Pyrrolidinyl bifunctional catalyst bonded with photosensitizer as well as preparation method and application of pyrrolidinyl bifunctional catalyst

Abstract

The invention relates to a pyrrolidinyl bifunctional catalyst bonded with a photosensitizer as well as a preparation method and application of the pyrrolidinyl bifunctional catalyst. The catalyst has a structure of a nitrogen four-tooth chiral center and a thioxanthone photosensitive structural unit; according to the preparation method, a chiral tetradentate ligand and a photosensitizer are bonded through a chemical bond and then complexed with metal salt, and the metal complex catalyst with a chiral catalytic center and a photocatalytic center is obtained. The catalyst is applied to an asymmetric epoxidation reaction of chalcone, and an asymmetric epoxidation reaction process taking oxygen as an oxidizing agent is developed. The method provided by the invention is environment-friendly and has relatively high stereoselectivity.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, in particular to a pyrrolidyl bifunctional catalyst bonded to a photosensitizer and a preparation method thereof, and the catalyst is applied to catalyzing an asymmetric epoxidation reaction of chalcone. Background Art

[0002] Metal enzymes existing in nature, such as cytochrome P450 enzymes, use molecular oxygen as an oxidant in maintaining human life activities. Inspired by this, researchers have developed a series of biomimetic non-hormonal metal complex catalysts that simulate the local environment of enzymes to achieve catalytic conversion of specific substrates. This type of catalyst is mostly a complex formed by some chiral bidentate or multidentate nitrogen ligands and non-precious metals such as iron and manganese ions. Compared with traditional catalytic systems (such as salen catalysts), biomimetic non-hormonal metal catalysts have the advantage of a wide range of substrate applications. Under their catalysis, both functionalized olefins and non-functionalized olefins can undergo chiral epoxidation reactions with high enantioselectivity. In addition, the iron and manganese ions used in the central metal ions of this type of catalyst have the characteristics of wide sources, non-toxic or low toxicity, and environmental friendliness compared with precious metal ions.

[0003] However, under current conditions, this type of biomimetic catalytic system still has certain problems during use. For example, in the process of catalytic oxidation reaction, peroxides, hypochlorites, hypervalent iodine reagents, etc. are often used as oxidants. For example, Xiaohua Liu's research group used hypervalent iodine reagents as oxidants to achieve enantioselective epoxidation of cyclic and non-cyclic trisubstituted olefins (J.Am.Chem.Soc., 2023, 145, 15611-15618.), but the oxidant used is not only expensive, but also causes certain environmental pollution. Therefore, whether from an environmental protection perspective or an economic perspective, molecular oxygen is the most ideal oxidant. For example, Pan Xie (Synlett, 2024, dio: 10.1055 / a-2435-6142)'s research group used molecular oxygen as an oxidant to achieve the epoxidation of chalcone, but the epoxidation product did not have stereoselectivity.

[0004] Therefore, it is of great significance to combine photosensitizers with asymmetric catalytic centers through chemical bonds to obtain non-precious metal bifunctional catalysts. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that the photocatalytic center and the asymmetric catalytic center cannot be efficiently coordinated due to the long spatial distance, and to provide a pyrrolidine bifunctional catalyst bonded to a photosensitizer and a preparation method and application thereof. The catalyst has a structure of a nitrogen tetradentate chiral center and a thioxanthone photosensitive structural unit; in the preparation method, the chiral tetradentate ligand is bonded to the photosensitizer through a chemical bond, and then complexed with a metal salt to obtain a metal complex catalyst having a chiral catalytic center and a photocatalytic center; the catalyst is applied to the asymmetric epoxidation reaction of chalcone, and an asymmetric epoxidation reaction process using oxygen as an oxidant is developed. The present invention is environmentally friendly and has high stereoselectivity.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A pyrrolidine bifunctional catalyst bonded to a photosensitizer, the structural formula of the catalyst is as follows:

[0008]

[0009] Wherein, R = methyl, methoxy or -Cl; M = Mn or Fe; OTf = trifluoromethanesulfonate.

[0010] The method for preparing the pyrrolidyl bifunctional catalyst bonded to the photosensitizer comprises the following steps:

[0011] Step 1, adding pyrrolidine diamine with a nitrogen protecting group, 2-formaldehyde pyridine or a derivative thereof to a first solvent, reacting at 30-90° C. for 6-20 hours to generate an intermediate with a Schiff base structure; after cooling to room temperature, adding a first reducing agent to the system, reacting at 0-60° C. for 4-20 hours, evaporating the solvent under reduced pressure, extracting, drying and concentrating the solid residue to obtain a N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine derivative protected by a nitrogen protecting group, i.e., compound 2;

[0012] The molar ratio of the pyrrolidine diamine with a nitrogen protecting group to 2-formaldehyde pyridine is 1:1.8-4.0; the molar ratio of the pyrrolidine diamine with a nitrogen protecting group to the first reducing agent is 1:2-10;

[0013] The nitrogen protecting group in the pyrrolidinediamine with a nitrogen protecting group in the step (1) includes tert-butyloxycarbonyl, benzyloxycarbonyl, p-toluenesulfonyl, methoxybenzyl or benzyl;

[0014] The first solvent is methanol, ethanol or isopropanol; the first reducing agent is sodium borohydride, sodium cyanoborohydride, sodium acetylborohydride, potassium borohydride, lithium aluminum tetrahydride or hydrogen;

[0015] Step 2, dissolving compound 2 in a second solvent, adding glacial acetic acid and formaldehyde aqueous solution for reaction and condensation, reacting at 15-50° C. for 2-9 hours; after the reaction, adding a second reducing agent to the system for reduction for 8-20 hours, evaporating the solvent under reduced pressure, extracting, drying and concentrating the solid residue to obtain N,N'-dimethyl-N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine protected by a nitrogen protecting group, i.e., compound 3;

[0016] The molar ratio of the compound 2 to formaldehyde is 1:2-20, and the molar ratio of the compound 2 to the second reducing agent is 1:2-10;

[0017] The second solvent used in the (step 2) is acetonitrile, tetrahydrofuran, methanol, ethanol, isopropanol or dichloromethane, and the second reducing agent is sodium borohydride, sodium cyanoborohydride, sodium acetylborohydride, potassium borohydride, lithium aluminum tetrahydride or hydrogen.

[0018] Step 3, dissolving compound 3 in a third solvent, adding acid dropwise to the system, heating to reflux for 1-10 hours to remove the nitrogen protecting group, then cooling to room temperature and removing the solvent under reduced pressure, extracting, drying and concentrating the solid residue to obtain an unprotected N,N'-dimethyl-N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine derivative, and then reacting with 3-acylchloridothioxanthone in a fourth solvent at room temperature in the presence of an acid binding agent, and then separating and purifying to obtain a tetradentate ligand bonded to a photosensitizer, i.e., compound 4;

[0019] The molar ratio of compound three to acid is 1:0.1-4.0; the molar ratio of compound three to 3-acylchloridothioxanthone is 1:0.6-2.0; the molar ratio of acid-binding agent to compound three is 1:2-8;

[0020] The acid in the step (3) is trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, hydrobromic acid, hydrochloric acid or sulfuric acid;

[0021] The third solvent is one of dichloromethane, chloroform, and dichloroethane; the acid binding agent is one of an organic base such as triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, or an inorganic base such as sodium carbonate, potassium carbonate, and sodium acetate; the fourth solvent is one of acetonitrile, tetrahydrofuran, methanol, ethanol, dichloromethane, and dichloroethane.

[0022] Step 4, dissolving compound 4 in a fifth solvent, adding a metal salt suspension dropwise thereto under the protection of an inert gas, reacting at 15-50° C. in the dark for 4-18 hours, and recrystallizing after the reaction to obtain a bifunctional catalyst complex;

[0023] Wherein, the molar ratio of compound 4 to metal salt is 1:0.8-4;

[0024] In the step (4), the metal salt is Mn(OSO 2 CF 3 ) 2 or Fe(OSO 2 CF 3 ) 2 2CH 3 CN, and the fifth solvent is one of acetonitrile, tetrahydrofuran, methanol, ethanol, dichloromethane, and dichloroethane.

[0025] The application of the pyrrolidine bifunctional catalyst bonded to the photosensitizer is used to catalyze the asymmetric epoxidation reaction of chalcone and its derivatives to prepare epoxides with high optical purity.

[0026] The method comprises the following steps: sequentially adding a catalyst, chalcone or a chalcone derivative, a co-catalyst, a sacrificial reducing agent and a solvent into a reaction tube, then replacing and filling with oxygen at 1 to 3 atmospheres, stirring and reacting for 2 to 20 hours under the conditions of -50°C to 0°C and visible light illumination to obtain an epoxide;

[0027] Among them, 10-15 mg of catalyst, 41.6 mg of chalcone or chalcone derivative, 20 -40 microliters of co-catalyst, and 60-100 mg of sacrificial reducing agent are added to 1-4 mL of solvent;

[0028] The co-catalyst is specifically 2-ethylhexanoic acid or acetic acid or pivalic acid;

[0029] The sacrificial reducing agent is specifically 2-ethylhexanal or acetaldehyde or pivalaldehyde; the solvent is acetonitrile;

[0030] The chalcone or chalcone derivative is: 1,3-diphenyl-2-propenone, 3-phenyl-1-(m-tolyl)prop-2-ene-1-one or 3-phenyl-1-(o-tolyl)prop-2-ene-1-one;

[0031] The corresponding epoxy compound obtained is 1,3-diphenyl-2,3-epoxy-1-propanone, 3-phenyl-1-(m-tolyl)propane-2,3-epoxy-1-one or 3-phenyl-1-(o-tolyl)propane-2,3-epoxy-1-one;

[0032] The essential features of the present invention are:

[0033] At present, bionic non-hormonal metal complex catalysts are mostly complexes formed by some multidentate nitrogen ligands and non-precious metals; and in the process of selecting oxidants, most of them use peroxides, hypochlorites, high-valent iodine reagents, etc. as oxidants for oxidation reactions. Such oxidants are not only expensive, but also pollute the environment.

[0034] The present invention replaces the traditional oxidant with molecular oxygen, and bonds the chiral tetradentate ligand to the photosensitizer through chemical bonds, which are then complexed with metal salts to obtain a metal complex catalyst with a chiral catalytic center and a photocatalytic center, thereby greatly improving the catalytic efficiency.

[0035] The beneficial effects of the present invention are:

[0036] The present invention proposes and synthesizes a novel catalyst for a chiral asymmetrically bonded photosensitizer for the first time, which brings the relative spatial position of the chiral catalytic center and the photosensitizer center closer and fixed, so that the oxygen molecules can efficiently migrate to the asymmetric catalytic reaction center after the photosensitizer unit is activated, avoiding the quenching of the active substrate that may be caused by long-distance migration. The catalyst is applied to the asymmetric epoxidation reaction of chalcone, using green and cheap oxygen instead of traditional peroxides, hypochlorites, high-valent iodine reagents, etc. as the oxidant of the epoxidation reaction, avoiding pollution while reducing the reaction cost, and the yield of the epoxidation product is as high as 88%, and the enantiomeric excess is 75%. DETAILED DESCRIPTION

[0037] The following will be combined with specific embodiments to clearly and completely describe the technical solutions in the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0038] The reaction formula of the catalyst of the present invention is as follows:

[0039]

[0040] Synthesis of Boc-protected N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine:

[0041]

[0042] As shown in the above formula, 2.8 mmol of chiral pyrrolidine diamine with Boc (tert-butylcarbonyl) protection is dissolved in 50.0 mL of methanol in a container equipped with a stirring, heating, temperature control and reflux device, and then 5.6 mmol of 2-formaldehyde pyridine is added dropwise thereto. After the addition is complete, the mixture is heated to 65°C and the system is refluxed for 12 hours. After the reaction is completed, the mixture is cooled to room temperature and 22.4 mmol of solid NaBH is slowly added thereto in batches. 4During the addition, bubbles appeared in the system. After the addition was completed, the reaction was continued to stir at room temperature for 12 hours. After the reaction was completed, the solvent was evaporated under reduced pressure and 200 mL of dichloromethane was added to the residue to dissolve. The organic phase was washed with 50 mL of saturated brine and dried over anhydrous sodium sulfate. The anhydrous sodium sulfate was then filtered off and the filtrate was concentrated in vacuo to obtain compound II, namely Boc-protected N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine.

[0043] Embodiment 2:

[0044] Synthesis of Boc-protected N,N'-dimethyl-N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine:

[0045]

[0046] As shown in the above formula, 2.8 mmol of compound 2 was dissolved in 20.0 mL of acetonitrile in a container equipped with a stirring, heating, temperature control and reflux device, and then 2.0 mL of glacial acetic acid and 28 mmol of 37% formaldehyde aqueous solution (containing 10.36 mmol of formaldehyde) were added thereto in sequence. The resulting mixture was stirred at room temperature for two hours, and then 14 mmol of NaBH was slowly added thereto. 4 Solid, during the addition process, it should be noted that the system is violently exothermic and a large number of bubbles are generated. After the addition is completed, the mixture is stirred and reacted at room temperature for 12 hours, and then 50.0mL of deionized water is added to quench the reaction. The mixture is extracted three times with 50.0mL of dichloromethane, the organic phases are combined, dried over anhydrous sodium sulfate, filtered and the solvent is removed in vacuo, and the residue is separated by silica gel column chromatography to obtain compound three, that is, Boc-protected N,N'-dimethyl-N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine, the eluent ratio used is v:v ethyl acetate: petroleum ether = 1:1, and 5% volume fraction of triethylamine is added.

[0047] Example 3: Synthesis of a pyrrolidine bifunctional catalyst ligand bonded to a photosensitizer:

[0048]

[0049] As shown in the above formula, 10.0 mL of dichloromethane is used to dissolve 2.8 mmol of the methylated product in a container equipped with a stirring, heating, temperature control and reflux device, and then 39.2 mmol of trifluoroacetic acid is added dropwise thereto under stirring. After the addition is complete, the reaction system is heated to 40°C for reflux reaction for 5 hours, and then cooled to room temperature, and the solvent is removed under vacuum conditions, and the residue is adjusted to pH 11 using a 2N KOH aqueous solution. The mixture is extracted three times with 30.0 mL of dichloromethane, the organic phases are combined, dried over anhydrous sodium sulfate, and concentrated in vacuo to obtain 2.8 mmol of a crude product, 10 ml of dichloromethane is used to dissolve the above crude product, and then 2.8 mmol of 3-acyl chloride thioxanthone and 22.4 mmol of triethylamine are added thereto, and the reaction is stirred at room temperature for 24 hours. After the reaction is completed, the solvent is removed under vacuum conditions, and the remaining residue is separated using silica gel column chromatography to obtain compound four, i.e., a pyrrolidine bifunctional catalyst ligand for synthesizing a bonded photosensitizer. The eluent ratio used is v:v ethyl acetate: petroleum ether = 1:1, and triethylamine is added at a volume fraction of 5%.

[0050] Example 4: Synthesis of a pyrrolidine bifunctional catalyst with an iron-centered photosensitizer

[0051] In a container equipped with a stirring function, 1.0 mL of anhydrous THF was used to dissolve 0.5 mmol of the compound 4 obtained in Example 3, and then 0.5 mmol of Fe(CF 3 SO 3 ) 2 (CH 3 CN) 2 A suspension of anhydrous THF (1 mL) was added dropwise to the above system. After the addition was completed, the reaction was stirred at room temperature for 48 h. After the reaction was completed, the solvent was removed under reduced pressure, and the residue was recrystallized using an acetonitrile / n-hexane system to obtain the catalyst.

[0052] Example 5: Synthesis of a pyrrolidine bifunctional catalyst for a manganese-centered photosensitizer

[0053] In a stirring vessel, 1.0 mL of anhydrous THF was used to dissolve 0.5 mmol of the ligand obtained in Example 3, and then 0.5 mmol of Mn(CF 3 SO 3 ) 2 (CH 3 CN) 2 A suspension of anhydrous THF (1 mL) was added dropwise to the above system. After the addition was completed, the reaction was stirred at room temperature for 48 h. After the reaction was completed, the solvent was removed under reduced pressure, and the residue was recrystallized using an acetonitrile / n-hexane system to obtain the catalyst.

[0054] Example 6: Synthesis of a chlorine-substituted pyrrolidine bifunctional ligand for photosensitizer bonding

[0055] According to the steps of Example 1-3, the 2-formaldehyde pyridine in Example 1 was replaced by 4-chloropyridine-2-carboxaldehyde to obtain the target product compound VII, which is a chlorine atom-substituted pyrrolidine bifunctional ligand of the photosensitizer bonded to the target product compound VII, and its structure is shown below.

[0056]

[0057] Example 7: 12.5 mg of catalyst, 41.6 mg of chalcone, 0.5 mL of anhydrous acetonitrile were added to a dry 20 mL micro reaction tube in sequence, and 30 microliters of 2-ethylhexanoic acid was added thereto, and 1 atmosphere of oxygen was replaced and then cooled to -40°C in a cold trap, and a photo-irradiation reaction was carried out at a distance of 10 cm from a xenon lamp light source (wavelength range 420 nm to 1000 nm). 80 mg of 2-ethylhexanal was dissolved in 1.5 mL of acetonitrile, and then the aldehyde solution was injected into the reaction system within 3 hours using a micro injection pump, and the reaction was continued to stir for 2 hours after the injection was completed; after the reaction was completed, the reaction solution was chromatographed using a silica gel column, and the eluent was ethyl acetate: petroleum ether = 1:50, and the epoxidation product was separated, and its yield was 88%, and the ee value was as high as 75%.

[0058] Compound 4 NMR data:

[0059] 1 H NMR (400 MHz, CDCl 3 )δ8.64(t,J=8.9Hz,2H),8.56-8.48(m,2H),7.71(s,1H),7.67-7.59(m,4H),7.54-7.50(m,2H),7.46(d,J=7.7Hz,1H),7.36(d,J=7.6Hz,1H). 7.18-7.12(m,2H),3.99-3.19(m,2H),3.88-3.82(m,2H),3.77-3.73(m ,2H),3.62-3.59(m,2H),3.53-3.43(m,2H).2.36(s,3H),2.27(s,3H).

[0060] 13 C NMR (101 MHz, CDCl 3)δ179.42,168.05,159.08,158.86,149.10,139.67,137.75,137.09,136.65,132.59,130.12,129.93,129.1 6,126.65,126.08,124.95,124.50,122.85,122.20,64.52,63.24,60.98,60.82,48.77,45.48,38.25,38.20.

[0061] Compound 7 NMR data

[0062] 1 H NMR (400 MHz, CDCl 3 ), δ8.68-8.62(m,2H),8.46-8.38(m,2H),7.73(s,1H),7.71-7.59(m,2H),7.57-7.51(m,3H),7.42(s,1H),7.21-7.16(m,2H) ,4.00-3.96(m,2H),3.91-3.83(m,2H),3.78-3.74,(m,2H),3.65-3.62,(m,2H),3.60-3.53(m,2H),2.40(s,3H),2.30(s,3H).

[0063] 13 C NMR (101 MHz, CDCl 3 )δ179.40,168.09,160.93,160.74,150.09,144.91,139.52,137.81,137.07,132.63,130.18,130.00,129.94,12 9.17,126.69,126.09,124.99,124.47,123.00,122.71,64.62,63.29,60.47,60.34,48.62,45.24,38.48,38.42.

[0064] 1,3-Diphenyl-2,3-epoxy-1-propanone NMR data

[0065] 1 H NMR (400 MHz, CDCl 3)δ8.07-8.05(m,2H),7.69-7.65(m,1H),7.56-7.52(m,2H),7.48-7.41(m,5H),4.35(d,J=1.3Hz,1H),4.13(d,J=1.3Hz,1H).

[0066] Matters not covered by the present invention are known technologies.

Claims

1. A pyrrolidyl bifunctional catalyst bonded to a photosensitizer, characterized in that the catalyst has the following structural formula: in, R = methyl, methoxy or -Cl; M = Mn or Fe.

2. The method for preparing the pyrrolidino-based bifunctional catalyst bonded to a photosensitizer as claimed in claim 1, characterized in that: The following steps are involved: Step 1, adding pyrrolidine diamine with a nitrogen protecting group, 2-formaldehyde pyridine or a derivative thereof to a first solvent, reacting at 30-90° C. for 6-20 hours to generate an intermediate with a Schiff base structure; after cooling to room temperature, adding a first reducing agent to the system, reacting at 0-60° C. for 4-20 hours, evaporating the solvent under reduced pressure, extracting, drying and concentrating the solid residue to obtain a N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine derivative protected by a nitrogen protecting group, i.e., compound 2; The molar ratio of the pyrrolidine diamine with a nitrogen protecting group to 2-formaldehyde pyridine is 1:1.8-4.0; the molar ratio of the pyrrolidine diamine with a nitrogen protecting group to the first reducing agent is 1:2-10; The nitrogen protecting group in the pyrrolidinediamine having a nitrogen protecting group includes tert-butyloxycarbonyl, benzyloxycarbonyl, p-toluenesulfonyl, methoxybenzyl or benzyl; The first reducing agent is sodium borohydride, sodium cyanoborohydride, sodium acetylborohydride, potassium borohydride, lithium aluminum tetrahydride or hydrogen; Step 2, dissolving compound 2 in a second solvent, adding glacial acetic acid and formaldehyde aqueous solution for reaction and condensation, reacting at 15-50° C. for 2-9 hours; after the reaction, adding a second reducing agent to the system for reduction for 8-20 hours, evaporating the solvent under reduced pressure, extracting, drying and concentrating the solid residue to obtain N,N'-dimethyl-N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine protected by a nitrogen protecting group, i.e., compound 3; The molar ratio of the compound 2 to formaldehyde is 1:2-20, and the molar ratio of the compound 2 to the second reducing agent is 1:2-10; The second reducing agent is sodium borohydride, sodium cyanoborohydride, sodium acetylborohydride, potassium borohydride, lithium aluminum tetrahydride or hydrogen; Step 3, dissolving compound 3 in a third solvent, adding acid dropwise to the system, heating to reflux for 1-10 hours to remove the nitrogen protecting group, then cooling to room temperature and removing the solvent under reduced pressure, extracting, drying and concentrating the solid residue to obtain an unprotected N,N'-dimethyl-N,N'-bis(pyridine-2-methylene)pyrrolidine-3,4-diamine derivative, and then reacting with 3-acylchloridothioxanthone in a fourth solvent at room temperature in the presence of an acid binding agent, and then separating and purifying to obtain a tetradentate ligand bonded to a photosensitizer, i.e., compound 4; The molar ratio of compound three to acid is 1:0.1-4.0; the molar ratio of compound three to 3-acylchloridothioxanthone is 1:0.6-2.0; the molar ratio of acid-binding agent to compound three is 1:2-8; The acid-binding agent is an organic base or an inorganic base; Step 4, dissolving compound 4 in a fifth solvent, adding a metal salt suspension dropwise thereto under the protection of an inert gas, reacting at 15-50° C. in the dark for 4-18 hours, and recrystallizing after the reaction to obtain a bifunctional catalyst complex; Wherein, the molar ratio of compound 4 to metal salt is 1:0.8-4; The metal salt is Mn(OSO2CF3)2 or Fe(OSO2CF3)2·2CH3CN.

3. The method for preparing the pyrrolidino-based bifunctional catalyst bonded to a photosensitizer as claimed in claim 2, characterized in that: In the step 1, the first solvent is methanol, ethanol or isopropanol; The second solvent used in step 2 is acetonitrile, tetrahydrofuran, methanol, ethanol, isopropanol or dichloromethane. In the step 3, the third solvent is dichloromethane, chloroform or dichloroethane; The fourth solvent is acetonitrile, tetrahydrofuran, methanol, ethanol, dichloromethane or dichloroethane; In the step 4, the fifth solvent is acetonitrile, tetrahydrofuran, methanol, ethanol, dichloromethane or dichloroethane.

4. The method for preparing the pyrrolidino-based bifunctional catalyst bonded to a photosensitizer as claimed in claim 2, characterized in that: In step 3, the acid is trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, hydrobromic acid, hydrochloric acid or sulfuric acid; The acid binding agent is triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, sodium carbonate, potassium carbonate or sodium acetate.

5. The use of the pyrrolidyl bifunctional catalyst bonded to the photosensitizer as claimed in claim 1, characterized in that: Used to catalyze the asymmetric epoxidation of chalcone and its derivatives to prepare epoxides with high optical purity.

6. The use of a pyrrolidyl bifunctional catalyst bonded to a photosensitizer as claimed in claim 5, characterized in that: The following steps are involved: Adding a catalyst, chalcone or a chalcone derivative, a co-catalyst, a sacrificial reducing agent and a solvent into a reaction tube in sequence, then replacing and filling with oxygen at 1 to 3 atmospheres, stirring and reacting for 2 to 20 hours under -50°C to 0°C and visible light illumination to obtain an epoxide; Among them, 10-15 mg of catalyst, 41.6 mg of chalcone or chalcone derivative, 20-40 μL of co-catalyst, and 60-100 mg of sacrificial reducing agent are added to 1-4 mL of solvent; The co-catalyst is specifically 2-ethylhexanoic acid or acetic acid or pivalic acid; The sacrificial reducing agent is specifically 2-ethylhexanal or acetaldehyde or pivalaldehyde; The solvent is acetonitrile; The chalcone or chalcone derivative is: 1,3-diphenyl-2-propenone, 3-phenyl-1-(m-tolyl)prop-2-ene-1-one or 3-phenyl-1-(o-tolyl)prop-2-ene-1-one; The corresponding epoxy compound obtained is 1,3-diphenyl-2,3-epoxy-1-propanone, 3-phenyl-1-(m-tolyl)propane-2,3-epoxy-1-one or 3-phenyl-1-(o-tolyl)propane-2,3-epoxy-1-one.

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