A method for synthesizing a stable isotope-labeled metronidazole
By employing multiple hydrogen-deuterium exchange methods and optimizing reaction conditions, the problems of low yield and abundance in the synthesis of stable isotope-labeled metronidazole were solved, achieving the synthesis of high-purity and high-abundance metronidazole, which is suitable for pharmaceutical and biochemical research.
Patent Information
- Application Number
- CN202411123903.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-16
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2044-08-16
AI Technical Summary
In existing technologies, the synthesis yield and abundance of stable isotope-labeled metronidazole are low, and it is not suitable for large-scale production, which cannot meet the needs of domestic food safety supervision and testing.
A multi-hydrogen-deuterium exchange method was adopted. By controlling the molar ratio of temperature, catalyst and deuterium source, a deuteration reaction was carried out in deuterated water using an alkaline catalyst. The pH value was adjusted by combining deuterated acid, and finally purified by recrystallization of ethanol. The reaction conditions were optimized to improve purity and abundance.
A high-yield and high-abundance stable isotope-labeled metronidazole synthesis was achieved, with improved product purity and stability, making it suitable for drug research, biochemical research, and medical diagnostics.
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Figure CN118652216B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of organic synthesis, and particularly relates to a synthesis method of stable isotope-labeled metronidazole. BACKGROUND
[0002] Metronidazole (C6H9N3O3) is a synthetic antibiotic derived from azomycin, which was first discovered in Streptomyces culture in the 1950s. Metronidazole has strong anti-anaerobic bacteria effect and is widely used in the prevention and treatment of coccidiosis, histomoniasis and hexamitiasis in poultry breeding. Studies have shown that metronidazole and its metabolites have carcinogenic / mutagenic effects.
[0003] Currently, in the national standard GB 31658.23-2022 "Determination of nitroimidazole drug residues in animal food", metronidazole-D3 is used as an internal standard. Stable isotope dilution mass spectrometry is internationally recognized as the "gold standard" for trace detection, which can significantly reduce the matrix effect and improve the accuracy of the detection results. Using the stable isotope-labeled compound corresponding to the compound as an internal standard for detection and quantification by internal standard method can significantly improve the accuracy of the detection results and reduce the detection limit of the compound.
[0004] At present, there is no corresponding stable isotope-labeled internal standard compound in China, and the imported products from abroad are expensive, have long supply cycle and unstable supply. Therefore, the development of stable isotope-labeled metronidazole internal standard reagent is of great significance to the related fields of food safety supervision and detection in China.
[0005] In the development of stable isotope-labeled metronidazole internal standard reagent, one existing method is to convert CH3 of metronidazole to CD3 by hydrogen-deuterium exchange to obtain deuterated metronidazole. The process is as follows: under nitrogen environment, metronidazole (34.2 mg, 0.2 mmol), benzoic acid (49 mg, 0.04 mmol) and 1 mL of D2O are refluxed at 120℃ for 48 hours. Thin layer chromatography is used to monitor the reaction process. After completion, the mixture is neutralized with saturated NaHCO3 aqueous solution, and extracted with ethyl acetate (3 mL) three times. The separated organic layer is combined and dried with anhydrous sodium sulfate. Then the product is obtained by distillation under reduced pressure. The synthesis route is as follows:
[0006] .
[0007] This process is from India and uses acidic conditions. Although deuterated metronidazole is successfully prepared, it cannot be scaled up, the exchange rate is particularly low, the yield is also very low, and the abundance is difficult to improve, which is not suitable for practical application. SUMMARY
[0008] The technical problems to be solved by the present application are: overcoming the shortcomings of the prior art, providing a synthesis method of stable isotope labeled metronidazole with high yield and high abundance.
[0009] The technical solution adopted by the present application to solve its technical problems is: a synthesis method of stable isotope labeled metronidazole, characterized by the following preparation steps:
[0010] 1) One hydrogen-deuterium exchange: adding metronidazole (metronidazole without deuterium substitution), deuterium source, and catalyst solution to the reaction container, the catalyst solution being prepared by dissolving alkaline catalyst in deuterium water, the molar ratio of metronidazole, deuterium source, alkaline catalyst, and deuterium water being 1:8~13:0.35~0.65:8~13; after reaction at 75℃~85℃ for 110min~130min, the temperature is lowered to room temperature, and the mixture is left to stand for 10h~15h; adjusting the pH to 6~7 using deuterium acid, and removing the solvent to obtain the one hydrogen-deuterium exchange product (metronidazole subjected to one hydrogen-deuterium exchange);
[0011] 2) Second hydrogen-deuterium exchange: adding the one hydrogen-deuterium exchange product obtained in step 1) and deuterium source to the reaction container, and adding catalyst solution under stirring, the catalyst solution being prepared by dissolving alkaline catalyst in deuterium water, the molar ratio of the one hydrogen-deuterium exchange product, deuterium source, alkaline catalyst, and deuterium water being 1:14~17:0.35~0.65:14~17; again reacting at 75℃~85℃ for 110min~130min, and then lowering the temperature to room temperature, and leaving the mixture to stand for 10h~15h; adjusting the pH to 6~7 using deuterium acid, and removing the solvent to obtain the second hydrogen-deuterium exchange product (metronidazole subjected to second hydrogen-deuterium exchange);
[0012] 3) Third hydrogen-deuterium exchange: adding the second hydrogen-deuterium exchange product obtained in step 2) and deuterium source to the reaction container, and adding catalyst solution under stirring, the catalyst solution being prepared by dissolving alkaline catalyst in deuterium water, the molar ratio of the second hydrogen-deuterium exchange product, deuterium source, alkaline catalyst, and deuterium water being 1:7~12:0.35~0.65:7~12; again reacting at 75℃~85℃ for 110min~130min, and then lowering the temperature to room temperature, and leaving the mixture to stand for 10h~15h; adjusting the pH to 6~7 using deuterium acid, and removing the solvent to obtain crude deuterium-substituted metronidazole;
[0013] 4) Recrystallizing the crude deuterium-substituted metronidazole with ethanol to obtain deuterium-substituted metronidazole.
[0014] The present application effectively improves the purity and abundance of isotopically labeled metronidazole through multiple hydrogen-deuterium exchanges, ensures the quality and stability of the obtained product, and realizes high raw material utilization rate, and the obtained product has high purity and high abundance. The cost of deuterium-substituted raw materials is relatively high, in order to save costs as much as possible, the present application performs multiple parallel feeding, and has the optimal molar ratio.
[0015] In the second and third hydrogen-deuterium exchange steps, the mother liquor obtained after removing the solvent can be recycled for exchange pretreatment of metronidazole in the first hydrogen-deuterium exchange step, and then discarded when the abundance of the mother liquor is very low.
[0016] Preferably, in the synthesis method of the stable isotope-labeled metronidazole, the deuterium source in steps 1) to 3) is methanol-D1, ethanol-D1 or isopropanol-D1. Different deuterated alcohols may exhibit different activities in the reaction, and the selected deuterated alcohol in the present application can optimize the reaction efficiency and product quality, reduce unnecessary side reactions, and improve the purity and selectivity of the product.
[0017] More preferably, in the synthesis method of the stable isotope-labeled metronidazole, the deuterium source is methanol-D1. When methanol-D1 is used as the deuterium source, the purity and selectivity of the product of the present application are optimal.
[0018] Preferably, in the synthesis method of the stable isotope-labeled metronidazole, the catalyst solution in steps 1) and 3) is prepared by mixing a basic catalyst and deuterium water at a molar ratio of 0.45 to 0.55:10.
[0019] Preferably, in the synthesis method of the stable isotope-labeled metronidazole, the catalyst solution in step 2) is prepared by mixing a basic catalyst and deuterium water at a molar ratio of 0.5 to 0.6:15.
[0020] More precise configuration of the catalyst concentration in steps 1) to 3) helps to improve the yield of the product, reduce the residual catalyst, and at the same time ensure the purity and abundance of the product.
[0021] Preferably, in the synthesis method of the stable isotope-labeled metronidazole, the catalyst in steps 1) to 3) is sodium carbonate, potassium carbonate, sodium hydroxide or potassium hydroxide. In the isotope labeling process of the present application, a basic catalyst is used, which has fewer side reactions compared to acidic conditions, thereby improving the purity and yield of the product. Moreover, it can be carried out under relatively mild conditions, which is more conducive to the safety of operation and the stability of the product.
[0022] More preferably, in the synthesis method of the stable isotope-labeled metronidazole, the catalyst in steps 1) to 3) is sodium hydroxide or potassium hydroxide, which has fewer side reactions and higher product abundance.
[0023] Preferably, in the synthesis method of the stable isotope-labeled metronidazole, the deuterated acid in steps 1) to 3) is acetic acid-D1, deuterated hydrochloric acid or deuterated sulfuric acid. Using the preferred deuterated acid to adjust the pH for post-treatment can better maintain the stability of the isotope-labeled substance and avoid loss or conversion of the isotope-labeled substance.
[0024] More preferably, in the synthesis method of the stable isotope-labeled metronidazole, the deuterated acid is acetic acid-D1. The more preferred deuterated acid can better maintain the stability of the isotopically labeled substance and better avoid the loss or conversion of the isotopically labeled substance.
[0025] Preferably, in the synthesis method of the stable isotope-labeled metronidazole, the abundance of the obtained isotopically labeled metronidazole is 97.75% to 99.55%. The deuterated metronidazole obtained by the present application has a much higher abundance than the prior art.
[0026] Compared with the prior art, the synthesis method of the stable isotope-labeled metronidazole of the present application has the beneficial effects that: the present application can obtain stable isotope-labeled metronidazole with high yield and high abundance, the present application effectively reduces the side reactions through multiple hydrogen-deuterium exchange under alkaline conditions, improves the purity and abundance of the isotopically labeled metronidazole, and ensures the quality and stability of the obtained product. The synthesis method precisely controls the temperature, the amount of catalyst, the reaction time and other key parameters, ensuring the effective progress of the reaction and the high quality of the product. The synthesis method realizes high raw material utilization rate, and the obtained product has high purity and high abundance, and is suitable for drug research, biochemical research, medical diagnosis and other fields, and has wide application prospects. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 The nuclear magnetic detection spectrum of the hydrogen-deuterium exchange first product obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure.
[0028] Figure 2 The nuclear magnetic detection spectrum of the hydrogen-deuterium exchange second product obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure.
[0029] Figure 3 The liquid chromatogram of the hydrogen-deuterium exchange second product obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure.
[0030] Figure 4 The mass spectrum of the hydrogen-deuterium exchange second product obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure.
[0031] Figure 5 The nuclear magnetic detection spectrum of the deuterated metronidazole obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure.
[0032] Figure 6 The liquid chromatogram of the deuterated metronidazole obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure.
[0033] Figure 7 The mass spectrum of the deuterated metronidazole obtained after completing the hydrogen-deuterium exchange in the synthesis method of Example 6 of the present application is shown in the figure. Detailed Implementation
[0034] The present invention will be further described below with reference to the accompanying drawings.
[0035] See attached document Figure 1 The isotopic content of the primary hydrogen-deuterium exchange product after one hydrogen-deuterium exchange is (1-0.91 / 3)*100%=69.6%, indicating that the main component of the primary hydrogen-deuterium exchange product is metronidazole-D2.
[0036] Reference Figures 2-4 The isotopic abundances after the second exchange are shown in Table 1.
[0037] Table 1
[0038]
[0039] The isotopic abundance of metronidazole-D3, calculated as the percentage of D atoms at the labeled sites, is as follows:
[0040] D(atom%) = ∑(n·xn) / n = 93.71%
[0041] It is evident that most of the components of the secondary hydrogen-deuterium exchange product obtained after the second hydrogen-deuterium exchange have been converted into metronidazole-D3.
[0042] See attached document Figures 5-7 The isotopic abundances after the third exchange are shown in Table 2.
[0043] Table 2
[0044]
[0045] The isotopic abundance of metronidazole-D3, calculated as the percentage of D atoms at the labeled sites, is as follows:
[0046] D(atom%) = ∑(n·xn) / n = 98.12%
[0047] It is evident that the present invention can obtain high abundance of deuterated metronidazole after three hydrogen-deuterium exchanges.
[0048] The present invention will be further described below with reference to specific embodiments. Embodiment 1 is the preferred embodiment. Example 1
[0049] 1) Primary hydrogen-deuterium exchange: Metronidazole and methanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared by dissolving sodium hydroxide in deuterium water, and the molar ratio of metronidazole, methanol-D1, sodium hydroxide, and deuterium water was 1:10:0.5:10. The reaction was carried out at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0050] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving sodium hydroxide in deuterium water. The molar ratio of the primary hydrogen-deuterium exchange product, methanol-D1, sodium hydroxide, and deuterium water was 1:15:0.5:15. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0051] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by deuterium water with sodium hydroxide, and the molar ratio of the secondary product of hydrogen-deuterium exchange, methanol-D1, sodium hydroxide and deuterium water was 1:10:0.5:10. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 with acetic acid-D1, and the solvent was removed to obtain crude deuterated metronidazole.
[0052] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 72% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 99.55% as determined by LC-MS. Example 2
[0053] 1) Primary hydrogen-deuterium exchange: Metronidazole and isopropanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared by dissolving deuterium in water with sodium hydroxide. The molar ratio of metronidazole, isopropanol-D1, alkaline catalyst and deuterium in water was 1:10:0.5:10. The reaction was carried out at 80°C for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0054] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and isopropanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by adding deuterium water with sodium hydroxide. The molar ratio of the primary hydrogen-deuterium exchange product, isopropanol-D1, sodium hydroxide and deuterium water was 1:15:0.5:15. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 with acetic acid-D1, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0055] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and isopropanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by deuterium water with sodium hydroxide, and the molar ratio of the secondary product of hydrogen-deuterium exchange, isopropanol-D1, sodium hydroxide and deuterium water was 1:10:0.5:10. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 with acetic acid-D1, and the solvent was removed to obtain crude deuterated metronidazole.
[0056] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 69% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 98.65% as determined by LC-MS. Example 3
[0057] 1) Primary hydrogen-deuterium exchange: Metronidazole and methanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared from deuterium water using sodium carbonate, and the molar ratio of metronidazole, methanol-D1, sodium carbonate, and deuterium water was 1:10:0.5:10. The reaction was carried out at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0058] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared from deuterium water with sodium carbonate. The molar ratio of the primary hydrogen-deuterium exchange product, methanol-D1, sodium carbonate and deuterium water was 1:15:0.5:15. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 with acetic acid-D1, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0059] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving sodium carbonate in deuterium water, and the molar ratio of the secondary product of hydrogen-deuterium exchange, methanol-D1, sodium carbonate and deuterium water was 1:10:0.5:10. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 12 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain crude deuterated metronidazole.
[0060] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 69% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 98.72% as determined by LC-MS. Example 4
[0061] 1) Primary hydrogen-deuterium exchange: Metronidazole and methanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared by dissolving potassium hydroxide in deuterium water, and the molar ratio of metronidazole, deuterium source, potassium hydroxide and deuterium water was 1:10:0.45:10. The reaction was carried out at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 11 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0062] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by deuterium water with potassium hydroxide. The molar ratio of the primary hydrogen-deuterium exchange product, deuterium source, potassium hydroxide and deuterium water was 1:15:0.5:15. The reaction was carried out again at 80℃ for 120 min, then cooled to room temperature and allowed to stand for 11 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0063] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by deuterium water with potassium hydroxide, and the molar ratio of the secondary product of hydrogen-deuterium exchange, deuterium source, potassium hydroxide and deuterium water was 1:10:0.45:10. The reaction was carried out again at 80℃ for 125 min, then cooled to room temperature and allowed to stand for 11 h. The pH was adjusted to 6.5 with acetic acid-D1, and the solvent was removed to obtain crude deuterated metronidazole.
[0064] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 68% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 99.01% as determined by LC-MS. Example 5
[0065] 1) Primary hydrogen-deuterium exchange: Metronidazole and methanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared by dissolving deuterium in water with sodium hydroxide. The molar ratio of metronidazole, deuterium source, alkaline catalyst and deuterium in water was 1:10:0.55:10. The reaction was carried out at 80°C for 120 min, then cooled to room temperature and allowed to stand for 13 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0066] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving deuterium in water with sodium hydroxide. The molar ratio of the primary hydrogen-deuterium exchange product, deuterium source, alkaline catalyst and deuterium in water was 1:15:0.6:15. The reaction was carried out again at 80℃ for 115 min, then cooled to room temperature and allowed to stand for 13 h. The pH was adjusted to 6.5 using acetic acid-D1, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0067] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and methanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving deuterium in water with sodium hydroxide. The molar ratio of the secondary product of hydrogen-deuterium exchange, deuterium source, alkaline catalyst and deuterium in water was 1:10:0.55:10. The reaction was carried out again at 80℃ for 115 min, then cooled to room temperature and allowed to stand for 13 h. The pH was adjusted to 6.5 with acetic acid-D1, and the solvent was removed to obtain crude deuterated metronidazole.
[0068] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 67% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 98.86% by LC-MS analysis. Example 6
[0069] 1) Primary hydrogen-deuterium exchange: Metronidazole and ethanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared by dissolving potassium carbonate in deuterium water, and the molar ratio of metronidazole, ethanol-D1, potassium carbonate and deuterium water was 1:8:0.65:8. The reaction was carried out at 75°C for 130 min, then cooled to room temperature and allowed to stand for 15 h. The pH was adjusted to 7 using deuterated sulfuric acid, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0070] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and ethanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving potassium carbonate in deuterium water. The molar ratio of the primary hydrogen-deuterium exchange product, ethanol-D1, potassium carbonate and deuterium water was 1:14:0.65:14. The reaction was carried out again at 75℃ for 130 min, then cooled to room temperature and allowed to stand for 15 h. The pH was adjusted to 7 using deuterated sulfuric acid, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0071] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and ethanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving potassium carbonate in deuterium water, and the molar ratio of the secondary product of hydrogen-deuterium exchange, ethanol-D1, potassium carbonate and deuterium water was 1:7:0.65:7. The reaction was carried out again at 75℃ for 130 min, then cooled to room temperature and allowed to stand for 5 h. The pH was adjusted to 7 with deuterated sulfuric acid, and the solvent was removed to obtain crude deuterated metronidazole.
[0072] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 66% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 98.12% as determined by LC-MS. Example 7
[0073] 1) Primary hydrogen-deuterium exchange: Metronidazole and isopropanol-D1 were added to the reaction vessel, and a catalyst solution was added while stirring. The catalyst solution was prepared by dissolving potassium carbonate in deuterium water, and the molar ratio of metronidazole, isopropanol-D1, potassium carbonate and deuterium water was 1:13:0.35:13. The reaction was carried out at 85℃ for 110 min, then cooled to room temperature and allowed to stand for 10 h. The pH was adjusted to 6 using deuterated hydrochloric acid, and the solvent was removed to obtain the primary hydrogen-deuterium exchange product.
[0074] 2) Secondary hydrogen-deuterium exchange: The primary hydrogen-deuterium exchange product and isopropanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving sodium carbonate in deuterium water, and the molar ratio of the primary hydrogen-deuterium exchange product, isopropanol-D1, sodium carbonate and deuterium water was 1:17:0.35:17. The reaction was carried out again at 85℃ for 110 min, then cooled to room temperature and allowed to stand for 10 h. The pH was adjusted to 6 using deuterated hydrochloric acid, and the solvent was removed to obtain the secondary hydrogen-deuterium exchange product.
[0075] 3) Three-stage hydrogen-deuterium exchange: The secondary product of hydrogen-deuterium exchange and isopropanol-D1 were added to the reaction vessel, and the catalyst solution was added under stirring. The catalyst solution was prepared by dissolving sodium carbonate in deuterium water, and the molar ratio of the secondary product of hydrogen-deuterium exchange, isopropanol-D1, sodium carbonate and deuterium water was 1:12:0.35:12. The reaction was carried out again at 85℃ for 110 min, then cooled to room temperature and allowed to stand for 10 h. The pH was adjusted to 6 with deuterated hydrochloric acid, and the solvent was removed to obtain crude deuterated metronidazole.
[0076] 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain deuterated metronidazole. The yield of this example was calculated to be 64% based on metronidazole. The abundance of deuterated metronidazole obtained in this example was 97.75% as determined by LC-MS.
[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A method for synthesizing stable isotope-labeled metronidazole, characterized in that, The preparation steps are as follows: 1) Primary hydrogen-deuterium exchange: Metronidazole and methanol-D1 are added to the reaction vessel, and a catalyst solution is added while stirring. The catalyst solution is prepared by dissolving an alkaline catalyst in deuterium water. The molar ratio of metronidazole, methanol-D1, alkaline catalyst and deuterium water is 1:8~13:0.45~0.55:
10. The reaction is carried out at 75℃~85℃ for 110min~130min, then cooled to room temperature and allowed to stand for 10h~15h. The pH is adjusted to 6~7 using deuterated acid, and the solvent is removed to obtain the primary hydrogen-deuterium exchange product. 2) Secondary hydrogen-deuterium exchange: The hydrogen-deuterium exchange primary product obtained in step 1) and methanol-D1 are added to the reaction vessel. A catalyst solution is added while stirring. The catalyst solution is prepared by dissolving an alkaline catalyst in deuterium water. The molar ratio of the hydrogen-deuterium exchange primary product, methanol-D1, alkaline catalyst, and deuterium water is 1:14~17:0.5~0.6:
15. The reaction is carried out again at 75℃~85℃ for 110min~130min, then cooled to room temperature and allowed to stand for 10h~15h. The pH is adjusted to 6~7 using deuterated acid, and the solvent is removed to obtain the hydrogen-deuterium exchange secondary product. 3) Three-stage hydrogen-deuterium exchange: The hydrogen-deuterium exchange secondary product obtained in step 2) and methanol-D1 are added to the reaction vessel. A catalyst solution is added under stirring. The catalyst solution is prepared by dissolving an alkaline catalyst in deuterium water. The molar ratio of the hydrogen-deuterium exchange secondary product, methanol-D1, alkaline catalyst, and deuterium water is 1:7~12:0.45~0.55:
10. The reaction is carried out again at 75℃~85℃ for 110min~130min, then cooled to room temperature and allowed to stand for 10h~15h. The pH is adjusted to 6~7 using deuterated acid, and the solvent is removed to obtain crude deuterated metronidazole. 4) The crude deuterated metronidazole was recrystallized from ethanol to obtain pure deuterated metronidazole; In the above steps, the alkaline catalyst is sodium carbonate, potassium carbonate, sodium hydroxide, or potassium hydroxide.
2. The method for synthesizing stable isotope-labeled metronidazole according to claim 1, characterized in that, The deuterated acid mentioned in steps 1) to 3) is acetic acid-D1, deuterated hydrochloric acid, or deuterated sulfuric acid.
3. The method for synthesizing stable isotope-labeled metronidazole according to claim 2, characterized in that, The deuterated acid mentioned is acetic acid-D1.
4. The method for synthesizing stable isotope-labeled metronidazole according to claim 1, characterized in that, The abundance of the obtained deuterated metronidazole was 97.75% to 99.55%.