Carbon-14 labeled tetrahydroprogesterone as well as preparation method and application thereof

Abstract

The invention belongs to the field of radioactive chemical synthesis, and particularly relates to carbon-14 labeled tetrahydroprogesterone as well as a preparation method and application thereof. The carbon-14 labeled tetrahydroprogesterone provided by the invention has a structure as shown in a formula I; the carbon-14 labeled tetrahydroprogesterone provided by the invention has the advantages that the labeled sites are determined, the radiochemical purity and the chemical purity are relatively high, the nuclide carbon-14 is firmly labeled in tetrahydroprogesterone molecules and is not easy to fall off, and the requirements of tracer experiments in pharmacokinetics can be met.

Description

Technical Field

[0001] This invention belongs to the field of radiochemical synthesis, specifically relating to a carbon-14 labeled tetrahydroprogesterone, its preparation method, and its application. Background Technology

[0002] Tetrahydroprogesterone (ALLO), also known as allopregnanolone, is a metabolite of progesterone and a neuroactive steroid, representing a new research direction for the treatment of mood-related disorders. Its molecular formula is C0. 21 H 34 O3. Tetrahydroprogesterone (ALLO) plays an important physiological role in the central nervous system, particularly in regulating mood, anxiety, depression, and cognitive function. ALLO enhances the opening of GABA-mediated chloride channels by binding to γ-aminobutyric acid type A receptors (GABAA receptors), thereby increasing inhibitory transmission in neurons, reducing neuronal excitability, and producing anti-anxiety and antidepressant effects. Furthermore, ALLO also participates in regulating the function of the hypothalamus-pituitary-adrenal axis (HPA axis), influencing stress response and mood regulation. In the international process of new drug development, pharmacokinetic studies of new drugs largely rely on radioisotope tracing techniques. my country's "Technical Guidelines for Non-Clinical Pharmacokinetic Studies of Drugs" also explicitly recommends the use of radioisotope labeling, and carbon-14 labeled tetrahydroprogesterone is an essential tracer for conducting such studies.

[0003] To date, there are few reports on the isotopic labeling of tetrahydroprogesterone, and most of them are labeled with the stable isotope deuterium; reports on carbon-14 labeled tetrahydroprogesterone are extremely rare. Furthermore, even looking at the entire spectrum of steroidal substances, reports on radioactive carbon-14 isotopic labeling are uncommon. This is mainly due to the complex structure of steroidal compounds, which makes efficient carbon-14 labeling synthesis difficult. Eduardo G. Gros et al. previously reported a method for synthesizing the C-14 carbon of the 17-acetyl carbon of the D ring of steroidal compounds derived from chenodeoxycholic acid using C-14 dimethylcadmium. This method uses the corresponding acyl chloride compound as a raw material and radioactive C-14 dimethylcadmium as a radioactive source to synthesize a radioactive compound labeled with acetyl α-methyl C-14. However, this method has many technical and safety issues: First, dimethylcadmium itself is a highly toxic substance, and C-14 labeled dimethylcadmium is even more expensive and rare, making it difficult to procure; second, the reaction yield is low, only 36%, resulting in a large waste of raw materials and generating a large amount of radioactive waste, further increasing costs. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon-14 labeled tetrahydroprogesterone, its preparation method and application. The carbon-14 labeled tetrahydroprogesterone provided by this invention has a defined labeling site, and the carbon-14 nuclide is firmly labeled in the tetrahydroprogesterone molecule and is not easy to fall off, which can meet the requirements of tracer experiments in pharmacokinetics.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a carbon-14 labeled tetrahydroprogesterone having the structure shown in Formula I:

[0007]

[0008] This invention provides a method for preparing carbon-14 labeled tetrahydroprogesterone as described above, comprising the following steps:

[0009] (1) Under negative pressure, barium carbonate of carbon-14 and inorganic acid are mixed to carry out the first metathesis reaction to obtain carbon-14 carbon dioxide; carbon-14 carbon dioxide and lithium triethylborohydride are reduced to obtain lithium [carbonyl-14C] formate.

[0010] (2) Under negative pressure, lithium C-14 formate and inorganic acid are mixed to carry out a second metathesis reaction to obtain carbon C-14 monoxide; the carbon C-14 monoxide, trifluoromethanesulfonate enol ester with the structure of formula 2, palladium-based catalyst and weak base are dissolved and carbonylation reaction is carried out to obtain compound 3 with the structure of formula 3.

[0011]

[0012] (3) Compound 3 was subjected to hydrogen reduction reaction under hydrogen and palladium on carbon catalyst to obtain compound 4 with the structure of formula 4.

[0013]

[0014] (4) Under a protective atmosphere, compound 4, condensing agent, organic base and dimethyl hydroxylamine hydrochloride are mixed and condensed to obtain compound 5 with the structure of formula 5;

[0015]

[0016] (5) Under a protective atmosphere, compound 5 and methyllithium were subjected to a methylation reaction to obtain compound 6 having the structure of formula 5;

[0017]

[0018] (6) Under a protective atmosphere, compound 6 was subjected to a deprotection reaction to obtain the carbon-14 labeled tetrahydroprogesterone.

[0019] Preferably, the preparation of the trifluoromethanesulfonate enol ester includes the following steps:

[0020] After dissolving androstenone, imidazole, and TBSCl, a substitution reaction was carried out to obtain compound 1 with the structure shown in Formula 1.

[0021] After dissolving the compound 1, LiHMDS and PhNTf2, the trifluoromethanesulfonate enol ester was obtained by enolization / trifluoromethanesulfonation reaction.

[0022] Preferably, the carbonyl insertion reaction is carried out at a temperature of 25–100°C for 3–10 hours.

[0023] Preferably, the hydrogen reduction reaction is carried out at a temperature of 25–50°C for a time of 12–72 hours.

[0024] Preferably, the condensing agent includes one or more of EDCI, HOBT, and HATU; the organic base includes one or more of DIPEA, triethylamine, and DBU.

[0025] Preferably, the condensation reaction is carried out at a temperature of 25–50°C for 2–24 hours.

[0026] Preferably, the methylation reaction is carried out at a temperature of 0–30°C for 1–8 hours.

[0027] Preferably, the deprotection reaction is carried out at a temperature of 0–40°C for 5–20 hours.

[0028] The present invention also provides the application of carbon-14 labeled tetrahydroprogesterone as described in the above technical solution or carbon-14 labeled tetrahydroprogesterone prepared by the preparation method described in the above technical solution as a tracer in pharmacokinetics.

[0029] This invention provides a carbon-14 labeled tetrahydroprogesterone having the structure shown in Formula I:

[0030] The carbon-14 labeling site for tetrahydroprogesterone provided by this invention is determined, and the radiochemical purity and chemical purity are both high. The carbon-14 nuclide is firmly labeled in the tetrahydroprogesterone molecule and is not easy to fall off, which can meet the requirements of tracer experiments in pharmacokinetics. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The radiochromatogram of carbon-14 labeled tetrahydroprogesterone prepared in Example 1 of this invention;

[0033] Figure 2 This is a high-performance liquid chromatogram of carbon-14 labeled tetrahydroprogesterone prepared in Example 1 of the present invention. Detailed Implementation

[0034] This invention provides a carbon-14 labeled tetrahydroprogesterone having the structure shown in Formula I:

[0035]

[0036] The present invention also provides a method for preparing carbon-14 labeled tetrahydroprogesterone as described in the above technical solution, comprising the following steps:

[0037] (1) Under negative pressure, barium carbonate of carbon-14 and inorganic acid are mixed to carry out the first metathesis reaction to obtain carbon-14 carbon dioxide; carbon-14 carbon dioxide and lithium triethylborohydride are reduced to obtain lithium [carbonyl-14C] formate.

[0038] (2) Under negative pressure, lithium C-14 formate and inorganic acid are mixed to carry out a second metathesis reaction to obtain carbon C-14 monoxide; the carbon C-14 monoxide, trifluoromethanesulfonate enol ester with the structure of formula 2, palladium-based catalyst and weak base are dissolved and carbonylation reaction is carried out to obtain compound 3 with the structure of formula 3.

[0039]

[0040] (3) Compound 3 was subjected to hydrogen reduction reaction under hydrogen and palladium on carbon catalyst to obtain compound 4 with the structure of formula 4.

[0041]

[0042] (4) Under a protective atmosphere, compound 4, condensing agent, organic base and dimethyl hydroxylamine hydrochloride are mixed and condensed to obtain compound 5 with the structure of formula 5;

[0043]

[0044] (5) Under a protective atmosphere, compound 5 and methyllithium were subjected to a methylation reaction to obtain compound 6 having the structure of formula 5;

[0045]

[0046] (6) Under a protective atmosphere, compound 6 was subjected to a deprotection reaction to obtain the carbon-14 labeled tetrahydroprogesterone.

[0047] In this invention, under negative pressure, barium carbonate (C-14) and an inorganic acid are mixed to undergo a first metathesis reaction to obtain carbon-14 carbon dioxide; carbon-14 carbon dioxide is then reduced with lithium triethylborohydride to obtain lithium [carbonyl-14C]formate.

[0048] In one embodiment of the present invention, the inorganic acid preferably includes one or more of phosphoric acid, sulfuric acid, and hydrochloric acid; the sulfuric acid is preferably concentrated sulfuric acid; the mass concentration of the phosphoric acid is preferably 50-85%, specifically 50%, 60%, 70%, or 85%; the mass concentration of the hydrochloric acid is preferably 10-37%, specifically 10%, 20%, 25%, or 37%. In another embodiment of the present invention, the mass-to-volume ratio of the barium carbonate (C-14) to the inorganic acid is preferably 200 mg: 4-8 mL, specifically 200 mg: 6 mL.

[0049] In one embodiment of the present invention, the molar ratio of carbon-14 carbon dioxide and lithium triethylborohydride is preferably 1 mmol: 1 to 1.5 mmol, specifically 1: 1.3 mmol. In another embodiment of the present invention, the temperature of the reduction reaction is preferably -50 to 50°C, specifically 0°C; the time is preferably 0.5 to 5 hours, specifically 1 hour, 2 hours, or 4 hours. In another embodiment of the present invention, the reduction reaction is preferably carried out under a nitrogen atmosphere. In another embodiment of the present invention, after reduction, the reaction is preferably quenched with methanol, and the reduction reaction solution is concentrated to dryness to obtain lithium [carbonyl-14C]formate.

[0050] In this invention, under negative pressure, lithium C-14 formate and an inorganic acid are mixed to undergo a second metathesis reaction to obtain carbon C-14 monoxide; the carbon C-14 monoxide is dissolved with enol trifluoromethanesulfonate (compound 2) having the structure shown in Formula 2, a palladium-based catalyst and a weak base to undergo a carbonylation reaction to obtain compound 3 having the structure shown in Formula 3.

[0051] In one embodiment of the present invention, during the second metathesis reaction, the inorganic acid preferably includes one or more of phosphoric acid, sulfuric acid, and hydrochloric acid; the sulfuric acid is preferably concentrated sulfuric acid; the mass concentration of the phosphoric acid is preferably 50-85%, specifically 50%, 60%, 70%, or 85%; the mass concentration of the hydrochloric acid is preferably 10-37%, specifically 10%, 20%, 25%, or 37%. In another embodiment of the present invention, the molar ratio of lithium C-14 formate to the volume ratio of the inorganic acid is preferably 3 mmol:4-8 mL, specifically 3 mmol:6 mL.

[0052] In one embodiment of the present invention, the preparation of the trifluoromethanesulfonate enol ester includes the following steps:

[0053] After dissolving androstenone, imidazole, and TBSCl, a substitution reaction was carried out to obtain compound 1 with the structure shown in Formula 1.

[0054] The compound 1, LiHMDS and PhNTf2 were mixed and then subjected to an enolization / trifluoromethanesulfonation reaction to obtain the trifluoromethanesulfonate enol ester.

[0055] In one embodiment of the present invention, the mass ratio of androsterone to TBSCl is preferably 2900:1510-4530, specifically 2900:3624; in another embodiment of the present invention, the mass ratio of androsterone to imidazole is preferably 2900:1360-3400, specifically 2900:2720. In another embodiment of the present invention, the temperature of the substitution reaction is preferably 0-50°C, specifically 25°C, and the time is preferably 1-5 hours, specifically 2 hours. In another embodiment of the present invention, after the substitution reaction, the substitution reaction solution is further extracted by DCM, and the resulting organic phase is dried and purified by column chromatography; the eluent for the column chromatography purification is preferably petroleum ether and ethyl acetate in a volume ratio of 100:1.

[0056] In one embodiment of the present invention, compound 1 is preferably used in the form of a solution of compound 1, wherein the solvent in the solution of compound 1 is preferably THF; LiHMDS and PhNTf2 are preferably used in the form of a solution of LiHMDS and PhNTf2, wherein the solvent in the solution of LiHMDS and PhNTf2 is preferably THF. In one embodiment of the present invention, the mass ratio of compound 1 to PhNTf2 is preferably 2126:1900 to 3800, specifically preferably 2126:1900, 2126:2500, or 2126:3800. In one embodiment of the present invention, the mixing of compound 1, LiHMDS, and PhNTf2 is preferably achieved by mixing compound 1 and THF in a dry ice-ethanol bath, followed by dropwise addition of the THF solution of LiHMDS and PhNTf2.

[0057] In one embodiment of the present invention, the enolization / trifluoromethanesulfonation reaction is preferably carried out by naturally heating to room temperature in a dry ice-ethanol bath; the reaction time is preferably 1 to 5 hours, specifically 2 hours. In another embodiment of the present invention, after the enolization / trifluoromethanesulfonation reaction, the reaction solution is further further purified by adding an appropriate amount of saturated ammonium chloride and extracting with ethyl acetate. The resulting ethyl acetate phase is washed with saturated sodium chloride, dried over anhydrous sodium sulfate, and then purified by column chromatography; the eluent for column chromatography purification is preferably petroleum ether.

[0058] In one embodiment of the present invention, the palladium-based catalyst preferably comprises one or more of bis(triphenylphosphine)palladium acetate, palladium acetate, tetra(triphenylphosphine)palladium, and dppf palladium dichloride. In another embodiment of the present invention, the weak base preferably comprises one or more of potassium acetate, potassium carbonate, and sodium carbonate.

[0059] In one embodiment of the present invention, the carbon-14 monoxide, the trifluoromethanesulfonate enol ester (compound 2) having the structure shown in Formula 2, the palladium-based catalyst, and the solvent for weak base dissolution are preferably one or more of N,N,-dimethylformamide, tetrahydrofuran, dioxane, and acetonitrile. In one embodiment of the present invention, the molar ratio of compound 2 to carbon-14 monoxide is preferably 1.0–4.0:1.0, specifically 1.1:1.0. In one embodiment of the present invention, the temperature of the carbonylation reaction is preferably 25–100°C, specifically 25°C, 30°C, 40°C, 50°C, 70°C, 80°C, or 100°C, and the time is preferably 3–10 hours, specifically 5 hours. In one embodiment of the present invention, after the carbonylation reaction, the reaction solution is adjusted to acidity and extracted with DCM. The resulting organic phase is washed with water, dried, and then purified by column chromatography (eluent is petroleum ether and ethyl acetate in a 1:1 volume ratio) to obtain compound 3.

[0060] (3) Compound 3 was subjected to hydrogen reduction reaction under hydrogen and palladium on carbon catalyst to obtain compound 4 with the structure of formula 4.

[0061] In one embodiment of the present invention, compound 3 is preferably used in the form of a solution of compound 3; the solvent in the solution of compound 3 is preferably one or more of methanol, ethanol, ethyl acetate, and tetrahydrofuran. In one embodiment of the present invention, the temperature of the hydrogen reduction reaction is preferably 25–50°C, specifically 25°C, 30°C, 40°C, or 50°C; the time is preferably 12–72 hours, specifically 12 hours, 24 hours, 36 hours, 48 ​​hours, or 72 hours. In one embodiment of the present invention, after the hydrogen reduction reaction, the hydrogen reduction reaction solution is filtered, the filter cake is washed with THF and MeOH, the organic phase is collected, and evaporated to dryness to obtain compound 4.

[0062] (4) Under a protective atmosphere, compound 4, condensing agent, organic base and dimethyl hydroxylamine hydrochloride are mixed and condensed to obtain compound 5 with the structure of formula 5.

[0063] In one embodiment of the present invention, compound 4 is preferably used in the form of a solution of compound 4; the solvent in the solution of compound 4 is preferably one or more of dichloromethane, tetrahydrofuran, and acetonitrile. In one embodiment of the present invention, the condensing agent preferably includes one or more of EDCI, HOBT, and HATU, specifically EDCI. In one embodiment of the present invention, the organic base preferably includes one or more of DIPEA, triethylamine, and DBU, specifically DIPEA. In one embodiment of the present invention, the protective atmosphere is preferably nitrogen. In one embodiment of the present invention, the mass ratio of compound 4 to dimethyl hydroxylamine hydrochloride is preferably 1223:400-500, specifically 1223:411.6.

[0064] In one embodiment of the present invention, the temperature of the condensation reaction is preferably 25–50°C, specifically 25°C, 30°C, 40°C, or 50°C; the time is preferably 2–24 hours, specifically 2 hours, 10 hours, 12 hours, 15 hours, or 24 hours. In another embodiment of the present invention, after the condensation reaction, the condensation reaction solution is extracted and concentrated, and then the concentrate is purified by column chromatography to obtain compound 5. In another embodiment of the present invention, the eluent for the column chromatography purification is preferably petroleum ether and ethyl acetate; the volume ratio of petroleum ether to ethyl acetate is preferably 25:1.

[0065] (5) Under a protective atmosphere, compound 5 and methyllithium were subjected to a methylation reaction to obtain compound 6 having the structure of formula 6.

[0066] In one embodiment of the present invention, compound 5 is preferably used in the form of a solution of compound 5; the solvent in the solution of compound 5 is preferably one or more of tetrahydrofuran, diethyl ether, and dioxane; the protective atmosphere is preferably nitrogen. In one embodiment of the present invention, the mass ratio of compound 5 to lithium methyl is preferably 778:15-31, specifically 778:22.

[0067] In one embodiment of the present invention, the temperature of the methylation reaction is preferably 0–30°C, specifically 25°C, and the time is 1–8 hours, specifically 4 hours. In another embodiment of the present invention, after the methylation reaction, the methylation reaction solution is further purified by column chromatography to obtain compound 6. In another embodiment of the present invention, the eluent for the column chromatography purification is preferably petroleum ether and ethyl acetate; the volume ratio of petroleum ether to ethyl acetate is preferably 150:1.

[0068] (6) Under a protective atmosphere, compound 6 was subjected to a deprotection reaction to obtain the carbon-14 labeled tetrahydroprogesterone.

[0069] In one embodiment of the present invention, compound 6 is preferably used in the form of a solution of compound 6; the solvent in the solution of compound 6 is preferably one or more of tetrahydrofuran, acetonitrile, and ethanol. In one embodiment of the present invention, the reagent for the deprotection reaction is preferably hydrochloric acid; the concentration of the hydrochloric acid is preferably 2-12M, specifically 6M. In one embodiment of the present invention, the protective atmosphere is preferably nitrogen. In one embodiment of the present invention, the mass ratio of compound 6 to the volume ratio of hydrochloric acid is preferably 604 mg: 1.5-3.0 mL, specifically 604 mg: 2.3 mL.

[0070] In one embodiment of the present invention, the temperature of the deprotection reaction is preferably 0–40°C, specifically 25°C, 30°C, or 40°C; the time is preferably 5–20 hours, specifically 5 hours, 10 hours, 15 hours, or 20 hours. In another embodiment of the present invention, after the deprotection reaction, the deprotection reaction solution is further extracted with methyl ether and then purified by column chromatography; the eluent for the column chromatography purification is preferably petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is preferably 150:1.

[0071] The preparation method provided by this invention not only achieves the labeled synthesis of tetrahydroprogesterone, but also provides valuable reference for the labeled synthesis of other related steroidal compounds. Compared with the previously reported carbon-14 dimethyl cadmium reagent, the above method has significant improvements and enhancements in terms of safety, economy, and environmental friendliness.

[0072] The present invention also provides the application of carbon-14 labeled tetrahydroprogesterone as described in the above technical solution or carbon-14 labeled tetrahydroprogesterone prepared by the preparation method described in the above technical solution as a tracer in pharmacokinetic studies.

[0073] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0074] Example 1

[0075] 1) In a 100 mL round-bottom flask, add 2900 mg of androstenedione, 2720 mg of imidazole, and 50 mL of DCM sequentially. While stirring at 25 °C, add dropwise a 25 mL solution of TBSCl (3624 mg) in DCM. After the addition is complete, stir at 25 °C for 2 h. After the reaction is complete, add an appropriate amount of water, separate the layers, and collect the DCM phase. Extract the aqueous phase four times with DCM, combine the organic phases, dry them over anhydrous sodium sulfate, and then purify them by column chromatography. The eluent for column chromatography purification is petroleum ether and ethyl acetate in a volume ratio of 100:1, yielding compound 1 (white solid, 2986 mg, 7.4 mmol, yield: 74%).

[0076] The reaction equation that occurs in 1) is as follows:

[0077]

[0078] 2) In a 100 mL round-bottom flask, compound 1 (2126 mg) and THF (53 mL) were added sequentially. The mixture was stirred in a dry ice-ethanol bath, and then a solution of 5.25 mmol LiHMDS and PhNTf2 (1900 mg) in THF (5.25 mL) was added dropwise. After the addition was complete, the mixture was allowed to cool to room temperature and stirred for 2 hours. After the reaction was complete, 50 mL of saturated ammonium chloride was added, followed by extraction with ethyl acetate. The resulting ethyl acetate phase was washed with saturated sodium chloride, dried over anhydrous sodium sulfate, and then purified by column chromatography. The eluent for column chromatography was petroleum ether, which yielded compound 2 (colorless oily liquid, 2563 mg, 4.86 mmol, yield: 92%).

[0079] The reaction equation that occurs in step 2) is as follows:

[0080]

[0081] 3) Set up a gas circulation device and add 200mg to a 25mL three-necked flask A. 14 C-Ba₂CO₃ was dehydrated at 250℃, and the airtightness was checked for 4 hours. 1.1 mmol of Et₃BHLi was added to a 25 mL three-necked flask B and stirred in an ice bath. 6 mL of concentrated sulfuric acid was added dropwise to three-necked flask A, and the generated carbon dioxide (1 mmol) was passed into three-necked flask B to carry out the reduction reaction (reaction temperature 0℃, time 2 hours). After the reaction was complete, 4 mL of methanol was added to three-necked flask B, and the reaction was quenched by stirring for 5 minutes. The solvent in three-necked flask B was dried with a 70℃ hot air gun, then drained dry with a 70℃ oil pump, and directly added to the next step.

[0082] The reaction equation that occurs in step 3) is as follows:

[0083]

[0084] 4) Set up a gas circulation device; the 25mL three-necked flask A contains 3mmol. 14In a 50 mL three-necked flask B containing C-HCOOLi, 22 mg of KOAc was added, and the mixture was dehydrated at 250 °C. The airtightness was checked for 4 hours. Then, 3.3 mmol of compound 2 and 315 mg of Pd(OAc)2(PPh3)2 were dissolved in 33 mL of LDM and injected into the three-necked flask B, and a vacuum was applied. 6 mL of concentrated sulfuric acid was injected into the three-necked flask A, and the resulting carbon monoxide (1 mmol) was introduced into the three-necked flask B. The reaction was carried out at 25 °C for 5 hours. After the reaction was complete, 10 mL of water was added to the three-necked flask B, and the solution was adjusted to acidity with 0.5 M HCl. Extraction was performed using DCM, and the organic phase was washed three times with water and dried with anhydrous sodium sulfate. The dried organic phase was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 1:1) to give compound 3 (1305 mg, 3.0 mmol).

[0085] The reaction equation that occurs in 4) is as follows:

[0086]

[0087] 5) Add 315 mg of compound 3, 913 mg of Pd / C, and 10 mL of MeOH to a 100 mL round-bottom flask. After replacing the air with hydrogen, continue purging with hydrogen gas and stir at 25 °C for 72 hours to carry out the hydrogen reduction reaction. After the reaction is complete, filter the reaction solution, wash the filter cake with THF and MeOH, collect the organic phase, and evaporate to dryness to obtain compound 4 (white solid, 1223 mg).

[0088] The reaction equation that occurs in 5) is as follows:

[0089]

[0090] 6) Add 1223 mg of compound 4 to a 50 mL round-bottom flask, then add 411.6 mg of HNCH3(OCH3) sequentially. . HCl, 502 mg DMAP, 806 mg EDCI, and 19 mL LDCM were added and stirred overnight (15 h) at 25 °C. After the reaction was complete, 30 mL of saturated sodium chloride was added, and the dichloromethane phase was collected. The aqueous phase was extracted three times with ethyl acetate. The dichloromethane and ethyl acetate phases were combined and concentrated. The concentrate was purified by column chromatography using petroleum ether and ethyl acetate as eluents in a volume ratio of 25:1 to give compound 5 (white solid, 778 mg, 1.62 mmol).

[0091] The reaction equation that occurs in 6) is as follows:

[0092]

[0093] 7) Add 778 mg of compound 5 to a 50 mL round-bottom flask, add 16 mL of THF, purge with nitrogen, and stir in an ice bath for 15 min. Slowly add 22 mg of MeLi dropwise. After the addition is complete, allow the temperature to rise naturally to 25 °C and stir for 4 h. After the reaction is complete, add 30 mL of saturated ammonium chloride and stir for 3 min to quench the reaction. Collect the upper organic phase, extract the aqueous phase three times with 10 mL of ethyl acetate, combine the organic phases, concentrate, and then purify by column chromatography using petroleum ether and ethyl acetate as eluents in a volume ratio of 150:1 to obtain target compound 6 (white solid, 604 mg, 1.4 mmol).

[0094] The reaction equation that occurs in 7) is as follows:

[0095]

[0096] 8) Add 604 mg of compound 6 to a 50 mL round-bottom flask, add 14 mL of THF, and stir at room temperature. Add 2.3 mL of 6 MHCl dropwise. After the addition is complete, place the flask in an oil bath at 25 °C and stir for 10 hours. After the reaction is complete, add water, extract four times with methyl ether, and evaporate to dryness to obtain 456 mg of white solid. Then, purify the solid by column chromatography (eluent: petroleum ether and ethyl acetate, with a volume ratio of 150:1) to obtain the target compound (white solid, 357 mg, 1.1 mmol).

[0097] The reaction equation that occurs in 8) is as follows:

[0098]

[0099] Figure 1 The radiochromatogram of carbon-14 labeled tetrahydroprogesterone prepared in Example 1 is shown below. Figure 1 It can be concluded that the radioactivity purity is 100%, which means that there are almost no other radioactive impurities, thus meeting the requirements for pharmacokinetic studies.

[0100] Figure 2 This is a high-performance liquid chromatogram of carbon-14 labeled tetrahydroprogesterone prepared in Example 1 of this invention. Figure 2 It can be seen that the chemical purity is 98.75% and the maximum single impurity content is 0.9%, which meets the requirements for pharmacokinetic studies.

[0101] In Example 1, the specific activity measured by a liquid scintillation analyzer was 54.04 mCi / mmol; the chemical purity measured by high performance liquid chromatography was 98.75%; and the radiochemical purity measured by a flowing liquid scintillation analyzer was 100%.

[0102] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A carbon-14 labeled tetrahydroprogesterone, characterized in that, It has the structure shown in Equation I:

2. The method for preparing carbon-14 labeled tetrahydroprogesterone according to claim 1, characterized in that, Includes the following steps: (1) Under negative pressure, barium carbonate of carbon-14 and inorganic acid are mixed to carry out the first metathesis reaction to obtain carbon-14 carbon dioxide; carbon-14 carbon dioxide and lithium triethylborohydride are reduced to obtain lithium [carbonyl-14C] formate. (2) Under negative pressure, lithium C-14 formate and inorganic acid are mixed to carry out a second metathesis reaction to obtain carbon C-14 monoxide; the carbon C-14 monoxide, trifluoromethanesulfonate enol ester with the structure of formula 2, palladium-based catalyst and weak base are dissolved and carbonylation reaction is carried out to obtain compound 3 with the structure of formula 3. (3) Compound 3 was subjected to hydrogen reduction reaction under hydrogen and palladium on carbon catalyst to obtain compound 4 with the structure of formula 4. (4) Under a protective atmosphere, compound 4, condensing agent, organic base and dimethyl hydroxylamine hydrochloride are mixed and condensed to obtain compound 5 with the structure of formula 5; (5) Under a protective atmosphere, compound 5 and methyllithium were subjected to a methylation reaction to obtain compound 6 having the structure of formula 5; (6) Under a protective atmosphere, compound 6 was subjected to a deprotection reaction to obtain the carbon-14 labeled tetrahydroprogesterone.

3. The preparation method according to claim 2, characterized in that, The preparation of the trifluoromethanesulfonate enol ester includes the following steps: After dissolving androstenone, imidazole, and TBSCl, a substitution reaction was carried out to obtain compound 1 with the structure shown in Formula 1. After dissolving the compound 1, LiHMDS and PhNTf2, the trifluoromethanesulfonate enol ester was obtained by enolization / trifluoromethanesulfonation reaction.

4. The preparation method according to claim 2, characterized in that, The carbonyl insertion reaction is carried out at a temperature of 25–100°C for 3–10 hours.

5. The preparation method according to claim 2, characterized in that, The hydrogen reduction reaction is carried out at a temperature of 25–50°C for a duration of 12–72 hours.

6. The preparation method according to claim 2, characterized in that, The condensing agent includes one or more of EDCI, HOBT, and HATU; the organic base includes one or more of DIPEA, triethylamine, and DBU.

7. The preparation method according to claim 2, characterized in that, The condensation reaction is carried out at a temperature of 25–50°C for 2–24 hours.

8. The preparation method according to claim 2, characterized in that, The methylation reaction is carried out at a temperature of 0–30°C for 1–8 hours.

9. The preparation method according to claim 2, characterized in that, The deprotection reaction is carried out at a temperature of 0–40°C for 5–20 hours.

10. The use of the carbon-14 labeled tetrahydroprogesterone of claim 1 or the carbon-14 labeled tetrahydroprogesterone prepared by any one of claims 2 to 9 as a tracer in pharmacokinetics.

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