Refining method of Apremilast intermediate

文档序号：795633 发布日期：2021-04-13 浏览：46次中文

阅读说明：本技术 阿普斯特类中间体的精制方法 (Refining method of Apremilast intermediate ) 是由李彦雄徐亮蒙发明于永海冯杰于 2020-12-23 设计创作，主要内容包括：本发明涉及阿普斯特类中间体的精制方法,包括以下步骤：提供式(I)所示中间体的粗品；采用精制溶剂对式(I)所示中间体的粗品进行精制,制得式(I)所示中间体的精制品；其中,精制溶剂为甲基异丁基酮、乙腈和丁酮中至少一种；R-1、R-2和R-3各自独立地为C-(1-16)烷基、3-8元环烷基、5-10元芳基或5-10元杂芳基。通过采用上述精制溶剂对式(I)所示中间体的粗品进行纯化处理,有效地提高了式(I)所示中间体的纯度,能够在保持产物具有较高的产率的基础上,将工艺杂质的残留量控制在0.1％以下。(The invention relates to a refining method of an apremilast intermediate, which comprises the following steps: providing a crude product of an intermediate shown in a formula (I); refining the crude product of the intermediate shown in the formula (I) by adopting a refining solvent to prepare a refined product of the intermediate shown in the formula (I); wherein the refined solvent is at least one of methyl isobutyl ketone, acetonitrile and butanone; R 1 、R 2 and R 3 Each independently is C 1‑16 Alkyl, 3-8 membered cycloalkyl, 5-10 membered aryl or 5-10 membered heteroaryl. Purifying the crude product of the intermediate shown in the formula (I) by adopting the refined solventThe treatment effectively improves the purity of the intermediate shown in the formula (I), and can control the residual amount of process impurities to be below 0.1 percent on the basis of keeping higher yield of the product.)

1. A method for purifying an intermediate represented by the formula (I), characterized by comprising the steps of:

providing a crude product of an intermediate shown in a formula (I);

refining the crude product of the intermediate shown in the formula (I) by adopting a refining solvent to prepare a refined product of the intermediate shown in the formula (I);

wherein the refined solvent is at least one of methyl isobutyl ketone, acetonitrile and butanone;

R₁、R₂and R₃Each independently is C_1-16Alkyl, 3-8 membered cycloalkyl, 5-10 membered aryl or 5-10 membered heteroaryl.

2. The purification process according to claim 1, wherein R is₁Is methyl, R₂Is ethyl, R₃Is methyl.

3. The purification method according to claim 1, wherein the purification solvent is a mixed solvent composed of methyl isobutyl ketone and acetonitrile in a volume ratio of 1:1 to 10: 1.

4. The purification process according to claim 3, wherein the ratio by volume of the methyl isobutyl ketone to the acetonitrile is 3:1 to 6: 1; and (3) refining 1g of the crude product of the intermediate shown in the formula (I) by using 5-10mL of the refining solvent.

5. The purification process according to claim 1, wherein in the purification step, the crude product of the intermediate represented by the formula (I) is recrystallized by cooling crystallization using the purification solvent.

6. The refining process of claim 5, wherein the step of refining comprises the steps of:

mixing the crude product of the intermediate shown in the formula (I) with a refined solvent, and dissolving at the temperature of 50-80 ℃;

cooling to 0-10 deg.C, standing, separating crystal, collecting crystal, and drying to obtain refined product of intermediate shown in formula (I).

7. The refining method of any one of claims 1 to 6, wherein the crude product of the intermediate represented by formula (I) contains 0.01 to 10% by mass of impurities.

8. The purification process as claimed in any one of claims 1 to 6, wherein the crude intermediate represented by the formula (I) contains at least one impurity of the following structure:

9. the purification method according to any one of claims 1 to 6, wherein the step of providing a crude product of the intermediate represented by the formula (I) comprises the steps of:

providing a compound with a structure shown in a formula (II);

and (3) carrying out asymmetric catalytic hydrogenation on the compound with the structure shown in the formula (II) to obtain a crude product of the intermediate shown in the formula (I).

10. The purification method according to claim 9, wherein the catalyst used in the asymmetric catalytic hydrogenation reaction has a structure represented by the following formula (a):

r is a high molecular polymer;

m is a transition metal;

x, Y are each independently a halogen radical;

represents a bisphosphine ligand;

R₄is H or C_1-8An alkyl group.

Technical Field

The invention relates to the technical field of pharmaceutical chemistry, in particular to a refining method of an apremilast intermediate.

Background

Apremilast (Apremilast), chemically known as (S) -2- [1- (3-ethoxy-4-methoxyphenyl) -2-methylsulfonylethyl ] -4-acetylaminoisoindoline-1, 3-dione, is a selective PDE4 inhibitor developed by Celgene corporation, marketed as an oral drug for the treatment of psoriatic arthritis by FDA approval in U.S. 3 months 2014 and approved by FDA in U.S. 9 months 2014 for the treatment of moderate to severe psoriasis (also known as plaque psoriasis), commercially known as Otezla. Apremilast, as an oral small molecule phosphodiesterase 4(PDE4) inhibitor, can selectively inhibit PDE4, can specifically act on cyclic adenosine monophosphate (cAMP), and PDE4 inhibition causes the increase of intracellular cAMP level and generates anti-inflammatory activity by preventing rheumatoid synovial cells from secreting tumor necrosis factor alpha (TNF-alpha), and is mainly clinically used for treating psoriatic arthritis and plaque psoriasis.

The traditional apremilast synthetic route is as follows:

the method comprises the steps of firstly synthesizing a chiral amine intermediate and an anhydride intermediate, and then aminating the chiral amine intermediate and the anhydride intermediate to obtain the aplite. Therefore, the synthesis of the chiral amine intermediate (S) -2- [1- (3-ethoxy-4-methoxyphenyl) ] -1-methylsulfonyl-2-ethylamine is the key for preparing apremilast, and the advantages and disadvantages of the production process directly influence the synthesis cost and chiral purity of the medicine. Therefore, I have studied and redesigned the synthetic route, and adopted the following synthetic method:

the method utilizes BIMAH series catalysts to carry out asymmetric catalytic hydrogenation on ketone to construct chiral secondary alcohol, and then converts the chiral secondary alcohol into chiral secondary amine so as to achieve the purpose of constructing the chiral amine, so that chiral resolution is avoided, the chirality of amino constructed by various complex chiral reagents is also avoided, and the method has the advantages of simple synthetic route, stable reaction process, environmental protection, economy, low cost and the like.

However, in the above method, the compound 2 is used to prepare the compound 1 to construct a chiral center, which has a decisive effect on the whole reaction route, so that the purity requirement of the compound 2 is high. However, even if a catalyst with higher catalytic efficiency is adopted in the step, the conversion rate of the product is only about 96%, the purity of the crude product is only 93%, the residual quantity of the intermediate compound 1 still reaches about 2% through a conventional impurity removal mode and a large amount of purification processes, and the quality requirement of 'single impurity residual less than 0.1% of' of a high-grade intermediate cannot be met.

Disclosure of Invention

Based on the above, a purification method of the apremilast intermediate is needed, and the purity of the product obtained by the purification method reaches more than 99.7%, and the limited amount of impurities is less than 0.1%.

A method for purifying an intermediate represented by formula (I), comprising the steps of:

providing a crude product of an intermediate shown in a formula (I);

refining the crude product of the intermediate shown in the formula (I) by using a refining solvent to prepare a refined product of the intermediate shown in the formula (I);

wherein the refined solvent is at least one of methyl isobutyl ketone, acetonitrile and butanone;

R₁、R₂and R₃Each independently is C_1-16Alkyl, 3-8 membered cycloalkyl, 5-10 membered aryl or 5-10 membered heteroaryl.

In one embodiment, R₁Is methyl, R₂Is ethyl, R₃Is methyl.

In one embodiment, the refined solvent is a mixed solvent composed of methyl isobutyl ketone and acetonitrile in a volume ratio of 1: 1-10: 1.

In one embodiment, the volume ratio of the methyl isobutyl ketone to the acetonitrile is 3: 1-6: 1; and (3) refining 1g of the crude product of the intermediate shown in the formula (I) by using 5-10mL of the refining solvent.

In one embodiment, in the purification step, the intermediate represented by formula (I) is recrystallized by cooling crystallization using the purification solvent.

In one embodiment, the refining step comprises the steps of:

mixing the intermediate shown in the formula (I) with a refined solvent, and dissolving at 50-80 ℃;

cooling to 0-10 deg.C, standing, separating crystal, collecting crystal, and drying to obtain refined product of intermediate shown in formula (I).

In one embodiment, the mass percentage of impurities in the crude product of the intermediate shown in the formula (I) is 0.01-10%.

In one embodiment, the crude intermediate of formula (I) comprises at least one impurity of the following structure:

in one embodiment, the step of providing the intermediate represented by formula (I) comprises the following steps:

providing a compound with a structure shown in a formula (II);

and (3) carrying out asymmetric catalytic hydrogenation on the compound with the structure shown in the formula (II) to obtain a crude product of the intermediate shown in the formula (I).

In one embodiment, the catalyst used in the asymmetric catalytic hydrogenation reaction has a structure represented by the following formula (a):

r is a high molecular polymer;

m is a transition metal;

x, Y are each independently a halogen radical;

represents a bisphosphine ligand;

R₄is H or C_1-8An alkyl group.

Has the advantages that:

the skilled person in the present application finds in the study: the main impurities affecting the purity of the final product are enantiomers of the compound shown in the formula (II) and/or the intermediate shown in the formula (I), and the enantiomers are similar to the intermediate shown in the formula (I) in properties, so that the two are difficult to separate by the traditional method, and the purity of the final product cannot meet the requirement. Based on this, the present inventors have found through extensive research that the purification treatment of the crude product of the intermediate represented by formula (I) by using the above refined solvent and using the similar phase dissolution principle can effectively improve the purity of the intermediate represented by formula (I), and the refined solvent of the present invention can control the residual amount of process impurities to be less than 0.1% on the basis of ensuring a higher yield of the product. In addition, the refining method is simple in operation, does not need special instruments or special operation skills, and is particularly suitable for industrial production application.

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Term(s) for

Unless otherwise stated or contradicted, terms or phrases used herein have the following meanings:

the term "alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing the term, e.g., "C₁～C₁₆The alkyl group means an alkyl group having 1 to 16 carbon atoms. Suitable examples include, but are not limited to: methyl (Me, -CH)₃) Ethyl (Et-CH)₂CH₃) 1-propyl (n-Pr, n-propyl, -CH)₂CH₂CH₃) 2-propyl (i-Pr, i-propyl, -CH (CH)₃)₂) 1-butyl (n-Bu, n-butyl, -CH)₂CH₂CH₂CH₃) 2-methyl-1-propyl (i-Bu, i-butyl, -CH)₂CH(CH₃)₂) 2-butyl (s-Bu, s-butyl, -CH (CH)₃)CH₂CH₃) 2-methyl-2-propyl (t-Bu, t-butyl, -C (CH)₃)₃) 1-pentyl (n-pentyl, -CH)₂CH₂CH₂CH₂CH₃) 2-pentyl (-CH (CH3) CH2CH2CH3), 3-pentyl (-CH (CH)₂CH₃)₂) 2-methyl-2-butyl (-C (CH)₃)₂CH₂CH₃) 3-methyl-2-butyl (-CH (CH)₃)CH(CH₃)₂) 3-methyl-1-butyl (-CH)₂CH₂CH(CH₃)₂) 2-methyl-1-butyl (-CH)₂CH(CH₃)CH₂CH₃) 1-hexyl (-CH)₂CH₂CH₂CH₂CH₂CH₃) 2-hexyl (-CH (CH)₃)CH₂CH₂CH₂CH₃) 3-hexyl (-CH (CH)₂CH₃)(CH₂CH₂CH₃) 2-methyl-2-pentyl (-C (CH))₃)₂CH₂CH₂CH₃) 3-methyl-2-pentyl (-CH (CH)₃)CH(CH₃)CH₂CH₃) 4-methyl-2-pentyl (-CH (CH)₃)CH₂CH(CH₃)₂) 3-methyl-3-pentyl (-C (CH)₃)(CH₂CH₃)₂) 2-methyl-3-pentyl (-CH (CH)₂CH₃)CH(CH₃)₂) 2, 3-dimethyl-2-butyl (-C (CH)₃)₂CH(CH₃)₂) 3, 3-dimethyl-2-butyl (-CH (CH)₃)C(CH₃)₃And octyl (- (CH)₂)₇CH₃)。

The term "cycloalkyl" refers to a non-aromatic hydrocarbon containing ring carbon atoms and may be a monocycloalkyl, or spirocycloalkyl, or bridged cycloalkyl. Phrases encompassing this term, such as "3-8 membered cycloalkyl" refer to cycloalkyl groups containing 3 to 8 carbon atoms. Suitable examples include, but are not limited to: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. In addition, "cycloalkyl" may also contain one or more double bonds, and representative examples of cycloalkyl groups containing a double bond include cyclopentenyl, cyclohexenyl, cyclohexadienyl, and cyclobutadienyl.

"aryl" refers to an aromatic hydrocarbon group derived by removing one hydrogen atom from an aromatic ring compound, and may be a monocyclic aryl group, or a fused ring aryl group, or a polycyclic aryl group, at least one of which is an aromatic ring system for polycyclic ring species. For example, "5-10 membered aryl" refers to aryl groups containing 5 to 10 ring atoms. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, perylene, triphenylene, and derivatives thereof.

"heteroaryl" means that on the basis of an aryl at least one carbon atom is replaced by a non-carbon atom which may be a N atom, an O atom, an S atom, etc. For example, "5-10 membered heteroaryl" refers to heteroaryl groups containing 5 to 10 ring atoms. Suitable examples include, but are not limited to: furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazole, indole, carbazole, pyrroloimidazole, pyrrolopyrrole, thienopyrrole, thienothiophene, furopyrrole, furofuran, thienofuran, benzisoxazole, benzisothiazole, benzimidazole, pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, phthalazine, quinoxaline, phenanthridine, primary pyridine, quinazoline, and quinazolinone.

Detailed explanation

One embodiment of the present invention provides a method for purifying an intermediate represented by formula (I), comprising the steps of:

s101: providing a crude product of an intermediate shown in a formula (I);

R₁、R₂and R₃Each independently is C_1-16Alkyl, 3-8 membered cycloalkyl, 5-10 membered aryl or 5-10 membered heteroaryl; in one embodiment, R₁And R₂Each independently is C_1-16Alkyl or 3-8 membered cycloalkyl; r₃Is C_1-16Alkyl, 3-8 membered cycloalkyl, 5-10 membered aryl or 5-10 membered heteroaryl.

In one embodiment, R₁、R₂And R₃Each independently is C_1-6Alkyl, 3-6 membered cycloalkyl, 6 membered aryl or 6 membered heteroaryl; further, R₁、R₂And R₃Each independently is C_1-4Alkyl or phenyl; further, R₁Is methyl, R₂Is ethyl, R₃Is methyl.

It is understood that the intermediates of formula (I) can be prepared by conventional methods and are understood to be within the scope of the present invention.

Further, in the step 101, in the crude product of the intermediate shown in the formula (I), the mass percentage content of impurities is 0.01-20%; furthermore, the mass percentage of the impurities is 0.01-10%; furthermore, the mass percentage of the impurities is 0.01-5%; furthermore, the mass percentage of the impurities is 0.01-3%.

Further, at least one impurity of the following structure is included:

further, it is preferable to prepare the intermediate represented by the formula (I) by the following method:

s1011: providing a compound with a structure shown in a formula (II);

the structural compound represented by the formula (II) may be obtained by commercially available raw materials or by conventional synthesis methods, and is not particularly limited herein. For example: the synthesis method comprises the following steps:

pulling out the keto carbonyl alpha active hydrogen of the intermediate shown in the formula (II-1), and then reacting with methylsulfonyl chloride to prepare the intermediate shown in the formula (II).

Further, the intermediate shown in the formula (II) can be prepared by a method comprising the steps of dissolving the intermediate shown in the formula (II-1) in a solvent (such as toluene, tetrahydrofuran and the like), slowly dropwise adding a hydrogen removing reagent (such as n-butyl lithium, lithium hydride and the like) under stirring at-100-10 ℃, continuously stirring for 1-8 h after dropwise adding, dropwise adding methylsulfonyl chloride at-30-0 ℃, and stirring for 10-30 h at 20-30 ℃. Adding saturated ammonium chloride solution to quench the reaction, separating an organic layer, extracting an aqueous layer with dichloromethane, combining the organic layers, washing with water, drying with anhydrous sodium sulfate, and removing the solvent to obtain the intermediate shown in the formula (II).

In one embodiment, R₁Is methyl, R₂Is ethyl, R₃The (R) -1- (3-alkoxy-4-alkoxy phenyl) -2- (alkyl sulfonyl) ethanol is (R) -1- (3-ethoxy-4-methoxy phenyl) -2- (methylsulfonyl) ethanol), and the raw material has wide sources and low price and can reduce the production cost.

S1012: carrying out asymmetric catalytic hydrogenation reaction on a compound with a structure shown in a formula (II) to prepare a crude product of an intermediate shown in the formula (I);

further, the catalyst adopted in the asymmetric catalytic hydrogenation reaction is a solid-phase chiral catalyst; further, the catalyst used in the asymmetric catalytic hydrogenation reaction has a structure represented by formula (a):

r is a high molecular polymer;

m is a transition metal;

x, Y are each independently halogen;

R₄is H or C_1-8An alkyl group.

Further, the high molecular polymer is selected from: cellulose, starch, hydroxy acrylates, polyethylene glycol, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polylactic acid or polybutylene succinate.

Further, the catalyst used in the asymmetric catalytic hydrogenation reaction has a structure represented by the following formula (B):

n is an integer of 12 to 65;

the catalyst introduces polyethylene glycol with a specific chain length on a molecule, so that on one hand, the catalyst is guided by the long chain with the specific chain length to assist the catalytic reaction of the catalyst, so as to improve the catalytic activity and further achieve the purpose of improving the asymmetric conversion rate; on the other hand, due to the existence of polyethylene glycol, the solid phase of the catalyst can be realized, and due to the existence of the molecular chain, the interaction between the heavy metal ions and the catalyst is improved, the metal ions are prevented from entering a reaction system, and the risk of heavy metal residue is reduced. The catalyst is simple in post-treatment, only needs simple suction filtration separation, is high in recovery rate, and is suitable for industrial production. In addition, the catalyst is adopted for catalytic reaction, so that the obtained reaction liquid has high purity and low heavy metal residual quantity, the difficulty of subsequent purification and separation can be effectively reduced, and a refined product with the impurity content of less than 0.1 percent can be simply and efficiently obtained by combining with a subsequent refining method.

In the structures shown in formula (A) and formula (B) "Represents a bisphosphine ligand, and the specific species of the bisphosphine ligand is not particularly limited, and may be BINAP or Diop; further, the bisphosphate ligand is BINAP.

Further, X and Y are the same; further, X and Y are both chlorine;

further, R₄Is H or C_1-4An alkyl group; further, R₄Is methyl to increase the asymmetric transformation ratio.

Further, n is an integer of 12 to 20; furthermore, n is 12, 13, 14, 15 or 16, and the technical personnel of the invention find that the polyethylene glycol with the specific chain length has higher catalytic activity for the reaction substrate and can more effectively reduce heavy metal residue.

Further, the catalyst employed in the asymmetric catalytic hydrogenation reaction in step S1012 has a structure represented by the following formula (C):

the catalyst has stronger selectivity to the substrate of the invention, and can effectively improve the asymmetric transformation rate.

Further, step S1012 includes the steps of:

mixing a structural compound shown in a formula (II), alkali, a catalyst and a solvent, reacting in a hydrogen atmosphere, and concentrating a reaction solution after the reaction is finished to obtain a crude product of an intermediate shown in the formula (I).

Further, the base is selected from: one or more of potassium tert-butoxide, potassium ethoxide and sodium ethoxide; more further, the base is selected from potassium tert-butoxide; further, the solvent is selected from: one or more of ethanol, methanol, isopropanol, toluene, dichloromethane, and cyclohexane; still further, the solvent is selected from toluene.

Further, in the above asymmetric catalytic hydrogenation reaction, the pressure is 5 to 45 atm. Further, the temperature in the above asymmetric catalytic hydrogenation reaction is 10 ℃ to 60 ℃, and further, the temperature in the above catalytic hydrogenation reaction is 25 ℃ to 45 ℃.

Further, in the above asymmetric catalytic hydrogenation reaction, the mass of the catalyst is 0.1% to 0.3% of the mass of the structural compound represented by the formula (II). Further, in the above asymmetric catalytic hydrogenation reaction, 1L to 2L of a solvent is added per 100g of the compound having the structure represented by the formula (II).

In addition, the reaction time of the asymmetric catalytic hydrogenation is not particularly limited, and the reaction can be monitored by a TCL plate, and after the reaction is finished, the reaction can be treated according to the conventional post-treatment.

S102: refining the crude product of the intermediate shown in the formula (I) by adopting a refining solvent to prepare a refined product of the intermediate shown in the formula (I); wherein the refined solvent is at least one of methyl isobutyl ketone, acetonitrile and butanone.

In one embodiment, the refining solvent is a combination of butanone and acetonitrile; further, the refined solvent is a mixed solvent composed of butyl ketone and acetonitrile in a volume ratio of 1: 1-10: 1; furthermore, the volume ratio of the butanone to the acetonitrile is 3: 1-5: 1.

In one embodiment, the refining solvent is a combination of methyl isobutyl ketone and acetonitrile; furthermore, the refining solvent is a mixed solvent composed of methyl isobutyl ketone and acetonitrile in a volume ratio of 1: 1-10: 1; furthermore, the volume ratio of the methyl isobutyl ketone to the acetonitrile is 3: 1-6: 1; further, the volume ratio of methyl isobutyl ketone to acetonitrile is 3:1, 3.2:1, 3.5:1, 3.7:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.5:1, 4.6:1, 4.8:1, or 5: 1.

Further, refining 1-20mL of refined solvent for each 1g of the crude product of the intermediate shown in the formula (I); further, 5 to 10mL of a purification solvent is used for purification per 1g of the crude product of the intermediate represented by the formula (I).

By adopting the refined solvent with the proportion, the purity of the product can be improved on the basis of effectively ensuring the yield.

Further, in step S102, the intermediate represented by formula (I) is recrystallized by cooling crystallization using the purified solvent; further, step S102 includes the steps of:

s1021: mixing the crude product of the intermediate shown in the formula (I) with a refined solvent, and dissolving at 50-80 ℃.

Further, dissolving at 50-60 deg.C.

S1022: cooling to 0-10 deg.C, standing, separating crystal, collecting crystal, and drying to obtain refined product of intermediate shown in formula (I).

Further, in step S1022, the mixed solution is cooled to 0 to 10 ℃ by a gradual cooling method;

further, the drying temperature is 45 ℃ to 60 ℃.

By adopting the refined solvent to purify the crude product of the intermediate shown in the formula (I), the purity of the intermediate shown in the formula (I) can be effectively improved, and the residual quantity of process impurities can be controlled below 0.1% on the basis of keeping a higher yield of the product. The refining method is simple, does not need special instruments and equipment, does not need special operation skills, and is particularly suitable for industrial production application.

The present invention will be described below with reference to specific examples.

The catalyst used for the asymmetric catalytic reaction in the following examples is

Wherein n is 12.

Example 1

(1) Synthesis of crude product

In an autoclave, under the argon atmosphere, 1000g of compound 1 is added from a charging port, 15L of toluene is added to fully dissolve the raw materials, the raw materials are fully stirred, argon is continuously introduced to carry out bubbling degassing, the bubbling is carried out for 1 hour continuously, and the degassing is finished. 2g of catalyst was added to the addition port and the addition port was quickly closed. Replacing argon with hydrogen, slowly introducing hydrogen to 3.0Mpa, and closing the inflation valve. The reaction is carried out at 25-40 ℃ with rapid stirring. When the pressure drops to a constant level, the reaction is deemed to have stopped. Sampling and liquid phase analysis are carried out to confirm the conversion rate. After the reaction, the system was filtered and concentrated to give a crude product with a purity (HPLC) of 93%.

(2) Refining

And (2) adding the crude product (200g) prepared in the step (1) into a refined solvent consisting of methyl isobutyl ketone (833ml) and acetonitrile (167ml), heating to 50-60 ℃ to dissolve the solid, cooling to 0-10 ℃ to crystallize for 1h, performing suction filtration, and drying at 50 ℃ under reduced pressure to obtain a refined white crystal product.

Example 2