A compound, and a method of preparing and using the same

Abstract

This invention relates to the field of medicinal chemistry, specifically to a long-acting ester derivative, its preparation method, and its uses. This invention modifies the structure of a parent compound to prepare a prodrug with long-acting properties. This type of drug is formulated into an injectable formulation, forming a drug reservoir in the body from which the drug is slowly, continuously, and stably released and converted into the parent compound, thereby exerting a long-acting effect.

Description

Technical Field

[0001] This invention relates to the field of medicinal chemistry, specifically to a phenylspirocyclohexane long-acting ester derivative, its preparation method, and its uses. Background Technology

[0002] Prodrugs, the active pharmaceutical ingredients of a drug, typically undergo biotransformation in vivo to release the active drug. The use of prodrugs offers several advantages in drug development and therapy. Prodrugs can improve drug bioavailability by enhancing the drug's solubility, stability, and absorption. This can lead to better therapeutic outcomes and more predictable drug delivery. Furthermore, prodrugs can be designed to minimize side effects by targeting the release of the drug to specific tissues or cells. This targeted delivery helps reduce the exposure of non-target tissues to the active drug, thereby reducing adverse reactions. Additionally, prodrugs can improve the chemical stability of the drug, leading to better formulation and storage.

[0003] An important aspect of prodrug development includes prolonging the duration of action: prodrugs can be designed to prolong or sustain the release of the active drug, resulting in a more durable therapeutic effect and potentially reducing the frequency of dosing. A significant benefit may be improved patient compliance or increased patient acceptance, leading to better adherence to medication regimens. Furthermore, it can simplify medication regimens and reduce the burden of medication use.

[0004] Despite these advantages, the design and development of prodrugs requires a thorough understanding of the pharmacokinetics, pharmacodynamics, and metabolism of the parent drug. Furthermore, the chemical structure of the parent drug itself can severely limit the design and feasibility of prodrugs.

[0005] The recently developed Cebranopadol (GRT-6500) (trans-6′-fluoro-4′,9′-dihydro-N,N-dimethyl-4-phenylspiro[cyclohexane-1,1′-(3′H)-pyran[3,4-b]indole]-4-amine) is an analgesic nociceptin / orphanone FQ peptide (NOP) and opioid receptor agonist (WO 2004 / 043967, WO 2008 / 040481, WO2012 / 016703, WO 2012 / 016699, WO 2012 / 016695, WO 2012 / 016698, WO 2012 / 016697, WO2013 / 007361) developed by Grundenthal. Its structural formula is as follows:

[0006] ,

[0007] Cebranopadol exhibits potent analgesic effects in various rat models of acute and chronic pain, including tail-flicking, rheumatoid arthritis, bone cancer, spinal cord ligation, and diabetic neuropathy, with potency 100–1000 times greater than morphine. In these rat models of neuropathic pain, the analgesic effect of cebranopadol is co-mediated by NOPR and classical opioid receptors. Pharmacokinetic studies show that cebranopadol has a half-life of 4.5 h in rats and an oral bioavailability of 13–23% [J Pharmacol Exp Ther. 2014, 349, 535-548]. In non-human primates, cebranopadol's analgesic effect is 5 times that of fentanyl, with an analgesic ED... 50 Ten times the recommended dose does not affect respiratory function. Cebranopadol is addictive, but less so than fentanyl, suggesting a potential for abuse [Anesthesiology. 2021, 135, 482-493]. Currently, cebranopadol is in clinical development in various dosage forms, including oral, immediate-release, and film-coated tablets. In rat tail-flick experiments, intravenous administration of 12 μg / kg cebranopadol provided analgesia for approximately 7 hours; however, severe pain typically could not be relieved in such a short time.

[0008] Therefore, any improvement in prolonging the duration of action of cerebranopadol would be a major breakthrough in medicine, while also providing a more economical treatment system. Prodrug approaches are widely used to prolong the duration of action of rapidly eliminated drugs. Clinically successful examples include haloperidol decanoate, zuclothiasol decanoate, fluphenazine decanoate, paliperidone palmitate, and aripiprazole lauroyl. Broekkamp, ​​C. Letal. (J. Pharm. Pharmacol, Vol. 40, 434, 1988) proposed a long-acting mechanism of action for ester-form prodrugs. They are esterified with fatty acids of varying carbon numbers, leading to increased lipophilicity of the prodrug. Therefore, when the prodrug is injected intramuscularly, the release rate decreases, and the duration of action is prolonged. Ester-form prodrugs are hydrolyzed in vivo by esterases, resulting in an increase in the parent compound. Esterases are present in many tissues and organs, such as blood, brain, liver, heart, lungs, kidneys, and muscles. It has been reported that ester prodrugs and parent compounds have the same pharmacological effects and safety profiles (Gelders, Y. Get al., Int. Clin. Psychopharmacol, Vol. 1, 1, 1986). Summary of the Invention

[0009] This invention modifies the structure of phenylspirocyclohexane to prepare a prodrug with long-acting properties. This type of drug is formulated into a preparation suitable for intramuscular, subcutaneous, or intravenous injection. After intramuscular, subcutaneous, or intravenous injection, it forms a drug reservoir in the body, from which the drug is slowly, continuously, and stably released and converted into phenylspirocyclohexane, thereby exerting a long-acting effect. Specifically, it aims to provide a Cebranopadol ester with a longer duration of action and the same activity as Cebranopadol, thereby expanding its clinical application for patients affected by severe pain. This invention is achieved using the following technical solutions:

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a compound of Formula I or a salt thereof, or a solvate thereof:

[0011] ,

[0012] As an ester group, R can be an optionally substituted straight or branched saturated or unsaturated C1-C2 group. 20 Aliphatic groups, or optionally substituted C6-C6 groups. 10 Aryl group. Preferably, R is an optionally substituted straight-chain or branched C1-C1 group. 20 The alkyl group, wherein the substituent is a C5-C10 heteroaryl, C6-C10 aryl, or H. More preferably, R is a straight-chain or branched C1-C2 group. 20 Alkyl; more preferably, wherein R is C6 to C6. 20 Straight-chain or branched alkyl groups.

[0013] In a preferred embodiment of the present invention, the compound represented by Formula I is any of the following compounds:

[0014] ,

[0015] In another aspect of the present invention, a method for preparing the compound of Formula I or its salt or solvate thereof is provided, comprising steps 1 and 2:

[0016] Step 1: Cebranopadol and paraformaldehyde were reacted with a catalyst and solvent to prepare intermediate 1 (hydroxymethyl Cebranopadol).

[0017] Step 2: The product from Step 1 and C6~C 20 Straight-chain or branched alkyl acyl chlorides are used to prepare crude products of formula I under the action of solvents and acid-binding agents;

[0018] The reaction formula is as follows:

[0019] ,

[0020] Where R is C6~C20 Straight-chain or branched alkyl groups.

[0021] The solvents used in this invention may be selected from, but are not limited to, hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, cyclohexane, petroleum ether, benzene, toluene, and xylene; ether solvents such as dimethyl ether, diethyl ether, diisopropyl ether, methyl tert-butyl ether, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-methoxyethyl ether, and 1,4-dioxane; ester solvents such as methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, n-butyl acetate, and tert-butyl acetate; and polar aprotic solvents such as dimethyl ethyl ether. Amides, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, etc.; chlorinated solvents such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, etc.; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; nitrile solvents such as acetonitrile, propionitrile, isobutyronitrile, etc.; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol or isopropanol, n-butanol, isobutanol, 2-butanol, tert-butanol, ethane-1,2-diol, propane-1,2-diol, etc.; polar solvents such as water, formic acid, acetic acid, etc., or mixtures of any of the above solvents. As a feature of the present invention, the reaction solvent in step 1 is selected from one or more of the following: n-pentane, n-hexane, n-heptane, cyclohexane, petroleum ether, toluene, xylene, dimethyl ether, diethyl ether, isopropyl ether, tetrahydrofuran, methyl acetate, ethyl acetate, dichloromethane, dichloroethane, and chloroform, preferably dichloromethane; the alkaline acid-binding agent is selected from one or more of the following: triethylamine, diisopropylamine, pyridine, sodium acetate, sodium carbonate, and potassium carbonate, preferably triethylamine.

[0022] More specifically, the reaction solvent in step 1 is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, DMSO, acetonitrile, and tetrahydrofuran, preferably N,N-dimethylformamide; the catalyst is selected from cesium carbonate and pyridine DMAP, preferably 4-dimethylaminopyridine (DMAP), and the crystallization temperature is preferably 0-5°C; the reaction solvent in step 2 is selected from one or more combinations of n-pentane, n-hexane, n-heptane, cyclohexane, petroleum ether, toluene, xylene, dimethyl ether, diethyl ether, isopropyl ether, tetrahydrofuran, methyl acetate, ethyl acetate, dichloromethane, dichloroethane, and chloroform, preferably dichloromethane; the basic acid-binding agent is selected from one or more combinations of triethylamine, diisopropylamine, pyridine, sodium acetate, sodium carbonate, potassium carbonate, cesium carbonate, and DBU, preferably triethylamine.

[0023] The compound of formula I synthesized by the above method has been identified by nuclear magnetic resonance (NMR), infrared (IR) and ultraviolet (UV) spectroscopy, gas chromatography / mass spectrometry (GC / MS), and basic analysis. The chromatographic analysis conditions are as follows:

[0024] Table 1 Chromatographic Analysis Conditions

[0025] .

[0026] According to the present invention, the synthetic compounds of Formula I or their solvates can be formulated into various pharmaceutical preparations to provide a long-lasting therapeutic effect. In this regard, the phenylspirocyclohexane ester derivatives of Formula I can be mixed with a selected oil carrier to form a parenteral formulation, whereby the release rate of the target drug, i.e., phenylspirocyclohexane, may be slowed down due to factors such as increased solubility of the target drug in oil. Therefore, longer dosing intervals can be set due to the prolonged duration of action of the target drug. Different dosage forms can then be formulated as needed. Suitable dosage forms for the compounds of Formula I can be oral formulations or injectable oily formulations using sesame oil, soybean oil, or peanut oil as injection carriers. Injectable oily formulations can be administered via intraventricular, intramuscular, subcutaneous, or spinal routes. Nalbuphine prodrugs can also be formulated and administered via transdermal, oral, sublingual, or local routes, such as pastes, ointments, or suppositories.

[0027] This invention provides for the use of compositions of compounds of Formula I or solvates thereof in the preparation of pain medications. The pain refers to one or more of chronic pain, nociceptive pain, neuropathic pain, malignant pain, or inflammatory pain.

[0028] The key points of this invention are:

[0029] This invention discloses a novel phenylspirocyclohexane monoester prodrug derivative, formulated into an injection solution using an oil-based carrier. Upon injection, it cleaves to release phenylspirocyclohexane and a safe and biodegradable component of hexanoic acid, decanoic acid, lauric acid, or palmitic acid. These components not only possess the potent analgesic activity of the original drug but also minimize side effects associated with traditional anesthetics, such as addiction and respiratory depression. Compared to oral phenylspirocyclohexane formulations, this invention offers significant advantages: 1) Long-acting, meaning that when administered parenterally (e.g., intramuscularly), the dosing interval can be changed from every 6 hours to several days or even longer; 2) Overcoming the low first-pass effect of oral administration, resulting in high bioavailability; 3) Caco-2 cell toxicity assays show that the compound of this invention has virtually no toxic effect on this cell type. Attached Figure Description

[0030] Figure 1 The image shows the HPLC chromatogram of compound I-1, phenylspirocyclohexane hexanoate.

[0031] Figure 2 The 1H NMR spectrum is for compound I-1, phenylspirocyclohexane hexanoate.

[0032] Figure 3 This is the carbon spectrum of compound I-1, phenylspirocyclohexane hexanoate.

[0033] Figure 4LC-MS of compound I-1-hexanoic acid phenylspirocyclohexane.

[0034] Figure 5 The 1H NMR spectrum of compound I-3-lauric acid decanoic acid phenylspirocyclohexane.

[0035] Figure 6 This is the carbon spectrum of compound I-3-lauric acid decanoic acid phenylspirocyclohexane.

[0036] Figure 7 LC-MS of compound I-3-lauric acid decanoic acid phenylspirocyclohexane.

[0037] Figure 8 To investigate the toxicity of the compound of this application with Cebranopadol in Caco-2 cells.

[0038] Figure 9 The images show the in vivo pharmacokinetic curves of the compound in this application and Cebranopadol. Detailed Implementation

[0039] The following embodiments can further describe the present invention; however, these embodiments should not be construed as limiting the scope of the present invention.

[0040] Preparation Example: Preparation of Cebranopadol.

[0041] Preparation steps 1+2:

[0042] ,

[0043] 220.00 g of 1,4-cyclohexanedione monoethylene glycol ketal and 583.00 g of methylamine solution (30% ethanol solution) were added to a 1000 ml reaction flask and stirred until dissolved. Then, 440.00 g of anhydrous sodium sulfate was added, and the reaction was carried out at 25–35 °C for 24 hours. After the reaction was completed, the mixture was filtered, the filtrate was concentrated to dryness, and 220 ml of isopropyl ether was added twice to obtain 230.00 g of a black oily substance (intermediate one).

[0044] Add 1000 ml of lithium phenylene solution (1.5 M n-butyl ether solution) to a 3000 ml reaction flask, cool to 0–5 °C, and protect under nitrogen. Then, dissolve 230.00 g of intermediate one in 440 ml of dibutyl ether and slowly add the solution dropwise to the reaction flask, ensuring the addition temperature does not exceed 20 °C, under nitrogen protection. After the addition is complete, heat to room temperature (25–30 °C) and stir for 1 hour. After the reaction is complete, wash once with 440 ml of saturated ammonium chloride solution, wash three times with 440 ml of water, concentrate to dryness at 90 °C, and wash once with 220 ml of isopropanol. Cool to room temperature and dissolve completely in 220 ml of isopropanol. Adjust the pH to 3–4 with 25% isopropanol hydrochloride solution. The mixture was cooled to 0–5 °C and allowed to crystallize for 1 hour. It was then filtered, washed with cold isopropanol (0.5 V), washed with methyl tert-ethyl ether (1.0 V), and dried at 60 °C to give 131.00 g of white solid (intermediate II). The total yield of the two steps was 32.77%.

[0045] Preparation step 3:

[0046] ,

[0047] 130.00 g of intermediate II was dissolved in 260 ml of water and 1300 ml of dichloromethane, and the pH was adjusted to 12-13 with 25% sodium hydroxide solution. The mixture separated into layers, and the organic phase was washed once with 260 ml of water. The organic phase was concentrated to dryness, and 260 ml of isopropanol was added. The temperature was raised to 65°C. 63.00 g of anhydrous formic acid was added dropwise, and after the addition was complete, 70.00 g of formaldehyde solution was quickly added. The mixture was stirred at 65°C for 16 hours. After the reaction was complete, the mixture was concentrated to dryness under vacuum at 85°C. 156 ml of hydrochloric acid and 39 ml of water were added, and the mixture was stirred at 65°C for 3 hours. After the reaction was complete, the mixture was washed once with 260 ml of isopropyl ether. The temperature was lowered to 0-5°C, and the pH was adjusted to 12-13 with 25% sodium hydroxide solution. The mixture was extracted with 1300 ml of dimethyltetrahydrofuran, washed once with 260 ml of water, and concentrated to dryness. 117 ml of isopropanol and 78 ml of water were added, and the mixture was stirred until dissolved. The solution was cooled to 0–5 °C and allowed to crystallize for 1 hour. After filtration, the solution was washed with 65 ml of cold isopropanol-water mixture and dried at 60 °C to obtain 45.41 g of off-white solid (intermediate tri), with a yield of 45.62%.

[0048] Preparation step 4:

[0049] ,

[0050] 70.00 g ammonium chloride and 930 ml water were added to a 3000 ml reaction flask and stirred until dissolved. Then, 500 ml of 2-methyltetrahydrofuran and 100 g of 4-fluorophenylhydrazine hydrochloride were added, and the mixture was heated to 70 °C. 43.11 g of 2,3-dihydrofuran was dissolved in 480 ml of 2-methyltetrahydrofuran and then slowly added dropwise to the reaction flask. The mixture was stirred at 70 °C for 16 hours. The mixture was cooled to 50 °C, and the layers separated; the aqueous phase was discarded. The organic phase was washed once with 700 ml of 5% sodium chloride solution. The organic phase was concentrated to dryness, and 600 ml of toluene and 250 ml of water were added and stirred until the layers separated; the aqueous phase was discarded. The organic phase was concentrated to remove half of the solid, cooled to 0–5 °C, and crystallized for 5 hours. The crystals were filtered, washed with 50 ml of cold toluene solution, and dried at 40 °C to give 59.70 g of a reddish-brown solid (intermediate tetrahydrofuran), with a yield of 54.17%.

[0051] Preparation step 5:

[0052] ,

[0053] 45.00 g of intermediate III, 37.11 g of intermediate IV, and 2250 ml of dichloromethane were added to a 3000 ml reaction flask, and the mixture was cooled to 0–5 °C. 55.23 g of trimethylsilyl trifluoromethanesulfonate was dissolved in 45 ml of dichloromethane and quickly added to the reaction flask. After addition, the mixture was stirred at 0–5 °C for 20 minutes. The temperature was then raised to room temperature (25–30 °C), and the reaction was stirred for 3 hours. After the reaction was complete, the mixture was concentrated to remove approximately 3 / 4 of the dichloromethane, and then 765 ml of 1 N sodium hydroxide solution and 450 ml of water were added. The mixture was stirred and cooled to 0–5 °C, and crystallization was allowed to occur for 1 hour. The crystals were filtered, and the filter cake was slurried with 450 ml of isopropanol, filtered again, and dried at 60 °C to obtain 75.00 g of a white solid (intermediate V), with a yield of 95.70%.

[0054] Example 1: Preparation of compound I-1.

[0055] .

[0056] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0057] 5.0 g of hydroxymethyl cebranopadol, 3.76 g of triethylamine, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 4.18 g of hexanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 4.3 g of hexanoyl cebranopadol, with a yield of 69.34%.

[0058] Example 2: Preparation of compound I-1.

[0059] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0060] 5.0 g of hydroxymethyl cebranopadol, 3.56 g of DBU, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 4.18 g of hexanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.3 g of hexanoyl cebranopadol, with a yield of 53.21%.

[0061] Example 3: Preparation of compound I-1.

[0062] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0063] 5.0 g of hydroxymethyl cebranopadol, 3.23 g of DIPEA, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 4.18 g of hexanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.44 g of hexanoyl cebranopadol, with a yield of 55.47%.

[0064] Example 4: Preparation of compound I-1.

[0065] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0066] 5.0 g of hydroxymethyl cebranopadol, 3.89 g of pyridine, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 4.18 g of hexanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.88 g of hexanoyl cebranopadol, with a yield of 62.56%.

[0067] MS (ESI): M+H + 507.1,

[0068] 1H NMR (400MHz, Chloroform-d): δ7.44~7.31 (m, 6H), 7.17 (dd, J = 9.1,2.5 Hz, 1H), 7.00 (d, J = 2.5 Hz, 1H), 6.41 (s, 2H), 3.98 (t, J = 5.3 Hz, 2H), 2.79 (t, J = 5.3 Hz, 2H), 2.55 (d, J = 13.2 Hz, 2H), 2.45~2.29 (m, 4H), 2.12 (s, 6H), 2.04~1.91 (m, 4H), 1.64 (t, J = 7.4 Hz, 2H), 1.30 (dt, J =7.8, 3.8 Hz, 4H), 0.93~0.86 (m, 3H).

[0069] 13 CNMR (151MHz, CDCl3): δ173.38, 159.37, 157.81, 140.98, 139.00, 133.47,127.92, 127.86, 127.44, 126.69, 126.58, 110.41, 110.28, 103.69, 103.53,72.64, 67.99, 58.95, 58.19, 37.63, 34.14, 31.19, 30.34, 28.62, 24.54, 22.72,22.24, 13.84.

[0070] Example 5: Preparation of compound I-2.

[0071] .

[0072] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0073] 5.0 g of hydroxymethyl cebranopadol, 3.76 g of triethylamine, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 5.92 g of decanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 4.1 g of decanoyl cebranopadol, with a yield of 59.60%.

[0074] Example 6: Preparation of compound I-2.

[0075] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0076] 5.0 g of hydroxymethyl cebranopadol, 3.76 g of DIPEA, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 5.92 g of decanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 4.05 g of decanoyl cebranopadol, with a yield of 58.88%.

[0077] Example 7: Preparation of compound I-2.

[0078] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0079] 5.0 g of hydroxymethyl cebranopadol, 3.16 g of pyridine, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 5.92 g of decanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to give 4.31 g of decanoyl cebranopadol, with a yield of 62.65%.

[0080] Example 8: Preparation of compound I-2.

[0081] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0082] 5.0 g of hydroxymethyl cebranopadol, 3.22 g of DBU, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 5.92 g of decanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.96 g of decanoyl cebranopadol, with a yield of 57.57%.

[0083] MS (ESI): M+H + 563.77;

[0084] 1H NMR (400MHz, Chloroform-d): δ7.46~7.30 (m, 6H), 7.18 (dd, J = 9.1, 2.5 Hz, 1H), 6.99 (td, J = 9.0, 2.5 Hz, 1H), 6.42 (s, 2H), 3.98 (t, J = 5.3Hz, 2H), 2.79 (t, J = 5.3 Hz, 2H), 2.54 (d, J = 13.2 Hz, 2H), 2.46~2.30 (m,4H), 2.13 (s, 6H), 2.03~1.92 (m, 4H), 1.36~1.25 (m, 12H), 0.91 (t, J = 6.7Hz, 3H).

[0085] 13 C NMR (151MHz, CDCl3): δ173.36, 159.37, 157.81, 140.97, 138.99, 133.46,130.46, 127.93, 127.83, 126.63, 126.60, 121.52, 110.28, 103.68, 72.63, 67.99,58.94, 58.19, 37.63, 34.19, 31.88, 30.32, 29.58, 29.57, 29.42, 29.30,, 29.05,, 28.40, 24.86, 22.71, 14.10.

[0086] Example 9: Preparation of compound I-3.

[0087] .

[0088] 2.0 g of Cebranopadol, 3.55 g of paraformaldehyde, 0.13 g of DMAP, and 10 ml of DMF were added to a 50 ml reaction flask and heated to 50–60 °C for 6 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 200 ml of water (3 times each), dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 2:1) to give 0.63 g of hydroxymethyl Cebranopadol, with a yield of 29.18%.

[0089] 0.60 g of hydroxymethyl cebranopadol, 0.22 g of triethylamine, and 20 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 0.48 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 1 hour. After the reaction was complete, the mixture was washed three times with 10 ml of water, dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 0.42 g of lauroyl cebranopadol, with a yield of 48.40%.

[0090] Example 10: Preparation of compound I-3.

[0091] 2.0 g of Cebranopadol, 3.55 g of paraformaldehyde, 5.25 g of cesium carbonate, and 10 ml of DMF were added to a 50 ml reaction flask and heated to 50–60 °C for 10 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 200 ml of water (3 x 200 ml), dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 2:1) to give 0.11 g of hydroxymethyl Cebranopadol, with a yield of 5.09%.

[0092] 0.10 g of hydroxymethyl cebranopadol, 0.08 g of triethylamine, and 20 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 0.18 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 1 hour. After the reaction was complete, the mixture was washed three times with 10 ml of water, dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 0.08 g of lauroyl cebranopadol, with a yield of 55.32%.

[0093] Example 11: Preparation of compound I-3.

[0094] 2.0 g of Cebranopadol, 3.55 g of paraformaldehyde, 1.13 g of pyridine, and 10 ml of DMF were added to a 50 ml reaction flask and heated to 50–60 °C for 5 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 200 ml of dichloromethane and 200 ml of water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 2:1) to give 0.35 g of hydroxymethyl Cebranopadol, with a yield of 16.21%.

[0095] 0.30 g of hydroxymethyl cebranopadol, 0.12 g of triethylamine, and 20 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 0.28 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 1 hour. After the reaction was complete, the mixture was washed three times with 10 ml of water, dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to give 0.23 g of lauroyl cebranopadol, with a yield of 53.01%.

[0096] Example 12: Preparation of compound I-3.

[0097] 2.0 g of Cebranopadol, 2.55 g of paraformaldehyde, 0.54 g of DBU, and 10 ml of DMF were added to a 50 ml reaction flask and heated to 50–60 °C for 5 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 200 ml of dichloromethane and 200 ml of water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 2:1) to give 0.45 g of hydroxymethyl Cebranopadol, with a yield of 20.85%.

[0098] 0.40 g of hydroxymethyl cebranopadol, 0.22 g of triethylamine, and 20 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 0.48 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 1 hour. After the reaction was complete, the mixture was washed three times with 10 ml of water, dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to give 0.33 g of lauroyl cebranopadol, with a yield of 57.04%.

[0099] Example 13: Preparation of compound I-3.

[0100] 20.0 g of Cebranopadol, 35.47 g of paraformaldehyde, 1.31 g of DMAP, and 100 ml of DMF were added to a 500 ml reaction flask and heated to 50–60 °C for 16 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 300 ml of dichloromethane and 200 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and recrystallized from 120 ml of methanol to give 6.81 g of hydroxymethyl Cebranopadol, with a yield of 31.54%.

[0101] 6.80 g of hydroxymethyl cebranopadol, 5.12 g of triethylamine, and 34 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 9.24 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 400 ml of dichloromethane was added, and the mixture was washed three times with 300 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.3 g of lauroyl cebranopadol (yield 33.55%).

[0102] Example 14: Preparation of compound I-3.

[0103] 20.0 g of Cebranopadol, 35.47 g of paraformaldehyde, 1.31 g of DMAP, and 100 ml of DMF were added to a 500 ml reaction flask and heated to 50–60 °C for 16 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 300 ml of dichloromethane and 200 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and recrystallized from 100 ml of methanol to give 6.59 g of hydroxymethyl Cebranopadol, with a yield of 30.53%.

[0104] 6.50 g of hydroxymethyl cebranopadol, 4.90 g of triethylamine, and 30 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 8.84 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 400 ml of dichloromethane was added, and the mixture was washed three times with 300 ml of water (3 x 3 ml). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to give 3.42 g of lauroyl cebranopadol, with a yield of 36.38%.

[0105] Example 15: Preparation of compound I-3.

[0106] 34.40 g of Cebranopadol, 61.00 g of paraformaldehyde, 2.26 g of DMAP, and 170 ml of DMF were added to a 500 ml reaction flask and heated to 50–60 °C for 16 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 200 ml of water (3 times each), dried over anhydrous sodium sulfate, concentrated, dissolved in 500 ml of methanol, concentrated to approximately 150 ml, cooled to 0–5 °C for 2 hours to crystallize, and filtered to obtain 28.84 g of hydroxymethyl Cebranopadol, with a yield of 77.67%.

[0107] 6.50 g of hydroxymethyl cebranopadol, 4.90 g of triethylamine, and 30 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 8.84 g of lauroyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 400 ml of dichloromethane was added, and the mixture was washed three times with 300 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.53 g of lauroyl cebranopadol (yield 37.55%).

[0108] MS (ESI): M+H + 591.4;

[0109] 1 H NMR(400MHz,Chloroform-d)δ7.45~7.31 (m, 6H), 7.17 (dd, J = 9.1,2.5 Hz, 1H), 6.99 (td, J = 9.0, 2.5 Hz, 1H), 6.41 (s, 2H), 3.98 (t, J = 5.3Hz, 2H), 2.79 (t, J = 5.3 Hz, 2H), 2.55 (d, J = 13.2 Hz, 2H), 2.47~2.30 (m,4H), 2.12 (s, 6H), 2.03~1.92 (m, 4H), 1.35~1.25 (m, 18H), 0.91 (t, J = 6.7Hz, 3H).

[0110] 13 C NMR (151MHz, CDCl3) δ173.38, 159.36, 157.80, 140.97, 138.99, 133.46,130.46, 127.92, 127.85, 126.68, 126.58, 121.53, 110.27, 103.68, 72.63, 67.98,58.94, 58.19, 37.63, 34.18, 31.89, 30.33, 29.59, 29.56, 29.43, 29.30, 29.19,29.05, 28.61, 28.40, 24.86, 22.71, 14.09.

[0111] Example 16: Preparation of compound I-4.

[0112] .

[0113] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was complete, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.16%.

[0114] 5.0 g of hydroxymethyl cebranopadol, 3.76 g of triethylamine, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 6.18 g of palmitoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 5.3 g of palmitoyl cebranopadol, with a yield of 67.03%.

[0115] Example 17: Preparation of compound I-4.

[0116] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was completed, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.13%.

[0117] 5.0 g of hydroxymethyl cebranopadol, 3.56 g of DBU, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 5.88 g of palmitoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.56 g of palmitoyl cebranopadol, with a yield of 45.02%.

[0118] Example 18: Preparation of compound I-4.

[0119] 100g Cebranopadol, 177.33g paraformaldehyde, 6.56g DMAP, and 6000ml DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was completed, the mixture was filtered, and the filtrate was washed three times with 1000ml dichloromethane and 500ml water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to obtain 69.26g of hydroxymethyl Cebranopadol, with a yield of 64.13%.

[0120] 5.0 g of hydroxymethyl cebranopadol, 3.23 g of DIPEA, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 4.18 g of hexanoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.44 g of palmitoyl cebranopadol, with a yield of 43.50%.

[0121] Example 19: Preparation of compound I-4.

[0122] 100g of Cebranopadol, 177.33g of paraformaldehyde, 6.56g of DMAP, and 6000ml of DMF were added to a 1000ml reaction flask and heated to 50-60℃ for 24 hours. After the reaction was completed, the mixture was filtered, and the filtrate was washed three times with 1000ml of dichloromethane and 500ml of water (3 times each). The filtrate was dried over anhydrous sodium sulfate, concentrated, dissolved in 1000ml of methanol, and concentrated to approximately 500ml. The solution was cooled to 0-5℃ for 2 hours to crystallize, and then filtered to give 69.26g of a white solid (hydroxymethyl Cebranopadol), with a yield of 64.16%.

[0123] 5.0 g of hydroxymethyl cebranopadol, 3.89 g of pyridine, and 25 ml of dichloromethane were added to a 50 ml reaction flask, and the mixture was cooled to 0–5 °C. 6.88 g of palmitoyl chloride was slowly added dropwise, with the addition temperature not exceeding 10 °C. After the addition was complete, the mixture was heated to room temperature and stirred for 3 hours. After the reaction was complete, 200 ml of dichloromethane was added, and the mixture was washed three times with 100 ml of water (3 times each). The solution was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent: PE:EA = 10:1) to obtain 3.66 g of palmitoyl cebranopadol, with a yield of 46.29%.

[0124] MS (ESI): M+H + 647.93;

[0125] 1H NMR(400MHz,Chloroform-d)δ7.45~7.30 (m, 6H), 7.18 (dd, J = 9.1,2.5 Hz, 1H), 6.99 (td, J = 9.0, 2.5 Hz, 1H), 6.42 (s, 2H), 3.99 (t, J = 5.3Hz, 2H), 2.79 (t, J = 5.3 Hz, 2H), 2.56 (d, J = 13.2 Hz, 2H), 2.46~2.31 (m,4H), 2.13 (s, 6H), 2.04~1.92 (m, 4H), 1.35~1.22 (m, 26H), 0.91 (t, J = 6.7Hz, 3H).

[0126] 13 C NMR (151MHz, CDCl3) δ173.38, 159.36, 157.80, 140.97, 138.99, 133.46,130.46, 127.92, 127.85, 126.68, 126.58, 121.53, 110.27, 103.68, 72.63, 67.98,58.94, 58.19, 37.63, 34.18, 31.89, 30.33, 29.59, 29.56, 29.43, 29.32,29.30,29.25, 29.19, 29.05, 28.61, 28.51, 28.40, 24.86, 24.66, 22.71, 14.09.

[0127] Example 20: Preparation of a typical injection solution.

[0128] Prescription 1:

[0129] .

[0130] 2. Preparation method:

[0131] Dissolve compounds I-1 to I-4 and Cebranopadol in a specific ratio of benzyl benzoate and sesame oil according to the prescribed dosage, and gently shake to ensure complete dissolution. Fill 1 ml ampoules and sterilize at 121°C for 15 minutes.

[0132] Example 21: Detection of toxicity in Caco-2 cells

[0133] The MTT assay is a commonly used method for detecting the impact of samples on cell survival and growth. MTT is a yellow dye, its full name being 3-(4,5-dimethylthiazol-2)-2,5-diphenyltetrazolium bromide. The detection principle is that succinate dehydrogenase present in the mitochondria of living cells can reduce MTT to formazan, a water-insoluble, blue-purple crystal that deposits in the cell; dead cells do not have this function. Formazan is dissolved in DMSO solution, and its absorbance is measured using an enzyme-linked immunosorbent assay (ELISA) reader at 490 nm or 570 nm. Within a certain cellular range, the number of viable cells is directly proportional to the amount of formazan formed. Referring to the values ​​of the blank control group, the number of viable cells in the experimental group can be indirectly reflected. The specific experimental steps are as follows:

[0134] 1) Take Caco-2 cells that are in normal growth stage and in the logarithmic growth phase, digest them with trypsin to form a single cell suspension, and adjust the concentration of the Caco-2 cell suspension to 1×10⁻⁶. 4 cell / mL;

[0135] 2) Spread the cell suspension evenly into a 96 cell culture plate, add 100 μL to each well, and fill the edge wells with 100 μL of PBS buffer. Incubate the plate at 37°C in a 5% CO2 cell culture incubator.

[0136] 3) After 24 hours of culture, observe the cell state under a microscope; the cells show uniform monolayer growth. Carefully aspirate the old culture medium from each well and add different concentrations of Cebranopadol and its compounds I-1 to I-4 to each well. The final concentrations of Cebranopadol and its compounds I-1 to I-4 in each experimental group were 2.3, 18.56, 74.1, 148.2, 296.4, and 592.8 μmol / L, respectively. Each concentration group had three replicates. Control wells (containing an equal volume of Caco-2 cell suspension, without drug administration) and zeroing wells (containing no cells, no drug administration, and 100 μL of an equal volume of culture medium) were also included. The cells were then placed in a cell culture incubator for further culture.

[0137] 4) After culturing for 4 hours, discard the old culture medium, add fresh culture medium, and add 20 μL of MTT solution (5 mg / mL) to each well of the 96-well plate under dark conditions, and incubate in an incubator.

[0138] 5) After incubating for 4 h, gently remove the 96-well plate from the incubator, carefully aspirate the liquid from each well, add 150 μL of DMSO solution, and shake on a shaker at 37 °C for 10–15 min to completely dissolve the blue-purple crystals.

[0139] 6) Use an ELISA reader to measure the absorbance (OD) value of each well at a wavelength of 490 nm, and calculate the cell inhibition rate of each experimental group:

[0140] The results showed that after 4 hours of treatment with Cebranopadol and its compounds I-1 to 4 at concentrations of 2.3, 18.56, 74.1, 148.2, 296.4, and 592.8 μmol / L, the survival rate of Caco-2 cells could still reach over 80%, indicating that the drugs had almost no toxic effects on the cells within this uptake time and concentration range.

[0141] Example 22: In vivo pharmacokinetic study.

[0142] One male beagle of ordinary grade was used. The dogs were fasted for 12 hours prior to administration, but had free access to water. The formulation from Example 21 was administered intramuscularly at a dose of 0.16 mg / kg Cebranopadol (equivalent to 0.21 mg / kg, 0.24 mg / kg, 0.25 mg / kg, and 0.33 mg / kg for compounds I-1, I-2, I-3, and I-4, respectively). Blood samples (approximately 1.0 mL) were collected from the beagle's forelimb vein before administration and at 0.083, 0.25, 0.5, 1, 2, 4, 6, 8, 12, 24, 36, 48, 96, 144, and 168 hours after administration. The blood was placed in a heparinized centrifuge tube, centrifuged at 6000 rpm for 10 min at 4°C, and the plasma was separated and stored at -80°C for analysis.

[0143] Plasma sample preparation: The sample was prepared in an ice bath. Take 40 μL of methanol, 15 μL of internal standard (bicalutamide 2.6 μg / mL, dissolved in 50% methanol), add 300 μL of plasma sample, vortex mix, add 5 mL of ethyl acetate, vortex mix, centrifuge at 9000g for 3 min, take the organic phase and evaporate to dryness under vacuum, redissolve in 150 μL of methanol, and inject 20 μL for analysis.

[0144] Experimental results: Pharmacokinetic curves of each formulation in beagle dogs showed that the compounds of the present invention could be released stably, achieving a long-acting release effect.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The compound represented by formula (Ⅰ) or its salt: ， Where R is C6~C 20 Straight-chain or branched alkyl groups.

2. Compounds or their salts with the following structures: 。 3. A method for preparing the compound represented by Formula I or a salt thereof according to claim 1, characterized in that: Includes the following steps: Step 1: Cebranopadol and paraformaldehyde were reacted with a catalyst and solvent to prepare intermediate 1, namely hydroxymethyl Cebranopadol; Step 2: The product from Step 1 and C6~C 20 Straight-chain or branched alkyl acyl chlorides are used to prepare crude products of formula I under the action of solvents and acid-binding agents; The reaction formula is as follows: , Where R is C6~C 20 Straight-chain or branched alkyl groups.

4. A method for preparing the compound of formula I or a salt thereof according to claim 3, characterized in that: The reaction solvent in step 1 is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, DMSO, acetonitrile, and tetrahydrofuran; the catalyst is selected from cesium carbonate, pyridine, or DMAP; the reaction solvent in step 2 is selected from one or more combinations of n-pentane, n-hexane, n-heptane, cyclohexane, petroleum ether, toluene, xylene, dimethyl ether, diethyl ether, isopropyl ether, tetrahydrofuran, methyl acetate, ethyl acetate, dichloromethane, dichloroethane, and chloroform; the acid-binding agent is selected from one or more combinations of triethylamine, diisopropylamine, pyridine, sodium acetate, sodium carbonate, potassium carbonate, cesium carbonate, and DBU.

5. The method for preparing the compound of formula I or a salt thereof as described in claim 4, characterized in that, The reaction solvent in step 1 is selected from N,N-dimethylformamide.

6. The method for preparing the compound of formula I or a salt thereof as described in claim 4, characterized in that, The catalyst was selected from DMAP.

7. The method for preparing the compound of formula I or a salt thereof as described in claim 4, characterized in that, The reaction solvent in step 2 is selected from dichloromethane.

8. The method for preparing the compound of formula I or a salt thereof as described in claim 4, characterized in that, The acid-binding agent is selected from triethylamine.

9. A pharmaceutical composition comprising the compound of any one of claims 1 to 2 or a salt thereof, and a pharmaceutically acceptable carrier.

10. The pharmaceutical composition of claim 9, formulated for intramuscular, intradermal, or subcutaneous injection.

11. The pharmaceutical composition according to claim 9, characterized in that, The pharmaceutical composition is an injectable oily preparation using sesame oil, soybean oil, or peanut oil as the injection carrier.

12. Use of the composition of claim 9 in the preparation of a medicament for treating pain.

13. Use of the composition of claim 12, wherein pain refers to one or more of chronic pain, nociceptive pain, neuropathic pain, malignant pain, or inflammatory pain.

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