Preparation method of cytarabine

Abstract

The invention belongs to the technical field of cytarabine, and particularly relates to a preparation method of cytarabine. Cytidine reacts in the presence of a condensation reagent and alkali to form cyclo-cytidine, cyclo-cytidine reacts with chloroacetic acid acyl chloride to form a compound C, and the compound C reacts in the presence of ammonia water to form cytarabine or a pharmaceutically acceptable salt thereof. According to the method, a high-toxicity dehydrating agent and complex synthesis steps are not used, and a high-purity cytarabine finished product can be directly obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of cytarabine, and particularly relates to a method for preparing cytarabine. Background Art

[0002] Cytarabine, molecular formula is C9H 13 N3O5, chemical structure is as follows:

[0003]

[0004] Cytarabine is very similar to deoxycytidine and can be incorporated into human DNA instead of deoxycytidine. However, it is not a component of DNA synthesis and will interfere with DNA replication, thereby killing affected cells. When used, cytarabine kills cancer cells by this mechanism of action. It is the first chemotherapy drug that acts by changing the nucleoside itself. Cytarabine is currently one of the most effective drugs used in the clinical treatment of acute non-lymphoid myeloid leukemia in my country. After cytarabine enters the human body, it is converted into cytarabine triphosphate and cytarabine diphosphate after kinase phosphorylation. The former can strongly inhibit the synthesis of DNA polymerase, and the latter can inhibit the conversion of diphosphate cytidine to diphosphate deoxycytidine, thereby inhibiting the synthesis and polymerization of cellular DNA. However, the inhibitory effect of cytarabine on RNA and protein synthesis is very slight.

[0005] The synthesis of cytarabine has been reported both at home and abroad. The most common method is: using cytidine as a raw material, obtaining cyclocytidine hydrochloride under the action of a dehydrating agent, and further ring-opening to obtain cytarabine hydrochloride. This type of synthesis method has the advantages of cheap and readily available raw materials, but also has the disadvantages of low yield and high cost. In addition, since the dehydrating agents currently used are mostly highly toxic substances, they are extremely dangerous to the environment and the health of workers.

[0006] The patent publication number CN109422788B points out the synthesis method of cytarabine hydrochloride in the prior art: cytidine is used as a raw material, cyclocytidine hydrochloride is obtained under the action of a dehydrating agent, and cytarabine hydrochloride is further ring-opened. The advantages of this type of synthesis method are that the raw materials are cheap and easy to obtain, but there are also disadvantages of low yield and high cost. In addition, most of the dehydrating agents currently used are highly toxic substances, which bring extremely high risks to the environment and the health of workers.

[0007] Patent Publication No. 113292611B points out that the method of purifying cytarabine by using exchange resin in the prior art includes: 1) using an inert organic solution as a solvent, using ammonia water and then using methanol ammonia for aminolysis, concentrating the reaction system to obtain a concentrated residue (crude cytarabine); 2) purifying the residue (crude cytarabine) by using a cation exchange resin column, eluting with deionized water and dilute ammonia water, collecting the product eluate, and concentrating the eluate in vacuo to obtain crude cytarabine.

[0008] In general, in the prior art, the synthesis process of cytarabine has high raw material cost, complex process, many by-products, low yield and high pollution. In order to reduce cost, reduce pollution and improve yield, the present invention provides a new and safe method for preparing and purifying high-quality cytarabine. Summary of the invention

[0009] The present invention aims at the deficiencies of the prior art and provides a method for preparing cytarabine.

[0010] The technical solution of the present invention is as follows:

[0011] The present invention provides a method for preparing cytarabine, comprising the following steps:

[0012] Cytidine reacts in the presence of a condensation reagent and a base to form cyclocytidine, cyclocytidine reacts with chloroacetic acid chloride to form compound C, and compound C reacts in the presence of ammonia water to form cytarabine.

[0013] In one embodiment of the present invention, the condensation reagent includes trichloro-s-triazine; and the base includes triethylamine or N,N-diisopropylethylamine.

[0014] In one embodiment of the present invention, the molar ratio of cytidine to the condensation reagent is 1:0.9 to 1:2.

[0015] Furthermore, 1:0.9-1:2 includes 1:0.9, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2 or any value between two numbers.

[0016] Preferably, the molar ratio of cytidine to the condensation reagent is 1:0.9 to 1:1.5.

[0017] In one embodiment of the present invention, the molar ratio of cytidine to base is 1:1 to 1:4.

[0018] Furthermore, 1:1-1:4 includes 1:1, 1:2, 1:2.2, 1:2.4, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.8, 1:4 or values ​​between any two numbers.

[0019] Preferably, the molar ratio of cytidine to base is 1:1 to 1:3.

[0020] In one embodiment of the present invention, the molar ratio of cyclocytidine to chloroacetic acid chloride is 1:0.9 to 1:2.

[0021] Furthermore, 1:0.9-1:2 includes 1:0.9, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2 or any value between two numbers.

[0022] Preferably, the molar ratio of cyclocytidine to chloroacetic acid chloride is 1:0.9-1.5.

[0023] Further, cyclocytidine is reacted with chloroacetic acid chloride in an aprotic polar solvent, and the aprotic polar solvent is selected from tetrahydrofuran.

[0024] In one embodiment of the present invention, the specific preparation steps include: cytidine, trichloro-s-triazine and triethylamine react in N,N-dimethylformamide solvent at room temperature to form cyclocytidine.

[0025] In one embodiment of the present invention, the specific preparation steps include: cyclocytidine and chloroacetic acid chloride react under an organic base condition to form compound C, and the organic base includes triethylamine or pyridine.

[0026] In one embodiment of the present invention, the specific preparation steps include: purifying compound C to obtain purified compound C, and reacting the purified compound C under ammonia water condition to form cytarabine;

[0027] The method for purifying compound C comprises: adding compound C to a pulping solution, heating and stirring, pulping after cooling, washing, and drying to obtain purified compound C;

[0028] The slurry solution includes at least one of methanol and ethyl acetate.

[0029] It should be noted that the present invention is equivalent to also providing a method for purifying cytarabine intermediates. In the method of the present invention, compound C is easy to purify, and the chloroacetyl group in the structure is easy to leave. The purified compound C can be converted into cytarabine under corresponding conditions, and the obtained cytarabine has a high purity of not less than 98.0%, 98.2%, 98.4%, 98.6%, 98.8%, 99.0% or higher; at the same time, the method for adding or removing the chloroacetyl group is also relatively simple, such as under ammonia conditions.

[0030] Furthermore, the solvent volume ratio of methanol / ethyl acetate is 1:1 to 1:10.

[0031] Furthermore, 1:1-1:10 includes 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10 or any value between two numbers.

[0032] Further, in some embodiments, in the method, compound C reacts in the presence of aqueous ammonia to form cytarabine. In some embodiments, compound C reacts in the presence of aqueous ammonia at 60-80° C. to form cytarabine or a pharmaceutically acceptable salt thereof.

[0033] Further, the synthetic route of cytarabine is as follows:

[0034]

[0035] The present invention also prepares cytarabine acetate: compound C forms cytarabine acetate under the conditions of ammonia water and acetic acid solution.

[0036] In other embodiments, compound C is salified in an acetic acid-methanol solvent to form arabinoside acetate. The arabinoside acetate is slurried in isopropanol, filtered, and washed to obtain high-purity arabinoside acetate.

[0037] In some embodiments, cytarabine acetate is dissolved in water, and sodium bicarbonate solution is used to adjust the pH to 6-7, and isopropanol solvent is added dropwise, and cytarabine is obtained by filtration. At this time, the purity of cytarabine is not less than 98.4%, 98.6%, 98.8%, 99.0% or higher, and the single impurity is less than 0.1%.

[0038] On the other hand, the preparation method of the present invention further comprises one or more steps of filtration, concentration and drying.

[0039] It should be noted that "formation" and "conversion into" do not specifically mean that the conversion reaction between two substrates is a single step, and can be a single step or multi-step reaction between two substrates. If the intermediate contains a protecting group, the intermediate is subjected to a step of removing the protecting agent, and then reacts with the corresponding substrate to obtain the corresponding target product.

[0040] The numerical values ​​in the present invention are instrumental measurements, which have a certain degree of error. Generally speaking, plus or minus 10% is within a reasonable error range. Of course, the context in which the numerical value is used needs to be considered. For example, the particle size of the active ingredient, the numerical value is the error change after measurement does not exceed plus or minus 10%, which can be plus or minus 9%, plus or minus 8%, plus or minus 7%, plus or minus 6%, plus or minus 5%, plus or minus 4%, plus or minus 3%, plus or minus 2% or plus or minus 1%, preferably plus or minus 5%.

[0041] The pharmaceutically acceptable salts of the compounds of the present invention or their salts may be selected from inorganic salts or organic salts, including "acid" addition salts and "base" addition salts. For example, salts formed by acid-base reaction with a basic group (amino group), wherein the acid includes an organic acid or an inorganic acid.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. Compared with the prior art, the present invention uses cytidine as a raw material, utilizes a condensation reagent and an alkaline substance to synthesize cyclocytidine under mild conditions, and then generates arabinoside from cyclocytidine, thereby avoiding the use of highly toxic dehydrating agents and complex synthesis steps, and can directly obtain a high-purity arabinoside product, which is also safer.

[0044] 2. The method for preparing cytarabine provided by the present invention significantly improves the yield and purity of the reaction by optimizing the molar ratio of cytidine to the condensation reagent and the base, the molar ratio of cyclocytidine to chloroacetic acid chloride, and the selection of the reaction solvent.

[0045] 3. The present invention uses more environmentally friendly solvents and reagents, such as tetrahydrofuran, methanol, ethyl acetate, etc., which are more environmentally friendly than traditional solvents and dehydrating agents. By optimizing the reaction conditions, the emission of harmful waste gas and wastewater is reduced, which meets the basic requirements of green chemistry. This advantage makes the preparation process of the present invention more sustainable, reduces the impact on the environment during the production process, and also reduces the risk to the health of the staff, making the preparation safer.

[0046] 4. The present invention also provides a method for purifying cytarabine, a method for preparing cytarabine acetate, and a method for purifying cytarabine acetate. The finished products have high purity and extremely low single impurity content, thereby ensuring the high quality of cytarabine and cytarabine acetate. In the prior art, low-purity crude cytarabine is usually purified, that is, the finished product is re-purified. Different from the prior art, the present invention selects and optimizes the intermediate product compound C. The compound C prepared by the present invention is easy to purify, and the chloroacetyl group in the structure is easy to leave. The purified compound C is converted into cytarabine under corresponding conditions, and the converted cytarabine can directly have high purity.

[0047] Furthermore, the prior art faces multiple technical difficulties in purifying intermediate products, including the similarity between the intermediate products and impurities, the influence of reaction by-products, poor chemical stability, limited applicability of conventional purification methods, low purification efficiency and long cycle, and high cost. Therefore, the present invention can also be said to provide a new technical route for purifying cytarabine or a new technical route for directly obtaining high-purity cytarabine, which solves the problem that the prior art cannot effectively purify the intermediate products. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] Unless otherwise specified, the experimental methods used below are conventional methods. The equipment, materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified. The principles or mechanisms of equipment that can be purchased through commercial channels are well known and therefore will not be elaborated on.

[0050] The detection method of the following embodiment is:

[0051] The structures of the compounds were determined by nuclear magnetic resonance (NMR) and / or mass spectrometry (MS).

[0052] NMR shift (δ) is given in units of 10-6 (ppm). NMR measurements were performed using a Bruker AVANCE-400 nuclear magnetic spectrometer, and the measurement solvent was deuterated dimethyl sulfoxide (d6-DMSO).

[0053] MS was determined using a Waters Micromass Quattro micro API triple quadrupole mass spectrometer in positive / negative ion mode with a mass scan range of 120-1300.

[0054] HPLC column: YMC-Pack ODS-A (3 μm, 4.6 mm x 150 mm), mobile phase: gradient elution, mobile phase A: sodium acetate / acetic acid solution with pH = 6.5, i.e., a mixture of sodium acetate and acetic acid; mobile phase B: methanol, detection wavelength 278 nm.

[0055] Example 1

[0056] The synthetic route of cyclocytidine (compound B) is as follows:

[0057]

[0058] The synthesis steps of cyclocytidine are as follows: 50.0 g (205 mmol) of cytidine (compound A) is dissolved in 200 mL of dimethylformamide, 42.0 g of trichlorotriazine and 20.7 g of triethylamine are added, and the mixture is heated to 100° C. The reaction is completed by monitoring by TLC, and the product is precipitated and filtered. The filter cake is slurried with methanol for 3-4 hours and then filtered again to obtain 44.1 g of cyclocytidine with a yield of 95.2%.

[0059] Example 2

[0060] The synthetic route of compound C is as follows:

[0061]

[0062] The synthesis steps of compound C are as follows: 40.0 g (177 mmol) of cyclocytidine (prepared in Example 1) was dissolved in 200 mL of tetrahydrofuran, and 20.9 g of chloroacetic acid chloride and 14.7 g (186 mmol) of pyridine were added in sequence, and the reaction was maintained at 20°C. After the reaction was completed by TLC monitoring, water was added to quench the reaction, and the organic phase was separated. The organic phase was then washed with saturated brine and saturated sodium bicarbonate solution, dried in vacuo at 40-50°C, and concentrated to obtain 49.2 g of the target product (compound C), with a yield of 92.9%.

[0063] Further detection of the target product (Compound C) was performed according to the detection method given above, and the results were:

[0064] MS determination: MS (ESI): m / z 302.05 [M+1] + .

[0065] Further purify the target product (Compound C): 49 g of the product (Compound C) obtained in the previous step was added to methanol / ethyl acetate (V:V=1:5), heated to 50-60°C and stirred for 1-2 hours, then cooled to room temperature, continued to stir and slurry for 2 hours, filtered, washed with methanol / water (V:V=1:10) solvent, filtered, and dried to obtain 47.5 g of the target product, with a purity of 98.9% detected by HPLC, and a single impurity content of less than 0.8%. Wherein, V:V is a volume ratio, for example: methanol / ethyl acetate (V:V=1:5) means that the volume ratio of methanol to ethyl acetate is 1:5, and other references refer to this meaning.

[0066] Example 3

[0067] The synthetic route of cytarabine (compound D) is as follows:

[0068]

[0069] Synthesis steps of cytarabine acetate: Take 40g of the aforementioned 98.9% pure product (purified compound C), add it to 100ml methanol solution, then add 28g of concentrated ammonia water dropwise, heat to 60-70°C for reaction for 1-2h, cool, adjust the solution pH to 4-5 with 1M acetic acid solvent, concentrate under reduced pressure, add 50ml-70ml of isopropanol, filter to obtain 36.38g of crude cytarabine acetate, with a yield of 90.4%.

[0070] The synthesis steps of cytarabine are as follows: 35g of cytarabine acetate is added to 150ml of isopropanol, heated at 40°C and stirred for 2h, cooled to room temperature, slurried for 4h, and filtered to obtain a solid. Then, it is added to 80ml of water, sodium bicarbonate solvent is added to adjust the pH to 6-7, stirred for 1h, 70ml of isopropanol solvent is added dropwise, filtered, and vacuum dried at 40-50°C to obtain 26.7g of cytarabine, with a yield of 95%. HPLC detection is 99.2%, and the single impurity content is less than 0.1%.

[0071] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing cytarabine, characterized in that: The steps include: Cytidine reacts in the presence of a condensation reagent and a base to form cyclocytidine, cyclocytidine reacts with chloroacetic acid chloride to form compound C, and compound C reacts in the presence of ammonia water to form cytarabine.

2. The method for preparing cytarabine according to claim 1, characterized in that: The condensation reagent includes trichloro-s-triazine; the base includes triethylamine or N,N-diisopropylethylamine.

3. The method for preparing cytarabine according to claim 1, characterized in that: The molar ratio of cytidine to the condensation reagent is 1:0.9 to 1:

2.

4. The method for preparing cytarabine according to claim 1, characterized in that: The molar ratio of cytidine to base is 1:1 to 1:

4.

5. The method for preparing cytarabine according to claim 1, characterized in that: Cyclic cytidine is reacted with trichloro-s-triazine and triethylamine in N,N-dimethylformamide solvent at room temperature to form cyclocytidine.

6. The method for preparing cytarabine according to claim 1, characterized in that: Cyclocytidine reacts with chloroacetic acid chloride under organic base conditions to form compound C, wherein the organic base includes triethylamine or pyridine.

7. The method for preparing cytarabine according to claim 1, characterized in that: The molar ratio of cyclocytidine to chloroacetic acid chloride is 1:0.9-2.

8. The method for preparing cytarabine according to claim 1, characterized in that: Compound C is purified to obtain purified compound C, and the purified compound C reacts under ammonia conditions to form cytarabine or a pharmaceutically acceptable salt thereof; wherein the method for purifying compound C comprises: adding compound C to a pulping solution, heating and stirring, pulping after cooling, washing, and drying to obtain purified compound C; the pulping solution comprises at least one of methanol and ethyl acetate.

9. The method for preparing cytarabine according to claim 1, characterized in that: Compound C forms cytarabine acetate under the conditions of ammonia and acetic acid solution.

10. The method for preparing cytarabine according to claim 1, characterized in that: The synthetic route is as follows: 。

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