CN106866733B

CN106866733B - Levo meptazinol prodrug and preparation method and application thereof

Info

Publication number: CN106866733B
Application number: CN201611129691.0A
Authority: CN
Inventors: 向家宁; 徐雪松; 冯己
Original assignee: Kerry Corning Bioengineering Wuhan Co ltd
Current assignee: Kerry Corning Bioengineering Wuhan Co ltd
Priority date: 2015-12-11
Filing date: 2016-12-09
Publication date: 2020-11-20
Anticipated expiration: 2036-12-09
Also published as: CN106866733A

Abstract

The invention provides a levorotation meptazinol prodrug, a preparation method and application thereof, wherein the levorotation meptazinol prodrug is a compound shown in a formula I or a stereoisomer, a geometric isomer, a tautomer, a nitrogen oxide, a hydrate, a solvate, a metabolite or a pharmaceutically acceptable salt of the compound shown in the formula I. The compound has low liver first pass effect and high bioavailability, and the medicine containing the compound as active component can be used for treating neurodegenerative diseases or various acute and chronic pains, such as wound, postoperative, obstetric and cancer pains, migraine and neuropathic pain.

Description

Levo meptazinol prodrug and preparation method and application thereof

PRIORITY INFORMATION

This application claims priority and benefit to patent application No. 201510920412.1 filed on 11/12/2015 with the chinese national intellectual property office, and is incorporated herein by reference in its entirety.

Technical Field

The invention relates to the field of biomedicine, in particular to a levomeptazinol prodrug and a preparation method and application thereof.

Background

Meptazino1 is an effective analgesic with small side effects, has a chiral center in the molecule, and is marketed as hydrochloride of racemate in 1986, and has been accepted in the British pharmacopoeia in 1998 because of its positive therapeutic effect. Compared with other opioid analgesics, the side effects such as respiratory depression and addiction are extremely low, so the opioid analgesic does not belong to the category of 'narcotics' management. Meanwhile, two optical enantiomers of meptazinol show different biological activities, especially on the inhibition of acetylcholinesterase (AChE), the activity of the levorotatory body is far higher than that of the dextrorotatory body.

Prodrug design of a well-known effective drug is an effective method in innovative drug research. The prodrug research takes the existing drugs as lead compounds, and the structure of the lead compounds is modified to optimize the pharmacokinetic and pharmacodynamic properties of the lead compounds. By the method, the absorption of the medicament can be improved, the toxicity and adverse reaction of the medicament can be reduced, the action time of the medicament can be effectively prolonged by utilizing the existing slow release technology, the targeting property of the medicament can be enhanced, and the like. The prodrug compound is easy to prepare, and has the advantages of low investment, low risk and the like.

Currently, meptazinol prodrugs are awaiting further development.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.

The present invention has been completed based on the following findings of the inventors:

the liver first-pass effect of meptazinol is serious, after oral absorption, phenolic hydroxyl is rapidly acidified or sulfated by glucuronate at the liver, so that water-soluble metabolites are formed and are discharged in urine, and the bioavailability is not high and is only about 8%.

Meanwhile, research has found that the inhibitory activity of (-) -meptazinol (levomeptazinol) on AChE is far greater than that of (+) -meptazinol (dextro-meptazinol).

Based on the problems and the findings, the inventor carries out appropriate chemical modification on the levorotation meptazinol, so that the levorotation meptazinol is connected with other groups through chemical bonds to form a temporary chemical combination, thereby changing or modifying the physicochemical property of the levorotation meptazinol and effectively preventing the formation of a phenolic hydroxyl combination. In the invention, the inventor provides the levorotatory meptazinol ester prodrug and the preparation method thereof, the levorotatory meptazinol ester prodrug molecule is converted into levorotatory meptazinol to play a role through enzymatic or non-enzymatic chemical reaction in vivo, and the levorotatory meptazinol ester prodrug can effectively reduce the first pass effect of the liver and improve the bioavailability of the levorotatory meptazinol.

In a first aspect of the invention, the invention features a compound. According to an embodiment of the invention, the compound is a compound of formula I or a stereoisomer, a geometric isomer, a tautomer, a nitric oxide, a hydrate, a solvate, a metabolite, or a pharmaceutically acceptable salt of a compound of formula I,

wherein R is an ester group, and the compound shown in the formula I is a levo-meptazinol ester prodrug molecule. According to the embodiment of the invention, the compound provided by the invention effectively prevents the formation of phenolic hydroxyl conjugate, effectively reduces the first pass effect of liver, and improves the bioavailability of levomeptazinol.

According to an embodiment of the invention, the above-mentioned compounds may further have at least one of the following additional technical features:

according to an embodiment of the present invention, the ester group includes at least one selected from a phosphate group, a carbonate group, and an aminocarbonate group. According to the embodiment of the invention, the compound containing the ester group (levo-meptazinol ester prodrug molecule) effectively avoids the formation of a phenolic hydroxyl conjugate, effectively reduces the first pass effect of the liver, and improves the bioavailability of the levo-meptazinol.

In a second aspect of the invention, the invention provides a process for the preparation of the above compound. According to an embodiment of the invention, the method comprises: carrying out esterification reaction on the compound shown in the formula II to obtain the compound shown in the formula I,

wherein, the compound shown in the formula II is levo-meptazinol. According to the embodiment of the invention, the levorotation meptazinol is subjected to esterification reaction, so that a levorotation meptazinol ester prodrug molecule is obtained, the levorotation meptazinol ester prodrug molecule effectively reduces the first pass effect of the liver, and the bioavailability of the levorotation meptazinol is improved.

According to an embodiment of the present invention, the above method for preparing a compound may further have at least one of the following additional technical features:

according to some embodiments of the invention, when R in the compound of formula I is a phosphate group, the method comprises: contacting the compound shown in the formula II with phosphorus oxychloride, triethylamine and ethanol to generate a compound shown in the formula III,

wherein the contacting is performed in dichloromethane and the compound of formula III is a phosphate ester levomeptazinol prodrug molecule. Phosphorus oxychloride is a phosphate group-introducing compound. According to the embodiment of the invention, the phosphate ester levomeptazinol prodrug molecule prepared by the method shields phenolic hydroxyl, and has the characteristics of low liver first pass effect and high bioavailability.

According to some embodiments of the invention, when R in the compound of formula I is a phosphate group, the method further comprises: adding phosphorus oxychloride into the first anhydrous dichloromethane, and cooling to 0-5 ℃ to obtain a solution A; adding the compound shown in the formula II and triethylamine into second anhydrous dichloromethane, and uniformly mixing to obtain a solution B; dropwise adding the solution B to the solution A, and then reacting at 0 ℃ for 1 hour to obtain a solution C; adding ethanol into the solution C, naturally heating to room temperature, and reacting for 0.5 hour under a stirring state to obtain a solution D; and sequentially concentrating and purifying the solution D to obtain a compound shown as a formula III, wherein the using ratio of the first anhydrous dichloromethane, the phosphorus oxychloride, the second anhydrous dichloromethane, the compound shown as the formula II, the triethylamine and the ethanol is 3ml to 1.1mmol to 1ml to 0.9mmol to 4.3mmol to 2 ml. According to the embodiment of the invention, phosphate groups are introduced into levorotation meptazinol by the method, and the obtained phosphate ester levorotation meptazinol prodrug molecules can be rapidly hydrolyzed into raw medicine levorotation meptazinol by the widely existing phosphatase in a human body to play a role, so that the bioavailability is improved.

In a third aspect of the invention, the invention provides the use of the levorotatory meptazinol ester prodrug molecule in the preparation of a medicament for treating neurodegenerative diseases or acute and chronic pain.

According to an embodiment of the invention, the acute and chronic pain comprises trauma, postoperative, obstetric and cancer pain, migraine or neuropathic pain.

According to an embodiment of the invention, the neurodegenerative disease includes alzheimer's disease and parkinson's disease.

According to the embodiment of the invention, the levomeptazinol ester prodrug molecule provided by the invention is used for preparing a medicine, the medicine is used for treating neurodegenerative diseases or a series of pain diseases, including various acute and chronic pains, such as wound, postoperative, obstetric and cancer pains, migraine, neuropathic pain and the like, and has a remarkable curative effect.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1-2 show pain response charts for the mechanical hyperalgesia test according to one embodiment of the present invention;

figure 3 shows the results of comparing the anti-allodynic effects of levomeptazinol at different doses and at different time points, according to one embodiment of the present invention.

Detailed Description

The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention.

Compound (I)

wherein R is an ester group, and the compound shown in the formula I is a levo-meptazinol ester prodrug molecule. According to the embodiment of the invention, the solubility of the compound provided by the invention is not obviously different from that of the levomeptazinol, the compound has good chemical stability and enzyme metabolic activity, and the compound can be converted into the levomeptazinol to play a role through an enzymatic chemical reaction in vivo, so that the compound provided by the invention effectively prevents the formation of a phenolic hydroxyl conjugate, effectively lightens the first pass effect of the liver, and improves the bioavailability of the levomeptazinol.

Process for preparing compounds

wherein, the compound shown in the formula II is levo-meptazinol. According to the embodiment of the invention, levorotation meptazinol is subjected to esterification reaction, so that levorotation meptazinol ester prodrug molecules are obtained, the levorotation meptazinol ester prodrug molecules have better water solubility, chemical stability and enzyme metabolic activity, and compared with original medicine levorotation meptazinol, the levorotation meptazinol ester prodrug molecules can effectively shield the phenolic hydroxyl of parent molecules, effectively reduce the first pass effect of the liver, and effectively improve the bioavailability.

According to some embodiments of the present invention, the esterification reaction may be carried out by contacting the compound of formula II with a compound selected from phosphorus oxychloride or a derivative thereof. Phosphorus oxychloride or a derivative thereof and levomeptazinol are subjected to esterification reaction, so that phosphate ester levomeptazinol prodrug molecules are obtained.

The following describes in detail the method for preparing the levomeptazinol prodrug molecule of the present invention, taking the preparation of the phosphate levomeptazinol prodrug molecule as an example:

process for the preparation of phosphate ester levomeptazinol prodrug molecules (compounds of formula III)

According to an embodiment of the present invention, when R in the compound of formula I is a phosphate group, the method comprises: contacting the compound shown in the formula II with phosphorus oxychloride, triethylamine and ethanol to generate a compound shown in the formula III,

According to an embodiment of the present invention, when R in the compound of formula I is a phosphate group, the method further comprises: adding phosphorus oxychloride into the first anhydrous dichloromethane, and cooling to 0-5 ℃ to obtain a solution A; adding the compound shown in the formula II and triethylamine into second anhydrous dichloromethane, and uniformly mixing to obtain a solution B; dropwise adding the solution B to the solution A, and then reacting at 0 ℃ for 1 hour to obtain a solution C; adding ethanol into the solution C, naturally heating to room temperature, and reacting for 0.5 hour under a stirring state to obtain a solution D; and sequentially concentrating and purifying the solution D to obtain a compound shown as a formula III, wherein the using ratio of the first anhydrous dichloromethane, the phosphorus oxychloride, the second anhydrous dichloromethane, the compound shown as the formula II, the triethylamine and the ethanol is 3ml to 1.1mmol to 1ml to 0.9mmol to 4.3mmol to 2 ml. According to the embodiment of the invention, phosphate groups are introduced into levo-meptazinol by the method, so that the membrane penetration capacity of the medicine can be improved, the stability of the medicine is increased, the action time of the medicine is prolonged, and the elimination rate of the surface of the medicine is reduced; the phosphate ester levo-meptazinol prodrug molecule prepared by the method can be rapidly hydrolyzed into raw levo-meptazinol by the widely existing phosphatase in a human body to play a role, and the bioavailability can be effectively improved.

Use of compounds for the preparation of medicaments

It is noted that levomeptazinol has significant inhibitory activity against acetylcholinesterase, and has extremely low side effects such as respiratory depression and addiction, and significant analgesic effect. The levo-meptazinol ester prodrug molecule provided by the invention has the same drug effect as levo-meptazinol, but the bioavailability is obviously improved, so that the levo-meptazinol ester prodrug molecule provided by the invention is used for preparing a medicine, the medicine is used for treating neurodegenerative diseases or a series of pain diseases, including various acute and chronic pains, such as wound, postoperative, obstetric and cancer pains, migraine, neuropathic pain and the like, and the curative effect is obviously improved on the premise of taking the same dose.

In another aspect of the present invention, the present invention provides a pharmaceutical composition for treating neurodegenerative diseases or a series of pain diseases, comprising a levomeptazinol ester prodrug molecule or a pharmaceutically acceptable salt as an active ingredient. Therefore, the pharmaceutical composition can be used for effectively treating neurodegenerative diseases or a series of pain diseases, including various acute and chronic pains, such as wound, postoperative, obstetric and cancer pains, migraine, neuropathic pain and the like.

According to some embodiments of the present invention, the pharmaceutical composition comprising the levomeptazinol ester prodrug molecule of the present invention may further comprise a pharmaceutically acceptable carrier, and the dosage form and administration mode of the pharmaceutical composition are not particularly limited. For oral administration, the pharmaceutically acceptable carrier may include binders, lubricants, disintegrants, excipients, solubilizers, dispersants, stabilizers, suspending agents, colorants and flavoring agents. For injectable formulations, pharmaceutically acceptable carriers may include buffers, preservatives, analgesics, solubilizers, isotonic agents (isotonics agents) and stabilizers. For formulations for topical administration, pharmaceutically acceptable carriers may include bases, excipients, lubricants and preservatives. The pharmaceutical composition of the present invention may be prepared in various dosage forms in combination with the above pharmaceutically acceptable carrier. For example, for oral administration, the pharmaceutical compositions may be prepared as tablets, troches, capsules, elixirs, suspensions, syrups or wafers. For injectable preparations, the pharmaceutical compositions may be prepared in ampoules, e.g. in single dose dosage form, or in unit dosage forms, e.g. in multidose containers. The pharmaceutical compositions may also be formulated as solutions, suspensions, tablets, pills, capsules and depot preparations.

Among the carriers suitable for pharmaceutical formulations, according to some specific examples of the present invention, are excipients and diluents that may include: lactose, glucose, sucrose, sorbitol, mannitol, xylitol, erythritol, maltitol, starch, gum arabic, alginate, gelatin, calcium phosphate, calcium silicate, cellulose, methylcellulose, microcrystalline cellulose, polyvinylpyrrolidone, water, methyl hydroxybenzoate, propylhydroxybenzoate, talc, magnesium stearate, and mineral oil.

According to other embodiments of the present invention, fillers, anticoagulants, lubricants, moisturizers, fragrances, and preservatives may also be included in the pharmaceutical compositions of the present invention.

According to the embodiment of the invention, the levorotation meptazinol ester prodrug molecule and the pharmaceutical composition taking the levorotation meptazinol ester prodrug molecule as the active ingredient can inhibit the activity of acetylcholinesterase, and have low respiratory inhibition and addiction side effects, so that the medicine taking the levorotation meptazinol ester prodrug molecule as the active ingredient and the pharmaceutical composition containing the levorotation meptazinol ester prodrug molecule can be administered in the treatment of neurodegenerative diseases or a series of pain diseases, including various acute and chronic pains, such as trauma, postoperative, obstetric and cancer pains, migraine and neuropathic pain.

The term "administering" as used herein means introducing a predetermined amount of a substance into a patient by some suitable means. The drug of the present invention having the levomeptazinol ester prodrug molecule as an active ingredient can be administered by any common route as long as it can reach the desired tissue. Various modes of administration are contemplated, including peritoneal, intravenous, intramuscular, subcutaneous, cortical, oral, topical, nasal, pulmonary and rectal, but the invention is not limited to these exemplified modes of administration. However, because of oral administration, the active ingredients of orally administered compositions should be coated or formulated to prevent degradation in the stomach. In addition, the pharmaceutical compositions of the present invention may be administered using a specific device that delivers the active ingredient to the target cells.

The administration frequency and dose of the pharmaceutical composition of the present invention can be determined by a number of relevant factors, including the type of disease to be treated, the administration route, the age, sex, body weight and severity of the disease of the patient and the type of drug as an active ingredient. According to some embodiments of the invention, the daily dose may be divided into 1, 2 or more doses in a suitable form for administration 1, 2 or more times over the entire period, as long as a therapeutically effective amount is achieved.

The term "therapeutically effective amount" refers to an amount of a compound sufficient to significantly ameliorate some of the symptoms associated with a disease or condition, i.e., to provide a therapeutic effect for a given condition and administration regimen. For example, in treating neurodegenerative diseases or labor, a drug or compound that reduces, prevents, delays, inhibits or retards any symptom of the disease or disorder should be therapeutically effective. A therapeutically effective amount of a drug or compound need not cure a disease or condition, but will provide treatment for a disease or condition such that the onset of the disease or condition in an individual is delayed, prevented or prevented, or the symptoms of the disease or condition are alleviated, or the duration of the disease or condition is altered, or the disease or condition becomes less severe, or recovery is accelerated, for example.

The term "treatment" is used to refer to obtaining a desired pharmacological and/or physiological effect. The effect may be prophylactic in terms of complete or partial prevention of the disease or symptoms thereof, and/or may be therapeutic in terms of a partial or complete cure for the disease and/or adverse effects resulting from the disease. As used herein, "treatment" encompasses treatment of a disease (primarily neurodegenerative disease or pain) in a mammal, particularly a human, including: (a) preventing disease (e.g., preventing neurodegenerative disease) or the occurrence of a disorder in an individual who is susceptible to the disease but has not yet been diagnosed with the disease; (b) inhibiting a disease, e.g., arresting disease progression; or (c) alleviating the disease, e.g., alleviating symptoms associated with the disease. As used herein, "treatment" encompasses any administration of a drug or compound to a subject to treat, cure, alleviate, ameliorate, reduce or inhibit a disease in the subject, including, but not limited to, administering a drug comprising a levomeptazinol ester prodrug molecule as described herein as an active ingredient to a subject in need thereof.

According to an embodiment of the present invention, the drug or pharmaceutical composition of the present invention having the levomeptazinol ester prodrug molecule as an active ingredient may be used in combination with conventional treatment methods and/or therapies, or may be used separately from conventional treatment methods and/or therapies. When the drug or pharmaceutical composition of the present invention comprising the levomeptazinol ester prodrug molecule as an active ingredient is administered in combination therapy with other drugs, they may be administered to the individual sequentially or simultaneously. Alternatively, the pharmaceutical compositions of the invention may comprise a combination of the levomeptazinol ester prodrug molecule of the invention, a pharmaceutically acceptable carrier or pharmaceutically acceptable excipient, and other therapeutic or prophylactic agents known in the art.

The scheme of the invention will be explained with reference to the examples. It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

EXAMPLE 1 preparation of phosphate ester levomeptazinol prodrug molecule (Compound XW10091)

Wherein, the compound shown in the formula III is phosphate ester levo-meptazinol prodrug molecule, which is also called as compound XW 10091.

(1) To 3mL of anhydrous Dichloromethane (DCM) was added 0.2g (1.1mmol) of phosphorus oxychloride (POCl)₃) Cooling to 0-5 deg.C with ice water bath;

(2) to 1mL of anhydrous dichloromethane was added 0.2g (0.9mmol) of levomeptazinol as a solid

And 0.4g (4.3mmol) of triethylamine are uniformly mixed, and then the mixture is dripped into the dichloromethane solution of phosphorus oxychloride obtained in the step (1) to react for 1 hour at 0 ℃;

(3) adding 2mL of ethanol (EtOH) into the solution obtained in the step (2), naturally heating to room temperature,

stirring and reacting for 0.5 hour;

(4) and (4) sequentially concentrating the solution obtained in the step (3), and performing neutral preparation, separation and purification to obtain 160mg of phosphate ester levo-meptazinol prodrug molecules with the yield of 51%.

Phosphate ester levo-meptazinol prodrug molecule¹H NMR and MS (ESI) analytical data are as follows:

¹H NMR(400MHz,DMSO-d₆)＝7.32(t,J＝7.8Hz,1H),7.18-7.14(m,2H),7.00(d,J＝8.0Hz,1H),4.17-4.10(m,4H),2.78(d,J＝14.0Hz,1H),2.64-2.37(m,3H),2.30(s,3H),2.03-1.98(m,1H),1.75-1.49(m,6H),1.48-1.34(m,1H),1.24(t,J＝7.4Hz,6H),0.51(t,J＝7.4Hz,3H)；MS(ESI):370.2[M+1]⁺。

EXAMPLE 2 preparation of levomeptazinol prodrug molecule (Compound XW10093)

To 4mL of anhydrous dichloromethane was added 0.16g (1.0mmol) of phosphorus oxychloride, and the mixture was cooled to 0-5 ℃ with an ice water bath. 0.2g (0.86mmol) of levomeptazinol and 0.4g (4.3mmol) of triethylamine are added into 1mL of anhydrous dichloromethane, after uniform mixing, the mixture is dripped into a dichloromethane solution of phosphorus oxychloride for reaction for 1 hour at 0 ℃, 2mL of water is added, the temperature is naturally raised to room temperature, the mixture is stirred for 0.5 hour, and the mixture is concentrated to prepare and purify 0.2g of light yellow oily matter with the yield of 75 percent.

¹H NMR(400MHz,D₂O)＝7.47(t,J＝8.2Hz,1H),7.37-7.23(m,2H),7.23-7.10(m,1H),3.85(d,J＝14.4Hz,1H),3.61(d,J＝14.4Hz,1H),3.23(t,J＝6.0Hz,2H),2.89(s,3H),2.49(dd,J＝6.0,14.4Hz,1H),2.02-1.83(m,3H),1.82-1.50(m,4H),0.61(t,J＝7.4Hz,3H)；MS(ESI):314.4[M+1]⁺。

EXAMPLE 3 preparation of levomeptazinol prodrug molecule (Compound XW10187)

The compound XW10187 is levorotation meptazinol prodrug molecule: levo meptazinol ethyl carbonate.

0.3g (1.3mmol) of levomeptazinol and 195.0mg (1.9mmol) of triethylamine are dissolved in 6mL of dichloromethane to form a homogeneous solution. The solution was cooled to 0 ℃ with an ice-water bath and 167.0mg (1.5mmol) of ethyl chloroformate were added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 16 hours, and then diluted with 10mL of dichloromethane. The diluted reaction solution was washed with 10mL of water and 10mL of brine in this order. The organic phase was collected, dried, filtered and concentrated to give an oil, which was chromatographed on silica gel column (petroleum ether: ethyl acetate 5/1-1/1) to give 280.0mg of an oil. This oil was dissolved in 2mL of ethyl acetate hydrochloride solution (concentration about 2M) and stirred at 25 ℃ for 16 hours to precipitate a pale yellow solid, which was filtered and dried to obtain 150.0mg of a pale yellow solid compound as the hydrochloride salt of the product in 34% yield.

¹H NMR(400MHz,D₂O)＝7.55(t,J＝8.0Hz,1H),7.41(d,J＝7.6Hz,1H),7.31(s,1H),7.19(d,J＝8.4Hz,1H),4.33(q,J＝7.0Hz,2H),3.85(d,J＝14.4Hz,1H),3.62(d,J＝14.0Hz,1H),3.22(t,J＝5.8Hz,2H),2.86(s,3H),2.45(dd,J＝4.8,14.8Hz,1H),2.04-1.49(m,7H),1.34(t,J＝7.2Hz,3H),0.57(t,J＝7.2Hz,3H)；MS(ESI):306.3[M+1]⁺。

EXAMPLE 4 preparation of levomeptazinol prodrug molecule (Compound XW10190)

The compound XW10190 is levorotatory meptazinol prodrug molecule: levo-meptazinol isopropyl carbonate.

0.2g (0.86mmol) of levomeptazinol and 95.4mg (0.9mmol) of triethylamine were dissolved in 2mL of dichloromethane to form a homogeneous solution. The solution was cooled to 0 ℃ with an ice-water bath and 115.5mg (0.9mmol) of isopropyl chloride were added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 16 hours, and then diluted with 10mL of dichloromethane. The diluted reaction solution was washed with 10mL of water and 10mL of brine in this order. The organic phase was collected, dried, filtered and concentrated to give an oil, which was chromatographed on silica gel column (petroleum ether: ethyl acetate 10/1-3/1) to give 280.0mg of an oil. This oil was dissolved in 2mL of ethyl acetate hydrochloride (concentration about 2M) and stirred at 25 ℃ for 16 hours, whereupon a solid precipitated, which was filtered and dried to give 150.0mg of a white solid as the hydrochloride salt of the product in a yield of 57%.

¹H NMR(400MHz,D₂O)＝7.56(t,J＝8.0Hz,1H),7.42(d,J＝8.0Hz,1H),7.31(s,1H),7.19(d,J＝8.0Hz,1H),5.02-4.96(m,1H),3.86(d,J＝14.4Hz,1H),3.63(d,J＝14.0Hz,1H),3.23(t,J＝5.2Hz,2H),2.87(s,3H),2.46(dd,J＝6.0,14.8Hz,1H),1.91-1.76(m,4H),1.73-1.49(m,3H),1.36(d,J＝6.0Hz,6H),0.59(t,J＝7.2Hz,3H)；MS(ESI):320.2[M+1]⁺。

EXAMPLE 5 preparation of levomeptazinol prodrug molecule (Compound XW10195)

The compound XW10195 is levorotation meptazinol prodrug molecule: levo meptazinol cyclohexyl carbonate.

The method comprises the following steps:

3.6g (12.0mmol) of triphosgene were dissolved in 20mL of toluene to form a homogeneous solution. The solution was cooled to 0 ℃ and 1.2g (15.0mmol) pyridine was slowly added dropwise to form a yellow slurry. After stirring for 0.5 hour while keeping the reaction temperature at 0 ℃, a cyclohexanol solution (1.0g (10.0mmol) dissolved in 10mL of toluene) was added dropwise to the reaction. After the addition was complete, the reaction turned to a white slurry, which was stirred for 1 hour, then 30mL of water was added to the reaction to quench the reaction, which was extracted with dichloromethane (2X 30 mL). The combined organic phases were collected, dried, filtered and concentrated to give 1.1g of a pale yellow liquid (crude product) in 69% yield. The product was cyclohexyl chloroformate and was used in the next reaction without purification.

Step two:

0.2g (0.86mmol) of levomeptazinol and 173.5mg (1.7mmol) of triethylamine were dissolved in 2mL of dichloromethane to form a homogeneous solution. Cooled to 0 ℃ in an ice-water bath and 209.1mg (1.3mmol) of cyclohexyl chloroformate are added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 3 hours, and then diluted with 10mL of dichloromethane. The diluted reaction was washed with water (2 × 5 mL). The organic phase was collected, dried, filtered and concentrated to give an off-white oil, which was chromatographed on silica gel column (petroleum ether: ethyl acetate 10/1-3/1) to give 240.0mg of a viscous oil. This oil was dissolved in 2mL ethyl acetate hydrochloride (concentration about 2M) at 0 deg.C and stirred at 25 deg.C for 16 hours to give, after concentration, 200.0mg of a white solid as the hydrochloride salt of the product in 68% yield.

¹H NMR(400MHz,CDCl₃)＝7.30(t,J＝8.0Hz,1H),7.18(d,J＝8.0Hz,1H),7.12(s,1H),7.01(dd,J＝1.6,8.0Hz,1H),4.75-4.67(m,1H),2.84(d,J＝14.0Hz,1H),2.58-2.45(m,3H),2.38(s,3H),2.11(dd,J＝8.0,14.4Hz,1H),2.02-1.98(m,2H),1.82-1.49(m,9H),1.44-1.22(m,6H),0.59(t,J＝7.4Hz,3H)；MS(ESI):360.4[M+1]⁺。

EXAMPLE 6 preparation of levomeptazinol prodrug molecule (Compound XW10198)

The compound XW10198 is levorotatory meptazinol prodrug molecule: levo meptazinol benzyl carbonate.

0.2g (0.86mmol) of levomeptazinol and 104.1mg (1.0mmol) of triethylamine were dissolved in 4mL of dichloromethane to form a homogeneous solution. Cooled to 0 ℃ in an ice-water bath and 175.5mg (1.0mmol) of benzyl chloroformate are added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 3 hours, followed by concentration to give a semisolid, which was subjected to silica gel column chromatography (petroleum ether: ethyl acetate 10/1-1/1) to give 220.0mg of a pale yellow oil. The oil was dissolved in 2mL ethyl acetate hydrochloride (concentration about 2M) and stirred at 25 ℃ for 16 hours to give a foamy solid after concentration, 2mL methyl tert-butyl ether was added to the solid and slurried for 4 hours to form an off-white syrup, which was filtered and dried to give 190.0mg of off-white solid as the product hydrochloride in 55% yield.

¹H NMR(400MHz,D₂O)＝7.61-7.45(m,6H),7.42(d,J＝7.2Hz,1H),7.29(s,1H),7.19(d,J＝7.6Hz,1H),5.34(s,2H),3.84(d,J＝14.0Hz,1H),3.62(d,J＝14.0Hz,1H),3.22(t,J＝5.6Hz,2H),2.86(s,3H),2.45(d,J＝12.8Hz,1H),1.92-1.75(m,4H),1.65-1.57(m,3H),0.58(t,J＝7.0Hz,3H)；MS(ESI):368.8[M+1]⁺。

EXAMPLE 7 preparation of levomeptazinol prodrug molecule (Compound XW10199)

The compound XW10199 is levorotatory meptazinol prodrug molecule: levo meptazinol isobutyl carbonate.

0.2g (0.86mmol) of levomeptazinol and 104.1mg (1.0mmol) of triethylamine were dissolved in 4mL of dichloromethane to form a homogeneous solution. The solution was cooled to 0 ℃ with an ice-water bath and 128.8mg (0.9mmol) of isobutyl chloroformate were added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 3 hours, then 10mL of dichloromethane was added to dilute the reaction mixture, the diluted reaction mixture was washed with water (2 × 5mL), the organic phase was collected, dried, filtered and concentrated to obtain a white-like oil, and silica gel column chromatography (petroleum ether: ethyl acetate: 10/1-1/1) was performed to obtain 110.0mg of the oil. This oil was dissolved in 2mL of ethyl acetate hydrochloride (concentration about 2M), stirred at 25 ℃ for 16 hours, concentrated by an oil pump to give a foamy solid, to which 1mL of methyl t-butyl ether was added and slurried, filtered and dried to give 70.0mg of a white solid as the hydrochloride salt of the product in 22% yield.

¹H NMR(400MHz,D₂O)＝7.57(t,J＝7.8Hz,1H),7.43(d,J＝6.8Hz,1H),7.32(s,1H),7.21(d,J＝8.0Hz,1H),4.12(d,J＝6.4Hz,2H),3.92-3.80(m,1H),3.64(d,J＝14.0Hz,1H),3.24(br.s.,2H),2.90(s,3H),2.49(d,J＝12.0Hz,1H),2.08-2.01(m,1H),1.98-1.75(m,4H),1.67-1.60(m,3H),0.98(d,J＝6.8Hz,6H),0.61(t,J＝7.4Hz,3H)；MS(ESI):334.3[M+1]⁺。

Example 8 preparation of levomeptazinol prodrug molecule (Compound XW10200)

The compound XW10200 is a levomeptazinol prodrug molecule: l-meptazinol-4-oxatetrahydropyranyl carbonate.

The method comprises the following steps:

3.5g (11.8mmol) of triphosgene were dissolved in 20mL of toluene to form a homogeneous solution. The solution was cooled to 0 ℃ and 1.2g (15.0mmol) pyridine was slowly added dropwise to form a yellow slurry. After stirring for 0.5 hour while keeping the reaction temperature at 0 ℃, tetrahydropyran-4-ol solution (1.0g (9.8mmol) dissolved in 10mL of toluene) was added dropwise to the reaction. After the addition was complete, the reaction turned to a white slurry, which was stirred for 1 hour, then 30mL of water was added to the reaction to quench the reaction, which was extracted with ethyl acetate (2X 30 mL). The combined organic phases were collected, dried, filtered and concentrated to give 1.2g of a colourless liquid (crude product) in 75% yield. The product, 4-oxatetrahydropyranyl chloroformate, was not purified and was used directly in the next reaction.

Step two:

0.2g (0.86mmol) of levomeptazinol and 173.5mg (1.7mmol) of triethylamine were dissolved in 4mL of dichloromethane to form a homogeneous solution. The solution was cooled to 0 ℃ with an ice-water bath and 211.6mg (1.3mmol) of 4-oxatetrahydropyranyl chloroformate were added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 3 hours, then 10mL of dichloromethane was added to dilute the reaction mixture, the diluted reaction mixture was washed with water (2 × 5mL), the organic phase was collected, dried, filtered and concentrated to obtain a white-like oil, and silica gel column chromatography (petroleum ether: ethyl acetate: 10/1-3/1) was performed to obtain 180.0mg of a pale yellow oil. This oil was dissolved in 2mL of ethyl acetate hydrochloride (concentration about 2M) at 0 ℃ and stirred at 25 ℃ for 16 hours to give a foamy solid after concentration with an oil pump, and 2mL of methyl t-butyl ether was added to the solid and slurried for 4 hours, followed by filtration and drying to give 180.0mg of an off-white solid as the product hydrochloride in 53% yield.

¹H NMR(400MHz,D₂O)＝7.56(t,J＝8.0Hz,1H),7.42(d,J＝7.6Hz,1H),7.32(s,1H),7.21(d,J＝8.0Hz,1H),5.03-4.97(m,1H),4.01-3.81(m,3H),3.70-3.58(m,3H),3.27-3.16(m,2H),2.88(s,3H),2.48-2.41(m,1H),2.15-2.01(m,2H),2.00-1.73(m,6H),1.72-1.50(m,3H),0.58(t,J＝7.4Hz,3H)；MS(ESI):362.3[M+1]⁺。

EXAMPLE 9 preparation of levomeptazinol prodrug molecule (Compound XW10202)

The compound XW10202 is a levomeptazinol prodrug molecule: levomeptazinol- ((1R,2S,5R) -2-isopropyl-5-methyl) cyclohexyl carbonate.

The method comprises the following steps:

2.3g (7.7mmol) of triphosgene were dissolved in 20mL of toluene to form a homogeneous solution. The solution was cooled to 0 ℃ and 759.3g (9.6mmol) of pyridine were slowly added dropwise to form a yellow syrup. After stirring for 0.5 hour while keeping the reaction temperature at 0 ℃, an L-menthol solution (1.0g (6.4mmol) dissolved in 10mL of toluene) was added dropwise to the reaction. After the addition was complete, the reaction turned to a white slurry, which was stirred for 1 hour, then 30mL of water was added to the reaction to quench the reaction, which was extracted with ethyl acetate (2X 30 mL). The combined organic phases were collected, dried, filtered and concentrated to give 1.1g of a colourless liquid (crude product) in 84% yield. The crude product, L-menthyl chloroformate, was not purified and used directly in the next reaction.

Step two:

0.2g (0.86mmol) of levomeptazinol and 173.5mg (1.7mmol) of triethylamine were dissolved in 4mL of dichloromethane to form a homogeneous solution. The solution was cooled to 0 ℃ with an ice-water bath and 281.2mg (1.3mmol) of L-menthyl chloroformate were added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 3 hours, then 10mL of dichloromethane was added to dilute the reaction mixture, the diluted reaction mixture was washed with water (2 × 5mL), the organic phase was collected, dried, filtered and concentrated to obtain a white-like oil, and silica gel column chromatography (petroleum ether: ethyl acetate: 20/1-3/1) was performed to obtain 190.0mg of a colorless oil. This oil was dissolved in 2mL of ethyl acetate hydrochloride (concentration 2M) at 0 ℃ and stirred at 25 ℃ for 16 hours, and concentrated by an oil pump to give a foamy solid, to which 2mL of methyl t-butyl ether was added and slurried for 4 hours, followed by filtration and drying to give 190.0mg of a white solid as the hydrochloride salt of the product in a yield of 49%.

¹H NMR(400MHz,D₂O)＝7.54-7.45(m,1H),7.42-7.33(m,1H),7.15-7.02(m,2H),4.65-4.55(m,1H),3.77(br.s.,1H),3.57(d,J＝14.0Hz,1H),3.34-3.11(m,2H),2.90(s,3H),2.31(d,J＝10.0Hz,1H),2.12(d,J＝6.0Hz,1H),2.00-1.32(m,13H),1.15-1.01(m,2H),0.88(t,J＝6.2Hz,6H),0.78(d,J＝6.4Hz,3H),0.54(t,J＝7.0Hz,3H)；MS(ESI):416.4[M+1]⁺。

EXAMPLE 10 preparation of levomeptazinol prodrug molecule (Compound XW10208)

The compound XW10208 is a levomeptazinol prodrug molecule: levomeptazinol (4-methyl) benzyl carbonate.

The method comprises the following steps:

2.9g (9.8mmol) of triphosgene were dissolved in 20mL of toluene to form a homogeneous solution. The solution was cooled to 0 ℃ and 971.2g (12.3mmol) of pyridine were slowly added dropwise to form a yellow slurry. After stirring at 0 ℃ for 0.5 hour, a solution of 4-methylbenzyl alcohol (1.0g (6.4mmol) dissolved in 10mL of toluene) was added dropwise to the reaction. After the addition was complete, the reaction turned to a white slurry, which was stirred for 1 hour, then 30mL of water was added to the reaction to quench the reaction, which was extracted with ethyl acetate (2X 30 mL). The combined organic phases were collected, dried, filtered and concentrated to give 1.3g of a colourless liquid (crude product) in 87% yield. The crude 4-methylbenzyl chloroformate was used directly in the next reaction without purification.

Step two:

0.2g (0.86mmol) of levomeptazinol and 104.1mg (1.0mmol) of triethylamine were dissolved in 4mL of dichloromethane to form a homogeneous solution. The solution was cooled to 0 ℃ with an ice-water bath and 174.1mg (0.9mmol) of 4-methylbenzyl chloroformate were added dropwise. The reaction mixture was naturally warmed to 25 ℃ and stirred for 3 hours, then 10mL of dichloromethane was added to dilute the reaction mixture, the diluted reaction mixture was washed with water (2 × 5mL), the organic phase was collected, dried, filtered and concentrated to obtain a white-like oil, and silica gel column chromatography (petroleum ether: ethyl acetate: 20/1-1/1) was performed to obtain 150.0mg of a pale yellow oil. This oil was dissolved in 2mL of ethyl acetate hydrochloride (concentration about 2M) at 0 ℃ and stirred at 25 ℃ for 16 hours to give a viscous oil after concentration with an oil pump, and 2mL of methyl t-butyl ether was added to the solid and slurried for 4 hours, followed by filtration and drying to give 150.0mg of a white solid as the hydrochloride salt of the product in a yield of 42%.

¹H NMR(400MHz,D₂O)＝7.48(t,J＝7.2Hz,1H),7.42-7.28(m,3H),7.26-7.01(m,4H),5.21(s,2H),3.73(br.s.,1H),3.55(d,J＝14.0Hz,1H),3.30-3.10(m,2H),2.84(s,3H),2.41-2.31(m,1H),2.28(s,3H),1.95-1.76(m,3H),1.74-1.43(m,4H),0.51(t,J＝7.2Hz,3H)；MS(ESI):382.3[M+1]⁺。

EXAMPLE 11 preparation of levomeptazinol prodrug molecule (Compound XW10210)

The compound XW10210 is a levomeptazinol prodrug molecule: levo-meptazinol (N-methyl) -4-piperidinylcarbonate.

127.2mg (0.4mmol) of triphosgene are dissolved in 4mL of dichloromethane to form a homogeneous solution, which is cooled to 0 ℃ and a mixed solution of 148.1mg (1.3mmol) of N-methylpiperidin-4-ol and 130mg (1.3mmol) of triethylamine in 10mL of dichloromethane is added dropwise. The reaction temperature was maintained at 0 ℃ and after stirring for 0.5 hour, 0.2g (0.8mmol) of levomeptazinol solid was added to the reaction at one time and the temperature was naturally raised to 25 ℃ and stirred for 16 hours. The reaction mixture was diluted with 4mL of dichloromethane, and the diluted reaction mixture was washed with 10mL of saturated sodium bicarbonate solution. The organic phase was collected, dried, filtered and concentrated to give a yellow oil, which was subjected to silica gel column chromatography (petroleum ether: ethyl acetate 10/1-1/1, 0.5% triethylamine) to give a pale yellow oil. This oil was dissolved in 2mL ethyl acetate hydrochloride (concentration about 2M) at 0 ℃ to give a white syrup, which was filtered and dried to give 210.0mg of a white solid as the hydrochloride salt of the product in 55% yield.

¹H NMR(400MHz,D₂O)＝7.64-7.53(m,1H),7.45(d,J＝7.6Hz,1H),7.39-7.31(m,1H),7.27-7.17(m,1H),5.16(br.s.,1H),5.06-4.92(m,1H),3.88(d,J＝14.4Hz,1H),3.74-3.58(m,2H),3.53-3.46(m,1H),3.40-3.11(m,4H),3.02-2.86(m,5H),2.61-2.39(m,2H),2.31(d,J＝15.6Hz,1H),2.20-2.11(m,1H),2.10-1.75(m,5H),1.74-1.49(m,3H),0.60(t,J＝7.2Hz,3H)；MS(ESI):375.0[M+1]⁺。

EXAMPLE 12 preparation of levomeptazinol prodrug molecule (Compound XW10212)

The compound XW10212 is a levomeptazinol prodrug molecule: L-meptazinol-N-ethoxyacyl-L-valine ester.

The method comprises the following steps:

1.0g (8.5mmol) of L-valine and 3.1g (22.2mmol) of potassium carbonate were dissolved in 10mL of water, and after the solution was cooled to 0 ℃ 1.2g (11.1mmol) of ethyl chloroformate was added dropwise. The reaction was warmed to 25 ℃ and stirred for 16 h, then washed with ethyl acetate (2 × 20mL) and the aqueous phase was adjusted to pH 2 with cold concentrated hydrochloric acid in an ice bath. Ethyl acetate (2 × 30mL) was extracted. The organic phase was collected, dried, filtered and concentrated to give 1.5g (60%) of N-ethoxyacyl-L-valine as a colorless oil.

¹H NMR(400MHz,CDCl₃)＝5.12(d,J＝9.2Hz,1H),4.33(dd,J＝4.6,8.8Hz,1H),4.14(q,J＝7.2Hz,2H),2.32-2.11(m,1H),1.26(t,J＝7.2Hz,3H),1.01(d,J＝6.4Hz,3H),0.94(d,J＝7.2Hz,3H)。

Step two:

0.2g (0.86mmol) of levomeptazinol and 174.8mg (0.9mmol) of N-ethoxyacyl-L-valine are dissolved in 4mL of methylene chloride, and 212.2mg (1.0mmol) of DCC and 5mg of DMAP are added to the solution to form a white slurry, which is stirred at 25 ℃ for 16 hours and then filtered. The filtered reaction solution was diluted with 10mL dichloromethane, washed with saturated ammonium chloride solution (2 × 5mL), the organic phase was collected, dried, filtered and spun to give a pale yellow oil, which was isolated by acidic preparative separation to give 0.2g levomeptazinol-N-ethoxyacyl-L-valine ester hydrochloride as a white solid in 53% yield.

¹H NMR(400MHz,D₂O)＝7.55(t,J＝7.8Hz,1H),7.41(d,J＝8.0Hz,1H),7.17-7.06(m,2H),4.33(d,J＝5.2Hz,1H),4.12(q,J＝6.8Hz,2H),3.84(d,J＝16.0Hz,1H),3.61(d,J＝13.6Hz,1H),3.21(t,J＝6.0Hz,2H),2.85(s,3H),2.50-2.29(m,2H),1.98-1.49(m,7H),1.22(t,J＝7.0Hz,3H),1.05(dd,J＝7.0,10.4Hz,6H),0.56(t,J＝7.2Hz,3H)；MS(ESI):405.2[M+1]⁺。

EXAMPLE 13 preparation of levomeptazinol prodrug molecule (Compound XW10216)

The compound XW10216 is a levomeptazinol prodrug molecule: L-meptazinol-N-isopropoxyacyl-L-valine ester.

0.2g (0.86mmol) of levomeptazinol and 191.6mg (0.9mmol) of N-isopropoxyacyl-L-valine are dissolved in 4mL of dichloromethane, and 212.2mg (1.0mmol) of DCC and 5mg of DMAP are added to the solution to form a white slurry, which is stirred at 25 ℃ for 16 hours and then filtered. The filtered reaction solution was diluted with 10mL dichloromethane, washed with saturated ammonium chloride solution (2 × 5mL), the organic phase was collected, dried, filtered and spun to give a pale yellow oil, which was then isolated by acidic preparative separation to give 0.2g levomeptazinol-N-isopropoxyacyl-L-valine ester hydrochloride as a white solid in 51% yield.

¹H NMR(400MHz,D₂O)＝7.58(t,J＝8.0Hz,1H),7.44(d,J＝7.6Hz,1H),7.19-7.09(m,2H),4.94-4.84(m,1H),4.33(d,J＝5.6Hz,1H),3.87(d,J＝14.8Hz,1H),3.63(d,J＝14.0Hz,1H),3.32-3.15(m,2H),2.88(s,3H),2.47-2.25(m,2H),2.02-1.55(m,7H),1.37-1.17(m,6H),1.08(dd,J＝7.0,10.6Hz,6H),0.59(t,J＝7.2Hz,3H)；MS(ESI):419.3[M+1]⁺。

EXAMPLE 14 preparation of levomeptazinol prodrug molecule (Compound XW10243)

The compound XW10243 is a levomeptazinol prodrug molecule: levo-meptazinol-2-acetoxyisobutyrate.

0.3g (1.3mmol) of levomeptazinol and 156.1mg (1.5mmol) of triethylamine are dissolved in 4mL of dichloromethane to form a homogeneous solution, the reaction solution is cooled to 0 ℃, 232.8mg (1.4mmol) of 2-acetoxyisobutyryl chloride is added dropwise, after stirring for 16 hours, 10mL of dichloromethane is added to dilute the reaction solution, and the reaction solution is washed with brine (2X 8 mL). The organic phase was collected, dried, filtered and concentrated to obtain a semi-solid, which was purified by acidic preparation to obtain 70mg of levomeptazinol-2-acetoxyisobutyrate hydrochloride as a colorless oil with a yield of 14%.

¹H NMR(400MHz,D₂O)＝7.56(d,J＝8.0Hz,1H),7.42(d,J＝8.0Hz,1H),7.15-7.04(m,2H),3.85(d,J＝14.4Hz,1H),3.62(d,J＝14.0Hz,1H),3.22(t,J＝5.8Hz,2H),2.86(s,3H),2.44(dd,J＝5.6,14.8Hz,1H),2.16(s,3H),1.99-1.76(m,4H),1.70(s,6H),1.64-1.54(m,3H),0.57(t,J＝7.4Hz,3H)；MS(ESI):362.5[M+1]⁺。

EXAMPLE 15 preparation of levomeptazinol prodrug molecule (Compound XW10245)

The compound XW10245 is a levomeptazinol prodrug molecule: levo-meptazinol-N-acetylsarcosinate.

The method comprises the following steps:

0.2g (0.86mmol) of levomeptazinol and 178.4mg (0.9mmol) of N-Boc-sarcosine were dissolved in 4mL of dichloromethane, and 212.2mg (1.0mmol) of DCC and 5mg of DMAP were added to the solution to form a white syrup, which was stirred at 25 ℃ for 16 hours and then filtered. The filtered reaction solution was diluted with 10mL dichloromethane, washed with saturated ammonium chloride solution (2 × 5mL), the organic phase was collected, dried, filtered and spin-dried to give a pale yellow oil, which was isolated to give 250.0mg levomeptazinol-N-Boc-sarcosine ester in 72% yield.

¹H NMR(400MHz,CDCl₃)＝7.38-7.32(m,1H),7.19(t,J＝7.4Hz,1H),7.04(s,1H),6.98(t,J＝7.4Hz,1H),4.23(s,1H),4.13(s,1H),3.16(t,J＝14.0Hz,1H),3.02(d,J＝11.2Hz,3H),2.98-2.79(m,2H),2.59(d,J＝15.2Hz,3H),2.72-2.53(m,1H),2.33-2.18(m,1H),1.94-1.66(m,6H),1.64-1.54(m,1H),1.48(d,J＝5.6Hz,9H),0.60(dt,J＝2.6,7.0Hz,3H)。

Step two:

250.0mg (0.6mmol) of levomeptazinol-N-Boc-sarcosinate was dissolved in 4mL of dichloromethane, cooled to 0 ℃, 1mL of trifluoroacetic acid was added, and the reaction was naturally warmed to 25 ℃ and stirred for 2 hours. Dichloromethane and trifluoroacetic acid were removed by oil pump concentration to give a brown oil, and 4mL of dichloromethane and 187.6mg (1.8mmol) of triethylamine were added to form a brown solution. The solution was cooled to 0 ℃ and 58.2mg (0.7mmol) of acetyl chloride was added dropwise, and the reaction was allowed to proceed for 16 hours while warming to 25 ℃. After dilution with e.g. 10mL dichloromethane, washing with saturated brine (2 × 5mL), collecting the organic phase, drying, filtering, concentrating to give a white-like oil, and acidic isolation to give 90mg levomeptazinol-N-acetylsarcosinate hydrochloride as a pale yellow viscous oil with a yield of 38%.

¹H NMR(400MHz,CD₃OD)＝7.53(t,J＝8.0Hz,1H),7.37(d,J＝8.4Hz,1H),7.29(s,1H),7.18-7.09(m,1H),4.39(s,2H),3.95(d,J＝14.4Hz,1H),3.57(d,J＝14.4Hz,1H),3.22(s,3H),3.27-3.18(m,1H),3.04-2.90(m,3H),2.49-2.36(m,1H),2.23-2.08(m,3H),2.01-1.56(m,7H),1.31(t,J＝7.2Hz,1H),0.63(t,J＝7.2Hz,3H)；MS(ESI):347.0[M+1]⁺。

EXAMPLE 16 preparation of levomeptazinol prodrug molecule (Compound XW10260)

The compound XW10260 is a levomeptazinol prodrug molecule: levo-meptazinol-N-isobutyryl sarcosinate.

250.0mg (0.6mmol) of levomeptazinol-N-Boc-sarcosinate was dissolved in 4mL of dichloromethane, cooled to 0 ℃, 1mL of trifluoroacetic acid was added, and the reaction was naturally warmed to 25 ℃ and stirred for 2 hours. Dichloromethane and trifluoroacetic acid were removed by oil pump concentration to give a brown oil, and 4mL of dichloromethane and 187.6mg (1.9mmol) of triethylamine were added to form a brown solution. The solution was cooled to 0 ℃ and 74.2mg (0.7mmol) of isobutyryl chloride was added dropwise, and the reaction was allowed to proceed for 16 hours at 25 ℃. Diluting with 10mL dichloromethane, washing with brine (2X5mL), collecting the organic phase, drying, filtering, concentrating to obtain a white-like oil, separating by acidic preparation to obtain 120.0mg levomeptazinol-N-isobutyryl sarcosinate hydrochloride, yield 49%, white bubble solid.

¹H NMR(400MHz,CD₃OD)＝7.57-7.46(m,1H),7.42-7.21(m,2H),7.12(d,J＝8.0Hz,1H),4.36(s,2H),4.02-3.84(m,1H),3.58(d,J＝14.0Hz,1H),3.26(s,3H),3.30-3.17(m,1H),2.93(s,3H),3.16-2.74(m,2H),2.52-2.35(m,1H),2.06-1.52(m,7H),1.13(d,J＝6.4Hz,6H),0.63(t,J＝7.2Hz,3H)；MS(ESI):375.2[M+1]⁺。

EXAMPLE 17 preparation of levomeptazinol prodrug molecule (Compound XW10258)

The compound XW10258 is a levomeptazinol prodrug molecule: levo-meptazinol-N-isobutyryl-L-alanine ester.

The method comprises the following steps:

0.2g (0.8mmol) of levomeptazinol and 178.4mg (0.9mmol) of N-Boc-L-alanine were dissolved in 4mL of dichloromethane, and 212.2mg (1.0mmol) of DCC and 5mg of DMAP were added to the solution to form a white syrup, which was stirred at 25 ℃ for 16 hours and then filtered. The filtered reaction solution was diluted with 10mL dichloromethane, washed with saturated ammonium chloride solution (2 × 5mL), the organic phase was collected, dried, filtered, and spin-dried to give a pale yellow oil, which was isolated by neutral preparative separation to give 250.0mg levomeptazinol-N-Boc-L-alanine ester with a yield of 72% as a pale yellow oil.

¹H NMR(400MHz,CD₃OD)＝7.54(t,J＝8.0Hz,1H),7.37(d,J＝8.0Hz,1H),7.25(s,1H),7.11(d,J＝8.0Hz,1H),4.34(q,J＝7.2Hz,1H),3.94(d,J＝14.4Hz,1H),3.58(d,J＝14.4Hz,1H),3.24(t,J＝6.2Hz,2H),2.93(s,3H),2.45-2.40(m,1H),2.08-1.66(m,6H),1.62-1.57(m,1H),1.52(d,J＝7.2Hz,3H),1.46(s,9H),0.63(t,J＝7.4Hz,3H)；MS(ESI):405.2[M+1]⁺。

Step two:

250.0mg (0.6mmol) of levomeptazinol-N-Boc-L-alanine ester was dissolved in 4mL of dichloromethane, cooled to 0 ℃ and 1mL of trifluoroacetic acid was added, and the reaction was naturally warmed to 25 ℃ and stirred for 2 hours. Dichloromethane and trifluoroacetic acid were removed by oil pump concentration to give a brown oil, and 4mL of dichloromethane and 187.6mg (1.9mmol) of triethylamine were added to form a brown solution. The solution was cooled to 0 ℃ and 74.2mg (0.7mmol) of isobutyryl chloride was added dropwise, and the reaction was allowed to proceed for 16 hours at 25 ℃. Diluting with 10mL dichloromethane, washing with brine (2X5mL), collecting organic phase, drying, filtering, concentrating to obtain white oil, separating by acidic preparation to obtain 120.0mg levomeptazinol-N-isobutyryl-L-alanine ester hydrochloride, yield 47%, white bubble solid.

¹H NMR(400MHz,CD₃OD)＝7.55-7.45(m,1H),7.41-7.31(m,1H),7.23(s,1H),7.09(d,J＝6.4Hz,1H),4.51(q,J＝7.2Hz,1H),3.95(d,J＝12.0Hz,1H),3.57(d,J＝13.6Hz,1H),3.27-3.17(m,2H),2.93(s,3H),2.58-2.51(m,1H),2.47-2.38(m,1H),2.00-1.60(m,7H),1.56(d,J＝7.6Hz,3H),1.14(dd,J＝2.8,6.8Hz,6H),0.63(t,J＝7.2Hz,3H)；MS(ESI):375.1[M+1]⁺。

EXAMPLE 18 preparation of levomeptazinol prodrug molecule (Compound XW10271)

The compound XW10271 is a levomeptazinol prodrug molecule: (N- (S) -meptazinol oxoacyl) -L-alanyl-L-proline.

The method comprises the following steps:

2.0g (9.3mmol) N-Boc-L-proline, 2.0g (18.6mmol) benzyl alcohol, 3.6g (18.6mmol) EDCI and 113.5mg (0.9mmol) DMAP were dissolved in 40mL dichloromethane to form a slurry. To the slurry was added dropwise 4.8g (37.2mmol) of N, N-diisopropylethylamine. After completion of the dropwise addition, the reaction was carried out at 25 ℃ for 16 hours, diluted with 40mL of dichloromethane, and washed successively with cold 1M dilute hydrochloric acid (2X 80mL), water (100mL) and brine (2X 50 mL). The organic phase was dried, filtered and concentrated to give an oil which was separated on a column (petroleum ether/ethyl acetate. RTM. 10/1-1/1) to give 1.3g N-Boc-L-proline benzyl ester in 46% yield as a colorless oil.

¹H NMR(400MHz,CDCl₃)＝7.43-7.28(m,5H),5.31-5.03(m,2H),4.38(dd,J＝3.2,8.6Hz,0.4H),4.26(dd,J＝3.8,8.6Hz,0.6H),3.64-3.31(m,2H),2.29-2.11(m,1H),2.05-1.79(m,3H),1.46(s,3H),1.34(s,6H)。

Step two:

1.3g (4.3mmol) of benzyl N-Boc-L-proline was dissolved in 20mL of dichloromethane to form a clear solution, and 2mL of trifluoroacetic acid was added to the solution. After 3 hours at 25 ℃ reaction, concentrate to remove dichloromethane and trifluoroacetic acid to give crude 1.5g L-proline benzyl ester trifluoroacetate as a pale yellow oil which was used directly in the next reaction.

Step three:

0.8g (4.2mmol) of N-Boc-L-alanine, 1.5g (4.7mmol) of crude L-proline benzyl ester trifluoroacetate and 1.9g (5.1mmol) of HATU were dissolved in 40mL of dichloromethane to form a slurry, and 1.3g (10.5mmol) of N, N-diisopropylethylamine was added dropwise to the slurry. After completion of the dropwise addition, the reaction was carried out at 25 ℃ for 16 hours, diluted with 20mL of dichloromethane, and washed successively with cold 1M dilute hydrochloric acid (2X 50mL), water (50mL) and brine (2X 30 mL). The organic phase was dried, filtered and concentrated to give an oil which was separated on a column (petroleum ether/ethyl acetate. RTM. 10/1-1/1) to give 1.3g (82%) of benzyl N-Boc-L-alanyl-L-proline as a colorless oil.

¹H NMR(400MHz,CDCl₃)＝7.43-7.28(m,5H),5.20(d,J＝12.4Hz,1H),5.10(d,J＝12.4Hz,1H),4.65-4.55(m,1H),4.52-4.38(m,1H),3.77-3.65(m,1H),3.65-3.53(m,1H),2.27-2.15(m,1H),2.06-1.94(m,3H),1.42(s,9H),1.29(d,J＝6.8Hz,3H)。

Step four:

445.0mg (1.2mmol) of N-Boc-L-alanyl-L-proline benzyl ester was dissolved in 4mL of dichloromethane to form a clear solution, and 1mL of trifluoroacetic acid was added to the solution. After 3 hours at 25 ℃ reaction, concentrate to remove dichloromethane and trifluoroacetic acid to give crude 0.5g L-alanyl-L-proline benzyl ester trifluoroacetate as a pale yellow oil which was used directly in the next reaction.

Step five:

250.0mg (1.1mmol) of levomeptazinol was dispersed in 4mL of dichloromethane to form a slurry, and 191.2mg (1.2mmol) of CDI was added to the slurry. The reaction was heated to reflux for 48 h to form a homogeneous clear solution, 0.5g (1.2mmol) of crude L-alanyl-L-proline benzyl ester trifluoroacetate was added to the reaction to form a slurry, which was diluted with 6mL of dichloromethane after 16 h reaction at 25 ℃ and washed sequentially with saturated brine (2X5mL) and water (5 mL). The organic phase was collected, dried and concentrated to give a semi-solid material which was isolated by preparative isolation to give 220.0mg (38%) of benzyl (N- (S) -meptazinol oxoacyl) -L-alanyl-L-proline as a white solid.

¹H NMR(400MHz,CD₃OD)＝7.49(t,J＝8.0Hz,1H),7.44-7.27(m,6H),7.26-7.16(m,1H),7.14-7.04(m,1H),5.20-5.12(m,2H),4.58-4.40(m,2H),3.92(d,J＝14.4Hz,1H),3.83-3.73(m,1H),3.71-3.54(m,2H),3.24(t,J＝6.0Hz,2H),2.91(s,3H),2.50-2.39(m,1H),2.30-2.22(m,1H),2.11-1.78(m,7H),1.76-1.50(m,3H),1.35(d,J＝7.2Hz,3H),0.62(t,J＝7.4Hz,3H)。

Step six:

220.0mg (0.4mmol) of benzyl (N- (S) -meptazinol oxoacyl) -L-alanyl-L-proline is dissolved in 4mL of methanol to form a homogeneous solution, and 20.0mg of palladium on charcoal is added to form a black slurry. Hydrogenation reaction at 25 deg.C for 2 hr, filtering, concentrating, neutral preparing and separating to obtain 90.0mg (N- (S) -meptazinol oxoacyl) -L-alanyl-L-proline, yield 49%, as white powder solid.

¹H NMR(600MHz,CD₃OD)＝7.50(t,J＝8.1Hz,1H),7.34(d,J＝8.4Hz,1H),7.24(s,1H),7.10(dd,J＝1.6,8.1Hz,1H),4.51(q,J＝7.2Hz,1H),4.46(dd,J＝4.3,8.7Hz,1H),3.93(d,J＝13.8Hz,1H),3.83-3.75(m,1H),3.72-3.56(m,2H),3.25(t,J＝6.0Hz,2H),2.92(s,3H),2.44(dd,J＝6.0,14.4Hz,1H),2.30-2.21(m,1H),2.12-1.81(m,7H),1.76-1.67(m,1H),1.67-1.52(m,2H),1.43(d,J＝6.6Hz,3H),0.62(t,J＝7.2Hz,3H)；MS(ESI):446.3[M+1]⁺。

EXAMPLE 19 preparation of levomeptazinol prodrug molecule (Compound XW10275)

The compound XW10275 is a levomeptazinol prodrug molecule: levomeptazinol-1, 1' -dihydroxyisobutyrate.

The method comprises the following steps:

0.2g (0.8mmol) of levomeptazinol and 164.8mg (1.0mmol) of 5-formyl-2, 2-dimethyl-1, 3-dioxane were dissolved in 4mL of dichloromethane, 212.2mg (1.0mmol) of DCC and 5mg of DMAP were added to the solution to form a white slurry, and the mixture was stirred at 25 ℃ for 16 hours and then filtered. The filtered reaction solution was diluted with 10mL of dichloromethane, washed with saturated ammonium chloride solution (2 × 5mL), the organic phase was collected, dried, filtered and spin-dried to give a pale yellow oil, which was isolated to give 150.0mg of(s) -meptazinol-2, 2-dimethyl-1, 3-dioxane-5-carboxylate, yield 47% as a white solid.

¹H NMR(400MHz,CDCl₃)＝7.31(d,J＝8.0,1H),7.19(d,J＝7.6Hz,1H),7.00(s,1H),6.90(dd,J＝1.2,8.0Hz,1H),4.26-4.16(m,4H),3.09-3.02(m,1H),2.85(d,J＝14.0Hz,1H),2.60-2.45(m,3H),2.39(s,3H),2.10(dd,J＝8.0,14.4Hz,1H),1.77-1.59(m,6H),1.58-1.37(m,1H),1.49(s,3H),1.46(s,3H),0.59(t,J＝7.6Hz,3H)。

Step two:

30.0mg (0.08mmol) of levomeptazinol-2, 2-dimethyl-1, 3-dioxane-5-carboxylate was dissolved in 1mL of acetonitrile and 1mL of water, concentrated hydrochloric acid was added to adjust pH to 1, after reaction at 25 ℃ for 1.5 hours, sodium bicarbonate was added to adjust pH to 6-7, the acetonitrile was removed by concentration, and the remaining aqueous solution was prepared and isolated under neutral conditions to give 10.0mg of levomeptazinol-1, 1' -dihydroxyisobutyrate in a yield of 35% as a colorless viscous gum.

¹H NMR(400MHz,CD₃OD)＝7.52(t,J＝8.0Hz,1H),7.36(d,J＝7.6Hz,1H),7.28(s,1H),7.13(d,J＝7.6Hz,1H),4.00-3.88(m,4H),3.74-3.45(m,2H),3.25(t,J＝5.8Hz,2H),3.07-2.99(m,1H),2.93(s,3H),2.43(dd,J＝6.0,14.4Hz,1H),2.06-1.81(m,4H),1.81-1.70(m,1H),1.69-1.48(m,2H),0.63(t,J＝7.4Hz,3H)；MS(ESI):336.0。

EXAMPLE 20 prodrug molecule in vitro chemical stability test

1. Testing the chemical stability of prodrug molecules in buffer

Buffers with pH of 1.2, 6.5, 7.4 and 8.0 were prepared as follows:

pH 1.2 buffer: taking 765 mu L concentrated hydrochloric acid, and adding water to dilute to 100mL to obtain the final product; pH 6.5 phosphate buffer: taking 6.8g of monopotassium phosphate, adding 15.2mL of 1mol/L sodium hydroxide solution, and diluting to 1L with water to obtain the potassium phosphate; pH 7.4 phosphate buffer: taking 6.8g of monopotassium phosphate, adding 39.5mL of 1mol/L sodium hydroxide solution, and diluting to 1L with water to obtain the potassium phosphate; pH 8.0 phosphate buffer: 2.722g of monopotassium phosphate is dissolved in water and diluted to 100mL to obtain a solution A; dissolving 0.8g of sodium hydroxide in water, and diluting to 100mL to obtain a solution B; mixing the 25mL solution A and 23.05mL solution B, and diluting with water to 100 mL.

The experiment was carried out as follows:

the buffer was preheated at 37 ℃ for 3 minutes. To 1.0mL of the buffer, 0.1mL of a reaction solution (each of the indicated compounds obtained by the preparation in examples) of 0.1mg/mL was added. And incubating the sample at 37 ℃, sampling and analyzing at the time points of 0 minute, 30 minutes, 1 hour, 2 hours and 4 hours of reaction respectively, and detecting the residual content of the original form of the compound by using LC-MS. All were analyzed in parallel.

The results are shown in Table 1. From the results shown in table 1, it is clear that the compounds shown exhibit better stability when incubated for 2-4 hours in buffers at pH 1.2, 6.5, 7.4 and 8.0.

2. Testing the stability of prodrug molecules in simulated gastric fluid

Preparing artificial gastric juice: 0.04g of sodium chloride and 0.06g of pepsin were dissolved in 0.14mL of concentrated hydrochloric acid, and diluted to 20mL with water. The pH was determined to be 1.20. + -. 0.05.

The experiment was carried out as follows: mu.L of working solution (stock solution in DMSO, diluted with 50% acetonitrile/water) was pipetted from 200. mu.M in 96-well plates, one plate at each time point (T0, 1h, 2 h, 3 h, 24 h) and two replicates (duplicate wells) were made each time. In addition to the T0 point, after adding 4. mu.L of the test drug working solution to the deep-well plate at other time points, 396. mu.L of the artificial gastric juice was added to give a final concentration of 2. mu.M for incubation, and the concentrations of the organic phase DMSO and acetonitrile were 0.2% and 0.45%. The samples were incubated at 300 rpm in an incubator at 37 ℃ for the corresponding time. The test drugs were mixed by adding 800. mu.L of glacial acetonitrile containing 200ng/mL tolbutamide and labetalol (internal standard) immediately after the corresponding incubation time (T0, 1 hour, 2 hours, 3 hours, 24 hours) was completed. From each well, 100. mu.L of the liquid was taken out and added to a 96-well plate, and 200. mu.L of acetonitrile containing 200ng/mL of tolbutamide and labetalol (internal standard) was added again and mixed well.

Point T0 preparation: after 4 mul of tested medicine working solution is added into the deep hole plate, 800 mul of acetonitrile containing 200ng/mL of tolbutamide and labetalol (internal standard) is added to terminate the reaction, 396 mul of artificial gastric juice is added to be mixed uniformly, 100 mul of liquid is taken out from the deep hole plate, 200 mul of acetonitrile containing 200ng/mL of tolbutamide and labetalol (internal standard) is added to be mixed uniformly.

The 96 deep well plate was placed in a 4 ℃ centrifuge and centrifuged at 4000rpm for 20 minutes. After centrifugation, 60. mu.L of the supernatant was added to 180. mu.L of water and mixed well, and then sample analysis was performed by LC/MS/MS.

The results are shown in Table 1. From the above results, it can be seen that the compounds show better stability after incubation in artificial gastric juice for 24 hours.

Table 1 shows the partial results of the stability in buffer, artificial gastric fluid, of levomeptazinol prodrug molecules prepared in the previous examples.

TABLE 1

EXAMPLE 21 Metabolic stability determination of test Compounds

1. Rat/human liver S9 component metabolic stability assay

The release potency of the levomeptazinol prodrug molecule of the invention prepared in the previous example for the conversion of the pro-drug to levomeptazinol in vitro was determined using the rat/human liver S9 component metabolic stability assay protocol.

The experiment was carried out as follows:

to 360. mu.L of Tris buffer (pH 7.4) was added 40. mu.L of 500. mu.M of the assay solution (each of the compounds prepared in examples) to give a final concentration of 50. mu.M. mu.L of the above reaction solution was taken in portions, 100. mu.L of S9 solution (protein content: 1mg/mL) was added thereto, the mixture was preheated in a water bath at 37 ℃ for 10min, and 80. mu.L of 1.3mM NADP was added thereto to initiate the reaction. 600 mul of glacial acetonitrile stop solution (containing 200ng/mL each of the internal standard substances of tolbutamide, labetalol, propranolol and choline) and medium vortex mixing are respectively added into each sample at the time points of 0, 5, 10, 20, 30 and 60min to stop the reaction, the mixture is centrifuged at 4 ℃ and 4000rpm for 20 min, and the supernatant is taken for injection. Each sample is divided into two parts in parallel, and the residual content of the original form of the compound and the generation content of the parent drug are detected by an LC-MS/MS method.

The results show (see table 2): an in vitro levomeptazinol release potency assay using rat/human liver S9 fraction showed that the prodrug compound was able to be metabolized efficiently. Wherein the production rate of the mother drug of the rat S9 is lower, and the correlation that the levo-meptazinol can be continuously metabolized by the rat S9. In the metabolism experiment of the S9 component of human liver, the prodrug is rapidly metabolized and the levomeptazinol is effectively released.

2. Rat/human whole blood metabolic stability test

A rat/human whole blood metabolic stability assay protocol was used to determine the release potency of the compounds of the present application for in vitro conversion from prodrug to parent drug.

The experiment was carried out as follows:

mu.L of 250. mu.M working solution of the test compound was spiked into 98. mu.L of whole blood to give a final concentration of 5. mu.M. The reaction samples were incubated at about 60 rpm in a 37 ℃ water bath. At 0, 10, 30, 60 and 120 minutes, 100. mu.L each of the reaction samples were removed and the reaction was terminated by adding 100. mu.L of ultrapure water and 600. mu.L of glacial acetonitrile (containing the internal reference 200ng/mL tolbutamide, 20ng/mL labetalol). All samples were vortexed for 10 minutes, followed by centrifugation at 4000rpm for 10 minutes to precipitate proteins. Transfer 100 μ L of supernatant to a new plate. The supernatant was diluted with 200. mu.L of ultrapure water and then shaken at 800 rpm for 10 minutes. The samples were analyzed using LC/MS to detect the remaining amount of test compound and the efficiency of levomeptazinol production.

The results show (see table 2): in vitro levomeptazinol release potency assay using rat/human whole blood showed that the prodrug compound was able to be converted to the parent drug with multiple release efficiencies, indicating that after administration of the prodrug compound to rat/human, it could be converted to levomeptazinol in the systemic circulation.

Wherein the in vitro enzyme metabolic stability results for some of the compounds are shown in table 2:

TABLE 2

Example 22 evaluation of the pharmacodynamic Effect of levomeptazinol on Spinal Nerve Ligation (SNL) SD rat model

The SNL model is a common animal model for neuropathic pain assessment. The purpose of this experiment was to evaluate the utility of levomeptazinol to reduce mechanical allodynia in SNL rats.

Experimental groups:

the test steps are as follows:

building an SNL model:

1) the medicines in each group are correspondingly configured by taking physiological saline as a solvent according to different administration requirements.

2) Before operation, all the related vessels are sterilized and sterilized.

3) All animals were anesthetized with pentobarbital (50mg/kg, i.p.). Prior to surgical incision, the animal's toes were compressed to confirm that the animal had been completely anesthetized prior to surgery. Applying eye ointment on animal eyes to prevent cornea drying.

4) The hair of the lower body of the animal was shaved and the skin of the operation area was disinfected three times with iodophor and 70% ethanol. The operation is started after the skin is dry.

5) A longitudinal incision was made in the back of the sacrum at the waist of the animal using a scalpel, exposing the left paraspinal muscles, and the musculature was separated using a spreader to expose the vertebra.

6) The left L5 and L6 spinal nerves were separated and tightly ligated with 6-0 silk thread. The wound is closed while the skin is sutured closed.

7) After surgery, the animals were placed on an electric blanket and 5mL of saline was injected subcutaneously to prevent dehydration. The animals were returned to their cages after they fully recovered (freely movable).

1. Mechanical allodynia test

1) The rat is placed in the organic glass box alone, and the box bottom is the net in order to guarantee that rat foot can test. Rats will be acclimated for 15 minutes prior to testing.

2) After acclimation was completed, the test fibers were used for testing in the middle hind paw of rats. The test fiber included 8 test strengths: 3.61(0.4g), 3.84(0.6g), 4.08(1g), 4.31(2g), 4.56(4g), 4.74(6g), 4.93(8g), 5.18(15 g). For testing, the test fiber was pressed vertically against the skin and force was applied to bend the fiber for 6-8 seconds, 5 seconds apart for each test. When tested, the animals quickly contracted their feet and were scored as a painful response. The animal's paw withdrawal when the test fiber left the animal's skin was also scored as a painful response. If the animal moves or ambulates, the pain response is not recorded and the test should be repeated.

3) When in test, 4.31(2g) is used firstly, if the animal has pain reaction, the test fiber with the lower force is used in the next test; if the animal did not respond to pain, the next test used the test fiber, which was the first most aggressive (Chaplan et al, J Neurosci Methods 53:55-63,1994). The maximum force of the test fiber was 5.18(15 g).

The test results are recorded in the tables shown in FIGS. 1-2, with pain response record x and no pain response record o. Among them, as shown in fig. 1-2, mechanical allodynia threshold value <4g was exhibited, and mechanical allodynia was not exhibited at 15 g.

Wherein the mechanical hyperalgesia is calculated using the following formula:

50% reaction threshold (g) ═ 10^(Xf+k))/10,000，

Where Xf is the final test fiber value used in the test, k is the table value, and is the average difference.

2. Baseline test for adaptation to animal and mechanical allodynia

Animals were acclimated for 15 minutes in the experimental environment 10 days after surgery and for three consecutive days in the test environment. One day prior to dosing (13 days after surgery), a baseline test for mechanical allodynia was performed and animals that did not exhibit mechanical allodynia (with a paw withdrawal threshold greater than 5) were randomized into post-culling cohorts.

Administration of drugs: dosing was according to the schedule of the experiment.

According to data analysis, the test conclusion of the SNL model is as follows: at various doses of 5mg/kg, 10 mg/kg and 20 mg/kg, the SNL-induced reversal of mechanical allodynia was achieved after administration of levomeptazinol both at 0.5 and 1 hour.

The results of comparison of the anti-allodynia effect of levomeptazinol at different doses and at different time points are shown in figure 3.

As shown in figure 3, p <0.05, p <0.001 is the compound compared to the solvent group; # p <0.05, # p <0.01 is a comparison of compound with levomeptazinol (5mg/kg 0.5 h); ^ p <0.05, ^ p <0.01 are compounds compared to levomeptazinol (5mg/kg 1h), all using one-way analysis of variance plus Dunnett multiple comparison test; % indicates the inhibition of mechanical allodynia in each group.

Wherein, the inhibition rate of mechanical allodynia is (mean value of solvent group-value of administration group)/(mean value of solvent group-15) × 100%.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A compound of formula I or a tautomer or a pharmaceutically acceptable salt of the compound of formula I,

wherein R is

2. Use of a compound as claimed in claim 1 for the manufacture of a medicament for the treatment of neurodegenerative diseases or acute and chronic pain.

3. Use according to claim 2, wherein the acute or chronic pain comprises traumatic, post-operative, obstetric and cancer pain, migraine or neuropathic pain.

4. Use according to claim 2, characterized in that said neurodegenerative diseases comprise alzheimer's disease and parkinson's disease.