Preparation method of super-crosslinked polymer supported chiral ferrocene catalyst

Abstract

The invention discloses a preparation method of a super-crosslinked polymer supported chiral ferrocene catalyst, and belongs to the technical field of organic chemistry. The preparation method comprises the following steps: in an inert gas atmosphere, dissolving a ligand or a mixture containing the ligand and metal salt in a solvent, stirring at room temperature until the ligand or the mixture is dissolved, then adding an aryl-containing comonomer, and continuously stirring and dissolving to obtain a reaction solution; and adding Lewis acid or Bronsted acid, and carrying out Friedel-Crafts alkylation reaction to obtain the supported chiral ferrocene catalyst. Wherein the ligand is selected from a compound as shown in L1-L12. Compared with a previous covalent bond polymerization method, the loading scheme has the advantages that the catalyst does not need to be modified, and the loading scheme has relatively large application potential aiming at a series of aromatic ring-containing micromolecular catalysts and has the advantages of simplicity, high efficiency and relatively good universality.

Description

Technical Field

[0001] This invention relates to the field of organic chemistry, specifically to a method for preparing a hypercrosslinked polymer-supported chiral ferrocene catalyst. Background Technology

[0002] Ferrocene, as a superior framework, plays a crucial role in the design of chiral ligands and catalysts. Its economic efficiency, thermal stability, and remarkable tolerance to moisture, oxygen, and various reactive reagents have made it a key component in asymmetric catalysis in both academia and industry. Various chiral ferrocene ligands developed to date, when complexed with metals, have exhibited extremely high activity in a variety of asymmetric reactions. However, these chiral ferrocene ligands still have significant drawbacks: complex synthetic routes and demanding preparation conditions lead to high costs; their excellent solubility in organic solvents makes it difficult to separate and recover the catalyst from the reaction system, increasing the difficulty of product purification and hindering the recycling of expensive catalysts, thus limiting their wider industrial application.

[0003] To address the aforementioned issues, immobilizing chiral ferrocene ligands to prepare heterogeneous catalysts holds promise for promoting catalyst reuse and simplifying product purification processes, thereby mitigating these limitations to some extent. To date, numerous chiral heterogeneous chiral ferrocene catalysts have been reported and successfully used in asymmetric reactions. While these achievements are encouraging, many immobilization methods are inherently cumbersome, and the complex synthetic routes make the preparation process time-consuming and costly, contradicting the initial goal of reducing costs through immobilization technology.

[0004] Solvent weaving is a method for preparing hypercrosslinked microporous polymers based on aromatic ring structures. The unique aspect of this innovative method is that it utilizes the solvent itself as a crosslinking agent, thus eliminating the need for additional crosslinking reagents. Compared to previously reported synthetic schemes, this method significantly simplifies the polymerization process. However, previous studies have mainly focused on immobilizing small-molecule chiral phosphates or achiral ligands; there are currently no reports of applying this HCP method to chiral ligand / metal complexes. Its application to the immobilization of chiral ligand / metal complexes still faces many challenges: (1) Challenges in maintaining the chiral environment: The intense reaction conditions during crosslinking may cause the stereoconfiguration of chiral ligands to race or be destroyed, making it difficult to maintain the original chiral microenvironment.

[0005] (2) Stability of metal active centers: Under the highly active conditions of cross-linking reaction, metal complexes may undergo dissociation or redox reactions, leading to deactivation of active centers or structural changes.

[0006] (3) Difficulty in controlling the uniformity of ligand loading: Since chiral ligands usually have complex spatial structures, their uniform distribution and directional fixation in cross-linked networks face great challenges, which can easily lead to uneven distribution of active sites.

[0007] (4) Matching of pore structure and catalytic activity: Chiral catalytic reactions often require a specific spatial environment, while the random pore structure formed by cross-linking may not provide an ideal chiral cavity, affecting stereoselectivity.

[0008] (5) Maintaining structural integrity during post-processing: Crosslinked products usually require strong acid treatment to remove the catalyst, which may further damage the coordination structure of the chiral ligand-metal. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention proposes a method for preparing a hypercrosslinked polymer-supported chiral ferrocene catalyst.

[0010] In a first aspect, this application provides a method for preparing a supported chiral ferrocene catalyst, comprising the following steps: (1) Under an inert gas atmosphere, dissolve the ligand or a mixture containing the ligand and the metal salt in a solvent and stir at room temperature until dissolved to obtain a reaction solution; (2) Add Lewis acid or Brønsted acid to the reaction solution to carry out Friedel-Crafts alkylation reaction to obtain a supported chiral ferrocene catalyst.

[0011] In some embodiments, the preparation method includes the following steps: (1) Under an inert gas atmosphere, the ligand or a mixture containing the ligand and the metal salt is dissolved in a solvent and stirred at room temperature until dissolved. Then, an aryl-containing comonomer is added and stirred until dissolved to obtain a reaction solution. (2) A Lewis acid or a Brønsted acid is added to the reaction solution to carry out a Friedel-Crafts alkylation reaction, yielding a supported chiral ferrocene catalyst. The reaction route of the preparation method is shown below. Figure 1 .

[0012] In some embodiments, the ligand is selected from the compounds shown in L1-L12: ; And / or, the metal salts include [Rh(COD)Cl]2, [Ir(COD)Cl]2, [Rh(COD)2]BF4, [Rh(COD)2]SbF6, [Rh(COD)2]BARF; And / or, the amount of metal salt used relative to the ligand is 0.5-1 equivalent.

[0013] In some embodiments, the aryl-containing comonomer comprises compounds represented by C1-C7: ; and / or ; the amount of the aryl-containing comonomer added relative to the ligand is 1-10 equivalents.

[0014] In some embodiments, the solvent comprises the compounds shown in S1-S6: ; And / or; add solvent to achieve a ligand concentration of 0.01-1 mmol / ml; and / or; add solvent, stir at room temperature until completely dissolved, and continue stirring for 10-60 minutes.

[0015] In some embodiments, the Lewis acid includes at least one of ferric chloride, aluminum chloride, and tin tetrachloride, and / or the Brønsted acid includes at least one of concentrated sulfuric acid and trifluoromethanesulfonic acid; and / or the amount of Lewis acid or Brønsted acid relative to the ligand is 5-75 equivalents; and / or the catalyst (Lewis acid or Brønsted acid) is added under an inert gas flow. Adding under an inert gas flow ensures that no air enters and damages the catalyst structure.

[0016] In some embodiments, after adding Lewis acid or Brønsted acid to the reaction solution, the reaction vessel is sealed.

[0017] In some embodiments, the reaction time of the Friedel-Crafts alkylation reaction is 1 h to 48 h, more preferably 8 h to 48 h; the reaction is quenched using a quenching agent, the quenching agent including at least one of anhydrous ethanol, anhydrous methanol, and aqueous hydrochloric acid.

[0018] In some embodiments, after quenching the reaction with a quenching agent, the reaction apparatus is moved to room temperature. After the reaction system slowly returns to room temperature, it is vigorously stirred for 25-40 minutes until all the lumpy solids are turned into powder. The purpose of vigorous stirring is because the resulting solids tend to clump together, which needs to be broken down by mechanical stirring to turn them into powder.

[0019] In some embodiments, the reaction temperature of the Friedel-Crafts alkylation reaction is -20°C to 80°C, and more preferably -10°C to 60°C.

[0020] In some embodiments, after the Friedel-Crafts alkylation reaction is quenched, the reaction tube is moved to room temperature. After the reaction system is slowly brought to room temperature, it is stirred vigorously for 25-40 min until all the blocky solids are turned into powder. The mixture is then filtered, and the filter cake is washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. Finally, it is extracted with anhydrous ethanol using a Soxhlet extracter for 45-50 h to obtain the supported catalyst.

[0021] Secondly, this application provides a supported chiral ferrocene catalyst, which is prepared by the method described in any of the above-mentioned methods.

[0022] In some embodiments, the supported chiral ferrocene catalyst has the following general formula: ; R represents H, CH3, or CF3 in the para or meta position, R' represents H or CH3, Z represents S or O, x=1, and y=0-10.

[0023] The structure of this supported catalyst is reported for the first time. Compared with previous supported catalysts, this catalyst has a diverse structure, and its synthesis scheme is simple, efficient, and low-cost. Furthermore, different metals and comonomers can be introduced during the polymerization process to flexibly adjust the structure of the supported catalyst, making it suitable for different reactions.

[0024] In some embodiments, the supported chiral ferrocene catalyst has a structural formula selected from any of the following: ; ; ; ; ; ; .

[0025] Thirdly, this application provides the application of the supported chiral ferrocene catalyst in asymmetric hydrogenation reactions, wherein the substrate is benzoxazinone.

[0026] In summary, compared with the prior art, the technical solution of this application achieves the following technical effects: Compared to previous covalent polymerization methods, this supported catalyst method does not require catalyst modification and has significant application potential for a range of small molecule catalysts containing aromatic rings. It offers advantages such as simplicity, high efficiency, and good versatility. Furthermore, the comonomers used in this polymerization method are widely available, including aromatic rings, aromatic heterocycles, and their derivatives. Compared to polymerizable monomers with higher structural requirements, such as styrene and other α-olefin structures, this polymerization method can yield supported catalysts with more diverse structures.

[0027] This supported catalyst exhibits excellent catalytic activity and good stability in asymmetric hydrogenation reactions. The product can be obtained simply by solvent extraction followed by distillation, without the need for column chromatography. In the examples, the supported catalyst showed no change in activity after 10 cycles of recycling.

[0028] The technical solution of this application provides an important reference for the simple and efficient preparation of supported catalysts, and has great academic research value and industrial application prospects. Attached Figure Description

[0029] Figure 1 This is a reaction route diagram for the preparation of supported catalysts.

[0030] Figure 2 The results are from the BET test of the supported catalyst SL / Ir-5.

[0031] Figure 3 The results are from SEM analysis of the supported catalyst SL / Ir-5.

[0032] Figure 4 The results are from SEM analysis of the supported catalyst SL / Ir-5.

[0033] Figure 5 The results are EDS test results for the supported catalyst SL / Ir-5.

[0034] Figure 6 The XPS test results are for the supported catalyst SL / Ir-5.

[0035] Figure 7 The effect of recycling the supported catalyst SL / Ir-5. Detailed Implementation

[0036] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0037] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0038] Terminology in this application: Supported catalyst is a chemical term published by the National Committee for Terminology in Science and Technology in 2019. It originates from the first edition of "Chemical Terminology (II) - Basic Organic Chemicals," and refers to a catalyst in which the active component is supported on the surface of a carrier. This type of catalyst is widely used in oil refining, hydrogen peroxide synthesis, and selective oxidation reactions.

[0039] The enantiomeric excess (ee) value is an indicator used to describe the enantiomeric excess in a compound sample. In a chiral molecule, each of the two enantiomeric forms rotated plane-polarized light to a specific angle with the same numerical value but opposite directions; this property is called optical activity. The enantiomeric composition of a compound sample can be described using the term "enantiomeric excess" or "ee%". It indicates the excess of one enantiomeric form over another, usually expressed as a percentage.

[0040] In existing technologies, traditional covalent polymerization requires first modifying the catalyst molecule with complex functional groups (such as adding vinyl, amino, carboxyl groups, etc.), and then attaching it to the polymer backbone (such as polystyrene) through covalent bonds. This is essentially "covalent anchoring".

[0041] Compared to previous covalent polymerization methods, the loading scheme in this application eliminates the need for catalyst modification. Utilizing the characteristics of the Friedel-Crafts alkylation reaction, the catalyst ligand is directly woven into a polymer network as a monomer. Furthermore, this application reveals that the introduced aryl-containing comonomer acts as a crosslinking point during the Friedel-Crafts alkylation reaction, being directly woven into a rigid three-dimensional polymer network. This is essentially similar to "physical embedding" or "in-situ trapping," but with robust chemical crosslinking.

[0042] This solvent-woven loading technology is revolutionary because it shifts the focus from "how to modify the catalyst to suit polymerization" to "how to directly polymerize using the inherent structure of the introduced comonomer." Through a simple, universal, and powerful strategy, it successfully addresses the core pain points of traditional covalent polymerization methods, such as cumbersome steps, poor universality, and high costs. This opens up a highly attractive new path for the preparation and recycling of heterogeneous catalysts from chiral ferrocene ligands.

[0043] The technical solution of this application has a very wide range of sources for the comonomers used. Aromatic rings, aromatic heterocycles and their derivatives can all be directly used as comonomers in this application.

[0044] Compared to traditional methods with their long synthetic routes and numerous steps, including modification, purification, and polymerization, the synthetic route of this application is extremely simple, which significantly shortens the preparation time and greatly reduces costs.

[0045] This application provides the synthesis of a supported chiral ferrocene catalyst, and the reaction route is shown below: .

[0046] The ligands include, but are not limited to, L1-L12. Ligand / metal complexes are formed by dissolving the ligand and metal salt in a solution at a certain molar ratio (ligand:metal = 1:(0.5-1)) and stirring for a period of time. The metal salts include, but are not limited to: [Rh(COD)Cl]2, [Ir(COD)Cl]2, [Rh(COD)2]BF4, [Rh(COD)2]SbF6, and [Rh(COD)2]BARF.

[0047]

[0048] Comonomers include, but are not limited to:

[0049] Solvents include, but are not limited to:

[0050] Weigh either of the following raw materials, A or B, into a reaction tube at room temperature: (A) Ligand; or; (B) Ligands and metal salts with a molar ratio of 1:(0.5-1); After purging the reaction tube three times with an inert gas (nitrogen or argon), add solvent to dissolve the raw materials. Stir at room temperature until the raw materials are completely dissolved, and continue stirring for 10-60 minutes. Then add the aryl-containing comonomer and continue stirring until the comonomer is completely dissolved. Move the reaction tube to an appropriate temperature (-20 to 80°C) and add the catalyst (catalysts include Lewis acids such as ferric chloride, aluminum chloride, and tin tetrachloride, or Brønsted acids such as concentrated sulfuric acid and trifluoromethanesulfonic acid) under inert gas protection. Continue stirring until a large amount of solid precipitates in the reaction solution (1-48 h). Then quench the reaction solution with dilute hydrochloric acid or alcohol. Move the reaction tube to room temperature and, after the reaction system returns to room temperature, stir thoroughly (or vigorously) until the lumpy solid becomes powder. Centrifuge the reaction solution containing the solids, filter, and then use Soxhlet extraction to remove residual impurities (Soxhlet extraction uses solvents such as anhydrous ethanol, anhydrous methanol, and dichloromethane) to obtain the supported catalyst SL-n or SL / Mn.

[0051] In the nomenclature, M represents metal. Supported catalyst SL-n, which does not contain M, indicates that it contains no metal and is obtained through ligand polymerization. Supported catalyst SL / Mn, which contains M, is obtained by the polymerization of ligand / metal complexes formed by the complexation of metal and ligands.

[0052] After synthesizing the supported catalyst (SL / Mn), its activity was further evaluated using an asymmetric hydrogenation reaction of the benzoxazinone substrate. The reaction route is shown below:

[0053] The asymmetric hydrogenation reaction comprises the following steps: In a nitrogen-filled glove box, the supported catalyst SL / Mn (5 μmol, 1 mol%) is weighed into a 5 mL ampoule. 2 mL of anhydrous tetrahydrofuran is added to the reaction flask and stirred until the supported catalyst is uniformly dispersed in the tetrahydrofuran. Subsequently, benzoxazinone a (0.5 mmol) and a 4 M HCl / dioxane solution (0.125 mL, 0.5 mmol, 1 eq.) are added sequentially to the solution. The ampoule is placed in a 50 mL stainless steel autoclave. After sealing the autoclave, it is removed from the glove box. The gas inside the autoclave is replaced three times with hydrogen, and then hydrogen is introduced again until the pressure reaches 45 atm. After stirring at room temperature for 24 h, the pressure is released to release hydrogen in a well-ventilated area. The reaction solution is filtered, and the filter cake is washed with ethyl acetate. Saturated sodium bicarbonate solution is added to the filtrate to quench the hydrochloric acid, and the mixture is stirred for 5 min (to neutralize residual HCl) before separation. After separation, the aqueous phase was extracted twice with ethyl acetate (10 mL × 2), and the organic phases were combined. The organic phase was dried over anhydrous sodium sulfate, filtered, evaporated to dryness under reduced pressure, and the crude product was weighed and the yield was determined by NMR. The ee value of the product was determined by HPLC under the following conditions: DaicelChiralpak AD-H column, isocratic elution: n-hexane / 2-propanol 85:15, flow rate 1 mL / min, column temp 30 °C, retention times (min): 11.663 (major), 18.007 (minor).

[0054] After synthesizing the supported catalyst (SL-n), its activity was further evaluated using an asymmetric hydrogenation reaction of the benzoxazinone substrate. The reaction route is shown below:

[0055] The asymmetric hydrogenation reaction comprises the following steps: In a nitrogen-filled glove box, the supported catalyst SL-n (5 μmol, 1 mol%) and the corresponding metal salt (5 μmol, 1 mol%) are weighed into a 5 mL ampoule. 2 mL of anhydrous tetrahydrofuran is added to the reaction flask, and the mixture is stirred at room temperature for 30 min. Benzooxazinone a (0.5 mmol) and a 4 M HCl / dioxane solution (0.125 mL, 0.5 mmol, 1 eq.) are added sequentially to the solution in the reaction flask. The ampoule is placed in a 50 mL stainless steel autoclave, which is then sealed and removed from the glove box. The gas inside the autoclave is replaced three times with hydrogen, and then hydrogen is introduced again until the pressure reaches 45 atm. After stirring at room temperature for 24 h, the pressure is released to release hydrogen in a well-ventilated area. The reaction solution is filtered, and the filter cake is washed with ethyl acetate. Saturated sodium bicarbonate solution is added to the filtrate to quench the hydrochloric acid, and the mixture is stirred for 5 min (to neutralize residual HCl) before separation. After separation, the aqueous phase was extracted twice with ethyl acetate (10 mL × 2), and the organic phases were combined. The organic phase was dried over anhydrous sodium sulfate, filtered, evaporated to dryness under reduced pressure, and the crude product was weighed and the yield was determined by NMR. The ee value of the product was determined by HPLC under the following conditions: Daicel Chiralpak AD-H column, isocratic elution: n-hexane / 2-propanol 85:15, flow rate 1 mL / min, column temp 30 °C, retention times (min): 11.663 (major), 18.007 (minor).

[0056] The ligands L1-L12 used in the examples were prepared in accordance with the literature Org. Lett. 2013, 15(15), 4014-4017 and Chemical Science 2019, 10(8), 2507-2512.

[0057] The present application will be further explained and described below with reference to specific embodiments.

[0058] Example 1 L1 ligand (60 mg, 0.075 mmol) was weighed into a reaction tube at room temperature. After purging with inert gas three times, chloroform (2 ml) was added. Once the L1 ligand was completely dissolved, stirring continued for 30 min. Anhydrous tin tetrachloride (289 mg, 1.1 mmol) was added under an argon flow. The reaction tube was sealed and the reaction was carried out at room temperature for 12 h (with continuous stirring during the reaction). Then, 1 M hydrochloric acid aqueous solution was added to quench the reaction. The mixture was stirred vigorously at room temperature for 30 min until all the lumpy solids were pulverized. The mixture was filtered, and the filter cake was washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. It was then extracted with anhydrous ethanol using a Soxhlet extract for 48 h to obtain 12 mg of brown supported catalyst SL-1. The structural formula of catalyst SL-1 is as follows: .

[0059] The low yield of the supported catalyst may be due to insufficient tin tetrachloride, resulting in a large amount of ligands being dissolved in the organic solvent.

[0060] Example 2 L1 ligand (60 mg, 0.075 mmol) was weighed into a reaction tube at room temperature. After purging with inert gas three times, chloroform (2 ml) was added. After the ligand was completely dissolved, stirring was continued for 30 min. Anhydrous aluminum trichloride (372 mg, 2.8 mmol) was added under an argon flow. The reaction tube was sealed and reacted at room temperature for 12 h (with continuous stirring during the reaction). Then, 1 M hydrochloric acid aqueous solution was added to quench the reaction. The mixture was stirred vigorously at room temperature for 30 min until all the lumpy solids were pulverized. The mixture was filtered, and the filter cake was washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. It was then extracted with anhydrous ethanol using a Soxhlet extracter for 48 h to obtain 50 mg of brown supported catalyst SL-2. The structural formula of catalyst SL-2 is as follows: .

[0061] The method for preparing the supported catalyst yields a product yield of 87%.

[0062] The supported catalyst was used for an asymmetric hydrogenation reaction (using SL-2+[Rh(COD)Cl]2 as a catalyst), with a product yield of 92% and an ee of 88%.

[0063] Example 3 Weigh L3 ligand (60 mg, 0.076 mmol) and [Rh(COD)Cl]2 (17 mg, 0.037 mmol) into a reaction tube at room temperature. After purging with inert gas three times, add chloroform (2 ml). After the ligand and metal salt are completely dissolved, continue stirring for 30 min. Then add 20 mg of diphenylmethane (Cl) (0.12 mmol) to the reaction solution and continue stirring for 10 min. Then add anhydrous ferric chloride (850 mg, 5.2 mmol) under an argon flow. Seal the reaction tube and heat to 50 °C for 24 h (stirring continuously during the reaction). Then add 1 M hydrochloric acid aqueous solution to quench the reaction. The reaction tube was moved to room temperature. After the reaction system slowly cooled to room temperature, it was vigorously stirred for 30 min until all the lumpy solids turned into powder. The mixture was filtered, and the filter cake was washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. Then, it was extracted with anhydrous ethanol using a Soxhlet extracter for 48 h to obtain 87 mg of the brown supported catalyst SL / Rh-4. The structural formula of catalyst SL / Rh-4 is as follows. .

[0064] The preparation method of the supported catalyst yields a product yield of >99%.

[0065] The supported catalyst was used in an asymmetric hydrogenation reaction, with a product yield of 60% and an ee of 97%. The low product yield may be due to the rhodium catalyst being less active than the iridium catalyst for this substrate.

[0066] Example 4 Weigh L3 ligand (60 mg, 0.076 mmol) and [Ir(COD)Cl]2 (23 mg, 0.037 mmol) into a reaction tube at room temperature. After purging with inert gas three times, add chloroform (2 ml). After the ligand and metal salt are completely dissolved, continue stirring for 30 min. Then add 30 mg of triphenylmethane (C2) (0.15 mmol) to the reaction solution and continue stirring for 10 min. Then add anhydrous ferric chloride (850 mg, 5.2 mmol) under an argon flow. Seal the reaction tube and heat to 50 °C for 24 h (stirring continuously during the reaction). Then add 1 M hydrochloric acid aqueous solution to quench the reaction. The reaction tube was moved to room temperature, and after the reaction system slowly cooled to room temperature, it was vigorously stirred for 30 min until all the lumpy solids turned into powder. The mixture was then filtered, and the filter cake was washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. Finally, it was extracted with anhydrous ethanol using a Soxhlet extracter for 48 h to obtain 105 mg of the brown supported catalyst SL / Ir-5. The structural formula of catalyst SL / Ir-5 is as follows: The method for preparing the supported catalyst yields a product yield of >99%.

[0067] The supported catalyst was used in an asymmetric hydrogenation reaction, with a product yield of 98% and an ee of 98%.

[0068] Example 5 At room temperature, L7 ligand (60 mg, 0.082 mol) and [[Rh(COD)Cl]2 (17 mg, 0.037 mmol) were weighed into a reaction tube. After purging with inert gas three times, chloroform (2 ml) was added. After the ligand and metal salt were completely dissolved, the mixture was stirred for 30 min. Then, 20 mg of furan (C5) (0.3 mmol) was added to the reaction solution, and the mixture was stirred for another 10 min. Concentrated sulfuric acid (200 μL, 3.6 mmol) was added under an argon flow. The reaction tube was sealed and the reaction was carried out at room temperature for 48 h (with continuous stirring during the reaction). Subsequently, 1 M hydrochloric acid aqueous solution was added to quench the reaction. The mixture was stirred vigorously at room temperature for 30 min until all the lumpy solids were turned into powder. The mixture was filtered, and the filter cake was washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. Then, it was extracted with anhydrous ethanol by Soxhlet extraction for 48 h to obtain 82 mg of brown supported catalyst SL / Rh-8. The structural formula of catalyst SL / Rh-8 is as follows. The method for preparing the supported catalyst yields a product yield of 85%.

[0069] The supported catalyst was used in an asymmetric hydrogenation reaction, with a product yield of 95% and an ee of 98%.

[0070] Example 6 Weigh L7 ligand (60 mg, 0.082 mmol) and [[Rh(COD)Cl]2 (17 mg, 0.037 mmol) into a reaction tube at room temperature. After purging with inert gas three times, add chloroform (2 ml). After the ligand and metal salt are completely dissolved, continue stirring for 30 min. Then add 20 mg of thiophene (C6) (0.33 mmol) to the reaction solution and continue stirring for 10 min. Then add concentrated sulfuric acid (200 μL, 3.2 mmol) under an argon flow. Seal the reaction tube and react at room temperature for 48 h (with continuous stirring during the reaction). Then add 1 M hydrochloric acid aqueous solution to quench the reaction. Stir vigorously at room temperature for 30 min until all the lumpy solids become powder. Filter, and wash the filter cake alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. Then extract with anhydrous ethanol by Soxhlet extraction for 48 h to obtain 72 mg of brown supported catalyst SL / Rh-9. The structural formula of catalyst SL / Rh-9 is as follows. The method for preparing the supported catalyst yields a product yield of 74%.

[0071] The supported catalyst was used in an asymmetric hydrogenation reaction, with a product yield of 88% and an ee of 90%.

[0072] Example 7 At room temperature, L9 ligand (60 mg, 0.082 mmol) and [Rh(COD)2]BF4 (15 mg, 0.037 mmol) were weighed into a reaction tube. After purging with inert gas three times, chloroform (2 ml) was added. After the ligand and metal salt were completely dissolved, stirring was continued for 30 min. The temperature was lowered to 0℃, and anhydrous aluminum trichloride (698 mg, 5.2 mmol) was added under an argon flow. The reaction tube was sealed, and the temperature was lowered to 0℃ for 12 h (with continuous stirring during the reaction). Then, 1 M hydrochloric acid aqueous solution was added to quench the reaction. The reaction tube was moved to room temperature, and after the reaction system was slowly heated to room temperature, it was vigorously stirred for 30 min until all the lumpy solids turned into powder. The mixture was filtered, and the filter cake was washed alternately with saturated sodium bicarbonate aqueous solution, anhydrous ethanol, and dichloromethane. Then, it was extracted with anhydrous ethanol using a Soxhlet extracter for 48 h to obtain 72 mg of the brown supported catalyst SL / Rh-11. The structural formula of catalyst SL / Rh-11 is as follows. The method for preparing the supported catalyst yields a product yield of 96%.

[0073] The supported catalyst was used in an asymmetric hydrogenation reaction, with a product yield of 92% and an ee of 88%.

[0074] The reaction parameters and results of the above embodiments are summarized in Table 1. By changing the selection of ligands, solvents, metal salts, comonomers, catalysts, and reaction temperatures (°C), more embodiments were obtained.

[0075] The results are shown in Table 1. The naming convention in Table 1 is: Example 1 indicates Example 1, and so on. The yield is the yield for preparing the supported catalyst.

[0076] Table 1

[0077]

[0078] Experimental results show that while solid catalysts with considerable yields can be obtained in the examples without added comonomers, their catalytic performance has room for improvement. Further research in this application revealed that the introduction of comonomers not only significantly improves the dispersibility of the metal salt, allowing for full exposure of active sites and thus enhancing catalytic efficiency, but also facilitates the construction of diverse catalyst structures, enabling them to adapt to different reaction systems and achieve superior catalytic effects. Based on this, the prepared catalyst possesses superior catalytic performance and broader system applicability.

[0079] Test case The supported catalyst SL / Ir-5 prepared in Example 4 was tested and its performance was characterized.

[0080] See results Figures 2-6 .

[0081] in, Figure 2 The results are from the BET test of the supported catalyst SL / Ir-5. Figure 3 and Figure 4 The results are from SEM analysis of the supported catalyst SL / Ir-5. Figure 5 The results are EDS test results for the supported catalyst SL / Ir-5. Figure 6 The XPS test results are for the supported catalyst SL / Ir-5.

[0082] Characterization results show that the prepared supported catalyst SL / Ir-5 possesses a large number of mesoporous structures and a small number of microporous structures, which is significantly different from the macroporous structures obtained by conventional α-olefin copolymerization. EDS distribution results show that the metal and ligands are uniformly distributed in the supported catalyst without obvious clustering, indicating good dispersion performance. XPS results show that the valence states of phosphine and iridium in the supported catalyst remain consistent with those of the starting materials, proving that the catalyst can exist stably during polymerization.

[0083] Application example: The supported catalysts prepared in the above examples were used for asymmetric hydrogenation reactions. The reaction steps were as described above, and the experimental results are shown at the end of each example.

[0084] Cyclic reaction of supported catalysts To verify the stability of the supported catalyst, this application used the most active supported catalyst, SL / Ir-5, for cyclic experiments. The cyclic experiment was conducted as follows: In a nitrogen-filled glove box, the supported catalyst SL / Ir-5 (5 μmol, 1 mol%) was weighed into a 5 mL ampoule. 2 mL of anhydrous tetrahydrofuran was added to the reaction flask, and the mixture was stirred for 10 min. Then, benzoxazinone a was added sequentially to the solution in the reaction flask. (0.5 mmol) and a 4 M HCl / dioxane solution (0.125 mL.5 mmol, 1 eq.). Ampoules were placed in a 50 mL stainless steel high-pressure reactor. After sealing the reactor, it was removed from the glove box. The gas inside the reactor was replaced three times with hydrogen, and then hydrogen was introduced until the pressure reached 45 atm. After stirring at room temperature for 24 h, the pressure was released in a well-ventilated area to release hydrogen. The reaction solution was filtered, and the filter cake was washed with ethyl acetate. The washed filter cake was vacuum dried at room temperature for 24 h and then used directly in the next cycle. Saturated sodium bicarbonate solution was added to the filtrate to quench the hydrochloric acid, and the mixture was stirred for 5 min (to neutralize residual HCl) before separation. The aqueous phase was extracted twice with ethyl acetate (10 mL × 2), and the organic phases were combined. The organic phase was dried over anhydrous sodium sulfate, filtered, and evaporated under reduced pressure to obtain the target product b. .

[0085] The yield of the crude product was determined by NMR spectroscopy after weighing; the ee value of the product was determined by HPLC. The results of the catalytic experiments are shown below. Figure 7 .

[0086] After 10 cycles, ICP-OES results showed that the leaching of Ir in the supported catalyst was only 3%, demonstrating good stability. In the tenth cycle, the supported catalyst still maintained a 99% yield and a 98% ee value in the asymmetric hydrogenation reaction, exhibiting activity comparable to that of the homogeneous catalyst, reducing the catalyst cost to 1 / 10 of that of the homogeneous catalyst. Although the cyclic experiment only conducted 10 cycles, its stable catalytic performance indicates that the supported catalyst has the potential for long-term stable operation.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a supported chiral ferrocene catalyst, characterized in that, Includes the following steps: (1) Under an inert gas atmosphere, dissolve the ligand or a mixture containing the ligand and the metal salt in a solvent and stir at room temperature until dissolved to obtain a reaction solution; (2) Add Lewis acid or Brønsted acid to the reaction solution to carry out Friedel-Crafts alkylation reaction to obtain a supported chiral ferrocene catalyst.

2. The preparation method according to claim 1, characterized in that, Includes the following steps: (1) Under an inert gas atmosphere, the ligand or a mixture containing the ligand and the metal salt is dissolved in a solvent and stirred at room temperature until dissolved. Then, an aryl-containing comonomer is added and stirred until dissolved to obtain a reaction solution. (2) Add Lewis acid or Brønsted acid to the reaction solution to carry out Friedel-Crafts alkylation reaction to obtain a supported chiral ferrocene catalyst.

3. The preparation method according to claim 1 or 2, characterized in that, The ligands are selected from the compounds shown in L1-L12: ； And / or, the metal salts include [Rh(COD)Cl]2, [Ir(COD)Cl]2, [Rh(COD)2]BF4, [Rh(COD)2]SbF6, [Rh(COD)2]BARF; And / or, the amount of metal salt used relative to the ligand is 0.5-1 equivalent.

4. The preparation method according to claim 1 or 2, characterized in that, The aryl-containing comonomers include compounds represented by C1-C7: ; and / or ; the amount of the aryl-containing comonomer added relative to the ligand is 1-10 equivalents.

5. The preparation method according to claim 1 or 2, characterized in that, The solvent includes the compounds shown in S1-S6: ； And / or; add solvent to achieve a ligand concentration of 0.01-1 mmol / ml; and / or; add solvent, stir at room temperature until completely dissolved, and continue stirring for 10-60 minutes.

6. The preparation method according to claim 1 or 2, characterized in that, The Lewis acid includes at least one of ferric chloride, aluminum chloride, and tin tetrachloride, and / or the Brønsted acid includes at least one of concentrated sulfuric acid and trifluoromethanesulfonic acid; and / or; The amount of Lewis acid or Brønsted acid relative to the ligand is 5-75 equivalents; and / or, the addition of Lewis acid or Brønsted acid is carried out under an inert gas flow.

7. The preparation method according to claim 1 or 2, characterized in that, The reaction time of the Friedel-Crafts alkylation reaction is 1 h to 48 h, and the reaction is quenched using a quenching agent, which includes at least one of anhydrous ethanol, anhydrous methanol, and hydrochloric acid aqueous solution; and / or; the reaction temperature of the Friedel-Crafts alkylation reaction is -20 °C to 80 °C.

8. A supported chiral ferrocene catalyst, characterized in that, The supported chiral ferrocene catalyst is prepared by the method described in any one of claims 1-7.

9. A supported chiral ferrocene catalyst, characterized in that, The supported chiral ferrocene catalyst has the following general formula: ； R represents H, CH3, or CF3 in the para or meta position, R' represents H or CH3, Z represents S or O, x=1, and y=0-10.

10. The application of the supported chiral ferrocene catalyst as described in any one of claims 8-9 in asymmetric hydrogenation reactions.

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