C6 '-site modified locked nucleoside compound and application thereof

Abstract

The invention provides a C6 '-site modified locked nucleoside compound and an application of the C6'-site modified locked nucleoside compound in synthesis of CN-LNA. In the prior art, 6 '-cyano locked nucleic acid (CN-LNA) has the defects of low double bond migration conversion rate, unstable reaction, difficulty in monitoring and unsuitability for future commercial production routes in cyano construction. The novel intermediate compound is adopted for preparing the C6 '-site modified locked nucleoside compound, the reaction route is shortened, meanwhile, the reaction condition is milder, the selectivity is high, the yield is high, operation is easy and convenient, the cost for synthesizing 6'-cyano locked nucleic acid (CN-LNA) is reduced, and good application prospects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of nucleotide chemical synthesis, specifically relating to C6'-modified nucleoside compounds and their applications. Technical Background

[0002] The application and development of oligonucleotides in various fields have demonstrated their high efficacy in disease treatment. However, due to problems such as poor in vivo stability, inadequate target cell uptake, and off-target effects including immune stimulation, the translation of oligonucleotides from the laboratory to the clinical setting faces significant challenges. Therefore, it has been recognized that the natural DNA and RNA structures must be chemically modified to make them suitable for therapeutic applications. Introducing chemical modifications enhances the stability of oligonucleotides, increases their affinity for targets, promotes cellular uptake, and improves their in vivo bioavailability.

[0003] Chemical modifications of nucleic acids can be divided into three categories: (1) modification of internucleotide bonds; (2) modification of sugar rings; and (3) modification of bases. Among them, modification of sugar rings will significantly affect the conformation of sugars, and this conformational change will determine the binding affinity of oligonucleotides to their complementary strands and double-stranded structures.

[0004] Locked nucleosides (LNAs), as RNA modifiers, form covalent bonds between the 2'-OH and 4'-C atoms of the sugar ring via methylene bridges. This significantly enhances their binding affinity to targets. Among all chemical modifications, LNAs exhibit the best double-strand stability, thus playing a prominent role in the application of oligonucleotide drugs. The strong binding properties of LNAs make them crucial in the field of miRNA applications. For example, when LNAs are used in antisense nucleic acids with "gapmer" structures, they can reduce chain length. Furthermore, LNAs can improve resistance to siRNAs and reduce the immunostimulatory response to siRNAs.

[0005] Chinese scientists have made cutting-edge progress in the field of the impact of chemically modified ASO interactions with intracellular proteins on ASO drug toxicity. They have independently developed a new generation of hydrophilic 6'-cyano-locked nucleic acid (CN-LNA) structure based on locked nucleic acids (LNA) (publication number: CN116606338A). Evaluation results show that compared to LNA, S-CN-LNA modification is safer, significantly reducing the affinity of PS-ASO for binding to intracellular proteins, thereby reducing the impact on the normal function of intracellular proteins, decreasing cytotoxicity, and improving therapeutic efficacy. Simultaneously, S-CN-LNA exhibits high nuclease tolerance, significantly superior to LNA in this aspect. Furthermore, S-CN-LNA also demonstrates good target gene affinity, with a ΔTm / mod of 4.2℃ per modification, lower than LNA, which is more conducive to the catalytic cleavage efficiency of RNase H enzyme. Based on this structure, a novel stereoselective synthesis method was originally constructed (publication number: CN116789725A), and small-scale laboratory synthesis of four base phosphoramid monomers (A, G, mC, and T) in both R / S configurations was achieved, verifying the feasibility of the synthetic route.

[0006] The existing synthesis steps for S-6'-CN-LNA are as follows:

[0007]

[0008] The steps involving the conversion of compounds 6 to 10 into cyano groups after double bond migration, dihydroxylation, and oxidative cleavage, respectively, present the following problems:

[0009] 1. Intermediates in double bond migration reactions are difficult to detect using conventional methods, making it impossible to control the reaction and adjust reaction conditions in a timely manner.

[0010] 2. The low conversion rate and poor stability in the double bond migration step greatly increase the complexity and uncertainty of the experiment.

[0011] 3. In the oxidative pyrolysis step, the dihydroxy compound raw material is difficult to react completely, resulting in numerous byproducts, which increases the difficulty of purification and affects the purity of the target product.

[0012] 4. The process of converting carbonyl compounds into cyano compounds has low yield, cumbersome post-processing, complex operation, and is not environmentally friendly.

[0013] 5. The experimental steps are numerous, and a large amount of raw materials are not fully utilized, which does not conform to the concept of green chemistry. Summary of the Invention

[0014] To address the shortcomings of existing CN-LNA synthesis techniques, such as low double bond migration conversion, reaction instability, and difficulty in monitoring during cyano group construction, this invention provides a C6'-modified locked nucleoside intermediate compound and its application in the synthesis of CN-LNA, facilitating the commercial production of cyano-locked nucleic acids. The intermediate of this invention offers advantages such as product stability, ease of detection, and ease of separation, resulting in a reaction route with high selectivity, high yield, stable reaction, simple operation, and reduced costs, making it a promising candidate for application. To achieve the above objectives, this invention employs the following technical solution:

[0015] This invention first provides a method for preparing a compound of formula IV, comprising the following steps: oxidizing a compound of formula III with an oxidizing agent, followed by dehydration of the oxidation product to obtain a compound of formula IV. The synthetic route is as follows:

[0016]

[0017] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0018] In addition, the present invention also provides a method for preparing a compound of formula III, comprising the following steps: condensing a compound of formula II in the presence of a nitrogen source, a base, and a condensing agent to obtain formula III, the synthetic route of which is as follows:

[0019]

[0020] The definitions of R1, R2, and B are the same as above.

[0021] This invention also provides a method for preparing a compound of formula II, comprising the following steps: oxidizing a compound of formula I in the presence of an oxidizing agent to generate a compound of formula II, the synthetic route of which is as follows:

[0022]

[0023] The definitions of R1, R2, and B are the same as above.

[0024] This invention also provides a method for preparing a compound of formula IV-1, comprising the following steps: Formula III-1 is oxidized and dehydrated to obtain a compound of formula IV-1, and the synthetic route is as follows:

[0025]

[0026] The definitions of R1, R2, and B are the same as above.

[0027] This invention also provides a method for preparing a compound of formula IV-2, comprising the following steps: Formula III-2 is oxidized and dehydrated to obtain compound IV-2, and the synthetic route is as follows:

[0028]

[0029] The definitions of R1, R2, and B are the same as above.

[0030] This invention also provides a method for preparing a compound of formula III-1, comprising the following steps: condensing a compound of formula II-1 in the presence of a nitrogen source, a base, and a condensing agent to obtain a compound of formula III-1, the synthetic route of which is as follows:

[0031]

[0032] The definitions of R1, R2, and B are the same as above.

[0033] This invention also provides a method for preparing a compound of formula III-2, comprising the following steps: condensing a compound of formula II-2 in the presence of a nitrogen source, a base, and a condensing agent to obtain a compound of formula III-2, the synthetic route of which is as follows:

[0034]

[0035] The definitions of R1, R2, and B are the same as above.

[0036] This invention also provides a method for preparing a compound of formula II-1, comprising the following steps: oxidizing a compound of formula I-1 in the presence of an oxidizing agent to generate a compound of formula II-1, the synthetic route of which is as follows:

[0037]

[0038] The definitions of R1, R2, and B are the same as above.

[0039] This invention also provides a method for preparing a compound of formula II-2, comprising the following steps: oxidizing a compound of formula I-2 in the presence of an oxidizing agent to generate a compound of formula II-2, the synthetic route of which is as follows:

[0040]

[0041] The definitions of R1, R2, and B are the same as above.

[0042] The present invention also provides a compound of formula III, the structure of which is shown below: The definitions of R1, R2, and B are the same as above.

[0043] Preferably, Formula III is Formula III-1 The definitions of R1, R2, and B are the same as above.

[0044] Preferably, Formula III is Formula III-2 The definitions of R1, R2, and B are the same as above.

[0045] Finally, the present invention also provides a compound of formula II, the structure of which is shown below: The definitions of R1, R2, and B are the same as above.

[0046] Preferably, formula II is formula II-1. The definitions of R1, R2, and B are the same as above.

[0047] Preferably, formula II is formula II-2. The definitions of R1, R2, and B are the same as above.

[0048] The beneficial effects of this invention are:

[0049] 1. This invention uses a novel intermediate formula III to synthesize S-6'-cyano-locked nucleic acid, or stereoisomerically selectively synthesizes R-6'-cyano-locked nucleic acid using formula III, overcoming the disadvantages of low yield and harsh operating conditions in the prior art.

[0050] 2. The present invention uses compounds of formula II or their stereoisomers to synthesize corresponding compounds of formula III or their stereoisomers, without the need for the oxidation of dihydroxy compounds using existing technologies, which produces isomerization products and intermediate compounds that are difficult to detect.

[0051] 3. The present invention uses compounds of formula I or their stereoisomers to synthesize corresponding compounds of formula II or their stereoisomers, without having to consider the problems of difficult double bond migration and difficult detection of intermediates in the prior art.

[0052] 4. The synthesis of 6'-cyano-locked nucleic acid (CN-LNA) using the intermediate of the present invention shortens the reaction route, improves the reaction yield, and overcomes the problem of difficult operation of reaction conditions in the prior art. Attached Figure Description

[0053] Figure 1 Example 1: High-performance liquid chromatography (HPLC) chromatogram of carboxylic acid-modified nucleoside compound 2, the product of step one in Example 1.

[0054] Figure 2 Example 1: High-performance liquid chromatography (HPLC) chromatogram of amide-modified nucleoside compound 3, the product of step two.

[0055] Figure 3 Example 1: High-performance liquid chromatography (HPLC) chromatogram of cyano-modified nucleoside compound 4, the product of step three.

[0056] Figure 4 The 1H NMR spectrum of cyano-modified nucleoside compound 4, the product of Example 1. Detailed Implementation

[0057] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. 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 only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising of," etc., will be understood to include the stated components or steps, without excluding other substances or steps.

[0058] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In some embodiments, materials, methods, and means well-known to those skilled in the art are not described in detail in order to highlight the spirit of the invention.

[0059] Unless otherwise specified, experimental methods in the following embodiments should be based on the guidelines provided in this invention, or by following experimental manuals or conventional conditions, other known experimental methods in the art, or the conditions recommended by the manufacturer. In the specific embodiments below, the measurement parameters of raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. For temperature and time parameters, acceptable deviations due to instrument testing accuracy or operational precision are permissible. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the reagents and materials used in the following embodiments are commercially available.

[0060] In the following examples, HATU is N,N,N′,N′-tetramethyl-O-(7-azabenzotriazol-1-yl)hexafluorophosphate, EDCI is N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, IBX is 2-iodobenzoic acid, and iBu is isobutyryl.

[0061] Specifically, the present invention provides a method for preparing a compound of formula IV, comprising the following steps: oxidizing a compound of formula III with an oxidant, followed by dehydration of the oxidation product to obtain the compound of formula IV, the synthetic route of which is as follows:

[0062]

[0063] Wherein, R1 and R2 are independently selected from H or hydroxyl protecting groups; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [ [(triisopropylsilyl)oxy]methyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0064] The oxidant is IBX or Dysmart oxidant; the reaction is carried out in an organic solvent, which is one of toluene, methanol, acetonitrile, and DMF, preferably acetonitrile; the oxidation reaction temperature is 40–100°C, preferably 60–90°C; the molar ratio of the compound of formula III-1, the oxidant, and the phase transfer catalyst is 1:1.0–5.0:1.0–5.0, preferably 1:2.0–3.0:2.0–3.0.

[0065] The novel intermediate formula III of this invention improves the yield of the compound of formula IV and reduces the reaction requirements.

[0066] In addition, the present invention also provides a method for preparing a compound of formula III, comprising the following steps: condensing a compound of formula II in the presence of a nitrogen source, a base, and a condensing agent to obtain formula III, the synthetic route of which is as follows:

[0067]

[0068] Wherein, R1 and R2 are independently selected from H or hydroxyl protecting groups; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [ [(triisopropylsilyl)oxy]methyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0069] In the ammonium condensation reaction, the base is one of triethylamine, N,N-diisopropylethylamine, pyridine, and potassium carbonate, preferably N,N-diisopropylethylamine; the reaction is carried out in the presence of a condensing agent, which is one or more of HATU and EDCI; the nitrogen source is ammonium chloride or ammonia; the molar ratio of the compound of formula II-1, the condensing agent, the base, and the nitrogen source is 1:1.0~2.0:1.5~5.0:5.0~15.0, preferably 1:1.2~1.8:2.0~4.0:8.0~12.0.

[0070] The synthesis of compound III using compound II is simple and yields a high reaction rate.

[0071] This invention also provides a method for preparing a compound of formula II, comprising the following steps: oxidizing a compound of formula I in the presence of an oxidizing agent to generate a compound of formula II, the synthetic route of which is as follows:

[0072]

[0073] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0074] The oxidant is sodium periodate; the catalyst is one or more of ruthenium trichloride, ruthenium trichloride hydrate, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium dichloride, and cis-bis(2,2-dipyridine)ruthenium dichloride; the oxidation reaction is carried out in a mixed solvent, which is a mixed solvent composed of dimethyl sulfoxide and water, methanol and water, acetonitrile and water, or 1,4-dioxane and water, preferably acetonitrile and water; the reaction temperature is room temperature; the molar ratio of Formula I-1, oxidant, and catalyst is 1:2 to 8:0.01 to 0.2, preferably 1:3.0 to 5.0:0.05 to 0.15.

[0075] This invention uses compounds of formula I to synthesize compounds of formula II, overcoming the cumbersome steps of existing technologies such as double bond migration followed by oxidation to dihydroxyl groups. This greatly simplifies the reaction conditions, improves the ease of operation, and significantly enhances selectivity and yield.

[0076] Preferably, the present invention also provides a method for preparing a compound of formula IV, comprising the following steps:

[0077] 1) Compound I is oxidized in the presence of an oxidizing agent to form compound II;

[0078] 2) Compound II is condensed in the presence of a nitrogen source, a base, and a condensing agent to obtain compound III;

[0079] 3) Compound III is oxidized with an oxidizing agent, and the oxidation product is then dehydrated to prepare compound IV.

[0080] Its synthetic route is as follows:

[0081]

[0082] Wherein, R1 and R2 are independently selected from H or hydroxyl protecting groups; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [ [(triisopropylsilyl)oxy]methyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0083] The reaction steps of formulas II, III and IV are as described above.

[0084] The route for synthesizing Formula IV using compounds of Formula II and Formula III overcomes the shortcomings of existing technologies in the preparation of Formula IV, such as low yield and poor stability of double bond migration reactions, which greatly increases the complexity and uncertainty of the experiment; in the oxidative cleavage step, the dihydroxy compound raw material is difficult to react completely, resulting in numerous byproducts, which increases the difficulty of purification and affects the purity of the target product; in the step of converting carbonyl compounds to cyano groups, the yield is low, the post-processing is cumbersome, the operation is complicated, and it is not environmentally friendly. This invention reduces the number of reaction steps, improves the reaction yield, and reduces the reaction cost.

[0085] This invention provides a method for preparing a compound of formula IV-1, comprising the following steps: oxidation and dehydration of a compound of formula III-1 to obtain a compound of formula IV-1, the synthetic route of which is as follows:

[0086]

[0087] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0088] In the preparation method of the above-mentioned compound IV-1, the oxidant is IBX or Dysmart oxidant; the reaction is carried out in an organic solvent, which is one of toluene, methanol, acetonitrile and DMF, preferably acetonitrile; the temperature of the oxidation reaction is 40-100℃, preferably 60-90℃; the molar ratio of the compound III-1, the oxidant and the phase transfer catalyst is 1:1.0-5.0:1.0-5.0, preferably 1:2.0-3.0:2.0-3.0.

[0089] This invention provides a method for preparing a compound of formula IV-2, comprising the following steps: oxidizing a compound of formula III-2 with an oxidizing agent, and then dehydrating the oxidation product to obtain a compound of formula IV-2. The synthetic route is as follows:

[0090]

[0091] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0092] In the preparation method of the above-mentioned compound IV-2, the oxidant is IBX or Dysmart oxidant; the reaction is carried out in an organic solvent, which is one of toluene, methanol, acetonitrile and DMF, preferably acetonitrile; the temperature of the oxidation reaction is 40-100℃, preferably 60-90℃; the molar ratio of the compound III-2, the oxidant and the phase transfer catalyst is 1:1.0-5.0:1.0-5.0, preferably 1:2.0-3.0:2.0-3.0.

[0093] This invention also provides a method for preparing a compound of formula III-1, comprising the following steps: condensing a compound of formula II-1 in the presence of a nitrogen source, a base, and a condensing agent to obtain a compound of formula III-1, the synthetic route of which is as follows:

[0094]

[0095] Wherein, R1 and R2 are independently selected from H or hydroxyl protecting groups; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [ [(triisopropylsilyl)oxy]methyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0096] In the preparation method of the above-mentioned compound III-1, the base in the ammonium condensation reaction is one of triethylamine, N,N-diisopropylethylamine, pyridine, and potassium carbonate, preferably N,N-diisopropylethylamine and triethylamine; the reaction is carried out in the presence of a condensing agent, which is one or more of HATU and EDCI; the nitrogen source is ammonium chloride or ammonia; the molar ratio of the compound II-1, the condensing agent, the base, and the nitrogen source is 1:1.0~2.0:1.5~5.0:5.0~15.0, preferably 1:1.2~1.8:2.0~4.0:8.0~12.0.

[0097] This invention also provides a method for preparing a compound of formula III-2, comprising the following steps: condensing a compound of formula II-2 in the presence of a nitrogen source, a base, and a condensing agent to obtain a compound of formula III-2, the synthetic route of which is as follows:

[0098]

[0099] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0100] In the preparation method of the above-mentioned compound III-2, the base in the ammonium condensation reaction is one of triethylamine, N,N-diisopropylethylamine, pyridine, and potassium carbonate, preferably N,N-diisopropylethylamine and triethylamine; the reaction is carried out in the presence of a condensing agent, which is one or more of HATU and EDCI; the nitrogen source is ammonium chloride or ammonia; the molar ratio of the compound II-2, the condensing agent, the base, and the nitrogen source is 1:1.0~2.0:1.5~5.0:5.0~15.0, preferably 1:1.2~1.8:2.0~4.0:8.0~12.0.

[0101] This invention also provides a method for preparing a compound of formula II-1, comprising the following steps: reacting a compound of formula I-1 under the oxidation of an oxidant to generate a compound of formula II-1, the synthetic route of which is as follows:

[0102]

[0103] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0104] In the preparation method of the above-mentioned compound II-1, the oxidant is sodium periodate; the catalyst is one or more of ruthenium trichloride, ruthenium trichloride hydrate, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium dichloride, and cis-bis(2,2-dipyridine)ruthenium dichloride; the oxidation reaction is carried out in a mixed solvent, which is a mixed solvent composed of dimethyl sulfoxide and water, methanol and water, acetonitrile and water, or 1,4-dioxane and water, preferably acetonitrile and water; the reaction temperature is room temperature; the molar ratio of the compound I-1, the oxidant, and the catalyst is 1:2.0~8.0:0.01~0.2, preferably 1:3.0~5.0:0.05~0.15.

[0105] This invention also provides a method for preparing a compound of formula II-2, comprising the following steps: reacting a compound of formula I-2 under the oxidation of an oxidant to generate a compound of formula II-2, the synthetic route of which is as follows:

[0106]

[0107] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0108] In the preparation method of the above-mentioned compound II-2, the oxidant is sodium periodate; the catalyst is one or more of ruthenium trichloride, ruthenium trichloride hydrate, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium dichloride, and cis-bis(2,2-dipyridine)ruthenium dichloride; the oxidation reaction is carried out in a mixed solvent, which is a mixed solvent composed of dimethyl sulfoxide and water, methanol and water, acetonitrile and water, or 1,4-dioxane and water, preferably acetonitrile and water; the reaction temperature is room temperature; the molar ratio of the compound I-2, the oxidant, and the catalyst is 1:2.0~8.0:0.01~0.2, preferably 1:3.0~5.0:0.05~0.15.

[0109] The present invention also provides a method for preparing a compound of formula IV-1, comprising the following steps:

[0110] 1) The compound of formula I-1 is oxidized by an oxidizing agent to produce the compound shown in formula II-1;

[0111] 2) Compound II-1 is condensed in the presence of a nitrogen source, a base and a condensing agent to obtain compound III-1;

[0112] 3) Compound IV-1 was prepared by oxidation and dehydration of formula III-1;

[0113] Its synthetic route is as follows:

[0114]

[0115] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0116] The preparation conditions for Formula II-1, Formula III-1 and Formula IV-1 are the same as those described above.

[0117] The present invention also provides a method for preparing a compound of formula IV-2, comprising the following steps,

[0118] 1) The compound of formula I-2 is oxidized by an oxidizing agent to produce the compound shown in formula II-2;

[0119] 2) Compound II-2 is condensed in the presence of a nitrogen source, a base and a condensing agent to obtain compound III-2;

[0120] 3) Compound IV-2 was prepared by oxidation and dehydration of formula III-2.

[0121] Its synthetic route is as follows:

[0122]

[0123] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0124] The preparation conditions for Formula II-2, Formula III-2 and Formula IV-2 are the same as those described above.

[0125] The present invention also provides a compound of formula III, the structure of which is shown below:

[0126] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0127] Preferably, Equation III is Equation III-1

[0128] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0129] Preferably, Equation III is Equation III-2

[0130] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0131] Finally, the present invention also provides a compound of formula II, the structure of which is shown below:

[0132] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0133] Preferably, formula II is formula II-1.

[0134] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0135] Preferably, formula II is formula II-2.

[0136] Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

[0137] The technical solutions of this disclosure will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of this disclosure and should not be construed as limiting the scope of protection of this disclosure. All technologies implemented based on the above content of this disclosure are covered within the scope of protection intended by this disclosure.

[0138] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0139] Example 1: Preparation of cyano-locked nucleoside compound 4

[0140] The reaction equation is as follows:

[0141]

[0142] Step 1: Synthesis of Compound 2

[0143] First, prepare a mixed solvent of acetonitrile and water at a volume ratio of 3:1. Dissolve 100 g (143.28 mmol) of terminal olefin compound 1 in 800 mL of the acetonitrile and water mixture. While stirring, add 2.97 g (14.33 mmol, 0.1 eq) of ruthenium trichloride. After the addition is complete, cool to 10 °C. Add sodium periodate (122.59 g, 573.14 mmol, 4.0 eq) in portions to the cooled system. After the addition is complete, maintain the temperature and stir for 10 minutes. After stirring at room temperature for 15 hours, HPLC analysis shows that the remaining reactant 1 is <2%, at which point the reaction is stopped. Filter through a 30 g diatomaceous earth liner, and wash the filter cake three times with 20 mL of acetonitrile each time. Collect the filtrate and extract the reaction solution with ethyl acetate (2 × 500 mL). Wash the organic phase once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 91.02 g of crude product of carboxylic acid compound 2, which is yellow and solid, with a yield of 88.74% and an HPLC purity of 91.30%. 1 H NMR(400MHz, CDCl3)δ8.45(s,1H),8.17(s,1H),7.93–7.71(m,4H),7.69–7. 65(m,5H),7.50–7.35(m,8H),7.23(s,2H),6.51(d,J=7.0Hz,1H),5.22(t,J =7.0Hz,1H),4.82(d,J=12.3Hz,1H),4.62–4.48(m,2H),4.06–3.92(m,2H), 3.71(d,J=12.5Hz,1H),2.79–2.74(m,1H),2.62–2.57(m,1H),1.06(s,9H).

[0144] Step 2: Synthesis of Compound 3

[0145] The carboxylic acid-substituted nucleoside product 2 obtained in step one was added to 360 mL of dry DMF. While stirring, HATU (72.52 g, 190.72 mmol, 1.5 eq), N,N-diisopropylethylamine (66.44 mL, 381.43 mmol, 3.0 eq), and ammonium chloride (68.01 g, 1.27 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that starting material 2 remained at <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 84.52 g of crude yellow oily amide compound 3, with a yield of 92.99% and a purity of 89.29%. 1 H NMR (400MHz, CDCl3) δ8.52(s,1H),8.17(s,1H),7.93(d,J=1.6Hz,1H),7.86–7.83(m,1H) ,7.77–7.75(m,1H),7.69–7.61(m,5H),7.53–7.35(m,9H),7.23(s,2H),6.58(d,J=7.0Hz ,1H),5.91(s,2H),5.32(t,J=7.0Hz,1H),4.74–4.58(m,2H),4.21(t,J=7.0Hz,1H),4.06 –3.92(m,2H),3.71(d,J=12.5Hz,1H),2.92–2.87(m,1H),2.55–2.50(m,1H),1.06(s,9H).

[0146] Step 3: Synthesis of Compound 4

[0147] Under nitrogen protection, IBX (82.76 g, 295.57 mmol, 2.5 eq) was added to 510 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (42.89 g, 295.57 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 3 (84.52 g, 118.23 mmol) obtained in step two was added, and the mixture was heated to 80 °C for 2 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. 500 mL of ethyl acetate and 300 mL of water were added to extract the reaction mixture, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 4 hours, filter and dry the filter cake to obtain 74.93 g of white solid 6'-cyano-locked nucleoside compound 4, with a yield of 92.81% and a purity of 97.04%. 1 H NMR (400MHz, CDCl3) δ8.21(s,1H),7.82–7.73(m,3H),7.72–7.65(m,6H),7.49–7.32(m,9H),5.97(s,1H),5.86(s ,2H),5.18(s,1H),,4.89–4.77(m,3H),4.34(s,1H),4.31(d,J=16.0Hz,1H),4.17(d,J=16.0Hz,1H),1.06(s,9H).

[0148] Example 2: Preparation of cyano-locked nucleoside compound 8

[0149] The reaction equation is as follows:

[0150]

[0151] Step 1: Synthesis of Compound 6

[0152] The terminal olefin compound 5 (100 g, 143.28 mmol) was dissolved in 800 mL of a mixed solvent of acetonitrile and water. Ruthenium trichloride (2.84 g, 13.70 mmol, 0.1 eq) was added with stirring. After the addition was complete, the mixture was cooled to 10 °C. Sodium periodate (117.21 g, 547.98 mmol, 4.0 eq) was added in portions to the cooled mixture. After the addition was complete, the mixture was stirred at room temperature for 10 minutes. After stirring at room temperature for 15 hours, the reaction was monitored by HPLC. Since the remaining reactant 5 was <2%, the reaction was stopped. The mixture was filtered through a 30 g diatomaceous earth filter, and the filter cake was washed three times with 20 mL of acetonitrile each time. The filtrate was collected and extracted with ethyl acetate (2 × 500 mL). The organic phase was washed once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 93.63 g of crude yellow solid carboxylic acid compound 6, with a yield of 91.38% and an HPLC purity of 88.25%. This crude product was used directly in the next step without further purification.

[0153] Step 2: Synthesis of Compound 7

[0154] The carboxylic acid-substituted nucleoside product 6 obtained in step one was added to 380 mL of dry DMF. While stirring, HATU (71.40 g, 187.78 mmol, 1.5 eq), N,N-diisopropylethylamine (65.42 mL, 375.56 mmol, 3.0 eq), and ammonium chloride (66.96 g, 1.25 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that starting material 6 remained at <2%, and the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 90.28 g of crude yellow oily amide compound 7, with a yield of 96.55% and a purity of 87.13%. This product was directly added to the next step without further purification.

[0155] Step 3: Synthesis of Compound 8

[0156] Under nitrogen protection, IBX (84.61 g, 302.17 mmol, 2.5 eq) was added to 540 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (43.84 g, 302.17 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 7 (90.28 g, 120.87 mmol) obtained in step two was added, and the mixture was heated to 80 °C for 4 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. 500 mL of ethyl acetate and 300 mL of water were added to extract the reaction mixture, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 6 hours, filter and dry the filter cake to obtain 75.47 g of white solid 6'-cyano-locked nucleoside compound 8, with a yield of 87.34% and a purity of 96.32%. 1 H NMR (400MHz, CDCl3) δ7.82-7.76(m,3H),7.71-7.16(m,6H),7.51-7.30(m,9H),6.10(s,1H),4.95(s,1H),4.92(s,1H),4. 77(s,2H),4.73(d,J=2.7Hz,2H),4.50(s,1H),4.14(d,J=12.0Hz,1H),4.07(s,3H),4.02(d,J=12.0Hz,1H),1.10(s,9H).

[0157] Example 3: Preparation of cyano-locked nucleoside compound 12

[0158] The reaction equation is as follows:

[0159]

[0160] Step 1: Synthesis of Compound 10

[0161] The terminal olefin compound 9 (100 g, 145.37 mmol) was dissolved in 800 mL of a mixed solvent of acetonitrile and water. Ruthenium trichloride (3.32 g, 15.99 mmol, 0.11 eq) was added with stirring. After the addition was complete, the mixture was cooled to 10 °C. Sodium periodate (124.37 g, 581.47 mmol, 4.0 eq) was added in portions to the cooled mixture. After the addition was complete, the mixture was stirred at room temperature for 10 minutes. The mixture was then transferred to room temperature and stirred for 22 h. HPLC analysis showed that starting material 9 remained at <2%, at which point the reaction was stopped. The mixture was filtered through a 30 g diatomaceous earth filter, and the filter cake was washed three times with 20 mL of acetonitrile each time. The filtrate was collected, and the reaction mixture was extracted with ethyl acetate (2 × 500 mL). The organic phase was washed once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 100.83 g of crude product of carboxylic acid compound 10, which is yellow and solid, with a yield of 98.26% and an HPLC purity of 87.93%. It was directly used in the next step without further purification.

[0162] Step 2: Synthesis of Compound 11

[0163] The carboxylic acid-substituted nucleoside product 10 obtained in step one was added to 400 mL of dry DMF. While stirring, EDCI (41.07 g, 214.26 mmol, 1.5 eq), N,N-diisopropylethylamine (74.64 mL, 428.53 mmol, 3.0 eq), and ammonium chloride (76.40 g, 1.43 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 4 hours. HPLC analysis showed that the remaining reactant 10 was <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 88.90 g of crude yellow oily amide compound 11, with a yield of 88.29% and a purity of 90.29%. This crude product was directly added to the next step without further purification.

[0164] Step 3: Synthesis of Compound 12

[0165] Under nitrogen protection, IBX (88.29 g, 315.29 mmol, 2.5 eq) was added to 540 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (45.75 g, 315.29 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 11 (88.90 g, 126.12 mmol) obtained in step two was added, and the mixture was heated to 85 °C for 3 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. 500 mL of ethyl acetate and 300 mL of water were added to extract the reaction mixture, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to 0 °C and crystallize for 6 hours, filter and dry the filter cake to obtain 77.25 g of white solid 6'-cyano-locked nucleoside compound 12, with a yield of 91.03% and a purity of 98.21%.

[0166] Example 4: Preparation of cyano-locked nucleoside compound 16

[0167] The reaction equation is as follows:

[0168]

[0169] Step 1: Synthesis of Compound 14

[0170] Terminal olefin compound 13 (100 g, 145.16 mmol) was dissolved in 800 mL of a mixed solvent of acetonitrile and water. Ruthenium trichloride (3.01 g, 14.52 mmol, 0.10 eq) was added with stirring. After the addition was complete, the mixture was cooled to 10 °C. Sodium periodate (124.19 g, 580.64 mmol, 4.0 eq) was added in portions to the cooled mixture. After the addition was complete, the mixture was stirred at room temperature for 10 minutes. The mixture was then transferred to room temperature and stirred for 15 h. HPLC analysis showed that starting material 13 remained at <2%, at which point the reaction was stopped. The mixture was filtered through a 30 g diatomaceous earth filter, and the filter cake was washed three times with 20 mL of acetonitrile each time. The filtrate was collected, and the reaction mixture was extracted with ethyl acetate (2 × 500 mL). The organic phase was washed once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 94.26 g of crude product of carboxylic acid compound 14, which is a yellow solid, with a yield of 91.86% and an HPLC purity of 90.62%. It was directly fed into the next step without further purification.

[0171] Step 2: Synthesis of Compound 15

[0172] The carboxylic acid-substituted nucleoside product 14 obtained in step one was added to 380 mL of dry DMF. While stirring, EDCI (40.90 g, 213.36 mmol, 1.6 eq), N,N-diisopropylethylamine (69.68 mL, 400.05 mmol, 3.0 eq), and ammonium chloride (71.33 g, 1.33 mol, 10.0 eq) were added, and the mixture was heated to 35 °C for 2 hours. HPLC analysis showed that starting material 14 remained at <2%, and the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 87.93 g of crude yellow oily amide compound 15, with a yield of 93.41% and a purity of 92.24%. This crude product was directly added to the next step without further purification.

[0173] Step 3: Synthesis of Compound 16

[0174] Under nitrogen protection, IBX (87.20 g, 311.42 mmol, 2.5 eq) was added to 540 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (45.19 g, 311.42 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 15 (87.93 g, 124.57 mmol) obtained in step two was added, and the mixture was heated to 80 °C for 4 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. 500 mL of ethyl acetate and 300 mL of water were added to extract the reaction mixture, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 6 hours, filter and dry the filter cake to obtain 76.29 g of white solid 6'-cyano-locked nucleoside compound 16, with a yield of 90.89% and a purity of 99.34%. 1H NMR(400MHz, CDCl3)δ8.99(s,1H),7.85-7.76(m,3H),7.68-7.64(m,5H),7.52-7.42(m,5H),7.38-7.33(m,5H),5.84(s,1H),4.87(s,1H),4. 83(s,1H),4.82(d,J=6.6Hz,1H),4.71(d,J=6.6Hz,1H),4.24(s,1H),4.17(d,J=6.9Hz,1H),4.01(d,J=6.9Hz,1H),1.63(s,3H),1.10(s,9H).

[0175] Example 5: Preparation of cyano-locked nucleoside compound 20

[0176] The reaction equation is as follows:

[0177]

[0178] Step 1: Synthesis of Compound 18

[0179] Terminal olefin compound 18 (100 g, 148.18 mmol) was dissolved in 800 mL of a mixed solvent of acetonitrile and water. Ruthenium trichloride (3.07 g, 14.82 mmol, 0.10 eq) was added with stirring. After the addition was complete, the mixture was cooled to 10 °C. Sodium periodate (110.93 g, 518.62 mmol, 3.5 eq) was added in portions to the cooled mixture. After the addition was complete, the mixture was stirred at room temperature for 10 minutes. The mixture was then transferred to room temperature and stirred for 15 hours. HPLC analysis showed that starting material 17 remained at <2%, at which point the reaction was stopped. The mixture was filtered through a 30 g diatomaceous earth filter, and the filter cake was washed three times with 20 mL of acetonitrile each time. The filtrate was collected, and the reaction mixture was extracted with ethyl acetate (2 × 500 mL). The organic phase was washed once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 91.40 g of crude product of carboxylic acid compound 18, which is yellow and solid, with a yield of 89.03% and an HPLC purity of 94.36%. It was directly used in the next step without further purification.

[0180] Step 2: Synthesis of Compound 19

[0181] The carboxylic acid-substituted nucleoside product 18 obtained in step one was added to 360 mL of dry DMF. While stirring, HATU (75.24 g, 197.88 mmol, 1.5 eq), N,N-diisopropylethylamine (68.94 mL, 395.76 mmol, 3.0 eq), and ammonium chloride (70.56 g, 1.32 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that the remaining reactant 18 was <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 88.67 g of crude yellow oily amide compound 19, with a yield of 97.15% and a purity of 94.87%. This crude product was directly added to the next step without further purification.

[0182] Step 3: Synthesis of Compound 20

[0183] Under nitrogen protection, IBX (89.72 g, 320.41 mmol, 2.5 eq) was added to 540 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetrabutylammonium bromide (82.44 g, 320.41 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 19 (88.67 g, 128.16 mmol) obtained in step two was added, and the mixture was heated to 80 °C for 2 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. The reaction mixture was extracted with 500 mL of ethyl acetate and 300 mL of water, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 6 hours, filter and dry the filter cake to obtain 73.44 g of white solid 6'-cyano-locked nucleoside compound 20, with a yield of 86.85% and a purity of 97.24%.

[0184] Example 6: Preparation of cyano-locked nucleoside compound 24

[0185]

[0186] Step 1: Synthesis of Compound 22

[0187] First, prepare a mixed solvent of acetonitrile and water at a volume ratio of 3:1. Dissolve 100 g (124.69 mmol) of terminal olefin compound 21 in 800 mL of the acetonitrile and water mixture. While stirring, add ruthenium trichloride (2.59 g, 12.47 mmol, 0.1 eq). After the addition is complete, cool to 10 °C. Add sodium periodate (106.68 g, 498.74 mmol, 4.0 eq) in portions to the cooled system. After the addition is complete, maintain the temperature and stir for 10 minutes. After stirring at room temperature for 20 h, HPLC analysis shows that the remaining reactant 21 is <2%, at which point the reaction is stopped. Filter through a 30 g diatomaceous earth liner, washing the filter cake three times with 20 mL of ethyl acetate each time. Collect the filtrate and extract the reaction solution with ethyl acetate (2 × 500 mL). Wash the organic phase once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 94.47 g of crude product of carboxylic acid compound 22, which is yellow and solid, with a yield of 92.40% and an HPLC purity of 89.87%. It was directly used in the next step without further purification.

[0188] Step 2: Synthesis of Compound 23

[0189] The carboxylic acid-substituted nucleoside product 22 obtained in step one was added to 400 mL of dry DMF. HATU (65.71 g, 172.81 mmol, 1.5 eq), triethylamine (48.04 mL, 345.63 mmol, 3.0 eq), and ammonium chloride (61.62 g, 1.15 mol, 10.0 eq) were added under stirring, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that starting material 22 remained at <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 91.02 g of crude yellow oily amide compound 23, with a yield of 96.46% and a purity of 87.18%. This crude product was directly added to the next step without further purification.

[0190] Step 3: Synthesis of Compound 24

[0191] Under nitrogen protection, IBX (77.80 g, 277.84 mmol, 2.5 eq) was added to 600 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (40.31 g, 277.84 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 3 (91.02 g, 111.13 mmol) obtained in step two was added, and the mixture was heated to 75 °C for 4 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. The reaction mixture was extracted with 500 mL of ethyl acetate and 300 mL of water, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 4 hours, filter and dry the filter cake to obtain 79.00 g of white solid 6'-cyano-locked nucleoside compound 24, with a yield of 90.33% and a purity of 98.02%.

[0192] Example 7: Preparation of cyano-locked nucleoside compound 28

[0193]

[0194] Step 1: Synthesis of Compound 26

[0195] First, prepare a mixed solvent of acetonitrile and water at a volume ratio of 3:1. Dissolve 100 g (127.55 mmol) of terminal olefin compound 25 in 800 mL of the acetonitrile and water mixture. While stirring, add ruthenium trichloride (2.91 g, 14.03 mmol, 0.11 eq). After the addition is complete, cool to 10 °C. Add sodium periodate (114.58 g, 535.71 mmol, 4.2 eq) in portions to the cooled system. After the addition is complete, maintain the temperature and stir for 10 minutes. Transfer to room temperature and stir for 15 h. HPLC analysis shows that the remaining olefin compound 25 is <2%, at which point the reaction is stopped. Filter through a 30 g diatomaceous earth liner, washing the filter cake three times with 20 mL of ethyl acetate each time. Collect the filtrate and extract the reaction solution with ethyl acetate (2 × 500 mL). Wash the organic phase once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 93.52 g of crude product of carboxylic acid compound 26, which is yellow and solid, with a yield of 91.42% and an HPLC purity of 89.05%. It was directly used in the next step without further purification.

[0196] Step 2: Synthesis of Compound 27

[0197] The carboxylic acid-substituted nucleoside product 26 obtained in step one was added to 400 mL of dry DMF. While stirring, HATU (66.51 g, 174.92 mmol, 1.5 eq), N,N-diisopropylethylamine (60.94 mL, 349.84 mmol, 3.0 eq), and ammonium chloride (62.37 g, 1.17 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that the remaining reactant 26 was <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 86.24 g of crude yellow oily amide compound 27, with a yield of 92.33% and a purity of 90.27%. This crude product was directly added to the next step without further purification.

[0198] Step 3: Synthesis of Compound 28

[0199] Under nitrogen protection, Desmond-Martin reagent (114.17 g, 269.17 mmol, 2.5 eq) was added to 600 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (39.06 g, 269.17 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 27 (86.24 g, 107.67 mmol) obtained in step two was added, and the mixture was heated to 80 °C for 2 hours. The reaction was stopped when the residual starting material was less than 2% by HPLC. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. The reaction mixture was extracted with 500 mL of ethyl acetate and 300 mL of water, and the organic phase was separated. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-locked nucleoside product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 4 hours, filter and dry the filter cake to obtain 74.57 g of white solid 6'-cyano-locked nucleoside compound 28, with a yield of 90.07% and a purity of 97.74%.

[0200] Example 8: Preparation of cyano-locked nucleoside compound 32

[0201]

[0202] Step 1: Synthesis of Compound 30

[0203] First, prepare a mixed solvent of acetonitrile and water at a volume ratio of 3:1. Dissolve 100 g (126.26 mmol) of terminal olefin compound 29 in 800 mL of the acetonitrile and water mixture. While stirring, add ruthenium trichloride (2.62 g, 12.63 mmol, 0.1 eq). After the addition is complete, cool to 10 °C. Add sodium periodate (110.72 g, 517.66 mmol, 4.1 eq) in portions to the cooled system. After the addition is complete, maintain the temperature and stir for 10 minutes. Transfer to room temperature and stir for 15 h. HPLC analysis shows that the remaining reactant 29 is <2%, at which point the reaction is stopped. Filter through a 30 g diatomaceous earth liner, washing the filter cake three times with 20 mL of ethyl acetate each time. Collect the filtrate and extract the reaction solution with ethyl acetate (2 × 500 mL). Wash the organic phase once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 94.30 g of crude product of carboxylic acid compound 30, which is yellow and solid, with a yield of 92.21% and an HPLC purity of 95.27%. It was directly used in the next step without further purification.

[0204] Step 2: Synthesis of Compound 31

[0205] The carboxylic acid-substituted nucleoside product 30 obtained in step one was added to 400 mL of dry DMF. While stirring, EDCI (33.48 g, 174.63 mmol, 1.5 eq), N,N-diisopropylethylamine (60.84 mL, 349.26 mmol, 3.0 eq), and ammonia (44.68 mL, 1.16 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 4 hours. HPLC analysis showed that the remaining 30 was <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 91.27 g of crude yellow oily amide compound 31, with a yield of 96.90% and a purity of 94.73%. This crude product was directly added to the next step without further purification.

[0206] Step 3: Synthesis of Compound 32

[0207] Under nitrogen protection, IBX (78.98 g, 282.04 mmol, 2.5 eq) was added to 600 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (40.92 g, 282.04 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 31 (91.27 g, 112.82 mmol) obtained in step two was added, and the mixture was heated to 85 °C for 4 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. The reaction mixture was extracted with 500 mL of ethyl acetate and 300 mL of water, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of dichloromethane to the crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 4 hours, filter and dry the filter cake to obtain 70.54 g of white solid 6'-cyano-locked nucleoside compound 32, with a yield of 80.47% and a purity of 97.74%.

[0208] Example 9: Preparation of cyano-locked nucleoside compound 36

[0209]

[0210] Step 1: Synthesis of Compound 34

[0211] First, prepare a mixed solvent of acetonitrile and water at a volume ratio of 3:1. Dissolve 100 g (200.17 mmol) of terminal olefin compound 33 in 800 mL of the acetonitrile and water mixture. While stirring, add ruthenium trichloride (4.15 g, 20.02 mmol, 0.1 eq). After the addition is complete, cool to 10 °C. Add sodium periodate (171.26 g, 800.69 mmol, 4.0 eq) in portions to the cooled system. After the addition is complete, maintain the temperature and stir for 10 minutes. Transfer to room temperature and stir for 15 h. HPLC analysis shows that the remaining 33 is <2%, at which point the reaction is stopped. Filter through a 30 g diatomaceous earth liner, washing the filter cake three times with 20 mL of ethyl acetate each time. Collect the filtrate and extract the reaction solution with ethyl acetate (2 × 500 mL). Wash the organic phase once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 95.61 g of crude product of carboxylic acid compound 34, which is a yellow solid, with a yield of 92.85% and an HPLC purity of 93.29%. It was directly used in the next step without further purification.

[0212] Step 2: Synthesis of Compound 35

[0213] The carboxylic acid-substituted nucleoside product 34 obtained in step one was added to 400 mL of dry DMF. While stirring, HATU (87.72 g, 230.70 mmol, 1.5 eq), N,N-diisopropylethylamine (80.37 mL, 461.40 mmol, 3.0 eq), and ammonium chloride (82.27 g, 1.54 mol, 10.0 eq) were added, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that the remaining reactant 34 was <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 90.29 g of crude yellow oily amide compound 35, with a yield of 94.59% and a purity of 96.44%. This crude product was directly added to the next step without further purification.

[0214] Step 3: Synthesis of Compound 36

[0215] Under nitrogen protection, IBX (101.84 g, 363.68 mmol, 2.5 eq) was added to 550 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetraethylammonium bromide (52.77 g, 363.68 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 32 (90.29 g, 145.47 mmol) obtained in step two was added, and the mixture was heated to 85 °C for 3 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. The reaction mixture was extracted with 500 mL of ethyl acetate and 300 mL of water, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. Add 100 mL of ethyl acetate to the above crude product, heat to 30 °C and stir until dissolved, add 100 mL of n-hexane, cool to -10 °C and crystallize for 4 hours, filter and dry the filter cake to obtain 84.20 g of white solid 6'-cyano-locked nucleoside compound 36, with a yield of 98.33% and a purity of 97.92%.

[0216] Example 10: Preparation of cyano-locked nucleoside compound 40

[0217]

[0218] Step 1: Synthesis of Compound 38

[0219] First, acetonitrile and water were mixed in a 3:1 volume ratio to prepare a solvent mixture. The R-configured terminal olefin compound 37 (100 g, 120.19 mmol) was dissolved in 800 mL of the acetonitrile and water mixture. Ruthenium trichloride trihydrate (3.14 g, 12.02 mmol, 0.1 eq) was added while stirring. After the addition was complete, the mixture was cooled to 10 °C. Sodium periodate (97.68 g, 456.71 mmol, 3.8 eq) was added in portions to the cooled mixture. After the addition was complete, the mixture was stirred at room temperature for 10 minutes. The mixture was then transferred to room temperature and stirred for 15 hours. HPLC analysis showed that the remaining 37 was <2%, at which point the reaction was stopped. The mixture was filtered through a 30 g diatomaceous earth filter, and the filter cake was washed three times with 20 mL of ethyl acetate each time. The filtrate was collected and the reaction mixture was extracted with ethyl acetate (2 × 500 mL). The organic phase was washed once with sodium chloride. The organic phase was concentrated under reduced pressure to obtain 86.20 g of crude product of carboxylic acid compound 38, which is yellow and solid, with a yield of 84.38% and an HPLC purity of 91.29%. It was directly used in the next step without further purification.

[0220] Step 2: Synthesis of Compound 39

[0221] The carboxylic acid-substituted nucleoside product 38 obtained in step one was added to 350 mL of dry DMF. HATU (59.77 g, 157.19 mmol, 1.55 eq), triethylamine (42.29 mL, 304.23 mmol, 3.0 eq), and ammonium chloride (54.24 g, 1.01 mol, 10.0 eq) were added under stirring, and the reaction was carried out at room temperature for 2 hours. HPLC analysis showed that the remaining reactant 38 was <2%, at which point the reaction was stopped. 200 mL of saturated sodium chloride aqueous solution was added to the reaction system, and the mixture was stirred for 5 minutes. The aqueous phase was then extracted twice with 500 mL of ethyl acetate each time. The organic phase was concentrated under reduced pressure to obtain 79.25 g of crude yellow oily amide compound 39, with a yield of 92.04% and a purity of 98.20%. This crude product was directly added to the next step without further purification.

[0222] Step 3: Synthesis of Compound 40

[0223] Under nitrogen protection, IBX (65.34 g, 233.35 mmol, 2.5 eq) was added to 550 mL of anhydrous acetonitrile and stirred for 5 minutes. Tetrabutylammonium bromide (60.05 g, 233.35 mmol, 2.5 eq) was then added and stirred for 10 minutes. Amide compound 39 (79.25 g, 93.34 mmol) obtained in step two was added, and the mixture was heated to 75 °C for 5 hours. HPLC analysis showed that the reactant residue was <2%, at which point the reaction was stopped. The mixture was cooled to room temperature, filtered through a 30 g diatomaceous earth filter, and the filter cake was washed twice with 100 mL of acetonitrile each time. The filtrate was collected and concentrated under reduced pressure. The reaction mixture was extracted with 500 mL of ethyl acetate and 300 mL of water, separating the organic phase. The organic phase was washed once each with 200 mL of sodium bisulfite solution, saturated sodium carbonate solution, and water. The organic phase was concentrated under reduced pressure to obtain the crude 6'-cyano-mononucleotide product. 200 mL of methyl tert-butyl ether was added to the crude product, heated to 30 °C and stirred until dissolved, 600 mL of n-hexane was added, and the mixture was cooled to -10 °C for 4 hours to crystallize. After filtration and drying of the filter cake, 70.49 g of white solid 6'-cyano-locked nucleoside compound 36 was obtained, with a yield of 92.43% and a purity of 98.51%.

Claims

1. A 6'-amide-modified nucleoside of formula III, characterized in that, The structural formula of III is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from, but not limited to: acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [( [Triisopropylsilyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

2. The 6'-amide-modified nucleoside of formula III according to claim 1, characterized in that, Compound III is Formula III-1: R1, R2 and B are defined as in claim 1.

3. The 6'-amide-modified nucleoside of formula III according to claim 1, characterized in that, Compound III is Formula III-2: R1, R2 and B are defined as in claim 1.

4. A compound of formula II, characterized in that, The structure of compound II is as follows: R1, R2 and B are defined as in claim 1.

5. The compound according to claim 4, characterized in that, Compound II is selected from Formula II-1: R1, R2 and B are defined as in claim 1.

6. The compound according to claim 4, characterized in that, Formula II is selected from Formula II-2: R1, R2 and B are defined as in claim 1.

7. A method for preparing a compound of formula IV, characterized in that, The process includes the following steps: Compound III is oxidized with an oxidizing agent, and the oxidation product is then dehydrated to prepare Compound IV. The synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

8. The preparation method according to claim 7, characterized in that, The oxidant is IBX or Dysmart oxidant; the reaction is carried out in an organic solvent, which is one of toluene, methanol, acetonitrile, and DMF, preferably acetonitrile; the oxidation reaction temperature is 40–100°C, preferably 60–90°C; the molar ratio of the compound of formula III, the oxidant, and the phase transfer catalyst is 1:1.0–5.0:1.0–5.0, preferably 1:2.0–3.0:2.0–3.

0.

9. A method for preparing a compound of formula III, characterized in that, The process includes the following steps: Compound II is condensed in the presence of a nitrogen source, a base, and a condensing agent to obtain Compound III. The synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

10. The preparation method according to claim 9, characterized in that, In the ammonium condensation reaction, the base is one of triethylamine, N,N-diisopropylethylamine, pyridine, and potassium carbonate, preferably N,N-diisopropylethylamine; the reaction is carried out in the presence of a condensing agent, which is one or more of HATU and EDCI; the nitrogen source is ammonium chloride or ammonia; the molar ratio of the compound of formula II, the condensing agent, the base, and the nitrogen source is 1:1.0–2.0:1.5–5.0:5.0–15.0, preferably 1:1.2–1.8:2.0–4.0:8.0–12.

0.

11. A method for preparing a compound of formula II, characterized in that, The process includes the following steps: Compound I is oxidized in the presence of an oxidizing agent to generate Compound II, and the synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

12. The preparation method according to claim 11, characterized in that, The oxidant is sodium periodate; the catalyst is one or more of ruthenium trichloride, ruthenium trichloride hydrate, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium dichloride, and cis-bis(2,2-dipyridine)ruthenium dichloride; the oxidation reaction is carried out in a mixed solvent, which is a mixed solvent composed of dimethyl sulfoxide and water, methanol and water, acetonitrile and water, or 1,4-dioxane and water, preferably acetonitrile and water; the reaction temperature is room temperature; the molar ratio of Formula I, oxidant, and catalyst is 1:2 to 8:0.01 to 0.2, preferably 1:3.0 to 5.0:0.05 to 0.

15.

13. A method for preparing a compound of formula IV-1, characterized in that, The process includes the following steps: Compound III-1 is prepared by oxidation and dehydration, and the synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

14. The preparation method according to claim 13, characterized in that, The oxidant is IBX or Dysmart oxidant; the reaction is carried out in an organic solvent, which is one of toluene, methanol, acetonitrile, and DMF, preferably acetonitrile; the oxidation reaction temperature is 40–100°C, preferably 60–90°C; the molar ratio of the compound of formula III-1, the oxidant, and the phase transfer catalyst is 1:1.0–5.0:1.0–5.0, preferably 1:2.0–3.0:2.0–3.

0.

15. A method for preparing a compound of formula IV-2, characterized in that, The process includes the following steps: Compound III-2 is prepared by oxidation and dehydration, and the synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

16. The preparation method according to claim 15, characterized in that, The oxidant is IBX or Dysmart oxidant; the reaction is carried out in an organic solvent, which is one of toluene, methanol, acetonitrile, and DMF, preferably acetonitrile; the oxidation reaction temperature is 40–100°C, preferably 60–90°C; the molar ratio of the compound of formula III-2, the oxidant, and the phase transfer catalyst is 1:1.0–5.0:1.0–5.0, preferably 1:2.0–3.0:2.0–3.

0.

17. A method for preparing a compound of formula III-1, characterized in that, The synthesis involves the following steps: Compound II-1 is condensed in the presence of a nitrogen source, a base, and a condensing agent to obtain compound III-1. The synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

18. The preparation method according to claim 17, characterized in that, In the ammonium condensation reaction, the base is one of triethylamine, N,N-diisopropylethylamine, pyridine, and potassium carbonate, preferably N,N-diisopropylethylamine; the reaction is carried out in the presence of a condensing agent, which is one or more of HATU and EDCI; the nitrogen source is ammonium chloride or ammonia; the molar ratio of the compound of formula II-1, the condensing agent, the base, and the nitrogen source is 1:1.0~2.0:1.5~5.0:5.0~15.0, preferably 1:1.2~1.8:2.0~4.0:8.0~12.

0.

19. A method for preparing a compound of formula III-2, characterized in that, The synthesis involves the following steps: Compound II-2 is condensed in the presence of a nitrogen source, a base, and a condensing agent to obtain compound III-2. The synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

20. The preparation method according to claim 19, characterized in that, In the ammonium condensation reaction, the base is one of triethylamine, N,N-diisopropylethylamine, pyridine, and potassium carbonate, preferably N,N-diisopropylethylamine; the reaction is carried out in the presence of a condensing agent, which is one or more of HATU and EDCI; the nitrogen source is ammonium chloride or ammonia; the molar ratio of the compound of formula II-2, the condensing agent, the base, and the nitrogen source is 1:1.0-2.0:1.5-5.0:5.0-15.0, preferably 1:1.2-1.8:2.0-4.0:8.0-12.

0.

21. A method for preparing a compound of formula II-1, characterized in that, The process includes the following steps: Compound I-1 is oxidized in the presence of an oxidizing agent to generate compound II-1, and the synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

22. The preparation method according to claim 21, characterized in that, The oxidant is sodium periodate; the catalyst is one or more of ruthenium trichloride, ruthenium trichloride hydrate, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium dichloride, and cis-bis(2,2-dipyridine)ruthenium dichloride; the oxidation reaction is carried out in a mixed solvent, which is a mixed solvent composed of dimethyl sulfoxide and water, methanol and water, acetonitrile and water, or 1,4-dioxane and water, preferably acetonitrile and water; the reaction temperature is room temperature; the molar ratio of Formula I-1, oxidant, and catalyst is 1:2 to 8:0.01 to 0.2, preferably 1:3.0 to 5.0:0.05 to 0.

15.

23. A method for preparing a compound of formula II-2, characterized in that, The process includes the following steps: Compound I-2 is oxidized in the presence of an oxidizing agent to generate compound II-2, and the synthetic route is as follows: Wherein, R1 and R2 are independently selected from H or a hydroxyl protecting group; the hydroxyl protecting group is selected from acetyl, tert-butyl, tert-butoxymethyl, methoxymethyl, benzyloxymethyl, tetrahydropyranyl, 1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, p-chlorophenyl, 2,4-dinitrophenyl, benzyl, 2,6-dichlorobenzyl, diphenylmethyl, p-methoxybenzyl, p-nitrobenzyl, di(2-acetoxyethoxy)methyl, 2-trimethylsilylethyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl, triphenylmethylsilyl, [(triisopropyl] [Silyl]oxymethyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, p-valeryl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenylmethyl carbonate, methanesulfonate, p-toluenesulfonate, triphenylmethyl, monomethoxytriphenylmethyl, dimethoxytriphenylmethyl, trimethoxytriphenylmethyl, 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl, 9-phenylxanthine-9-yl, 9-(p-methoxyphenyl)xanthine-9-yl and 2-naphthylmethyl; B is selected from substituted or unsubstituted adenine, guanine, thymine, cytosine, uracil or their respective salts.

24. The preparation method according to claim 23, characterized in that, The oxidant is sodium periodate; the catalyst is one or more of ruthenium trichloride, ruthenium trichloride hydrate, tris(4,7-diphenyl-1,10-phenanthroline)ruthenium dichloride, and cis-bis(2,2-dipyridine)ruthenium dichloride; the oxidation reaction is carried out in a mixed solvent, which is a mixed solvent composed of dimethyl sulfoxide and water, methanol and water, acetonitrile and water, or 1,4-dioxane and water, preferably acetonitrile and water; the reaction temperature is room temperature; the molar ratio of Formula I-2, oxidant, and catalyst is 1:2 to 8:0.01 to 0.2, preferably 1:3.0 to 5.0:0.05 to 0.15.

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