CN113754665B - Preparation method of nucleoside compound - Google Patents

Abstract

The invention belongs to the technical field of organic synthesis, and discloses a method for synthesizing nucleoside compounds, which are compounds shown in formula I and pharmaceutically acceptable salts thereofA method is provided.

Wherein R is ¹ is-C (═ O) CHR ² R ³ ；R ² Is selected from C ₁ ‑C ₁₀ Alkyl, aralkyl; r ³ Selected from H, amino, C ₁ ‑C ₁₀ An alkyl group; or R ² R ³ Form C ₃ ‑C ₁₀ A carbocyclic group; the synthesis steps are as follows: 1) protecting hydroxyl in a nucleoside drug sugar structure part; 2) condensing with organic acid and 5' -hydroxyl to obtain ester; 3) the ketal protection is removed under acidic conditions. The method has the advantages of short reaction route, small environmental pollution and simple process operation, and is suitable for industrial production.

Description

A kind of preparation method of nucleoside compound

technical field

The invention relates to the technical field of organic synthesis, in particular to a preparation method of a nucleoside compound.

Background technique

Remdesivir, a nucleoside analog, is an RNA-dependent RNA polymerase (RdRp) inhibitor, which can inhibit the synthesis of viral nucleic acid and is antiviral. It is the only drug currently on the market for SARS-CoV-2 infection . Although remdesivir has been approved by the FDA for the treatment of new coronavirus infection (SARS-CoV-2), its efficacy remains in doubt. Due to the long molecular synthesis steps of remdesivir, expensive and requiring mandatory intravenous injection , its application and accessibility are limited.

Therefore, the rapid development of an effective anti-coronavirus drug or vaccine is an important task of current drug research and development.

The research team found that GS-441524, the metabolite of Remdesivir, effectively inhibited SARS-CoV-2 infection in a mouse model. Compared with remdesivir, GS-441524 has a simple structure, short synthesis steps and low cost, and is suitable for rapid mass production as an emergency drug for epidemics. Clinical pharmacokinetic studies of Remdesivir show that the half-life of metabolite GS-441524 in humans is about 27h, with good pharmacokinetic properties. The safety and efficacy of GS-441524 against COVID-19 and other coronavirus infections underscores the need for clinical trials in the treatment of COVID-19. In order to overcome the problems of high polarity and poor membrane permeability of GS-441524, the research group developed an esterified derivative of the candidate drug GS-441524 as an oral anti-COVID-19 drug, which has good oral bioavailability. The success of this study has been disclosed. In Chinese patent application CN2020116139433, the title is a nucleoside compound and its prodrug for treating coronavirus infection, therefore, it is of great significance to study the synthesis process of esterified derivatives of GS-441524 to provide pharmacokinetics and other test raw materials.

Liu et al. (Tetrahedron, 71(9), 1409-1412; 2015) prepared 5'-position amino acid ester prodrugs by first selectively conducting 5'-position nucleoside drugs with triaryl methylation reagents The primary alcohol is protected into ether, and then the remaining active functional groups such as hydroxyl and amino groups are protected with allyloxycarbonylation reagent, and then the triarylmethyl protecting group is selectively removed under acidic conditions, and then condensed with carboxylic acid, and finally Palladium acetate removes the allyloxycarbonyl protecting group to achieve regioselective esterification at the 5'-position. However, this route is long, with many upper protection and deprotection steps, and the atom economy is not high. And some reactions, such as the process of deallyloxycarbonylation, require a low temperature condition of -50 ° C, and the equipment requirements are high, which is not conducive to industrial production.

Scheme 1.Regioselective esterification method at the 5'-position of nucleosides reported by Liu et al.

He Zhonggui et al. (Molecular Pharmaceutics, 2009, 6(1), 315-325) used benzyl chloroformate (Cbz-Cl) to selectively protect the 4-amino group of cytarabine, and then directly condensed with amino acids, and finally Pd catalyzed Hydrogenation deprotection yields the 5'-esterified product. However, this route does not protect the hydroxyl group on the ribose, which leads to a complicated reaction, and 2'- and 3'-substituted products also occur, resulting in a low yield of the target product, which is not suitable for industrial production.

Synthesizing the reported synthetic routes for the 5'-hydroxyl esterification of nucleoside compounds, all have certain shortcomings. Therefore, it is necessary to design a route suitable for industrial production.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a reaction route for nucleoside compounds, which has the advantages of short technological route, little environmental pollution and simple technological operation.

For this reason, the technical scheme provided by the invention is as follows:

A kind of synthetic method of nucleoside compound (formula I),

Wherein, R ¹ is -C(=O)CHR ² R ³ ; R ² is selected from C ₁ -C ₁₀ alkyl, aralkyl; R ³ is selected from H, amino, C ₁ -C ₁₀ alkyl; or R ² R ³ forms a C ₃ -C ₁₀ carbocyclyl;

It includes the following steps:

1) Compound (GS-441524) selectively protects the hydroxyl group in the presence of 2,2-dimethoxypropane and a dehydrating agent to obtain the compound shown in formula II;

2) The compound shown in formula II and organic carboxylic acid are selectively condensed with 5'-hydroxyl group to form ester (formula III);

3) The compound represented by formula III is removed from the ketal protection to obtain a nucleoside compound (formula I).

In some embodiments, the dehydrating agent described in step 1 is p-toluenesulfonic acid, methanesulfonic acid or concentrated sulfuric acid. In some embodiments, the dehydrating agent is concentrated sulfuric acid, and the selective protection of hydroxyl groups is performed at about 35 degrees Celsius to reflux conditions, preferably about 40 degrees Celsius to about 50 degrees Celsius, and more preferably 45 degrees Celsius. . In some embodiments, the dehydrating agent described in step 1 is p-toluenesulfonic acid and methanesulfonic acid, and the selective protection of hydroxyl groups is carried out in refluxing toluene.

In some embodiments, the post-treatment in step 1 is first dissolved with a small amount of ethyl acetate, and then the solution is poured into a poor solvent and stirred, and the poor solvent includes petroleum ether, n-hexane, n-heptane, and the like.

In some embodiments, the organic acid in step 2 is that R is HO-C(=O)CHR ² R ³ ; R ² is selected from C ₁ -C ₁₀ alkyl, aralkyl; R ³ is selected from H, amino , C ₁ -C ₁₀ alkyl; or R ² R ³ forms a C ₃ -C ₁₀ carbocyclyl.

In some embodiments, the condensation reaction in step 2 is carried out in the presence of DCC/DMAP or EDCI/HOBt, preferably the reaction is carried out in a DCC/DMAP system.

In some embodiments, the condensation reaction in step 2 controls the temperature at 5-10° C., and DCC is added dropwise to the reaction system.

In some embodiments, the R ² is selected from C ₁ -C ₈ alkyl, arylmethyl; R ³ is selected from H, amino, C ₁ -C ₆ alkyl; or R ² R ³ forms C ₃ -C ₇ carbocyclyl.

In some embodiments, the R ² is selected from C ₁ -C ₈ alkyl, and R ³ is selected from H.

In some embodiments, the C ₁ -C ₈ alkyl group is methyl, ethyl, propyl, isopropyl, butyl, or isobutyl, and the like.

In some embodiments, the synthetic method of claim 1, the acid used for the deprotection in step 3 comprises concentrated hydrochloric acid, 6N hydrochloric acid, 3N hydrochloric acid, formic acid, 98% formic acid, 80% formic acid, acetic acid, 90% acetic acid , TFA, 95% TFA, PPTS, methanesulfonic acid, p-toluenesulfonic acid monohydrate, etc., preferably 6N hydrochloric acid.

In some embodiments, the synthetic method of claim 1, step 3 is reacted at -10 degrees Celsius to room temperature.

In some embodiments, the nucleoside compound (Formula I) is the following compound:

For the convenience of explanation, taking the synthesis of isobutyrate prodrugs as an example, the structure numbers of intermediates and products are as follows:

In some embodiments, step 1) after the reaction for 3-8 hours, the post-treatment is adjusted to pH 7-8 with sodium bicarbonate, acetone is recovered by distillation under reduced pressure, ethyl acetate is added to the residue, washed with ethyl acetate, dried, and suction filtered Evaporate dry.

In some embodiments, the above-mentioned method for synthesizing a nucleoside compound, step 1) after the reaction for 3-8 hours, the residue after the ethyl acetate is evaporated and slowly added to the poor solvent of the product, and rapidly stirred, The solid was slowly precipitated, filtered with suction, the filter cake was rinsed with a poor solvent, and dried to obtain intermediate II as a white solid.

In some embodiments, in the described synthetic method, step 2) HPLC monitoring reaction raw material consumption is complete, adding acid under ice bath to convert unreacted DCC into DCU, stirring for 10 minutes and then directly suction filtration, and the filtrate is layered , separate the organic layer, the organic layer was washed with acid, alkali, water, saturated sodium chloride, dried over anhydrous sodium sulfate, and the product was directly used for the next step by suction filtration and evaporation; the acid used was 20% citric acid , one of ammonium chloride and 1N hydrochloric acid, and the base used is one or more of saturated sodium bicarbonate solution, saturated sodium carbonate solution and ammonia water. The content of each substance in the reaction process is further detected to determine the specific reaction time, and the results are as follows:

As can be seen from the results in the table, after 3.5 hours of reaction, the raw materials are basically consumed, and a small amount of bisacylated by-product IMP01 begins to be generated. Therefore, the reaction time is preferably 3.5 to 4 hours.

In some embodiments, the deketal protection described in step 3) is carried out in the presence of an acid, and the acid is concentrated hydrochloric acid, 6N hydrochloric acid, 3N hydrochloric acid, formic acid, 98% formic acid, 80% formic acid, acetic acid, 90% formic acid % acetic acid, TFA, 95% TFA, PPTS, methanesulfonic acid, p-toluenesulfonic acid monohydrate, comprehensively considering material price and post-processing factors, preferably 6N hydrochloric acid, the solvent selected for this reaction is selected from 1-6 carbon alcohols Solvents, ether solvents, the alcohol solvents are selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, or different combinations of these solvents; the ether The organic solvent is selected from diethyl ether, methyl tert-butyl ether, diisopropyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethoxyethane, 1,4-dioxane or any of these solvents. Different combinations, preferably tetrahydrofuran. The reaction temperature is -20 to 25°C, preferably 0°C.

In some embodiments, in the synthetic method described in step 3), after the HPLC monitoring reaction is complete, the pH is adjusted to 7-8 with sodium bicarbonate, ethyl acetate is added for extraction, the ethyl acetate layer is washed with water and saturated brine, respectively, and magnesium sulfate Dry, filter and evaporate to dryness to recover the solvent to obtain crude product. The content of each substance in the reaction process is further detected to determine the specific reaction time, and the results are as follows:

It can be seen from the table that the optimal reaction time for 6N HCl deprotection is about 9h.

In some embodiments, the synthetic method, wherein step 3) adopts the method of column chromatography, using dichloromethane and methanol as eluents, can obtain a relatively pure compound represented by formula (I), and its HPLC purity It is 90% or more, preferably 95% or more, and more preferably 97% or more.

The present invention provides a reaction route of nucleoside compounds, which has short technical route, little environmental pollution and simple technological operation.

In order to achieve the purpose of the present invention, the present invention first considers using the compound GS-441524 as the starting material, and through the technical solution of the present invention, the final product can be obtained with only three steps of reaction,

(GS-441524)，而选择GS-441524做为起始物料需要解决如下技术问题：本领域技术人员知晓化合物GS-441524具有1,2,3三个羟基活性基团和4氨基活性基团，第一步需要选择合适的反应条件选择性的保护2,3羟基，经过不断尝试，最终发现在2,2-二甲氧基丙烷与浓硫酸结合可以高度的选择保护 2,3羟基；要获得化合物GS-441524的酯化衍生物，需要式II所示化合物与有机羧酸选择性地在5’-位羟基缩合成酯(式III)；而氨基基本不发生缩合反应

(GS-441524), and selecting GS-441524 as starting material needs to solve the following technical problems: those skilled in the art know that compound GS-441524 has 1, 2, 3 three hydroxyl active groups and 4 amino active groups, The first step is to select suitable reaction conditions to selectively protect the 2,3 hydroxyl group. After continuous attempts, it was finally found that the combination of 2,2-dimethoxypropane and concentrated sulfuric acid can highly selectively protect the 2,3 hydroxyl group; to obtain The esterified derivative of compound GS-441524 requires the compound represented by formula II and organic carboxylic acid to selectively condense into ester (formula III) at the 5'-position hydroxyl group; while the amino group basically does not undergo condensation reaction

After continuous attempts, it was finally found that DCC/DMAP can be used as a condensing agent to selectively condense a hydroxyl group at the 5'-position into an ester, and when EDCI/HOBt or anhydride/triethylamine system is used for condensation, it is easy to generate a considerable proportion of bisacyl. by-products.

In a word, compared with the prior art, the technical scheme provided by the present invention has the following advantages:

1) The technical solution provided by the present invention can obtain the final product only through 3-step reaction, the reaction route is short, no complicated protective group is used, and the atom economy is high. During the condensation reaction, the generation of bisacylated by-products is controlled by slowly adding a condensing agent dropwise at a low temperature.

2) The route adopted by the technical solution provided by the present invention does not use seriously polluted reagents or solvents, and belongs to an environment-friendly process.

3) The route adopted by the technical solution provided by the present invention is mainly carried out between 0-50° C., the equipment cost is low, and the energy consumption is low.

Terminology Description:

In the present invention, "room temperature" refers to ambient temperature, which is from about 10°C to about 40°C. In some embodiments, "room temperature" refers to a temperature from about 20°C to about 30°C; in other embodiments, "room temperature" refers to a temperature from about 25°C to about 30°C; in still other embodiments Among them, "room temperature" refers to 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, and the like.

"Alkyl" is a hydrocarbon containing primary, secondary, tertiary, or ring carbon atoms. For example, an alkyl group can have 1 to 10 carbon atoms (ie, a _C1 - _C10 alkyl group), 1 to ₈ carbon atoms (ie, a _C1 -C8 alkyl group), or 1 to 6 carbon atoms (ie, a C1-C8 alkyl group). , C ₁ -C ₆ alkyl). Examples of suitable alkyl groups include, but are not limited to, methyl (Me, _-CH3 ), ethyl (Et, -CH2CH3), ₁ -propyl (i-Pr, i-propyl, _{-CH2 )} CH ₂ CH ₃ ), 2-propyl (i-Pr, i-propyl, -CH(CH ₃ ) ₂ ), 1-butyl (n-Bu, n-butyl, -CH ₂ CH ₂ CH _{2 )} CH ₃ ), 2-methyl-1-propyl (i-Bu, i-butyl, -CH ₂ CH(CH ₃ ) ₂ ), 2-butyl (s-Bu, s-butyl, -CH (CH ₃ )CH ₂ CH ₃ ), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH ₃ ) ₃ ), 1-pentyl (n-pentyl, -CH 2CH2CH2CH2CH3), ₂ -pentyl (-CH( _{CH3 ) CH2CH2CH3 )} , _{3 -} pentyl (-CH( _{CH2CH3 ) 2 )} , ₂ -methyl -2-butyl (-C(CH ₃ ) ₂ CH ₂ CH ₃ ), 3-methyl-2-butyl (-CH(CH ₃ )CH(CH ₃ ) ₂ ), 3-methyl-1-butane (-CH ₂ CH ₂ CH(CH ₃ ) ₂ ), 2-methyl-1-butyl (-CH ₂ CH(CH ₃ )CH ₂ CH ₃ ), 1-hexyl (-CH ₂ CH ₂ CH _{2 CH2CH2CH3} ), ₂ -hexyl (-CH( _CH3 ) _{CH2CH2CH2CH3 )} , _{3 -} hexyl (-CH( _{CH2CH3 ) ( CH2CH2CH3 ) )} , 2-Methyl-2-pentyl (-C(CH ₃ ) ₂ CH ₂ CH ₂ CH ₃ ), 3-methyl-2-pentyl (-CH(CH ₃ )CH(CH ₃ )CH ₂ CH ₃ ), 4-methyl-2-pentyl (-CH(CH ₃ )CH ₂ CH(CH ₃ ) ₂ ), 3-methyl-3-pentyl (-C(CH ₃ )(CH ₂ CH ₃ ) ₂ ), 2-methyl-3-pentyl (-CH(CH ₂ CH ₃ )CH(CH ₃ ) ₂ ), 2,3-dimethyl-2-butyl (-C(CH ₃ ) ₂ CH ( _CH3 ) ₂ ), 3,3-dimethyl-2-butyl (-CH( _CH3 )C( _CH3 ) ₃ , and octyl ( _- ( _CH2 ) _7CH3 ).

"Aryl" means an aromatic hydrocarbon group derived by removing one hydrogen atom from a single carbon atom of the parent aromatic ring system. For example, an aryl group can have 6 to 20 carbon atoms, 6 to 14 carbon atoms, or 6 to 10 carbon atoms Atom. Typical aryl groups include, but are not limited to, groups derived from benzene (eg, phenyl), substituted benzene, naphthalene, anthracene, biphenyl, and the like, and the like.

"Arylalkyl" refers to an acyclic alkyl group in which one of the hydrogen atoms bonded to a carbon atom (usually a terminal or ^sp3 carbon atom) is replaced by an aryl group. Typical arylalkyl groups include, but are not limited to, benzyl, 2-phenylethan-1-yl, naphthylmethyl, 2-naphthylethan-1-yl, naphthobenzyl, 2-naphthophenyl Ethan-1-yl and the like. Arylalkyl groups can include 7 to 20 carbon atoms, eg, the alkyl moiety is 1 to 6 carbon atoms, and the aryl moiety is 6 to 14 carbon atoms.

Detailed ways

The claims of the present invention will be further described in detail below in conjunction with the specific embodiments.

The preparation method of compound represented by embodiment 1 formula (Ia)

1) In a 500mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add GS-441524 (10g, 0.03mol), add acetone (300mL) dried over magnesium sulfate, and then add 2,2-dimethylformaldehyde Oxypropane (17 g, 0.16 mol) was added dropwise to the system at room temperature with concentrated sulfuric acid (2.4 mL, 0.04 mol), the dropwise addition was completed after 5 min, the solid began to dissolve, the temperature was raised to 45 °C and the reaction was continued for 4 h, and the reaction was monitored by HPLC Complete (OD-3 column, mobile phase: n-hexane/isopropanol = 80:20, flow rate: 0.8 mL/min, injection volume 1 μL), stop the reaction, after cooling in ice bath, add NaHCO ₃ solid to the reaction solution (10g), water (30mL), the pH was adjusted to 7-8 with sodium bicarbonate, the solvent was distilled off under reduced pressure, the residue was diluted with ethyl acetate (300mL), the ethyl acetate layer was respectively water (80mL), saturated common salt Washed with water (80 mL) and dried over anhydrous sodium sulfate. Suction filtration, the filtrate was distilled under reduced pressure to about 100 mL of solvent remaining, the residue was slowly poured into ice-cooled petroleum ether, and vigorously stirred to wash out a large amount of white solids, and suction filtration to obtain 10.5 g of white solids with a yield of 91% .

2) In a 500mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, and add the ketal protection product (10g, 0.03mol) of the previous step, isobutyric acid (3.2g/0.036mol), DMAP (1.8 g, 0.015 mol), purified DCM 150 mL, the reaction flask was stirred in a cold well at 5-10 °C, and a solution of DCC (8 g, 0.04 mol) in DCM (50 mL) was added to the dropping funnel. Slowly add the DCC solution dropwise, control the temperature at about 10 °C, and complete the dropwise addition after 1 hour. After continuing the incubation reaction for 5 hours, HPLC detects that the reaction is complete, and basically no bisacylated product is produced. Add to the reaction system at 5-10 °C. 20% citric acid solution (50 mL) was stirred for 10 min, diluted with DCM (100 mL), and the layers were statically separated. The organic layer was separated, washed with 20% citric acid (100 mL), saturated sodium carbonate (80 mL), water (80 mL), saturated brine (80 mL), and dried over anhydrous sodium sulfate. Suction filtration and evaporated to dryness to obtain 13.1 g of white solid with a yield of 109% (containing part of the by-product dicyclohexylurea DCU), the product was dissolved in 100 mL of DCM, cooled in a -20°C refrigerator, filtered to remove insolubles, and the filtrate was evaporated to dryness 10.8 g of oil was obtained in 90% yield. ¹ H NMR (400MHz, CDCl ₃ )δ(ppm): 7.99(s, 1H), 6.99(d, J=4.6Hz, 1H), 6.62(d, J=4.6Hz, 1H), 5.72(br, 2H) ),5.49(d,J＝6.8Hz,1H),4.93-4.90(dd,J＝6.8Hz,4.3Hz,1H),4.61-4.58(q,J＝4.4Hz,1H),4.44-4.26(m , 2H), 2.61-2.50 (m, 1H), 1.77 (s, 3H), 1.42 (s, 3H), 1.17-1.14 (q, J=3.8Hz, 6H). ¹³ C NMR (100MHz, CDCl ₃ ) δ(ppm): 176.7, 155.2, 147.3, 123.5, 117.2, 116.7, 115.6, 112.6, 100.0, 83.8, 83.0, 82.0, 81.4, 63.1, 33.8, 26.4, 25.6, 18.9.

3) In a 250mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add the condensation product (10.8g, 0.027mol) of step 2, dissolve it with THF (90mL), and place the reaction flask in a cold well at 0°C Stir, slowly add 6N HCl (90 mL, 0.54 mol) dropwise, keep the reaction for 7 h after the addition, monitor the consumption of raw materials by HPLC, stop the reaction, adjust the pH to 7-8 with NaHCO ₃ solid, remove THF by vacuum distillation, there is solid precipitation, use Ethyl acetate was extracted (150 mL×2), the ethyl acetate layers were combined, washed with water (100 mL), saturated brine (100 mL), and dried over magnesium sulfate. Suction filtration and evaporated to dryness to obtain 8 g of crude product, which was subjected to column chromatography (1.2 times of silica gel sample, 5 times of silica gel packed into a column, eluent: dichloromethane/methanol=40:1) to obtain 6.5 g of pure product, and GS-4415241 g was recovered, The yield was 66.3%, the purity: 98.82% (chromatographic conditions: column: OD-3, mobile phase: n-hexane: isopropanol=80:20, flow rate: 0.8 mL/min, injection volume: 1 μL). ¹ H NMR (600MHz, DMSO-d ₆ )δ(ppm): 7.93(s, 1H), 7.89(br, 2H), 6.92(d, J=4.3Hz, 1H), 6.81(d, J=4.3 Hz) ,1H),6.32(d,J＝5.9Hz,1H),5.38(d,J＝5.7Hz,1H),4.7(t,J＝5.2Hz,1H), 4.32-4.30(m,1H),4.25 -4.22(m, 1H), 4.19-4.16(m, 1H), 3.98-3.95(q, J=5.6 Hz, 1H), 2.55-2.50(m, 1H), 1.06-1.05(dd, J=6.8Hz , 1.8Hz, 6H). ¹³ C NMR (150MHz, DMSO-d ₆ )δ(ppm): 176.4, 156.1, 148.4, 124.0, 117.4, 117.0, 110.7, 101.3, 81.7, 79.5, 74.5, 70.6, 63.4, 33.6 ,19.2,19.1.

Embodiment 2 The preparation method of compound represented by formula (Ia)

1) In a 1000mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add GS-441524 (30g, 0.10mol), add toluene (600mL), and then add 2,2-dimethoxypropane ( 51g, 0.48mol), add p-toluenesulfonic acid (0.13mol) to the system at room temperature, the dropwise addition is completed after 10min, the temperature is raised to reflux and the reaction is continued for 2h. _NaHCO3 solid (30g), water (15mL) were added to the liquid, the pH was adjusted to 7-8 with sodium bicarbonate, the solvent was distilled off under reduced pressure, ethyl acetate (500mL), water (100mL) were added to the residue, The organic layer was separated by stirring, and the organic layer was washed with water (100 mL) and saturated brine (100 mL), respectively, and dried over anhydrous sodium sulfate. Suction filtration, the filtrate was distilled under reduced pressure to about 100 mL of solvent remaining, the residue was slowly poured into ice-cooled petroleum ether, and vigorously stirred to wash out a large amount of white solids, and suction filtration to obtain 10.5 g of white solids with a yield of 91% .

2) In the 1000mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, and add the ketal protection product (30g, 0.09mol) of the previous step, isobutyric acid (9.6g/0.108mol), DMAP (5.4 g, 0.045 mol), DCM 300 mL, the reaction flask was stirred in a cold well at 5-10 °C, and a solution of DCC (24 g, 0.12 mol) in DCM (150 mL) was added to the dropping funnel. The DCC solution was slowly added dropwise, and the temperature was controlled at about 10 °C. The dropwise addition was completed after 1 h. After the reaction was continued for 5 h, HPLC detected that the reaction was complete. At 5-10 °C, 20% citric acid solution (50 mL) was added to the reaction system. , After stirring for 10 min, DCU was removed by suction filtration, and the filtrate was statically stratified. Separate the organic layer, wash the organic layer with 20% citric acid (100mL×2), saturated sodium carbonate solution (100mL×1), water (100mL×1), saturated brine (100mL×1), anhydrous sulfuric acid Sodium dry. Suction filtration was evaporated to dryness to obtain 36 g of white solid with a yield of 99.7%, which was directly used in the next reaction without purification.

3) In a 1000mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add the condensation product (36g, 0.09mol) of step 2, dissolve it with THF (300mL), and place the reaction flask in a 0°C cold well and stir , 6N HCl (300mL, 1.8mol) was slowly added dropwise, and the reaction was incubated for 7h after the addition was completed. HPLC monitored that the raw materials were consumed completely, stopped the reaction, and adjusted the pH to 7-8 with NaHCO ₃ solid, distilled under reduced pressure to remove THF, and extracted with ethyl acetate ( 300 mL×2), the ethyl acetate layers were combined, washed with water (150 mL), saturated brine (150 mL), and dried over magnesium sulfate. Suction filtration and evaporated to dryness to obtain 30g of crude product, column chromatography (1.2 times of silica gel mixed sample, 5 times of silica gel packed into a column, eluent: dichloromethane/methanol=40:1), 20g of pure product was obtained, and 0.8g of GS-441524 was recovered. , combined with step 2, the yield is 61.5%, and the purity: 100%.

Embodiment 3 The preparation method of compound represented by formula (Ia)

1) In a 1000mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add GS-441524 (50g, 0.17mol), add acetone (800mL) dried over magnesium sulfate, and then add 2,2-dimethylformaldehyde Oxypropane (86g, 0.82mol) was added dropwise to the system at room temperature with concentrated sulfuric acid (12mL, 0.22mol), added dropwise at 45°C, the dropwise addition was completed after 10min, the reaction was continued for 4h, and the reaction was monitored by HPLC and stopped. After the reaction was cooled in an ice bath, NaHCO solid (50 g) and water (50 mL ₎ were added to the reaction solution, the pH was adjusted to 7-8 with sodium bicarbonate, the solvent was distilled off under reduced pressure, and ethyl acetate was added to the residue. (1000 mL), water (150 mL), and stirring to separate the organic layer, the organic layer was washed with water (200 mL) and saturated brine (200 mL), respectively, and dried over anhydrous sodium sulfate. Suction filtration, the filtrate was distilled under reduced pressure to about 200 mL of solvent remaining, the residue was slowly poured into ice-cooled petroleum ether, and vigorously stirred to wash out a large amount of white solid, and suction filtration to obtain 52 g of white solid with a yield of 93%.

2) In the 1000mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, and add the ketal protection product (40g, 0.12mol), isobutyric acid (12.8g, 0.14mol), DMAP (7.2 mol) of the previous step, respectively. g, 0.06 mol), DCM 600 mL, the reaction flask was placed in a 5-10 °C cold well and stirred, and a solution of DCC (32 g, 0.16 mol) in DCM (250 mL) was added to the dropping funnel. The DCC solution was slowly added dropwise, and the temperature was controlled at about 10 °C. The dropwise addition was completed after 1.5 h. After the reaction was continued for 5 h, HPLC detected that the reaction was complete. At 5-10 °C, 20% citric acid solution (100 mL) was added to the reaction system ) stirring, suction filtration to remove DCU, and the filtrate is statically layered. Separate the organic layer, wash the organic layer with 20% citric acid (100mL×2), saturated sodium carbonate solution (200mL×1), water (100mL×1), saturated brine (100mL×1), anhydrous sulfuric acid Sodium dry. Suction filtration was evaporated to dryness to obtain 50 g of white solid, which was directly used in the next reaction without purification.

3) In a 1000mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add the condensation product (36g, 0.09mol) of step 2, dissolve it with THF (300mL), and place the reaction flask in a 0°C cold well and stir , 6N HCl (300mL, 1.8mol) was slowly added dropwise, and the reaction was incubated for 7h after the addition was completed. HPLC monitored that the raw materials were consumed completely, stopped the reaction, and adjusted the pH to 7-8 with NaHCO ₃ solid, distilled under reduced pressure to remove THF, and extracted with ethyl acetate ( 300 mL×2), the ethyl acetate layers were combined, washed with water (150 mL) and saturated brine (150 mL), respectively, and dried over magnesium sulfate. Suction filtration and evaporated to dryness to obtain 40 g of crude product, which was subjected to column chromatography (1.2 times of silica gel sample, 5 times of silica gel packed into a column, eluent: dichloromethane/methanol=40:1) to obtain 26 g of pure product, and GS-4415242.2 g was recovered, Combined with step 2, yield was 60%, purity: 99.2%.

Example 4 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , the preparation method of 4-dihydroxytetrahydrofuran-2-yl) methyl acetate

The isobutyric acid in step 2 of Example 1 was replaced by acetic acid, and the yield of the crude product was 98%. Compound Ib was prepared according to the remaining steps in Example 1 to obtain 5.6 g of a white solid with a purity of 98.7% and a total yield of 56% in three steps. ¹ H NMR (600 MHz, CD ₃ OD) δ (ppm): 7.86 (s, 1H), 6.89 (t, J=5.0 Hz, 2H), 4.87 (s, 1H), 4.43-4.41 (dd, J=12 Hz , 2.8Hz, 1H), 4.37-4.34(m, 1H), 4.30-4.27 (m, 1H), 4.13(t, J=5.7Hz, 1H), 2.03(s, 3H). ¹³ C NMR(150MHz, CD ₃ OD)δ(ppm): 171.0, 155.8, 146.9, 124.2, 116.6, 116.2, 110.7, 101.1, 81.9, 80.2, 74.1, 70.7, 63.1, 19.3.

Example 5 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , The preparation method of methyl ester of 4 dihydroxytetrahydrofuran-2-yl) propionate

The isobutyric acid in step 2 of Example 1 was replaced by propionic acid, and the crude product yield was 106%. Compound Ic was prepared according to the remaining steps in Example 1 to obtain 5.0 g of a white solid with a purity of 98% and a total yield of 48% in three steps. ¹ H NMR (600 MHz, CD ₃ OD) δ (ppm): 7.86 (s, 1H), 6.90-6.88 (q, J=4.5 Hz, 2H), 4.87-4.86 (m, 1H), 4.46-4.43 (dd , J=12Hz, 2.8Hz, 1H), 4.37-4.36(m, 1H), 4.31-4.28(m, 1H), 4.15(t, J=5.8Hz, 1H), 2.38-2.28(m, 2H), 1.08 (t, J=7.5Hz, 3H). ¹³ C NMR (150 MHz, CD ₃ OD) δ (ppm): 174.3, 155.8, 146.9, 124.2, 116.5, 116.2, 110.7, 101.1, 82.0, 80.1, 74.2, 70.7 ,62.9,26.7,7.9.

Example 6 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , The preparation method of methyl ester of 4-dihydroxytetrahydrofuran-2-yl)butyrate

The isobutyric acid in step 2 of Example 1 was replaced by n-butyric acid, and the crude product yield was 106%. The compound Id was prepared according to the remaining steps in Example 1 to obtain 6.0 g of a white solid with a purity of 97% and a total yield of 56% in three steps. ¹ H NMR (600 MHz, CD ₃ OD) δ (ppm): 7.86 (s, 1H), 6.90-6.88 (q, J=4.5 Hz, 2H), 4.87-4.86 (m, 1H), 4.44-4.42 (dd , J=12Hz, 2.8Hz, 1H), 4.37-4.35(m, 1H), 4.31-4.28(m, 1H), 4.14(t, J=5.8Hz, 1H), 2.32-2.23(m, 2H), 1.62-1.56 (m, 2H), 0.91 (t, J=7.4Hz, 3H). ¹³ C NMR (150 MHz, CD ₃ OD) δ (ppm): 174.3, 155.9, 146.9, 124.3, 116.5, 116.2, 110.7, 101.1, 82.0, 80.1, 74.2, 70.7, 62.8, 35.4, 17.9, 12.5.

Example 7 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , The preparation method of methyl 4-dihydroxytetrahydrofuran-2-yl)nonanoate

Substituting nonanoic acid for isobutyric acid in step 2 of Example 1, the crude product yield was 101%. Compound Ie was prepared according to the remaining steps in Example 1 to obtain 5.2 g of a white solid with a purity of 98% and a total yield of 40.3% in three steps. ¹ H NMR (600 MHz, CD ₃ OD) δ (ppm): 7.86 (s, 1H), 6.90-6.88 (q, J=4.5 Hz, 2H), 4.87-4.86 (m, 1H), 4.43-4.41 (dd , J=12Hz, 2.8Hz, 1H), 4.37-4.35(m, 1H), 4.32-4.29(m, 1H), 4.14(t, J=5.8Hz, 1H), 2.38-2.23(m, 2H), 1.56-1.53 (m, 2H), 1.29-1.27 (m, 10H), 0.87 (t, J=7.0 Hz, 3H). ¹³ C NMR (150 MHz, CD ₃ OD) δ (ppm): 173.7, 155.9, 146.9 ,124.3,116.5,116.2,110.7,101.1,82.0,74.2,70.7,62.8,33.5, 31.5,28.8,28.7,24.6,22.3.

Example 8 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , the preparation method of 4-dihydroxytetrahydrofuran-2-2-ethylbutyric acid methyl ester

The isobutyric acid in step 2 of Example 1 was replaced by 2-ethylbutyric acid, and the crude product yield was 102%. According to the remaining steps in Example 1, the compound If was prepared, and 6.0 g of white solid was obtained, with a purity of 98.3% and a total yield of 51.3% in three steps. ¹ H NMR (600MHz, CD ₃ OD) δ (ppm): 7.86 (s, 1H), 6.89 (s, 2H), 4.87-4.86 (m, 1H), 4.39-4.43 (dd, J=12Hz, 2.8Hz ,1H),4.37-4.35(m,1H),4.14(t, J＝5.8Hz,1H),2.38-2.22(m,1H),1.60-1.45(m,4H),0.86-0.82(m,6H ). ¹³ C NMR (150MHz, CD ₃ OD)δ(ppm): 176.1, 155.9, 146.9, 124.3, 116.6, 116.2, 110.7, 101.1, 81.9, 79.9, 74.2, 70.7, 62.8, 48.9, 24.7, 24.6.10.7 , 10.6.

Example 9 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , The preparation method of methyl 4-dihydroxytetrahydrofuran-2-cyclopropanecarboxylate

The isobutyric acid in step 2 of Example 1 was replaced with cyclopropanecarboxylic acid, and the yield of the crude product was 107%. Compound Ig was prepared according to the remaining steps in Example 1 to obtain 6.7 g of a white solid with a purity of 97% and a total yield of 62% in three steps. ¹ H NMR (600 MHz, CD ₃ OD) δ (ppm): 7.86 (s, 1H), 6.89 (t, J=4.5 Hz, 2H), 4.87-4.86 (m, 1H), 4.46-4.44 (dd, J ＝12Hz, 2.8Hz, 1H), 4.36-4.34(m, 1H), 4.29-4.26(m, 1H), 4.15(t, J＝5.8Hz, 1H), 1.64-1.60(m, 1H), 0.92- 0.87 (m, 4H). ¹³ C NMR (150MHz, CD ₃ OD) δ (ppm): 174.9, 155.9, 146.9, 124.2, 116.6, 116.2, 110.7, 101.1, 80.2, 80.1, 74.2, 70.6, 63.0, 12.1, 7.5, 7.4.

Example 10 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , The preparation method of 4-dihydroxytetrahydrofuran-2-L-valine ester

The isobutyric acid in step 2 of Example 1 was replaced by Boc-protected L-valine, and the yield of column chromatography was 86%. In step 3, the feed ratio of 6N hydrochloric acid was changed to 50 times, and the remaining steps were prepared according to the preparation method in Example 1 to obtain compound Ih to obtain 2.6 g of a near-white solid with a purity of 97% and a total yield of 22.2% in three steps. ¹ H NMR (400MHz, DMSO-d ₆ )δ(ppm): 8.04(br, 1H), 7.92(s, 1H), 7.88(br, 1H), 6.98(d, J=4.6Hz, 1H), 6.85 (d, J=4.5Hz, 1H), 6.38 (br, 1H), 4.73 (d, J=4.8Hz, 1H), 4.34-4.25 (m, 3H), 3.97 (t, J=5.2Hz, 1H) ,3.28(d,J＝5.1Hz,1H),1.89-1.82(m,1H), 0.85-0.80(m,6H).

Example 11 ((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazin-7-yl)-5-cyano-3 , The preparation method of 4-dihydroxytetrahydrofuran-2-D-valine ester

Boc-protected D-valine was used to replace isobutyric acid in Example 10, and compound Ii was prepared through three-step reaction to obtain 2.5 g of a near-white solid with a purity of 98% and a three-step total yield of 21.4%. ¹ H NMR (400 MHz, DMSO-d ₆ ) δ (ppm): 7.92 (s, 1H), 7.88 (br, 2H), 6.92 (d, J=4.2 Hz, 1H), 6.83 (d, J=4.2 Hz, 1H), 6.34(d, J＝5.6Hz, 1H), 5.39(s, 1H), 4.71(s, 1H), 4.33-4.17(m, 3H), 3.97(s, 1H), 3.10(d , J=5.0Hz, 1H), 1.80-1.74 (m, 1H), 0.84-0.74 (m, 6H). ¹³ C NMR (100MHz, DMSO-d ₆ )δ (ppm): 175.0, 155.5, 147.8, 123.4 ,116.8,116.5,110.2,100.7, 81.1,78.9,73.9,70.2,63.1,59.3,31.6,19.1,17.0.

Comparative Example 1

In a 100mL there-necked flask, were respectively added isobutyric acid (0.29g, 3.3mmol), EDCI (0.86g, 4.5mmol), HOBt (0.6g, 4.5mmol), triethylamine (1.5g, 15mmol), DCM 20mL, The reaction flask was placed in a cold well at 5-10°C and stirred. After stirring for 20 minutes, a DCM solution (10 mL) of the ketal-protected product (1 g, 3 mmol) in the previous step was added dropwise to the reaction system. After 16 hours of reaction, HPLC showed that there were still raw materials remaining, and a bisacylated product with a content of 40% was produced. After treatment, the reaction solution was diluted with 50 mL of DCM, and the organic solution was washed with 1N hydrochloric acid, saturated sodium carbonate, and saturated brine, respectively. Dry over sodium sulfate. Suction filtration, evaporated to dryness, and column chromatography to obtain 0.6 g of the condensation product of step 2, with a yield of 50%.

Comparative Example 2

In a 100mL there-necked flask, add ketal protection product (0.5g, 1.5mmol), triethylamine (0.76g, 7.5mmol), DMAP (0.01g, 0.08mmol), dissolve with 10mL of dichloromethane, and place the reaction system in Cool in an ice bath, add isobutyric anhydride (0.24g, 1.6mmol) dropwise, slowly rise to room temperature after the dropwise addition, continue the reaction for 7h, HPLC monitors that most of the conversion is complete, and a large number of bisacylated by-products are produced, there is no choice was separated and purified by column chromatography to obtain 0.26 g of the 5'-esterified product with a yield of 43%.

Comparative Example 3

General steps in the screening process for deprotecting acid conditions

In a 100 mL reactor, the ketal protection product (0.2 g, 0.5 mmol) of step 2 was added, dissolved in 4 mL of THF, the corresponding acid (12.5 mmol) was slowly added under ice bath conditions, and the reaction was continued for 7 h after the addition was raised to room temperature. The reaction was monitored by HPLC, the reaction solution was treated, adjusted to pH 7-8 with sodium bicarbonate, diluted with 10 mL of ethyl acetate, the organic layer was separated, washed with saturated brine, evaporated to dryness to obtain the crude product, which was separated and purified by column chromatography.

ND: Not determined; ^a The product was all converted into GS-441524; ^b the product was very complicated and not separated; ^c The reaction was carried out in dichloromethane medium.

Comparative Example 4

In a 250mL reactor, install a stirrer, a thermometer, and a constant pressure dropping funnel, add the ketal protection product (13.49g, 0.034mol) of step 2, dissolve it with 100mL DCM, place the reaction flask in an ice bath, add dropwise Trifluoroacetic acid (68 mL, 0.918 mol). After ten minutes, the dropwise addition was completed, and the reaction was continued at room temperature for 48 hours. After treatment, the solvent and excess trifluoroacetic acid were removed by distillation under reduced pressure. Water was added to the residue. Under ice bath conditions, 5% sodium hydroxide solution was slowly added dropwise to adjust The pH was adjusted to 7-8, extracted three times with ethyl acetate, and the organic layers were combined, washed with water, washed with saturated brine, and dried over sodium sulfate. Suction filtration and evaporated to dryness, and the crude product was subjected to column chromatography to obtain 7 g of white solid with a yield of 58% and a purity of 98.2%.

The above examples are only used to further illustrate the present invention as (((2R,3S,4R,5R)-5-(4-aminopyrrolo[2,1-f][1,2,4]triazine-7- base)-5-cyano-3,4-dihydroxytetrahydrofuran-2-isobutyric acid methyl ester) preparation method), but the present invention is not limited to the embodiment, all according to the technical essence of the present invention to the above embodiment Any simple modifications, equivalent changes and modifications made all fall within the protection scope of the technical solution of the present invention.

Claims (8)

1. a synthetic method of nucleoside compound formula I,

Wherein, R ¹ is -C(=O)CHR ² R ³ ; R ² is selected from C ₁ -C ₁₀ alkyl, aralkyl; R ³ is selected from H, C ₁ -C ₁₀ alkyl; including the following steps: 1) Compound GS-441524 selectively protects the hydroxyl group in the presence of 2,2-dimethoxypropane and a dehydrating agent to obtain the compound shown in formula II;

2) compound shown in formula II and organic acid are selectively condensed with 5'-hydroxyl group to form ester formula III;

3) The compound shown in formula III is removed from the ketal protection to obtain the nucleoside compound formula I; The condensation reaction described in step 2 is carried out in the presence of DCC/DMAP; The dehydrating agent described in step 1 is concentrated sulfuric acid, and the selective protection of the hydroxyl group is carried out at 35 degrees Celsius to reflux conditions; or the dehydrating agent described in step 1 is p-toluenesulfonic acid, methanesulfonic acid, and the selected The protection of hydroxyl groups was carried out in refluxing toluene. 2. The synthetic method as claimed in claim 1, wherein the post-treatment of step 1 is first dissolved in a small amount of ethyl acetate, and then the solution is poured into a poor solvent and stirred, and the poor solvent includes petroleum ether, n-hexane and n-heptane. 3. The synthetic method of claim 1, wherein the organic acid in step 2 is HO-C(=O)CHR ² R ³ ; wherein R ² is selected from C ₁ -C ₁₀ alkyl, aralkyl; R ³ Selected from H, C ₁ -C ₁₀ alkyl. 4. The synthetic method as claimed in claim 1, wherein the condensation reaction control temperature in step 2 is 5 degrees Celsius-10 degrees Celsius, and DCC is added dropwise to the reaction system. 5. The synthetic method of claim 3, wherein R ² is selected from C ₁ -C ₈ alkyl, arylmethyl; R ³ is selected from H, C ₁ -C ₆ alkyl; or R ² R ³ forms C ₃ -C ₇ carbocyclyl. 6. synthetic method as claimed in claim 1, the acid used for deprotection described in step 3 comprises 6N hydrochloric acid, 3N hydrochloric acid, 98% formic acid, 80% formic acid, 90% acetic acid, 95% trifluoroacetic acid, pyridine-p-toluenesulfonic acid acid salt, methanesulfonic acid, p-toluenesulfonic acid monohydrate. 7. The synthetic method of claim 1, wherein step 3 is reacted at -10 degrees Celsius to room temperature. 8. synthetic method as claimed in claim 1, described nucleoside compound formula I is following compound: