Synthesis method of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether

Abstract

The invention provides a synthetic method of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether. The synthetic method comprises the following steps: S1, synthesizing [1-14C] acetic acid; s2, synthesizing [1-14C]-2-bromoacetic acid; s3, synthesizing [1-14C]-2-bromoethanol; s4, synthesizing hydroxyl trityl protection-[1-14C]-2-bromoethanol; s5, synthesizing hydroxyl-protected [1-14C] methoxypolyethylene glycol; s6, synthesis of [1-14C] methoxypolyethylene glycole.The overall synthesis method is universal, stable and economical, a methoxypolyethylene glycolether compound with the specified polymerization degree can be synthesized, and the C-14-labeled methoxypolyethylene glycolether serves as an important intermediate for synthesizing PEG of different polymers and is used for modification of C14-labeled PEG of various small molecule drugs, so that the application prospect is wide. Therefore, the PEG-modified drug can be used as a tracer for performance research of the PEG-modified drug in pharmacokinetics and other aspects.

Description

Technical Field

[0001] The invention belongs to the field of radiochemical synthesis, and particularly relates to a synthesis method of polyethylene glycol monomethyl ether labeled with radioisotope carbon-14. Background Art

[0002] Polyethylene glycol (PEG) is a high molecular polymer obtained by the gradual addition polymerization of ethylene oxide and water or ethylene glycol. When polyethylene glycol is combined with biomaterials, its "stealth" effect mainly comes from its hydrophilicity and steric hindrance. The polyethylene glycol molecular chain contains a large number of ether bonds, which can form hydrogen bonds with water molecules, making polyethylene glycol have good hydrophilicity. In the body, the polyethylene glycol chain can form a hydration layer on the surface of the material. This hydration layer is like a "protective cover" that can prevent the non-specific adsorption of biological macromolecules such as proteins on the surface of the material. For example, in the drug delivery system, if the surface of the nano drug carrier is modified with polyethylene glycol, the adsorption of plasma proteins can be reduced, thereby avoiding recognition and clearance by the mononuclear phagocyte system and prolonging the circulation time of the drug in the body. This characteristic of reducing the non-specific interaction between biomaterials and components in the body is vividly called the "stealth" effect. It is precisely because of this characteristic that polyethylene glycol is widely regarded as a "gold standard" for biomaterials in the biomedical field.

[0003] With the continuous deepening of research, the development technology of PEG-modified drugs has been continuously improved, and many PEG-modified drugs have been approved for marketing by the FDA and other drug regulatory authorities. The emergence of more and more PEG-modified drugs means that these PEG-modified drugs have various pharmacokinetic and other performance studies, which means that the demand for carbon-14 labeled PEG will increase. So far, there are not many literatures on the synthesis method of carbon-14 labeled PEG. In 2007, Gary Shemilt et al. reported a method for synthesizing carbon-14 labeled PEG. This method generates sodium salt of PEG and then reacts it with doubly labeled ethylene oxide to obtain carbon-14 labeled polyethylene glycol polymer. This reaction route and possible impurities such as Figure 1 As shown, this method has many defects. From the experimental data, it can be seen that there are small molecule labeled fragment impurities in the synthesized polymer. After analysis, it is due to the formation of oligomers by the double-labeled ethylene oxide. In addition, the dispersion of the overall labeled product is significantly increased, and it is impossible to accurately control the polymer to react with only one labeled monomer, which makes it difficult to meet the strict requirements of different PEG-modified drugs on the dispersion of PEG fragments and the molecular weight specificity of polymerization degree.

[0004] Considering that the dispersion and molecular weight of the PEG fragment of each PEG-modified drug are specific, it is of utmost importance to synthesize the carbon-14 labeled PEG fragment while maintaining the original PEG dispersion and molecular weight of each PEG-modified drug as much as possible. Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14, to synthesize polyethylene glycol monomethyl ether labeled with carbon-14, and to use the carbon-14 labeled polyethylene glycol monomethyl ether as an important intermediate for synthesizing PEG of different polymers, and for carbon-14-labeled PEG modification of various small molecule drugs, thereby being used as a tracer for the performance study of the PEG modified drugs in pharmacokinetics and other aspects.

[0006] To achieve the above purpose, the present technical solution provides a method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14, comprising the following steps: S1: Synthesis [1- 14 C] Acetic acid: Under negative pressure, 14 C-barium carbonate is added with concentrated acid to generate 14 C-carbon dioxide, 14 C-carbon dioxide is introduced into the methylmagnesium bromide solution to react and pass an inert gas. After the reaction is completed, dilute acid is added to quench, and then the organic phases are combined after multiple extractions with an organic solvent, dried, filtered, and the solvent is distilled off at normal pressure to obtain [1- 14 C] acetic acid; S2: Synthesis [1- 14 C]-2-Bromoacetic acid: Stored in sealed reactor [1- 14 C] acetic acid and trifluoroacetic anhydride are added, followed by the addition of a bromination reagent for reaction, after which water is added to quench and concentrate, followed by dilution with an organic solvent, drying, filtering, and concentrating to obtain [1- 14 C]-2-bromoacetic acid; S3: Synthesis [1- 14 C]-2-bromoethanol: Under inert gas protection, [1- 14 C]-2-bromoacetic acid is dissolved in the first organic solvent and a reducing agent is added to react. After the reaction is completed, water is added to quench the reaction, followed by dilution with a second organic solvent, drying, filtering, and concentration to obtain [1- 14 C]-2-bromoethanol; S4: Synthesis of hydroxytrityl-protected-[1- 14 C]-2-Bromoethanol Under inert gas protection, [1- 14C]-2-bromoethanol is dissolved in a third organic solvent, an organic base and a hydroxyl protecting agent are added to react, water is added to quench after the reaction is completed, and then extracted with a fourth organic solvent, washed with water, dried, filtered, concentrated, and separated by rapid column chromatography to obtain hydroxytrityl-protected-[1- 14 C]-2-bromoethanol; S5: Synthesis of Hydroxyl Protected [1- 14 C] Polyethylene glycol monomethyl ether: Under the protection of inert gas, polyethylene glycol monomethyl ether mPEG is dissolved in the fifth organic solvent and hydroxytrityl-protected-[1- 14 C]-2-bromoethanol reaction, after the reaction is completed, water is added to quench, after the quenching is completed, extraction is performed with a sixth organic solvent, washing with saturated brine, drying, filtering, concentrating, and rapid column chromatography separation and purification are performed to obtain hydroxyl-protected [1- 14 C] Polyethylene glycol monomethyl ether; S6: Synthesis [1- 14 C] Polyethylene glycol monomethyl ether: The hydroxyl group is protected [1- 14 C] polyethylene glycol monomethyl ether is dissolved in the seventh organic solvent and a deprotecting agent is added to react. After the reaction is completed, the seventh organic solvent is concentrated and purified by rapid column chromatography to obtain [1- 14 C] Polyethylene glycol monomethyl ether.

[0007] The synthesis method of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether proposed in this scheme is 14 C-barium carbonate is a radioactive isotope raw material, which is converted into 14 C-carbon dioxide, reacts with methylmagnesium bromide Grignard reagent to obtain [1- 14 C]-acetic acid, and then react with trifluoroacetic anhydride and liquid bromine to generate [1- 14 C]-2-bromoacetic acid, and then the carboxyl group is reduced to generate 1-[ 14 C]-2-bromoethanol, reacts with a hydroxyl protecting agent to generate hydroxyl protected [1- 14 C]-2-bromoethanol, and then reacted with mPEG of different polymerization degrees to generate hydroxyl-protected [1- 14 C]-polyethylene glycol monomethyl ether, and then react with a hydroxyl deprotection reagent to obtain [1- 14 C]-polyethylene glycol monomethyl ether, the specific activity of the final product is: 1.0~10mCi / g; the chemical purity and radiochemical purity are both greater than 98%.

[0008] Specific: Regarding step S1: 14 C-barium carbonate, as a radioisotope raw material, is the key starting material for introducing carbon-14 labeling. It will be converted into 14C-carbon dioxide, and then participate in the reaction, methylmagnesium bromide solution is a Grignard reagent, providing carbon anion for 14 C-carbon dioxide undergoes a nucleophilic addition reaction to give [1- 14 C]-acetic acid.

[0009] The reaction of step S1 of this scheme is carried out under negative pressure, which helps to promote 14 C-Carbon dioxide from 14 C-barium carbonate is released and smoothly enters the methylmagnesium bromide solution to participate in the reaction. Inert gas needs to be introduced to remove oxygen and moisture from the reaction system. Inert gas protection can ensure that the reaction proceeds smoothly in an anhydrous and oxygen-free environment.

[0010] In step S1, the concentrated acid is selected from phosphoric acid, sulfuric acid, hydrochloric acid or any combination thereof.

[0011] In step S1, the organic solvent is selected from dichloromethane, diethyl ether or any combination thereof.

[0012] In step S1, 14 C-barium carbonate is added with concentrated acid to generate 14 C-carbon dioxide, 14 C-carbon dioxide is introduced into the methylmagnesium bromide solution for reaction and inert gas is introduced for reaction for 1-3 hours, and the reaction temperature is set at 0-25°C. After the reaction is completed, dilute acid is added to quench, and then the organic phases are combined after multiple extractions with organic solvents, dried, filtered, and the solvent is distilled off at normal pressure to obtain [1- 14 C] acetic acid.

[0013] In one specific embodiment, the reaction equation of step S1 is as follows: .

[0014] Regarding the [1- 14 The chemical formula of acetic acid is shown in formula (II) below, where the asterisk indicates the position of carbon-14: .

[0015] Regarding step S2: 14 C] Acetic acid is used as the starting material, trifluoroacetic anhydride is used as the acylating agent, and liquid bromine is used as the brominating agent. Trifluoroacetic anhydride has a strong acylating ability and can convert the carboxyl group of acetic acid into a more active acyl group, which is beneficial for the subsequent introduction of bromine atoms. The brominating agent is a source of bromine atoms and is used to bromine the intermediate after acylation.

[0016] Step S2 of this scheme is carried out in a sealed reactor to prevent trifluoroacetic anhydride and bromination reagent from volatilizing into the air, causing raw material loss, environmental pollution and harm to operators.

[0017] In step S2, the bromination reagent is selected as liquid bromine.

[0018] In step S2, the organic solvent is selected as one or any combination of dichloromethane or diethyl ether.

[0019] In step S2, [1- 14 C] acetic acid and trifluoroacetic anhydride, then add bromination reagent to react for 12-20 hours, the reaction temperature is set at 0-25°C, after the reaction is completed, add water to quench and concentrate, then dilute with an organic solvent, dry, filter, and concentrate to obtain [1- 14 C]-2-bromoacetic acid.

[0020] In one specific embodiment, the reaction equation of step S2 is as follows: .

[0021] Regarding the synthesis of step S2 [1- 14 The chemical formula of -2-bromoacetic acid is shown in the following formula (III): .

[0022] In step S3, [1- 14 C]-2-bromoacetic acid is used as a reaction material to react with a reducing agent, and the reducing agent converts [1- 14 C] The carboxyl group in 2-bromoacetic acid is reduced to a hydroxyl group, while having little effect on the bromine atom in the molecule. The reaction is carried out under the protection of an inert gas to prevent oxygen and moisture from entering the reaction system.

[0023] In step S3, the first organic solvent is selected as one or any combination of tetrahydrofuran or diethyl ether. The anhydrous solvent can avoid the interference of water on the reaction. Ether solvents such as tetrahydrofuran have good solubility for reactants and products, and can make the reaction proceed smoothly.

[0024] In step S3, the reducing agent is selected as one or any combination of borane tetrahydrofuran or borane dimethyl sulfide. Borane reducing agents have strong reducing properties and can selectively reduce carboxyl groups to hydroxyl groups while having little effect on bromine atoms in the molecule.

[0025] In step S3, the second organic solvent is selected as one or any combination of dichloromethane or diethyl ether.

[0026] In step S3, [1- 14C]-2-bromoacetic acid is dissolved in the first organic solvent and a reducing agent is added to react for 2-5 hours at a reaction temperature of 0-25°C. After the reaction is completed, water is added to quench the reaction, followed by dilution with a second organic solvent, drying, filtering, and concentration to obtain [1- 14 C]-2-bromoethanol.

[0027] In one specific embodiment, the reaction equation of step S3 is as follows: .

[0028] Regarding [1- 14 The chemical formula of [C]-2-bromoethanol is shown in the following formula (IV): .

[0029] In step S4, [1- 14 C]-2-bromoethanol is protected by hydroxyl group to generate hydroxytrityl protected-[1- 14 C]-2-bromoethanol, hydroxyl protecting agent is the same as [1- 14 C] The hydroxyl group of -2-bromoethanol reacts to form a stable ether bond, protecting the hydroxyl group from interference in subsequent reactions, and the organic base neutralizes the hydrogen chloride produced during the reaction to promote the reaction to the right.

[0030] In step S4, the third organic solvent is selected from tetrahydrofuran, dichloromethane or diethyl ether or any combination thereof, and the fourth organic solvent is selected from dichloromethane or ethyl acetate or any combination thereof.

[0031] In step S4, the organic base is selected from triethylamine, diisopropylethylamine or imidazole or any combination thereof.

[0032] In step S4, the hydroxyl protecting agent is selected as triphenylmethyl chloride, and the organic base reacts with triphenylmethyl chloride to generate triphenylmethyl cation and chloride ion. The triphenylmethyl cation has a high electrophilicity, [1- 14 C]-2-bromoethanol hydroxyl oxygen atom, forming a positively charged intermediate, then the intermediate loses a proton to generate hydroxytrityl-protected-[1- 14 C]-2-bromoethanol.

[0033] In one specific embodiment, the reaction equation of step S4 is as follows: .

[0034] Regarding the hydroxytrityl protection of step S4 -[1- 14 The chemical formula of -2-bromoethanol is shown in the following formula (V): .

[0035] Step S5 is to protect the hydroxytrityl group-[1- 14 C]-2-bromoethanol reacts with polyethylene glycol monomethyl ethers of different polymerization degrees to generate hydroxyl-protected [1- 14 C] Polyethylene glycol monomethyl ether, hydroxytrityl protected-[1- 14 C]-2-bromoethanol is used as an electrophilic reagent in the nucleophilic substitution reaction, providing a carbon-14 label and a portion to be connected to polyethylene glycol monomethyl ether. Polyethylene glycol monomethyl ethers of different polymerization degrees are used as nucleophilic reagents, and the oxygen atom at the hydroxyl end thereof has nucleophilicity and can attack the electrophilic reagent to cause a nucleophilic substitution reaction.

[0036] In step S5, polyethylene glycol monomethyl ether mPEG with different polymerization degrees is selected to protect the hydroxytrityl group-[1- 14 C]-2-bromoethanol reaction, the molecular weight of polyethylene glycol monomethyl ether mPEG is 350~20000. It should be noted that the corresponding hydroxytrityl protection-[1- 14 C]-2-bromoethanol polymerization degree, hydroxyl protection of different polymerization degrees [1- 14 C] The carbon-14 labeling site of polyethylene glycol monomethyl ether is always at the hydroxyl end.

[0037] In step S5, the fifth organic solvent is selected as one or any combination of tetrahydrofuran, methyltetrahydrofuran or diethyl ether, and the sixth organic solvent is selected as one or any combination of dichloromethane or ethyl acetate.

[0038] In step S5, polyethylene glycol monomethyl ether mPEG is dissolved in a fifth organic solvent and a hydroxytrityl-protected-[1- 14 C]-2-bromoethanol was reacted for 5-12 hours at a reaction temperature of 0-75°C. After the reaction was completed, water was added to quench the reaction. After the quenching was completed, the mixture was extracted with a sixth organic solvent, washed with saturated brine, dried, filtered, concentrated, and purified by rapid column chromatography to obtain hydroxyl-protected [1- 14 C] Polyethylene glycol monomethyl ether.

[0039] In one specific embodiment, the reaction equation of step S5 is as follows: .

[0040] Regarding the hydroxyl protection mentioned in step S5 [1- 14 C] The chemical formula of polyethylene glycol monomethyl ether is shown in the following formula (VI): .

[0041] Step S6 is to protect the hydroxyl group [1- 14C] polyethylene glycol monomethyl ether was subjected to hydroxyl deprotection reaction to obtain the final [1- 14 C] polyethylene glycol monomethyl ether. Hydroxyl protected [1 - 14C] polyethylene glycol monomethyl ether is used as the reaction substrate, and the hydrogen ion in the deprotecting agent attacks [1- 14 C] The oxygen atom in the ether bond of polyethylene glycol monomethyl ether causes the ether bond to break and the hydroxyl group to recover to generate [1- 14 C] Polyethylene glycol monomethyl ether.

[0042] In step S6, the seventh organic solvent is selected to be tetrahydrofuran or dichloromethane or any combination thereof.

[0043] In step S6, the deprotecting agent is trifluoroacetic acid.

[0044] In step S6, the hydroxyl group is protected [1- 14 C] Polyethylene glycol monomethyl ether is dissolved in the seventh organic solvent and a deprotecting agent is added to react for 2 to 12 hours at a reaction temperature of 0 to 25°C. After the reaction is completed, the seventh organic solvent is concentrated and purified by rapid column chromatography to obtain [1- 14 C] Polyethylene glycol monomethyl ether.

[0045] In one specific embodiment, the reaction equation of step S6 is as follows: .

[0046] Regarding [1- 14 C] The chemical formula of polyethylene glycol monomethyl ether is shown in formula (I): .

[0047] Compared with the prior art, this technical solution has the following characteristics and beneficial effects: The synthesis method of polyethylene glycol monomethyl ether labeled with radioisotope carbon-14 provided by this technical solution is universal, stable and economical. The overall synthesis method can synthesize polyethylene glycol monomethyl ether compounds with a specified degree of polymerization. The carbon-14 labeling site is always at the hydroxyl end, that is, carbon No. 1, which means that the polymer dispersion has basically not changed, and the labeled PEG has one more degree of polymerization of polyethylene glycol monomer than the original PEG. For high molecular weight PEG, the degree of polymerization is actually equivalent to maintaining consistency. The PEG polymerization degrees of PEG-modified drugs on the market are all different, with molecular weights ranging from 300Da-10000Kda. This solution can make various PEG-modified drugs accurately labeled with carbon-14PEG, and the key is to try to ensure that the carbon-14 labeled PEG fragment and the PEG in each specific PEG-modified drug maintain basically the same dispersion and degree of polymerization, thereby ensuring the accuracy of downstream kinetic studies or metabolic studies. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic diagram of the process of the traditional method for synthesizing carbon-14 labeled PEG.

[0049] Figure 2 According to an embodiment of the present invention, 14 C] Radiochemical purity chromatogram of polyethylene glycol monomethyl ether.

[0050] Figure 3 According to an embodiment of the present invention, 14 C] HPLC purity chromatogram of polyethylene glycol monomethyl ether.

[0051] Figure 4 is a hydroxytrityl protected-[1- 14 C] 1H-NMR spectrum of -2-bromoethanol.

[0052] Figure 5 is a hydroxyl protection according to one embodiment of the present invention [1- 14 C] 1H-NMR spectrum of polyethylene glycol monomethyl ether.

[0053] Figure 6 According to an embodiment of the present invention [1- 14 C] 1H-NMR spectrum of polyethylene glycol monomethyl ether. DETAILED DESCRIPTION

[0054] The following will be combined with the accompanying 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 belong to the scope of protection of the present invention.

[0055] The following examples are provided to illustrate the present invention. The examples are only used to further illustrate the present invention and do not represent the protection scope of the present invention. Non-essential modifications and adjustments made by others based on the present invention still fall within the protection scope of the present invention.

[0056] Step S1: Synthesis [1- 14 C] Acetic acid: ; Under negative pressure, 14 C-barium carbonate (398 mg, 2.0 mmol, 55 mCi / mmol) was added with concentrated sulfuric acid (10 mL) to generate 14C-carbon dioxide was passed into methylmagnesium bromide (3M / L in ether, 1.34 mL, 4.0 mmol, 2.0 eq) cooled in an ice-water bath, stirred for reaction for 1 hour, and then nitrogen was passed in and the reaction was continued for 1 hour. After the reaction was completed, 5% hydrochloric acid (5 mL) was added to quench the reaction, and ether was extracted 8 times, 5 mL each time. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated in an ice-water bath with a water pump to obtain a crude product [1- 14 C] acetic acid, the total activity of the crude product was 97.9 mCi, and the yield was about 89.0%. The crude product was directly used for the next step reaction.

[0057] Step S2: Synthesis [1- 14 C]-2-Bromoacetic acid: ; Crude product[1- 14 C] Acetic acid (97.9mCi, 1.78mmol) was placed in a sealed reactor under nitrogen protection and cooled in an ice-water bath. Trifluoroacetic anhydride (1.87g, 1.25ml, 5.0 eq) was first added dropwise. After addition, the mixture was kept warm for 10 minutes. Then, liquid bromine (0.28g, 1.78mmol, 0.9 mL, 1.0 eq) was added dropwise. After addition, the mixture was naturally heated to room temperature for 15 hours. After the reaction was completed, the reaction system changed from dark reddish brown to light reddish brown. The mixture was cooled in an ice-water bath, and 0.2mL of pure water was added dropwise. The mixture was stirred for 10 minutes and then quenched for 30 minutes. o C., concentrated under reduced pressure to remove the residual bromine and TFA, then added 30 mL of dichloromethane to dilute, added anhydrous sodium sulfate to dry directly for 1 hour, filtered, and 30 o C was concentrated under reduced pressure to remove the solvent to obtain a pale yellow crystalline solid crude product [1- 14 C]-2-bromoacetic acid, the total activity of the crude product is 80.6 mCi, the yield is 82.3%, and the crude product can be directly used for the next step reaction.

[0058] Step S3: Synthesis [1- 14 C]-2-bromoethanol: ; Under nitrogen atmosphere, the crude product [1- 14 C]-2-Bromoacetic acid (80.6 mCi, 1.47 mmol, 1.0 eq) was dissolved in 3 mL of anhydrous tetrahydrofuran and cooled to 0-5 °C in an ice-water bath. o C, add borane tetrahydrofuran solution (1M / L in THF, 4.4mL, 3.0 eq) dropwise, react at room temperature for 5 hours, and the reaction is complete. Cool in an ice-water bath, add 1mL of water dropwise, extract and stir for 30 minutes, add 25mL of dichloromethane to dilute, add anhydrous sodium sulfate to dry for 1 hour, filter, and 30 o C was concentrated under reduced pressure to remove the solvent to obtain a crude light yellow liquid [1-14 C]-2-bromoethanol, with a total activity of 80.5 mCi and a yield of 99.8%. The crude product was directly used for the next step reaction.

[0059] Step S4: Synthesis of trityl-protected [1- 14 C]-2-Bromoethanol-Otrt: ; Under nitrogen atmosphere, the crude product [1- 14 C]-2-bromoethanol (80.5 mCi, 1.47 mmol) was dissolved in 10 mL of dichloromethane, triethylamine (0.45 g, 4.4 mmol, 3.0 eq) was added, and the mixture was cooled to 0-5 °C in an ice-water bath. o C, then add triphenylmethyl chloride (0.614 g, 2.2 mmol, 1.5 eq), stir at room temperature for 15 hours, and the reaction is complete. Add dichloromethane and water, stir and stand to separate, wash the organic phase with water, dry it with anhydrous sodium sulfate for 1 hour, filter, concentrate, and separate and purify by rapid column chromatography (DCM:PE=1:50) to obtain a pure white solid product triphenylmethyl-protected [1- 14 C]-2-bromoethanol-OTrt, with a total activity of 64.2 mCi and a yield of 79.8%. 14 The 1H-NMR spectrum of C]-2-bromoethanol-Otrt is as follows Figure 4 As shown, it can be seen 1 H NMR (400 MHz, cdcl3) δ 7.47 (d, J = 7.4 Hz, 3H), 7.39 – 7.07 (m,6H), 3.43 (dq, J = 11.0, 5.6 Hz, 2H).

[0060] Step S4: Synthesis [1- 14 C]-mPEG-Otrt: ; Under nitrogen atmosphere, polyethylene glycol monomethyl ether 1000 (mPEG-OH, mw = 1000Da, 1.17g, 1.17mmol, 1.0eq) was added to 20mL of anhydrous tetrahydrofuran and stirred until completely dissolved, then cooled to 0-5℃ in an ice-water bath. o C, add sodium hydride (60% in mineral, 0.14 g, 3.5 mmol, 3.0 eq), keep in ice bath for 30 minutes, then add condenser and heat to 75 oC, refluxed for 8 hours, and the reaction was completed. 10 mL of saturated ammonium chloride solution was added to extract and quenched, and dichloromethane was extracted three times, the dichloromethane was combined, and the mixture was washed once with saturated brine, dried over anhydrous sodium sulfate for 1 hour, filtered, concentrated, and purified by rapid column chromatography (MeOH:DCM=1:30) to obtain an off-white solid product [1- 14 C]-mPEG-OTrt, total activity 54.1 mCi, yield 84.3%, [1- 14 The 1H-NMR spectrum of C]-mPEG-Otrt is shown in Figure 5 As shown, it can be seen 1 H NMR (400MHz, cdcl3) δ 7.51 – 7.16 (m, 10H), 3.65 (d, J = 11.2 Hz, 47H), 3.37 (s, 2H).

[0061] Step S6: Synthesis [1- 14 C]-mPEG-OH: ; Under nitrogen atmosphere, [1- 14 C]-mPEG-OTrt (54.1 mCi) was dissolved in 10 mL of dichloromethane and cooled to 0-5 °C in an ice-water bath. o C, add 4 mL of trifluoroacetic acid, stir at room temperature for 12 hours, and the reaction is completed. Most of the solvent and trifluoroacetic acid are concentrated under reduced pressure, then dilute with dichloromethane, adjust the pH to 8-9 with saturated sodium bicarbonate solution, separate the layers, extract the aqueous phase twice with dichloromethane, combine the organic phases, dry over anhydrous sodium sulfate for 1 hour, filter, concentrate, and separate and purify by rapid column chromatography to obtain a white solid product [1- 14 C]-mPEG-OH, total activity 47.8 mCi, chemical purity and radiochemical purity are both about 98%. [1- 14 The 1H-NRM spectrum of C]-mPEG-OH is shown in Figure 6 As shown, it can be seen 1 H NMR (400 MHz, cdcl3) δ 3.90 – 3.39 (m, 132H), 3.35 (s, 5H), 2.71 (s, 3H).

[0062] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14, characterized in that: The following steps are involved: S1: Synthesis [1- 14 C] Acetic acid: Under negative pressure, 14 C-barium carbonate is added with concentrated acid to generate 14 C-carbon dioxide, 14 C-carbon dioxide is introduced into the methylmagnesium bromide solution to react and pass an inert gas. After the reaction is completed, dilute acid is added to quench, and then the organic phases are combined after multiple extractions with an organic solvent, dried, filtered, and the solvent is distilled off at normal pressure to obtain [1- 14 C] acetic acid; S2: Synthesis [1- 14 C]-2-Bromoacetic acid: Stored in sealed reactor [1- 14 C] acetic acid and trifluoroacetic anhydride are added, followed by the addition of a bromination reagent for reaction, after which water is added to quench and concentrate, followed by dilution with an organic solvent, drying, filtering, and concentrating to obtain [1- 14 C]-2-bromoacetic acid; S3: Synthesis [1- 14 C]-2-bromoethanol: Under inert gas protection, [1- 14 C]-2-bromoacetic acid is dissolved in the first organic solvent and a reducing agent is added to react. After the reaction is completed, water is added to quench the reaction, followed by dilution with a second organic solvent, drying, filtering, and concentration to obtain [1- 14 C]-2-bromoethanol; S4: Synthesis of hydroxytrityl-protected-[1- 14 C]-2-bromoethanol: Under inert gas protection, [1- 14 C]-2-bromoethanol is dissolved in a third organic solvent, an organic base and a hydroxyl protecting agent are added to react, water is added to quench after the reaction is completed, and then extracted with a fourth organic solvent, washed with water, dried, filtered, concentrated, and separated by rapid column chromatography to obtain hydroxytrityl-protected-[1- 14 C]-2-bromoethanol; S5: Synthesis of Hydroxyl Protected [1- 14 C] Polyethylene glycol monomethyl ether: Under the protection of inert gas, polyethylene glycol monomethyl ether mPEG is dissolved in the fifth organic solvent and hydroxytrityl-protected-[1- 14 C]-2-bromoethanol reaction, after the reaction is completed, water is added to quench, after the quenching is completed, extraction is performed with a sixth organic solvent, washing with saturated brine, drying, filtering, concentrating, and rapid column chromatography separation and purification are performed to obtain hydroxyl-protected [1- 14 C] Polyethylene glycol monomethyl ether; S6: Synthesis [1- 14 C] Polyethylene glycol monomethyl ether: The hydroxyl group is protected [1- 14 C] polyethylene glycol monomethyl ether is dissolved in the seventh organic solvent and a deprotecting agent is added to react. After the reaction is completed, the seventh organic solvent is concentrated and purified by rapid column chromatography to obtain [1- 14 C] Polyethylene glycol monomethyl ether.

2. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioisotope carbon-14 according to claim 1, characterized in that: In step S1, the concentrated acid is selected from phosphoric acid, sulfuric acid, hydrochloric acid or any combination thereof, and the organic solvent is selected from dichloromethane and ether or any combination thereof.

3. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14 according to claim 1, characterized in that: In step S2, the bromination reagent is liquid bromine, and the organic solvent is dichloromethane or ether or any combination thereof.

4. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14 according to claim 1, characterized in that: In step S3, the first organic solvent is selected as one or any combination of tetrahydrofuran or diethyl ether, the second organic solvent is selected as one or any combination of dichloromethane or diethyl ether, and the reducing agent is selected as one or any combination of borane tetrahydrofuran or borane dimethyl sulfide.

5. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioisotope carbon-14 according to claim 1, characterized in that: In step S4, the third organic solvent is selected as one or any combination of tetrahydrofuran, dichloromethane or diethyl ether, the fourth organic solvent is selected as one or any combination of dichloromethane or ethyl acetate, the organic base is selected as one or any combination of triethylamine, diisopropylethylamine or imidazole, and the hydroxyl protecting agent is selected as triphenylmethyl chloride.

6. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioisotope carbon-14 according to claim 1, characterized in that: In step S5, the fifth organic solvent is selected as one or any combination of tetrahydrofuran, methyltetrahydrofuran or diethyl ether, and the sixth organic solvent is selected as one or any combination of dichloromethane or ethyl acetate.

7. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14 according to claim 1, characterized in that: The seventh organic solvent is selected as tetrahydrofuran or dichloromethane or any combination thereof, and the deprotecting agent is selected as trifluoroacetic acid.

8. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioisotope carbon-14 according to claim 1, characterized in that: In step S5, polyethylene glycol monomethyl ether mPEG with different polymerization degrees is selected to protect the hydroxytrityl group-[1- 14 C]-2-bromoethanol reaction, the molecular weight of polyethylene glycol monomethyl ether mPEG is 350~20000.

9. The method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14 according to claim 8, characterized in that: Hydroxyl protection with different polymerization degrees [1- 14 C] The carbon-14 labeling site of polyethylene glycol monomethyl ether is always at the hydroxyl end.

10. A radioactive isotope carbon-14 labeled polyethylene glycol monomethyl ether, characterized in that: According to the synthesis method of any one of claims 1 to 9, the synthesized [1- 14 C] The chemical formula of polyethylene glycol monomethyl ether is shown in formula (I): 。

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