Synthesis method of E3 ubiquitin ligase ligand

Abstract

The invention belongs to the technical field of medical intermediates, and particularly relates to a synthesis method of an E3 ubiquitin ligase ligand, which comprises the following steps: taking m-fluorobenzoic acid as a starting material, firstly preparing LDA, then introducing CO2 to react to obtain an intermediate, and then taking CDI as a condensing agent to perform ring closing reaction with 3-amino-2, 6-piperidinedione hydrochloride to obtain a product. All reaction steps of the synthesis method are not subjected to column chromatography separation, and post-treatment is more convenient; the raw material cost is saved, and kilogram-scale preparation of a target compound can be realized; the mixture is poured into ice water, filtered and dried after being completely separated out, and the problems of poor purity and excessive solvent residue are avoided; the optimized process route has the characteristics of cheap and easily available raw materials, mild reaction conditions, high yield and suitability for industrial production, and provides important theoretical significance and practical application value for large-scale production of enterprises.

Description

Technical Field

[0001] The invention belongs to the technical field of pharmaceutical intermediates, and particularly relates to a method for synthesizing an E3 ubiquitin ligase ligand. Background Art

[0002] E3 ubiquitin ligase ligands are important pharmacologically active parts in PROTAC molecular design. The common E3 ubiquitin ligase ligands reported in the literature mainly include CRBN, VHL, clAP and MDM2. Among them, CRBN ligand has good drug-like characteristics, the widest range of action, multiple binding sites, and can be connected to various types of linkers. PROTAC drugs designed based on CRBN ligands are the most studied drugs at this stage, with considerable market demand and application value.

[0003] The synthetic route of traditional E3 ubiquitin ligase ligands is as follows:

[0004]

[0005] It is based on 3-fluorophthalic acid and commercially available raw material 3-amino-2,6-piperidinedione hydrochloride as starting materials, and the target compound is obtained by one-step reaction, with a yield of 72.8%. However, due to the high price of raw material 3-fluorophthalic acid, the commercial price is 1094 yuan per 100g, and the cost is too high for mass production, and acetic acid is used as the reaction solvent, the amount of acetic acid used is large, and acetic acid residue is easy to cause poor product properties, and the amount of waste liquid generated by post-treatment caused by neutralization of acetic acid is large, which is unfriendly to the environment and unchanged for industrial production. Therefore, it is necessary to consider improving the synthesis route, using cheaper reaction raw materials, and using a suitable condensing agent to synthesize the compound.

[0006] In view of this, the inventors hope to provide a new method for synthesizing E3 ubiquitin ligase ligands, which has the advantages of high yield, less by-products, environmental protection, and easy scale-up production. Summary of the invention

[0007] The purpose of the present invention is to overcome the above problems existing in the traditional technology and provide a method for synthesizing an E3 ubiquitin ligase ligand.

[0008] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0009] A method for synthesizing an E3 ubiquitin ligase ligand, the structural formula of the E3 ubiquitin ligase ligand is as follows:

[0010]

[0011] The synthesis method of the E3 ubiquitin ligase ligand is shown in the following formula:

[0012]

[0013] Using m-fluorobenzoic acid as the starting material, LDA (lithium diisopropylamide) is first prepared, and then CO2 is introduced to react to obtain an intermediate. Then, CDI is used as a condensation agent to carry out a ring-closing reaction with 3-amino-2,6-piperidinedione hydrochloride to obtain the product.

[0014] Further, the preparation reaction formula of the intermediate is as follows:

[0015]

[0016] Furthermore, the preparation of the intermediate comprises the following steps:

[0017] Dissolve diisopropylamine in THF, cool to -50°C or below, add n-BuLi dropwise, and control the temperature to ≤-50°C; stir, add dropwise a THF solution containing m-fluorobenzoic acid, maintain the temperature at -50°C, pass CO2 gas, and rapidly heat the reaction system, control the temperature not to exceed -30°C. After the reaction system changes from turbid to clear, continue passing CO2 gas, heat naturally, and stir overnight;

[0018] A saturated ammonium chloride solution was added to quench the reaction, and the mixture was concentrated under reduced pressure to remove part of the solvent. The pH value was adjusted to 4 with a hydrochloric acid solution, MTBE was added, the layers were separated, the aqueous phase was extracted with MTBE, the aqueous phase was retained, and the pH value was adjusted to 1 with dilute hydrochloric acid. At this time, a large amount of solid was precipitated. After the solid was completely precipitated, it was filtered to obtain the intermediate.

[0019] Further, the reaction formula of the ring-closure reaction is as follows:

[0020]

[0021] Further, the specific steps of the ring-closure reaction are as follows:

[0022] The intermediate was dissolved in acetonitrile, CDI was added in batches, and the reaction temperature was controlled at room temperature to 35°C; after the reaction liquid was completely clarified, 3-amino-2,6-piperidinedione hydrochloride was added in batches, and the reaction temperature was controlled at room temperature to 35°C, and stirred at room temperature overnight;

[0023] The acetonitrile was removed by concentration under reduced pressure, and the remaining reaction solution was poured into water. A large amount of solid precipitated, which was filtered off with suction, and the filter cake was rinsed with water and dried to obtain the product.

[0024] The beneficial effects of the present invention are:

[0025] 1. The improved synthesis route has the following advantages: all reaction steps do not require column chromatography separation, making post-processing more convenient; it saves raw material costs and can achieve kilogram-scale preparation of the target compound; it only needs to be poured into ice water and wait for complete precipitation before filtering and drying, and there is no problem of poor purity and excessive solvent residue.

[0026] 2. The optimized process route has the characteristics of cheap and readily available raw materials, mild reaction conditions, high yield and suitability for industrial production, which provides important theoretical significance and practical application value for the company's scale-up production.

[0027] Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0029] Figure 1 It is the HNMR diagram of the product in the embodiment;

[0030] Figure 2 It is the HPLC figure of the product in the embodiment;

[0031] Figure 3 LCMS chart of the product in the example. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The specific designations of the abbreviations in this embodiment are as follows:

[0034] THF: Tetrahydrofuran

[0035] n-BuLi: n-butyllithium

[0036] MTBE: Methyl tert-butyl ether

[0037] CDI: carbonyldiimidazole;

[0038] The specific embodiments of the present invention are:

[0039] Example 1

[0040] Kilogram-scale preparation of intermediates:

[0041]

[0042] Dissolve diisopropylamine (2800.0g, 27.4mol) in 10LTHF, cool to below -50℃, add n-BuLi (2.5M inhexane) dropwise, and control the temperature to ≤-50℃. Stir for 0.5 hours, add THF solution containing m-fluorobenzoic acid (1200.0g, 8.6mol) dropwise, and keep the temperature at -50℃. After 3 hours, pass CO2 gas, and the reaction system will heat up rapidly. The temperature should be controlled not to exceed -30℃. After the reaction system changes from turbid to clear, continue to pass CO2 gas for 0.5 hours, heat naturally, and stir overnight.

[0043] Post-treatment: add 3L saturated ammonium chloride solution to quench the reaction, concentrate under reduced pressure to remove part of the solvent, adjust pH to 4 with 12L 2 M hydrochloric acid solution, add 4L MTBE, separate the liquid, extract the aqueous phase twice with 2L MTBE, retain the aqueous phase, and adjust pH to 1 with 2M dilute hydrochloric acid. At this time, a large amount of solid precipitates. After it is completely precipitated, filter and obtain the intermediate. The intermediate is 1165.3g of white solid, the crude yield is 73.6%, and it is directly used for the next step reaction.

[0044] Kilogram-scale preparation of products:

[0045]

[0046] The intermediate (1165.3 g, 6.3 mol) was dissolved in acetonitrile, and CDI (1950.0 g, 12.0 mol) was added in batches, and the reaction temperature was controlled at room temperature to 35°C. After the reaction liquid was completely clarified, 3-amino-2,6-piperidindione hydrochloride (900.0 g, 5.47 mol) was added in batches, and the reaction temperature was controlled at room temperature to 35°C. Stir at room temperature overnight, and 2% of the raw materials were unreacted when monitored by high-performance liquid chromatography.

[0047] Post-treatment: Concentrate under reduced pressure to remove most of the acetonitrile, pour the remaining reaction solution into 5L of water, a large amount of solid precipitates, filter, rinse the filter cake with 1L of water twice, and dry to obtain the product. The product (1426.7g, 81.9%) is a light yellow solid (HPLC purity>99%).

[0048] The results of the H NMR spectrum of the product are as follows Figure 1 As shown:

[0049] 1H NMR (400MHz, DMSO-d6) δ11.13(s,1H),8.01–7.90(m,1H),7.84–7.66(m,2H),5.16(dd,J=12.8,5.4H z,1H),2.90(ddd,J=17.1,13.9,5.5Hz,1H),2.67–2.51(m,2H),2.14–2.01(m,1H).MS(ESI)m / zcalcd for C 13 H9FN2O4[MH] + :275.22; found,275.23.

[0050] The improved synthesis route has the following main advantages: all reaction steps do not require column chromatography separation, making post-processing more convenient; it saves raw material costs and can achieve kilogram-scale preparation of the target compound; it only needs to be poured into ice water and wait for complete precipitation before filtering and drying, and there is no problem of poor purity or excessive solvent residue.

[0051] The optimized process route has the characteristics of cheap and readily available raw materials, mild reaction conditions, high yield and suitability for industrial production, which provides important theoretical significance and practical application value for the company's scale-up production. Subsequently, multiple batches of process synthesis of this compound were carried out, proving that the products synthesized by this route have good quality and good process stability, which increases the practicality of this route and provides an important basis for the preparation and development of new PROTAC series compounds and large-scale production.

[0052] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for synthesizing an E3 ubiquitin ligase ligand, characterized in that: The structural formula of the E3 ubiquitin ligase ligand is as follows: The synthesis method of the E3 ubiquitin ligase ligand is shown in the following formula: Using m-fluorobenzoic acid as the starting material, LDA is first prepared, and then CO2 is introduced to react to obtain an intermediate. Then, CDI is used as a condensation agent to carry out a ring-closing reaction with 3-amino-2,6-piperidinedione hydrochloride to obtain the product.

2. The synthesis method according to claim 1, characterized in that The preparation reaction formula of the intermediate is as follows:

3. The synthesis method according to claim 2, characterized in that The preparation of the intermediate comprises the following steps: Dissolve diisopropylamine in THF, cool to -50°C or below, add n-BuLi dropwise, and control the temperature to ≤-50°C; stir, add dropwise a THF solution containing m-fluorobenzoic acid, maintain the temperature at -50°C, pass CO2 gas, and rapidly heat the reaction system, control the temperature not to exceed -30°C. After the reaction system changes from turbid to clear, continue passing CO2 gas, heat naturally, and stir overnight; A saturated ammonium chloride solution was added to quench the reaction, and the mixture was concentrated under reduced pressure to remove part of the solvent. The pH value was adjusted to 4 with a hydrochloric acid solution, MTBE was added, the liquids were separated, the aqueous phase was extracted with MTBE, the aqueous phase was retained, and the pH value was adjusted to 1 with dilute hydrochloric acid. At this time, a large amount of solid was precipitated. After it was completely precipitated, it was filtered to obtain the intermediate.

4. The synthesis method according to claim 3, characterized in that The reaction equation of the ring-closure reaction is as follows:

5. The synthesis method according to claim 4, characterized in that The specific steps of the ring-closure reaction are as follows: The intermediate was dissolved in acetonitrile, CDI was added in batches, and the reaction temperature was controlled at room temperature to 35°C; after the reaction liquid was completely clarified, 3-amino-2,6-piperidinedione hydrochloride was added in batches, and the reaction temperature was controlled at room temperature to 35°C, and stirred at room temperature overnight; The acetonitrile was removed by concentration under reduced pressure, and the remaining reaction solution was poured into water. A large amount of solid precipitated, which was filtered off with suction, and the filter cake was rinsed with water and dried to obtain the product.

Images