Preparation method of locked nucleic acid intermediate D-ribofuranose derivative

Abstract

The preparation method of the locked nucleic acid intermediate D-ribofuranose derivative, provided by the invention, is simple in steps, stable in process, high in selectivity and easy for industrial production, and has a relatively good application prospect. According to the preparation method, the yield and the purity can be greatly improved, the economic cost is reduced, steps are shortened, multiple operation modes are simplified, the amount of organic waste liquid is remarkably reduced, materials and process conditions with safety risks are eliminated, operation with serious equipment loss is avoided, and the process conditions and the result are stable.

Description

Technical Field

[0001] This invention belongs to the field of nucleic acid intermediate synthesis, specifically relating to a method for preparing a locked nucleic acid intermediate D-furanose derivative. Technical Background

[0002] Locked nucleic acids (LNAs) are oligonucleotide derivatives. Since their discovery at the end of the last century, LNAs have been rapidly applied in fields such as biology, chemistry, and medicine. Specific applications include antisense drug development, SNP genotyping, gene mutation detection, LNA-modified nucleic acid aptamers, and post-tumor treatment monitoring. The 4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranoside intermediate with substituents at positions 3 and 5 is a crucial and irreplaceable intermediate in LNA synthesis, possessing broad market demand and significant application prospects in both scientific research and pharmaceutical production.

[0003] In existing technologies, the high proportion of S-configuration isomers and the difficulty in separation result in high prices for R-configuration target compounds, hindering the development of locked nucleotides. According to existing technologies, commonly used methods for synthesizing R-configuration 4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-furanose are as follows:

[0004] (i) In J.Org.Chem.2010,75,1569-1581, it was disclosed that tert-butyldiphenylchlorosilane was used as the protecting agent and triethylamine was used as the base to abstract the proton from the hydroxyl group of the alcohol. Due to the large steric volume of the TBDPS group, a large steric hindrance effect was formed, and no product with double TBDPS protection was formed. Only a mixture of two sugars with R and S configurations substituted by single TBDPS was obtained, with R:S = 3:1. Finally, the two configuration products were separated in an overall yield of 80%.

[0005]

[0006] (ii) Tetrahedron, 2002, 58, 5335-5345. disclosed the use of n-butyllithium and tert-butyldiphenylchlorosilane as selective hydroxyl protection at -78°C, and the quantitative generation of two single-protected diastereomers in tetrahydrofuran solution for 2 hours, wherein R:S = 1:1.6. After column purification, 38% of the product was obtained from the R configuration and 62% from the S configuration.

[0007]

[0008] (iii) US2007 / 0249049 A1 discloses the use of dichloromethane as solvent, tert-butyldimethylchlorosilane as hydroxyl protecting agent, triethylamine as base, and the addition of a catalytic amount of 4-dimethylaminopyridine. After reacting for 16 hours, a mixture of two diastereomers was obtained, with R:S = 1:1.6. Silica column purification yielded 59% of the R-configuration product and 22% of the S-configuration product.

[0009]

[0010] In summary, the selective generation of R-configured 4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-furanose derivatives all utilizes triethylamine, pyridine, imidazole / DMF, DMAP, butyllithium, and sodium hydride as proton-extracting reagents. Among these, triethylamine is the most widely used organic base for protecting the silyl group on the hydroxyl group. However, the reaction results in low selectivity for isomers, and the separation and purification of the resulting mixture leads to problems such as low product purity and low yield. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the current technology and provide a method for preparing R-configured furanose derivatives that is simple in steps, stable in process, highly selective, and easy to industrialize. It can be applied to the preparation of locked nucleic acid derivatives for further reactions and has good application prospects.

[0012] Specifically, this invention discloses a method for preparing a compound of formula V, the synthetic route of which is as follows:

[0013]

[0014] Where R1 and R2 are hydroxyl protecting groups, respectively; X is a leaving group.

[0015] Furthermore, the synthesis of compound IV includes the following steps:

[0016] Step 1) The diacetone-D-aloose shown in Formula I reacts with the hydroxyl protecting agent R1X under the action of a base to obtain the compound of Formula II;

[0017] Step 2) Formula II undergoes a selective deisopropylidene reaction under acidic conditions to yield compound III;

[0018] Step 3) Compound III is oxidized in an aqueous sodium periodate solution. The oxidation product then undergoes an aldol condensation reaction with formaldehyde to yield compound IV. Formulas I to IV are shown below:

[0019]

[0020] Where R1 is a hydroxyl protecting group and X is a leaving group.

[0021] The beneficial effects of this invention are:

[0022] 1. The synthesis method of this invention can effectively optimize the R / S isomer ratio, from the original 3:1 to 9:1, which greatly increases the yield and purity of the target product.

[0023] 2. The present invention uses a simple recrystallization method to obtain products with higher purity of R configuration. Compared with the existing separation methods, it can improve the yield and is more suitable for industrial production.

[0024] 3. The process conditions of this invention are simple, reducing economic costs, and the intermediates of each step can be separated as separate high-purity products.

[0025] 4. The amount of organic waste liquid is reduced. Compared with the existing technology, the waste liquid generated in the new process of this invention is a very small amount of wastewater, and the post-treatment is more green and environmentally friendly.

[0026] 6. The process conditions of this invention are more user-friendly, eliminating materials with safety hazards in existing processes, such as sodium hydride. It also avoids operations such as concentrated acetic acid, improving process safety and reducing equipment wear and tear. Attached Figure Description

[0027] Figure 1 Example 2: 1H NMR spectrum of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0028] Figure 2 Example 2: High-performance liquid chromatography (HPLC) chromatogram of the recrystallized product (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0029] Figure 3 Example 3: 1H NMR spectrum of (S)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0030] Figure 4 Example 1, Step 1: 1H NMR spectrum of 3-O-(2-naphthylmethyl)-1,2:5,6-bis-O-isopropylidene-α-D-furanose

[0031] Figure 5 Example 1, Step 2: 1H NMR spectrum of 3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-furanose

[0032] Figure 6Example 1, Step 3: 1H NMR spectrum of 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-furanose

[0033] Figure 7 Example 2: High-performance liquid chromatogram of the reaction solution

[0034] Figure 8 Example 3: High-performance liquid chromatogram of the reaction solution

[0035] Figure 9 High-performance liquid chromatogram of the reaction solution in Comparative Example 2

[0036] Figure 10 High-performance liquid chromatogram of the reaction solution of Comparative Example 7 Detailed Implementation

[0037] 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.

[0038] In this invention, halogens refer to fluorine, chlorine, bromine, and iodine;

[0039] In this invention, room temperature refers to 25±5℃;

[0040] Unless otherwise specified, percentage content in this invention refers to mass percentage content.

[0041] In this invention, R / S represents the configuration of the compound, and Y in the examples represents the raw material.

[0042] 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.

[0043] Specifically, the present invention provides a method for preparing a compound of formula V, the synthetic route of which is as follows:

[0044]

[0045] Where R1 and R2 are hydroxyl protecting groups, and X is a leaving group.

[0046] Preferably, R1 and R2 are each independently 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, and triphenylsilyl. [(triisopropylsilyl)oxy]methyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, pivaloyl, 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 or 2-naphthylmethyl, where X is a halogen.

[0047] In the above preparation method, the alkali is selected from one of sodium hydroxide, potassium hydroxide, potassium tert-butoxide, sodium tert-butoxide, potassium carbonate, cesium carbonate, sodium carbonate, sodium bicarbonate, potassium acetate, sodium acetate, sodium hydride, N,N-diisopropylethylamine, triethylamine, imidazole, pyridine, 4-dimethylaminopyridine, 2,6-dimethylpyridine, 1,8-diazabicycloundec-7-ene, triethylenediamine, N-hydroxyphthalimide, N-methylmorpholine, dimethylamine, diethylamine, diisopropylamine, N-methylisopropylamine, diphenylamine, and diisopropylaminolithium; preferably diisopropylamine.

[0048] In the above preparation method, the solvent is selected from organic solvents, specifically N,N-dimethylformamide, dichloromethane, chloroform, dichloroethane, pyridine, dimethyl sulfoxide, ethyl acetate, 2-methyltetrahydrofuran, tetrahydrofuran, acetonitrile, and dioxane; particularly preferred are dichloromethane, N,N-dimethylformamide, and pyridine.

[0049] In the above preparation method, the reaction temperature is -10 to 50°C; the reaction time is 6 to 72 h, preferably 32 to 36 h; and the molar ratio of the compound of formula IV, R2X and the base is 1:1.15 to 1.25:1.35 to 1.65.

[0050] Preferably, in the above preparation method, the reaction is carried out under the protection of an inert gas, wherein the inert gas is nitrogen or argon.

[0051] The above preparation method also includes the following steps: adding compound IV to an organic solvent and heating to 20-40°C while stirring to dissolve; slowly adding alkali in batches, continuing to stir for a certain period of time, then cooling to -10-0°C, adding R2X dropwise, and after the addition is complete, keeping warm for 0.1-2 hours, and then heating to 15-30°C while stirring for 10-72 hours.

[0052] Preferably, after the reaction is complete, the product is post-processed to obtain an organic phase, the organic phase is concentrated, and the concentrated crude product is recrystallized with an organic solvent to obtain the solid product shown in Formula V.

[0053] Further post-treatment involves cooling the reaction solution to -10 to 0°C, slowly adding an acidic solution while maintaining the temperature below 0°C during the addition, and separating the organic phase into layers after the acidic liquid has been added. The organic phase is washed once each with an alkaline aqueous solution, a saturated sodium chloride aqueous solution, and water. The organic phase is then concentrated under reduced pressure and recrystallized with an organic solvent to obtain formula V.

[0054] The acidic solution is an aqueous solution of ammonium chloride, hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid, preferably an aqueous solution of hydrochloric acid; the alkaline solution is an aqueous solution of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, or potassium bicarbonate, preferably an aqueous solution of sodium bicarbonate; the organic solvent for recrystallization is selected from one or more of n-heptane, n-hexane, ethyl acetate, ethanol, toluene, acetonitrile, and acetone, preferably n-heptane.

[0055] Furthermore, the present invention also provides a method for synthesizing a compound of formula IV, the synthesis of which includes the following steps:

[0056] Step 1) The diacetone-D-aloose shown in Formula I reacts with the hydroxyl protecting agent R1X under the action of a base to obtain the compound of Formula II;

[0057] Step 2) Formula II undergoes a selective deisopropylidene reaction under acidic conditions to yield compound III;

[0058] Step 3) Compound III is oxidized in an aqueous sodium periodate solution. The oxidation product then undergoes an aldol condensation reaction with formaldehyde to yield compound IV. Formulas I to IV are shown below:

[0059]

[0060] Where R1 is a hydroxyl protecting group and X is a leaving group.

[0061] R1 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] X is one of the following: [(2-fluorophenyl)-(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 or 2-naphthylmethyl, wherein X is preferably a halogen.

[0062] Step 1) of the synthesis method of the above-mentioned compound IV includes dissolving compound I in an organic solvent, slowly adding a base under stirring conditions at low temperature, and after the addition is complete, keeping the temperature for 1 to 5 hours, and then slowly adding a solution of the hydroxyl protecting reagent dropwise to the above-mentioned cooled system to prepare compound II; the organic solvent is one of 2-methyltetrahydrofuran and ethyl acetate; the molar ratio of compound I, R1X and base is 1:1.05 to 1.15:1.55 to 1.65.

[0063] Furthermore, the crude product of Formula II obtained in step 1) is recrystallized to obtain a high-purity Formula II compound. The recrystallization solvent is selected from one or more of n-heptane, 2-methyltetrahydrofuran, and ethyl acetate; preferably a mixed solvent of n-heptane and 2-methyltetrahydrofuran or a mixed solvent of n-heptane and ethyl acetate, wherein the volume ratio of n-heptane to 2-methyltetrahydrofuran or ethyl acetate is 1.8 to 2.2:1.

[0064] In step 2) of the synthesis method of the above-mentioned compound IV, the acidic condition is an aqueous solution of acetic acid; the volume ratio of acetic acid to water is 1:0.2 to 30, preferably 1:6; the molar ratio of the compound of formula II to acid is 1:3 to 20, preferably 1:10; and the reaction temperature is 20 to 50°C.

[0065] In step 3) of the synthesis method of the above-mentioned compound IV, sodium periodate is first dissolved in water, then the temperature is lowered to 5℃~10℃, and 1,4-dioxane solution of formula III is added dropwise. After the addition is completed, the temperature is raised to room temperature for reaction.

[0066] In step 3) of the synthesis method of compound IV above, after the reaction of III with sodium periodate is completed, ethylene glycol is added to quench the sodium periodate. Then, formaldehyde aqueous solution is added, followed by slow dropwise addition of alkaline aqueous solution. After the addition is complete, the mixture is kept warm and stirred for 0.2 to 1 hour, and then the temperature is raised to 30°C to 40°C for reaction.

[0067] Preferably, in step 3) above, the molar ratio of compound III, sodium periodate, ethylene glycol, formaldehyde, and alkali is 1:1.2–1.3:0.6–0.8:8–12:2.5–3.5. The formaldehyde aqueous solution is preferably a 37% formaldehyde solution; the alkali is sodium hydroxide, potassium hydroxide, lithium hydroxide, potassium tert-butoxide, sodium methoxide, sodium ethoxide, potassium carbonate, sodium carbonate, or cesium carbonate, preferably sodium hydroxide; the concentration of the alkali is 3%–50%, preferably 10%; the volume ratio of the solvent 1,4-dioxane to water is 1:5–10, preferably 1:6.

[0068] 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.

[0069] Example 1: Synthesis of 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0070]

[0071] Step 1: Synthesis of 3-O-(2-naphthylmethyl)-1,2:5,6-bis-O-isopropylidene-α-D-ribofuranosyl

[0072] Add 30.00 L of 2-methyltetrahydrofuran and diacetone-D-allose (6.00 kg, 23.05 mol) to the reactor. Cool to -5 to 0 °C. Slowly add potassium tert-butoxide (3.88 kg, 34.58 mol) to the reactor in multiple batches. After the addition is complete, continue stirring at 0 °C for 2 hours. Dissolve 5.61 kg of 2-bromomethylnaphthalene (25.36 mol) in 6.00 L of 2-methyltetrahydrofuran. Add the 2-bromomethylnaphthalene solution in 2-methyltetrahydrofuran dropwise to the reactor, keeping the temperature below 0 °C during the addition. After the addition is complete, stir at 0 °C for 30 minutes, then raise the temperature to about 30 °C and stir for 3 hours. Stop the reaction. HPLC shows that the remaining diacetone-D-allose is <1%. Cool to 20 °C and add 9.00 L of water dropwise, stirring for 30 minutes. After standing for 1 hour, separate the contents. The organic phase was washed once with 9.00 L of water. After concentration under reduced pressure, the organic phase was crystallized with 12.00 L of n-heptane and 6.00 L of 2-methyltetrahydrofuran. After centrifugation, filtration, and drying, 8.66 kg of a white powdery solid 1,2:5,6-bis-O-isopropylidene-3-O-(2-naphthylmethyl)-α-D-furanibose was obtained, with a melting point of 91–93 °C, a purity of 98.83%, and a yield of 93.81%.

[0073] 1 H NMR(300MHz,Chloroform-d)δ7.88–7.81(m,4H),7.56–7.47(m,3H),5.77–5.74(m,1H),4.98–4.92(m,1H),4.77(d,J=9.0Hz,1H),4 .59(t,J=4.1Hz,1H),4.40–4.35(m,1H),4.19–4.13(m,1H),4.07–3.91(m,3H),2.17(s,1H),1.63(s,3H),1.38(s,5H),1.37(s,3H).

[0074] Step 2: Synthesis of 3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl

[0075] 12.37 L (216.25 mol) of glacial acetic acid was added to the reaction vessel, followed by 8.66 kg (21.62 mol) of 1,2:5,6-bis-O-isopropylidene-3-O-(2-naphthylmethyl)-α-D-ribofuranosyl (R-furanosyl) obtained in step one. The mixture was stirred for 1 hour until completely dissolved. 74.22 L of water was added dropwise to the reaction vessel. After the addition was complete, the temperature was raised to approximately 30 °C and stirred for 24 hours. The reaction was then stopped. HPLC showed that <2% of the starting material remained. The mixture was cooled to 20 °C, filtered, and centrifuged. The filter cake was soaked three times, once each in 17.32 L of 1% sodium bicarbonate aqueous solution and once in water, for 1 hour each time, and then centrifuged. After drying, the filter cake yielded 6.74 kg of a pale yellow powder solid 3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl, with a melting point of 86–88 °C, a purity of 96.21%, and a yield of 86.48%.

[0076] 1 H NMR (300MHz, Chloroform-d) δ7.88–7.82(m,4H),7.52–7.47(m,3H),5.77(d,J=3.6Hz,1H),4.95(d,J=11.4Hz,1H),4.73(d,J=11. 4Hz,1H),4.63(t,J=3.9Hz,1H),4.17–4.13(m,1H),4.04–3.95(m,2H),3.77–3.66(m,2H),2.32(s,2H),1.62(s,3H),1.37(s,3H).

[0077] Step 3: Synthesis of 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0078] Add 67.40 L of purified water and 5.00 kg of sodium periodate to the reactor, and stir for 1 hour until completely dissolved. Cool to 5–10 °C, and add 6.74 kg (18.70 mol) of 3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl (3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl) obtained in step 3 to 10.11 L of 1,4-dioxane, and stir for 1 hour until completely dissolved. Slowly add the 1,4-dioxane solution of 3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl (3-O-(2-naphthylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl) to the above sodium periodate system, keeping the temperature below 20 °C during the addition. After the addition is complete, maintain the temperature and continue stirring for 30 min. Raise the temperature to 25 °C and stir for 4 hours. HPLC shows that <1% of the raw material remains. Add 0.81 kg (13.09 mol) of ethylene glycol and continue stirring for 1 hour. Then, a 37% formaldehyde aqueous solution (15.18 kg, 187.01 mol) was added to the reactor. After the addition was complete, a 10% sodium hydroxide aqueous solution (22.44 kg, 56.10 mol) was slowly added dropwise, and the mixture was stirred for 30 minutes after the addition was completed. The temperature was raised to 35°C and stirred for 24 hours. The reaction was then stopped, and HPLC showed that the remaining raw material was <1%. The mixture was cooled to 20°C, filtered, and centrifuged. The filter cake was soaked twice in 14.4 L of water, filtered, and centrifuged. After drying the filter cake, 5.92 kg of a white powder solid 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl was obtained, with a melting point of 148–150°C, a purity of 96.04%, and a yield of 87.83%.

[0079] 1 H NMR(300MHz,Chloroform-d)δ7.87–7.81(m,4H),7.53–7.47(m,3H),5.76(d,J=3.9Hz,1H),4.96(d,J=11.7Hz,1H),4.74(d,J=11.7Hz,1H),4.68– 4.65(m,1H),4.27(d,J=5.2Hz,1H),3.95(d,J=1.1Hz,2H),3.80(d,J=12. 0Hz, 1H), 3.60 (d, J = 12.0Hz, 1H), 1.92 (s, 2H), 1.66 (s, 3H), 1.34 (m, 3H).

[0080] Example 2: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0081]

[0082] Add 27.50 L of dichloromethane to the reactor, followed by 5.50 kg (15.26 mol) of 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranoside. Heat to 30 °C and stir for 30 min until dissolved. Add 2.47 kg (24.42 mol) of diisopropylamine and continue stirring for 30 min. Cool to -5 °C. Slowly add 5.03 kg (18.31 mol) of tert-butyldiphenylchlorosilane, keeping the temperature below 0 °C during the addition. After the addition is complete, maintain the temperature and stir for 30 min. Then, raise the temperature to 20 °C and stir for 36 hours. Stop the reaction. HPLC showed that the ratio of R configuration, S configuration, and starting material Y was 90:10:0. The solution was cooled to -5°C, and 19.25 L of 1N HCl was slowly added dropwise while maintaining the temperature below 0°C. After the addition was complete, the solution was stirred for 30 minutes, and the pH of the aqueous phase was measured to be 5–6. The solution was allowed to stand for 1 hour and then separated. The organic phase was washed once each with 11.00 L of 9% NaHCO3 aqueous solution, saturated sodium chloride solution, and water. The organic phase was concentrated under reduced pressure and recrystallized from n-heptane. After filtration, centrifugation, and drying, 7.61 kg of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside was obtained as a white powder solid with a melting point of 98–100°C, a purity of 99.47%, and a yield of 83.28%.

[0083] 1 H NMR(300MHz,Chloroform-d)δ7.85–7.78(m,4H),7.62–7.46(m,7H),7.41–7.27(m,6H),5.81(d,J=3.7Hz,1H),4.97(d,J=12.0Hz,1H), 4.74–4.64(m,2H),4.48(d,J=5.2Hz,1H),3.94–3.80(m,2H),3.80–3.65(m,2H),1.99(br,1H),1.67(s,3H),1.38(s,3H),0.92(s,9H).

[0084] Example 3: Synthesis of (S)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0085]

[0086] Under N2 protection, 5.00 L of dry DMF was added to a 25.00 L reactor, followed by 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranoside (1.00 kg, 2.77 mol) and 2,6-dimethylpyridine (0.39 kg, 3.61 mol). The mixture was stirred for 30 minutes until completely dissolved. Tert-butyldiphenylchlorosilane was dissolved in 2.00 L of dry DMF, and the DMF solution was slowly added dropwise to the reactor. After the addition was complete, the mixture was stirred for 1 hour, and the reaction was stopped. HPLC showed that the ratio of R configuration, S configuration, and starting material Y was 12:88:0. 1.00 L of water was added to the reaction mixture, and the mixture was stirred for 1 hour. The solvent was then removed by concentration under reduced pressure. 2.00 L of dichloromethane and 8.00 L of water were added to extract the reaction mixture, and the organic phase was introduced into the reactor. The solution was cooled to -5 to 0°C and washed once each with 2.00 L of 1N hydrochloric acid, 9% sodium bicarbonate aqueous solution, and water. The organic phase was concentrated under reduced pressure and recrystallized from n-heptane. After filtration, centrifugation, and drying, 1.26 kg of a white powder solid (S)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl was obtained, with a purity of 98.16% and a yield of 75.84%.

[0087] 1 H NMR(300MHz,Chloroform-d)δ:7.84–7.75(m,4H),7.74–7.67(m,4H),7.50–7.42( m,3H),7.41–7.31(m,6H),5.70(d,J=3.9Hz,1H),4.86(d,J=12.2Hz,1H),4.75(d,J =12.2Hz,1H),4.56(dd,J=5.2,3.9Hz,1H),4.25–4.15(m,2H),4.15–4.08(m,1H),4 .07–3.98(m,1H),3.64(d,J=12.0Hz,1H),1.87(br,1H),1.25(s,6H),1.05(s,9H).

[0088] Example 4: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-bis(p-methoxytriphenylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl

[0089]

[0090] Add 5.00 L of pyridine to the reactor, then add 1.00 kg (2.77 mol) of 3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranoside and stir for 30 minutes until dissolved. Add 0.45 kg (4.16 mol) of diisopropylamine and stir for 30 minutes. Cool to -5°C. Slowly add 1.08 kg (3.19 mol) of 4,4'-bismethoxytriphenylmethyl chloride, keeping the temperature below 0°C during the addition. Stir for 30 minutes after the addition is complete. Heat to 30°C and stir for 32 hours. Stop the reaction. HPLC shows that the ratio of R configuration, S configuration, and starting material Y is 89:11:0. Cool to 5–10°C and slowly add 2.00 L of water, keeping the temperature below 15°C during the addition. Continue stirring for 30 minutes after the addition is complete, let stand for 1 hour, and then separate the liquids. The organic phase was washed once each with 2.00 L of 9% NaHCO3 aqueous solution, saturated sodium chloride solution, and water. After concentration under reduced pressure, the organic phase was recrystallized from n-heptane, filtered, centrifuged, and dried to obtain 1.47 kg of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-bis(p-methoxytriphenylmethyl)-1,2-O-isopropylidene-α-D-ribofuranosyl, as a white powder with an HPLC purity of 98.36% and a yield of 79.94%.

[0091] 1 H NMR (300MHz, DMSO-d6) δ7.91–7.66(m,5H),7.54–7.31(m,4H),7.29–7.18(m,7H),6.87–6.84(m,4H),5.76–5.58(m,2H),4.80(d,J=12.3H,1 H),4.59–4.56(m,2H),4.30–4.27(m,1H),3.87–3.83(m,1H),3.69(s,7H),3.50–3.46(m,1H),3.29–3.26(m,1H),1.22(s,3H),1.10(s,3H).

[0092] Example 5: Synthesis of 3-O-benzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0093]

[0094] Step 1: Synthesis of 3-O-benzyl-1,2:5,6-bis-O-isopropylidene-α-D-rifuranose

[0095] Add 15.00 L of ethyl acetate and 3.00 kg (11.53 mol) of diacetone-D-allose to the reactor. Cool to 0–5 °C. Slowly add 1.70 kg (17.29 mol) of solid potassium acetate in multiple batches to the reactor, maintaining the temperature below 10 °C. After the addition is complete, maintain the temperature and stir for 30 minutes. Lower the temperature to below 0 °C, and add 1.51 L (12.68 mol) of benzyl bromide dropwise to the reactor, maintaining the temperature below 0 °C during the dropwise addition. After the dropwise addition is complete, maintain the temperature and stir for 30 minutes. Slowly raise the temperature to 50 °C, stir for 2 hours, and stop the reaction. HPLC shows that the remaining diacetone-D-allose is <1%. Cool to 20 °C, add 9.00 L of water dropwise, stir for 30 minutes, let stand for 1 hour, and then separate the liquids. Wash the organic phase once with water. After the organic phase was concentrated under reduced pressure, it was recrystallized with 6.00 L of n-heptane and 12.00 L of ethyl acetate, centrifuged, filtered, and dried to obtain 3.70 kg of white powdery solid 3-O-benzyl-1,2:5,6-bis-O-isopropylidene-α-D-furanose with a purity of 98.02% and a yield of 91.61%.

[0096] Step 2: Synthesis of 3-O-benzyl-1,2-O-isopropylidene-α-D-furanose

[0097] Add glacial acetic acid (6.04 L, 105.59 mol) to the reaction vessel, then add 1,2:5,6-bis-O-(1-methylethylidene)-3-O-benzyl-α-D-ribofuranosyl (3.70 kg, 10.56 mol) generated in step one, and stir for 1 hour until completely dissolved. Add 36.24 L of water dropwise to the reaction vessel. Slowly raise the temperature to about 30 °C, stir for 24 hours, and stop the reaction. HPLC shows that the remaining starting material is <1%. Cool to 20 °C, filter, and centrifuge. Soak the filter cake three times in 7.40 L of 1% sodium bicarbonate aqueous solution and water, respectively, and filter and centrifuge. After drying the filter cake, 2.70 kg of pale yellow powder solid 3-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranosyl is obtained, with a purity of 94.27% and a yield of 82.39%.

[0098] Step 3: Synthesis of 3-O-benzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0099] Add 27.00 L of water to the reactor, then add sodium periodate (2.42 kg, 11.31 mol) and stir to dissolve. Cool to 5–10 °C, and dissolve the 3-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranosyl (2.70 kg, 8.70 mol) obtained in step two in 4.05 L of 1,4-dioxane. Slowly add the 1,4-dioxane solution of 3-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranosyl to the above sodium periodate system, keeping the temperature below 20 °C during the addition. After the addition is complete, maintain the temperature and stir for 30 minutes. Raise the temperature to 25 °C and stir for 4 hours. HPLC shows that the remaining raw material is <1%. Add ethylene glycol (0.32 kg, 5.22 mol) to quench the excess sodium periodate, and continue stirring for 1 hour. A 37% formaldehyde aqueous solution (7.06 kg, 87.00 mol) was added to the reaction vessel, followed by a slow dropwise addition of a 10% sodium hydroxide aqueous solution (10.44 kg, 26.10 mol). The mixture was stirred for 30 min after the addition was complete. The temperature was raised to 35°C and stirred for 24 hours. The reaction was then stopped; HPLC showed that the remaining starting material was <1%. The mixture was cooled to 20°C, filtered, and centrifuged. The filter cake was soaked twice in 5.40 L of water, filtered, and centrifuged again. After drying the filter cake, 2.30 kg of a white powder solid 3-O-benzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl was obtained, with a purity of 97.11% and a yield of 85.19%.

[0100] Example 6: Synthesis of (R)-3,5-O-dibenzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0101]

[0102] Add 5.00 L of dichloromethane to the reactor, then add 1.00 kg (3.22 mol) of 3-O-benzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosylfuranose. Heat to 30 °C and stir for 30 min until dissolved. Cool to -5 °C and add diisopropylamine (0.63 L (4.83 mol) dropwise in portions, stirring for 30 min after each addition. Slowly add benzyl bromide (0.46 L (3.87 mol) dropwise, stirring for 30 min after each addition. Heat to 30 °C and stir for 32 h. Stop the reaction. HPLC shows that the ratio of R configuration, S configuration, and starting material Y is 80:20:0. Cool to 5 °C and slowly add 2.00 L of water dropwise, keeping the temperature below 15 °C during the addition. Continue stirring for 30 min after the addition is complete. Let stand for 1 hour and separate the liquids. The organic phase was washed once each with 2.00 L of 9% NaHCO3 aqueous solution, saturated sodium chloride solution, and water. After concentration under reduced pressure, the organic phase was recrystallized from n-heptane, filtered, centrifuged, and dried to obtain 0.89 kg of (R)-3,5-O-dibenzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl, a white powder with a purity of 98.36% and a yield of 68.97%.

[0103] 1 H NMR(300MHz,Chloroform-d)δ7.36–7.24(m,10H),5.77(d,J=3.9Hz,1H),4.76(d,J=11.8Hz,1H),4.65(dd,J=5.3,3.9Hz,1H),4.57–4.42 (m,3H),4.28(d,J=5.3Hz,1H),3.92(d,J=11.9Hz,1H),3.85(d,J=11.9Hz,1H),3.61–3.50(m,2H),2.37(s,1H),1.64(s,3H),1.35(s,3H).

[0104] Example 7: Synthesis of (R)-3-O-benzyl-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0105]

[0106] Add 5.00 L of dichloromethane to the reactor, followed by 3-O-benzyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl (1.00 kg, 3.22 mol). Heat to 30 °C and stir for 30 min until dissolved. Cool to -5 °C and add diisopropylamine (0.68 L, 4.83 mol) dropwise in portions, maintaining the temperature below 0 °C during the addition. After the addition is complete, maintain the temperature and stir for 30 min. Slowly add tert-butyldiphenylchlorosilane (0.97 kg, 3.54 mol) dropwise, stirring for 30 min after the addition is complete. Heat to 30 °C and stir for 32 h. Stop the reaction. HPLC shows that the ratio of R configuration, S configuration, and starting material Y is 86:14:0. Cool to 5–10 °C. 2.00 L of water was slowly added dropwise, maintaining the temperature below 15 °C during the addition. After the addition was complete, stirring was continued for 30 minutes, and the mixture was allowed to stand for 1 hour before separation. The organic phase was washed once each with 2.00 L of 9% NaHCO3 aqueous solution, saturated sodium chloride solution, and water. The organic phase was concentrated under reduced pressure and recrystallized from n-heptane. After filtration, centrifugation, and drying, 1.26 kg of (R)-3-O-benzyl-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside was obtained as a white powder with an HPLC purity of 97.69% and a yield of 71.26%.

[0107] 1 H NMR(300MHz,Chloroform-d)δ7.73–7.79(m,4H),7.43–7.25(m,11H),5.96(d,J=4.0Hz,1H),4.95(q,J=6.0Hz,1H),4.83(d,J=4.5Hz ,1H),4.64(q,J=6.0Hz,1H),4.57(d,J=5.0Hz,1H),3.95–3.81(m,4H),2.56(t,J=7.0Hz,1H),1.78(s,3H),1.51(s,3H),1.12(s,9H).

[0108] Example 8: Synthesis of (R)-3-O-triphenylmethyl-4-C-hydroxymethyl-5-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0109]

[0110] Step 1: Synthesis of 3-O-triphenylmethyl-1,2:5,6-bis-O-isopropylidene-α-D-ribofuranosyl

[0111] Add 10.00 L of 2-methyltetrahydrofuran and diacetone-D-allose (2.00 kg, 7.68 mol) to the reactor and stir until dissolved. Cool to 0–5 °C. Add potassium carbonate solid (1.38 kg, 9.99 mol) to the reactor in multiple batches, stirring for 30 minutes after each addition. Dissolve triphenylchloromethane (2.36 kg, 8.45 mol) in 2.00 L of 2-methyltetrahydrofuran. Slowly add the triphenylchloromethane-2-methyltetrahydrofuran solution dropwise to the reactor, keeping the temperature below 0 °C during the addition. After the addition is complete, stir for 30 minutes. Raise the temperature to 50 °C and stir for 3 hours. Stop the reaction. HPLC shows that <1% of the diacetone-D-allose remains. Cool to 20 °C and add 4.00 L of water dropwise, stirring for 30 minutes. After standing for 1 hour, separate the liquid and liquid phases. Wash the organic phase once with 4.00 L of water. After the organic phase was concentrated under reduced pressure, it was recrystallized with 12.00 L of n-heptane and 6.00 L of 2-methyltetrahydrofuran, centrifuged, filtered, and dried to obtain 3.45 kg of a white powdery solid 1,2:5,6-bis-O-isopropylidene-3-O-triphenylmethyl-α-D-furanibose, with an HPLC purity of 97.85% and a yield of 89.33%.

[0112] Step 2: Synthesis of 3-O-triphenylmethyl-1,2-O-isopropylidene-α-D-ribofuranosylfuranose

[0113] Add glacial acetic acid (3.93 L, 68.64 mol) to the reaction vessel, then add 1,2:5,6-bis-O-isopropylidene-3-O-triphenylmethyl-α-D-ribofuranosyl (3.45 kg, 6.86 mol) from step one, and stir for 1 hour until completely dissolved. Add 23.52 L of water dropwise to the reaction vessel. Heat to 30 °C and stir for 20 hours, then stop the reaction. HPLC showed that the remaining starting material was <1%. Cool to 20 °C, filter, and centrifuge. Soak the filter cake once in 6.90 L of 1% sodium bicarbonate aqueous solution and twice in water, then filter and centrifuge. After drying the filter cake, 2.85 kg of pale yellow powder solid 3-O-triphenylmethyl-1,2-O-isopropylidene-α-D-ribofuranosyl was obtained, with an HPLC purity of 92.37% and a yield of 89.76%.

[0114] Step 3: Synthesis of 3-O-triphenylmethyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0115] Add 28.50 L of water to the reactor, then add sodium periodate (1.66 kg, 7.77 mol), and stir for 1 hour until completely dissolved. Cool to 5–10 °C. Add the 3-O-triphenylmethyl-1,2-O-isopropylidene-α-D-ribofuranosyl (2.85 kg, 5.98 mol) obtained in step two to 4.28 L of 1,4-dioxane, and stir for 1 hour until completely dissolved. Slowly add the 1,4-dioxane solution of 3-O-triphenylmethyl-1,2-O-isopropylidene-α-D-ribofuranosyl to the above sodium periodate system, keeping the temperature below 20 °C during the addition. After the addition is complete, maintain the temperature and stir for 30 min. Raise the temperature to 25 °C and stir for 4 hours. HPLC shows that the remaining raw material is <1%. Add ethylene glycol (0.22 kg, 3.59 mol), and continue stirring for 1 hour. Then, a 37% formaldehyde aqueous solution (4.86 kg, 59.84 mol) was added to the reactor. After the addition was complete, a 10% sodium hydroxide aqueous solution (7.18 kg, 17.95 mol) was slowly added dropwise, and the mixture was stirred for 30 min after the addition was finished. The temperature was raised to 35℃ and stirred for 24 hours. The reaction was then stopped, and HPLC showed that the remaining raw material was <1%. The temperature was lowered to 20℃, and the mixture was filtered and centrifuged. The filter cake was soaked twice in 5.70 L of water, filtered, and centrifuged. After drying the filter cake, 2.26 kg of a white powder solid 3-O-triphenylmethyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl was obtained, with a purity of 98.37% and a yield of 79.25%.

[0116] Step 4: Synthesis of (R)-3-O-triphenylmethyl-4-C-hydroxymethyl-5-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0117] Add 11.30 L of dichloromethane to the reactor, then add 2.26 kg (4.74 mol) of 3-O-triphenylmethyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl (3-O-triphenylmethyl-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranosyl) obtained in step 3 and stir until dissolved. Add diisopropylamine (0.93 L (6.64 mol) dropwise in multiple batches, stirring for 30 minutes each time. Cool to -5°C and slowly add benzyl bromide (0.68 L (5.69 mol) dropwise, maintaining the temperature below 0°C during the addition. Stir for 30 minutes after the addition is complete. Heat to 30°C and stir for 36 hours. Stop the reaction. HPLC shows that the ratio of R configuration, S configuration, and starting material Y is 82:18:0. Cool to 5–10°C. Slowly add 4.52 kg of water dropwise, maintaining the temperature below 15°C during the addition. Continue stirring for 30 minutes after the addition is complete. Let stand for 1 hour and separate the contents. The organic phase was washed once each with 4.52 L of 9% NaHCO3 aqueous solution, saturated sodium chloride solution, and water. After concentration under reduced pressure, the organic phase was recrystallized from n-heptane, filtered, centrifuged, and dried to obtain 1.93 kg of 3-O-triphenylmethyl-4-C-hydroxymethyl-5-O-benzyl-1,2-O-isopropylidene-α-D-ribofuranosyl as a white powder with an HPLC purity of 97.51% and a yield of 73.64%.

[0118] 1 H NMR(300MHz,Chloroform-d)δ7.58–7.30(m,20H),5.77(d,J=7.0Hz,1H),4.76(d,J=12.3Hz,1H),4.35 –4.16(m,3H),3.79–3.60(m,2H),3.51–3.38(m,2H),3.12(d,J=12.3Hz,1H),1.64(s,3H),1.35(s,3H).

[0119] Comparative Example 1: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0120] The only difference between Comparative Example 1 and Example 2 is that the base used is N,N-diisopropylethylamine.

[0121] HPLC results show: R:S:Y = 60:40:0.

[0122] Comparative Example 2: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0123] The only difference between Comparative Example 2 and Example 2 is that the base used is triethylamine.

[0124] HPLC results show: R:S:Y = 68:32:0.

[0125] Comparative Example 3: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0126] The only difference between Comparative Example 3 and Example 2 is that the base used is pyridine.

[0127] HPLC results showed that R:S:Y = 69:31:0.

[0128] Comparative Example 4: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0129] The only difference between Comparative Example 4 and Example 2 is that the alkali used is DBU.

[0130] HPLC results showed that R:S:Y = 65:31:4.

[0131] Comparative Example 5: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0132] The only difference between Comparative Example 5 and Example 2 is that the base described is N-hydroxyphthalimide.

[0133] HPLC results showed that R:S:Y = 73:25:2.

[0134] Comparative Example 6: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0135] The only difference between Comparative Example 6 and Example 2 is that the alkali used is cesium carbonate.

[0136] HPLC results show: R:S:Y = 55:20:25.

[0137] Comparative Example 7: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0138] The only difference between Comparative Example 7 and Example 2 is that the alkali used is sodium bicarbonate.

[0139] HPLC results show: R:S:Y = 52:24:24.

[0140] Comparative Example 8: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0141] The only difference between Comparative Example 8 and Example 2 is that the base used is 4-dimethylaminopyridine.

[0142] HPLC results show that R:S:Y = 67:32:1.

[0143] Comparative Example 9: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0144] The only difference between Comparative Example 9 and Example 2 is that the alkali used is triethylenediamine.

[0145] HPLC results show: R:S:Y = 63:35:2.

[0146] Comparative Example 10: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0147] The only difference between Comparative Example 10 and Example 2 is that the base described is N-methylmorpholine.

[0148] HPLC results showed that R:S:Y = 77:23:0.

[0149] Comparative Example 11: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0150] The only difference between Comparative Example 11 and Example 2 is that the base used is dimethylamine.

[0151] HPLC results show: R:S:Y = 78:22:0.

[0152] Comparative Example 12: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0153] The only difference between Comparative Example 12 and Example 2 is that the base used is diethylamine.

[0154] HPLC results showed that R:S:Y = 83:17:0.

[0155] Comparative Example 13: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0156] The only difference between Comparative Example 13 and Example 2 is that the base used is diphenylamine.

[0157] HPLC results showed that R:S:Y = 87:13:0.

[0158] Comparative Example 14: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0159] The only difference between Comparative Example 14 and Example 2 is that the base described is N-methylisopropylamine.

[0160] HPLC results showed that R:S:Y = 84:16:0.

[0161] Comparative Example 15: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0162] The only difference between Comparative Example 15 and Example 2 is that the alkali used is lithium diisopropylamino.

[0163] HPLC results showed that R:S:Y = 42:58:0.

[0164] Comparative Example 16: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0165] The only difference between Comparative Example 16 and Example 2 is that the base used is 2,6-dimethylpyridine.

[0166] HPLC results showed that R:S:Y = 25:75:0.

[0167] Comparative Example 17: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0168] The only difference between Comparative Example 17 and Example 2 is that the molar amount of the alkali is 1.2 times the molar amount of the raw material.

[0169] HPLC results showed that R:S:Y = 85:15:0.

[0170] Comparative Example 18: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0171] The only difference between Comparative Example 18 and Example 2 is that the molar amount of the alkali is 1.5 times the molar amount of the raw material.

[0172] HPLC results showed that R:S:Y = 89:11:0.

[0173] Comparative Example 19: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0174] The only difference between Comparative Example 19 and Example 2 is that the molar amount of the alkali is 2.0 times the molar amount of the raw material.

[0175] HPLC results show: R:S:Y = 90:10:0.

[0176] Comparative Example 20: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0177] The only difference between Comparative Example 20 and Example 2 is that the reaction temperature is 10°C.

[0178] HPLC results showed that R:S:Y = 74:15:11.

[0179] Comparative Example 21: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0180] The only difference between Comparative Example 21 and Example 2 is that the reaction temperature is 50°C.

[0181] HPLC results showed that R:S:Y = 83:17:0.

[0182] Comparative Example 22: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0183] The only difference between Comparative Example 22 and Example 2 is that the recrystallization solvent used is n-hexane.

[0184] HPLC results showed that the purity of the obtained product was 97.82%, and the yield was 77.24%.

[0185] Comparative Example 23: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0186] The only difference between Comparative Example 23 and Example 2 is that the recrystallization solvent is ethyl acetate: n-heptane = 1:2.

[0187] HPLC results showed that the purity of the obtained product was 96.13%, and the yield was 82.83%.

[0188] Comparative Example 24: Synthesis of (R)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside

[0189] The only difference between Comparative Example 24 and Example 2 is that the recrystallization solvent is dichloromethane:n-heptane = 1:2.

[0190] HPLC results showed that the purity of the obtained product was 98.01%, and the yield was 83.17%.

[0191] Comparative Example 25: Synthesis of (S)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranoside. The only difference between Comparative Example 25 and Example 3 is that the reaction solvent is dioxane.

[0192] HPLC results showed that R:S:Y = 15:85:0.

[0193] Comparative Example 26: Synthesis of (S)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0194] The only difference between Comparative Example 26 and Example 3 is that the reaction solvent is ethyl acetate.

[0195] HPLC results showed that R:S:Y = 24:76:0.

[0196] Comparative Example 27: Synthesis of (S)-3-O-(2-naphthylmethyl)-4-C-hydroxymethyl-5-O-tert-butyldiphenylsilyl-1,2-O-isopropylidene-α-D-ribofuranosyl

[0197] The only difference between Comparative Example 27 and Example 3 is that the reaction solvent is acetonitrile.

[0198] HPLC results show: R:S:Y = 18:82:0.

[0199] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a compound of formula V, characterized in that, Its synthetic route is as follows: Wherein, R1 and R2 are hydroxyl protecting groups, and X is a leaving group; Preferably, R1 and R2 are each independently 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, and triphenylsilyl. [(triisopropylsilyl)oxy]methyl, chloroacetyl, trichloroacetyl, trifluoroacetyl, diphenylacetyl, pivaloyl, benzoyl, p-phenylbenzoyl, benzoylcarboxylate, 9-fluorenemethyl 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 or 2-naphthylmethyl; X is a halogen.

2. The preparation method according to claim 1, characterized in that, The alkali is selected from one of sodium hydroxide, potassium hydroxide, potassium tert-butoxide, sodium tert-butoxide, potassium carbonate, cesium carbonate, sodium carbonate, sodium bicarbonate, potassium acetate, sodium acetate, sodium hydride, N,N-diisopropylethylamine, triethylamine, imidazole, pyridine, 4-dimethylaminopyridine, 2,6-dimethylpyridine, 1,8-diazabicycloundec-7-ene, triethylenediamine, N-hydroxyphthalimide, N-methylmorpholine, dimethylamine, diethylamine, diisopropylamine, N-methylisopropylamine, diphenylamine, and diisopropylaminolithium; preferably diisopropylamine.

3. The preparation method according to claims 1-2, characterized in that, The reaction temperature is -10 to 50°C; the reaction time is 6 to 72 hours, preferably 32 to 36 hours.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the compound of formula IV, R2X and the base is 1:1.15-1.25:1.35-1.

65.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The synthesis of compound IV includes the following steps: Step 1) The diacetone-D-aloose shown in Formula I reacts with the hydroxyl protecting agent R1X under the action of a base to obtain the compound of Formula II; Step 2) Formula II undergoes a selective deisopropylidene reaction under acidic conditions to yield compound III; Step 3) Compound III is oxidized in an aqueous sodium periodate solution. The oxidation product undergoes an aldol condensation reaction with formaldehyde to obtain compound IV, wherein formulas I to IV are shown below: Wherein, R1 is a hydroxyl protecting group and X is a leaving group; Preferably, R1 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, [( One of the following: 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, or 2-naphthylmethyl; X is a halogen.

6. The preparation method according to claim 5, characterized in that, Step 1) In the organic solvent, compound I is dissolved and the base is slowly added at low temperature under stirring. After the base is added, the mixture is kept warm for 1 to 5 hours. Then, the solution of the hydroxyl protecting agent is slowly added dropwise to the cooled system to prepare compound II.

7. The preparation method according to claims 5-6, characterized in that, The organic solvent mentioned in step 1) is one of 2-methyltetrahydrofuran and ethyl acetate; the molar ratio of the compound of formula I, R2X and the base is 1:1.05-1.15:1.55-1.

65.

8. The preparation method according to claim 5, characterized in that, The acidic condition mentioned in step 2) is an aqueous solution of acetic acid, and the volume ratio of acetic acid to water is 1:0.2 to 30, preferably 1:

6.

9. The preparation method according to claims 1 to 8, characterized in that, In step 2), the molar ratio of compound II to acid is 1:3 to 20, preferably 1:10; the reaction temperature is 20 to 50°C.

10. The preparation method according to claim 5, characterized in that, In step 3), sodium periodate is first dissolved in water, then the temperature is lowered to 5℃~10℃, and a 1,4-dioxane solution of formula III is added dropwise. After the addition is complete, the temperature is raised to 20~30℃ for the reaction. After the reaction is complete, ethylene glycol is added to quench the sodium periodate, followed by an aqueous formaldehyde solution. After the formaldehyde solution is added, an aqueous alkali solution is slowly added dropwise. After the addition is complete, the mixture is kept warm and stirred for 0.2~1h, and then the temperature is raised to 30℃~40℃ for the reaction.

11. The preparation method according to claim 10, characterized in that, The alkali mentioned in step 3) is sodium hydroxide, potassium hydroxide, lithium hydroxide, potassium tert-butoxide, sodium methoxide, sodium ethoxide, potassium carbonate, sodium carbonate, or cesium carbonate, preferably sodium hydroxide; the concentration of the alkali is 3% to 50%, preferably 10%; the solvent is a mixture of 1,4-dioxane and water.

12. The preparation method according to claims 1 to 11, characterized in that, In step 3) above, the molar ratio of compound III, sodium periodate, ethylene glycol, formaldehyde, and alkali is 1:1.2-1.3:0.6-0.8:8-12:2.5-3.5, and the formaldehyde aqueous solution is preferably a 37% formaldehyde solution; the volume ratio of the solvent 1,4-dioxane to water is 1:5-10; preferably 1:6.

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