Preparation method and application of 14C-labeled 4-dihydroxyboryl phenylalanine

Abstract

The invention provides a preparation method and application of 14C-labeled 4-dihydroxyboryl phenylalanine, and belongs to the technical field of synthesis of carbon isotope markers. According to the method, 14C-labeled aniline is used as a starting material, firstly, 14C-aniline and acrylonitrile are in butt joint through diazotization reaction, then cyano is hydrolyzed to obtain corresponding carboxylic acid, and ammonia water is used for converting chlorine in molecules into amino to obtain 14C-phenylalanine. The method comprises the following steps: carrying out chiral column separation on 14C-phenylalanine to obtain levo 14C-phenylalanine, and carrying out four-step reaction on the levo 14C-phenylalanine to synthesize the 14C-BPA. According to the method, commercially available 14C-aniline is used as a raw material, and the 14C-BPA is efficiently synthesized through seven-step reaction. And the product purity is high and is greater than 99%.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon isotope label synthesis and mainly relates to a 14 A preparation method and application of C-labeled 4-dihydroxyborylphenylalanine. Background Art

[0002] As a key project in the clinical pharmacology research of innovative drugs, the study of human material balance provides an important basis for the safety and effectiveness evaluation of innovative drugs. Currently, the most recommended method is to use 14 C-labeled tracer method was used to study the material balance in the human body.

[0003] Boron neutron capture therapy (BNCT) is a new radiotherapy method introduced to the market in recent years. The drug currently on the market overseas is 4-dihydroxyborylphenylalanine (BPA), and there is no drug on the market in China. In order to promote the development of domestic BNCT drugs, it is necessary to study the material balance of the drug BPA in the human body, so it is necessary to study the carbon 14 ( 14 C) Synthesis method of labeled 4-dihydroxyborylphenylalanine (14C-BPA).

[0004] Currently not available 14 C-aniline to 14 There is still a blank in this field regarding the synthesis of C-BPA. Summary of the invention

[0005] The purpose of the present invention is to overcome at least one of the shortcomings of the prior art and provide a 14 C-labeled 4-dihydroxyborylphenylalanine ( 14 C-BPA) preparation method and application.

[0006] The technical solution adopted by the present invention is:

[0007] A sort of 14 C-labeled 4-dihydroxyborylphenylalanine ( 14 The preparation method of C-BPA comprises the following steps:

[0008] S1. 14 C-labeled compound of formula 1 ( 14 C-aniline) is diazotized to generate diazonium salt, and then coupled with acrylonitrile to obtain 14 C-labeled compound of formula 2

[0009] S2. 14 C-labeled compound of formula 2 Hydrolysis of cyano group gives 14C-labeled compound of formula 3

[0010] S3. 14 C-labeled compound of formula 3 Add ammonia to react 14 C-labeled compound of formula 4 The left-handed 14 C-phenylalanine;

[0011] S4.Left-handed 14 Synthesis of C-phenylalanine by iodination reaction 14 C-labeled compound of formula 5 (4-Iodine- 14 C-phenylalanine),

[0012] S5. Protection of 4-iodo- 14 C-amino group of phenylalanine,

[0013] S6. Introducing boronic acid groups through carbon-boron bond coupling reaction,

[0014] S7. Removal of the amino protecting group to obtain

[0015] In some embodiments, the diazotization reaction in step S1 is 14 C-aniline reacts with sodium nitrite (NaNO2) and hydrochloric acid (HCl) to form a diazonium salt, where 14 The molar ratio of C-aniline, sodium nitrite (NaNO2) and hydrochloric acid is 1: (5-50): (10-100); and / or; the temperature of the diazotization reaction is 0°C-5°C, preferably 0°C; and / or; the time of the diazotization reaction is 0.8-1.2h.

[0016] In some embodiments, in step S1, when the diazonium salt and the acrylonitrile are coupled, the amount of acrylonitrile added is 14 The mass of the catalyst is 5-10 times of that of C-aniline, and the coupling reaction time is 1.5-2.5h; the catalyst for the coupling reaction includes at least one of cuprous chloride, cuprous bromide and cuprous iodide, preferably cuprous chloride.

[0017] In some embodiments, in step S2, the hydrolysis reaction is carried out under strong acidic conditions, and the strong acid includes concentrated hydrochloric acid and concentrated sulfuric acid, preferably concentrated hydrochloric acid; the preferred concentrated hydrochloric acid concentration is 8-12 mol / L, and / or; the temperature of the hydrolysis reaction is 70-90°C, and / or; the time of the hydrolysis reaction is 7-9h.

[0018] In some embodiments, in step S3, the mass percentage concentration of ammonia water is 20-30%, the amount of ammonia water added is 10-100 times the mass of compound 3, and / or; the reaction temperature is 90-110°C, and the reaction time is 8-12h.

[0019] In some embodiments, in step S3, the chiral column is not particularly limited and a commercially available product can be used to obtain the left-handed 14 C-phenylalanine.

[0020] In some embodiments, the iodination reaction in step S4 is levorotatory. 14 C-phenylalanine and iodine undergo iodination reaction under the catalysis of an oxidant, wherein 14 The molar ratio of CL-phenylalanine to elemental iodine (I2) is 1:(2-10), the oxidant includes at least one of sodium iodate and sodium periodate, the reaction temperature is 60-80°C, and the reaction time is 9-20h.

[0021] In some preferred embodiments, the iodination reaction is levorotatory 14 C-phenylalanine and iodine undergo iodination reaction under the catalysis of sodium iodate; 14 The molar ratio of CL-phenylalanine, elemental iodine (I2) and sodium iodate (NaIO3) is 1:(2-10):(2-10).

[0022] More preferably, sodium periodate is further added to the above reaction. Sodium periodate (NaIO4) is a strong oxidant / catalyst, which can further oxidize / catalyze the intermediates or unreacted starting materials in the reaction system. The amount of sodium periodate (NaIO4) added is 14 The mass of C-phenylalanine is 0.1-0.5 times.

[0023] In some preferred embodiments, in step S5, the protecting group includes one of tert-butyloxycarbonyl (Boc), benzyloxycarbonyl (Cbz), 9-fluorenylmethyloxycarbonyl (Fmoc), and acetyl (Ac), preferably tert-butyloxycarbonyl (Boc); and / or 4-iodo- 14 The molar ratio of C-phenylalanine to the protecting group is 1:(1.5-5).

[0024] In some preferred embodiments, the protecting group is tert-butyloxycarbonyl (Boc), and step S5 reacts to obtain compound 6

[0025] In some preferred embodiments, the carbon-boron bond coupling reaction in step S6 is a coupling reaction of N-Boc-4-iodo-L-phenylalanine with an isopropyl Grignard reagent and an alkyl borate compound.

[0026] The isopropyl Grignard reagent includes at least one of isopropylmagnesium chloride, isopropyllithium chloride and isopropylmagnesium bromide.

[0027] The borate alkyl ester compound includes one of tributyl borate, trimethyl borate, triethyl borate, triisopropyl borate, tri-n-propyl borate and tri-tert-butyl borate.

[0028] The reaction is carried out in an organic solvent environment, and the organic solvent includes at least one of tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether, ethyl ether, and toluene.

[0029] In some preferred embodiments, compound 6 reacts with isopropyl grignard reagent and tributyl borate to obtain compound 7

[0030] The molar ratio of compound 6 to isopropyl Grignard reagent and tributyl borate is 1:(4.5-8):(2-5), the reaction temperature is -40°C to -60°C, and the reaction time is 8-12h.

[0031] In some embodiments, the reaction scheme of the method is as follows Figure 1 shown.

[0032] The method prepared by any one of the above 14 C-labeled 4-dihydroxyborylphenylalanine ( 14 C-BPA).

[0033] 14 Application of C-labeled 4-dihydroxyborylphenylalanine in pharmacokinetic studies.

[0034] The beneficial effects of the present invention are:

[0035] (1) Commercially available 14 C-aniline is used as the raw material and is efficiently synthesized through 7 steps of reaction. 14 C-BPA.

[0036] (2) The product has high purity, greater than 99%.

[0037] (3) The abundance of carbon isotopes will not be diluted during the reaction, and the product specific activity is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The reaction scheme of the embodiment;

[0039] Figure 2 for 14 H NMR spectrum of C-BPA;

[0040] Figure 3 for 14 Radioactive liquid chromatogram of C-BPA. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0043] The advantages of chemical synthesis are that the specific activity and radiochemical purity of radiolabeled compounds are high, and the labeling position is easy to determine. Therefore, it is currently the most important method for preparing radionuclide labeled compounds. The disadvantages are that the preparation process is complicated, with many steps, a long process, and high cost. There are many differences between radiochemical synthesis and ordinary chemical synthesis: First, in terms of the selection of raw materials, general chemical synthesis can easily select various raw materials and intermediates, while radiolabeled compounds can only select simple radioactive precursors, such as 14 Category C is mainly raw materials obtained directly from the reactor. 14 CO3, etc. 3 H type mainly contains tritium gas ( 3 H2), tritium water ( 3 H2O), sodium borotritide (NaBH3 3 H~NaB 3 H4), lithium aluminum tritide (LiAlH3 3 H~LiAl 3 H4), etc., so the synthesis method is strictly limited by the raw materials; secondly, when designing the synthesis route, it is necessary to consider simplicity and speed; in addition, when preparing high specific activity labeled compounds, violent reactions such as high temperature and high pressure should be avoided as much as possible to reduce the possibility of radioactive contamination.

[0044] As mentioned above, there is no prior art 14 C-aniline to 14 The synthesis report of C-BPA is still blank in this field. The embodiment of the present invention provides a novel method for preparing 14 The C-BPA method is to use commercially available 14 C-aniline is used as the raw material and is efficiently synthesized through 7 steps of reaction. 14C-BPA, the method is relatively mild and easy to promote.

[0045] The method specifically comprises: 14 C-labeled aniline was used as the starting material. First, the diazotization reaction was carried out to 14 C-aniline is docked with acrylonitrile, and then the cyano group is hydrolyzed to obtain the corresponding carboxylic acid. Ammonia is used to convert the chlorine in the molecule into the amino group to obtain 14 C-phenylalanine. 14 C-phenylalanine was separated by chiral column to obtain left-handed 14 C-phenylalanine, followed by L- 14 C-phenylalanine is synthesized via 4-step reaction 14 C-BPA. L-BPA 14 C-phenylalanine is first synthesized by iodination reaction to 4-iodo- 14 C-phenylalanine, then the amino group is protected with tert-butyloxycarbonyl, boric acid is introduced through carbon-boron bond coupling reaction, and finally the tert-butyloxycarbonyl group is removed to obtain 14 C-BPA.

[0046] The reaction process is as follows:

[0047]

[0048] The * in the structure indicates that there is a carbon atom on the benzene ring. 14 C.

[0049] BPA is 4-dihydroxyboryl-phenylalanine, English: 4-Borono-phenylalanine. The left-handed 14 C-BPA.

[0050] Chiral columns, also known as chiral HPLC columns, are chromatographic columns specifically used to separate chiral compounds. The core of chiral columns lies in their chiral stationary phases, which are made of optically active monomers fixed on silica gel or other polymers.

[0051] The technical solution of this application has the following advantages:

[0052] (1) Commercially available 14 C-aniline is used as the raw material and is efficiently synthesized through 7 steps of reaction. 14 C-BPA.

[0053] The commercially available finished product is used as the raw material, which can save the time and energy of synthesizing the initial carbon 14 labeled compound by oneself, and also provide guarantee for the industrial production of the method. The method can efficiently synthesize with only 7 steps of reaction.14 C-BPA can minimize the collection and treatment of radioactive waste, reduce environmental pressure, and reduce waste disposal costs and radiation protection pressure.

[0054] (2) The product has high purity, with radiochemical purity greater than 99%.

[0055] Because of the drug safety issues involved, the purity and toxic impurities of the product are also very strict. The results of nuclear magnetic resonance hydrogen spectrum (NMR hydrogen spectrum) show that the 14 The C-BPA NMR spectrum is clean, and no other impurities are seen. The radioactive liquid chromatography results show 14 The radiochemical purity of C-BPA is greater than 99%.

[0056] (3) The abundance of carbon isotopes will not be diluted during the reaction, and the product has a high specific activity, greater than 50 mCi / mmol, making it suitable as a labeled substrate for pharmacokinetic studies.

[0057] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0058] The raw material 14 C-Aniline is a commercially available product purchased from China Tongfu Group Co., Ltd.

[0059] Example 1

[0060] 1. Synthesis 14 CL-Phenylalanine

[0061]

[0062] (1) At 0°C, 0.48 g 14 C-aniline was slowly added to a hydrochloric acid solution (5 ml, 2.5 mol / L), followed by a 5 mol / L sodium nitrite aqueous solution, and stirred at 0°C for 1 hour;

[0063] (2) Add 0.1 g of cuprous chloride to the reaction solution, then slowly add 0.53 g of acrylonitrile, and stir at room temperature for 2 hours;

[0064] (3) The reaction solution was extracted with ethyl acetate (10 ml), and the extraction was repeated three times in total. The mixture was dried and distilled under reduced pressure to obtain intermediate 2.

[0065] (4) Dissolve the intermediate 2 in 5 ml of concentrated hydrochloric acid, heat to 80° C. and stir for 8 hours, cool the reaction solution to room temperature, and distill the reaction solution under reduced pressure to obtain the intermediate 3;

[0066] (5) Dissolve the intermediate 3 in 5 ml of aqueous ammonia (mass ratio 25%), heat to 100°C, and stir for 10 hours. Cool the reaction solution and remove the solvent by distillation under reduced pressure. The obtained solid is separated using a chiral column to obtain 14 CL-Phenylalanine 320mg.

[0067] 2. Synthesis 14 C-4-iodo-L-phenylalanine

[0068]

[0069] (1) Add 1.6 ml of glacial acetic acid into a 23 ml three-necked flask, cool to 0 °C, and then slowly add 0.3 ml of concentrated sulfuric acid;

[0070] (2) 320 mg of the synthesized 14 CL-phenylalanine was added to the reaction solution, followed by 600 mg of iodine and 400 mg of sodium iodate, and the mixture was heated to 70°C and stirred for 10 hours;

[0071] (3) Add 50 mg of sodium periodate to the reaction solution, continue heating to 70°C and stirring for 10 hours; remove acetic acid by distillation under reduced pressure, and extract the aqueous phase once with ether (5 ml) and once with dichloromethane (5 ml);

[0072] (4) adjusting the pH to 7 using a 5 mol / L potassium hydroxide aqueous solution, and removing the solvent by distillation under reduced pressure to obtain a solid;

[0073] (5) The obtained solid was dissolved in ethanol / water solution (1:1) at 80°C, filtered, and then crystallized at 0°C for 12 hours. 14 C-4-iodo-L-phenylalanine 340mg.

[0074] 3. Synthesis of intermediate 6

[0075]

[0076] (1) 300 mg of 14 C-4-iodo-L-phenylalanine was dissolved in 5 ml of tetrahydrofuran aqueous solution (1:1), 400 mg of potassium carbonate and 500 mg of di-tert-butyl dicarbonate were added in sequence, and stirred at room temperature for 2 hours;

[0077] (2) The pH value of the reaction solution was adjusted to about 2 using a 1 mol / L aqueous hydrochloric acid solution, and tetrahydrofuran in the solution was removed by vacuum distillation. The reaction solution was extracted twice with 20 ml of ethyl acetate, dried over anhydrous magnesium sulfate, filtered, and vacuum distilled to obtain 320 mg of intermediate 6.

[0078] 4. Synthesis 14 C-BPA

[0079]

[0080] (1) 300 mg of intermediate 6 was dissolved in dry tetrahydrofuran (5 mL), replaced with nitrogen, and cooled to -40°C; isopropyl Grignard reagent (1 mol / L, 9 mL) was added, and stirred at -40°C for 2 hours; tributyl borate (693 mg) was slowly added to the reaction solution, and stirred at -40°C for 8 hours;

[0081] (2) Quench the reaction with 1 ml of water, adjust the pH of the reaction solution to about 2, extract the reaction solution twice with 30 ml of ethyl acetate, combine the organic phases, dry with anhydrous sodium sulfate, filter, and distill under reduced pressure to obtain a solid, which is recrystallized with n-heptane to obtain 140 mg of a solid;

[0082] (3) 140 mg of the product obtained in the previous step was dissolved in 5 mL of acetone, cooled to 0° C., 5 mL of 6N hydrochloric acid was added dropwise, and then stirred at 50° C. for 2 hours. A 3 mol / L aqueous sodium hydroxide solution was used to adjust the pH to about 1.5, and stirred for 1 hour. A 3 mol / L aqueous sodium hydroxide solution was then used to adjust the pH to about 7, and stirred overnight. The product was filtered and dried under reduced pressure to obtain a solid. 14 C-BPA 75mg, detection specific activity is 54.5mCi / mmol.

[0083] Example 2

[0084] 1. Synthesis 14 CL-Phenylalanine

[0085]

[0086] (1) At 0°C, 0.96 g 14 C-aniline was slowly added to a hydrochloric acid solution (10 ml, 2.5 mol / L), followed by a 5 mol / L sodium nitrite aqueous solution, and stirred at 0°C for 1 hour;

[0087] (2) 0.15 g of cuprous chloride was added to the reaction solution, followed by slow addition of 1.06 g of acrylonitrile, and the mixture was stirred at room temperature for 2 hours;

[0088] (3) The reaction solution was extracted with ethyl acetate (20 ml), and the extraction was repeated three times in total. The mixture was dried and distilled under reduced pressure to obtain intermediate 2.

[0089] (4) Dissolve the intermediate 2 in 10 ml of concentrated hydrochloric acid, heat to 80° C. and stir for 8 hours, cool the reaction solution to room temperature, and distill the reaction solution under reduced pressure to obtain the intermediate 3;

[0090] (5) Dissolve the intermediate 3 in 10 ml of aqueous ammonia (mass ratio 25%), heat to 100°C, and stir for 10 hours. Cool the reaction solution and remove the solvent by vacuum distillation. The obtained solid is separated using a chiral column to obtain 14 CL-Phenylalanine 640mg.

[0091] 2. Synthesis 14 C-4-iodo-L-phenylalanine

[0092]

[0093] (1) Add 3.2 mL of glacial acetic acid into a 23 mL three-necked flask, cool to 0 °C, and then slowly add 0.6 mL of concentrated sulfuric acid;

[0094] (2) 0.64 g of the synthesized 14 CL-phenylalanine was added to the reaction solution, followed by 1.2 g of iodine and 0.8 g of sodium iodate, and the mixture was heated to 70°C and stirred for 10 hours;

[0095] (3) 100 mg of sodium periodate was added to the reaction solution, and the mixture was heated to 70° C. and stirred for 10 hours. The acetic acid was removed by distillation under reduced pressure, and the aqueous phase was extracted once with ether (10 ml) and once with dichloromethane (10 ml).

[0096] (4) adjusting the pH to 7 using a 5 mol / L potassium hydroxide aqueous solution, and removing the solvent by distillation under reduced pressure to obtain a solid;

[0097] (5) The obtained solid was dissolved in ethanol / water solution (1:1) at 80°C, filtered, and then crystallized at 0°C for 12 hours. 14 C-4-iodo-L-phenylalanine 670mg.

[0098] 3. Synthesis of intermediate 6

[0099]

[0100] (1) 0.6 g of 14 C-4-iodo-L-phenylalanine was dissolved in 10 ml of tetrahydrofuran aqueous solution (1:1), and 0.8 g of potassium carbonate and 1 g of di-tert-butyl dicarbonate were added in sequence, and stirred at room temperature for 2 hours;

[0101] (2) The pH value of the reaction solution was adjusted to about 2 using a 1 mol / L aqueous hydrochloric acid solution, and tetrahydrofuran in the solution was removed by vacuum distillation. The reaction solution was extracted twice with 20 ml of ethyl acetate, dried over anhydrous magnesium sulfate, filtered, and vacuum distilled to obtain 0.64 g of intermediate 6.

[0102] 4. Synthesis 14 C-BPA

[0103]

[0104] (1) 0.6 g of intermediate 6 was dissolved in dry tetrahydrofuran (10 mL), replaced with nitrogen, and cooled to -40°C; isopropyl Grignard reagent (1 mol / L, 18 mL) was added, and stirred at -40°C for 2 hours; tributyl borate (1.4 g) was slowly added to the reaction solution, and stirred at -40°C for 8 hours;

[0105] (2) Quench the reaction with 1 ml of water, adjust the pH of the reaction solution to about 2, extract the reaction solution twice with 30 ml of ethyl acetate, combine the organic phases, dry with anhydrous sodium sulfate, filter, and distill under reduced pressure to obtain a solid, which is recrystallized with n-heptane to obtain 0.3 g of a solid;

[0106] (3) 0.3 g of the product obtained in the previous step was dissolved in 10 mL of acetone, cooled to 0° C., 5 mL of 6N hydrochloric acid was added dropwise, and then stirred at 50° C. for 2 hours. A 3 mol / L aqueous sodium hydroxide solution was used to adjust the pH to about 1.5, and stirred for 1 hour. A 3 mol / L aqueous sodium hydroxide solution was then used to adjust the pH to about 7, and stirred overnight. The product was filtered and dried under reduced pressure to obtain a solid. 14 C-BPA 0.15g, detection specific activity is 54.5mCi / mmol.

[0107] Test example

[0108] 1. The results of Example 1 14 C-BPA was analyzed by nuclear magnetic resonance hydrogen spectrum, and the results are shown in Figure 2 .

[0109] Nuclear magnetic resonance spectroscopy (NMR spectroscopy) is a technique used to analyze the chemical environment of hydrogen atoms in organic compounds. It provides information on the molecular structure by measuring the resonance signal of hydrogen atoms in an external magnetic field.

[0110] Depend on Figure 2 The results show that the NMR spectrum is clean and no other impurities are observed.

[0111] 2. The results of Example 1 14 C-BPA was subjected to radioactive liquid chromatography, and the results are shown in Figure 3 .

[0112] Depend on Figure 3 The results show that the radiochemical purity is greater than 99%.

[0113] 3. Specific activity test

[0114] Specific radioactivity, also known as specific activity, refers to the radioactivity contained in a unit mass of a pure element or compound. The unit is Bq / g. It can also be described by the radioactivity per unit mole of substance. The unit is Bq / mol.

[0115] The specific activity mCi / mmol indicates the radioactivity per unit mole of radioactive nuclides, that is, the number of decays per millimole of radioactive nuclides per unit time. Here, "mCi" is millicurie, which is one thousandth of Curie (Ci), and is the unit of radioactivity; while "mmol" is millimole, which is the unit of the amount of substance. Therefore, the unit mCi / mmol is used to describe the activity per millimole of radioactive substances, and is usually used to characterize the activity intensity of radioactive isotopes.

[0116] Example 1 prepared 14 C-BPA 75 mg, detected specific activity of 54.5 mCi / mmol, prepared in Example 2 14 C-BPA 0.15g, detection specific activity is 54.5mCi / mmol. 14 C-BPA meets the requirements for conducting pharmacokinetic experiments.

[0117] Industrial Applicability

[0118] The present application mainly relates to carbon 14 labeled 4-dihydroxyborylphenylalanine ( 14 The synthesis method of C-BPA) was used to study the pharmacokinetic data of 4-dihydroxyborylphenylalanine.

[0119] This application is about 14 The synthesis method of C-BPA has short steps, high specific activity and mild reaction conditions. The final product has a radiochemical purity of more than 99% and is suitable as a labeled substrate for pharmacokinetic research.

Claims

1. A 14 The method for preparing C-labeled 4-dihydroxyborylphenylalanine is characterized in that: The following steps are involved: S1. 14 C-labeled compound of formula 1 The diazonium salt is generated by diazotization reaction and coupled with acrylonitrile to obtain 14 C-labeled compound of formula 2 S2. 14 C-labeled compound of formula 2 Hydrolysis of cyano group gives 14 C-labeled compound of formula 3 S3. 14 C-labeled compound of formula 3 Add ammonia to react 14 C-labeled compound of formula 4 The left-handed 14 C-phenylalanine; S4.Left-handed 14 Synthesis of C-phenylalanine by iodination reaction 14 C-labeled compound of formula 5 S5. Protection of 4-iodo- 14 C-amino group of phenylalanine, S6. Introducing boronic acid groups through carbon-boron bond coupling reaction, S7. Removal of the amino protecting group to obtain 2. The preparation method according to claim 1, characterized in that: The diazotization reaction in step S1 is: 14 C-aniline reacts with sodium nitrite (NaNO2) and hydrochloric acid (HCl) to form a diazonium salt, where 14 The molar ratio of C-aniline, sodium nitrite and hydrochloric acid is 1:(5-50):(10-100); and / or; the temperature of the diazotization reaction is 0°C-5°C; and / or; the time of the diazotization reaction is 0.8-1.2h.

3. The preparation method according to claim 2, characterized in that: In the step S1, when the diazonium salt and the acrylonitrile are subjected to coupling reaction, the amount of acrylonitrile added is 14 The mass of the C-aniline is 5-10 times; and / or; the coupling reaction time is 1.5-2.5h; and / or; the catalyst for the coupling reaction includes at least one of cuprous chloride, cuprous bromide and cuprous iodide.

4. The preparation method according to claim 1, characterized in that: In the step S2, the hydrolysis reaction is carried out under strong acidic conditions, and the strong acid includes concentrated hydrochloric acid, concentrated sulfuric acid, and / or; the temperature of the hydrolysis reaction is 70-90°C, and the time of the hydrolysis reaction is 7-9h.

5. The preparation method according to claim 1, characterized in that: In the step S3, the mass percentage concentration of ammonia water is 20-30%, and the amount of ammonia water added is 10-100 times the mass of compound 3; and / or; the reaction temperature is 90-110° C., and the reaction time is 8-12 h.

6. The preparation method according to claim 1, characterized in that: The iodination reaction in step S4 is levorotatory. 14 C-phenylalanine and iodine undergo iodination reaction under the catalysis of an oxidant, wherein 14 The molar ratio of CL-phenylalanine to elemental iodine is 1:(2-10), the oxidant comprises at least one of sodium iodate and sodium periodate; and / or; the temperature of the iodination reaction is 60-80° C., and the time of the iodination reaction is 9-20 hours.

7. The preparation method according to claim 1, characterized in that: In the step S5, the protecting group includes one of tert-butyloxycarbonyl (Boc), benzyloxycarbonyl (Cbz), 9-fluorenylmethyloxycarbonyl (Fmoc), and acetyl (Ac), preferably tert-butyloxycarbonyl; and / or; 4-iodo- 14 The molar ratio of C-phenylalanine to the protecting group is 1:(1.5-5).

8. The preparation method according to claim 7, characterized in that: The protecting group is tert-butyloxycarbonyl, and step S5 is reacted to obtain compound 6 9. The method according to any one of claims 1 to 8 prepared 14 C-labeled 4-borylphenylalanine.

10. The method according to claim 9 14 Application of C-labeled 4-dihydroxyborylphenylalanine in pharmacokinetic studies.

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