A method for synthesizing a radioisotope carbon-14 labeled polyethylene glycol monomethyl ether

Abstract

The scheme provides a synthesis method of a radioisotope carbon-14 labeled polyethylene glycol monomethyl ether, comprising steps: S1: synthesis of [1- 14 C] acetic acid; S2: synthesis of [1- 14 C]-2-bromoacetic acid; S3: synthesis of [1- 14 C]-2-bromoethanol; S4: synthesis of hydroxytriphenylmethyl protected-[1- 14 C]-2-bromoethanol; S5: synthesis of hydroxyl protected [1- 14 C] polyethylene glycol monomethyl ether; S6: synthesis of [1- 14 C] polyethylene glycol monomethyl ether, the overall synthesis method is general, stable and economical, and can synthesize polyethylene glycol monomethyl ether compounds with specified polymerization degree. The carbon-14 labeled polyethylene glycol monomethyl ether is an important intermediate for synthesis of PEG of different polymers, is used for carbon 14-labeled PEG modification of various small molecule drugs, and is used as a tracer for performance research of the PEG modified drugs in pharmacokinetics and other aspects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of radiochemical synthesis, and particularly relates to a synthesis method of a radioisotope carbon-14 labeled polyethylene glycol monomethyl ether. BACKGROUND

[0002] Polyethylene glycol (PEG) is a high molecular polymer obtained by the step-by-step addition polymerization of ethylene oxide and water or ethylene glycol. When polyethylene glycol is combined with biological materials, its "stealth" effect is mainly derived 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, so that polyethylene glycol has good hydrophilicity. In the body, a layer of hydration layer can be formed on the surface of the polyethylene glycol chain, which acts as a "protective cover" to prevent the non-specific adsorption of biological macromolecules such as proteins on the material surface. For example, in a drug delivery system, if the surface of the nanometer drug carrier is modified with polyethylene glycol, the adsorption of plasma proteins can be reduced, thereby avoiding recognition and removal by the mononuclear phagocyte system, prolonging the circulation time of the drug in the body. This characteristic of reducing the non-specific interaction between biological materials and components in the body is called "stealth" effect. Because of this characteristic, polyethylene glycol is widely regarded as a "gold standard" of biological materials in the biomedical field.

[0003] With the deepening of research, the development technology of PEG modified drugs is constantly improving, and many PEG modified drugs have been approved for marketing by FDA and other drug regulatory departments. The emergence of more and more PEG modified drugs means that various pharmacokinetic and other performance studies exist for these PEG modified drugs, which means that the demand for carbon-14 labeled PEG will be more and more. So far, there are not many literatures about the synthesis method of carbon-14 labeled PEG. In 2007, Gary Shemilt et al. reported a method for synthesizing carbon-14 labeled PEG. The method generates a sodium salt of PEG and then reacts with a double-labeled ethylene oxide to obtain a carbon-14 labeled polyethylene glycol polymer. The reaction route and possible impurities are shown in Figure 1 However, this method has many defects. From the experimental data, it can be known that there are small molecule labeled fragment impurities in the synthesized polymer, which are caused by the initiation of double-labeled ethylene oxide to form oligomers. In addition, the dispersity of the overall labeled product is significantly increased, and it is difficult to precisely control the reaction of the polymer only with one labeled monomer, which is difficult to meet the strict requirements of different PEG modified drugs on the dispersity and molecular weight of PEG fragments.

[0004] Considering that the dispersity 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 dispersity and molecular weight of each PEG-modified drug as much as possible. Summary of the Invention

[0005] The present invention aims to provide a method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14. Carbon-14-labeled polyethylene glycol monomethyl ether is synthesized. The carbon-14-labeled polyethylene glycol monomethyl ether serves as an important intermediate for synthesizing PEG of different polymers and is used for carbon-14-labeled PEG modification of various small molecule drugs, thereby serving as a tracer for studying the pharmacokinetic and other performance aspects of the PEG-modified drugs.

[0006] To achieve the above objectives, the present technical solution provides a method for synthesizing polyethylene glycol monomethyl ether labeled with radioactive isotope carbon-14, comprising the following steps:

[0007] S1: Synthesis [1- 14 C] Acetic acid:

[0008] 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 methylmagnesium bromide solution to react and pass inert gas. After the reaction is completed, dilute acid is added to quench the reaction. The organic phases are then extracted several times with an organic solvent, combined, dried, filtered, and the solvent is distilled off under normal pressure to obtain [1- 14 C] acetic acid;

[0009] S2: Synthesis [1- 14 C]-2-bromoacetic acid:

[0010] Stored in sealed reactor [1- 14 C] acetic acid and trifluoroacetic anhydride, followed by the addition of a brominating agent to react, and after the reaction is complete, 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;

[0011] S3: Synthesis [1- 14 C]-2-bromoethanol:

[0012] Under the protection of inert gas, [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, and then the mixture is diluted with a second organic solvent, dried, filtered, and concentrated to obtain [1- 14 C]-2-bromoethanol;

[0013] S4: Synthesis of hydroxyl trityl protected-[1- 14 C]-2-bromoethanol

[0014] S3: Synthesis of hydroxyl trityl protected-[1- 14 C]-2-bromoethanol 14 C]-2-bromoethanol is obtained by dissolving [1-

[0015] S5: Synthesis of hydroxyl protected [1- 14 C] polyethylene glycol monomethyl ether

[0016] S4: Synthesis of hydroxyl trityl protected-[1- 14 C]-2-bromoethanol 14 C] polyethylene glycol monomethyl ether is obtained by dissolving hydroxyl protected [1-

[0017] S6: Synthesis of [1- 14 C] polyethylene glycol monomethyl ether

[0018] S5: Synthesis of hydroxyl protected [1- 14 C] polyethylene glycol monomethyl ether 14 C] polyethylene glycol monomethyl ether is obtained by dissolving hydroxyl protected [1-

[0019] The synthesis method of the radioisotope carbon-14 labeled polyethylene glycol monomethyl ether proposed in the scheme uses 14 C-barium carbonate as a radioisotope raw material, which is converted 14 C-carbon dioxide, and reacts with methyl magnesium bromide Grignard reagent to obtain [1- 14 C]-acetic acid, then reacts with trifluoroacetic anhydride and liquid bromine to generate [1- 14 C]-2-bromoacetic acid, 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, then reacts with mPEG of different polymerization degrees to generate hydroxyl protected [1- 14 C]-polyethylene glycol monomethyl ether, and then reacts with a hydroxyl deprotection agent to obtain [1- 14C] - polyethylene glycol monomethyl ether, the specific activity of the final product: 1.0 ~ 10 mCi / g; both chemical purity and radiochemical purity are greater than 98%.

[0020] Specifically:

[0021] Regarding step S1: with 14 C-barium carbonate as a radioisotope raw material, is the key starting material for introducing carbon-14 labeling, which will be converted to 14 C-carbon dioxide in subsequent reactions, and then participate in the reaction, methyl magnesium bromide solution is Grignard reagent, which provides carbon anion for nucleophilic addition reaction with 14 C-carbon dioxide to obtain [1- 14 C]-acetic acid.

[0022] The reaction of step S1 of the present scheme is carried out under negative pressure, which helps to promote 14 C-carbon dioxide to be released from 14 C-barium carbonate and smoothly enter the methyl magnesium bromide solution to participate in the reaction, and inert gas needs to be introduced to remove oxygen and moisture in the reaction system, and inert gas protection can ensure that the reaction proceeds smoothly in a water-free and oxygen-free environment.

[0023] In step S1, the concentrated acid is selected as one or any combination of phosphoric acid, sulfuric acid, and hydrochloric acid.

[0024] In step S1, the organic solvent is selected from one or any combination of dichloromethane and diethyl ether.

[0025] In step S1, concentrated acid is added to 14 C-barium carbonate to generate 14 C-carbon dioxide, and 14 C-carbon dioxide is introduced into the methyl magnesium bromide solution for reaction and inert gas is introduced, the reaction is carried out for 1-3 h, and the reaction temperature is set to 0-25℃, after the reaction is completed, dilute acid is added for quenching, then the organic phase is combined after extraction with organic solvent for multiple times, dried, filtered, and the solvent is distilled out at normal pressure to obtain [1- 14 C] acetic acid.

[0026] In a specific embodiment, the reaction equation of step S1 is as shown below:

[0027] .

[0028] Regarding [1- 14 C] acetic acid mentioned in step S1, the chemical formula is as shown in formula (II) below, wherein the asterisk indicates the labeling position of carbon-14:

[0029] .

[0030] As to step S2, [1- 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 strong acylating ability and can convert the carboxyl group of acetic acid into a more active acyl group, which is conducive to the subsequent introduction of bromine atoms. The brominating agent is a source of bromine atoms and is used to carry out bromination on the acylated intermediate.

[0031] Step S2 of the present scheme is carried out in a sealed reactor to avoid the volatilization of trifluoroacetic anhydride and the brominating agent into the air, which can cause loss of raw materials, environmental pollution, and harm to operators.

[0032] In step S2, the brominating agent is selected as liquid bromine.

[0033] In step S2, the organic solvent is selected as one or any combination of dichloromethane or diethyl ether.

[0034] In step S2, [1- 14 C] acetic acid is stored in a sealed reactor and trifluoroacetic anhydride is added, followed by the addition of the brominating agent. The reaction is carried out for 12-20 h at a reaction temperature of 0-25°C. After the reaction is completed, water is added to quench the reaction and concentrated. Then, the reaction mixture is diluted with an organic solvent, dried, filtered, and concentrated to obtain [1- 14 C]-2-bromoacetic acid.

[0035] In a specific embodiment, the reaction equation of step S2 is as follows:

[0036] .

[0037] The chemical formula of [1- 14 C]-2-bromoacetic acid synthesized in step S2 is shown in the following formula (III):

[0038] .

[0039] In step S3, [1- 14 C]-2-bromoacetic acid is used as a reaction material and reacts with a reducing agent. The reducing agent reduces the carboxyl group in [1- 14 C]-2-bromoacetic acid to a hydroxyl group while having little effect on the bromine atoms in the molecule. The reaction is carried out under inert gas protection to prevent oxygen and moisture from entering the reaction system.

[0040] In step S3, the first organic solvent is selected as one or any combination of tetrahydrofuran or diethyl ether. Anhydrous solvent can avoid the interference of water to the reaction, and ether solvents such as tetrahydrofuran have good solubility to reactants and products, which can make the reaction proceed smoothly.

[0041] In step S3, the reducing agent is selected as one or any combination of borane tetrahydrofuran or borane dimethyl sulfide, and the borane reducing agent has strong reducing property and can selectively reduce the carboxyl group to hydroxyl group while having little effect on the bromine atom in the molecule.

[0042] In step S3, the second organic solvent is selected as one or any combination of dichloromethane or diethyl ether.

[0043] In step S3, [1- 14 C]-2-bromoacetic acid is dissolved in the first organic solvent and the reducing agent is added and reacted for 2-5 hours at a reaction temperature of 0-25°C. After the reaction is completed, water is added to quench the reaction, and then the second organic solvent is used for dilution, drying, filtration and concentration to obtain [1- 14 C]-2-bromoethanol.

[0044] In a specific embodiment, the reaction equation of step S3 is as shown below:

[0045] .

[0046] The chemical formula of [1- 14 C]-2-bromoethanol in step S3 is as shown in formula (IV) below:

[0047] .

[0048] In step S4, the hydroxyl group of [1- 14 C]-2-bromoethanol is protected to form hydroxytriphenylmethyl-protected-[1- 14 C]-2-bromoethanol. The hydroxyl protecting agent reacts with the hydroxyl group of [1- 14 C]-2-bromoethanol to form a stable ether bond, which protects the hydroxyl group from interference in subsequent reactions. The organic base neutralizes the hydrogen chloride produced during the reaction to facilitate the reaction to proceed to the right.

[0049] In step S4, the third organic solvent is selected as one or any combination of tetrahydrofuran, dichloromethane or diethyl ether, and the fourth organic solvent is selected as one or any combination of dichloromethane or ethyl acetate.

[0050] In step S4, the organic base is selected as one or any combination of triethylamine, diisopropyl ethylamine or imidazole.

[0051] In step S4, the hydroxyl protecting agent is selected as triphenylmethyl chloride. The organic base reacts with triphenylmethyl chloride to form triphenylmethyl cation and chloride ion. The triphenylmethyl cation has high electrophilicity and forms a positively charged intermediate with the oxygen atom on the hydroxyl group of [1- 14 C]-2-bromoethanol. Subsequently, the intermediate loses a proton to form hydroxytriphenylmethyl-protected-[1-14 C]-2-bromoethanol.

[0052] In a specific embodiment, the reaction equation of step S4 is as follows:

[0053] .

[0054] Regarding the hydroxy trityl protection-[1- 14 C]-2-bromoethanol, the chemical formula is shown in the following formula (V):

[0055] .

[0056] Step S5 is a nucleophilic substitution reaction of hydroxy trityl protection-[1- 14 C]-2-bromoethanol with polyethylene glycol monomethyl ether of different polymerization degrees to generate hydroxy protection[1- 14 C]polyethylene glycol monomethyl ether, hydroxy trityl protection-[1- 14 C]-2-bromoethanol as an electrophile in the nucleophilic substitution reaction, provides carbon-14 labeling and the part to be connected to polyethylene glycol monomethyl ether. Polyethylene glycol monomethyl ether of different polymerization degrees as a nucleophile, the oxygen atom at the hydroxyl end has nucleophilicity and can attack the electrophile to occur nucleophilic substitution reaction.

[0057] In step S5, polyethylene glycol monomethyl ether mPEG of different polymerization degrees is selected to react with hydroxy trityl protection-[1- 14 C]-2-bromoethanol, and the molecular weight of polyethylene glycol monomethyl ether mPEG is 350-20000. It should be noted that the polymerization degree of hydroxy trityl protection-[1- 14 C]-2-bromoethanol is selected according to the actual labeling requirements, and the carbon-14 labeling site of hydroxy protection[1- 14 C]polyethylene glycol monomethyl ether is always at the hydroxyl end.

[0058] In step S5, the fifth organic solvent is selected as one or any combination of tetrahydrofuran, methyl tetrahydrofuran or diethyl ether, and the sixth organic solvent is selected as one or any combination of dichloromethane or ethyl acetate.

[0059] In step S5, polyethylene glycol monomethyl ether mPEG is dissolved in the fifth organic solvent and hydroxy trityl protection-[1- 14 C]-2-bromoethanol is added for reaction for 5-12 hours, and the reaction temperature is 0-75°C. After the reaction is completed, water is added for quenching, and after the quenching is completed, the sixth organic solvent is extracted, saturated brine is washed, dried, filtered, concentrated, and separated and purified by flash column chromatography to obtain hydroxy protection[1- 14 C]polyethylene glycol monomethyl ether.

[0060] In a specific embodiment, the reaction equation of step S5 is as follows:

[0061] .

[0062] Regarding the hydroxyl protection mentioned in step S5, the chemical formula of the hydroxyl-protected [1- 14 C] polyethylene glycol monomethyl ether is as shown in formula (VI):

[0063] .

[0064] Step S6 is a hydroxyl deprotection reaction of the hydroxyl-protected [1- 14 C] polyethylene glycol monomethyl ether to obtain the final [1- 14 C] polyethylene glycol monomethyl ether with different polymerization degrees. The hydrogen ion in the deprotection agent attacks the oxygen atom in the ether bond of the [1- 14 C] polyethylene glycol monomethyl ether, causing the ether bond to break and the hydroxyl group to recover, to generate the [1- 14 C] polyethylene glycol monomethyl ether.

[0065] In step S6, the seventh organic solvent is selected as one or any combination of tetrahydrofuran or dichloromethane.

[0066] In step S6, the deprotection agent is selected as trifluoroacetic acid.

[0067] In step S6, the hydroxyl-protected [1- 14 C] polyethylene glycol monomethyl ether is dissolved in the seventh organic solvent and the deprotection agent is added and reacted for 2-12 h, the reaction temperature is 0-25℃, after the reaction is completed, the seventh organic solvent is concentrated and fast column chromatography is used for separation and purification to obtain the [1- 14 C] polyethylene glycol monomethyl ether.

[0068] In a specific embodiment, the reaction equation of step S6 is as follows:

[0069] .

[0070] Regarding the [1- 14 C] polyethylene glycol monomethyl ether involved in step S6, the chemical formula is as shown in formula (I):

[0071] .

[0072] Compared with the prior art, the technical scheme has the following characteristics and beneficial effects:

[0073] The present technical solution provides a synthesis method for radioisotope carbon-14 labeled polyethylene glycol monomethyl ether. The overall synthesis method is universal, stable, and economical. It 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 position 1, which means that the polymer dispersion is basically unchanged, while the labeled PEG has an additional degree of polymerization of one polyethylene glycol monomer compared to the original PEG. For high-molecular-weight PEG, the degree of polymerization is actually equivalent to maintaining consistency. Currently, the PEG polymerization degrees of PEG-modified drugs on the market are all different, with molecular weights ranging from 300Da to 10,000KDa. This solution allows various PEG-modified drugs to be precisely labeled with carbon-14PEG. The key is to ensure that the carbon-14 labeled PEG fragment maintains a basically consistent dispersion and degree of polymerization with the PEG in each specific PEG-modified drug, thereby ensuring the accuracy of downstream kinetic or metabolic studies. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 This is a schematic diagram of the traditional method for synthesizing carbon-14 labeled PEG.

[0075] Figure 2 According to one embodiment of the present invention [1- 14 C] Radiochemical purity chromatogram of polyethylene glycol monomethyl ether.

[0076] Figure 3 According to one embodiment of the present invention [1- 14 C] HPLC purity chromatogram of polyethylene glycol monomethyl ether.

[0077] Figure 4 According to one embodiment of the present invention, the hydroxytrityl-protected 14 C] 1H-NMR spectrum of 2-bromoethanol.

[0078] 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.

[0079] Figure 6 According to an embodiment of the present invention [1- 14 C] 1H-NMR spectrum of polyethylene glycol monomethyl ether. DETAILED DESCRIPTION

[0080] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application belong to the scope of protection of the present application.

[0081] The present application is described below by means of the following illustrative examples. The examples are only used to further illustrate the present application, and do not represent the protection scope of the present application. Non-essential modifications and adjustments made by others according to the present application still belong to the protection scope of the present application.

[0082] Step S1: synthesis of [1- 14 C] acetic acid:

[0083] ;

[0084] Under negative pressure, 14 C-Barium carbonate (398 mg, 2.0 mmol, 55 mCi / mmol) was added with concentrated sulfuric acid (10 mL), and the generated 14 C-Carbon dioxide was passed into methyl magnesium bromide (3M / L in ether, 1.34 mL, 4.0mmol, 2.0 eq) cooled in an ice water bath, and after stirring for 1 hour, 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 the organic phase was extracted with 5 mL of ether 8 times, dried over anhydrous sodium sulfate, filtered, and concentrated by water pump in an ice water bath to obtain the crude [1- 14 C] acetic acid, with a total activity of 97.9 mCi and a yield of about 89.0%. The crude product was directly used in the next step.

[0085] Step S2: synthesis of [1- 14 C]-2-bromoacetic acid:

[0086] ;

[0087] The crude [1- 14 C] acetic acid (97.9 mCi, 1.78 mmol) was cooled in an ice water bath in a sealed reactor under nitrogen protection, and trifluoroacetic anhydride (1.87 g, 1.25 ml, 5.0 eq) was first added dropwise, and after the addition was completed, the reaction was allowed to react for 10 minutes, and then liquid bromine (0.28 g, 1.78 mmol, 0.9 mL, 1.0 eq) was added dropwise, and after the addition was completed, the reaction was allowed to react at room temperature for 15 hours. After the reaction was completed, the reaction system changed from deep red-brown to light red-brown, and 0.2 mL of pure water was added dropwise under ice water bath cooling, and the reaction was quenched and extracted by stirring for 10 minutes. The organic phase was extracted with 30 oC, and then added with dichloromethane 30 mL for dilution, added with anhydrous sodium sulfate for direct drying 1 hour, filtered, 30 o C, and then added with dichloromethane 30 mL for dilution, added with anhydrous sodium sulfate for direct drying 1 hour, filtered, 30 14 C, and then added with dichloromethane 30 mL for dilution, added with anhydrous sodium sulfate for direct drying 1 hour, filtered, 30

[0088] Step S3: synthesis of [1- 14 C]-2-bromoethanol:

[0089] ;

[0090] The crude [1- 14 C]-2-bromoacetic acid (80.6 mCi, 1.47 mmol, 1.0 eq) was dissolved in anhydrous tetrahydrofuran 3 mL, and cooled to 0~5 o C, and then added with dichloromethane 30 mL for dilution, added with anhydrous sodium sulfate for direct drying 1 hour, filtered, 30 o C, and then added with dichloromethane 30 mL for dilution, added with anhydrous sodium sulfate for direct drying 1 hour, filtered, 30 14 C]-2-bromoethanol, total activity 80.5 mCi, yield 99.8%, and the crude product was directly used for the next reaction.

[0091] Step S4: synthesis of triphenylmethyl-protected [1- 14 C]-2-bromoethanol-Otrt:

[0092] ;

[0093] The crude [1- 14 C]-2-bromoethanol (80.5 mCi, 1.47 mmol) was dissolved in dichloromethane 10 mL, added with triethylamine (0.45 g, 4.4 mmol, 3.0 eq), cooled to 0~5 o C, and then added with dichloromethane 30 mL for dilution, added with anhydrous sodium sulfate for direct drying 1 hour, filtered, 30 14C]-2-bromoethanol-OTrt, total activity 64.2 mCi, yield 79.8%. The synthesis of triphenylmethyl protected [1- 14 The1H-NMR spectrum of C]-2-bromoethanol-OTrt is shown in Figure 4 Figure 2, which shows 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)。

[0094] Step S4: synthesis of [1- 14 C]-mPEG-OTrt:

[0095] ;

[0096] Under the protection of nitrogen atmosphere, polyethylene glycol monomethyl ether 1000 (mPEG-OH, m.w=1000 Da, 1.17 g, 1.17 mmol, 1.0 eq) was added into anhydrous tetrahydrofuran 20 mL and stirred until completely dissolved, then cooled to 0~5 o C, sodium hydride (60% in mineral, 0.14 g, 3.5 mmol, 3.0 eq) was added, and the ice bath was kept for 30 minutes, then a condenser was added, and heated to 75 o C for 8 hours. After the reaction was completed, saturated ammonium chloride solution 10 mL was added for extraction, dichloromethane was extracted 3 times, the dichloromethane was combined, washed with saturated brine once, dried with anhydrous sodium sulfate for 1 hour, filtered, concentrated, and purified by flash column chromatography (MeOH:DCM=1:30) to obtain a white solid product [1- 14 C]-mPEG-OTrt, total activity 54.1 mCi, yield 84.3%, [1- 14 The1H-NMR spectrum of C]-mPEG-OTrt is shown in Figure 5 Figure 3, which shows 1 H NMR (400MHz, cdcl3) δ 7.51 – 7.16 (m, 10H), 3.65 (d, J = 11.2 Hz, 47H), 3.37 (s, 2H)。

[0097] Step S6: synthesis of [1- 14 C]-mPEG-OH:

[0098] ;

[0099] [1- 14 C]-mPEG-OTrt (54.1 mCi) was dissolved in 10 mL of dichloromethane, and cooled to 0-5 o C, and 4 mL of trifluoroacetic acid was added. After the addition, the reaction was stirred at room temperature for 12 hours. After the reaction was completed, most of the solvent and trifluoroacetic acid were removed under reduced pressure, and then dichloromethane was added for dilution. The pH was adjusted to 8-9 with a saturated sodium bicarbonate solution, and the layers were separated. The aqueous phase was extracted twice with dichloromethane, and the combined organic phase was dried over anhydrous sodium sulfate for 1 hour, filtered, concentrated, and purified by flash column chromatography to obtain the product [1- 14 C]-mPEG-OH as a white solid, with a total activity of 47.8 mCi and a chemical purity and radiochemical purity of about 98%. 14 The 1H-NMR spectrum of [1- Figure 6 C]-mPEG-OH is shown in FIG. 1, and it can be seen that 1 H NMR (400 MHz, cdcl3) δ 3.90 – 3.39(m, 132H), 3.35 (s, 5H), 2.71 (s, 3H).

[0100] The present application is not limited to the above-described best mode, and anyone can derive other various forms of products under the inspiration of the present application, but regardless of any changes in shape or structure, any technical solution having the same or similar technical solution as the present application falls within the scope of the present application.

Claims

1. A method for the synthesis of a radioisotope carbon-14 labeled polyethylene glycol monomethyl ether, characterized in that, The method comprises the following steps: S1 : Synthesis of [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 methylmagnesium bromide solution to react and pass inert gas. After the reaction is completed, dilute acid is added to quench the reaction. The organic phases are then extracted several times with an organic solvent, combined, dried, filtered, and the solvent is distilled off under normal pressure to obtain [1- 14 C] acetic acid; S2: Synthesis of [1- 14 C]-2-bromoacetic acid: In a sealed reactor was placed [1- 14 C] acetic acid and a brominating reagent was added, followed by the addition of trifluoroacetic anhydride. The reaction was quenched with water, concentrated, and then diluted with an organic solvent, dried, filtered, and concentrated to yield [1- 14 C]-2-bromoacetic acid; S3: Synthesis of [1- 14 C]-2-bromoethanol: [1- 14 C]-2-bromoethanol; wherein the first organic solvent is selected from one or any combination of tetrahydrofuran or diethyl ether, the second organic solvent is selected from one or any combination of dichloromethane or diethyl ether, and the reducing agent is selected from one or any combination of borane tetrahydrofuran or borane dimethyl sulfide; and 14 C]-2-bromoethanol; wherein the first organic solvent is selected from one or any combination of tetrahydrofuran or diethyl ether, the second organic solvent is selected from one or any combination of dichloromethane or diethyl ether, and the reducing agent is selected from one or any combination of borane tetrahydrofuran or borane dimethyl sulfide; and S4: Synthesis of hydroxy trityl protected-[1- 14 C]-2-bromoethanol: [1- 14 C]-2-bromoethanol is dissolved in a third organic solvent, an organic base and a hydroxyl protecting agent are added, and the reaction is carried out under inert gas protection. After the reaction is completed, water is added for quenching, followed by extraction with a fourth organic solvent, washing with water, drying, filtration, concentration, and separation by flash column chromatography to obtain the hydroxyl triphenylmethyl-protected [1- 14 C]-2-bromoethanol; in step S4, the third organic solvent is selected from one or any combination of tetrahydrofuran, dichloromethane or diethyl ether, the fourth organic solvent is selected from one or any combination of dichloromethane or ethyl acetate, the organic base is selected from one or any combination of triethylamine, diisopropylethylamine or imidazole, and the hydroxyl protecting agent is selected from triphenylmethyl chloride; 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 reacted with hydroxy trityl protected-[1- 14 C]-2-bromoethanol, water is added after the reaction is completed, the quenching is completed, extracted with the sixth organic solvent, washed with saturated brine, dried, filtered, concentrated, separated and purified by flash column chromatography to obtain hydroxy protected-[1- 14 C] polyethylene glycol monomethyl ether; in step S5, polyethylene glycol monomethyl ether mPEG with different polymerization degrees is selected to react with hydroxy trityl protected-[1- 14 C]-2-bromoethanol, the molecular weight of polyethylene glycol monomethyl ether mPEG is 350-20000; S6: Synthesis of [1- 14 C] Polyethylene glycol monomethyl ether: dissolved in a seventh organic solvent and reacted with a deprotection agent, after the reaction, the seventh organic solvent was concentrated and purified by flash column chromatography to obtain [1- 14 C] polyethylene glycol monomethyl ether. 14 C] polyethylene glycol monomethyl ether.

2. The method of synthesis of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether according to claim 1, characterized in that, In step S1, the concentrated acid is selected as one or any combination of phosphoric acid, sulfuric acid, and hydrochloric acid, and the organic solvent is selected as one or any combination of dichloromethane and diethyl ether.

3. The method of synthesis of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether according to claim 1, wherein, In step S2, the bromination reagent is selected as liquid bromine, and the organic solvent is selected as one or any combination of dichloromethane and diethyl ether.

4. The method of synthesis of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether according to claim 1, wherein, In step S5, the fifth organic solvent is selected as one or any combination of tetrahydrofuran, methyl tetrahydrofuran, and diethyl ether, and the sixth organic solvent is selected as one or any combination of dichloromethane and ethyl acetate.

5. The method of synthesis of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether according to claim 1, wherein, The seventh organic solvent is selected as one or any combination of tetrahydrofuran and dichloromethane, and the deprotection agent is selected as trifluoroacetic acid.

6. The method of synthesis of radioisotope carbon-14 labeled polyethylene glycol monomethyl ether according to claim 1, wherein, Hydroxyl protection of different degrees of polymerization 14 C] The carbon-14 labeling site of the polyethylene glycol monomethyl ether is always at the hydroxyl end.

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