A chiral nanoparticle catalytic system for asymmetric Michael addition reactions and its applications

Abstract

This invention belongs to the field of catalyst technology, specifically relating to a chiral nanoparticle catalytic system for asymmetric Michael addition reactions and its applications. The chiral nanoparticle catalytic system comprises a supported Ni metal nanoparticle catalyst with silica as a support and substituted benzyl-derived chiral modifying molecules; the substituted benzyl-derived chiral modifying molecules are used to generate active species in situ during the reaction. The supported Ni metal nanoparticle catalyst prepared by this invention can be recovered through simple filtration, washing, and drying; the recovery of the benzyl-derived chiral modifying molecules can be achieved through simple acid treatment, water backwashing of the oil phase, and subsequent alkalization. The heterogeneous chiral metal nanoparticle catalytic system prepared by this invention exhibits higher reactivity and comparable enantioselectivity than homogeneous Ni-diamine complexes in the asymmetric addition reaction of dimethyl malonate with β-nitrostyrene compounds.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a chiral nanoparticle catalytic system for asymmetric Michael addition reactions and its applications. Background Technology

[0002] Heterogeneous chiral catalysis offers significant advantages over homogeneous chiral catalysis in product separation and purification, catalyst recycling, and is more suitable for continuous flow reactors. Therefore, heterogeneous chiral catalysis has broad industrial application prospects. Catalytic reactions for the formation of asymmetric carbon-carbon bonds are an important means of constructing the basic carbon skeleton of target molecules with chiral centers, thus holding a very important position in organic synthetic chemistry. However, most studies on asymmetric carbon-carbon bond formation reactions typically focus on homogeneous catalytic systems, and the amount of catalyst used is usually relatively high. This means that a large amount of metals and chiral ligands are difficult to recover after the reaction, resulting in catalyst waste. Therefore, the development of efficient heterogeneous chiral catalytic systems for asymmetric carbon-carbon bond formation reactions has attracted widespread attention.

[0003] Currently, research on heterogeneous chiral catalytic systems mainly falls into two categories: supported heterogeneous chiral catalytic systems and heterogeneous chiral nanoparticle catalytic systems. Supported heterogeneous chiral catalytic systems are further divided into chiral molecular catalysts supported by covalent or non-covalent bonds. The advantage of this type of catalyst is its relatively simple design; by functionalizing chiral molecules, the obtained solid chiral catalysts usually retain some of the characteristics of molecular catalysts. However, the immobilization of these catalysts often leads to distortion of the reaction transition state, resulting in a decrease in activity and product selectivity. Furthermore, the derivatization of chiral molecules places higher demands on the synthesis. The second type of catalyst combines metal nanoparticles with chiral ligands to achieve asymmetric catalytic reactions, avoiding the complex ligand derivatization process. However, the development of this type of catalytic system is relatively limited, and the reaction performance and types are relatively restricted. Despite the progress in heterogeneous chiral catalysis, developing heterogeneous systems to improve the activity and selectivity of asymmetric carbon-carbon bond formation reactions remains a challenging task. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for preparing and applying a supported nickel catalytic system for catalyzing asymmetric Michael addition reactions, aiming to overcome the disadvantages of existing catalytic systems that are difficult to recover and have poor reaction performance.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In one aspect, this invention provides a chiral nanoparticle catalytic system for asymmetric Michael addition reactions. The chiral nanoparticle catalytic system includes a supported Ni metal nanoparticle catalyst with silica as a support and a substituted benzyl-derived chiral modified molecule. The substituted benzyl-derived chiral modified molecule is used to generate active species in situ during the reaction.

[0007] In the above technical solution, further, in the catalytic system, the content of the substituted benzyl-derived chiral modified molecule is 1-10 mol%, and the content of Ni metal is 1-20 wt%.

[0008] In the above technical solution, the preparation method of the supported Ni metal nanoparticle catalyst is one of the following two methods:

[0009] Method 1: Strong electrostatic adsorption method

[0010] Includes the following steps:

[0011] (1) Dissolve the Ni source in deionized water, add ammonia to adjust the pH of the Ni source aqueous solution to 9-13, forming [Ni(NH3)6]. 2+ Species solution;

[0012] (2) Add the silica support to the solution obtained in step (1) and stir at room temperature for 4-8 hours to allow the [Ni(NH3)6] to react. 2+ Species are adsorbed onto the silica support;

[0013] (3) The mixture obtained in step (2) is filtered, the solid is dried, calcined in air, and then reduced in a hydrogen atmosphere to obtain a supported Ni metal nanoparticle catalyst.

[0014] Method 2: Sedimentation and Precipitation Method

[0015] Includes the following steps:

[0016] (1) Dissolve the Ni source and precipitant in deionized water, and add SiO2 support to the above solution. Stir the mixture at 90°C for 1.5-2.5 h.

[0017] (2) The mixture obtained in step (1) is filtered, the solid is dried, calcined in air, and then reduced in a hydrogen atmosphere to obtain a supported Ni metal nanoparticle catalyst.

[0018] In the above technical solution, further, in method one, the Ni source is selected from at least one of nickel nitrate, nickel acetate, and nickel iodide; the silicon oxide support is selected from at least one of FDU-12, SBA-15, and aerogel SiO2.

[0019] In the above technical solution, further, in method one, the drying temperature is 50-80℃ and the drying time is 12-48h; the calcination temperature is 400-800℃ and the calcination time is 3-8h; the reduction temperature is 200-600℃ and the reduction time is 1-4h.

[0020] In the above technical solution, further, in method two, the precipitant is urea and nitric acid; the molar concentration ratio of the Ni source, urea, and nitric acid is 21:1:1.

[0021] In the above technical solution, further, in method two, the drying temperature is 50-80℃ and the time is 12-48h; the calcination temperature is 400-800℃ and the calcination time is 3-8h; the reduction temperature is 200-600℃ and the reduction time is 1-4h.

[0022] In the above technical solution, the preparation method of the substituted benzyl-derived chiral modified molecule is as follows: using (1R,2R)-1-2-diphenylethylenediamine as the basic skeleton of the chiral modified molecule, using anhydrous N,N-dimethylformamide as the reaction solvent, adding 5.0 eq. of benzyl bromide or substituted benzyl bromide, adding 10.0 eq. of anhydrous potassium carbonate, using anhydrous DMF as the solvent, reacting at room temperature for 48 h, adding deionized water to dissolve excess potassium carbonate, extracting the aqueous phase with dichloromethane, and combining the organic phases, adding deionized water to backwash the organic phase, then washing the organic phase with saturated brine, drying with anhydrous sodium sulfate, evaporating the solvent to obtain the crude product, and finally purifying the crude product by column chromatography or recrystallization to obtain the target chiral modified molecule.

[0023] In the above technical solution, the substituted benzyl bromide further includes 4-nitrobenzyl bromide, 2-nitrobenzyl bromide, 4-trifluoromethylbenzyl bromide, and 4-methoxybenzyl bromide.

[0024] Another aspect of the present invention provides an application of the above-mentioned chiral nanoparticle catalytic system in the asymmetric Michael addition reaction between dimethyl malonate and β-nitrostyrene and its derivatives. Dimethyl malonate, β-nitrostyrene and its derivatives, supported Ni metal nanoparticle catalyst and benzyl-derived chiral modified molecules are added to a reaction tube, and toluene is used as the reaction solvent to carry out the reaction at 25-80°C for 12-24 hours.

[0025] In the above technical solution, the derivatives of β-nitrostyrene further include p-methylβ-nitrostyrene, o-methylβ-nitrostyrene, p-methoxyβ-nitrostyrene, p-N,N-dimethylβ-nitrostyrene, p-fluoroβ-nitrostyrene, p-chloroβ-nitrostyrene, p-bromoβ-nitrostyrene, p-nitroβ-nitrostyrene, 1-nitrohexene, and 1-nitropropylene.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. The supported Ni nanoparticle catalyst prepared by this invention has a small particle size and uniform distribution, and no obvious agglomeration phenomenon was observed.

[0028] 2. The catalytic system prepared by this invention is easy to separate and recycle after the reaction: the supported metal Ni nanoparticle catalyst can be recovered through simple filtration, washing and drying operations; the recovery of benzyl-modified chiral modified molecules can be achieved by simple acid treatment, water washing of the oil phase and subsequent alkalization operations.

[0029] 3. The method for preparing chiral modified molecules in this invention has strong universality, and a series of chiral modified molecules containing electron-withdrawing or electron-donating substituents can be obtained by the method described in this invention.

[0030] 4. The heterogeneous chiral metal nanoparticle catalytic system prepared in this invention exhibits higher reactivity and comparable enantioselectivity than the homogeneous Ni-diamine complex in the asymmetric addition reaction of dimethyl malonate with β-nitrostyrene compounds. This is because the benzyl-derived chiral modified molecule and the supported Ni nanoparticle catalyst can generate active species different from those in the homogeneous catalytic system during the reaction, altering the reaction pathway and significantly improving the reactivity of the heterogeneous chiral metal nanoparticle catalytic system.

[0031] 5. This catalyst has important application prospects in asymmetric carbon-carbon bond formation reactions, and constructing a multiphase chiral metal nanoparticle catalytic system provides an effective way to improve the performance of chiral catalytic reactions. Attached Figure Description

[0032] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0033] Figure 1 These are high-angle annular dark-field scanning transmission (HAADF-STEM) images of the catalysts obtained in Examples 1-3, where a, b, and c are Ni / SiO2-600H2, Ni / SiO2-400H2, and Ni / SiO2-200H2, respectively.

[0034] Figure 2 These are high-angle annular dark-field scanning transmission (HAADF-STEM) images of the catalysts obtained in Examples 1, 6, 7, and 8, where a, b, c, and d represent Ni / SiO2-600H2, Ni / SiO2-DP90-400℃Air, Ni / SiO2-DP90-550℃Air, and Ni / SiO2-DP90-700℃Air, respectively.

[0035] Figure 3 The images are transmission electron microscope (TEM) images of the catalysts in Comparative Examples 1-2, where a and b are Ni / Al2O3 and Ni / TiO2, respectively. Detailed Implementation

[0036] The following examples are provided to further illustrate the present invention, but they do not limit the scope of the invention as defined by the appended claims.

[0037] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially.

[0038] The analysis method in the following examples is as follows:

[0039] Conversion rate of the reaction: The substrate β-nitrostyrene in the reaction system was quantitatively analyzed by gas chromatography, with biphenyl as an internal standard. The gas chromatograph was equipped with an FID detector and an HP-5 capillary column. The conversion rate of the reaction was (n1-n2) / n1, where n1 and n2 represent the amount of added and remaining substrate β-nitrostyrene, respectively.

[0040] The yield of the reaction was determined using the internal standard method. 1 Quantification of the Michael addition product was performed using NMR, with mesitylene as an internal standard. After the reaction, column chromatography was used to separate the solid catalyst and chiral modified molecules by washing with a petroleum ether / ethyl acetate system as the eluent. A known mass of mesitylene was added to the collected solid, and quantification was performed by the area of ​​the characteristic signal peaks of mesitylene and the product, respectively. The yield of the reaction was n3 / n1, where n3 represents the amount of the chiral Michael addition product obtained by NMR quantification.

[0041] The ee value of chiral products is determined by high performance liquid chromatography (HPLC) equipped with a UV detector and an OD-H or OJ-H chiral column.

[0042] Example 1

[0043] Synthesis of Ni / SiO2-600H2 catalyst by strong electrostatic adsorption method.

[0044] Add 33.5 mg of Ni(NO3)2·(H2O)6 to a round-bottom flask, followed by 33 mL of deionized water; then add 2.5 mL of 28%-30% ammonia solution to adjust the pH to 11, thus generating [Ni(NH3)6]. 2+species; 553 mg of aerogel silica was added to the obtained solution; the mixture was stirred at room temperature for 4 h and then filtered, washed with deionized water and ethanol respectively, and dried at 60 °C for 48 h; the obtained solid was calcined in a muffle furnace at 500 °C for 48 h to obtain Ni / SiO2 precursor; then the Ni / SiO2 precursor was reduced at 600 °C for 2 h in H2 atmosphere, and the system was passivated by passing N2 after cooling to obtain Ni / SiO2-600H2.

[0045] Example 2

[0046] Synthesis of Ni / SiO2-400H2 catalyst by strong electrostatic adsorption method.

[0047] The preparation process in this embodiment is basically the same as that in Example 1, except that the reduction temperature of the Ni / SiO2 precursor in H2 atmosphere is different. It is reduced at 400℃ for 2 hours to obtain Ni / SiO2-400H2.

[0048] Example 3

[0049] Synthesis of Ni / SiO2-200H2 catalyst by strong electrostatic adsorption method.

[0050] The preparation process in this embodiment is basically the same as that in Example 1, except that the reduction temperature of the Ni / SiO2 precursor in H2 atmosphere is different. It is reduced at 200℃ for 2h to obtain Ni / SiO2-200H2.

[0051] Example 4

[0052] Ni / FDU-12-600H2 catalyst was synthesized by strong electrostatic adsorption. The preparation process in this example is basically the same as that in Example 1, except that FDU-12 was used as the silica support.

[0053] Example 5

[0054] Ni / SBA-15-600H2 catalyst was synthesized by strong electrostatic adsorption. The preparation process in this example is basically the same as that in Example 1, except that SBA-15 was used as the silica support.

[0055] Example 6

[0056] Ni / SiO2-DP90-400℃Air was prepared by deposition precipitation method.

[0057] 50 mL of an aqueous solution containing nickel nitrate hexahydrate, urea, and nitric acid was added to a round-bottom flask, with concentrations of 0.42 M, 0.02 M, and 0.02 M, respectively. 380 mg of silica support was added to the solution. The mixture was stirred at 90 °C for 90 min. The solid was then filtered, washed with water and ethanol, and dried at 60 °C for 48 h. The resulting solid was calcined in a muffle furnace at 400 °C for 48 h to obtain the Ni / SiO2-DP90 precursor. Subsequently, the Ni / SiO2-DP90 precursor was reduced at 600 °C for 2 h in a H2 atmosphere, and then passivated by passing N2 after cooling to obtain Ni / SiO2-DP90-400 °CAir.

[0058] Example 7

[0059] Ni / SiO2-DP90-550℃Air was prepared by deposition precipitation method.

[0060] The preparation process of this embodiment is basically the same as that of Example 6, except that the reduction temperature of the Ni / SiO2-DP90 precursor in air atmosphere is different. It is calcined at 550°C for 48 hours and then reduced in hydrogen atmosphere to obtain Ni / SiO2-DP90-550°CAir.

[0061] Example 8

[0062] Ni / SiO2-DP90-700℃Air was prepared by deposition precipitation method.

[0063] The preparation process of this embodiment is basically the same as that of Example 6, except that the reduction temperature of the Ni / SiO2-DP90 precursor in air atmosphere is different. It is calcined at 700°C for 48 hours and then reduced in hydrogen atmosphere to obtain Ni / SiO2-DP90-700°CAir.

[0064] Example 9

[0065] Ni / SiO2-DP90-800℃Air was prepared by deposition precipitation method.

[0066] The preparation process of this embodiment is basically the same as that of Example 6, except that the reduction temperature of the Ni / SiO2-DP90 precursor in air atmosphere is different. It is calcined at 800°C for 48 hours and then reduced in hydrogen atmosphere to obtain Ni / SiO2-DP90-800°CAir.

[0067] Example 10

[0068] Ni / SiO2-DP150-400℃Air was prepared by deposition precipitation method.

[0069] The preparation process of this embodiment is basically the same as that of Example 6, except that the stirring time of the mixed system at 90°C is 150 min.

[0070] Example 11

[0071] (1R,2R)-1-2-diphenylethylenediamine, derived from m-nitrobenzyl bromide, was prepared as a chiral modified molecule.

[0072] (1) Dissolve 2.0g of (1R,2R)-1-2-diphenylethylenediamine in 10mL of anhydrous N,N-dimethylformamide, add 10.2g of 2-nitrobenzyl bromide, add 13.0g of anhydrous potassium carbonate, and react at room temperature for 48h;

[0073] (2) Add deionized water to dissolve excess potassium carbonate, extract the aqueous phase with dichloromethane, combine the organic phases, add deionized water to backwash the organic phase, wash the organic phase with saturated brine, dry with anhydrous sodium sulfate, and spin dry the solvent at 40°C to obtain the crude product.

[0074] (3) Dissolve the crude product in 5.0 mL of dichloromethane, transfer the solution to a silica gel column prepared with 400 mesh silica gel powder, add a large amount of petroleum ether for washing, then add a mixed solution of petroleum ether, dichloromethane and diethyl ether in a volume ratio of 2:1:1 for washing, collect the target product, and evaporate it at 40 °C to obtain the purified crude product.

[0075] (4) Add 5.0 mL of dichloromethane to the purified crude product obtained in step (3) to completely dissolve the solid, then add 10.0 mL of diethyl ether. Continue to slowly add petroleum ether under reflux until the solid precipitates. Then add 1.0 mL of dichloromethane to the system to dissolve the precipitated solid again. Allow the mixed solution to cool at room temperature and collect the precipitated solid to obtain the high-purity target chiral modified molecule.

[0076] Comparative Example 1

[0077] Ni / Al2O3 catalyst prepared by impregnation method.

[0078] 1 g of Al2O3 and 2.0 wt% Ni(NO3)2·(H2O)6 (based on Ni) were added to a round-bottom flask, followed by 40 mL of deionized water. The mixture was stirred overnight at room temperature, and the deionized water in the mixture was evaporated and dried at 60 °C for 48 h. The resulting solid was calcined in a muffle furnace at 500 °C for 48 h to obtain the Ni / Al2O3 precursor. Subsequently, the Ni / Al2O3 precursor was reduced at 600 °C for 2 h in an H2 atmosphere, and the system was passivated by passing N2 after cooling to obtain Ni / Al2O3.

[0079] Comparative Example 2

[0080] Ni / TiO2 catalyst prepared by impregnation method.

[0081] The preparation process of this comparative example is basically the same as that of comparative example 1, except that the support is TiO2.

[0082] Application Example 1

[0083] Dimethyl malonate and β-nitrostyrene were used as raw materials for an asymmetric Michael addition reaction.

[0084] The reaction conditions were as follows: 1.5 mL toluene was used as the reaction solvent, 0.35 mmol dimethyl malonate and 0.25 mmol β-nitrostyrene were used as the reaction raw materials, 1 mol% Ni catalyst and 2 mol% (1R,2R)-1-2-diphenylethylenediamine derived from m-nitrobenzyl bromide prepared in Example 11 were added, the reaction temperature was 80 °C, the stirring rate was 1000 rpm, and the reaction time was 12 h.

[0085] After the reaction was completed, the temperature was lowered and the catalyst was filtered. The corresponding chiral Michael addition product was obtained by column chromatography.

[0086] Table 1 shows the evaluation results of the asymmetric Michael addition reaction between dimethyl malonate and β-nitrostyrene using the catalysts of Examples 1-3, 6-10 and Comparative Examples 1-2.

[0087] Table 1

[0088] Serial Number Group catalyst Conversion rate (%) Ee value (%) <![CDATA[TOF(h -1 )]]> 1 Example 1 <![CDATA[Ni / SiO2-600H2]]> 75 93 18.1 2 Example 2 <![CDATA[Ni / SiO2-400H2]]> 76 93 12.8 3 Example 3 <![CDATA[Ni / SiO2-200H2]]> 80 93 14.8 4 Example 6 <![CDATA[Ni / SiO2-DP90-400℃Air]]> 82 90 13.1 5 Example 7 <![CDATA[Ni / SiO2-DP90-550℃Air]]> 77 90 7.9 6 Example 8 <![CDATA[Ni / SiO2-DP90-700℃Air]]> 77 91 6 7 Example 9 <![CDATA[Ni / SiO2-DP90-800℃Air]]> 77 91 6 8 Example 10 <![CDATA[Ni / SiO2-DP150-400℃Air]]> 68 90 6 9 Comparative Example 1 <![CDATA[Ni / Al2O3]]> 23 81 1.9 10 Comparative Example 2 <![CDATA[Ni / TiO2]]> 18 94 1.5

[0089] The TOF values ​​in Table 1 were calculated from the reaction values ​​with a conversion rate of less than 30%.

[0090] Application Example 2

[0091] Asymmetric Michael addition reaction was carried out using dimethyl malonate, β-nitrostyrene and its derivatives as raw materials.

[0092] The reaction conditions were as follows: 1.5 mL toluene was used as the reaction solvent, 0.35 mmol dimethyl malonate and 0.25 mmol β-nitrostyrene were used as the reaction raw materials, 1 mol% of the catalyst prepared in Example 1 and 2 mol% of (1R,2R)-1-2-diphenylethylenediamine derived from m-nitrobenzyl bromide prepared in Example 11 were added, the reaction temperature was 80 °C, the stirring rate was 1000 rpm, and the reaction time was 21 h.

[0093] Table 2 shows the reaction evaluation results of the catalyst prepared in Example 1 in the asymmetric Michael addition reaction of dimethyl malonate and β-nitrostyrene and its derivatives.

[0094] Table 2

[0095]

[0096]

[0097] The results above show that the chiral nanoparticle catalytic system of this invention exhibits higher reactivity and a comparable Ee value compared to the homogeneous catalysts in the comparative example in the asymmetric Michael addition reaction of dimethyl malonate and β-nitrostyrene. Furthermore, the evaluation results in Table 1 indicate that the catalyst system using SiO2 support exhibits better reactivity than the catalyst systems using Al2O3, TiO2, and activated carbon as supports. This demonstrates that the heterogeneous chiral metal nanoparticle catalytic system of this invention can effectively improve the activity and selectivity of the asymmetric carbon-carbon bond formation reaction.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chiral nanoparticle catalytic system for asymmetric Michael addition reactions, characterized in that: The chiral nanoparticle catalytic system comprises a supported Ni metal nanoparticle catalyst with silica as the support and a substituted benzyl-derived chiral modified molecule; the substituted benzyl-derived chiral modified molecule is derived from benzyl bromide or substituted benzyl bromide. 1R, 2R )-1-2-diphenylethylenediamine; the substituted benzyl-derived chiral modified molecule is used to generate active species in situ during the reaction.

2. The chiral nanoparticle catalyst according to claim 1, characterized in that: In the catalytic system described, the content of the substituted benzyl-derived chiral modified molecule is 1-10 mol%, and the content of Ni metal is 1-20 wt%.

3. The chiral nanoparticle catalytic system according to claim 1 or 2, characterized in that: The supported Ni metal nanoparticle catalyst is prepared by one of the following two methods: Method 1: Strong electrostatic adsorption method Includes the following steps: (1) Dissolve the Ni source in deionized water, add ammonia to adjust the pH of the Ni source aqueous solution to 9-13, forming [Ni(NH3)6]. 2+ Species solution; (2) Add the silica support to the solution obtained in step (1) and stir at room temperature for 4-8 h to allow the [Ni(NH3)6] to settle. 2+ Species are adsorbed onto the silica support; (3) The mixture obtained in step (2) is filtered, the solid is dried, calcined in air, and then reduced in a hydrogen atmosphere to obtain a supported Ni metal nanoparticle catalyst. Method 2: Sedimentation and Precipitation Method Includes the following steps: (1) Dissolve the Ni source and precipitant in deionized water, and add SiO2 support to the above solution. Stir the mixture at 90°C for 1.5-2.5 h. (2) The mixture obtained in step (1) is filtered, the solid is dried, calcined in air, and then reduced in a hydrogen atmosphere to obtain a supported Ni metal nanoparticle catalyst.

4. The chiral nanoparticle catalytic system according to claim 3, characterized in that: In Method 1, the Ni source is selected from at least one of nickel nitrate, nickel acetate, and nickel iodide; the silicon oxide support is selected from at least one of FDU-12, SBA-15, and aerogel SiO2.

5. The chiral nanoparticle catalytic system according to claim 3, characterized in that: In Method 1, the drying temperature is 50-80℃ and the drying time is 12-48 h; the calcination temperature is 400-800℃ and the calcination time is 3-8 h; the reduction temperature is 200-600℃ and the reduction time is 1-4 h.

6. The chiral nanoparticle catalytic system according to claim 3, characterized in that: In Method 2, the precipitant is urea and nitric acid; the molar ratio of the Ni source, urea, and nitric acid is 21:1:

1.

7. The chiral nanoparticle catalytic system according to claim 3, characterized in that: In Method 2, the drying temperature is 50-80℃ and the time is 12-48 h; the calcination temperature is 400-800℃ and the calcination time is 3-8 h; the reduction temperature is 200-600℃ and the reduction time is 1-4 h.

8. The chiral nanoparticle catalytic system according to claim 1 or 2, characterized in that: The method for preparing the substituted benzyl-derived chiral modified molecule is as follows: using ( 1R , 2R Using 1,2-diphenylethylenediamine as the basic skeleton of the chiral modified molecule, anhydrous N,N-dimethylformamide was used as the reaction solvent. 5.0 eq. of benzyl bromide or substituted benzyl bromide was added, along with 10.0 eq. of anhydrous potassium carbonate. Anhydrous DMF was used as the solvent, and the reaction was carried out at room temperature for 48 h. Excess potassium carbonate was dissolved in deionized water, and the aqueous phase was extracted with dichloromethane. The organic phases were combined, backwashed with deionized water, washed with saturated brine, and dried with anhydrous sodium sulfate. The solvent was then evaporated to obtain the crude product. Finally, the crude product was purified by column chromatography or recrystallization to obtain the target chiral modified molecule.

9. The chiral nanoparticle catalytic system according to claim 8, characterized in that: The substituted benzyl bromide includes 4-nitrobenzyl bromide, 2-nitrobenzyl bromide, 4-trifluoromethylbenzyl bromide, and 4-methoxybenzyl bromide.

10. The application of the chiral nanoparticle catalytic system according to any one of claims 1-9 in the asymmetric Michael addition reaction between dimethyl malonate and β-nitrostyrene and its derivatives, characterized in that: Dimethyl malonate, β-nitrostyrene and its derivatives, supported Ni metal nanoparticle catalyst, and benzyl-derived chiral modified molecules were introduced into a reaction tube and reacted at 25-80℃ for 12-24 h using toluene as the reaction solvent.

Images