A radioactive isotope carbon-14 labeled methoprene and its preparation method
By preparing the reaction of [cyano-14C](R)-7-methoxy-3,7-dimethyloctannitrile, [aldehyde-14C]citronellal and Phosphalide reagent, the radioisotope carbon-14 labeled eneme was synthesized, which solved the problem of lack of tracer in eneme research, achieved high purity and firm labeling, and supported in-depth research of eneme in organisms and environment.
Patent Information
- Application Number
- CN202411874604.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2044-12-19
AI Technical Summary
The lack of effective radiotracers in existing studies on enesters has led to insufficient research on its absorption, distribution, transfer and environmental behavior in plants.
The radioisotope carbon-14 labeled enester was synthesized by reaction steps such as preparation of [cyano-14C](R)-7-methoxy-3,7-dimethyloctitrile, [aldehyde-14C]citronellal and phosphorus lid reagent through inert gas protection, acid-base buffer solvents and aprotic solvents.
The prepared radioisotope carbon-14 labeled enester has clear marking sites in the enester molecule, high release purity and chemical purity, concise synthesis steps, firm nuclide labeling and not easy to fall off, providing accurate trace information, supporting research in organisms and environments.
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Figure CN119320323B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of radiochemical synthesis, and particularly to a radioactive isotope carbon-14 labeled methoprene (E,E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2,4-dienoic acid isopropyl ester and a preparation method thereof. Background Art
[0002] Methoprene ((E,E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2,4-dienoic acid isopropyl ester), as a biochemical insecticide, due to its high activity, relative target organism specificity and good environmental safety, a large number of products have been developed, evaluated and promoted for controlling various pests. As an external insecticide, methoprene has target organism specificity and extremely high juvenile hormone activity. By disrupting or interfering with the hormone balance in insects, larvae cannot complete growth metamorphosis and sexual maturity and die, and it can also cause infertility in adults, thereby reducing the pest population.
[0003] Currently, research on the absorption, distribution, transfer, residue of methoprene in plants and its environmental behavior in water and soil rarely involves the metabolites / degradates of methoprene. In other words, current research on the metabolic process and environmental behavior of methoprene is still not deep enough. And radioactive isotope carbon-14 labeled methoprene [(E,E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2,4-dienoic acid isopropyl ester] is a necessary radioactive tracer for studying its safety and effectiveness in plant experiments and pharmacokinetics (tissue distribution, metabolite structure identification, mass balance, etc.). Summary of the Invention
[0004] The purpose of the present invention is to provide a radioactive isotope carbon-14 labeled methoprene and a preparation method thereof to solve the problems of lack of effective radioactive tracers in the existing research on methoprene and insufficient research on the metabolic process and environmental behavior.
[0005] In a first aspect, the present technical solution provides a preparation method of a radioactive isotope carbon-14 labeled methoprene, including the following steps:
[0006] S1: Prepare [cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile:
[0007] Under the protection of an inert gas at 0 - 60°C, dissolve 4-methylbenzenesulfonic acid-(2R)-6-methoxy-2,6-dimethylheptyl ester in a polar aprotic solvent, add an inorganic base and stir, and then add [carbon- 14C] Sodium cyanide was stirred until the reaction ended, a fat-soluble solvent was added for liquid separation, the organic solution layer was taken for drying and concentration, and [cyano- 14 C] (R)-7-methoxy-3,7-dimethyloctanenitrile was obtained through flash column chromatography;
[0008] S2: Preparation of [formyl- 14 C] citronellal:
[0009] At a reaction temperature of 0 - 50 °C, [cyano- 14 C] (R)-7-methoxy-3,7-dimethyloctanenitrile and Raney Ni were reacted in a buffer solution of acid and base until the reaction ended, a fat-soluble solvent was added for liquid separation, the organic solution layer was taken for drying and concentration, and [formyl- 14 C] citronellal was obtained through flash column chromatography;
[0010] S3: Preparation of carbon-14 labeled methoprene:
[0011] Under the protection of an inert gas and in the dark at 0 - 50 °C, [formyl- 14 C] citronellal, a phosphonium ylide reagent, and 18-crown-6 were placed in an aprotic solvent and reacted until the reaction ended, a fat-soluble solvent was added for liquid separation, the organic solution layer was taken for drying and concentration, and carbon-14 labeled methoprene was obtained through flash column chromatography.
[0012] The radioactive isotope carbon-14 in the carbon-14 labeled methoprene prepared by this scheme is labeled on the 7-position carbon atom of the aliphatic chain in the methoprene molecule. The structural formula of the prepared radioactive isotope carbon-14 labeled methoprene is: [(E,E)-(RS)-isopropyl 11-methoxy-3,7,11-trimethyldodeca-2,4-dienoate]. The chemical formula of the radioactive isotope carbon-14 labeled methoprene is shown in the following formula (I), where the asterisk indicates the labeling position of the isotope carbon-14:
[0013] .
[0014] The labeling site of the isotope carbon-14 in the radioactive isotope carbon-14 labeled methoprene synthesized by this scheme is determined, and it has the advantages of high radiochemical purity and chemical purity, short synthesis steps, firm labeling of the nuclide carbon-14 in the methoprene molecule, and not easy to fall off, which can meet the requirements of tracer experiments in organisms and the environment.
[0015] In step S1, the sulfonate group in 4-methylbenzenesulfonic acid-(2R)-6-methoxy-2,6-dimethylheptyl ester has good leaving ability. Under alkaline conditions, an inorganic base takes the cyanide anion from the carbon-14 labeled sodium cyanide to make it a nucleophile. The cyanide anion attacks the carbon atom of the sulfonate group, and a nucleophilic substitution reaction occurs to generate [cyano-14 C](R)-7-methoxy-3,7-dimethyloctanenitrile. Throughout the reaction process, polar aprotic solvents are beneficial for the progress of nucleophilic substitution reactions. They can make the reactants dissolve and disperse better, and at the same time stabilize the reaction transition state.
[0016] Specifically, in some embodiments, the polar aprotic solvent in step S1 is selected from one or more combinations of DMSO, DMF, and THF, and preferably DMSO.
[0017] The inorganic base in step S1 is selected from one or more combinations of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium bicarbonate, and potassium bicarbonate, and preferably sodium hydroxide.
[0018] The [carbon- 14 C] cyanide in step S1 includes one or more combinations selected from [carbon- 14 C] sodium cyanide, [carbon- 14 C] potassium cyanide, [carbon- 14 C] copper cyanide, [carbon- 14 C] zinc cyanide.
[0019] The lipophilic solvent in step S1 is selected from one or more combinations of ethyl acetate, isopropyl acetate, dichloromethane, chloroform, petroleum ether, diethyl ether, and benzene, and preferably ethyl acetate.
[0020] The [cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile obtained in step S1 has the chemical structural formula shown in the following formula (II), where the asterisk indicates the labeling position of isotope carbon-14:
[0021] .
[0022] In some embodiments, in step S1, carbon-14-labeled sodium cyanide is added and stirred for 1 to 24 h. After monitoring that there are no free cyanide ions in the reaction solution with a cyanide detection reagent, pure water is added to terminate the reaction. The advantage of doing this is that it can ensure that the reaction has proceeded sufficiently. If there are still free cyanide ions in the reaction solution, it means that the reaction has not ended and there is still remaining carbon-14-labeled sodium cyanide, and the reaction needs to continue to increase the yield of the target product [cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile; at the same time, it can also avoid the occurrence of side reactions. After the target reaction is basically completed, excessive cyanide ions may react with other substances to cause unnecessary side reactions.
[0023] In step S2 of this solution, [cyano- 14C](R)-7-methoxy-3,7-dimethyloctanenitrile undergoes a hydrogenation reduction reaction of the cyano group under the catalysis of Raney Ni. Raney Ni provides active hydrogen atoms. The cyano group is first reduced to an imine intermediate, and then the imine intermediate is further reduced to an aldehyde group, obtaining [aldehyde group- 14 C] citronellal. The pyridine - acetic acid - water mixed solvent acts as an acid - base buffer solvent, regulating the pH value of the reaction system, enabling the reaction to proceed in a suitable acid - base environment, and at the same time helping to stabilize the reaction intermediates and the activity of the catalyst.
[0024] In some embodiments, the acid - base buffer solvent includes, but is not limited to, pyridine - acetic acid - aqueous solutions of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphite, and sodium hypophosphite. Specifically, in some embodiments, [cyano - 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile and sodium hypophosphite monohydrate are stirred in a mixed solvent, where the mixed solvent is a reagent composed of pyridine, acetic acid, and water.
[0025] In some embodiments, the reaction temperature in step S2 is 0 - 25 °C.
[0026] In some embodiments, the lipophilic solvent in step S2 is selected from one or more combinations of ethyl acetate, isopropyl acetate, dichloromethane, chloroform, petroleum ether, diethyl ether, and benzene, and preferably ethyl acetate.
[0027] In some embodiments, after adding Raney Ni and reacting for 1 - 24 h, pure water is added to terminate the reaction.
[0028] The [aldehyde group- 14 C] citronellal obtained in step S2 has the structural formula shown in formula (III) below, where the asterisk indicates the labeling position of isotope carbon - 14:
[0029] .
[0030] In step S3 of this scheme, the phosphonium ylide reagent generates a carbanion under basic conditions. This carbanion has strong nucleophilicity. The aldehyde group of [aldehyde group- 14 C] citronellal acts as an electrophilic center and undergoes a Wittig reaction (coupling reaction) with the carbanion generated by the phosphonium ylide reagent. The addition of 18 - crown - 6 can complex the cations in the reaction system, enhance the basicity of the inorganic base, promote the generation of the phosphonium ylide reagent and the progress of the reaction. The reaction generates carbon - 14 labeled methoprene. The aprotic solvent is beneficial to the reaction, can dissolve the reactants and intermediates, and promotes the smooth progress of the reaction.
[0031] In some embodiments, a phosphonium ylide reagent is dissolved in a non-polar solvent, and then an inorganic base and 18-crown-6 are added thereto, followed by stirring to obtain a reaction solution. [Aldehydo- 14 C] citronellal is dissolved in an aprotic solvent and added to the reaction solution for reaction.
[0032] In some embodiments, the aprotic solvent is selected from one of benzene and toluene.
[0033] In some embodiments, the non-polar solvent in step S3 is selected from one or a combination of two or more of benzene, toluene, chloroform, dichloroethane, and carbon tetrachloride, and preferably benzene.
[0034] In some embodiments, the inorganic base in step S3 is selected from one or a combination of two or more of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium bicarbonate, and potassium bicarbonate, and preferably sodium hydroxide.
[0035] In some embodiments, the reaction solution is added under light-shielded conditions and stirred for 3 to 24 h until the reaction ends, and then water is added to terminate the reaction.
[0036] In some embodiments, the fat-soluble solvent in step S3 is selected from one or a combination of two or more of ethyl acetate, isopropyl acetate, dichloromethane, chloroform, petroleum ether, ether, and benzene, and preferably ethyl acetate.
[0037] In a second aspect, the present solution provides a radioisotope carbon-14 labeled methoprene prepared by the preparation method of the radioisotope carbon-14 labeled methoprene according to the above, and the structural formula is shown in the following formula (I):
[0038] .
[0039] The radioisotope carbon-14 labeled site of the radioisotope carbon-14 labeled methoprene in the present solution is on the aliphatic chain of methoprene.
[0040] Compared with the prior art, the present technical solution has the following characteristics and beneficial effects:
[0041] This solution innovatively provides a preparation method for radiolabeled methoprene with radioactive isotope carbon-14, filling the gap in the relevant field. Each step in the preparation process is closely linked. By carefully selecting solvents, reagents, and reaction conditions, high reaction efficiency and product purity are ensured. At the level of reaction principle, the chemical properties of various substances are cleverly utilized, such as the leaving property of the sulfonate group, the catalytic hydrogenation of Raney Ni, and the nucleophilicity of the phosphonium ylide reagent, etc., to achieve precise labeling. In practical applications, the prepared labeled methoprene has a clear labeling site, high radiochemical purity and chemical purity, a simple synthesis step, and the radionuclide labeling is firm and not easy to fall off. This enables it to provide accurate and reliable tracer information when studying the behavior of methoprene in organisms and the environment, providing a powerful tool for in-depth exploration of the metabolic process, environmental behavior, and pharmacokinetics of methoprene, etc., and contributing to the development of related field research, such as optimizing the use strategy of methoprene in agricultural pest control, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Figure 1 is the nuclear magnetic spectrum of [cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile synthesized in this example.
[0043] Figure 2 is the nuclear magnetic spectrum of [aldehyde group- 14 C]citronellal synthesized in this example.
[0044] Figure 3 is the nuclear magnetic spectrum of the radiolabeled methoprene with radioactive isotope carbon-14 synthesized in this example. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.
[0046] The following illustrates the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0047] Example 1 Synthesis of Radiolabeled Methoprene with Radioactive Isotope Carbon-14
[0048] The reaction equation of this Example 1 is as follows:
[0049] 。
[0050] S1: Synthesize cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile;
[0051] Under nitrogen protection, sodium hydroxide (40 mg, 1.0 mmol) and [carbon- 14 C] sodium cyanide (102 mg, 2.0 mmol) were added to DMSO (5 mL), and (2R)-6-methoxy-2,6-dimethylheptyl 4-methylbenzenesulfonate (662.9 mg, 2.02 mmol) was dissolved in DMSO (1 mL) and added to the reaction solution. The mixture was stirred at 25 °C for 18 h. After detecting that there was no free cyanide ion in the reaction solution with a cyanide detection reagent, water (18 mL) was added, and the mixture was extracted four times with ethyl acetate (20 mL). The combined organic phases were dried and concentrated to dryness. The residue was purified by a silica gel column with a diameter of 5 cm and a mass of 20 g (300 - 400 mesh). The eluents were PE (150 mL), PE:EA = 20:1 (250 mL), and PE:EA = 10:1 (100 mL), with a flow rate of 1 mL / s. The effluent of PE:EA = 20:1 was collected and concentrated to dryness to obtain cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile (325.4 mg, 1.77 mmol, 88.42% yield). The NMR spectrum of the cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile synthesized in this example is as follows Figure 1 shown.
[0052] Step S2: Synthesize aldehyde- 14 C] citronellal:
[0053] At 25 °C, cyano- 14C](R)-7-Methoxy-3,7-dimethyloctanenitrile (104.5 mg, 0.568 mmol) and sodium hypophosphite monohydrate (362.0 mg, 3.408 mmol) were dissolved in 3 mL of a mixed solvent of pyridine - acetic acid - water (4:2:1) and stirred rapidly. Raney Ni (0.42 mL) stored in water was added rapidly. After stirring for 30 minutes, a second batch of Raney Ni (0.2 mL) stored in water was added. After reacting for 3 h, pure water was added to terminate the reaction. The mixture was extracted six times with ethyl acetate (10 mL). The combined organic phases were dried and concentrated to dryness. It was purified on a silica gel column with a diameter of 5 cm and 20 g (300 - 400 mesh). The eluents were PE (100 mL), PE:EA = 20:1 (200 mL), and PE:EA = 10:1 (150 mL), with a flow rate of 1 mL / s. The effluents of PE:EA = 20:1 (200 mL) and PE:EA = 10:1 (150 mL) were collected and concentrated to dryness to obtain [aldehyde group - 14 C]Citronellal (74.6 mg, 0.397 mmol, 69.86% yield). The NMR spectrum of [aldehyde group - 14 C]citronellal synthesized in this example is as Figure 2 shown.
[0054] Step S3: Synthesis of carbon - 14 labeled methoprene:
[0055] Under nitrogen protection, the phosphonium ylide reagent (435.9 mg, 1.425 mmol) was dissolved in benzene (2 mL), potassium hydroxide (122.9 mg, 2.192 mmol) and 18 - crown - 6 (57.6 mg, 0.218 mmol) were added. It was stirred rapidly at 25 °C for 5 minutes. [Aldehyde group - 14 C]citronellal (206.0 mg, 1.096 mmol) was dissolved in benzene (1 mL), and it was slowly added dropwise into the reaction solution in the dark. After reacting in the dark at 25 °C for 18 h, the reaction was terminated. The mixture was extracted ten times with ethyl acetate (5 mL). The combined organic phases were dried and concentrated to dryness. It was purified on a silica gel column with a diameter of 5 cm and 20 g (300 - 400 mesh). The eluents were PE (200 mL) and PE:EA = 10:1 (200 mL), with a flow rate of 1 mL / s. The effluent of PE:EA = 10:1 (150 mL) was collected and concentrated to dryness to obtain carbon - 14 labeled methoprene (264.0 mg, 0.846 mmol, 77.20% yield); among which (Z) - carbon - 14 labeled methoprene is 14% and (E) - carbon - 14 labeled methoprene is 86%. The NMR spectrum of the carbon - 14 labeled methoprene synthesized in this example is as Figure 3 shown.
[0056] It will be understood that the term "a" should be construed as "at least one" or "one or more". That is, in one embodiment, the number of an element may be one, while in other embodiments, the number of the element may be multiple. The term "a" should not be construed as a limitation on the quantity.
[0057] The present invention is not limited to the above-described optimal embodiments. Any person can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has a technical solution that is the same as or similar to the present application, it falls within the protection scope of the present invention.
Claims
1. A preparation method of radioisotope carbon-14 labeled methoprene, characterized in that, It includes the following steps: S1: Prepare [cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile: Under the protection of inert gas at 0-60℃, 4-methylbenzenesulfonic acid (2R)-6-methoxy-2,6-dimethylheptyl ester was dissolved in a polar aprotic solvent, and an inorganic base was added and stirred, and then [carbon- 14 C] sodium cyanide was stirred for 1 to 24 hours. After monitoring the reaction solution with a cyanide detection reagent to determine if there was no free cyanide ion, pure water was added to terminate the reaction. A fat-soluble solvent was added to separate the liquids. The organic solution layer was dried and concentrated, and [cyano- 14 C] (R) -7-methoxy-3,7-dimethyloctanonitrile, wherein [cyano- 14 The chemical structure of (R)-7-methoxy-3,7-dimethyloctanonitrile is shown in the following formula (II): ； S2: Prepare [aldehyde group- 14 C] citronellal: At a reaction temperature of 0 to 50 °C, [cyano- 14 C](R)-7-methoxy-3,7-dimethyloctanenitrile and Raney Ni are reacted in an acid-base buffer solution until the reaction is complete. A fat-soluble solvent is added for liquid separation, and the organic solution layer is taken for drying and concentration. Flash column chromatography is used to obtain [aldehyde group- 14 C] citronellal. The [aldehyde group- 14 C] citronellal obtained in step S2 has the structural formula shown in the following formula (III): ； S3: Prepare carbon-14 labeled methoprene: Under the protection of inert gas and in the dark at 0 - 50 °C, [aldehyde group- 14 C] citronellal, a phosphorus ylide reagent, and 18-crown-6 are placed in an aprotic solvent and reacted until the reaction is complete. A fat-soluble solvent is added for liquid separation, and the organic solution layer is taken for drying and concentration. Carbon-14 labeled methoprene is obtained by flash column chromatography. The radioactive isotope carbon-14 of the radioactive isotope carbon-14 labeled methoprene is labeled on the 7-position carbon atom of the aliphatic chain in the methoprene molecule, and the structural formula is shown as the following formula (I): 。 2. The preparation method of the radioisotope carbon-14 labeled methoprene according to claim 1, wherein The polar aprotic solvent in step S1 is selected from one or more combinations of DMSO, DMF, and THF; the inorganic base is selected from one or more combinations of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium bicarbonate, and potassium bicarbonate.
3. The preparation method of the radioisotope carbon-14 labeled methoprene according to claim 1, wherein [Carbon- 14 C] cyanides are selected from [carbon- 14 C] sodium cyanide, [carbon- 14 C] potassium cyanide, [carbon- 14 C] copper cyanide, [carbon- 14 C] zinc cyanide, or a combination of two or more thereof.
4. The preparation method of radioisotope carbon-14 labeled methoprene according to claim 1, characterized in that, The acid-base buffer solvent includes, but is not limited to, pyridine-acetic acid-aqueous solutions of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphite, and sodium hypophosphite.
5. The preparation method of the radioisotope carbon-14 labeled methoprene according to claim 1, wherein Dissolve the phosphonium ylide reagent in a nonpolar solvent, add an inorganic base and 18-crown-6, and stir to obtain a reaction solution. Then dissolve [aldehyde group- 14 C] citronellal in an aprotic solvent and add it to the reaction solution for reaction.
6. The preparation method of radioisotope carbon-14 labeled methoprene according to claim 1, wherein, The aprotic solvent in step S3 is selected from one of benzene and toluene.