Preparation method of locked nucleic acid intermediate

Abstract

The invention provides a preparation method of a locked nucleic acid intermediate compound as shown in a formula I. The preparation method comprises the following steps: reacting a compound as shown in a formula II in a solvent in the presence of a sulfonylation reagent and a corresponding acid to prepare the compound as shown in the formula I, the synthetic route of the compound is as follows: # imgabs0 #; wherein R1 is defined in the specification. The preparation method of the compound as shown in the formula I is simple in process route, improves selectivity and product yield, and has a relatively wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical synthesis, and particularly relates to a method for preparing a locked nucleic acid intermediate. Technical Background

[0002] Nucleic acid drugs are a new type of therapeutic agent designed based on nucleic acid molecules (DNA or RNA), which intervene in the disease process by precisely regulating gene expression or directly repairing genetic defects. These drugs mainly include antisense oligonucleotides (ASO), small interfering RNA (siRNA), messenger RNA (mRNA), and gene editing tools (such as the CRISPR-Cas9 system), and their mechanisms of action cover multiple pathways such as gene silencing, targeted protein expression regulation, and genome modification. Compared with traditional small molecule drugs, nucleic acid drugs have high specificity and can precisely intervene in the mRNA or non-coding RNA of pathogenic genes, showing breakthrough potential in the treatment of rare genetic diseases, tumors, viral infections, and metabolic diseases.

[0003] In recent years, with the rapid development of the nucleic acid drug field, the research and development direction of nucleic acid drugs has also shifted from orphan drugs to broad-spectrum drugs at the beginning, and the demand for nucleic acid molecules with high affinity, high specificity, and excellent biological stability is also increasing continuously; this means that the demand for the production of nucleic acid drugs will start to show explosive growth.

[0004] Locked nucleic acid (LNA), as a new type of nucleic acid modification molecule, has become a research and application hotspot due to its unique structural advantages and excellent biological properties; locked nucleic acid is mainly prepared by chemical means; (3aR,5S,6S,6aR)-6-(benzyloxy)-5-((benzyloxy)methyl)-2,2-dimethyl-5-((R)-oxan-2-yl)tetrahydrofuro[2,3-d][1,3]dioxol-4-one, as an important intermediate for preparing locked nucleic acid, usually adopts the route provided in (Modular Synthesis of Constrained Ethyl (cEt) Purine and Pyrimidine Nucleosides Helen Blade, Derek Bradley, Louis Diorazio, Timothy Evans, Barry R. Hayter, and Gareth P. Howell The Journal of Organic Chemistry 2015 80 (10), 5337-5343), which is specifically as follows:

[0005]

[0006] In the key step of the first step of this route, the deprotection selectivity is poor, and the by-products with both protecting groups removed account for a relatively large proportion. To control the selective deprotection, it will also cause incomplete reaction of the raw materials, and it is difficult to separate the by-products from the product, and the post-treatment is very difficult. In addition, the reaction conditions of the second step are also very harsh. The above reasons lead to great difficulty in the operation of the above synthesis route, low yield of the reaction product, and high synthesis cost. Summary of the Invention

[0007] The object of the present invention is to overcome the deficiencies in the current technology and provide a method for preparing locked nucleic acid intermediates that can simplify the process flow, reduce the reaction cost, take into account environmental protection and process stability on the premise of ensuring high yield and high purity, so as to promote the application of LNA in a wider range of biological and medical fields.

[0008] Specifically, the technical solution provided by the present invention is as follows:

[0009] A method for preparing a compound of formula I, which comprises the following steps: reacting a compound of formula II in the presence of a sulfonylation reagent and its corresponding acid in a solvent to obtain a compound of formula I;

[0010] The synthetic route is as follows:

[0011] ;

[0012] Wherein, R1 is selected from one of benzyl (Bn), tert-butyldiphenylsilyl (TBDPS), tert-butyldimethylsilyl (TBS), trimethylsilyl (TMS), naphthylmethyl, trityl (Tr), p-methoxytrityl (MMT), dimethoxytrityl (DMT) or tetrahydropyranyl (THP);

[0013] The solvent in the above preparation method is selected from one or more of tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), dimethyl sulfoxide (DMSO), dichloromethane (DCM), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetonitrile (MeCN), 1,2-dichloroethane (DCE), chloroform, methyl tert-butyl ether and diethyl ether (Et2O);

[0014] In the above preparation method, the sulfonylation reagent is selected from one of methanesulfonyl chloride (MsCl) and p-toluenesulfonyl chloride (TsCl); when the sulfonylation reagent is selected from methanesulfonyl chloride (MsCl), the corresponding acid is MsOH (methanesulfonic acid); when the sulfonylation reagent is selected from p-toluenesulfonyl chloride (TsCl), the corresponding acid is p-toluenesulfonic acid (TsOH).

[0015] Advantages of the present invention:

[0016] 1. The preparation method of the present invention has simple process conditions, high selectivity, high yield of the target product, and low product manufacturing cost, which is more conducive to large-scale production. Specific Embodiments

[0017] The following further describes in detail the specific embodiments of the present invention in conjunction with the examples. To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise clearly stated, throughout the specification and claims, the term "comprising" or its variations such as "comprises" or "including" etc. will be understood to include the stated components or steps, without excluding other components or steps.

[0018] In addition, to better illustrate the present invention, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present invention can also be implemented without some specific details. In some embodiments, the raw materials, methods, means, etc. well-known to those skilled in the art are not described in detail to highlight the gist of the present invention.

[0019] Specifically, the present invention first provides a preparation method of a compound of formula I, which includes the following steps: reacting a compound of formula II in the presence of a sulfonylation reagent and its corresponding acid in a solvent to obtain a compound of formula I;

[0020] The synthetic route is as follows:

[0021] ;

[0022] Wherein, R1 is selected from one of benzyl (Bn), tert-butyldiphenylsilyl (TBDPS), tert-butyldimethylsilyl (TBS), trimethylsilyl (TMS), trityl (Tr), p-methoxytriphenylmethyl (MMT), dimethoxytriphenylmethyl (DMT), naphthylmethyl or tetrahydropyranyl (THP);

[0023] The solvent in the above preparation method is selected from one or more of tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), dimethyl sulfoxide (DMSO), dichloromethane (DCM), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetonitrile (MeCN), 1,2-dichloroethane (DCE), chloroform, methyl tert-butyl ether and diethyl ether (Et2O);

[0024] In the above preparation method, the sulfonylation reagent is selected from one of methanesulfonyl chloride (MsCl) and p-toluenesulfonyl chloride (TsCl); when the sulfonylation reagent is selected from methanesulfonyl chloride (MsCl), the corresponding acid is MsOH (methanesulfonic acid); when the sulfonylation reagent is selected from p-toluenesulfonyl chloride (TsCl), the corresponding acid is p-toluenesulfonic acid (TsOH); it has been found that in the presence of the sulfonylation reagent and the corresponding acid, the product has high selectivity, high yield, and mild reaction conditions.

[0025] Preferably, in some technical solutions, the reaction solvent is selected from one of tetrahydrofuran (THF) and 2-methyltetrahydrofuran (2-MeTHF), and the sulfonylation reagent and its corresponding acid are TsCl and TsOH.

[0026] Preferably, in some technical solutions, the volume-mass ratio of the reaction solvent to Compound II is (3 - 6):1, the molar ratio of the sulfonylation reagent to Compound II is (1.1 - 1.2):1, and the molar ratio of the acid corresponding to the sulfonylation reagent to Compound II is (1.3 - 1.5):1;

[0027] Preferably, in the above preparation method, first add the sulfonylation reagent and its corresponding acid to the reaction solvent, lower the temperature of the reaction system, and control the temperature to be less than or equal to 0 °C; then add Compound II, and control the reaction temperature at room temperature after adding Compound II.

[0028] For the experimental methods without specific conditions in the following examples, preferentially refer to the guidance given in the present invention, and it is also possible to follow the experimental manuals or conventional conditions in the art, or refer to other experimental methods known in the art, or follow the conditions recommended by the manufacturer. In the following specific examples, for the measurement parameters of the raw material components, if there is no special description, there may be slight deviations within the weighing accuracy range. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed. The experimental methods used in the following examples are all conventional methods unless otherwise specified. The reagents, materials, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0029] Example 1: Synthesis of Compound 1

[0030]

[0031] Dissolve 73.6 g of TsOH and 65 g of TsCl in 500 ml of THF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 143.6 g of compound A. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract three times with EA, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 105.2 g of product compound 1, with a yield of 83.6%;

[0032] Example 2: Synthesis of compound 2

[0033]

[0034] Dissolve 33 g of TsOH and 28 g of TsCl in 350 mL of 2-MeTHF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 100 g of compound B. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract three times with EA, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 80.2 g of compound 2, with a yield of 87%.

[0035] Example 3: Synthesis of compound 3

[0036]

[0037] Dissolve 45 g of TsOH and 40 g of TsCl in 400 mL of THF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 100 g of compound C. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract three times with EA, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 74 g of compound 3, with a yield of 82.6%.

[0038] Example 4: Synthesis of compound 4

[0039]

[0040] Dissolve 70 g of TsOH and 63.5 g of TsCl in 500 mL of THF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 150 g of compound D. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract three times with EA, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 120 g of compound 4, with a yield of 90.0%.

[0041] Example 5: Synthesis of Compound 1

[0042]

[0043] Dissolve 28.6 g of MsOH and 26.7 g of MsCl in 500 ml of THF. Place the reaction system in a cold trap. After the system temperature drops below 0 °C, add 100 g of Compound A. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract with EA three times, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 61.3 g of Product Compound 1, with a yield of 69.8%;

[0044] Example 6: Synthesis of Compound 2

[0045]

[0046] Dissolve 46.5 g of MsOH and 44.6 g of MsCl in 1500 mL of THF. Place the reaction system in a cold trap. After the system temperature drops below 0 °C, add 250 g of Compound B. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract with EA three times, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 102.7 g of Compound 2, with a yield of 44.4%.

[0047] Example 7: Synthesis of Compound 3

[0048]

[0049] Dissolve 32.8 g of MsOH and 33 g of MsCl in 600 mL of THF. Place the reaction system in a cold trap. After the system temperature drops below 0 °C, add 150 g of Compound C. After the addition is complete, bring the reaction to room temperature and stir until the reaction is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract with EA three times, collect the organic phase and wash the organic phase three times. Concentrate the organic phase to obtain 82.8 g of Compound 3, with a yield of 61.4%.

[0050] Example 8: Synthesis of Compound 4

[0051]

[0052] Dissolve 27.7 g of MsOH and 24.2 g of MsCl in 500 mL of 2-MeTHF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 100 g of compound D. After the addition is complete, bring the reaction to room temperature and stir the reaction until it is complete. Then, in an ice bath, add saturated aqueous sodium bicarbonate solution to the reaction system to quench the reaction. Extract with EA three times, collect the organic phase, and wash the organic phase three times. Concentrate the organic phase to obtain 45.7 g of compound 4 with a yield of 51.4%.

[0053] Comparative Example 1: Synthesis of Compound 1

[0054]

[0055] Dissolve 2.9 g of MsOH in 50 ml of THF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 10 g of the substrate. After the addition is complete, bring the reaction to room temperature and stir the reaction overnight. Detection shows that no product compound 1 is formed.

[0056] Comparative Example 2: Synthesis of Compound 1

[0057]

[0058] Dissolve 3 g of MsOH and 4.8 g of TsCl in 50 ml of THF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 10 g of compound A. After the addition is complete, bring the reaction to room temperature and stir the reaction overnight. Detection shows that there is no compound A and no compound 1.

[0059] Comparative Example 3: Synthesis of Compound 1

[0060]

[0061] Dissolve 4.8 g of TsCl in 50 ml of THF. Place the reaction system in a cold trap. After the temperature of the system drops below 0 °C, add 10 g of compound A. After the addition is complete, bring the reaction to room temperature and stir the reaction overnight. Detection shows that there is no compound A and no compound 1.

[0062] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art does not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a compound of formula I, characterized in that: The method comprises the following steps: reacting a compound of formula II in the presence of a sulfonylating agent and its corresponding acid in a solvent to obtain a compound of formula I; Its synthetic route is as follows: ； Wherein, R1 is selected from benzyl, tert-butyldiphenylsilyl, tert-butyldimethylsilyl, trimethylsilyl, trityl, p-methoxytrityl, dimethoxytrityl, naphthylmethyl or tetrahydropyranyl.

2. The preparation method according to claim 1, characterized in that: The solvent described in the above preparation method is selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, dichloromethane, N,N-dimethylformamide, N-methylpyrrolidone, acetonitrile, 1,2-dichloroethane, chloroform, methyl tert-butyl ether and diethyl ether.

3. The preparation method according to claim 1, characterized in that: The sulfonylating agent is selected from one of methanesulfonyl chloride and p-toluenesulfonyl chloride.

4. The preparation method according to claim 1, characterized in that: The acid corresponding to the sulfonylating agent is selected from methanesulfonic acid or p-toluenesulfonic acid.

5. The preparation method according to claim 4, characterized in that: The solvent is selected from tetrahydrofuran and 2-methyltetrahydrofuran.

6. The preparation method according to claim 1 or 2, characterized in that: The volume ratio of the solvent to the compound of formula II is 3-6:1, the molar ratio of the sulfonylating agent to the compound of formula II is 1.1-1.2:1, and the molar ratio of the acid corresponding to the sulfonylating agent to the compound of formula II is 1.3-1.5:1.

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