Supported chiral phosphine heterogeneous catalysts, methods for their preparation and use

Abstract

The application discloses a supported chiral phosphine heterogeneous catalyst and a preparation method and application thereof, and relates to the technical field of heterogeneous catalyst preparation. The method comprises the following steps: mixing hollow mesoporous polystyrene nanospheres, chiral phosphine and DCE, stirring, adding FDA, stirring, adding concentrated sulfuric acid dropwise, and reacting to obtain a reactant one; and mixing the reactant one, toluene, tetramethyldisiloxane and tetraisopropyl titanate, and reacting under temperature rise to obtain the supported chiral phosphine heterogeneous catalyst. The application is simple and convenient in a one-pot method, and can efficiently anchor the chiral phosphine and its oxide catalyst to the carrier. The application solves the problems of complicated modification in the existing organic catalyst immobilization process and mass transfer limitation of the prepared catalyst.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous catalyst preparation technology, specifically to a supported chiral phosphine heterogeneous catalyst, its preparation method, and its application. Background Technology

[0002] Chiral phosphine and chiral phosphine oxides, as Lewis base catalysts, are widely used in asymmetric organocatalytic reactions. However, homogeneous catalysis of chiral Lewis bases faces challenges such as high catalyst cost, air sensitivity leading to easy oxidation, and difficulty in separating the expensive chiral catalyst from the reaction mixture after the reaction, resulting in a cumbersome and energy-intensive process. These drawbacks significantly limit the large-scale use of chiral phosphine and chiral phosphine oxide catalysts. The ideal solution to this problem lies in heterogeneous catalysis. It is well known that chiral organocatalysts can be attached to various supports through non-covalent and covalent fixation. The main advantage of non-covalent fixation via acid-base reactions, ion-pair interactions, hydrogen bonding, and hydrophobic interactions is the direct "one-pot" anchoring without molecular modification. However, non-covalent fixation via weak secondary bonds often leads to the loss of expensive chiral organocatalysts during the catalytic process, greatly hindering large-scale industrial applications. In contrast, covalent fixation is a more efficient fixation method. Currently, various materials, including organic polymers, inorganic materials, MOFs, and COFs, have been developed as supports for anchoring chiral phosphine and chiral phosphine oxide organocatalysts via covalent bonds.

[0003] However, the heterogeneity of chiral phosphine oxide organic catalysts currently faces the following problems: (1) Covalent immobilization of chiral organic catalysts requires multi-step molecular modification to create anchor sites that can be linked to various supports, which is cumbersome and time-consuming; (2) The morphology and porous structure of chiral phosphine oxide catalysts supported by the "bottom-up" method cannot be well controlled, failing to meet the urgent requirements of rapid substrate access to catalytic sites and uniform pore space constraints, resulting in decreased catalytic activity and stereoselectivity; (3) There is a lack of special attention to the oxidation of chiral phosphine, which is easily oxidized to pentavalent phosphorus and loses its activity during the heterogeneity process. Therefore, it is very necessary to develop a simple and efficient anchoring strategy for chiral phosphine and chiral phosphine oxide catalysts, and to construct supported chiral phosphine and chiral phosphine oxide catalysts with good mass transfer performance to meet the requirements of low-cost and high-performance construction of chiral optically active molecules. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a supported chiral phosphine heterogeneous catalyst, its preparation method, and its application, thereby solving the problems of cumbersome modification required for the existing organic catalyst immobilization process and the resulting catalyst having mass transfer limitations.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing a supported chiral phosphine heterogeneous catalyst is provided, comprising the following steps:

[0006] (1) Mix hollow mesoporous polystyrene nanospheres, chiral phosphine and DCE, stir, add FDA, stir again, add concentrated sulfuric acid dropwise, heat to 75-85℃ and react for 0.8-1.2h, cool to room temperature, centrifuge, wash and dry to obtain reactant one;

[0007] (2) The reactants I, toluene, tetramethyldisiloxane and tetraisopropyl titanate obtained in step (1) are mixed, heated to 65-75℃ and reacted for 28-32h, cooled to room temperature, centrifuged, washed and dried to obtain the supported chiral phosphine heterogeneous catalyst.

[0008] The beneficial effects of this invention are as follows:

[0009] 1. One-pot direct anchoring of chiral phosphine

[0010] To address the challenges of constructing anchor points for chiral phosphine catalysts and the cumbersome anchoring process, this invention employs the FC reaction, using FDA as a crosslinking agent, to establish covalent bonds between the aromatic rings of organophosphine and the benzene rings of hollow mesoporous polystyrene nanospheres. This eliminates the need for tedious steps in preparing anchor points on small molecule catalysts, enabling efficient and convenient anchoring of expensive chiral phosphine organocatalysts.

[0011] 2. Breakthrough in mass transfer limitations

[0012] According to the heterogeneous catalytic reaction mechanism, reactants must first overcome the resistance between the fluid and solid phases to reach or adsorb onto the surface of a solid catalyst, and then overcome the internal resistance of the catalyst to diffuse into the macropores, mesopores, or even micropores within the catalyst. This is the physical transport process of interphase diffusion and intracellular diffusion within nanospheres. To overcome the influence of these mass transfer resistances on heterogeneous catalytic reactions, the specific surface area and pore structure of the support need to be designed. To obtain the maximum reactivity per unit volume or unit mass, most supports are made porous to increase their surface area. Taking the reaction kinetics in porous spheres as an example, for first-order kinetics, under constant surface concentration, an effective factor (η) for the effect of pore diffusion on the reaction rate is introduced as a function of Thiele's spherical particle:

[0013]

[0014]

[0015] Where, φ s K1 is the Thiele modulus of the sphere, and K1 is the first-order kinetic constant (s). -1 R is the radius of the sphere (cm), and D is the radius of the sphere. e Effective diffusion coefficient (cm)2 ·s -1 From formulas (1) and (2), it can be seen that the effective diffusion coefficient (D) e The larger the sphere radius (R), the smaller the effective diffusion factor (η). Based on Fick's law, the effective diffusion coefficient (D) is... e The diffusion coefficient (D) is influenced by pore geometry, including porosity (θ) and curvature factor (τ). Addressing the issue of large organophosphorus molecules and the high requirements for the pore structure of the support, we selected hollow mesoporous polystyrene nanospheres as the support. The hollow structure of the catalyst support can provide a large concentration gradient for heterogeneous reactions, resulting in a lower diffusion coefficient (D). e By utilizing the excellent pore structure and swelling properties of hollow mesoporous polystyrene nanospheres, the mass transfer problem in catalytic reactions can be solved, thereby improving the catalytic efficiency of the catalyst.

[0016] 3. Control of chiral phosphine oxidation

[0017] To address the oxidation problem in the loading and catalytic reaction of chiral phosphine, this invention uses tetramethyldisiloxane (TMDS) as a reducing agent and tetraisopropyl titanate (Ti(OiPr)4) as a catalyst to reduce and repair heterogeneous catalysts. Through chemical reduction, pentavalent phosphorus is reduced to trivalent phosphorus, reactivating the deactivated catalytic sites and further improving the service life of heterogeneous catalysts.

[0018] Based on the above technical solution, the present invention can be further improved as follows:

[0019] Furthermore, in step (1), hollow mesoporous polystyrene nanospheres, chiral phosphine, and DCE are mixed under Ar protection.

[0020] Furthermore, in step (1), the molar ratio of hollow mesoporous polystyrene nanospheres to chiral phosphine is 90-110 mg: 0.1-0.3 mmol.

[0021] Furthermore, in step (1), the molar ratio of hollow mesoporous polystyrene nanospheres to chiral phosphine is 100 mg: 0.2 mmol.

[0022] Furthermore, in step (1), the molar volume ratio of chiral phosphine, FDA, DCE and concentrated sulfuric acid is 0.1-0.3 mmol: 3-5 mmol: 18-22 mL: 1-2 mL.

[0023] Furthermore, in step (1), the molar volume ratio of chiral phosphine, FDA, DCE and concentrated sulfuric acid is 0.2 mmol: 4 mmol: 20 mL: 1.5 mL.

[0024] Furthermore, in step (1), the mixture is stirred at room temperature for 1.5-2.5 hours.

[0025] Furthermore, in step (1), the mixture is stirred for 8-12 minutes.

[0026] Furthermore, in step (1), the concentration of concentrated sulfuric acid is 98 wt%.

[0027] Furthermore, in step (1), concentrated sulfuric acid is replaced with FeCl3.

[0028] Furthermore, in step (1), the washing solution is washed sequentially with deionized water and anhydrous ethanol until it is neutral.

[0029] Furthermore, in step (1), the chiral phosphine is

[0030] Furthermore, in step (1), the hollow mesoporous polystyrene nanospheres are prepared by the following method:

[0031] S1: Dissolve styrene and divinylbenzene in anhydrous ethanol to obtain reaction solution one;

[0032] S2: Mix ethanol, water, polyvinylpyrrolidone and poloxamer, stir until dissolved, add styrene, continue stirring, add KPS solution, heat to 70-80℃ and react for 1.8-2.2h, add reaction solution one obtained in step S1 dropwise, react at 70-80℃ for 20-25h, cool to room temperature, centrifuge and wash to obtain a white solid;

[0033] S3: The white solid obtained in step S2 is dispersed in THF and stirred at room temperature for 5-7 hours. After centrifugation, it is further dispersed in acetone and stirred at 60-70℃ for 10-15 hours. After centrifugation, washing and drying, hollow mesoporous polystyrene nanospheres are obtained.

[0034] Furthermore, in step S1, the volume ratio of styrene, divinylbenzene, and anhydrous ethanol is 0.4-0.6:0.1:4-6.

[0035] Furthermore, in step S2, the mass-to-volume ratio of polyvinylpyrrolidone, poloxamer, ethanol, water, styrene, and KPS solution is 0.8-1.2 g : 0.8-1.2 g : 25-30 mL : 0.8-1.2 mL : 1.8-2.2 mL : 0.8-1.2 mL.

[0036] Furthermore, in step S2, the mass-to-volume ratio of polyvinylpyrrolidone, poloxamer, ethanol, water, styrene, and KPS solution is 1g:1g:26mL:1mL:2mL:1mL.

[0037] Further, in step S2, under N2 protection, ethanol, water, polyvinylpyrrolidone and poloxamer are mixed.

[0038] Furthermore, in step S2, the volume ratio of styrene to styrene in step S1 is 1.8-2.2:0.4-0.6.

[0039] Furthermore, in step S2, the volume ratio of styrene to styrene in step S1 is 2:0.5.

[0040] Furthermore, in step S2, continue stirring at room temperature for 10-20 minutes.

[0041] Furthermore, in step S2, the concentration of the KPS solution is 90-110 mmol / L.

[0042] Furthermore, in step S2, the dripping time is ≤30 min.

[0043] Furthermore, in step S2, the product is washed sequentially with deionized water and anhydrous ethanol.

[0044] Furthermore, in step S3, ethanol is used for washing.

[0045] Furthermore, in step S3, the product is allowed to air dry at room temperature.

[0046] Furthermore, in step S3, the volume ratio of THF, acetone, and styrene in step S2 is 28-32:28-32:1.8-2.2.

[0047] Furthermore, in step (2), the mass-to-volume ratio of reactant 1, toluene, tetramethyldisiloxane and tetraisopropyl titanate is 280-320 mg: 2-3 mL: 60-65 μL: 15-20 μL.

[0048] Furthermore, in step (2), the mass-to-volume ratio of reactant 1, toluene, tetramethyldisiloxane and tetraisopropyl titanate is 300 mg: 2.5 mL: 64 μL: 16 μL.

[0049] Furthermore, in step (2), redistilled toluene is used.

[0050] Furthermore, in step (2), ethanol is used for washing.

[0051] Furthermore, in step (2), the reaction is carried out in a dry Shrek tube under N2 protection.

[0052] The present invention also provides a supported chiral phosphine heterogeneous catalyst prepared by the above method.

[0053] The present invention also provides the application of the above-mentioned supported chiral phosphine heterogeneous catalyst in asymmetric organic catalytic reactions.

[0054] The present invention has the following beneficial effects:

[0055] 1. This invention uses dimethoxymethane (FDA) as a crosslinking agent and employs a simple "one-pot" method to link chiral phosphine and its oxide catalysts containing benzene rings to the benzene rings of a support via Friedel-Crafts alkylation. This simple and efficient method anchors chiral phosphine and its oxide catalysts onto the support. It effectively reduces the cost of heterogeneous loading, minimizes environmental pollution, solves the cumbersome modification process in the immobilization of organic catalysts, and effectively addresses the mass transfer limitations of the catalyst by utilizing the hollow and porous structure of the support.

[0056] 2. Advantages of using concentrated sulfuric acid to catalyze the Friedel-Crafts reaction in this invention: 1) Fast catalytic reaction efficiency. Other Lewis acid catalysts, such as ferric chloride and aluminum trichloride, often require more than 12 hours to catalyze the Friedel-Crafts reaction, while concentrated sulfuric acid can achieve the catalytic purpose in 2 hours; 2) Easy removal after the catalytic reaction. Because it is a liquid, it can be quickly removed by continuous dilution and washing after the reaction. However, solid catalysts such as ferric chloride and aluminum trichloride are mixed with the support, making removal difficult and unable to achieve rapid separation. Attached Figure Description

[0057] Figure 1 This is a process diagram for the preparation of a supported chiral phosphine heterogeneous catalyst.

[0058] Figure 2 SEM image of HMOPNs obtained in Example 1;

[0059] Figure 3 SEM image of HMOPNs@BINAPO obtained in Example 1;

[0060] Figure 4 Solid-state NMR spectra of HMOPNs and HMOPNs@BINAPO in Example 1. Detailed Implementation

[0061] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0062] Example 1:

[0063] A supported chiral phosphine heterogeneous catalyst, the preparation method of which includes the following steps: (process flow is shown in...) Figure 1 )

[0064] (1) Preparation of hollow mesoporous polystyrene nanospheres

[0065] (1.1) Dissolve 0.5 mL of styrene and 0.1 mL of divinylbenzene in 5 mL of anhydrous ethanol to obtain reaction solution one;

[0066] (1.2) Under N2 protection, 26 mL of ethanol, 1 mL of water, 1 g of polyvinylpyrrolidone (PVP, Mw = 58000) and 1 g of poloxamer (F127, Mw = 13000) were mixed in a 250 mL three-necked flask and stirred until dissolved. 2 mL of styrene was added and stirred at room temperature for 15 min. 1 mL of KPS solution (concentration of 100 mmol / L) was added and the temperature was raised to 75 °C and reacted for 2 h. The reaction solution I prepared in step S1 was added dropwise and the addition was completed within 30 min using a peristaltic pump. The reaction was carried out at 75 °C for 22 h. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged at 13000 rpm for 5 min. The supernatant was discarded and the solid was washed with deionized water and anhydrous ethanol in sequence to obtain a white solid.

[0067] (1.3) The white solid obtained in step S2 was dispersed in 30 mL of THF and stirred at room temperature for 6 h to remove the core. After centrifugation at 13000 rpm for 5 min, the supernatant was discarded and dispersed in 30 mL of acetone. After stirring at 65 °C for 12 h to remove the pore-forming agent F127, the solid was centrifuged at 13000 rpm for 5 min, washed with anhydrous ethanol, and dried naturally at room temperature to obtain hollow mesoporous polystyrene nanospheres.

[0068] (2) Preparation of supported chiral phosphine heterogeneous catalysts

[0069] (2.1) Under Ar protection, 100 mg of hollow mesoporous polystyrene nanospheres prepared in step (1.3), 0.2 mmol of chiral phosphine ((S)-BINAPO) and 20 mL of DCE were mixed in a 50 mL dry three-necked flask and stirred at room temperature for 2 h. 4 mmol of FDA (dimethoxymethane) was added and stirred for 10 min. 1.5 mL of concentrated sulfuric acid (98 wt%) was added dropwise and the mixture was heated to 80 °C and reacted for 1 h. The mixture was then cooled to room temperature and centrifuged at 11000 rpm for 5 min. The mixture was washed with deionized water and anhydrous ethanol until the washing solution was neutral and dried naturally to obtain reactant one.

[0070] (2.2) Under N2 protection, 300 mg of reactant I prepared in step (2.1), 2.5 mL of redistilled toluene, 64 μL of tetramethyldisiloxane and 16 μL of tetraisopropyl titanate were mixed in a 20 mL dry Shrek tube, heated to 70 °C and reacted for 30 h. After cooling to room temperature, the mixture was centrifuged at 11000 rpm for 5 min, washed with ethanol, and dried naturally at room temperature to obtain HMOPNs@BINAPO, i.e., the supported chiral phosphine heterogeneous catalyst.

[0071] Example 2:

[0072] A supported chiral phosphine heterogeneous catalyst, the preparation method of which includes the following steps:

[0073] (1) Preparation of hollow mesoporous polystyrene nanospheres

[0074] (1.1) Dissolve 0.4 mL of styrene and 0.1 mL of divinylbenzene in 4 mL of anhydrous ethanol to obtain reaction solution one;

[0075] (1.2) Under N2 protection, 25 mL of ethanol, 0.8 mL of water, 0.8 g of polyvinylpyrrolidone (PVP, Mw = 58000) and 0.8 g of poloxamer (F127, Mw = 13000) were mixed in a 250 mL three-necked flask and stirred until dissolved. 1.8 mL of styrene was added and stirred at room temperature for 10 min. 0.8 mL of KPS solution (concentration of 90 mmol / L) was added and the temperature was raised to 70 °C and reacted for 2.2 h. The reaction solution I prepared in step S1 was added dropwise and the addition was completed within 30 min using a peristaltic pump. The reaction was carried out at 70 °C for 25 h. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged at 13000 rpm for 5 min. The supernatant was discarded and the solid was washed with deionized water and anhydrous ethanol in sequence to obtain a white solid.

[0076] (1.3) The white solid obtained in step S2 was dispersed in 28 mL of THF, stirred at room temperature for 5 h to remove the core, centrifuged at 13000 rpm for 5 min, the supernatant was discarded, and the solid was further dispersed in 28 mL of acetone, stirred at 60 °C for 10 h to remove the pore-forming agent F127, centrifuged at 13000 rpm for 5 min, washed with anhydrous ethanol, and dried naturally at room temperature to obtain hollow mesoporous polystyrene nanospheres.

[0077] (2) Preparation of supported chiral phosphine heterogeneous catalysts

[0078] (2.1) Under Ar protection, in a 50 mL dry three-necked flask, 90 mg of hollow mesoporous polystyrene nanospheres prepared in step (1.3), 0.1 mmol of chiral phosphine ((S)-BINAPO) and 18 mL of DCE were mixed and stirred at room temperature for 1.5 h. 3 mmol of FDA was added and stirred again for 8 min. 1 mL of concentrated sulfuric acid (98 wt%) was added dropwise and the temperature was raised to 75 °C and reacted for 0.8 h. After cooling naturally to room temperature, the mixture was centrifuged at 11000 rpm for 5 min. The mixture was washed successively with deionized water and anhydrous ethanol until the washing solution was neutral and then dried naturally to obtain reactant one.

[0079] (2.2) Under N2 protection, 280 mg of reactant I obtained in step (2.1), 2 mL of redistilled toluene, 60 μL of tetramethyldisiloxane and 15 μL of tetraisopropyl titanate were mixed in a 20 mL dry Shrek tube, heated to 65 °C and reacted for 32 h. After cooling to room temperature, the mixture was centrifuged at 11000 rpm for 5 min, washed with ethanol, and dried naturally at room temperature to obtain the supported chiral phosphine heterogeneous catalyst.

[0080] Example 3:

[0081] A supported chiral phosphine heterogeneous catalyst, the preparation method of which includes the following steps:

[0082] (1) Preparation of hollow mesoporous polystyrene nanospheres

[0083] (1.1) Dissolve 0.6 mL of styrene and 0.1 mL of divinylbenzene in 6 mL of anhydrous ethanol to obtain reaction solution one;

[0084] (1.2) Under N2 protection, in a 250 mL three-necked flask, 30 mL of ethanol, 1 mL of water, 1.2 g of polyvinylpyrrolidone (PVP, Mw = 58000) and 1.2 g of poloxamer (F127, Mw = 13000) were mixed and stirred until dissolved. 2.2 mL of styrene was added, and stirring was continued at room temperature for 20 min. 1.2 mL of KPS solution (concentration of 100 mmol / L) was added, and the temperature was raised to 80 °C and reacted for 1.8 h. The reaction solution I prepared in step S1 was added dropwise, and the addition was completed within 30 min using a peristaltic pump. The reaction was carried out at 80 °C for 20 h. After the reaction was completed, the mixture was naturally cooled to room temperature and centrifuged at 13000 rpm for 5 min. The supernatant was discarded, and the solid was washed successively with deionized water and anhydrous ethanol to obtain a white solid.

[0085] (1.3) The white solid obtained in step S2 was dispersed in 32 mL of THF, stirred at room temperature for 7 h to remove the core, centrifuged at 13000 rpm for 5 min, the supernatant was discarded, and the solid was further dispersed in 32 mL of acetone, stirred at 70 °C for 10 h to remove the pore-forming agent F127, centrifuged at 13000 rpm for 5 min, washed with anhydrous ethanol, and dried naturally at room temperature to obtain hollow mesoporous polystyrene nanospheres.

[0086] (2) Preparation of supported chiral phosphine heterogeneous catalysts

[0087] (2.1) Under Ar protection, in a 50 mL dry three-necked flask, 110 mg of hollow mesoporous polystyrene nanospheres prepared in step (1.3), 0.3 mmol of chiral phosphine ((S)-BINAPO) and 22 mL of DCE were mixed and stirred at room temperature for 2.5 h. 5 mmol of FDA was added and stirred again for 12 min. 2 mL of concentrated sulfuric acid (98 wt%) was added dropwise, and the temperature was raised to 85 °C and reacted for 0.8 h. After cooling naturally to room temperature, the mixture was centrifuged at 11000 rpm for 5 min. The mixture was washed successively with deionized water and anhydrous ethanol until the washing solution was neutral. After drying naturally, reactant one was obtained.

[0088] (2.2) Under N2 protection, 320 mg of reactant I prepared in step (2.1), 3 mL of redistilled toluene, 65 μL of tetramethyldisiloxane and 20 μL of tetraisopropyl titanate were mixed in a 20 mL dry Shrek tube, heated to 75 °C and reacted for 28 h, cooled to room temperature, centrifuged at 11000 rpm for 5 min, washed with ethanol, and dried naturally at room temperature to obtain the supported chiral phosphine heterogeneous catalyst.

[0089] Example 4:

[0090] A supported chiral phosphine heterogeneous catalyst, the preparation method of which includes the following steps: (process flow is shown in...) Figure 1 )

[0091] In step (2.1), the chiral phosphine is (S)-BINAP, and HMOPNs@BINAP is prepared, which is a supported chiral phosphine heterogeneous catalyst. The rest is the same as in Example 1.

[0092] Example 5:

[0093] A supported chiral phosphine heterogeneous catalyst, the preparation method of which includes the following steps: (process flow is shown in...) Figure 1 )

[0094] In step (2.1), the chiral phosphine is (R,R)-DIPAMP, and HMOPNs@DIPAMP, i.e., the supported chiral phosphine heterogeneous catalyst, is prepared. The rest is the same as in Example 1.

[0095] Comparative Example 1:

[0096] A supported chiral phosphine heterogeneous catalyst, the preparation method of which includes the following steps:

[0097] Step (2.2) is excluded; the rest is the same as in Example 1.

[0098] Test case

[0099] I. The hollow mesoporous polystyrene nanospheres (HMOPNs) and the supported chiral phosphine heterogeneous catalyst (HMOPNs@BINAPO) prepared in Example 1 were analyzed by SEM. The results are shown in the figure. Figure 2-3 .

[0100] Depend on Figure 2-3 It can be seen that the support and the supported catalyst of this application have regular morphology and uniform particle size. After the catalyst is loaded, the particle size of the support increases and the surface becomes rough.

[0101] II. The hollow mesoporous polystyrene nanospheres (HMOPNs) and the supported chiral phosphine heterogeneous catalyst (HMOPNs@BINAPO) prepared in Example 1 were subjected to solid-state carbon NMR and phosphorus NMR spectroscopy. The results are shown in [Figure 1]. Figure 4 (a, b, and c are solid-state NMR spectra of HMOPNs) 13 C-spectroscopy, solid-state NMR of HMOPNs@BINAPO 13 C spectrum and 31 P-spectrum).

[0102] Depend on Figure 4 Comparing a and b, we can see that the peaks at 127.74 ppm and 145.77 ppm represent substituted and unsubstituted aromatic carbons in polystyrene, 39.83 ppm is the -CH2 peak in polystyrene, 64.92 ppm is the introduced -CH2OCH3 peak, and 15.10 ppm can be attributed to carbon in the -CH2 crosslinking agent formed by the FC reaction. Figure 4 The peak at 145.77 ppm disappeared in the middle b sample, and the addition of the naphthalene ring framework resulted in a broad peak at 127.83 ppm, indicating that the FDA successfully anchored the catalyst to the support; CP / MAS 31 The PNMR peak at 25.20 ppm corresponds to the peak of phosphorus oxide in the catalyst, further proving that the present invention successfully loaded (S)-BINAPO onto hollow mesoporous polystyrene nanospheres in the form of covalent bonds.

[0103] III. The supported chiral phosphine heterogeneous catalyst (HMOPNs@BINAPO) prepared in Example 1 was used to catalyze the asymmetric aldol reaction of trans-chalcone and aldehyde, yielding a high yield of 91% and enantioselectivity of 94%, demonstrating that the catalyst prepared in this invention possesses excellent catalytic activity. The specific reaction is as follows:

[0104]

[0105] IV. The catalysts prepared in Example 1 and Comparative Example 1 were subjected to heterogeneous reactions under the same conditions. The comparison showed that the catalyst in Example 1 increased the yield of the asymmetric cyclization reaction by 15% and the enantioselectivity by 10% compared with the catalyst in Comparative Example 1, and the reaction activity was greatly increased.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a supported chiral phosphine heterogeneous catalyst, characterized in that, Includes the following steps: (1) Mix hollow mesoporous polystyrene nanospheres, chiral phosphine and DCE, stir, add dimethoxymethane, stir again, add concentrated sulfuric acid dropwise, heat to 75-85℃ and react for 0.8-1.2h, cool to room temperature, centrifuge, wash and dry to obtain reactant one; (2) The reactants I, toluene, tetramethyldisiloxane and tetraisopropyl titanate obtained in step (1) are mixed, heated to 65-75℃ and reacted for 28-32h, cooled to room temperature, centrifuged, washed and dried to obtain a supported chiral phosphine heterogeneous catalyst. In step (1), chiral phosphine is , or .

2. The method for preparing the supported chiral phosphine heterogeneous catalyst according to claim 1, characterized in that, In step (1), the molar ratio of hollow mesoporous polystyrene nanospheres to chiral phosphine is 90-110 mg: 0.1-0.3 mmol.

3. The method for preparing the supported chiral phosphine heterogeneous catalyst according to claim 1, characterized in that, In step (1), the molar volume ratio of chiral phosphine, dimethoxymethane, DCE and concentrated sulfuric acid is 0.1-0.3 mmol: 3-5 mmol: 18-22 mL: 1-2 mL.

4. The method for preparing the supported chiral phosphine heterogeneous catalyst according to claim 1, characterized in that, In step (1), the hollow mesoporous polystyrene nanospheres are prepared by the following method: S1: Dissolve styrene and divinylbenzene in anhydrous ethanol to obtain reaction solution one; S2: Mix ethanol, water, polyvinylpyrrolidone and poloxamer, stir until dissolved, add styrene, continue stirring, add KPS solution, heat to 70-80℃ and react for 1.8-2.2h, add reaction solution one obtained in step S1 dropwise, react at 70-80℃ for 20-25h, cool to room temperature, centrifuge and wash to obtain a white solid; S3: The white solid obtained in step S2 is dispersed in THF and stirred at room temperature for 5-7 hours. After centrifugation, it is further dispersed in acetone and stirred at 60-70℃ for 10-15 hours. After centrifugation, washing and drying, hollow mesoporous polystyrene nanospheres are obtained.

5. The method for preparing the supported chiral phosphine heterogeneous catalyst according to claim 4, characterized in that, In step S1, the volume ratio of styrene, divinylbenzene and anhydrous ethanol is 0.4-0.6:0.1:4-6.

6. The method for preparing the supported chiral phosphine heterogeneous catalyst according to claim 4, characterized in that, In step S2, the mass-to-volume ratio of polyvinylpyrrolidone, poloxamer, ethanol, water, styrene, and KPS solution is 0.8-1.2 g : 0.8-1.2 g : 25-30 mL : 0.8-1.2 mL : 1.8-2.2 mL : 0.8-1.2 mL.

7. The method for preparing the supported chiral phosphine heterogeneous catalyst according to claim 1, characterized in that, In step (2), the mass-to-volume ratio of reactant 1, toluene, tetramethyldisiloxane and tetraisopropyl titanate is 280-320 mg: 2-3 mL: 60-65 μL: 15-20 μL.

8. The supported chiral phosphine heterogeneous catalyst prepared by the method of any one of claims 1-7.

9. The application of the supported chiral phosphine heterogeneous catalyst according to claim 8 in asymmetric organic catalytic reactions.

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