Preparation method of nafamostat mesylate

Abstract

The invention relates to the technical field of compound preparation, and particularly discloses a preparation method of nafamostat mesylate. The method comprises the steps that 6-amidinyl-2-naphthol mesylate and p-guanidinobenzoic acid hydrochloride serve as raw materials and are subjected to a condensation reaction in the presence of an impurity inhibitor to obtain a condensation product, DMSO or DMF serves as a solvent for the condensation reaction, CDI serves as a condensing agent, and methanesulfonic acid serves as the impurity inhibitor; then mixing the obtained condensation product with a sodium bicarbonate aqueous solution, stirring and crystallizing to obtain nafamostat carbonate; the preparation method comprises the following steps: mixing nafamostat carbonate with methanesulfonic acid in acetone to obtain a nafamostat mesylate crude product; when the condensation reaction is carried out, the raw materials and the impurity inhibitor are dissolved in a solvent for the condensation reaction, and then the condensing agent is added; the molar ratio of the impurity inhibitor to the 6-amidinyl-2-naphthol mesylate is (0.1-0.5): 1; the use amount of the solvent for the condensation reaction is 15-30 times of the mass of the 6-amidinyl-2-naphthol mesylate. The product prepared by the method is high in yield and high in purity.

Description

Technical Field

[0001] The invention relates to the technical field of compound preparation, in particular to a method for preparing nafamostat mesylate. Background Art

[0002] Nafamostat mesylate is a synthetic serine protease inhibitor with anticoagulant, anti-fibrinolytic and anti-platelet aggregation effects. Specifically, it has an enzyme inhibitory effect, and can selectively inhibit trypsin, kallikrein, plasmin, fibrinase and trypsin-like serine protease, and can also inhibit phospholipase A2 and α2-macroglobulin-bound trypsin. Nafamostat mesylate can also inhibit the increase in pancreatic enzyme activity caused by pancreatitis and the activity of enzymes entering the blood, can improve the reduction in the total amount of kininogen caused by kallikrein activation, and produce an anticoagulant effect.

[0003] In summary, nafamostat mesylate for injection has a strong and extensive inhibitory effect on trypsin, complement system, coagulation and fibrinolytic system and platelet aggregation, and does not affect the coagulation system in the patient's body. It provides patients with a more ideal medication option and has good application prospects.

[0004] In the prior art, the main method for synthesizing nafamostat mesylate is to prepare nafamostat mesylate by reacting p-guanidinobenzoic acid and 6-amidino-2-naphthol. This process has a low yield of finished products and is difficult to purify. The byproduct DCU of the condensation agent DCC is difficult to remove completely, which affects the product quality.

[0005] Based on the above status quo, it is necessary to further study the preparation process of nafamostat mesylate to overcome the shortcomings of the prior art. Summary of the invention

[0006] The invention provides an optimized process for preparing nafamostat mesylate, which can better avoid the generation of impurities in the preparation process.

[0007] The specific technical solutions of the present invention are as follows:

[0008] A preparation method of nafamostat mesylate, comprising: firstly using 6-amidino-2-naphthol mesylate and p-guanidinobenzoic acid hydrochloride as raw materials, and carrying out a condensation reaction in the presence of an impurity inhibitor to obtain a condensation product, wherein the solvent of the condensation reaction is DMSO or DMF, the condensation agent is CDI, and the impurity inhibitor is methanesulfonic acid; then, mixing the obtained condensation product with a sodium bicarbonate aqueous solution, stirring and crystallizing to obtain nafamostat carbonate; and mixing the obtained nafamostat carbonate with methanesulfonic acid in acetone to obtain a crude product of nafamostat mesylate;

[0009] When carrying out the condensation reaction, the 6-amidino-2-naphthol methanesulfonate, p-guanidinobenzoic acid hydrochloride and impurity inhibitor are first dissolved in the solvent of the condensation reaction, and then the condensation agent is added to carry out the condensation reaction;

[0010] The molar ratio of the impurity inhibitor to 6-amidino-2-naphthol methanesulfonate is (0.1-0.5):1; the amount of the solvent used in the condensation reaction is 15-30 times (preferably 22.5 times) the mass of 6-amidino-2-naphthol methanesulfonate.

[0011] The present invention has found through extensive research that, when preparing nafamostat mesylate, the conventional reaction solvent pyridine is used to produce a relatively large unknown impurity which is difficult to remove. After optimizing various conventional recrystallization methods, the impurity can be removed to a level of 0.2% to 0.3%, but it is still difficult to reach the limit required for pharmaceutical use (0.10%). In addition, the inventor has also conducted extensive investigations on reaction solution concentration, temperature, feed ratio, reaction time and other conditions under the conditions disclosed in the prior art (i.e., pyridine as the reaction solvent, DCC or EDCI as the condensing agent), but found that the unknown impurity cannot be removed.

[0012] In order to address the above problems, the present invention has further explored conventional nafamostat mesylate preparation conditions, condensation reaction system has been adjusted, specifically reaction solvent is changed to DMF or DMSO, condensing agent is changed to CDI (improved the conversion ratio of reaction, reduced by-product generation simultaneously, the by-product imidazoles of CDI can be thoroughly removed in the aftertreatment washing process, solved the problem of conventional DCC by-product DCU removal difficulty), now found that the generation amount of above-mentioned impurity is reduced, but still does not reach ideal effect.Afterwards, the inventor, through further analysis experiment, found that finally in the condensation reaction system, adding specific inhibitor can neither affect the carrying out of reaction, and suppresses the generation of above-mentioned impurity (this impurity can be suppressed within 0.06%).Then the inventor, through systematic process investigation, finally determined the new preparation technology of nafamostat.

[0013] Specifically during research and development, the present invention also found that the amount of impurity inhibitor methanesulfonic acid used directly affects the production of difficult-to-remove impurities. If the amount is too low, the inhibitory effect cannot be activated, and if the amount is too high, the main reaction will be inhibited and the yield will be reduced. The amount of reaction solvent used will also affect the amount of difficult-to-remove impurities generated. If the amount is too low, the reaction concentration will increase, and the amount of impurities generated will increase. Although too high an amount has no negative impact, it will increase costs. In addition, the feeding method of the condensation reaction is also very important. The conventional method of activating the substrate carboxylic acid and CDI first and then adding the substrate hydroxyl group cannot be used, otherwise the amount of difficult-to-remove impurities generated will increase. Ultimately, the process of the present invention can make the product purity and yield higher, save production costs, and facilitate industrial applications. See the flow diagram of the preparation route of the present invention. Figure 1 .

[0014] In the condensation reaction of the present invention, the molar ratio of 6-amidino-2-naphthol methanesulfonate, p-guanidinobenzoic acid hydrochloride and the condensation agent is 1:(1-1.2):(1.2-1.5), preferably 1:1:1.2; the reaction temperature of the condensation reaction is 0-30°C, and the reaction time is 1-2h.

[0015] The reaction time and reaction temperature of the present invention can be used to balance the yield and reduce the risk of increasing difficult-to-remove impurities.

[0016] Preferably, when carrying out the condensation reaction, the reactants and the inhibitor methanesulfonic acid are first added to a solvent to dissolve, and then the condensation agent is added at once at a controlled temperature of 0 to 30°C to carry out the reaction.

[0017] In the preparation method of the present invention, the condensation product and the sodium bicarbonate aqueous solution are mixed at 0-10°C, and the stirring crystallization is carried out at 0-10°C.

[0018] The sodium bicarbonate aqueous solution is a saturated sodium bicarbonate aqueous solution, and the amount of the saturated sodium bicarbonate aqueous solution is 0.5 to 1 times the mass of DMSO or DMF.

[0019] Preferably, after the condensation product is mixed with the sodium bicarbonate aqueous solution and stirred for crystallization, the process further comprises washing with water, wherein the amount of water used is 1 to 2 times the mass of the saturated sodium bicarbonate aqueous solution.

[0020] In the preparation method of the present invention, when nafamostat carbonate and methanesulfonic acid are mixed, the temperature is controlled to be 0-10°C, the amount of acetone used is 3-5 times (preferably 4 times) the mass of nafamostat carbonate, and the molar ratio of nafamostat carbonate to methanesulfonic acid is 1:(2-2.2), preferably 1:2.1.

[0021] The preparation method of the present invention further comprises the step of refining the crude product of nafamostat mesylate after obtaining it;

[0022] The refining method is as follows: the crude product of nafamostat mesylate is mixed with water, dissolved at 50-60° C., then mixed with acetone, cooled, and maintained at 0-10° C. for crystallization.

[0023] Preferably, in the refining, the amount of water used is 3-5 times (preferably 4 times) the mass of nafamostat carbonate, and the amount of acetone used is 18-30 times (preferably 24 times) the mass of nafamostat carbonate.

[0024] In the refining of the preparation method of the present invention, after crystallization, the steps of eluting with acetone and drying are also included; during eluting, the amount of acetone used is 2 to 4 times the mass of nafamostat carbonate, and the drying conditions are: vacuum drying at 40-50°C for 4-5h.

[0025] The preparation method of the present invention comprises:

[0026] (1) mixing and dissolving p-guanidinobenzoic acid hydrochloride, 6-amidino-2-naphthol methanesulfonate and an impurity inhibitor with a condensation reaction solvent, then adding a condensation agent at a temperature of 0 to 30° C., reacting at 0 to 30° C. for 1 to 2 hours, and after the reaction is completed, mixing with a saturated sodium bicarbonate aqueous solution at a temperature of 0 to 10° C., stirring and crystallizing at a temperature of 0 to 10° C., filtering, and washing with purified water to obtain nafamostat carbonate;

[0027] (2) dispersing the obtained nafamostat carbonate in acetone, adding methanesulfonic acid at a temperature of 0 to 10° C., then adding purified water, heating to 50 to 60° C. to dissolve, then adding acetone, cooling and maintaining the temperature at 0 to 10° C. to crystallize for 1 to 2 hours, filtering, eluting with acetone, and vacuum drying at 40 to 50° C. for 4 to 5 hours to obtain nafamostat mesylate.

[0028] The beneficial effects of the present invention are at least:

[0029] The method for preparing nafamostat mesylate of the present invention solves the problems of poor product purity and low yield in the existing process flow through process optimization, reduces production costs, obtains products with good quality and high yield, and is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The figure is a schematic diagram of the route flow of the preparation method of the present invention.

[0031] Figure 2 This is the detection chromatogram of the final product prepared by the method of Document 1 in the experimental example of the present invention.

[0032] Figure 3 This is the detection chromatogram of the final product prepared by the method of Document 2 in the experimental example of the present invention.

[0033] Figure 4 This is the NMR spectrum of the final product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that the following examples are provided only for the purpose of illustration and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0035] The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources. If no specific techniques or conditions are specified in the following examples, the techniques or conditions described in the literature in the field or the product instructions are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased through regular channels.

[0036] In the present invention, DCC refers to N,N'-dicyclohexylcarbodiimide, DCU refers to N,N'-dicyclohexylurea, CDI refers to N,N'-carbonyldiimidazole, EDCI refers to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, DMF refers to N,N-dimethylformamide, and DMSO refers to dimethyl sulfoxide.

[0037] Experimental example

[0038] This experimental example studied the conventional preparation method of nafamostat using pyridine as the reaction solvent and found that it produced a large unknown impurity. The specific preparation method and single impurity discovery process are as follows:

[0039] (1) Reference 1 "Synthesis of Nafamostat Mesylate" (Chen Baoquan, Zhao Yusong, Ouyang Jie, Ma Ning, Li Caiwen. Chinese Journal of Pharmaceutical Industry, 2007 (08): 545-546) reported the method, using anhydrous pyridine as the reaction solvent, p-guanidinobenzoic acid hydrochloride and 6-amidino-2-naphthol mesylate as raw materials, DCC as a condensation agent, DMAP as a catalyst, stirring at room temperature for 5 hours, precipitating a white solid, filtering, washing the filter cake with pyridine, adding water to stir and disperse, filtering to remove the by-product DCU, stirring the filtrate into a saturated sodium bicarbonate aqueous solution, precipitating a solid, filtering, suspending the filter cake in methanol, adding methanesulfonic acid dropwise in an ice bath, stirring at room temperature for 0.5 hours, adding ether, filtering, and recrystallizing with a mixed solvent of acetone and water to obtain Nafamostat Mesylate. Chromatographic detection showed that there was a large unknown impurity (peak time of about 28 minutes), the content of which was 5.1%. Specific chromatographic information is shown in Table 1, and the chromatogram is shown in Figure 2 .

[0040] Table 1

[0041] Peak Retention time area area% high Theoretical Plate Number (USP) Tailing Factor Resolution (USP) 1 5.637 10945 0.033 1320 9248 1.243 -- 2 7.626 16968 0.051 1647 11420 1.124 7.650 3 14.764 269567 0.812 36413 78289 1.159 28.752 4 16.277 54103 0.163 8694 127314 1.170 7.686 5 16.689 20072 0.060 3360 144333 1.160 2.304 6 17.940 37623 0.113 4791 104926 1.218 6.297 7 20.057 31081484 93.611 2887717 72046 1.267 8.137 8 22.703 4323 0.013 269 41633 1.319 7.113 9 24.594 12752 0.038 641 40140 1.473 4.041 10 28.282 1694935 5.105 71376 37060 0.866 6.837 total 33202771 100.000 3016229

[0042] (2) The method reported in reference 2 "Improvement of the Synthesis Process of p-guanidinobenzoic Acid Hydrochloride and Study on the Synthesis Process of Nafamostat Mesylate" (Zhao Yusong. Hebei Medical University, 2004) uses p-guanidinobenzoic acid hydrochloride and 6-amidino-2-naphthol methanesulfonate as raw materials. First, p-guanidinobenzoic acid hydrochloride is prepared into p-guanidinobenzoyl chloride hydrochloride in thionyl chloride, and then stirred with 6-amidino-2-naphthol methanesulfonate in pyridine in an ice bath for 1 hour, then stirred at room temperature overnight, added with ether, separated the oily substance, dispersed the oily substance in water, filtered, added the filtrate to a saturated sodium bicarbonate aqueous solution, precipitated the solid, filtered, washed with water, washed with acetone, added the filter cake to ethanol, added methanesulfonic acid, and then added with ether to obtain Nafamostat Mesylate. Chromatographic detection showed that there was a large unknown impurity (peak time of about 28 minutes), with a content of 4.9%. Specific chromatographic information is shown in Table 2, and the chromatogram is shown in Table 2. Figure 3 .

[0043] Table 2

[0044] Peak Retention time area Surface high Theoretical Plate Number (USP) Tailing Factor Resolution (USP) 1 5.661 10689 0.043 1347 10008 1.208 -- 2 7.690 45231 0.183 4350 11768 1.154 7.958 3 14.845 253360 1.024 34036 79903 1.171 28.990 4 16.329 84289 0.341 13238 124196 1.178 7.504 5 16.733 15285 0.062 2499 137425 1.182 2.210 6 18.008 35118 0.142 4199 94468 1.238 6.149 7 18.457 34635 0.140 3912 88749 1.127 1.859 8 20.133 23043435 93.094 2066633 70399 1.222 6.081 9 24.731 11022 0.045 499 31443 1.483 10.675 10 28.003 1219935 4.928 51094 38826 1.579 5.811 total 24752999 100.000 2181806

[0045] The present invention finds that the nafamostat mesylate prepared by two prior art methods respectively contains a large unknown impurity and cannot meet the high quality requirements.

[0046] This experimental example further studied the removal method of single impurities, as follows:

[0047] (1) It is proposed to remove the larger unknown impurities through refining. Specifically, based on the method in Reference 1, the refining solvent and the number of refining times are studied. The research results are shown in Table 3.

[0048] Table 3

[0049]

[0050] This experimental example examined different solvents, different mixed solvents, different ratios of mixed solvents, and different refining times, but none of them could remove the unknown impurities to less than 0.1%. The present invention further attempts to reduce the content of larger unknown impurities by controlling the reaction conditions.

[0051] (2) The condensation method using a condensing agent was used to reduce the content of large unknown impurities by optimizing the reaction conditions. The research was conducted based on the method in Reference 1. The research results are shown in Table 4.

[0052] Table 4

[0053]

[0054]

[0055]

[0056] The chromatographic detection method used in the present invention is as follows:

[0057] Test solution: Take about 10 mg of the product, weigh accurately, place in a 10 ml volumetric flask, add methanol to dissolve and dilute to the scale, shake well.

[0058] Chromatographic conditions: octadecylsilane bonded silica gel was used as filler; 6.07 g sodium heptane sulfonate and 6 ml acetic acid were dissolved in water and diluted to 1000 ml as mobile phase A; acetonitrile was used as mobile phase B, and gradient elution was performed according to Table 5 below; column temperature was 30°C; detection wavelength was 260 nm; flow rate was 1.0 ml / min; injection volume was 10 μl.

[0059] Table 5

[0060]

[0061] Finally, through the above experiments, the present invention found that the above-mentioned single impurities found in the conventional preparation method can neither be removed by adjusting the reaction conditions nor achieve an ideal removal effect by recrystallization and the like.

[0062] Example 1

[0063] Step 1: Preparation of Nafamostat Carbonate

[0064] First, add 282.32g of 6-amidino-2-naphthol methanesulfonate, 215.64g of p-guanidinobenzoic acid hydrochloride, 9.61g of methanesulfonic acid, and 4.24kg of DMSO into a 10L reactor and stir to dissolve. Then, add 194.58g of CDI at a temperature of 0-2°C, and react at 0°C for 1h. After the reaction is completed, control the temperature at 0-10°C, add 2.82kg of saturated sodium bicarbonate aqueous solution, control the temperature at 0°C, stir and crystallize for 0.5h, filter, and wash with 2.82kg of purified water to obtain nafamostat carbonate (with a yield of 100%), which is directly used in the next step.

[0065] Step 2: Preparation of Nafamostat Mesylate

[0066] The nafamostat carbonate obtained in the previous step was dispersed in 1885.72g of acetone, and 201.60g of methanesulfonic acid was added at a temperature of 0-10°C, and then 1885.72g of purified water was added, and the temperature was raised to 55°C for dissolution, and then 8.54kg of acetone was added, and the temperature was lowered and kept at 0°C for crystallization for 1.5h, filtered, rinsed with 948.8g of acetone, and vacuum dried at 45°C for 4.5h to obtain 404.68g of nafamostat mesylate. In this embodiment, it was confirmed by nuclear magnetic resonance that the synthesized product was nafamostat mesylate (see the nuclear magnetic spectrum for the Figure 4 ). Yield: 74.99%, HPLC purity: 99.858%, maximum single impurity: 0.07%.

[0067] Example 2

[0068] Step 1: Preparation of Nafamostat Carbonate

[0069] First, add 282.32g of 6-amidino-2-naphthol methanesulfonate, 215.64g of p-guanidinobenzoic acid hydrochloride, 48.00g of methanesulfonic acid, and 8.47kg of DMSO into a 20L reactor and stir to dissolve. Then, add 194.58g of CDI at a temperature of 25-30°C, and react at 30°C for 1h. After the reaction is completed, control the temperature at 0-10°C, add 8.47kg of saturated sodium bicarbonate aqueous solution, control the temperature at 10°C, stir and crystallize for 0.5h, filter, and wash with 16.94kg of purified water to obtain nafamostat carbonate (with a yield of 100%), which is directly used in the next step.

[0070] Step 2: Preparation of Nafamostat Mesylate

[0071] The nafamostat carbonate obtained in the previous step was dispersed in 1885.72 g of acetone, and the temperature was controlled at 0-10°C. 201.60 g of methanesulfonic acid was added, and then 1885.72 g of purified water was added, and the temperature was raised to 60°C to dissolve, and then 14.14 kg of acetone was added, and the temperature was lowered and maintained at 10°C for crystallization for 2 h, filtered, rinsed with 1.88 kg of acetone, and vacuum dried at 40°C for 5 h to confirm that 410.12 g of nafamostat mesylate was obtained, with a yield of 76.01%, HPLC purity: 99.804%, and maximum single impurity: 0.07%.

[0072] Example 3

[0073] Step 1: Preparation of Nafamostat Carbonate

[0074] First, add 282.32g of 6-amidino-2-naphthol methanesulfonate, 215.64g of p-guanidinobenzoic acid hydrochloride, 28.83g of methanesulfonic acid, and 6.35kg of DMSO into a 10L reactor and stir to dissolve. Then, add 194.58g of CDI at a temperature of 12-15°C, and react at 15°C for 2h. After the reaction is completed, control the temperature at 0-10°C, add 4.76kg of saturated sodium bicarbonate aqueous solution, control the temperature at 5°C, stir and crystallize for 0.5h, filter, and wash with 7.14kg of purified water to obtain nafamostat carbonate (with a yield of 100%), which is directly used in the next step.

[0075] Step 2: Preparation of Nafamostat Mesylate

[0076] Disperse the nafamostat carbonate obtained in the previous step into 1885.72 g of acetone, control the temperature at 0-10°C, add 201.60 g of methanesulfonic acid, then add 1885.72 g of purified water, raise the temperature to 50°C to dissolve, then add 11.3 kg of acetone, cool and maintain at 5°C for crystallization for 1 hour, filter, rinse with 1 L of acetone, and vacuum dry at 50°C for 4 hours to confirm that 412.88 g of nafamostat mesylate is obtained, with a yield of 76.52%, HPLC purity: 99.851%, and maximum single impurity: 0.07%.

[0077] Example 4

[0078] Step 1: Preparation of Nafamostat Carbonate

[0079] First, add 282.32g of 6-amidino-2-naphthol methanesulfonate, 215.64g of p-guanidinobenzoic acid hydrochloride, 28.83g of methanesulfonic acid, and 6.35kg of DMF into a 10L reactor and stir to dissolve. Then, add 194.58g of CDI at a temperature of 12-15°C, and react at 15°C for 2h. After the reaction is completed, control the temperature at 0-10°C, add 4.76kg of saturated sodium bicarbonate aqueous solution, control the temperature at 5°C, stir and crystallize for 0.5h, filter, and wash with 7.14kg of purified water to obtain nafamostat carbonate (with a yield of 100%), which is directly used in the next step.

[0080] Step 2: Preparation of Nafamostat Mesylate

[0081] Disperse the nafamostat carbonate obtained in the previous step into 1885.72 g of acetone, control the temperature at 0-10°C, add 201.60 g of methanesulfonic acid, then add 1885.72 g of purified water, raise the temperature to 50°C to dissolve, then add 11.3 kg of acetone, cool and maintain 5°C for crystallization for 1 hour, filter, rinse with 1 L of acetone, and vacuum dry at 50°C for 4 hours to confirm that 406.21 g of nafamostat mesylate is obtained, with a yield of 75.28%, HPLC purity: 99.790%, and maximum single impurity: 0.07%.

[0082] Comparative Example 1

[0083] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 1, except that in step 1, EDCI is used as a condensing agent in an amount of 230.04 g, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 15.38%, HPLC purity is 99.528%, and the maximum single impurity is 0.06%.

[0084] Comparative Example 2

[0085] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 1, except that pyridine is used instead of DMSO as the reaction solvent in step 1, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 50.46%, HPLC purity is 98.074%, and the maximum single impurity is 1.5%.

[0086] Comparative Example 3

[0087] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 1, except that in step 1, dimethylacetamide (DMA) is used instead of DMSO as the reaction solvent, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 65.51%, HPLC purity: 99.637%, and the maximum single impurity is 0.07%.

[0088] Comparative Example 4

[0089] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 1, except that in step 1, sulfuric acid is used as an impurity inhibitor in an amount of 9.81 g, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 12.29%, HPLC purity: 99.752%, and the maximum single impurity is 0.08%.

[0090] Comparative Example 5

[0091] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 1, except that in step 1, the feeding method is changed, p-guanidinobenzoic acid hydrochloride, methanesulfonic acid and CDI are first mixed and dissolved in DMSO for carboxyl activation, and then 6-amidino-2-naphthol mesylate is added at a temperature of 0 to 2°C, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 75.35%, HPLC purity: 99.420%, and maximum single impurity: 0.13%.

[0092] Comparative Example 6

[0093] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 2, except that in step 1, the amount of impurity inhibitor added is changed to 57.67 g, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 62.82%, HPLC purity: 99.789%, and maximum single impurity: 0.07%.

[0094] Comparative Example 7

[0095] This comparative example provides a preparation method of nafamostat mesylate, which is basically the same as the method in Example 1, except that in step 1, the amount of the solvent used in the condensation reaction is changed to 3.67 kg, and other conditions remain unchanged. Finally, the yield of nafamostat mesylate is 76.21%, HPLC purity: 99.518%, and maximum single impurity: 0.15%.

[0096] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing nafamostat mesylate, characterized in that, First, 6-amidino-2-naphthol methanesulfonate and p-guanidinobenzoic acid hydrochloride are used as raw materials, and a condensation reaction is carried out in the presence of an impurity inhibitor to obtain a condensation product, wherein the solvent of the condensation reaction is DMSO or DMF, the condensation agent is CDI, and the impurity inhibitor is methanesulfonic acid; then, the obtained condensation product is mixed with a sodium bicarbonate aqueous solution, stirred and crystallized to obtain nafamostat carbonate; in acetone, the obtained nafamostat carbonate is mixed with methanesulfonic acid to obtain a crude product of nafamostat mesylate; When carrying out the condensation reaction, the 6-amidino-2-naphthol methanesulfonate, p-guanidinobenzoic acid hydrochloride and impurity inhibitor are first dissolved in the solvent of the condensation reaction, and then the condensation agent is added to carry out the condensation reaction; The molar ratio of the impurity inhibitor to 6-amidino-2-naphthol methanesulfonate is (0.1-0.5):1; the amount of the solvent used in the condensation reaction is 15-30 times the mass of 6-amidino-2-naphthol methanesulfonate.

2. The preparation method according to claim 1, characterized in that: In the condensation reaction, the molar ratio of 6-amidino-2-naphthol methanesulfonate, p-guanidinobenzoic acid hydrochloride and the condensation agent is 1:(1-1.2):(1.2-1.5); the reaction temperature of the condensation reaction is 0-30°C, and the reaction time is 1-2h.

3. The preparation method according to claim 1 or 2, characterized in that: The mixing of the condensation product and the sodium bicarbonate aqueous solution is carried out at 0-10°C, and the stirring crystallization is carried out at 0-10°C.

4. The preparation method according to claim 3, characterized in that: The sodium bicarbonate aqueous solution is a saturated sodium bicarbonate aqueous solution, and the amount of the saturated sodium bicarbonate aqueous solution is 0.5 to 1 times the mass of DMSO or DMF.

5. The preparation method according to claim 3 or 4, characterized in that: The method further comprises the step of washing with water after the condensation product is mixed with the sodium bicarbonate aqueous solution and stirred for crystallization, wherein the amount of water used is 1 to 2 times the mass of the saturated sodium bicarbonate aqueous solution.

6. The preparation method according to any one of claims 1 to 5, characterized in that: When nafamostat carbonate and methanesulfonic acid are mixed, the temperature is controlled at 0-10 DEG C, the amount of acetone used is 3-5 times the mass of nafamostat carbonate, and the molar ratio of nafamostat carbonate to methanesulfonic acid is 1:(2-2.2).

7. The preparation method according to any one of claims 1 to 6, characterized in that: The preparation method further comprises the step of refining the crude product of nafamostat mesylate after obtaining it; The refining method is as follows: the crude product of nafamostat mesylate is mixed with water, dissolved at 50-60° C., then mixed with acetone, cooled, and maintained at 0-10° C. for crystallization.

8. The preparation method according to claim 7, characterized in that: In the refining, the amount of water used is 3-5 times the mass of nafamostat carbonate, and the amount of acetone used is 18-30 times the mass of nafamostat carbonate.

9. The preparation method according to claim 7 or 8, characterized in that: The refining process further comprises the steps of rinsing with acetone and drying after crystallization; during rinsing, the amount of acetone used is 2 to 4 times the mass of nafamostat carbonate, and the drying conditions are: vacuum drying at 40-50° C. for 4-5 hours.

10. The preparation method according to any one of claims 1 to 9, characterized in that: include: (1) mixing and dissolving p-guanidinobenzoic acid hydrochloride, 6-amidino-2-naphthol methanesulfonate and an impurity inhibitor with a condensation reaction solvent, then adding a condensation agent at a temperature of 0 to 30° C., reacting at 0 to 30° C. for 1 to 2 hours, and after the reaction is completed, mixing with a saturated sodium bicarbonate aqueous solution at a temperature of 0 to 10° C., stirring and crystallizing at a temperature of 0 to 10° C., filtering, and washing with purified water to obtain nafamostat carbonate; (2) dispersing the obtained nafamostat carbonate in acetone, adding methanesulfonic acid at a temperature of 0 to 10° C., then adding purified water, heating to 50 to 60° C. to dissolve, then adding acetone, cooling and maintaining the temperature at 0 to 10° C. to crystallize for 1 to 2 hours, filtering, eluting with acetone, and vacuum drying at 40 to 50° C. for 4 to 5 hours to obtain nafamostat mesylate.

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