Preparation method of α-configuration deoxynucleoside

Abstract

The present application provides a method for preparing an α-configuration deoxynucleoside, which belongs to the technical field of nucleoside synthesis. The method for preparing an α-configuration deoxynucleoside comprises: reacting a mixed solution containing a deoxyribose raw material, a base raw material, and a polar aprotic solvent. The method for preparing an α-configuration deoxynucleoside provided by the present application uses a deoxyribose raw material of a specific structure as a starting material, and is combined with the selection of a polar aprotic solvent, which can allow the purine base raw material to react with the deoxyribose raw material, and promote the reaction to the target product α-configuration deoxynucleoside, inhibit the reaction to the by-product β-configuration deoxynucleoside, thereby increasing the conversion rate of the target product α-configuration deoxynucleoside, and thereby increasing the yield of the α-configuration deoxynucleoside. In addition, the method for preparing the α-configuration deoxynucleoside provided by the present application has a simple and easy synthesis process, which is conducive to industrial production.

Description

Technical Field

[0001] The present application relates to the technical field of nucleoside synthesis, and in particular to a method for preparing α-configuration deoxynucleoside. Background Art

[0002] Deoxynucleosides can be divided into α- and β-configurations based on the type of glycosidic bond. Purine deoxynucleosides with the α-configuration are the most basic raw materials for synthesizing α-configuration antisense oligonucleotides. α-configuration antisense oligonucleotides are molecular drugs that regulate gene expression by sequence-specifically binding to target gene DNA or mRNA, thereby inhibiting target gene expression.

[0003] However, during the reaction process, existing methods for synthesizing α-configuration purine deoxynucleosides simultaneously generate α-configuration purine deoxynucleosides and β-configuration purine deoxynucleosides, and the conversion rate of the target product α-configuration purine deoxynucleosides is low (i.e., the selectivity of the formation of α-configuration purine deoxynucleosides is low), resulting in a low yield of α-configuration purine deoxynucleosides. In addition, existing methods for synthesizing α-configuration purine deoxynucleosides are relatively complex and are not conducive to industrial production. Summary of the Invention

[0004] The purpose of the present application is to provide a method for preparing α-configuration deoxynucleosides, which aims to improve the technical problem of low conversion rate of α-configuration purine deoxynucleosides in existing methods for preparing α-configuration purine deoxynucleosides.

[0005] The present application provides a method for preparing α-configuration deoxynucleosides, comprising: reacting a mixed solution containing a deoxyribose raw material, a base raw material, and a polar aprotic solvent.

[0006] Among them, the structural formula of the deoxyribose raw material is as follows:

[0007]

[0008] R1 and R2 are each independently selected from protecting groups.

[0009] X is selected from a leaving group.

[0010] The base raw material is selected from any one of the compounds represented by the following structural formulas:

[0011]

[0012] R3 is selected from an amino group, an amino group substituted with a protecting group, a hydroxy group, a hydroxy group substituted with a protecting group, a halogen atom, a hydrogen atom, an alkyl group or an aryl group.

[0013] R4 and R6 are each independently selected from a hydrogen atom, an amino group substituted with a protecting group, a hydroxyl group substituted with a protecting group, a halogen atom, an alkyl group or an aryl group.

[0014] R5 and R7 are each independently selected from an amino group, an amino group substituted with a protecting group, a hydroxyl group, a hydroxyl group substituted with a protecting group, a halogen atom, a hydrogen atom, an alkyl group or an aryl group.

[0015] The preparation method of α-configuration deoxynucleosides provided by the present application uses a deoxyribose raw material with a specific structure as a starting material and is combined with the selection of a polar aprotic solvent to react a purine base raw material with a deoxyribose raw material, and promote the reaction to the target product α-configuration deoxynucleoside, inhibit the reaction to the by-product β-configuration deoxynucleoside conversion (i.e., increase the selectivity of the formation of α-configuration deoxynucleoside), thereby increasing the conversion rate of the target product α-configuration deoxynucleoside, and thus increasing the yield of α-configuration deoxynucleoside. In addition, the preparation method of α-configuration deoxynucleoside provided by the present application has a simple and easy synthesis process, which is conducive to industrial production.

[0016] In an optional embodiment of the present application, R3 is selected from an amino group substituted with a protecting group, a hydroxy group substituted with a protecting group, a halogen atom, a hydrogen atom, an alkyl group or an aryl group; and / or, R1 and R2 are each independently selected from an acetyl group, a benzoyl group, a benzyl group or a p-methylbenzoyl group; and / or, X is selected from a halogen atom, a trifluoromethanesulfonyloxy group, a methylsulfonyloxy group, a p-toluenesulfonyloxy group or an acetoxy group.

[0017] In the above technical solution, R1, R2, R3 and X are selected from the above groups, which can improve the conversion rate of the target product α-configuration deoxynucleoside.

[0018] In an optional embodiment of the present application, R1 and R2 are both p-methylbenzoyl; and / or, X is selected from a halogen atom; and / or, the base raw material is selected from any one of the compounds represented by the following structural formulas:

[0019] R3 is selected from a hydroxyl group substituted with a protecting group, a halogen atom or a C1-C6 alkyl group, R4 and R6 are each independently selected from a hydrogen atom or a C1-C6 alkyl group, and R5 and R7 are each independently selected from an amino group or an amino group substituted with a protecting group.

[0020] In an optional embodiment of the present application, X is selected from a fluorine atom, a chlorine atom, a bromine atom or an iodine atom; and / or the base raw material is selected from any one of the compounds represented by the following structural formula:

[0021] R3 is selected from a halogen atom, R4 and R6 are each independently selected from a hydrogen atom, and R5 and R7 are each independently selected from an amino group or an amino group substituted with an isobutyryl group.

[0022] In an optional embodiment of the present application, the polar aprotic solvent includes at least one of N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

[0023] In the above technical solution, the polar aprotic solvent is selected from the above solvent, which is conducive to improving the conversion rate of the target product α-configuration deoxynucleoside, inhibiting the reaction from converting the by-product β-configuration deoxynucleoside, improving the conversion rate of the target product α-configuration deoxynucleoside, and thus improving the yield of α-configuration deoxynucleoside.

[0024] In an optional embodiment of the present application, the mixed solution further contains a promoter, which is an ionizable - of substance.

[0025] In the above technical solution, the mixed solution contains a promoter, which can accelerate the reaction rate of the base raw material and the deoxyribose raw material, and also increase the conversion rate of the target product α-configuration deoxynucleoside, thereby increasing the yield of α-configuration deoxynucleoside.

[0026] Optionally, the promoter includes at least one of sodium iodide, potassium iodide, ammonium iodide and tetra-n-butylammonium iodide, which is beneficial to accelerating the reaction rate of the base raw material and the deoxyribose raw material and improving the conversion rate of α-configuration deoxynucleoside.

[0027] Optionally, the molar ratio of the deoxyribose raw material to the promoter is 1:(1-3), which can further increase the reaction rate of the base raw material and the deoxyribose raw material and increase the conversion rate of α-configuration deoxynucleoside.

[0028] In an optional embodiment of the present application, the molar ratio of the deoxyribose raw material to the base raw material is 1:(1.5-4).

[0029] In the above technical solution, the deoxyribose raw material and the base raw material are matched in the above ratios, so that the deoxyribose raw material can be fully converted into the target product α-configuration deoxynucleoside, thereby improving the conversion rate of the target product α-configuration deoxynucleoside.

[0030] In an optional embodiment of the present application, the base raw material is a base raw material that has been dried; and / or the polar aprotic solvent is a polar aprotic solvent that has been dried; and / or the reaction temperature is 10 to 40°C.

[0031] In the above technical solution, the substances in the reaction mixture are dried, which helps to avoid the situation where the presence of water in the reaction system results in a low amount of base starting material participating in the reaction and a large amount of unreacted deoxyribose starting material remaining, thereby improving the conversion rate of the target product, the α-configuration deoxynucleoside. The reaction temperature is 10-40°C, which helps to ensure the reaction rate and the conversion rate of the target product, the α-configuration deoxynucleoside, thereby improving production efficiency and the yield of the target product, the α-configuration deoxynucleoside.

[0032] In an optional embodiment of the present application, the structural formula of the base raw material is as follows:

[0033]

[0034] The preparation method of α-configuration deoxynucleoside further comprises: collecting the organic phase after the reaction and drying the organic phase; mixing the dried substance with acetonitrile, and then collecting the solid phase.

[0035] In the above technical solution, when the base raw material has the above structure, the target product α-configuration deoxynucleoside can be separated and obtained with high purity by acetonitrile crystallization. The separation and purification operation is simple and easy, which is conducive to industrial production.

[0036] Optionally, the mixing temperature is 10 to 50° C., and the mixing time is 2 to 5 hours.

[0037] In an optional embodiment of the present application, R1 and R2 are both p-methylbenzoyl groups. The method for preparing an α-configuration deoxynucleoside further comprises: after collecting the solid phase, removing R1 and R2. The step of removing R1 and R2 comprises: adding sodium methoxide to a mixture containing the solid phase and methanol at -15 to -5°C to obtain a mixed system; subjecting the mixed system to a deprotection reaction at -10 to 0°C for 1 to 2 hours; cooling the system after the deprotection reaction to ≤-15°C, and then adjusting the pH of the system after the deprotection reaction to 6 to 7.

[0038] In the above technical solution, when R1 and R2 are both p-methylbenzoyl groups, the p-methylbenzoyl protecting group can be effectively removed by the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0040] Figure 1This is the UPLC spectrum of the intermediate prepared in Example 1 of the present application.

[0041] Figure 2 The intermediate prepared in Example 1 of the present application 1 H NMR spectrum.

[0042] Figure 3 The intermediate prepared in Example 1 of the present application 1 H- 13 C HMBC spectrum.

[0043] Figure 4 This is the NOESY spectrum of the deoxynucleoside prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0044] During the reaction process, existing methods for synthesizing α-configuration purine deoxynucleosides simultaneously generate α-configuration purine deoxynucleosides and β-configuration purine deoxynucleosides. The conversion rate of the target product α-configuration purine deoxynucleosides is low (generally less than 20%), resulting in a low yield of α-configuration purine deoxynucleosides. In addition, existing methods for synthesizing α-configuration purine deoxynucleosides are relatively complex and are not conducive to industrial production.

[0045] To solve the above problems, the present application provides a method for preparing α-configuration deoxynucleosides, comprising: reacting a mixed solution containing a deoxyribose raw material, a base raw material and a polar aprotic solvent.

[0046] Among them, the structural formula of the deoxyribose raw material is as follows:

[0047]

[0048] R1 and R2 are each independently selected from a protecting group. X is selected from a leaving group.

[0049] The base raw material is selected from any one of the compounds represented by the following structural formulas:

[0050]

[0051] R3 is selected from amino, amino substituted with a protecting group, hydroxy, hydroxy substituted with a protecting group, halogen atom, hydrogen atom, alkyl or aryl. R4 and R6 are each independently selected from hydrogen atom, amino substituted with a protecting group, hydroxy substituted with a protecting group, halogen atom, alkyl or aryl. R5 and R7 are each independently selected from amino, amino substituted with a protecting group, hydroxy, hydroxy substituted with a protecting group, halogen atom, hydrogen atom, alkyl or aryl.

[0052] For the case where the structural formula of the base raw material is as follows:

[0053] The reaction pathway of the reaction between the base raw material and the deoxyribose raw material is as follows:

[0054]

[0055] Wherein, substance A is an α-configuration deoxynucleoside product; in the above reaction pathway, the active hydrogen bonded to the nitrogen atom on the base raw material reacts with the X atom on the deoxyribose raw material, so that the base raw material and the deoxyribose raw material are bonded to form an α-configuration deoxynucleoside.

[0056] For the case where the structural formula of the base raw material is as follows:

[0057] The reaction pathway of the reaction between the base raw material and the deoxyribose raw material is as follows:

[0058]

[0059] Wherein, substance B is an α-configuration deoxynucleoside product; in the above reaction pathway, the active hydrogen bonded to the nitrogen atom on the base raw material reacts with the X atom on the deoxyribose raw material, so that the base raw material and the deoxyribose raw material are bonded to form an α-configuration deoxynucleoside.

[0060] The preparation method of α-configuration deoxynucleosides provided in the present application uses a deoxyribose raw material with a specific structure as a starting material and is combined with the selection of a polar aprotic solvent. It can allow the purine base raw material to react with the deoxyribose raw material, promote the conversion of the reaction to the target product α-configuration deoxynucleoside, and inhibit the conversion of the reaction to the by-product β-configuration deoxynucleoside (i.e., increase the selectivity of the formation of α-configuration deoxynucleoside), thereby increasing the conversion rate of the target product α-configuration deoxynucleoside, and thereby increasing the yield of α-configuration deoxynucleoside.

[0061] In addition, the preparation method of the α-configuration deoxynucleoside provided in the present application has a simple and easy synthesis process, which is conducive to industrial production.

[0062] In some optional embodiments of the present application, R1 and R2 are each independently selected from acetyl, benzoyl, benzyl or p-methylbenzoyl; R1 and R2 are selected from the above groups to achieve an increase in the conversion rate of the target product α-configuration deoxynucleoside.

[0063] In some optional embodiments of the present application, X is selected from a halogen atom, a trifluoromethanesulfonyloxy group (-OTf), a methylsulfonyloxy group (-OMs), a p-toluenesulfonyloxy group (-OTs), or an acetoxy group (-OAc). X is selected from the above groups to increase the conversion rate of the target product α-configuration deoxynucleoside.

[0064] Furthermore, in the embodiments of the present application, R1 and R2 are both p-methylbenzoyl. The p-methylbenzoyl group has the following structural formula:

[0065]

[0066] Furthermore, in an embodiment of the present application, X is selected from a halogen atom, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0067] It should be noted that, in other feasible embodiments, R1 and R2 may also be independently selected from other protecting groups; and X may also be selected from other leaving groups.

[0068] As an example, in the examples of the present application, the deoxyribose raw material is 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose, and its structural formula is as follows:

[0069]

[0070] In the above formula, Tol is p-methylbenzoyl.

[0071] In some optional embodiments of the present application, R3 is selected from a protecting group-substituted amino group, a protecting group-substituted hydroxyl group, a halogen atom, a hydrogen atom, an alkyl group, or an aryl group. R3 is selected from the above groups to increase the conversion rate of the target product α-configuration deoxynucleoside.

[0072] Furthermore, when R4, R5, R6 and R7 are each independently selected from an alkyl group, the alkyl group is a C1-C6 alkyl group.

[0073] In some optional embodiments of the present application, the base raw material is selected from any one of the compounds represented by the following structural formulas:

[0074] R3 is selected from a hydroxyl group substituted with a protecting group, a halogen atom or a C1-C6 alkyl group, R4 and R6 are each independently selected from a hydrogen atom or a C1-C6 alkyl group, and R5 and R7 are each independently selected from an amino group or an amino group substituted with a protecting group.

[0075] Furthermore, the base raw material is selected from any one of the compounds represented by the following structural formulas:

[0076] R3 is selected from a halogen atom, R4 and R6 are each independently selected from a hydrogen atom, and R5 and R7 are each independently selected from an amino group or an amino group substituted with an isobutyryl group.

[0077] As an example, in the embodiments of the present application, the base raw material is selected from any one of the compounds represented by the following structural formulas:

[0078]

[0079] In some optional embodiments of the present application, the molar ratio of the deoxyribose raw material to the base raw material is 1:(1.5-4); under the above-mentioned ratio conditions, the deoxyribose raw material and the base raw material can fully convert the deoxyribose raw material into the target product α-configuration deoxynucleoside, thereby improving the conversion rate of the target product α-configuration deoxynucleoside.

[0080] As an example, the molar ratio of the deoxyribose raw material to the base raw material can be any one of 1:1.5, 1:1.7, 1:2, 1:2.2 and 1:2.5, or a range between any two of them.

[0081] It should be noted that, in other feasible embodiments, the molar ratio of the deoxyribose raw material to the base raw material is not limited to 1:(1.5-4). For example, the molar ratio of the deoxyribose raw material to the base raw material can be 1:1 or 1:5, etc.

[0082] In some optional embodiments of the present application, the polar aprotic solvent includes at least one of N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO). When the polar aprotic solvent is selected from the above solvents, it is beneficial to achieve an increase in the conversion rate of the target product α-configuration deoxynucleoside, inhibit the reaction from converting to the by-product β-configuration deoxynucleoside, increase the conversion rate of the target product α-configuration deoxynucleoside, and thereby increase the yield of the α-configuration deoxynucleoside.

[0083] As an example, in the examples of the present application, the polar aprotic solvent is selected from DMF, which is beneficial to further improve the conversion rate of the target product α-configuration deoxynucleoside.

[0084] In some optional embodiments of the present application, in addition to the deoxyribose raw material, the base raw material and the polar aprotic solvent, the mixed solution for the reaction further contains a promoter, which is an ionizable - (i.e. iodine negative ions) substances.

[0085] The mixed solution contains a promoter, which can accelerate the reaction rate of the base raw material and the deoxyribose raw material, and can also increase the conversion rate of the target product α-configuration deoxynucleoside, thereby increasing the yield of the α-configuration deoxynucleoside.

[0086] Furthermore, the promoter includes at least one of sodium iodide, potassium iodide, ammonium iodide and tetra-n-butylammonium iodide; the selection of the above substances as the promoter is conducive to accelerating the reaction rate of the reaction between the base raw material and the deoxyribose raw material and improving the conversion rate of the α-configuration deoxynucleoside.

[0087] As an example, in the examples of the present application, sodium iodide is selected as the promoter, which is beneficial to further improve the conversion rate of α-configuration deoxynucleosides.

[0088] In some optional embodiments of the present application, the molar ratio of the deoxyribose raw material to the promoter is 1:(1-3); under the above-mentioned ratio conditions, the deoxyribose raw material and the promoter can further increase the reaction rate of the reaction between the base raw material and the deoxyribose raw material and increase the conversion rate of α-configuration deoxynucleosides.

[0089] As an example, the molar ratio of the deoxyribose raw material to the promoter can be any one of 1:0.1, 1:0.5, 1:1.0, 1:1.2, 1:1.5, 1:1.7, 1:2 and 1:2.2, or a range between any two of them.

[0090] It should be noted that in other feasible embodiments, the molar ratio of the deoxyribose raw material to the accelerator is not limited to 1: (1-3). For example, the molar ratio of the deoxyribose raw material to the accelerator can be 1:0.5 or 1:4, etc. In other feasible embodiments, the accelerator may not be used.

[0091] To further improve the conversion rate of the target α-configuration deoxynucleoside, in some optional embodiments of the present application, the substances in the reaction mixture are dried. For example, the base raw material in the mixture is a dried base raw material; and / or the polar aprotic solvent in the mixture is a dried polar aprotic solvent.

[0092] The substances in the reaction mixture are dried to avoid the situation where there are fewer base raw materials participating in the reaction and more deoxyribose raw materials remaining that do not participate in the reaction due to the presence of water in the reaction system, thereby helping to increase the conversion rate of the target product α-configuration deoxynucleoside.

[0093] Furthermore, in the case where the mixed solution for the reaction contains an accelerator, the accelerator in the mixed solution is a dried accelerator.

[0094] As an example, the KF of the mixed solution for the reaction is <150ppm, which is beneficial to avoid the situation where there are fewer base raw materials participating in the reaction and more deoxyribose raw materials remaining that do not participate in the reaction due to the presence of water in the reaction system, thereby helping to improve the conversion rate of the target product α-configuration deoxynucleoside.

[0095] In some optional embodiments of the present application, the reaction temperature of the mixed solution containing the deoxyribose raw material, the base raw material and the polar aprotic solvent is 10 to 40° C.; the reaction temperature within the above temperature range is conducive to ensuring the reaction rate and the conversion rate of the target product α-configuration deoxynucleoside, thereby improving the production efficiency and the yield of the target product α-configuration deoxynucleoside.

[0096] Illustratively, the reaction temperature can be any one of 10°C, 15°C, 18°C, 20°C, 22°C, 25°C, 27°C, 30°C, 35°C and 40°C, or a range between any two of them.

[0097] In some optional embodiments of the present application, the reaction time of the mixed solution containing the deoxyribose raw material, the base raw material and the polar aprotic solvent is 5 to 24 hours; the reaction time within the above time range is conducive to ensuring the progress of the reaction.

[0098] As an example, the reaction time can be any one of 5 h, 7 h, 10 h, 12 h, 15 h, 17 h, 20 h, 22 h and 24 h, or a range between any two of them.

[0099] In some optional embodiments of the present application, the method for preparing α-configuration deoxynucleosides further comprises: after reacting a mixture containing a deoxyribose raw material, a base raw material, and a polar aprotic solvent, isolating and obtaining an α-configuration deoxynucleoside intermediate (i.e., an α-configuration deoxynucleoside protected by a protecting group).

[0100] As an example, in the examples of the present application, the base raw material is N2-iBu guanine, and its structural formula is as follows:

[0101] The steps of isolating and obtaining the α-configuration deoxynucleoside intermediate include: collecting the organic phase after the reaction (ie, after the mixed solution reacts), and drying the organic phase; mixing the dried substance with acetonitrile, and then collecting the solid phase.

[0102] When the structural formula of the base raw material is selected from the substance corresponding to the above structural formula (i.e., N2-iBu guanine), in the presence of a polar aprotic solvent, the reaction can form a system having an N9-α configuration deoxynucleoside intermediate (i.e., substance A), an N7-α configuration deoxynucleoside intermediate, an N9-β configuration deoxynucleoside intermediate, and an N7-β configuration deoxynucleoside intermediate. The conversion rate of the α configuration deoxynucleoside intermediate is much higher than that of the β configuration deoxynucleoside intermediate, and the conversion rate of the N9-α configuration deoxynucleoside intermediate is also much higher than that of the N7-α configuration deoxynucleoside intermediate. The N9-α configuration deoxynucleoside intermediate with high purity (more than 98.5%) is separated by acetonitrile crystallization. The separation and purification operation is simple and easy, which is conducive to industrial production. Among them, the structural formula of the N7-α configuration deoxynucleoside intermediate is as follows:

[0103]

[0104] The structural formula of the N9-β deoxynucleoside intermediate is as follows:

[0105]

[0106] The structural formula of the N7-β deoxynucleoside intermediate is as follows:

[0107]

[0108] Furthermore, the mixing temperature of the dried substance and acetonitrile is 10-50° C., and the mixing time is 2-5 hours. Such a mixing temperature and mixing time are beneficial for increasing the amount of the collected N9-α deoxynucleoside intermediate, thereby increasing the yield of the N9-α deoxynucleoside.

[0109] Furthermore, after the dried substance is mixed with acetonitrile, the step of "collecting the solid phase" includes: filtering the system after the dried substance and acetonitrile are mixed, stirring and crystallizing with 5 to 10 times the volume of acetonitrile at 10 to 50°C for 2 to 5 hours, and then filtering, and the obtained filter cake is suspended and slurried with 2 to 3 times the volume of acetonitrile at 10 to 50°C for further purification 2 to 3 times.

[0110] It should be noted that, for the case where different base raw materials are used in the reaction, the method for isolating the α-configuration deoxynucleoside intermediate from the reaction system can be silica gel chromatography purification or reverse phase chromatography column (e.g., C18 reverse phase chromatography column), etc., as long as the α-configuration deoxynucleoside intermediate can be isolated, this application does not limit it.

[0111] As an example, when the base raw material is N2-iBu guanine, before mixing the dried substance with acetonitrile, the step of "collecting the organic phase after the reaction and drying the organic phase" includes: pouring the system after the reaction into a mixture of 35 to 40 times the volume of ethyl acetate and 120 to 170 times the volume of 0.3 to 0.7 wt% sodium bicarbonate solution, stirring thoroughly for 10 to 15 minutes and then filtering, rinsing the filter cake once with 10 to 30 times the volume of ethyl acetate, separating the organic phase in the filtrate, back-extracting the aqueous phase with 20 to 40 times the volume of ethyl acetate twice, combining all the organic phases, washing 2 to 4 times with 70 to 90 times the volume of 1 to 3 wt% sodium chloride solution, drying over anhydrous sodium sulfate, and concentrating under reduced pressure to obtain a solid crude product.

[0112] Furthermore, in some optional embodiments of the present application, the method for preparing α-configuration deoxynucleoside further comprises: after isolating the α-configuration deoxynucleoside intermediate, removing the protecting group on the α-configuration deoxynucleoside intermediate.

[0113] As an example, in the examples of the present application, the structural formulas of the base raw material and the deoxyribose raw material are respectively as follows:

[0114] wherein Tol is a p-methylbenzoyl group. The step of removing the protecting group (i.e., the p-methylbenzoyl group) from the α-configuration deoxynucleoside intermediate comprises: after collecting the solid phase, adding sodium methoxide to a mixture containing the solid phase and methanol at -15 to -5°C to obtain a mixed system; subjecting the mixed system to a deprotection reaction at -10 to 0°C for 1 to 2 hours; cooling the system after the deprotection reaction to ≤-15°C, and then adjusting the pH of the system after the deprotection reaction to 6 to 7.

[0115] Furthermore, after the pH of the system after the deprotection reaction is adjusted to 6-7, the target product α-configuration deoxynucleoside can be obtained by purification by acetonitrile and water suspension. As an example, after the pH of the system after the deprotection reaction is adjusted to 6-7, the system after the pH adjustment is concentrated and dried under reduced pressure, and then concentrated once with methanol, 8-10 times the volume of acetonitrile is added, and the mixture is suspended and stirred at 10-25°C for 2-3 hours, filtered, and the filter cake is rinsed once with a small amount of acetonitrile, and vacuum dried to obtain a crude product. The crude product is suspended and stirred with 3-5 times deionized water at 10-45°C for 2-3 hours and then filtered. The filter cake is further suspended and stirred with 1-2 times deionized water at 10-45°C for 2-3 hours and then filtered. The filter cake is rinsed once with a small amount of deionized water and vacuum dried to obtain a high-purity target product α-configuration deoxynucleoside.

[0116] It should be noted that the removal of the p-methylbenzoyl group on the α-configuration deoxynucleoside intermediate can also be done by other conventional methods for removing the p-methylbenzoyl protecting group; if the protecting group on the α-configuration deoxynucleoside intermediate is other groups, the removal of the corresponding protecting group can also be done by conventional methods in the prior art, which is not limited in this application.

[0117] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0118] Example 1

[0119] This embodiment provides a method for preparing an α-configuration deoxynucleoside, comprising the following steps:

[0120] (1) 62.6 g of N2-iBu guanine was added to a 5.0 L round-bottom flask. After dehydration with 1.0 L of dry acetonitrile three times, 2.5 L of dry DMF was added. After thorough mixing, the mixture was allowed to stand for 7 min to obtain a mixed system with a KF < 150 ppm.

[0121] (2) At 20° C., 28.9 g of NaI solid and 50 g of 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose solid were added to the mixed system obtained in step (1) in sequence under stirring. After the stirring reaction was continued for 10 h, the reaction mixture was taken and monitored by UPLC. At a wavelength of 260 nm, all peaks except N2-iBu guanine were integrated. The main peak and impurity content were calculated by peak area normalization method. If the content of N9-α configuration deoxynucleoside product was greater than 38% and the total amount of MS 925 impurities was less than 2%, the reaction was considered qualified. Otherwise, the reaction was continued until the reaction was qualified; and the initial product system was obtained.

[0122] (3) Stop stirring the reaction, pour the initial product system obtained in step (2) into a mixture of 2.0 L of ethyl acetate and 7.5 L of a 0.5 wt% aqueous solution of NaHCO3, add 50.0 g of diatomaceous earth, stir for 10 min, and filter. Rinse the filter cake with 1.0 L of ethyl acetate, separate the organic phase from the filtrate, back-extract the aqueous phase twice with 1.5 L of ethyl acetate, combine all the organic phases, wash three times with 4.0 L of a 2 wt% aqueous solution of NaCl, and then dry over anhydrous sodium sulfate and concentrate under reduced pressure to obtain a crude brown solid.

[0123] (4) The brown solid crude product obtained in step (3) was concentrated to dryness once with 400 mL of acetonitrile, and then 350 mL of acetonitrile was added. After stirring and crystallization at 45°C for 2 h, the mixture was naturally cooled to 15°C, stirred for 5 h, filtered, and the filter cake was vacuum dried to obtain an off-white solid. The off-white solid was suspended and stirred with 150 mL of acetonitrile at 45°C for 4 h, cooled to 15°C, filtered, and the filter cake was rinsed with a small amount of acetonitrile and suspended again to obtain an intermediate.

[0124] (5) The intermediate obtained in step (4) was mixed with 250 mL of methanol to obtain a mixed solution; 7.0 g of sodium methoxide was added to the mixed solution at -10°C; the mixture was then reacted at -5°C for 1.5 h, cooled to -15°C, and the pH of the system was adjusted to 7. The system after pH adjustment was concentrated and dried under reduced pressure, concentrated once with methanol, added with 250 mL of acetonitrile, suspended and stirred at 20°C for 2.5 h, filtered, the filter cake was rinsed once with a small amount of acetonitrile, and vacuum dried to obtain a crude product. The crude product was suspended and stirred with 108 mL of deionized water at 20°C for 2.5 h, then filtered, the filter cake was further suspended and stirred with 27.5 mL of deionized water at 20°C for 2.5 h, then filtered, the filter cake was rinsed once with a small amount of deionized water, and vacuum dried to obtain a deoxynucleoside.

[0125] Example 2

[0126] This embodiment provides a method for preparing an α-configuration deoxynucleoside, comprising the following steps:

[0127] (1) 2.73 g of 2-amino-6-chloropurine was added to a 100 mL round-bottom flask. After dehydration with 50 mL of dry acetonitrile, 50 mL of dry DMF was added. After thorough mixing, the mixture was allowed to stand for 7 minutes to obtain a mixed system.

[0128] (2) 1.45 g of NaI solid and 2.5 g of 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose solid were added to the mixed system obtained in step (1) at 15° C. with stirring. The reaction was continued with stirring for 12 h. The reaction mixture was then monitored by UPLC. All peaks were integrated at a wavelength of 260 nm. The main peak and impurity content were calculated by peak area normalization. If the content of the N9-α configuration deoxynucleoside product was greater than 30% and the total amount of MS 873 impurities was less than 12%, the reaction was considered qualified. Otherwise, the reaction was continued until the reaction was qualified. The initial product system was obtained.

[0129] (3) Stop stirring the reaction, pour the initial product system obtained in step (2) into a mixture of 120 mL of ethyl acetate and 120 mL of a 0.5 wt% NaHCO3 aqueous solution, stir for 4 min, filter, separate the organic phase from the filtrate, wash five times with 120 mL of deionized water, dry over anhydrous sodium sulfate, and concentrate under reduced pressure to obtain a crude yellow solid.

[0130] Example 3

[0131] This example provides a method for preparing an α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of N2-iBu guanine is 71.1 g.

[0132] Example 4

[0133] This example provides a method for preparing an α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of N2-iBu guanine is 42.7 g.

[0134] Example 5

[0135] This example provides a method for preparing an α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of N2-iBu guanine is 28.5 g.

[0136] Example 6

[0137] This example provides a method for preparing an α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of N2-iBu guanine is 113.8 g.

[0138] Example 7

[0139] This embodiment provides a method for preparing α-configuration deoxynucleoside. The difference between this embodiment and Example 1 is that the mass of NaI is 42.4 g.

[0140] Example 8

[0141] This example provides a method for preparing an α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of NaI is 19.3 g.

[0142] Example 9

[0143] This example provides a method for preparing α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of NaI is 3.9 g.

[0144] Example 10

[0145] This example provides a method for preparing α-configuration deoxynucleoside. The difference between this example and Example 1 is that the mass of NaI is 57.8 g.

[0146] Example 11

[0147] This example provides a method for preparing an α-configuration deoxynucleoside. The difference between this example and Example 1 is that 28.9 g of NaI in Example 1 is replaced by 27.9 g of ammonium iodide.

[0148] Example 12

[0149] This example provides a method for preparing α-configuration deoxynucleoside. The difference between this example and Example 1 is that NaI is not used in this example.

[0150] Example 13

[0151] This example provides a method for preparing α-configuration deoxynucleosides. The difference between this example and Example 1 is that DMF in Example 1 is replaced by DMSO.

[0152] Example 14

[0153] This embodiment provides a method for preparing an α-configuration deoxynucleoside. The difference between this embodiment and Example 1 is that step (1) is different. Step (1) of this embodiment is as follows:

[0154] 62.6 g of N2-iBu guanine was thoroughly mixed with 2.5 L of DMF and allowed to stand for 7 minutes to obtain a mixed system with a KF of 2000 ppm.

[0155] Example 15

[0156] This example provides a method for preparing α-configuration deoxynucleoside. The difference between this example and Example 1 is that the reaction temperature in step (2) is 10°C.

[0157] Example 16

[0158] This embodiment provides a method for preparing α-configuration deoxynucleoside. The difference between this embodiment and Example 1 is that the reaction temperature in step (2) is 40°C.

[0159] Example 17

[0160] This embodiment provides a method for preparing α-configuration deoxynucleoside. The difference between this embodiment and Example 1 is that the reaction temperature in step (2) is 0°C.

[0161] Example 18

[0162] This embodiment provides a method for preparing α-configuration deoxynucleoside. The difference between this embodiment and Example 1 is that the reaction temperature in step (2) is 60°C.

[0163] Experimental Example 1

[0164] The intermediate prepared in Example 1 was characterized by ultra-high performance liquid chromatography (UPLC). Figure 1 shown.

[0165] from Figure 1 It can be seen that in the intermediate prepared in step (4) of Example 1, the purity of the deoxynucleoside product with N9-α configuration is 98.52%, the deoxynucleoside product with N7-α configuration and the deoxynucleoside product with N9-β configuration account for 0.58% and 0.70%, respectively; indicating that the preparation method of Example 1 of the present application can obtain a product with N9-α configuration with higher purity.

[0166] The intermediate prepared in Example 1 was subjected to H NMR spectroscopy ( 1 H NMR) and 1 H- 13 C heteronuclear multiple bond correlation spectrum ( 1 H- 13 C HMBC) characterization, the characterization results are as follows Figure 2 and Figure 3 shown.

[0167] Figure 2 middle, 1 H NMR(500MHz,CDCl3):12.20(s,1H,1-NH),10.32(s,1H,iBu-NH),8.04(s,1H,8-H), 7.85(d,J=8.0Hz,2H,Tol-CH),7.62(d,J=8.0Hz,2H,Tol-CH),7.17(d,J=8.0Hz,2H ,Tol-CH),7.13(d,J=8.0Hz,2H,Tol-CH),6.20(dd,J=5.0,3.5Hz,1H,1'-H),5.62- 5.56(m,1H,3'-H),4.82-4.73(m,1H,4'-H),4.50(d,J=4.5Hz,2H,5'-H),2.90(sep,

[0168] J=7.0Hz,1H,iBu-CH),2.84-2.80(m,2H,2'-H),2.351(s,3H,Tol-CH3),2.345(s,3H,T

[0169] ol-CH3), 1.22 (d, J=7.0Hz, 3H, iBu-CH3), 1.21 (d, J=7.0Hz, 3H, iBu-CH3), from Figure 2 Can

[0170] It can be seen that the structure of the intermediate prepared in Example 1 (without removal of the methylbenzoyl protecting group) is consistent with the expected intermediate.

[0171] Figure 3 middle, 1 H- 13 The C HMBC spectrum showed that there was no carbon-hydrogen long-range correlation between the 1'-H on the sugar ring and the 5-C of the base in the obtained compound, but there was a carbon-hydrogen long-range correlation between the 1'-H on the sugar ring and the 4-C of the base, indicating that the N9 position of the base was connected to the sugar ring.

[0172] The deoxynucleoside prepared in Example 1 was characterized by NOESY spectra. The characterization results are as follows: Figure 4 shown.

[0173] Figure 4 In the figure, there are NOE-related signals between the 8-H base and the 4'-H and 3'-OH groups on the sugar ring, but there is no NOE-related signal between the 8-H base and the 3'-H group on the sugar ring. This indicates that the obtained deoxynucleoside (product, i.e., the p-methylbenzoyl protecting group has been removed) is of α-configuration.

[0174] Experimental Example 2

[0175] The conversion rates of the deoxynucleoside product with N9-α configuration (denoted as N9-α), the deoxynucleoside product with N7-α configuration (denoted as N7-α), the deoxynucleoside product with N9-β configuration (denoted as N9-β), and the deoxynucleoside product with N7-β configuration (denoted as N7-β) in the initial product system obtained in Example 1-18 (i.e., the system obtained in step (2)) were measured, and the measurement results are shown in Table 1.

[0176] Table 1

[0177]

[0178] As can be seen from Table 1, the preparation method of α-configuration deoxynucleosides provided in the present application can achieve a conversion rate of α-configuration deoxynucleosides of 29.5% or above.

[0179] From the comparison of Example 1 and Examples 3-6, it can be seen that compared with the molar ratio of the deoxyribose raw material (i.e., 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose) to the base raw material (i.e., N2-iBu guanine) of 1:1 in Example 5, when the molar ratio of the deoxyribose raw material to the base raw material is 1:(1.5-4), the conversion rate of the α-configuration deoxynucleoside can be further increased to 36.3% or above.

[0180] From the comparison of Example 1 and Examples 7-10, it can be seen that compared with the molar ratio of the deoxyribose raw material (i.e., 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose) to the promoter (i.e., NaI) of 1:0.2 in Example 9, when the molar ratio of the deoxyribose raw material to the promoter is 1:(1-3), the conversion rate of the α-configuration deoxynucleoside can be further increased to 35.7% or above.

[0181] From the comparison between Example 1 and Example 11, it can be seen that, compared with using ammonium iodide as the promoter in Example 11, using NaI as the promoter in Example 1 is beneficial to further improving the conversion rate of α-configuration deoxynucleoside.

[0182] From the comparison between Example 1 and Example 12, it can be seen that, compared with Example 12 in which no promoter NaI is used, the use of promoter NaI in Example 1 is beneficial to further improve the conversion rate of α-configuration deoxynucleoside.

[0183] From the comparison between Example 1 and Example 13, it can be seen that compared with the use of DMSO as the solvent in Example 13, the use of DMF as the solvent in Example 1 is beneficial to further improve the conversion rate of α-configuration deoxynucleosides.

[0184] From the comparison between Example 1 and Example 14, it can be seen that compared with Example 14 in which the base raw material (i.e., N2-iBu guanine) and the solvent (i.e., DMF) were not dehydrated or dried, Example 1 in which the base raw material was dehydrated and the solvent was dried, the conversion rate of the α-configuration deoxynucleoside was improved.

[0185] From the comparison of Example 1 and Examples 15-18, it can be seen that compared with the reaction temperature of the deoxyribose raw material (i.e., 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose) and the base raw material (i.e., N2-iBu guanine) at 0°C or 60°C, the reaction temperature of the deoxyribose raw material and the base raw material (i.e., 1-chloro-3,5-di-O-p-toluoyl-2-deoxy-D-ribofuranose) at 10-40°C is conducive to further improving the conversion rate of α-configuration deoxynucleosides.

[0186] In summary, the preparation method of α-configuration deoxynucleosides provided by the present application uses a deoxyribose raw material with a specific structure as a starting material, and is combined with the selection of a polar aprotic solvent, which can allow the base raw material to react with the deoxyribose raw material, and promote the reaction to the target product α-configuration deoxynucleoside, inhibit the reaction to the by-product β-configuration deoxynucleoside, thereby increasing the conversion rate of the target product α-configuration deoxynucleoside, and thus increasing the yield of α-configuration deoxynucleoside. In addition, the preparation method of α-configuration deoxynucleoside provided by the present application is simple and easy to synthesize, which is conducive to industrial production.

[0187] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A method for preparing an α-configuration deoxynucleoside, characterized in that: include: reacting a mixture containing a deoxyribose raw material, a base raw material, and a polar aprotic solvent; The polar aprotic solvent includes at least one of N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; Wherein, the structural formula of the deoxyribose raw material is as follows: ； R1 and R2 are each independently selected from a protecting group; X is selected from a leaving group; The base raw material is selected from any one of the compounds represented by the following structural formula: 、 ； R3 is selected from amino, amino substituted with a protecting group, hydroxy, hydroxy substituted with a protecting group, a halogen atom or a hydrogen atom; R4 and R6 are each independently selected from a hydrogen atom, an amino group substituted with a protecting group, a hydroxyl group substituted with a protecting group, a halogen atom or a C1-C6 alkyl group; R5 and R7 are each independently selected from an amino group, an amino group substituted with a protecting group, a hydroxyl group, a hydroxyl group substituted with a protecting group, a halogen atom, a hydrogen atom or a C1-C6 alkyl group.

2. The preparation method according to claim 1, characterized in that R3 is selected from amino substituted by a protecting group, hydroxy substituted by a protecting group, a halogen atom or a hydrogen atom; and / or, said R1 and said R2 are each independently selected from acetyl, benzoyl, benzyl or p-methylbenzoyl; And / or, X is selected from a halogen atom, a trifluoromethanesulfonyloxy group, a methylsulfonyloxy group, a p-toluenesulfonyloxy group or an acetoxy group.

3. A method for preparing an α-configuration deoxynucleoside, characterized in that: include: reacting a mixture containing a deoxyribose raw material, a base raw material, and a polar aprotic solvent; The polar aprotic solvent includes at least one of N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; Wherein, the structural formula of the deoxyribose raw material is as follows: ； Said R1 and said R2 are both p-methylbenzoyl; Said X is selected from halogen atoms; The base raw material is selected from any one of the compounds represented by the following structural formula: 、 ; and said R3 is selected from a hydroxyl group substituted with a protecting group, a halogen atom or a C1-C6 alkyl group, said R4 and said R6 are each independently selected from a hydrogen atom or a C1-C6 alkyl group, and said R5 and said R7 are each independently selected from an amino group or an amino group substituted with a protecting group.

4. The preparation method according to claim 1, characterized in that The X is selected from a fluorine atom, a chlorine atom, a bromine atom or an iodine atom; And / or, the base raw material is selected from any one of the compounds represented by the following structural formula: 、 ; and said R3 is selected from a halogen atom, said R4 and said R6 are each independently selected from a hydrogen atom, and said R5 and said R7 are each independently selected from an amino group or an amino group substituted with isobutyryl.

5. The preparation method according to claim 1, characterized in that The mixed solution also contains a promoter, which is ionizable. - of substance.

6. The preparation method according to claim 5, characterized in that The accelerator includes at least one of sodium iodide, potassium iodide, ammonium iodide and tetra-n-butylammonium iodide.

7. The preparation method according to claim 5, characterized in that The molar ratio of the deoxyribose raw material to the accelerator is 1:(1-3).

8. The preparation method according to any one of claims 1 to 7, characterized in that The molar ratio of the deoxyribose raw material to the base raw material is 1:(1.5-4).

9. The preparation method according to any one of claims 1 to 7, characterized in that The base raw material is a base raw material that has been dried; And / or, the polar aprotic solvent is a polar aprotic solvent that has been dried; And / or, the reaction temperature is 10-40°C.

10. The preparation method according to claim 1, characterized in that The structural formula of the base raw material is as follows: ； The method for preparing the α-configuration deoxynucleoside further comprises: collecting the organic phase after the reaction and drying the organic phase; mixing the dried substance with acetonitrile, and then collecting the solid phase.

11. The preparation method according to claim 10, characterized in that: The mixing temperature is 10-50° C., and the mixing time is 2-5 hours.

12. The preparation method according to claim 10, characterized in that Said R1 and said R2 are both p-methylbenzoyl; The method for preparing the α-configuration deoxynucleoside further comprises: after collecting the solid phase, removing the R1 and the R2; The step of removing the R1 and the R2 includes: adding sodium methoxide to a mixed solution containing the solid phase and methanol at -15 to -5°C to obtain a mixed system; performing a deprotection reaction on the mixed system at -10 to 0°C for 1 to 2 hours; cooling the system after the deprotection reaction to ≤-15°C, and then adjusting the pH of the system after the deprotection reaction to 6 to 7.

Images