-functionalized conjugated organic porous material prepared in this invention has good catalytic cycle stability.

[0063] Table 3 Catalytic experiments of α-diimine palladium-functionalized conjugated organic porous materials

[0064]

[0065]

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an α-diimine palladium-functionalized conjugated organic porous material, characterized in that, Using α-diimine palladium functionalized monomers and polyynylbenzene monomers as raw materials, a coupling reaction was carried out under the action of a catalyst to obtain α-diimine palladium functionalized conjugated organic porous materials. The structural formula of the α-diimine palladium functionalized monomer is shown below: Where R1 is selected from hydrogen, methyl, isopropyl, phenyl, or butyl; R2 is selected from hydrogen, methyl, or phenyl; and Y is selected from chlorine, bromine, or iodine. The polyacetylenic benzene monomer is selected from any of the following structures: ； The molar ratio of the α-diimine palladium functionalized monomer, the polyacetylenic benzene monomer, and the catalyst is 1:0.5-0.75:0.1-0.3; The catalyst is a co-catalyst composed of palladium dichloride and cuprous iodide, wherein the molar ratio of palladium dichloride to cuprous iodide is 1:2-4.

2. The preparation method according to claim 1, characterized in that, The solvent for the coupling reaction is any one of N,N-dimethylformamide, tetrahydrofuran, dioxane, and toluene mixed with triethylamine.

3. The preparation method according to claim 1, characterized in that, The coupling reaction is carried out at a temperature of 60-100°C. o C; the reaction time is 48h-96h.

4. The preparation method according to claim 3, characterized in that, The reaction temperature of the coupling reaction is 80°C. o C; the reaction time is 72 hours.

5. The preparation method according to claim 1, characterized in that, The preparation method further includes the following steps: after the product undergoing the coupling reaction is filtered, washed, Soxhlet extracted, and vacuum dried, the α-diimine palladium-functionalized conjugated organic porous material is obtained.

6. An α-diimine palladium-functionalized conjugated organic porous material prepared by a method for preparing α-diimine palladium-functionalized conjugated organic porous material as described in claim 1.

7. The application of the α-diimine palladium-functionalized conjugated organic porous material as described in claim 6 in the catalytic direct CH arylation reaction of aryl bromides and heteroaromatic compounds.

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