Preparation method of novel tenofovir prodrug

Abstract

The invention relates to a preparation method of a compound 9-[(R)-2-[[(S)-[[[1-(isopropoxycarbonyl)-1-methyl] ethyl] amino] phenoxyphosphinyl] methoxyl] propyl] adenine fumarate as shown in a formula (I), which comprises the following steps: taking (R)-9-(2-phosphate methoxyl propyl)-adenine as a starting material, and firstly reacting with phenol under a condensing agent to obtain a compound (II); further chlorinating the compound (II) to obtain a compound (III-1), condensing the compound (III-1) with a compound (IV) to obtain a compound (V), salifying the compound (V) with D-(+)-dibenzoyl tartaric acid anhydride, splitting in an acetone / water mixed solvent to obtain a compound (VI), and performing free crystallization on the compound (VI) to obtain a compound (VII), and finally, salifying the compound (VII) and fumaric acid to obtain a compound finished product shown in the formula (I). The synthesis method is high in yield, good in stability, simple to operate and suitable for industrial production of medicines. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of pharmaceutical chemistry, and particularly relates to a preparation method of a novel tenofovir prodrug. Background Art

[0002] Tenofovir Amibufenamide, with the chemical name 9-[(R)-2-[[(S)-[[[1-(isopropoxycarbonyl)-1-methyl]ethyl]amino]phenoxyphosphoryl]methoxy]propyl]adenine fumarate, is a phosphoramidite prodrug of tenofovir and belongs to nucleoside reverse transcriptase inhibitors. Its structure is shown in formula (I). In June 2021, the National Medical Products Administration approved the listing of Tenofovir Amibufenamide tablets, which provides a new treatment option for patients with chronic hepatitis B.

[0003]

[0004] Tenofovir Amibufenamide is a novel second-generation tenofovir and the first domestically developed oral anti-hepatitis B virus drug in China. It is a novel nucleotide reverse transcriptase inhibitor. By optimizing the structure, it has a higher cell membrane penetration rate, is more easily taken up by hepatocytes, realizes liver-targeted therapy, effectively improves the plasma stability of the drug, reduces the systemic exposure of TFV, and is safer for long-term treatment.

[0005] Clinical research results show that: compared with tenofovir disoproxil fumarate, Tenofovir Amibufenamide can achieve similar antiviral efficacy with less than one-tenth of the dose, and its antiviral efficacy is comparable to that of first-line drugs. At the same time, it has less impact on bone density and kidneys, and has better bone and kidney safety.

[0006] CN103665043A reported a preparation method of Tenofovir Amibufenamide, but this method has a too low yield, and uses preparative liquid chromatography to separate the optical isomers (I-a) and (I-b) generated during the reaction process, with cumbersome operation and too high cost, and is not suitable for large-scale preparation.

[0007] CN104558035A reports a method for separating the compound shown in formula (I-a) and its diastereoisomer mixture by salting out crystallization with D-(+)-dibenzoyl tartaric acid and subsequent alkali neutralization, thereby obtaining the compound shown in formula (I-a) with an optical purity of over 95%. CN109384814A discloses recrystallizing the crude product of the compound shown in formula (I-a) in acetonitrile, a mixed solvent of acetonitrile and an aromatic hydrocarbon solvent, or a mixed solvent of acetonitrile and an ether solvent, thereby obtaining the compound shown in formula (I-a) with an optical purity of over 99.8%. However, the above methods have not solved the problems of too low synthesis yield and too high production cost. Therefore, there is an urgent need to find a preparation method of emtricitabine fumarate with a high synthesis yield, simple operation and suitable for industrial production.

[0008] SUMMARY OF THE INVENTION

[0009] In order to solve the problems existing in the prior art, the present invention further studies the preparation method of the compound 9-[(R)-2-[[(S)-[[[1-(isopropoxycarbonyl)-1-methyl]ethyl]amino]phenoxyphosphoryl]methoxy]propyl]adenine fumarate.

[0010] The object of the present invention is to provide a preparation method of the compound shown in formula (I) with a high synthesis yield, avoiding the use of heavy metals, simple operation and suitable for industrial production of drugs, and its process flow is as follows:

[0011]

[0012] It includes the following steps:

[0013] a. Compound (II), phenol, and a condensing agent are added to an aprotic solvent, and the temperature is controlled to 85-95 °C for reaction. After monitoring the reaction to be completed, compound (III) is obtained;

[0014] b. Compound (III) and thionyl chloride are added to a solvent with strong solubility, and the temperature is controlled to 70-80 °C for reaction. After monitoring the reaction to be completed, compound (III-1) is obtained. Compound (III-1) and compound (IV) undergo a condensation reaction to obtain compound (V);

[0015] c. Compound (V) is salted with D-(+)-dibenzoyl tartaric anhydride and then resolved in a mixed solvent of acetone / water to obtain compound (VI);

[0016] d. Compound (VI) is added to an aprotic polar solvent, and an inorganic base is added. After the liberation is completed, crystallization is carried out with an organic solvent to obtain compound (VII);

[0017] e. The compound (VII) is salted with fumaric acid in an organic solvent to obtain the compound of formula (I).

[0018] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the condensation reagent described in step a is selected from 1,3-dicyclohexylcarbodiimide (DCC) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl), and EDC·HCl is preferred.

[0019] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the molar ratio of compound (II), the condensing agent, and phenol in step a is 1:1.5:1.5 to 1:3.0:2.5; preferably, the molar ratio of compound (II), the condensation reagent, and phenol is 1:2:2.

[0020] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the reaction temperature in step a is controlled at 85-95°C.

[0021] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the reaction time in step a is controlled for 15-20 hours, preferably 15-16 hours.

[0022] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the reaction solvent in step a is 1-methyl-2-pyrrolidone (NMP).

[0023] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the specific operation process of step a is as follows: compound (II) and phenol are added to an aprotic solvent, the condensing agent EDC·HCl is added, the temperature is controlled to 85-95°C for reaction, and after monitoring the reaction is completed, compound (III) is obtained.

[0024] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the acyl chloride reagent in step b is thionyl chloride.

[0025] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the solvents used in step b are sulfolane and toluene, and toluene is preferred.

[0026] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the reaction time for the reaction of compound (III) with thionyl chloride in step b is controlled at 40-70 hours, preferably 39-40 hours.

[0027] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), in step b, the reaction temperature between the compound (III) and thionyl chloride is controlled at 70-90 °C, preferably 70-80 °C.

[0028] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), in step b, the molar ratio of the compound (III-1) to (IV) is 1:3.5.

[0029] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), in step b, the reaction temperature between the compound (III-1) and (IV) is controlled at -5 to 25 °C, preferably -5 to 5 °C.

[0030] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), when the compound (III-1) reacts with (IV), the specific preparation method is to first add the compound (IV) / N,N-diisopropylethylamine (DIEA) mixed solution, and then dropwise add dichloromethane.

[0031] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the specific operation process of step b is as follows: the compound (III) and thionyl chloride are added to a solvent with strong solubility, and the temperature is controlled to react at 70-80 °C. After monitoring the reaction to be completed, the compound (III-1) is obtained. The compound (III-1) and the compound (IV) undergo a condensation reaction to obtain the compound (V);

[0032] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the solvent in step c is an acetone / water mixed solvent.

[0033] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the ratio of acetone to water in the solvent used in step c is 1:0.5 to 1:1.5, preferably the ratio of acetone to water is 1:1.

[0034] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the specific operation process of step c is as follows: the compound (V) forms a salt with D-(+)-dibenzoyl tartaric anhydride and then undergoes resolution in an acetone / water mixed solvent to obtain the compound (VI);

[0035] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the solvent in step d is an acetonitrile / isopropyl ether mixed solvent.

[0036] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), in step d, the ratio of compound (VI) / acetonitrile / isopropyl ether is 1 g: 1.5 L: 3 L to 1 g: 2 L: 10 L, and preferably the ratio of compound (VI) / acetonitrile / isopropyl ether is 1 g: 1.5 L: 5 L.

[0037] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the reaction solvent used in step d is an aprotic polar solvent, preferably dichloromethane, acetonitrile, and more preferably dichloromethane.

[0038] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the specific preparation process of step d is: adding compound (VI) to an aprotic polar solvent, adding an inorganic base, and after the liberation is completed, crystallizing with an organic solvent to obtain compound (VII).

[0039] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the specific operation process of step e is: compound (VII) forms a salt with fumaric acid in an organic solvent to obtain the compound of formula (I).

[0040] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the organic solvent used in step e is a mixed solvent of n-heptane / anhydrous methanol.

[0041] In a preferred embodiment of the present invention, in the preparation method of the compound of formula (I), the ratio of n-heptane / anhydrous methanol in the mixed solvent used in step e is 1:1 to 1:5, and preferably 1:4.

[0042] In the present invention, by using EDC·HCl in step a, the yield of the condensation process is improved and the operation process is simplified; in step b, an unconventional feeding method is adopted, first adding a mixed solution of compound (IV) / DIEA, and then dropping dichloromethane, which improves the yield of the target isomer; in step e, an ideal methanol / n-heptane mixed solvent is screened to obtain a target product with higher purity and higher homogeneity.

[0043] Therefore, the preparation method of the present invention has a higher yield, and its total yield is at least 4 times higher than that of the prior art, and the product has high purity, simple operation, and is suitable for industrial production of drugs. Specific Embodiments

[0044] In order to clearly illustrate the technical solutions and technical effects of the present invention, the present invention will be further described in detail below in conjunction with embodiments.

[0045] Example 1

[0046] Add 1-methyl-2-pyrrolidone (NMP) (150 mL), triethylamine (30 mL), phenol (35 g), and compound II (50 g) into a reaction flask. Control the temperature at 45 - 55 °C and stir for 15 - 20 minutes. Then add the condensation reagent. After adding, control the temperature at 85 - 95 °C and stir for 15 - 16 hours. After the reaction is completed, add sodium hydroxide solution to adjust the pH to 10 - 11, extract and wash with ethyl acetate, and collect the aqueous layer. Add purified water and anhydrous methanol to the aqueous layer, add hydrochloric acid to adjust the pH to 3 - 4, and stir to crystallize. Filter and dry to obtain white solid compound III. The reaction conditions with different condensation reagents are shown in Table 1.

[0047] Table 1 Reaction conditions for preparing compound III using different condensation reagents

[0048]

[0049] Conclusion: The research results show that using EDC·HCl as the condensation reagent has simple post-treatment and higher yield.

[0050] Example 2

[0051] Add toluene (2000 mL), compound III (100 g), and thionyl chloride (64 mL) into a reaction kettle. Control the temperature at 70 - 80 °C and stir for 39 - 40 hours. Cool down to -5 - 0 °C, control the temperature at -5 - 5 °C, and dropwise add the mixed solution of compound IV (140 g) / N,N-diisopropylethylamine (107 g). After dropping, control the temperature at -5 - 5 °C and stir for 1 - 1.5 hours. Control the temperature at -5 - 5 °C and dropwise add dichloromethane (400 mL). After adding, raise the temperature to 10 - 30 °C and stir for 15 - 16 hours. After the reaction is completed, add purified water and dichloromethane for extraction in sequence. Wash the organic phase with sodium dihydrogen phosphate solution, add hydrochloric acid to adjust the pH to 3 - 4, separate the layers, collect the aqueous layer. After washing the aqueous layer with ethyl acetate, add dichloromethane, add potassium carbonate solution to adjust the pH to 9 - 10, collect the organic layer, and dry with anhydrous sodium sulfate. Concentrate under reduced pressure to obtain yellow oily compound V (65 g). By HPLC detection, the proportion of compound I-a is 62.78% and the proportion of compound I-b is 37.22%.

[0052] Example 3

[0053] Add toluene (2000 mL), compound III (100 g), and thionyl chloride (64 mL) into the reaction kettle. Stir and react at a controlled temperature of 70 - 80 °C for 39 - 40 hours. Cool down to -5 - 0 °C, control the temperature at -5 - 5 °C, and dropwise add the mixed solution of compound IV (140 g) / N,N - diisopropylethylamine (107 g) / dichloromethane (400 mL). After addition, raise the temperature to 10 - 30 °C and stir and react for 15 - 16 hours. After the reaction is completed, add purified water and dichloromethane in sequence for extraction. Wash the organic phase with sodium dihydrogen phosphate solution, adjust the pH to 3 - 4 with hydrochloric acid, separate the layers, collect the aqueous layer. After washing the aqueous layer with ethyl acetate, add dichloromethane, adjust the pH to 9 - 10 with potassium carbonate solution, collect the organic layer, and dry it with anhydrous sodium sulfate. Concentrate under reduced pressure to obtain a yellow oily compound V (60 g). By HPLC detection, the proportion of compound I - a is 53.97% and the proportion of compound I - b is 46.03%.

[0054] Example 4

[0055] Add acetone (200 mL) and compound V (50 g) into the reaction flask. Control the temperature at 15 - 30 °C and stir for 15 - 20 minutes. Add D-(+)-dibenzoyl tartaric acid anhydrous (16.4 g) and purified water (200 mL), and stir and react at a controlled temperature of 15 - 30 °C for 18 - 19 hours. Filter by suction, collect the filter cake, and dry to obtain compound VI - 1 (50 g). Add acetone (150 mL), compound VI - 1 (50 g), and purified water (150 mL) into the reaction flask. Control the temperature at 40 - 50 °C and stir for 30 - 60 minutes; then cool down the feed liquid, control the temperature at 10 - 20 °C and stir for crystallization for 3 - 3.5 hours. Filter by suction, collect the filter cake, and dry to obtain compound VI - 1 (45 g). Repeat the above pulping operation 4 times, then weigh to obtain compound VI (27 g), with a purity of 98% and an isomer content of 2%.

[0056] Example 5

[0057] Add dichloromethane (450 mL), compound VI (30 g), and purified water (450 mL) into the reaction flask. Add sodium hydroxide solution to adjust the pH to 9 - 10, separate the layers, collect the organic layer. Wash the organic layer with sodium chloride solution and dry it with anhydrous sodium sulfate. Filter, and concentrate under reduced pressure until the remaining material in the kettle is 50 - 100 L. Transfer the feed liquid to a 50 L rotary evaporator, control the water bath temperature at 40 - 50 °C, and concentrate under reduced pressure and weigh to obtain 20 g. Add acetonitrile (30 mL) into the above reaction flask, control the temperature at 40 - 50 °C, dissolve for 20 - 30 minutes, cool down to -5 - 5 °C, and dropwise add isopropyl ether (100 mL). After addition, control the temperature at -5 - 5 °C and stir for crystallization for 3 - 3.5 hours. Filter, dry, to obtain a white solid compound VII (16 g), with a three - step molar yield of 19%. By HPLC detection, the purity is 99.92% and the isomer content is 0.33%.

[0058] Example 6

[0059] Add compound VII (100 g), fumaric acid (24 g) and different solvents into a reaction flask, control the water bath temperature at 65 - 75 °C and stir for 1 - 2 hours, then cool down to 0 - 10 °C and stir for crystallization for 3 - 4 hours. Filter and dry to obtain white solid compound I.

[0060] Table 2 Influence of different solvents on the crystallization effect of compound I

[0061]

[0062] Conclusion: Compound I obtained by recrystallization with methanol / n - heptane has high yield, high purity, good homogeneity, less solvent consumption, and is more suitable for industrial production.

Claims

1. A method for preparing the compound of formula (I) 9-[(R)-2-[[(S)-[[[1-(isopropoxycarbonyl)-1-methyl]ethyl]amino]phenoxyphosphoryl]methoxy]propyl]adenine fumarate, which is characterized in that, It includes the following steps: a. The compound of formula (II) reacts with phenol under the condition of a condensing reagent to obtain the compound of formula (III). ， b. The compound of formula (III) reacts with an acyl chloride reagent to obtain the compound of formula (III-1), and the compound of formula (III-1) and the compound of formula (IV) undergo a condensation reaction to obtain the compound of formula (V). ， c. The compound of formula (V) forms a salt with D-(+)-dibenzoyl tartaric acid anhydride and then is resolved to obtain the compound of formula (VI). ， d. The compound of formula (VI) is freed under basic conditions and then crystallized to obtain the compound of formula (VII). ， e. The compound of formula (VII) forms a salt with fumaric acid in an organic solvent to obtain the compound of formula (I). ； Wherein: The condensing reagent described in step a is EDC·HCl. When the compound (III-1) reacts with (IV) in step b, the specific preparation method is to first add the mixed solution of compound (IV) / N,N-diisopropylethylamine, and then dropwise add dichloromethane. The organic solvent described in step e is a mixed solvent of n-heptane / anhydrous methanol.

2. The preparation method according to claim 1, characterized in that, In step a, the reaction solvent is 1-methyl-2-pyrrolidone, the reaction temperature is 85-95 °C, the reaction time is 15-16 hours, and the molar ratio of compound (II), the condensing reagent, and phenol is 1:1.5:1.5 - 1:3.0:2.

5.

3. The preparation method according to claim 1, characterized in that, In step a, the molar ratio of compound (II), the condensing reagent, and phenol is 1:2:

2.

4. The preparation method according to claim 1, characterized in that, The acyl chloride reagent described in step b is thionyl chloride, the solvent used is toluene, the reaction time of compound (III) and thionyl chloride is 39-40 hours, and the reaction temperature of compound (III) and thionyl chloride is 70-80 °C.

5. The preparation method according to claim 1, characterized in that, In step b, the reaction temperature of compound (III-1) and (IV) is -5 to 5 °C, and the molar ratio of compound (III-1) and (IV) is 1:3.

5.

6. The preparation method according to claim 1, characterized in that, The solvent used in step c is a mixed solvent of acetone / water, where the ratio of acetone / water is 1:

1.

7. The preparation method according to claim 1, wherein The solvent used for crystallization in step d is a mixed solvent of acetonitrile / isopropyl ether, and the ratio of compound (VI) / acetonitrile / isopropyl ether used is 1 g:1.5 L:5 L.

8. The preparation method according to claim 1, wherein The reaction solvent used for freeing under basic conditions in step d is dichloromethane.

9. The preparation method according to claim 1, characterized in that, In step e, the ratio of n-heptane / anhydrous methanol in the mixed solvent is 1:

4.

10. The preparation method according to claim 1, wherein, It includes the following steps: a. Compound (II), phenol, and a condensing agent are added to an aprotic solvent, the temperature is controlled to 85-95 °C for reaction, and after monitoring the reaction to completion, compound (III) is obtained. b. Compound (III) and thionyl chloride are added to a solvent with strong solubility, the temperature is controlled to 70-80 °C for reaction, and after the reaction is completed, compound (III-1) is obtained. Compound (III-1) and compound (IV) undergo a condensation reaction to obtain compound (V). c. Compound (V) forms a salt with D-(+)-dibenzoyl tartaric acid anhydride and then is resolved in a mixed solvent of acetone / water to obtain compound (VI). d. Add compound (VI) to an aprotic polar solvent, add an inorganic base, and after the liberation is completed, crystallize with an organic solvent to obtain compound (VII); e. Compound (VII) forms a salt with fumaric acid in an organic solvent to obtain the compound of formula (I).

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