Preparation method of compound

Abstract

The invention relates to a divisional application of which the application number is 202411336357.7. The invention relates to a preparation method of a compound, which comprises the following steps: a mixture is contacted with an organic base under the condition that a silyl migration reaction can be carried out, the mixture contains a compound shown in a formula (II) and an organic solvent, and the organic solvent is a solvent which is slightly soluble in a compound shown in a formula (I) at normal temperature. In the compound of the formula (I) and the compound of the formula (II), R1 is a silyl protecting group; r2 is a non-silyl protecting group; r < 3 >, R < 4 >, R < 5 > and R < 6 > are respectively and independently one of hydrogen and C1-C4 alkyl; and B is a group which has a molecular weight of 50-420 and does not participate in a silane migration reaction. The method has few operation steps, most byproducts are converted into products, the total yield is improved, and the method is suitable for industrial production.

Description

[0001] This application is a divisional application. The parent application has the application number 202411336357.7, the application date is September 25, 2024, and the invention title is "A method for preparing a compound". Technical Field

[0002] This disclosure belongs to the field of medicinal chemistry technology, and specifically relates to a method for preparing a compound. Background Technology

[0003] Phosphoramide nucleoside monomers are key starting materials for the synthesis of small nucleic acid drugs. The nucleoside intermediates used in their preparation, where the 5' and 2' hydroxyl groups on the ribose ring are protected while the 3' hydroxyl group remains unprotected, are also crucial intermediates in the preparation of phosphoramide nucleoside monomers. In this field, the 2' hydroxyl protecting group commonly uses a silane protecting group.

[0004] Non-patent literature (Damha MJ, Ogilvie KK (1993), Oligonucleotide synthesis: thsilyl-phosphoramidite method. In: Protocols for Oligonucleotides and Analogs: Synthesis and Properties, Methods in Molecular Biology (Agrawal S, ed.) Vol. 20. Totowa, NJ: The Humana Press Inc. pp. 81-114) discloses that nucleic acid base monomers protected by tert-butyldimethylsilyl (TBDMS) or triisopropylsilyl (TIPS) readily generate a mixture of isomers with 2'- and 3'-hydroxyl groups having silane protecting groups during preparation. The 3'-silyl isomer can be isomerized to an equilibrium mixture of 2'- and 3'-silyl isomers in an approximately 1:1 ratio in an alkaline solution such as 9:1 pyridine:water (TBDMS protected) or 1% ammonia:ethanol (TIPS / N-Bz combination), increasing the recovery rate of the 3'-silyl isomer. However, the aqueous solution used in this method is not suitable for the anhydrous and oxygen-free system required by the nucleoside phosphoramidide process widely used in the current field of small nucleic acid drug synthesis, requiring additional product purification steps such as dehydration. Furthermore, this method only yields an equilibrium mixture of 2'- and 3'-silyl isomers, not a complete conversion, thus requiring additional separation steps to obtain the desired 2'-silyl isomer. Summary of the Invention

[0005] This disclosure provides a method for preparing a compound, the method comprising contacting a mixture with an organic base under conditions capable of silane migration reaction, wherein the mixture contains a compound of formula (II) and an organic solvent, the organic solvent being a solvent in which the compound of formula (I) is slightly soluble at room temperature:

[0006]

[0007] R1 is a silyl protecting group;

[0008] R2 is a non-silane hydroxyl protecting group;

[0009] R3, R4, R5 and R6 are each independently one of hydrogen or a C1-C4 alkyl group;

[0010] B is a group with a molecular weight between 50 and 420 that does not participate in silane migration reactions.

[0011] Beneficial effects

[0012] Compared to the traditional nucleoside monomer preparation process, which requires numerous steps to convert the 3'-isomer byproduct into the 2'-isomer and has a low overall product yield, the method of this invention has fewer steps, converts most of the byproduct into the product, and increases the overall yield, making it suitable for industrial production.

[0013] For example, column chromatography alone is insufficient to efficiently and in high yield obtain 2'-silica isomers with high purity, and large mixtures of 2'- and 3'-silica isomers are difficult to further separate. In contrast, the method disclosed herein can efficiently convert compounds of formula (II) in mixtures containing different formula (II) compounds and organic solvents into compounds of formula (I), and obtain compounds of formula (I) through solid-liquid separation, with a yield of at least 73.8% and a purity of at least 95.5% in the product. Furthermore, within a suitable range of organic base dosage, the method disclosed herein can achieve even higher conversion rates and higher product purity, with yields up to 89.3%; purity of at least 97.5 wt%, and even up to 98.2 wt%; and low content of byproducts and impurities in the final product, with the content of formula (II) compounds controlled to below 0.5 wt%, and even as low as 0.1 wt%.

[0014] Incorporate by reference

[0015] All publications, patents and patent applications mentioned in this specification are incorporated herein by reference to the same extent that each individual publication, patent or patent application is specifically and individually incorporated herein by reference. Detailed Implementation

[0016] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0017] Those skilled in the art will understand that for any group containing one or more substituents, these groups are not intended to introduce any substitution or substitution pattern that is spatially impractical, synthetically infeasible, and / or inherently unstable.

[0018] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. If a term has multiple definitions herein, the definition in that section shall prevail unless otherwise stated. The singular forms “a,” “an,” and “the” used in this specification and the appended claims include plural indicators unless the context clearly specifies otherwise. Unless otherwise stated, conventional methods of mass spectrometry, NMR, HPLC, protein chemistry, biochemistry, recombinant DNA techniques, and pharmacology are employed. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “comprising” is not restrictive.

[0019] While this disclosure has been described and illustrated in detail in the foregoing description, such descriptions should be considered illustrative or exemplary, and not restrictive. This disclosure is not limited to the disclosed embodiments. By studying this disclosure and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments in practice with respect to the claimed disclosure.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) shall be given their common and conventional meanings to those skilled in the art, and not limited to their particular or customary meanings, unless expressly defined herein. It should be noted that the use of a particular term in describing certain features or aspects of this disclosure should not be construed as indicating that the term is hereby redefined to include only any particular feature of this disclosure relating to that term.

[0021] When a numerical range is provided, it should be understood that the upper and lower limits, as well as each intermediate value between the upper and lower limits of the range, are included in the implementation.

[0022] As used herein, a “nucleoside” is structurally similar to a nucleotide but lacks a phosphate moiety. An example of a nucleoside analog is one in which the label is linked to a base and the sugar molecule does not have a phosphate group attached. The term “nucleoside” is used herein in its ordinary sense as understood by those skilled in the art. Examples include, but are not limited to, ribonucleosides containing a ribose moiety and deoxyribonucleosides containing a deoxyribose moiety. A modified pentose moiety is a pentose moiety in which an oxygen atom has been substituted by a carbon atom and / or a carbon atom has been substituted by a sulfur or oxygen atom. A “nucleoside” is a monomer that may have substituted and / or sugar moieties. Additionally, nucleosides can be incorporated into larger DNA and / or RNA polymers and oligomers.

[0023] As used herein, the terms “protecting group” and “multiple protecting groups” refer to any atom or group of atoms added to a molecule to prevent undesirable chemical reactions with existing groups in the molecule. Examples of protecting groups are described in TW Greene and PGM Uts, *Protective Groups in Organic Synthesis*, 3rd ed., John Wiley & Sons, 1999, and in JFW McOmie, *Protective Groups in Organic Chemistry*, Plenum Press, 1973, and are incorporated herein by reference only for the purpose of disclosing suitable protecting groups. Protecting groups are chosen in a manner that allows them to be stable to certain reaction conditions and to be removed at a convenient stage using methods known in the art. The non-limiting list of protecting groups includes benzyl (Bn); substituted benzyl; alkyl carbonyl (e.g., tert-butoxycarbonyl (BOC), acetyl (i.e., -C(=O)CH3 or Ac) or isobutyryl (iBu); arylalkyl carbonyl (e.g., benzyloxycarbonyl or benzoyl); silyl (e.g., trimethylsilyl (TMS), triethylsilyl, triisopropylsilyl), tert-butyldimethylsilyl (TBDMS), triisopropylsilyloxymethyl (TOM) or tert-butyldiphenylsilyl); and triarylmethyl groups (e.g., triphenylmethyl; monomethoxytriphenylmethyl (MMTr); 4,4”-dimethoxytriphenylmethyl (DMTr); or 4,4”,4”-trimethoxytriphenylmethyl (TMTr)).

[0024] As used herein, “derivative” or “analyte” means a synthetic nucleoside or nucleotide derivative having a modified base moiety and / or a modified sugar moiety. Such derivatives and analogs are discussed, for example, in Scheit, Nucleotide Analogs (John Willie & Sons, 1980) and Uhlman et al., Chemical Reviews 90:543-584, 1990. The terms “derivative” and “analyte” are used interchangeably herein and are covered by the term “nucleoside” as defined herein.

[0025] This disclosure provides a method for preparing a compound, the method comprising contacting a mixture with an organic base under conditions capable of silane migration reaction, wherein the mixture contains a compound of formula (II) and an organic solvent, the organic solvent being a solvent in which the compound of formula (I) is slightly soluble at room temperature:

[0026]

[0027] R1 is a silyl protecting group;

[0028] R2 is a non-silane hydroxyl protecting group;

[0029] R3, R4, R5 and R6 are each independently one of hydrogen or a C1-C4 alkyl group;

[0030] B is a group with a molecular weight between 50 and 420 that does not participate in silane migration reactions.

[0031] Without being theoretically limited, it is known in the art that, under conditions conducive to silane migration reactions, the 2'-hydroxyl and 3'-hydroxyl nucleoside intermediate isomers, one unprotected and the other protected by a silane protecting group, undergo isomerization in solution, and a dynamic equilibrium of interconversion exists between the different isomers. The inventors of this disclosure unexpectedly discovered that, due to the different solubilities of the 2'- and 3'-silyl isomers in the same solvent, the 2'-silyl isomer can be separated from the solvent by crystallization in a specific type of organic solvent. Thus, to maintain the aforementioned dynamic equilibrium, the conversion of the 3'-silyl isomer to the 2'-silyl isomer continues in the solution until almost all of it is converted to the 2'-silyl isomer and crystallizes, thereby completing this disclosure. To achieve the above objective, the organic solvent is a solvent in which the compound of formula (I) is slightly soluble at room temperature. In some embodiments, "slightly soluble" includes a solubility of 0.01 g to 1 g / L at 20°C and 1 atmosphere. In some embodiments, the organic solvent is selected from one or more of alcohols, esters, ethers, acids, ketones, nitrogen-containing heterocyclic compounds, and haloalkanes. In some embodiments, the organic solvent is selected from one or more of methanol, ethanol, acetone, pyridine, acetic acid, isopropyl ester, ethyl acetate, methyl tert-butyl ether, and / or dichloromethane. In some embodiments, the organic solvent is selected from one or more of methanol, ethanol, acetone, pyridine, acetic acid, and isopropyl ester. To achieve a cost balance between the completeness of the above conversion and the amount of solvent used, in some embodiments, the weight-to-volume ratio of the compound of formula (II) to the organic solvent is 1:1-20 kg / L. In some embodiments, the weight-to-volume ratio of the compound of formula (II) to the organic solvent is 1:2-6 kg / L.

[0032] Those skilled in the art are aware of various reaction conditions under which silane-based protecting groups migrate. Any reaction condition that allows the migration of silane-based protecting groups to occur upon contact between a mixture containing a compound of formula (II) and an organic solvent and an organic base can be used in this disclosure. In some embodiments, the conditions under which the silane migration reaction occurs include one or more of the following:

[0033] The reaction temperature is -10 to 35℃;

[0034] The reaction time is 4-36 hours;

[0035] The weight-to-volume ratio of the compound of formula (II) to the organic base is 1:0.1-1.2 kg / L.

[0036] In some embodiments, the conditions under which the silane migration reaction can occur include one or more of the following:

[0037] The reaction temperature is -5℃ to 30℃;

[0038] The reaction time is 10-14 hours;

[0039] The weight-to-volume ratio of the compound of formula (II) to the organic base is 1:0.4-0.6 kg / L.

[0040] In some embodiments, the conditions under which the silane migration reaction can occur also include carrying out the reaction under suitable pressure and atmosphere, such as atmospheric pressure or an air atmosphere.

[0041] The organic base serves to provide alkaline reaction conditions, promoting the breaking of the chemical bond between the silicon atom in the silane protecting group and the oxygen atom in the silane protecting group, thereby facilitating the silane migration reaction. In some embodiments, the organic base is selected from one or more of C3-C12 organic amine compounds and nitrogen-containing heterocyclic compounds. In some embodiments, the amine compound is at least one of trimethylamine, triethylamine, tripropylamine, diisopropylamine, N,N-diisopropylethylamine, or diisopropylamine; in some embodiments, the nitrogen-containing heterocyclic compound is selected from imidazole or pyridine. In some embodiments, the organic base is selected from one or more of diisopropylamine, pyridine, propylenediamine, or triethylamine.

[0042] In some embodiments, B is a nucleic acid base or a universal base group in which any amino group (if present) is protected; in some embodiments, B is selected from U, T, protected A, protected C, protected 5-methyl C, and protected G. "Universal base" refers to a base analog that can replace a nucleic acid base and pairs with all four standard bases. In some embodiments, the universal base is one of hypoxanthine bromouracil, 3-nitropyrrole, 5-nitroindole, or 7-azaindole.

[0043] In some embodiments, B is one of the following groups:

[0044]

[0045] Among them, R N It is an amino protecting group. In some embodiments, R N It is one of acetyl, propionyl, isobutyryl, benzoyl, Fmoc, or Boc protecting groups. In some embodiments, R N It is one of acetyl, isobutyryl, or benzoyl. In some embodiments, B is one of A (Bz), G (iBu), C (Ac), and U:

[0046]

[0047] Silyl protecting groups are commonly used in the field of nucleic acid pharmaceuticals. In some embodiments, the silyl protecting group is a substituted silyl group. In some embodiments, the silyl protecting group is a trialkyl-substituted silyl group. In some embodiments, the silyl protecting group is (R... a )3Si- or (R a )2SiR b - The groups shown, where each R a R b Each silane protecting group is independently hydrogen, a C1-C6 straight-chain or branched alkyl group, a phenyl group, or a substituted phenyl group, but not all of them are hydrogen. In some embodiments, the silane protecting group is selected from one of tert-butyldimethylsilane (TBDMS), tert-butyldiphenylsilane (TBDPS), triisopropylsilane (TIPS), trimethylsilane (TMS), triethylsilane (TES), and methyldiisopropylsilane (MDIPS).

[0048] Non-silane hydroxyl protecting groups are commonly used in the field of nucleic acid pharmaceuticals as 5'-hydroxyl protecting groups on ribose. In some embodiments, the non-silane hydroxyl protecting group is (R c The triarylmethyl group shown in 3C-, each R c The hydroxyl protecting group is independently selected from phenyl or substituted phenyl groups. In some embodiments, the non-silane hydroxyl protecting group is 4,4'-dimethoxytriphenylmethyl, triphenylmethyl, or 4-methoxytriphenyl, acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-nitrobenzyl, bis(2-acetoxyethoxy)methyl (ACE), benzoyl carbamate, chloroacetyl, tri... One of chloroacetyl, trifluoroacetyl, neopentanoyl, benzoyl, p-phenylbenzoyl, 9-fluorenylmethyl carbonate, methanesulfonate, toluenesulfonate, triphenylmethyl (triphenylmethyl), monomethoxytriphenylmethyl, dimethoxytriphenylmethyl (DMT), trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl (FPMP), 9-phenylxanthine-9-yl (Pixyl), and 9-(p-methoxyphenyl)xanthine-9-yl (MOX). In some embodiments, the non-silane hydroxyl protecting group is 4,4'-dimethoxytriphenylmethyl, triphenylmethyl, or 4-methoxytriphenyl.

[0049] R3, R4, R5, and R6 are each independently hydrogen or a C1-C4 alkyl group. Considering the balance between cost and synthesis efficiency, in some embodiments, R3, R4, R5, and R6 are each independently hydrogen, methyl, or ethyl. In some embodiments, R3, R4, R5, and R6 are all hydrogen.

[0050] In some embodiments, the compound of formula (II) is

[0051]

[0052] In some embodiments, the mixture further comprises a compound represented by formula (I):

[0053]

[0054] The definitions and selection ranges of R1-R6 and B are the same as those described above. In some embodiments, the compounds represented by formula (I) in the mixture contain the same R1-R6 and B as those represented by formula (II), the only difference being the connection position of the silane protecting group represented by R1.

[0055] In some embodiments, the weight ratio of compound (I) to compound (II) in the mixture is 1:1.2-2.0. In some embodiments, based on the total weight of compounds (I) and (II), the content of compound (I) is 15-40 wt.% and the content of compound (II) is 55%-85 wt.%. In some embodiments, the content of compound (I) is 20-35 wt.% and the content of compound (II) is 60%-80 wt.%. In some embodiments, compounds (I) and (II) in the mixture are obtained by silanization of the compound represented by formula (III).

[0056]

[0057] The definitions and selection ranges of R2-R6 and B are the same as those described above.

[0058] In some embodiments, the compound of formula (I) is

[0059] In some embodiments, the method further includes a solid-liquid separation step. In some embodiments, the solid-liquid separation may sequentially include the following steps: filtering the reaction mixture to separate the solid; rinsing the resulting solid with an organic solvent; drying to remove the solvent and collecting the solid. In some embodiments, the organic solvent used for rinsing is the same as the organic solvent in the mixture in which the silane migration reaction occurs. In some embodiments, the organic solvent used for rinsing is selected from one or more of methyl tert-butyl ether, methanol, ethanol, n-butanol, dichloromethane, and ethyl acetate. Various suitable filtration methods can be used in this disclosure. Examples of filtration methods in some embodiments include, but are not limited to, vacuum filtration and centrifugal filtration. In some embodiments, the solid-liquid separation is carried out at a temperature of -5°C to 35°C. In some embodiments, the rinsing is carried out at a temperature of -5°C to 5°C.

[0060] Example

[0061] The present disclosure and its beneficial effects will be described in detail below with reference to specific embodiments.

[0062] The sources of the reagents and instruments used in the following examples are shown in Table 1 below:

[0063] Table 1. Sources of Reagents and Instruments

[0064] Reagents / Instruments Model / Purity Manufacturer / Supplier Acetonitrile AR level Fuchen (Tianjin) Chemical Co., Ltd. dichloromethane AR level Fuchen (Tianjin) Chemical Co., Ltd. Isopropanol AR level Fuchen (Tianjin) Chemical Co., Ltd. diisopropylamine AR level Fuchen (Tianjin) Chemical Co., Ltd. Triethylamine AR level Fuchen (Tianjin) Chemical Co., Ltd. Low-temperature constant temperature cooling circulation pump DHJF-4005 Zhengzhou Great Wall Science & Industry Trade Co., Ltd. High-performance liquid chromatography (HPLC) LC-2050C 3D Shimadzu

[0065] Example 1

[0066] 200g of 5'-DMT-isobutyrylguanosine (a mixture of 2′- and 3′-tert-butyldimethylsilane protecting isomers) (HPLC analysis showed that the 2′-silyl isomer had a purity of 23wt%, the 3′-silyl isomer had a purity of 72wt%, and the remainder was impurities) was added to a reaction flask containing 800mL of a mixed solvent of acetone and ethanol (acetone to ethanol volume ratio of 1:1). At this point, the system was a yellow turbid liquid. While stirring at room temperature (25-30℃), 6g of... 0 mL of propylenediamine was stirred at room temperature (25℃-30℃) for 12 hours, resulting in the precipitation of a white solid. The entire system changed from yellow to off-white. The turbid liquid was vacuum filtered, and the filter cake was washed three times with a mixed solvent of acetone and ethanol (volume ratio 1:1) at 0℃, 50 mL each time. After filtration and drying, 153 g of solid was obtained, with a yield of 73.8 wt%. HPLC analysis showed that it contained 96.5 wt% of 2′-silyl isomer and only 0.5 wt% of 3′-silyl isomer.

[0067] Example 2

[0068] 200g of a mixture of 5'-DMT-uridine (a mixture of 2′- and 3′-tert-butyldimethylsilane protecting isomers) (HPLC analysis showed that the 2′-silyl isomer had a purity of 33wt%, the 3′-silyl isomer had a purity of 63wt%, and the remainder was impurities) was added to a reaction flask containing 800mL of methanol. The system dissolved and became clear. 80mL of triethylamine was then added under stirring at room temperature (25℃-30℃). After stirring for 12 hours at room temperature (25℃-30℃), a white solid precipitated. The solid was vacuum filtered, and the filter cake was washed three times with 50mL of methanol solution at 0℃. After filtration and drying, 166g of solid was obtained, with a yield of 80.9wt%. HPLC analysis showed that the solid contained 97.5wt% of the 2′-silyl isomer and only 0.4wt% of the 3′-silyl isomer.

[0069] Example 3

[0070] 200g of 5'-DMT-N6-Bz-adenosine (a mixture of 2'- and 3'-tert-butyldimethylsilane protecting isomers) (HPLC analysis showed that the 2'-silyl isomer had a purity of 27wt%, the 3'-silyl isomer had a purity of 65wt%, and the remainder was impurities) was added to a reaction flask containing 800mL of pyridine. The system was dissolved at room temperature (25℃-30℃) until clear. After stirring at room temperature (25℃-30℃) for 18 hours, a white solid precipitated. The solid was vacuum filtered, and the filter cake was washed three times with 50mL of pyridine at 0℃. After filtration and drying, 170g of solid was obtained, with a yield of 81.1%. The solid contained 95.5wt% of the 2'-silyl isomer and only 0.4wt% of the 3'-silyl isomer.

[0071] Example 4

[0072] 200g of 5'-DMT-acetylcytidine (a mixture of 2'- and 3'-tert-butyldimethylsilane protecting isomers) (HPLC analysis showed that the 2'-silyl isomer had a purity of 22wt%, the 3'-silyl isomer had a purity of 75wt%, and the remainder was impurities) was added to a reaction flask containing 800ml of a mixed solvent of acetic acid and isopropyl ester (acetic acid to isopropyl ester volume ratio of 1:1). The mixture dissolved, the system became clear, and the mixture was stirred at room temperature (25℃-30℃). Add 80 mL of diisopropylamine while stirring. After stirring at room temperature (25℃-30℃) for 12 hours, a white solid precipitates, and the entire system changes from yellow to off-white. Vacuum filter the turbid liquid and wash the filter cake three times with the aforementioned mixed solvent of acetic acid and isopropyl ester at 0℃, 50 mL each time. Filter, dry, scrape off the filter cake to obtain 182 g of filter cake, with a yield of 89.3%. It contains 98.2 wt% 2'-silicon isomer and only 0.1 wt% 3'-silicon isomer.

[0073] The results of the above embodiments demonstrate that, using the method of this disclosure, compounds of formula (II) in various mixtures containing different formula (II) compounds and organic solvents can be efficiently converted into compounds of formula (I), and the compounds of formula (I) can be obtained by solid-liquid separation with a yield of at least 73.8% and a purity of at least 95.5% for the product of formula (I) compounds. Furthermore, within a suitable range of organic base dosage, the method of this disclosure can achieve even higher conversion rates and higher product purity, with yields reaching up to 89.3%; purity of at least 97.5 wt%, and even up to 98.2 wt%; and low content of byproducts and impurities in the final product, with the content of the byproduct formula (II) compound controlled to below 0.5 wt%, and even as low as 0.1 wt%.

[0074] Comparative Example 1

[0075] 200 g of 5'-DMT-isobutyrylguanosine (a mixture of 2'- and 3'-tert-butyldimethylsilane protecting isomers) (HPLC analysis showed that the 2'-silyl isomer had a purity of 44 wt%, the 3'-silyl isomer had a purity of 52 wt%, and the remainder was impurities) was separated in 200 mL of dichloromethane solution. Column chromatography was performed using 1 kg of 100-200 mesh silica gel as the stationary phase, and the column was neutralized with 5 L of n-hexane containing 3‰ (v / v) triethylamine. Wet loading was used. The eluent was first eluted with pure dichloromethane until the 2'-tert-butyldimethylsilane protecting group isomer was obtained, then replaced with a mixed solvent of ethyl acetate:dichloromethane = 4:1 (v / v). The isomer composition in the eluent was monitored by TLC. Eluents containing the 2'-tert-butyldimethylsilane protecting group isomer, a mixture of 2'- and 3'-tert-butyldimethylsilane protecting group isomers, and a 3'-tert-butyldimethylsilane protecting group isomer were collected separately. The solvent in each eluent containing different isomers was evaporated to dryness and weighed, yielding 40 g of 2'-silyl isomer with a purity of 95%, 110 g of a mixture of 2'- and 3'-silyl isomers, and 45 g of 3'-silyl isomer with a purity of 95%. The yield of the 2'-silyl isomer was only 20%.

[0076] As the results above show, column chromatography alone is insufficient to efficiently and effectively obtain high-purity 2'-silicon isomers, and large mixtures of 2'- and 3'-silicon isomers are difficult to further separate. In contrast, the method of this invention can effectively obtain 2'-silicon isomers with high yield and purity, and low impurity content (such as 3'-silicon isomers), making it suitable for industrial production.

Claims

1. A method for preparing a compound, the method comprising contacting a mixture with an organic base under conditions conducive to silane migration, wherein, The mixture contains a compound of formula (II) and an organic solvent, wherein the organic solvent is a solvent in which the compound of formula (I) is slightly soluble at room temperature: R1 is a silyl protecting group; R2 is a non-silane hydroxyl protecting group; R3, R4, R5 and R6 are each independently one of hydrogen or a C1-C4 alkyl group; B is a group with a molecular weight between 50 and 420 that does not participate in silane migration reactions.

2. The method according to claim 1, wherein, The organic solvent is selected from one or more of alcohols, esters, ethers, acids, ketones, nitrogen-containing heterocyclic compounds, and haloalkanes; and / or The weight-to-volume ratio of the compound of formula (II) to the organic solvent is 1:1-20 kg / L.

3. The method according to claim 2, wherein, The organic solvent is selected from one or more of methanol, ethanol, acetone, pyridine, acetic acid, isopropyl ester, ethyl acetate, methyl tert-butyl ether, and / or dichloromethane; and / or The weight-to-volume ratio of the compound of formula (II) to the organic solvent is 1:2-6 kg / L.

4. The method according to claim 1, wherein, The conditions under which the silane migration reaction can occur include one or more of the following: The reaction temperature is -10 to 35℃; The reaction time is 4-36 hours; The weight-to-volume ratio of the compound of formula (II) to the organic base is 1:0.1-1.2 kg / L.

5. The method according to claim 4, wherein, The conditions under which the silane migration reaction can occur include one or more of the following: The reaction temperature is -5℃ to 35℃; The reaction time is 10-14 hours; The weight-to-volume ratio of the compound of formula (II) to the organic base is 1:0.4-0.6 kg / L.

6. The method according to any one of claims 1-5, wherein, The organic base is selected from one or more of C3-C12 organic amine compounds and nitrogen-containing heterocyclic compounds; Alternatively, the organic base may be one or more of trimethylamine, triethylamine, tripropylamine, diisopropylamine, N,N-diisopropylethylamine, diisopropylamine, imidazole, or pyridine; Alternatively, the organic base may be selected from one or more of diisopropylamine, pyridine, propylenediamine, or triethylamine.

7. The method according to any one of claims 1-5, wherein, B represents any amino group that is protected as a nucleic acid base or a universal base group.

8. The method according to claim 7, wherein, B is selected from one of U, T, protected A, protected C, protected 5-methyl C, and protected G.

9. The method according to claim 7, wherein, B is one of the following groups: Among them, R N It is an amino protecting group.

10. The method according to claim 9, wherein, The compound of formula (II) is 5'-DMT-isobutyrylguanosine protected by 2'-tert-butyldimethylsilane.

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