Synthesis and use of free amino-polyethylene glycol-propionic acid of a single molecular weight
Free amino-polyethylene glycol-propionic acid can be directly prepared by synergistic catalysis of cerium chloride heptahydrate and sodium iodide under neutral conditions. This method solves the problems of cumbersome processes and difficulty in controlling product morphology in existing technologies, and realizes a highly efficient and simple preparation process that is suitable for pharmaceutical intermediates and bioconjugates.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN VOCATIONAL COLLEGE OF SOFTWARE & ENG (WUHAN OPEN UNIV)
- Filing Date
- 2026-05-14
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies are difficult to use efficiently to prepare pure free amino-polyethylene glycol-propionic acid, as the process is cumbersome and the product form is not easy to control.
Under neutral conditions, the synergistic effect of cerium chloride heptahydrate and sodium iodide was utilized to deprotect the single molecular weight BocNH-polyethylene glycol-tert-butyl propionate in a one-pot process, thereby simultaneously releasing the amino and carboxyl groups and obtaining the pure free target compound.
It simplifies the process flow, improves product purity and stability, is easy to operate, and has a yield of 75%-92%. It is suitable for the preparation of monodisperse polyethylene glycol derivatives with various chain lengths and is applicable to the synthesis of pharmaceutical intermediates and bioconjugation.
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Figure CN122444982A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of amino-polyethylene glycol-propionic acid preparation technology, and particularly to a method for synthesizing and applying free-state single-molecular-weight amino-polyethylene glycol-propionic acid. Background Technology
[0002] Polyethylene glycol (PEG) is widely used in pharmaceuticals, cosmetics, and materials due to its excellent biocompatibility, hydrophilicity, and low immunogenicity. However, in pharmaceutical applications, the purity, monodispersity, and impurity control requirements for PEG derivatives are extremely stringent. Terminal functionalization is key to determining the performance of PEG derivatives; different terminal groups impart different reactivity and applications. Because traditional PEG terminal hydroxyl groups have low reactivity and are difficult to stably bind to drug molecules, researchers often introduce more reactive functional groups such as amino and carboxyl groups to expand their applications in protein, peptide, small molecule, and gene therapy modifications.
[0003] Monodisperse polyethylene glycol (monodisperse PEG) has a precise molecular weight, well-defined structure, and controllable functionalization sites, which can significantly reduce the immunogenicity that may be caused by structural heterogeneity, providing greater controllability for drug design.
[0004] Existing literature and patent reports on methods for modifying monodisperse polyethylene glycol (PEG) hydroxyl groups into amino-PEG-propionic acid mainly involve first protecting the hydroxyl groups with p-toluenesulfonyl chloride (or methanesulfonyl chloride), then introducing the amino group using sodium azide or potassium phthalimide, or using amino-PEG chain extension to introduce the amino group, and finally obtaining the amino group through deprotection or reduction; using tert-butyl bromoacetate or tert-butyl acrylate to introduce the carboxyl group; the reaction equation is as follows:
[0005]
[0006]
[0007] The above methods for hydrolyzing tert-butyl ester generally use hydrogen chloride gas or a trifluoroacetic acid / dichloromethane system. However, the hydrolysis products obtained in this way are often hydrochloride or trifluoroacetate products, not free amino-polyethylene glycol-propionic acid. Amino-polyethylene glycol-propionic acid contains both amino and carboxyl groups, making it an amphoteric compound. To obtain the free compound, the isoelectric point of the compound must be measured, excess acid neutralized, and the pH value monitored using a pH meter. Even then, it cannot be guaranteed that the obtained product is entirely in the free state.
[0008] Therefore, existing technologies still have problems such as cumbersome processes and difficulty in controlling product form, and need further improvement. Summary of the Invention
[0009] In view of this, the present invention provides a method for synthesizing and applying a free, single-molecular-weight amino-polyethylene glycol-propionic acid. Under neutral conditions, the present invention utilizes the synergistic effect of cerium chloride heptahydrate and sodium iodide to directly deprotect single-molecular-weight BocNH-polyethylene glycol-tert-butyl propionate in a one-pot process, achieving simultaneous release of both amino and carboxyl groups, thus obtaining a pure, free target compound. This method is characterized by its simplicity, mild conditions, and controllable product morphology, showing broad application prospects in the synthesis of pharmaceutical intermediates and bioconjugation.
[0010] The first aspect of this invention is to provide a method for synthesizing free-state single-molecular-weight amino-polyethylene glycol-propionic acid, comprising the following steps: Under neutral conditions, BocNH-polyethylene glycol-tert-butyl propionate of a single molecular weight was mixed with cerium chloride heptahydrate and sodium iodide in an organic solvent and then subjected to a thermal reaction to obtain free amino-polyethylene glycol-propionic acid of a single molecular weight; the reaction formula is as follows:
[0011] Where n is a natural number greater than or equal to 1.
[0012] Preferably, the single molecular weight BocNH-polyethylene glycol-tert-butyl propionate comprises 2-20 ethylene glycol units.
[0013] Preferably, the molar ratio of the single molecular weight BocNH-polyethylene glycol-tert-butyl propionate to cerium chloride heptahydrate is 1:(1-2).
[0014] Preferably, the molar ratio of the single molecular weight BocNH-polyethylene glycol-tert-butyl propionate to sodium iodide is 1:(1-2).
[0015] Preferably, the mixing reaction process is as follows: at 10-30°C, add BocNH-polyethylene glycol-tert-butyl propionate of a single molecular weight to an organic solvent, then add cerium chloride heptahydrate and sodium iodide, raise the temperature to 40-80°C, keep the reaction at this temperature for 3-12 hours, and then stop the reaction.
[0016] Preferably, the process of ending the reaction includes: cooling, filtering, concentrating the solvent, adding dichloromethane to dissolve the concentrate, adding anhydrous sodium sulfate, filtering again, concentrating the filtrate, adding water to dissolve the concentrate, adding solvent to extract impurities, concentrating the resulting aqueous layer to obtain free single molecular weight amino-polyethylene glycol-propionic acid.
[0017] Preferably, the organic solvent used for extracting impurities is at least one of ethyl acetate, methyl tert-butyl ether, toluene, or dichloromethane; the concentration temperature is 30-55°C, the vacuum degree is -0.08 to -0.1 MPa, and the concentration time is 0.5-2 h.
[0018] Preferably, the mixed reaction is carried out in an organic solvent, said organic solvent being at least one of tetrahydrofuran, 1,4-dioxane, acetonitrile, methanol, ethanol, and N,N-dimethylformamide (DMF).
[0019] A second aspect of this invention is to provide the application of the free single molecular weight amino-polyethylene glycol-propionic acid synthesized by the above method in the PEG modification of protein or polypeptide drugs.
[0020] This invention employs cerium chloride heptahydrate (CeCl3·7H2O) and sodium iodide (NaI) in a neutral organic solvent to synergistically catalyze the removal of the Boc protecting group and tert-butyl ester group. CeCl3, as a Lewis acid, gently activates the carbonyl oxygen atom, promoting the cleavage of the Boc group; sodium iodide provides iodide ions, assisting tert-butyl ester in elimination or nucleophilic substitution reactions under mild heating conditions. The synergistic effect of these two agents efficiently completes dual deprotection in a neutral environment, avoiding the protonation of the amino group in a strong acid environment and the subsequent cumbersome neutralization process, thereby directly obtaining free amino-polyethylene glycol-propionic acid. The entire process does not require precise pH control, significantly simplifying the purification steps and improving the purity and stability of the product in its free state.
[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention provides a simple and efficient synthetic route for the direct preparation of free, single-molecular-weight amino-polyethylene glycol-propionic acid. This method avoids the complex pH adjustment steps following traditional acidic deprotection, and the resulting product exists in free form, which is beneficial for long-term storage and subsequent chemical conjugation applications. Furthermore, the process conditions are mild and the operation is simple, with yields reaching 75%-92%. It is suitable for the preparation of monodisperse polyethylene glycol derivatives of various chain lengths, providing high-purity, structurally well-defined raw materials for the PEG modification of downstream protein or peptide drugs, demonstrating broad application prospects in the fields of pharmaceutical intermediate synthesis and bioconjugation. Attached Figure Description
[0022] The present invention will be further described below with reference to the accompanying drawings.
[0023] Figure 1 The 1H NMR spectrum of the free single molecular weight amino-PEG8-propionic acid synthesized in Example 5 of this invention (… 1 H-NMR spectrum. Detailed Implementation
[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0025] Unless otherwise specified, all experiments were repeated three times, and the results are expressed as averages.
[0026] Example 1: A method for synthesizing free single molecular weight amino-polyethylene glycol-propionic acid, comprising the following steps: (1) In a 2 L three-necked flask, add 200 g (1.34 mol) of amino-polyethylene glycol and 1000 ml of methanol, stir, cool to 10 °C, and add 295.5 g (1.35 mol, 1.01 equivalent) of Boc2O dropwise, controlling the temperature at 10 ± 5 °C. After the addition is complete, react at this temperature for 5 h, take a sample for monitoring, and the reaction of the raw materials is complete.
[0027] The reaction formula is as follows:
[0028] Methanol was concentrated under reduced pressure, and 1000 ml of dichloromethane and 200 ml of saturated sodium bicarbonate aqueous solution were added. The mixture was extracted and separated. The aqueous layer was extracted twice with 400 ml of dichloromethane each time. The combined dichloromethane layers were washed once with 200 ml of saturated brine. The dichloromethane layer was then dried over anhydrous sodium sulfate, filtered, and concentrated at 40°C under a vacuum of -0.08 MPa to obtain 317 g of BocNH-PEG3-OH, with a yield of 95%.
[0029] (2) In a 2 L three-necked flask, add 100 g (0.40 mol) of BocNH-PEG3-OH from step (1), 200 ml of tetrahydrofuran, and 66.8 g (0.52 mol, 1.3 equivalent) of tert-butyl acrylate. Stir, add 5 ml of saturated potassium hydroxide, and react at 20±5℃ for 3 h. Take a sample to monitor the reaction, and the reaction of the raw materials is complete. Add 700 ml of ethyl acetate and 100 ml of water, extract and separate the layers. Extract the aqueous layer once with 200 ml of ethyl acetate, combine the ethyl acetate layers, and wash once with 100 ml of saturated brine. Then, dry the ethyl acetate layer with anhydrous sodium sulfate and filter. Concentrate at 40℃ and a vacuum of -0.08 MPa to obtain 139 g of BocNH-PEG3-tert-butyl propionate, with a yield of 92%.
[0030] The reaction formula is as follows:
[0031] (3) In a 1 L three-necked flask, add 50 g (0.13 mol) of BocNH-PEG3-propionate tert-butyl ester from step (2), 500 ml of acetonitrile, stir, add 23.8 g (0.16 mol, 1.2 equivalent) of sodium iodide, add 59.2 g (0.16 mol, 1.2 equivalent) of cerium chloride heptahydrate, heat to 70℃, react for 5 h, take a sample to monitor, and the reaction of the raw materials is complete. Cool down to 20-25℃, filter, concentrate the filtrate under reduced pressure to obtain a viscous liquid, add 500 ml of dichloromethane, stir to dissolve, add 30 g of anhydrous sodium sulfate, stir for 30 min, and filter. Concentrate at 40℃ and a vacuum of -0.08 MPa to obtain a pale yellow liquid, add 200 ml of water, add 50 ml of dichloromethane to extract impurities, concentrate the aqueous layer at 50℃ and a vacuum of -0.08 MPa to obtain 26.3 g of product, with a yield of 90%. 1 HNMR (400MHz, Chloroform-d) δ3.69-3.58(m,12H), 3.10(s,2H), 2.57-2.55(t,J=6.0Hz,2H).
[0032] The reaction formula is as follows:
[0033] Example 2 The difference from Example 1 is that the solvent in step (3) is replaced with 500 ml of ethanol, with a yield of 75%.
[0034] Example 3 The difference from Example 1 is that in step (2), 50 g of BocNH-PEG4-OH (0.17 mol), 100 ml of tetrahydrofuran, and 28.4 g of tert-butyl acrylate (0.22 mol, 1.3 equivalent) were used to obtain 67 g of product with a yield of 94%.
[0035] The reaction formula is as follows:
[0036] In step (3), 50 g (0.12 mol) of BocNH-PEG4-tert-butyl propionate, 21.3 g (0.14 mol, 1.2 equivalent) of sodium iodide, and 53.0 g (0.14 mol, 1.2 equivalent) of cerium chloride heptahydrate were used, with a yield of 91%.
[0037] 1 HNMR (400MHz, Chloroform-d) δ3.64-3.53(m,16H), 3.06(s,2H), 2.53-2.51(t,J=6.4Hz,2H).
[0038] The reaction formula is as follows:
[0039] Example 4 The difference from Example 1 is that in step (2), 50 g of BocNH-PEG5-OH (0.148 mol) and 28.49 g of tert-butyl acrylate (0.22 mol, 1.5 equivalent) were used to obtain 60.7 g of product with a yield of 88%.
[0040] The reaction formula is as follows:
[0041] In step (3), 50 g (0.107 mol) of BocNH-PEG5-tert-butyl propionate, 19.3 g (0.128 mol, 1.2 equivalent) of sodium iodide, and 48.0 g (0.128 mol, 1.2 equivalent) of cerium chloride heptahydrate were used, with a yield of 75%.
[0042] 1 HNMR (400MHz, Chloroform-d) δ3.85-3.71(m,20H), 3.24(s,2H), 2.71-2.69(t,J=6.4Hz,2H).
[0043] The reaction formula is as follows:
[0044] Example 5 The difference from Example 1 is that in step (3), 50 g (83.65 mmol) of BocNH-PEG8-propionate tert-butyl ester, 16.3 g (108.7 mmol, 1.3 equivalent) of sodium iodide, and 46.75 g (125.47 mmol, 1.5 equivalent) of cerium chloride heptahydrate were used, with a yield of 89%.
[0045] 1 HNMR (400MHz, Chloroform-d) δ3.81(t,J=4.9Hz,2H), 3.74-3.57(m,30H), 3.18(t,J=4.9Hz,2H), 2.56(t,J=6.0Hz,2H). See Figure 1 .
[0046] The reaction formula is as follows:
[0047] Comparative Example 1 The difference from Example 1 is that in step (3), the solvent is replaced with 500 ml of dichloromethane, the temperature is raised to reflux, there is a surplus of raw material, and the yield is 35%.
[0048] Comparative Example 2 The difference from Example 1 is that in step (3), sodium iodide was not added, but only 59.2 g of cerium chloride heptahydrate (0.16 mol, 1.2 equivalents) was added, and no product was detected.
[0049] Comparative Example 3 The difference from Example 1 is that in step (3), cerium chloride heptahydrate was not added, but only 23.8 g of sodium iodide (0.16 mol, 1.2 equivalent) was added, and no product was detected.
[0050] Comparative Example 4 The difference from Example 1 is that in step (3), cerium chloride heptahydrate was replaced with an equimolar amount of zinc chloride (ZnCl2) of other Lewis acids, 21.7 g (0.16 mol, 1.2 equivalents), and no product was detected.
[0051] Comparative Example 5 The difference from Example 1 is that in step (3), the reaction process is not heated, the reaction is carried out at 25°C for 12 hours, and the yield is 45%.
[0052] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for synthesizing free-state single-molecular-weight amino-polyethylene glycol-propionic acid, characterized in that, Includes the following steps: Under neutral conditions, BocNH-polyethylene glycol-tert-butyl propionate of a single molecular weight was mixed with cerium chloride heptahydrate and sodium iodide in an organic solvent and subjected to a heat-preserving reaction. After the reaction was completed, the mixture was purified and extracted to obtain free amino-polyethylene glycol-propionate of a single molecular weight.
2. The synthesis method according to claim 1, characterized in that, The single molecular weight BocNH-polyethylene glycol-tert-butyl propionate comprises 2-20 ethylene glycol units.
3. The synthesis method according to claim 1, characterized in that, The molar ratio of the single molecular weight BocNH-polyethylene glycol-tert-butyl propionate to cerium chloride heptahydrate is 1:(1-2).
4. The synthesis method according to claim 1, characterized in that, The molar ratio of the single molecular weight BocNH-polyethylene glycol-tert-butyl propionate to sodium iodide is 1:(1-2).
5. The synthesis method according to claim 1, characterized in that, The heat preservation reaction is carried out at a temperature of 40-80℃ for 3-12 hours.
6. The synthesis method according to claim 1, characterized in that, The organic solvent is at least one of tetrahydrofuran, 1,4-dioxane, acetonitrile, methanol, ethanol, and N,N-dimethylformamide.
7. The synthesis method according to claim 1, characterized in that, The purification method is as follows: cooling, filtering, concentrating to remove the solvent, adding dichloromethane to dissolve the concentrate, adding anhydrous sodium sulfate, filtering again, concentrating the filtrate, and adding water to dissolve the concentrate.
8. The synthesis method according to claim 1, characterized in that, The extraction method is as follows: solvent is added to extract impurities, the resulting aqueous layer is concentrated, and free single molecular weight amino-polyethylene glycol-propionic acid is obtained.
9. The synthesis method according to claim 8, characterized in that, The organic solvent used for extracting impurities is at least one of ethyl acetate, methyl tert-butyl ether, toluene, or dichloromethane. The concentration temperature is 30-55°C, the vacuum degree is -0.08 to -0.1 MPa, and the concentration time is 0.5-2 h.
10. The use of the free single molecular weight amino-polyethylene glycol-propionic acid synthesized by the method of any one of claims 1-9 in the PEG modification of protein or polypeptide drugs.