A method for preparing a lysine linear dimer

Abstract

The present invention belongs to the field of pharmaceutical synthesis technology, and specifically discloses a preparation method of a lysine linear dimer. The inventive method uses DL-lysine hydrochloride as raw material, and synthesizes target product (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam] hexanoic acid and its diastereomer by desalination and catalytic polymerization, and establishes a new chemical synthesis route different from traditional microbial method. The method can accurately control the degree of polymerization of DL-lysine, and produces a chemical main component based on linear dimer, is simple to operate, has a short synthetic route, high yield, high purity, and is suitable for large-scale production and application. The target product synthesized by the present invention is the process impurity of lysine aspirin intermediate DL-lysine hydrochloride, which is conducive to studying the impurity spectrum of lysine aspirin and is convenient for carrying out the quality control of lysine aspirin products.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical synthesis, and particularly relates to a method for preparing a lysine linear dimer, in particular to a method for preparing a lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers. Background Art

[0002] L-lysine hydrochloride will produce a dimer impurity during the high-temperature racemization process. This impurity is a linear aggregate formed by two lysine molecules contacting each other. Its chemical name is (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers. In the EP10.3 Pharmacopoeia Lysine Aspirin Variety Related Substances, this impurity is named Lysine Aspirin Impurity C.

[0003] During the quality research process for lysine aspirin, it is necessary to conduct research on lysine aspirin-related substances, including the development of analytical methods and methodological validation. To accurately quantify the content of lysine aspirin impurity C in lysine aspirin, it is necessary to synthesize lysine aspirin impurity C as a reference substance to establish a scientific analytical method for lysine aspirin-related substances.

[0004] In the prior art, lysine polymerization is typically achieved through biosynthesis, utilizing microbial secondary metabolism to produce L-lysine polymers with linked α-carboxyl and ε-amino groups. This typically results in a relatively high degree of polymerization, and the molecular weight cannot be precisely controlled, making it difficult to precisely synthesize dimers linked to the α-carboxyl and ε-amino groups. While there are literature reports on the synthesis of amino acid dimers, these generally produce cyclic dimers with a nonlinear molecular structure that does not meet the molecular structure requirements for this impurity. Therefore, it is necessary to develop a new synthesis process for the preparation of DL-lysine linear dimer impurities, which has practical significance for drug impurity research. Summary of the Invention

[0005] In order to solve one of the above-mentioned technical problems existing in the prior art, the present invention provides a method for preparing a lysine aspirin process impurity, a lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers. The method is simple to operate, has a short synthetic route, a high yield, and high purity.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a lysine linear dimer comprises the following steps:

[0008] Using DL-lysine hydrochloride as raw material, a solution containing DL-lysine is obtained after desalination;

[0009] The solution containing DL-lysine is subjected to polymerization reaction under catalytic conditions to obtain the target product, lysine linear dimer.

[0010] The synthetic route of the preparation method is as follows:

[0011]

[0012] in:

[0013] Compound I is DL-lysine hydrochloride;

[0014] Compound II is DL-lysine;

[0015] Compound III is a lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers, namely the target product lysine aspirin impurity C, which is a process impurity of the lysine aspirin intermediate DL-lysine hydrochloride.

[0016] As an embodiment of the present invention, the desalination is carried out by ion exchange, preferably in a cation exchange resin. The purpose of desalination is to remove chloride ions.

[0017] Further preferably, the model of the cation exchange resin is 731 type or 732 type cation exchange resin.

[0018] As an embodiment of the present invention, after desalting, the solution is first eluted with an eluent, and the eluate is then concentrated to obtain a solution containing DL-lysine.

[0019] As an embodiment of the present invention, the eluent is ammonia water, and the concentration of ammonia water is 3% to 10%.

[0020] As an embodiment of the present invention, when the eluent is concentrated, the concentration temperature is 60 to 90° C. and the vacuum degree is ≤-0.08 MPa.

[0021] As an embodiment of the present invention, the concentration of the DL-lysine-containing solution obtained after concentration is 15 wt% to 50 wt%, preferably 25 wt% to 35 wt%.

[0022] As an embodiment of the present invention, the catalytic conditions include using a mixed catalyst, wherein the mixed catalyst consists of a weakly basic catalyst and a metal catalyst.

[0023] Preferably, the weakly alkaline catalyst is selected from triethylamine and pyridine, more preferably triethylamine; the metal catalyst is selected from copper chloride, basic copper carbonate, zinc chloride, more preferably basic copper carbonate.

[0024] Further preferably, the mass ratio of the weakly alkaline catalyst to the metal catalyst is (8-12):1, more preferably 10:1.

[0025] As an embodiment of the present invention, the reaction temperature of the polymerization reaction is 120-200°C, preferably 150-160°C.

[0026] The polymerization reaction pressure is 0.5-1.5 MPa, preferably 0.8-1.2 MPa.

[0027] The polymerization reaction time is 4-10 hours, preferably 6 hours.

[0028] As an embodiment of the present invention, the solution containing DL-lysine is polymerized to obtain a solution containing the target product, which is then concentrated, crystallized, and dried in sequence to obtain a lysine linear dimer.

[0029] Preferably, the concentration is carried out by vacuum concentration to a concentration of the crystallization liquid of 55 wt% to 75 wt%, more preferably 55 wt% to 60 wt%.

[0030] As an embodiment of the present invention, the crystallization is carried out by cooling the temperature to -10 to 0°C, preferably to -10 to -5°C.

[0031] Preferably, the crystallization time is ≥8 h, more preferably the crystallization time is ≥10 h.

[0032] Further preferably, ethanol is added to the concentrated crystallization solution before crystallization, and then the temperature is lowered for crystallization; preferably, the amount of ethanol added is 35% to 40% of the mass of the concentrated crystallization solution.

[0033] As an embodiment of the present invention, after the cooling crystallization, the crystals are first filtered out and then dried.

[0034] Preferably, the drying is carried out by drying at a temperature of 45 to 50° C. and a drying time of 6 to 8 hours.

[0035] The present invention provides a method for preparing a lysine linear dimer. DL-lysine hydrochloride is used as a raw material, and desalination is performed on a cation exchange resin to remove chloride ions. The method is then eluted with ammonia water, and the eluate is concentrated to obtain an aqueous solution containing DL-lysine. The DL-lysine is then polymerized under high temperature and high pressure using a mixed catalyst to obtain the target product, a lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers. This target product is a process impurity of the lysine aspirin intermediate DL-lysine hydrochloride, and is beneficial for studying the impurity profile of lysine aspirin and for quality control of lysine aspirin products.

[0036] The present invention has the following beneficial effects: Using DL-lysine hydrochloride as the starting material, a novel chemical synthesis route, distinct from traditional microbial methods, has been established to produce a lysine linear dimer. This method is simple to operate, has a short synthesis route, and offers high yield and purity, making it suitable for large-scale production and application.

[0037] The method of the present invention can accurately control the polymerization degree of DL-lysine by controlling the polymerization reaction pressure, polymerization reaction temperature and polymerization reaction time, and produce a chemical main component mainly composed of linear dimers.

[0038] The lysine linear dimer prepared by the method of the present invention is detected by the EP10.3 lysine aspirin related substance method, and the main peak liquid phase retention time is 17.2-17.5 minutes, which is consistent with the lysine aspirin impurity C reference substance positioning solution. The mass spectrum and nuclear magnetic resonance hydrogen spectrum confirm that the main component is the lysine aspirin impurity C molecular structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the localization map of the reference substance of lysine aspirin impurity B;

[0040] Figure 2 This is the location map of the reference substance of lysine aspirin impurity C;

[0041] Figure 3 is the mass spectrum of compound III synthesized in Example 1 of the present invention;

[0042] Figure 4 It is the H NMR spectrum of compound III synthesized in Example 1 of the present invention. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the following examples. The specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention in any way. In addition, descriptions of known technologies are omitted in the following description to avoid unnecessary confusion. Such technologies are also described in many publications.

[0044] definition

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly used in the art to which this invention belongs.

[0046] As used herein, the term "about" refers to a range of ±20% of the value that follows. In some embodiments, the term "about" refers to a range of ±10% of the value that follows. In some embodiments, the term "about" refers to a range of ±5% of the value that follows.

[0047] The following examples and accompanying drawings are provided to facilitate understanding of the present invention. However, it should be understood that these examples and accompanying drawings are intended to illustrate the present invention only and are not intended to limit the present invention in any way. The actual scope of protection of the present invention is set forth in the claims. It should be understood that any modifications and / or variations may be made without departing from the spirit of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for preparing a lysine linear dimer, comprising the following steps:

[0050] 182.6 g (0.1 mol) of Compound I (DL-lysine hydrochloride) was dissolved in 1278 g of deionized water to prepare a 12.5 wt% DL-lysine hydrochloride aqueous solution, which was then passed through a 731 cation exchange resin column for desalination. After loading, the resin column was rinsed with deionized water until the effluent was free of chloride ions (monitored by a nitrate reagent), then eluted with 3 wt% ammonia water. Collection of the eluate began when DL-lysine was present and ceased when it was no longer present (monitored by the ninhydrin method for the presence of DL-lysine).

[0051] The eluate was transferred to a concentration bottle and concentrated under vacuum at a temperature of 60 ± 2 °C and a vacuum degree of ≤ -0.08 MPa until the density of the concentrate reached 1.05 g / cm 3 The concentration was stopped at 400 nm to obtain 381 g of a concentrated solution of compound II (DL-lysine) with a concentration of 31.5 wt % and a yield of 82.1%.

[0052] 200 g of a 31.5 wt% solution of compound II was added to a 500 mL autoclave, and 2 g of triethylamine and 0.2 g of basic copper carbonate were added as catalysts. The autoclave was sealed, the reaction temperature was controlled at 120-130° C., the reaction pressure was controlled at 0.5-0.7 MPa, the polymerization reaction was carried out for 10 h, and the reaction was stopped to obtain a reaction solution containing the target product, compound III.

[0053] The reaction solution was concentrated in vacuo to contain about 57 wt% of compound III. 40 g of ethanol was added, and the temperature was lowered to -10°C. The mixture was slowly stirred for crystallization for 10 h, filtered, and the damp crystals were dried at 45-50°C for 8 h to obtain 38.5 g of compound III with a yield of 65.1%.

[0054] The mass spectrum of the synthesized compound III is shown in Figure 3 , NMR hydrogen spectrum see Figure 4 HPLC analysis showed that the total content of the obtained lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomer mixture was 98.2%.

[0055] Example 2

[0056] This embodiment provides a method for preparing a lysine linear dimer, comprising the following steps:

[0057] 182.6 g (0.1 mol) of Compound I (DL-lysine hydrochloride) was dissolved in 1278 g of deionized water to prepare a 12.5 wt% DL-lysine hydrochloride aqueous solution, which was then passed through a 731 cation exchange resin column for desalination. After loading, the column was rinsed with deionized water until the effluent was free of chloride ions (monitored by a nitrate reagent), and then eluted with 10 wt% ammonia water. Collection of the eluate began when DL-lysine was present and ceased when it ceased.

[0058] The eluate was transferred to a concentration bottle and concentrated under vacuum at a temperature of 60 ± 2 °C and a vacuum degree of ≤ -0.08 MPa until the density of the concentrate reached 1.06 g / cm 3 The concentration was stopped at 400 nm to obtain 395 g of a concentrated solution of compound II (DL-lysine) with a concentration of 32.0 wt % and a yield of 86.5%.

[0059] 200 g of a 32.0 wt% solution of compound II was added to a 500 mL autoclave, and 2 g of triethylamine and 0.2 g of basic copper carbonate were added as catalysts. The autoclave was sealed, the reaction temperature was controlled at 180-200 ° C, the reaction pressure was controlled at 1.1-1.2 MPa, the polymerization reaction was carried out for 4 h, and the reaction was stopped to obtain a reaction solution containing the target product compound III.

[0060] The reaction solution was concentrated in vacuo to contain about 56 wt % of compound III. 40 g of ethanol was added, and the temperature was lowered to -5°C. The mixture was slowly stirred for crystallization for 12 h, filtered, and the damp crystals were dried at 45-50°C for 6 h to obtain 39.5 g of compound III with a yield of 66.8%.

[0061] HPLC analysis showed that the total content of the obtained lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomer mixture was 98.0%.

[0062] Example 3

[0063] This embodiment provides a method for preparing a lysine linear dimer, comprising the following steps:

[0064] 182.6 g (0.1 mol) of Compound I (DL-lysine hydrochloride) was dissolved in 1278 g of deionized water to prepare a 12.5 wt% DL-lysine hydrochloride aqueous solution, which was then passed through a 731 cation exchange resin column for desalination. After loading, the column was rinsed with deionized water until the effluent was free of chloride ions (monitored by a nitrate reagent), and then eluted with 5 wt% ammonia water. Collection of the eluate began when DL-lysine was present and ceased when it ceased.

[0065] The eluate was transferred to a concentration bottle and concentrated under vacuum at a temperature of 90 ± 2 °C and a vacuum degree of ≤ -0.08 MPa until the density of the concentrate reached 1.05 g / cm 3 The concentration was stopped at 40°C to obtain 390 g of a concentrated solution of compound II (DL-lysine) with a concentration of 31.5 wt % and a yield of 84.0%.

[0066] 200 g of a 31.5 wt% solution of compound II was added to a 500 mL autoclave, and 2 g of triethylamine and 0.2 g of basic copper carbonate were added as catalysts. The autoclave was sealed, the reaction temperature was controlled at 150-160° C., the reaction pressure was controlled at 0.8-1.0 MPa, the polymerization reaction was carried out for 6 h, and the reaction was stopped to obtain a reaction solution containing the target product, compound III.

[0067] The reaction solution was concentrated in vacuo to contain about 60% of compound III. 40 g of ethanol was added, and the temperature was lowered to -5°C. The mixture was slowly stirred for crystallization for 12 h, filtered, and the damp crystals were dried at 45-50°C for 6 h to obtain 38.8 g of compound III with a yield of 65.6%.

[0068] HPLC analysis showed that the total content of the obtained lysine linear dimer (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomer mixture was 98.4%.

[0069] Experimental example: Target product confirmation

[0070] Lysine dimers include lysine aspirin impurity B and lysine aspirin impurity C, which differ in their molecular structures. Lysine aspirin impurity B is an acylation product at the 2-amino group of lysine, and its molecular structure is sterically hindered, making it difficult to form. Lysine aspirin impurity C, on the other hand, is a dimer formed by acylation between the 6-amino group and the 1-carboxyl group. This is a head-to-head reaction, with a linear structure and minimal steric hindrance, making it easier to form.

[0071] The EP10.3 lysine aspirin related substance method was used, and the purchased standard was used as the standard reference. After the liquid phase method reference was used to locate the reference, the retention time of the lysine aspirin impurity B reference was about 20.5 minutes, and the retention time of the lysine aspirin impurity C reference was about 17.3 minutes. Figure 1 and Figure 2 .

[0072] Liquid chromatography detection showed that the liquid chromatography peak time of the target product obtained in Example 1 of the present invention was consistent with that of the standard product of lysine impurity C.

[0073] Detected by ESI(+)-MS mass spectrometry, see Figure 3 , the [M+H] of the target product obtained in Example 1 + The molecular weight is 275.5, which is consistent with the molecular weight of compound III.

[0074] The results of H NMR analysis are shown in Figure 4 The structure of the target product obtained in Example 1 is consistent with that of compound III.

[0075] The above characterization information proves that the product obtained in Example 1 is (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers.

[0076] The target products obtained in Example 2 and Example 3 were also tested, and the results were the same as those of the product in Example 1.

[0077] The method of the present invention uses DL-lysine hydrochloride as a raw material, and synthesizes the target product (2RS)-2-amino-6-[(2R)-2,6-diaminocaprolactam]hexanoic acid and its diastereomers through desalination and catalytic polymerization reaction, and uses the target product as the process impurities of DL-lysine hydrochloride, an intermediate of lysine aspirin. The method is conducive to studying the impurity spectrum of lysine aspirin and facilitates the quality control of lysine aspirin products.

[0078] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present invention. Therefore, the technical solutions of the present invention are not limited to the above-described specific embodiments; all technical variations based on the technical solutions of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing a lysine linear dimer, characterized in that: The following steps are involved: Using DL-lysine hydrochloride as raw material, a solution containing DL-lysine is obtained after desalination; The solution containing DL-lysine is subjected to polymerization reaction under catalytic conditions to obtain the target product, lysine linear dimer; The catalytic conditions include using a mixed catalyst, the mixed catalyst consisting of a weak alkaline catalyst and a metal catalyst, the weak alkaline catalyst is selected from triethylamine, and the metal catalyst is selected from basic copper carbonate; the mass ratio of the weak alkaline catalyst to the metal catalyst is (8-12):1; The reaction temperature of the polymerization reaction is 150-160° C.; the polymerization reaction pressure is 0.8-1.2 MPa; and the polymerization reaction time is 4-10 hours.

2. The preparation method according to claim 1, characterized in that The desalination is performed by ion exchange.

3. The preparation method according to claim 1, characterized in that Desalination is carried out using cation exchange resin.

4. The preparation method according to claim 3, characterized in that The model of the cation exchange resin is 731 type or 732 type cation exchange resin.

5. The preparation method according to any one of claims 1 to 4, characterized in that After desalting, the solution is eluted with an eluent, and the eluate is concentrated to obtain a solution containing DL-lysine.

6. The preparation method according to claim 5, characterized in that The eluent is ammonia water, and the concentration of ammonia water is 3% to 10%; And / or, the concentration temperature is 60-90° C. and the vacuum degree is ≤-0.08 MPa; And / or, the concentration of the DL-lysine-containing solution obtained after the concentration is 15 wt% to 50 wt%.

7. The preparation method according to claim 6, characterized in that The concentration of the DL-lysine solution obtained after the concentration is 25 wt% to 35 wt%.

8. The preparation method according to claim 1, characterized in that The mass ratio of the weakly alkaline catalyst to the metal catalyst is 10:

1.

9. The preparation method according to claim 1, characterized in that The solution containing DL-lysine is polymerized to obtain a solution containing the target product, which is then concentrated, crystallized and dried in sequence to obtain a lysine linear dimer.

10. The preparation method according to claim 9, characterized in that The concentration is carried out by vacuum concentration to a concentration of the crystallized liquid of 55 wt% to 75 wt%.

11. The preparation method according to claim 10, characterized in that: The crystallization solution is concentrated to a concentration of 55 wt% to 60 wt%.

12. The preparation method according to claim 9, characterized in that The crystallization is carried out by cooling crystallization to -10 to 0°C; and / or, Crystallization time ≥8h.

13. The preparation method according to claim 12, characterized in that Cooling to -10 to -5°C for crystallization; and / or, Crystallization time ≥10h.

14. The preparation method according to claim 12, characterized in that Before crystallization, ethanol is added to the concentrated crystallization solution, and then the temperature is lowered for crystallization.

15. The preparation method according to claim 14, characterized in that The amount of ethanol added is 35% to 40% of the mass of the crystallized liquid after the concentration treatment.

16. The preparation method according to claim 9, characterized in that After the cooling crystallization, the crystals are first filtered out and then dried.

17. The preparation method according to claim 16, characterized in that The drying is carried out in a drying method, the drying temperature is 45-50° C., and the drying time is 6-8 hours.

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