Method for preparing nafamostat mesylate

Abstract

The invention relates to the technical field of compound synthesis, and particularly discloses a method for preparing nafamostat mesylate. The preparation method comprises the following steps: (1) preparing 6-imino ester-2-naphthol hydrochloride; (2) preparing 6-imino ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride in a reaction solvent DMF (Dimethyl Formamide) or DMSO (Dimethyl Sulfoxide); (3) preparing nafamostat carbonate in a reaction solvent DMF (Dimethyl Formamide) or DMSO (Dimethyl Sulfoxide); and (4) preparing nafamostat mesylate. The nafamostat mesylate is prepared by the method disclosed by the invention, a high-quality and high-yield product can be obtained, and the method is suitable for industrial popularization.

Description

Technical Field

[0001] The invention relates to the technical field of compound synthesis, 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. The specific characteristics of the action are as follows: 1. Enzyme inhibition: This drug has a strong selective inhibitory effect on trypsin-like serine proteases such as trypsin, kallikrein (angiokalogenin), plasmin, fibrinase, and CL-r and CL-s of the classical pathway of the complement system; it also has an inhibitory effect on phospholipase A2. In vitro, it also has an inhibitory effect on trypsin bound to α2-macroglobulin. 2. Effect on experimental acute pancreatitis: Intravenous infusion of this drug in rats and rabbits can inhibit the increase in pancreatic enzyme activity caused by pancreatitis and the activity of enzymes entering the blood, and reduce the mortality rate in various experimental pancreatitis caused by retrograde injection of trypsin, enterokinase and endotoxin through the pancreatic duct. 3. Effect on the kallikrein-kinin system: Giving this drug to patients with pancreatitis can improve the reduction in the total amount of kininogen caused by the activation of kallikrein. It is used to improve the symptoms of acute pancreatitis, acute deterioration of chronic pancreatitis, acute pancreatitis after pancreatography, traumatic pancreatitis, acute pancreatitis after surgery, etc. 4. Effects on blood coagulation and fibrinolysis system: This drug produces anticoagulant effect by inhibiting fibrinase and coagulation factors XIIa and Xa. In vitro experiments also found that this drug can inhibit platelet aggregation. In animal experiments, intravenous administration of this drug can prolong the activated partial thromboplastin (thrombin) time of rabbits and the fibrin clot dissolution time activated by urokinase. Since heparin increases the risk of bleeding, this drug can be used as a substitute for heparin. 5. Effects on the complement system: For guinea pigs with systemic Forsman heterophilic shock caused by intravenous injection of hemolysin, oral and intravenous administration of this drug can prolong their lives.

[0003] In general, nafamostat mesylate for injection is a broad-spectrum and potent serine protease inhibitor. It exerts its pharmacological effects by reversibly inhibiting trypsin-like serine proteases, and has a strong and extensive inhibitory effect on trypsin, complement system, coagulation fibrinolytic system and platelet aggregation. Due to its short half-life in vivo, when used as an anticoagulant during extracorporeal blood circulation, it only exerts an anticoagulant effect in the extracorporeal circulation pathway without affecting the coagulation system in the patient's body. Therefore, it is particularly suitable for patients with bleeding tendency. It is the first choice anticoagulant for patients with bleeding tendency undergoing extracorporeal circulation (including hemodialysis, CRRT, plasma exchange, ECMO, etc.), providing patients with a more reasonable choice and having broad application prospects.

[0004] In the prior art, there are two main methods for synthesizing nafamostat mesylate: the first method is to react 4-guanidinobenzoic acid with 6-amidino-2-naphthol to generate nafamostat; the second method is to synthesize nafamostat from 4-guanidinobenzoyl chloride and 6-amidino-2-naphthol. Both methods produce large by-products in the nafamostat prepared by these two methods, which need to be refined for removal multiple times, which is not conducive to industrial production and product quality assurance.

[0005] Based on the above situation, it is urgent to propose a new preparation process of nafamostat mesylate to overcome the shortcomings of the existing technology and prepare high-purity nafamostat mesylate. Summary of the invention

[0006] One of the purposes of the present invention is to provide a process for preparing nafamostat mesylate with high product purity and high yield.

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

[0008] A method for preparing nafamostat mesylate, comprising:

[0009] (1) preparing 6-iminoester-2-naphthol hydrochloride;

[0010] (2) preparing 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride in a reaction solvent DMF (N,N-dimethylformamide) or DMSO (dimethyl sulfoxide);

[0011] (3) preparing nafamostat carbonate in a reaction solvent, DMF or DMSO;

[0012] (4) Preparation of nafamostat mesylate.

[0013] The present invention has found through a large number of experimental investigations that the use of pyridine as a reaction solvent reported in the literature for the preparation of nafamostat will produce a large unknown impurity that is difficult to remove. By trying 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 of 0.10% required for pharmaceutical use. In this regard, the inventor has also conducted a large number of investigations on the reaction solution concentration, reaction temperature, feed ratio, reaction time, etc. under the conditions disclosed in the prior art, that is, pyridine is used as the reaction solvent and DCC or EDCI is used as the condensation agent, but the unknown impurity cannot be removed.

[0014] In order to solve this problem, the present invention improves the preparation method of nafamostat mesylate, redesigns the reaction route, changes the intermediate 6-amidino-2-naphthol and 6-amidino-2-naphthol mesylate commonly used in the prior art method for preparing nafamostat mesylate to 6-iminoester-2-naphthol hydrochloride, and combines the selection of a specific reaction solvent to make the reaction conditions in the route mild, with fewer side reactions, and the obtained nafamostat mesylate has a higher purity, thus overcoming the defects of the prior art. See the schematic diagram of the preparation route of the present invention for details. Figure 1 .

[0015] In step (1) of the method of the present invention, the 6-iminoester-2-naphthol hydrochloride is 6-iminomethyl ester-2-naphthol hydrochloride or 6-iminoethyl ester-2-naphthol hydrochloride; when 6-iminomethyl ester-2-naphthol hydrochloride is generated, 6-cyano-2-naphthol, anhydrous methanol and acetyl chloride are reacted; when 6-iminoethyl ester-2-naphthol hydrochloride is generated, 6-cyano-2-naphthol, anhydrous ethanol and acetyl chloride are reacted;

[0016] In step (2), the 6-iminoester-2-naphthol hydrochloride prepared in step (1) is reacted with p-guanidinobenzoic acid hydrochloride in DMF or DMSO in the presence of a condensing agent to prepare 6-iminoester-naphthalene-2-yl-4-guanidinobenzoate hydrochloride;

[0017] In step (3), the 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride prepared in step (2) is reacted with ammonium carbonate in DMF or DMSO to prepare nafamostat carbonate;

[0018] In step (4), the nafamostat carbonate prepared in step (3) is reacted with methanesulfonic acid in acetone to prepare nafamostat mesylate.

[0019] The 6-iminoester-2-naphthol hydrochloride in step (1) of the present invention can be 6-iminomethyl ester-2-naphthol hydrochloride (Formula 1), or 6-iminoethyl ester-2-naphthol hydrochloride (Formula 2). Correspondingly, in step (3), 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride can be 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride (Formula 3), or 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride (Formula 4).

[0020]

[0021] In step (1) of the method of the present invention, when generating 6-iminomethyl ester-2-naphthol hydrochloride, the molar ratio of 6-cyano-2-naphthol: acetyl chloride: anhydrous methanol is 1: (4-10): (10-24), preferably 1: 6: 15; when generating 6-iminoethyl ester-2-naphthol hydrochloride, the molar ratio of 6-cyano-2-naphthol: acetyl chloride: anhydrous ethanol is 1: (4-10): (10-24), preferably 1: 6: 20;

[0022] The reaction temperature in step (1) is 10-30°C, preferably 20-30°C.

[0023] In step (2) of the method of the present invention, the 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride is 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride or 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride; the condensing agent is CDI, DCC or EDCI; and the reaction temperature in step (2) is 10 to 30°C.

[0024] In step (3) of the method of the present invention, when 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride is used as the raw material, the molar ratio of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride to ammonium carbonate is 1:(0.5-1);

[0025] When 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride is used as the raw material, the molar ratio of 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride to ammonium carbonate is 1:(0.5-1), preferably 1:0.8;

[0026] The reaction temperature in step (3) is 20-30°C.

[0027] In step (4) of the method of the present invention, the reaction of nafamostat carbonate and methanesulfonic acid is carried out at 0-10°C.

[0028] The method of the present invention comprises:

[0029] (1) Add acetyl chloride dropwise to anhydrous methanol or anhydrous ethanol under stirring and temperature control at 0 to 10°C, stir at 0 to 10°C for 1 to 2 hours after the addition is complete, then add 6-cyano-2-naphthol, react at 10 to 30°C for 12 to 15 hours, then add methyl tert-butyl ether, stir and crystallize at 0 to 10°C for 1 to 2 hours to obtain 6-iminoester-2-naphthol hydrochloride;

[0030] (2) dissolving p-guanidinobenzoic acid hydrochloride and 6-iminoester-2-naphthol hydrochloride in DMF or DMSO with stirring, adding a condensing agent at a temperature of 10 to 30° C., and reacting at 10 to 30° C. for 1 to 2 hours to obtain a DMF or DMSO solution of 6-iminoester-naphthalene-2-yl-4-guanidinobenzoate hydrochloride;

[0031] (3) In a DMF or DMSO solution of 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride, add ammonium carbonate in batches at a temperature of 20 to 30° C., react at 20 to 30° C. for 4 to 5 hours, add purified water, control the temperature at 0 to 10° C., stir and crystallize for 1 to 2 hours, and obtain nafamostat carbonate;

[0032] (4) Dispersing 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 to 0 to 10° C. to crystallize for 1 to 2 hours, and obtaining nafamostat mesylate.

[0033] In step (1) of the method of the present invention, during crystallization, the amount of methyl tert-butyl ether added is 10 to 20 times the mass of 6-cyano-2-naphthol; after crystallization, the method further includes the steps of filtering, eluting with methyl tert-butyl ether, and drying; the drying conditions are: drying under reduced pressure at 30 to 40° C. for 4 to 6 hours.

[0034] In step (2) of the method of the present invention, the molar ratio of p-guanidinobenzoic acid hydrochloride to 6-iminoester-2-naphthol hydrochloride is 1:(0.9-1.1); the mass ratio of p-guanidinobenzoic acid hydrochloride to DMF or DMSO is 1:(14.8-30); and the molar ratio of p-guanidinobenzoic acid hydrochloride to the condensing agent is 1:(1.2-1.6).

[0035] The present invention has found that reducing the concentration of the reactants in step (2) can help reduce the generation of impurities.

[0036] In step (3) of the method of the present invention, during crystallization, the amount of purified water added is 0.5 to 1 times the mass of DMF or DMSO, and after crystallization, the steps of filtering and washing with purified water are also included.

[0037] In step (4) of the method of the present invention, the mass ratio of nafamostat carbonate to acetone is 1:(3-5); when forming the salt, the molar ratio of nafamostat carbonate to methanesulfonic acid is 1:(2.0-2.2);

[0038] During crystallization, the amount of purified water added is 3-5 times the mass of nafamostat carbonate, and the amount of acetone added is 18-30 times the mass of nafamostat carbonate;

[0039] After crystallization, the process also includes filtering, rinsing with acetone, and drying; the drying conditions are: vacuum drying at 40-50° C. for 4-5 hours.

[0040] The beneficial effects of the present invention are at least:

[0041] The nafamostat mesylate prepared by the method of the invention has high purity and high yield, does not require complicated impurity removal steps, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The schematic diagram of the preparation route of the method of the present invention is shown in FIG. 1 , wherein R is methyl or ethyl.

[0043] 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.

[0044] 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.

[0045] Figure 4 The mass spectrum of the final product prepared in Example 1 of the present invention is shown in FIG.

[0046] Figure 5 This is the NMR spectrum of the final product prepared in Example 1 of the present invention.

[0047] Figure 6 This is the mass spectrum of the final product prepared in Example 4 of the present invention.

[0048] Figure 7 This is the NMR spectrum of the final product prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0049] 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.

[0050] 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.

[0051] In the present invention, DCC refers to N,N'-dicyclohexylcarbodiimide, CDI refers to N,N'-carbonyldiimidazole, and EDCI refers to 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0052] Experimental example

[0053] This experimental example studied the preparation method of nafamostat using pyridine as a reaction solvent reported in the literature and found that it produced a large unknown impurity. The specific preparation method and single impurity discovery process are as follows:

[0054] (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 method, using anhydrous pyridine as reaction solvent, p-guanidinobenzoic acid hydrochloride and 6-amidino-2-naphthol mesylate as raw materials, DCC as condensation agent, DMAP as catalyst, stirring at room temperature for 5 hours, precipitating white solid, filtering, washing the filter cake with pyridine, adding water and stirring to disperse, filtering to remove by-product DCU, stirring the filtrate into saturated sodium bicarbonate aqueous solution, precipitating 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 acetone water mixed solvent to obtain Nafamostat Mesylate. Chromatographic detection showed that a large unknown impurity with a peak time of about 28 minutes was present, with a content of 5.1%. Specific chromatographic information is shown in Table 1, and the chromatogram is shown in Figure 2 .

[0055] Table 1

[0056] 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

[0057] The chromatographic detection method is as follows:

[0058] 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.

[0059] 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 2 below; column temperature was 30°C; detection wavelength was 260 nm; flow rate was 1.0 ml / min; injection volume was 10 μl.

[0060] Table 2

[0061]

[0062] (2) The method reported in reference 2 "Improved Synthesis of p-guanidinobenzoic Acid Hydrochloride and Study on Synthesis 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. After the above-mentioned chromatographic detection method, a large unknown impurity with a peak time of about 28 minutes was present, with a content of 4.9%. See Table 3 for specific chromatographic information and the chromatogram for Figure 3 .

[0063] Table 3

[0064] Peak Retention time area area% 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

[0065] As can be seen from the above, the nafamostat mesylate prepared by the two prior art methods respectively adopted in the present invention contains a large unknown impurity and cannot meet the high quality requirements.

[0066] This experimental example further studied the removal method of single impurities, as follows:

[0067] (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 4.

[0068] Table 4

[0069]

[0070]

[0071] By examining different solvents, different mixed solvents, different ratios of mixed solvents and refining times, the unknown impurities could not be removed to less than 0.1%. Furthermore, the present invention continues to try to reduce the content of larger unknown impurities by controlling the reaction conditions.

[0072] (2) The condensation method using a condensation agent was used to reduce the content of large unknown impurities by optimizing the reaction conditions. The specific research was conducted based on the method in Reference 1. The research results are shown in Table 5.

[0073] Table 5

[0074]

[0075]

[0076]

[0077] 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.

[0078] Example 1

[0079] Step 1: Preparation of 6-iminomethyl ester-2-naphthol hydrochloride

[0080] First, add 624.8g of anhydrous methanol into the reaction bottle, add 612.3g of acetyl chloride dropwise at 0-5°C with stirring, stir at 5°C for 1h after the addition is complete, then add 219.9g of 6-cyano-2-naphthol, react at 20°C for 15h, then add 3.3kg of methyl tert-butyl ether, stir at 5°C for crystallization for 1h, filter, rinse with 500ml of methyl tert-butyl ether, and dry under reduced pressure at 35°C for 5h to obtain 296.6g of 6-iminomethyl ester-2-naphthol hydrochloride, with a yield of 95.99%.

[0081] Step 2: Preparation of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride

[0082] Add 215.6 g of p-guanidinobenzoic acid hydrochloride, 237.7 g of 6-iminomethyl ester-2-naphthol hydrochloride prepared according to step 1, and 3.3 kg of DMF to a reaction bottle, stir to dissolve, control the temperature at 18-20° C., add 230.0 g of EDCI, control the temperature at 20° C. and react for 1 h to obtain a DMF solution of 6-iminomethyl ester-naphthalene-2-yl-4-guanidinebenzoate hydrochloride (yield 100%), which is directly used in the next step.

[0083] Step 3: Preparation of Nafamostat Carbonate

[0084] In the DMF solution of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride obtained in the previous step, 76.8 g of ammonium carbonate was added in batches at a temperature of 22-25 ° C. After the addition, the temperature was controlled at 25 ° C. to react for 4.5 h, 2.0 kg of purified water was added, the temperature was controlled at 5 ° C. and stirred for crystallization for 1.5 h, filtered, and washed with 500 ml of purified water to obtain nafamostat carbonate (with a yield of 100%), which was directly used in the next step.

[0085] Step 4: Preparation of Nafamostat Mesylate

[0086] The nafamostat carbonate obtained in the previous step was dispersed into 1.9 kg acetone, 201.8 g methanesulfonic acid was added at a temperature of 0 to 10 ° C, and then 1.9 kg purified water was added, the temperature was raised to 55 ° C for dissolution, and then 11.3 kg acetone was added, the temperature was controlled at 5 ° C for crystallization for 1.5 h, filtered, 1 L acetone was rinsed, and vacuum dried at 45 ° C for 4.5 h to obtain 412.1 g nafamostat mesylate. The present embodiment confirms that the synthesized nafamostat mesylate is obtained by nuclear magnetic resonance and mass spectrometry detection (see mass spectrum for details). Figure 4 , NMR spectrum see Figure 5 ). Yield: 76.37%, HPLC purity: 99.895%, maximum single impurity: 0.07% (the purity chromatographic detection method in each embodiment and comparative example is described in the above experimental example).

[0087] Example 2

[0088] Step 1: Preparation of 6-iminomethyl ester-2-naphthol hydrochloride

[0089] First, add 416.5g of anhydrous methanol into the reaction bottle, add 408.2g of acetyl chloride dropwise at a temperature of 0-10°C with stirring, stir at 10°C for 1h after the addition is complete, then add 219.9g of 6-cyano-2-naphthol, react at a temperature of 10°C for 12h, then add 2.2kg of methyl tert-butyl ether, stir and crystallize at a temperature of 10°C for 2h, filter, rinse with 500ml of methyl tert-butyl ether, and dry under reduced pressure at 30°C for 6h to obtain 293.5g of 6-iminomethyl ester-2-naphthol hydrochloride, with a yield of 94.99%.

[0090] Step 2: Preparation of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride

[0091] Add 215.6 g of p-guanidinobenzoic acid hydrochloride, 237.7 g of 6-iminomethyl ester-2-naphthol hydrochloride prepared according to step 1, and 3.2 kg of DMSO to a reaction bottle, stir to dissolve, control the temperature at 10-12 ° C, add 253.0 g of CDI, control the temperature at 10 ° C to react for 2 hours, and obtain a DMSO solution of 6-iminomethyl ester-naphthalene-2-yl-4-guanidinebenzoate hydrochloride (yield 100%), which is directly used in the next step.

[0092] Step 3: Preparation of Nafamostat Carbonate

[0093] In the DMSO solution of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride obtained in the previous step, 48.0 g of ammonium carbonate was added in batches at a temperature of 20-30 ° C. After the addition, the temperature was controlled at 20 ° C for 4 h, 1.6 kg of purified water was added, the temperature was controlled at 0 ° C for stirring and crystallization for 1 h, filtered, and washed with 500 ml of purified water to obtain nafamostat carbonate (with a yield of 100%), which was directly used in the next step.

[0094] Step 4: Preparation of Nafamostat Mesylate

[0095] The nafamostat carbonate obtained in the previous step was dispersed in 2.4 kg of acetone, and 192.2 g of methanesulfonic acid was added at a temperature of 0-10 ° C, and then 2.4 kg of purified water was added, and the temperature was raised to 50 ° C to dissolve, and then 8.5 kg of acetone was added, and the temperature was controlled at 10 ° C for crystallization for 2 hours, filtered, eluted with 1 L of acetone, and vacuum dried at 40 ° C for 5 hours to confirm that 404.7 g of nafamostat mesylate was obtained. The yield was 75.00%, HPLC purity: 99.785%, and the maximum single impurity: 0.07%.

[0096] Example 3

[0097] Step 1: Preparation of 6-iminomethyl ester-2-naphthol hydrochloride

[0098] First, add 999.6g of anhydrous methanol into the reaction bottle, add 1020.5g of acetyl chloride dropwise at 0-3°C with stirring, stir at 0°C for 1h after the addition is complete, then add 219.9g of 6-cyano-2-naphthol, react at 30°C for 15h, then add 4.4kg of methyl tert-butyl ether, stir and crystallize at 10°C for 1h, filter, rinse with 500ml of methyl tert-butyl ether, and dry under reduced pressure at 40°C for 4h to obtain 299.7g of 6-iminomethyl ester-2-naphthol hydrochloride, with a yield of 97%.

[0099] Step 2: Preparation of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride

[0100] Add 215.6 g of p-guanidinobenzoic acid hydrochloride, 237.7 g of 6-iminomethyl ester-2-naphthol hydrochloride prepared according to step 1, and 6.5 kg of DMF to a reaction bottle, stir to dissolve, add 309.5 g of DCC at a temperature of 28-30 ° C, and react at a temperature of 30 ° C for 1 h to obtain a DMF solution of 6-iminomethyl ester-naphthalene-2-yl-4-guanidinebenzoate hydrochloride (yield 100%), which is directly used in the next step.

[0101] Step 3: Preparation of Nafamostat Carbonate

[0102] In the DMF solution of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride obtained in the previous step, 96.0 g of ammonium carbonate was added in batches at a temperature of 25-30 ° C. After the addition, the temperature was controlled at 30 ° C. to react for 5 h, 6.5 kg of purified water was added, the temperature was controlled at 10 ° C. and stirred for crystallization for 2 h, filtered, and washed with 500 ml of purified water to obtain nafamostat carbonate (with a yield of 100%), which was directly used in the next step.

[0103] Step 4: Preparation of Nafamostat Mesylate

[0104] Disperse the nafamostat carbonate obtained in the previous step into 2.4 kg of acetone, add 211.2 g of methanesulfonic acid at a temperature of 0-10 ° C, then add 2.4 kg of purified water, heat to 60 ° C to dissolve, then add 14.1 kg of acetone, control the temperature at 10 ° 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 404.5 g of nafamostat mesylate is obtained. The yield is 74.96%, the HPLC purity is: 99.870%, and the maximum single impurity is: 0.07%.

[0105] Example 4

[0106] Step 1: Preparation of 6-iminoethyl ester-2-naphthol hydrochloride

[0107] First, add 1197.8g of anhydrous ethanol to the reaction bottle, add 612.3g of acetyl chloride dropwise at a temperature of 0-5°C with stirring, stir at 5°C for 1h after the addition is complete, then add 219.9g of 6-cyano-2-naphthol, react at a temperature of 25°C for 15h, then add 3.3kg of methyl tert-butyl ether, stir and crystallize at a temperature of 0°C for 1h, filter, rinse with 500ml of methyl tert-butyl ether, and dry under reduced pressure at 35°C for 5h to obtain 317.5g of 6-iminoethyl ester-2-naphthol hydrochloride, with a yield of 97.04%.

[0108] Step 2: Preparation of 6-iminoethyl-naphthalene-2-yl-4-guanidine benzoate hydrochloride

[0109] Add 215.6 g of p-guanidinobenzoic acid hydrochloride, 251.8 g of 6-iminoethyl ester-2-naphthol hydrochloride prepared according to step 1, and 4.3 kg of DMF to a reaction bottle, stir to dissolve, add 230.0 g of EDCI at a temperature of 20° C., and react at a temperature of 20° C. for 1 h to obtain a DMF solution of 6-iminoethyl ester-naphthalene-2-yl-4-guanidinobenzoate hydrochloride (yield 100%), which is directly used in the next step.

[0110] Step 3: Preparation of Nafamostat Carbonate

[0111] In the DMF solution of 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride obtained in the previous step, 76.8 g of ammonium carbonate was added in batches at a temperature of 20-30 ° C. After the addition, the temperature was controlled at 25 ° C. to react for 4.5 h, 2.6 kg of purified water was added, the temperature was controlled at 5 ° C. and stirred for crystallization for 1.5 h, filtered, and washed with 500 ml of purified water to obtain nafamostat carbonate (with a yield of 100%), which was directly used in the next step.

[0112] Step 4: Preparation of Nafamostat Mesylate

[0113] The nafamostat carbonate obtained in the previous step was dispersed in 1.9 kg acetone, 201.8 g methanesulfonic acid was added at a temperature of 0 to 10 ° C, and then 1.9 kg purified water was added, and the temperature was raised to 55 ° C for dissolution, and then 11.7 kg acetone was added, and the temperature was controlled to 0 ° C for crystallization for 1 h, filtered, 1 L acetone was rinsed, and vacuum dried at 45 ° C for 4.5 h to obtain 410.5 g nafamostat mesylate. It was confirmed that the synthesized product was nafamostat mesylate (see mass spectrum) by the method described in Example 1. Figure 6 , NMR spectrum see Figure 7 ). Yield: 76.08%, HPLC purity: 99.840%, maximum single impurity: 0.08%.

[0114] Comparative Example 1

[0115] This comparative example provides a method for preparing nafamostat mesylate, which is basically the same as the method in Example 1, except that pyridine is used instead of DMF as the reaction solvent in step 2 and step 3. Finally, the yield of nafamostat mesylate is 50.78%, HPLC purity is 99.247%, and the maximum single impurity is 0.45%.

[0116] Comparative Example 2

[0117] This comparative example provides a method for preparing nafamostat mesylate, which is basically the same as the method in Example 1, except that dimethylacetamide (DMA) is used instead of DMF as the reaction solvent in step 2 and step 3. Finally, the yield of nafamostat mesylate is 60.33%, HPLC purity is 99.348%, and the maximum single impurity is 0.25%.

[0118] Comparative Example 3

[0119] This comparative example provides a method for preparing nafamostat mesylate, comprising:

[0120] With p-guanidinobenzoic acid hydrochloride and 6-amidino-2-naphthol methanesulfonate as raw materials, EDCI as condensing agent, feed ratio of 1:1:1.2, DMF as reaction solvent, the amount is 15 times the mass of p-guanidinobenzoic acid hydrochloride, reaction temperature is 10-30°C, and reaction time is 1h. After the reaction is completed, saturated sodium bicarbonate aqueous solution is mixed with the reactants, the amount of saturated sodium bicarbonate aqueous solution is the same as the amount of DMF, and the prepared nafamostat carbonate is then prepared by the same method as step 4 of Example 1. By the method described in Example 1, it is confirmed that the synthesized nafamostat mesylate is 40.25%, HPLC purity: 98.312%, and maximum single impurity: 0.81%.

[0121] Comparative Example 4

[0122] This comparative example provides a method for preparing nafamostat mesylate, comprising:

[0123] With p-guanidinobenzoic acid hydrochloride and 6-amidino-2-naphthol methanesulfonate as raw materials, EDCI as a condensing agent, a feed ratio of 1:1:1.2, pyridine as a reaction solvent, an amount of 15 times the mass of p-guanidinobenzoic acid hydrochloride, a reaction temperature of 10-30°C, and a reaction time of 1h. After the reaction is completed, the reactant is mixed with a saturated sodium bicarbonate aqueous solution, the amount of the saturated sodium bicarbonate aqueous solution is the same as the amount of DMF, and the prepared nafamostat carbonate is then prepared by the same method as in step 4 of Example 1. By the method described in Example 1, it is confirmed that the synthesized nafamostat mesylate is 40.47%, HPLC purity: 98.064%, and the maximum single impurity: 1.52%.

[0124] 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, include: (1) preparing 6-iminoester-2-naphthol hydrochloride; (2) preparing 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride in a reaction solvent of DMF or DMSO; (3) preparing nafamostat carbonate in a reaction solvent, DMF or DMSO; (4) Preparation of nafamostat mesylate.

2. The method according to claim 1, characterized in that In step (1), the 6-iminoester-2-naphthol hydrochloride is 6-iminomethyl ester-2-naphthol hydrochloride or 6-iminoethyl ester-2-naphthol hydrochloride; when generating 6-iminomethyl ester-2-naphthol hydrochloride, 6-cyano-2-naphthol, anhydrous methanol and acetyl chloride are reacted; when generating 6-iminoethyl ester-2-naphthol hydrochloride, 6-cyano-2-naphthol, anhydrous ethanol and acetyl chloride are reacted; In step (2), the 6-iminoester-2-naphthol hydrochloride prepared in step (1) is reacted with p-guanidinobenzoic acid hydrochloride in DMF or DMSO in the presence of a condensing agent to prepare 6-iminoester-naphthalene-2-yl-4-guanidinobenzoate hydrochloride; In step (3), the 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride prepared in step (2) is reacted with ammonium carbonate in DMF or DMSO to prepare nafamostat carbonate; In step (4), the nafamostat carbonate prepared in step (3) is reacted with methanesulfonic acid in acetone to prepare nafamostat mesylate.

3. The method according to claim 2, characterized in that In step (1), when generating 6-iminomethyl ester-2-naphthol hydrochloride, the molar ratio of 6-cyano-2-naphthol: acetyl chloride: anhydrous methanol is 1: (4-10): (10-24), preferably 1: 6: 15; when generating 6-iminoethyl ester-2-naphthol hydrochloride, the molar ratio of 6-cyano-2-naphthol: acetyl chloride: anhydrous ethanol is 1: (4-10): (10-24), preferably 1: 6: 20; The reaction temperature in step (1) is 10-30°C.

4. The method according to claim 2 or 3, characterized in that: In step (2), the 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride is 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride or 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride; the condensing agent is CDI, DCC or EDCI; and the reaction temperature in step (2) is 10 to 30°C.

5. The method according to any one of claims 2 to 4, characterized in that: In step (3), when 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride is used as the raw material, the molar ratio of 6-iminomethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride to ammonium carbonate is 1:(0.5-1); When 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride is used as the raw material, the molar ratio of 6-iminoethyl ester-naphthalene-2-yl-4-guanidine benzoate hydrochloride to ammonium carbonate is 1:(0.5-1); The reaction temperature in step (3) is 20-30°C.

6. The method according to any one of claims 2 to 5, characterized in that: In step (4), the reaction of nafamostat carbonate and methanesulfonic acid is carried out at 0-10°C.

7. The method according to any one of claims 1 to 6, characterized in that: include: (1) Add acetyl chloride dropwise to anhydrous methanol or anhydrous ethanol under stirring and temperature control at 0 to 10°C, stir at 0 to 10°C for 1 to 2 hours after the addition is complete, then add 6-cyano-2-naphthol, react at 10 to 30°C for 12 to 15 hours, then add methyl tert-butyl ether, stir and crystallize at 0 to 10°C for 1 to 2 hours to obtain 6-iminoester-2-naphthol hydrochloride; (2) dissolving p-guanidinobenzoic acid hydrochloride and 6-iminoester-2-naphthol hydrochloride in DMF or DMSO with stirring, adding a condensing agent at a temperature of 10 to 30° C., and reacting at 10 to 30° C. for 1 to 2 hours to obtain a DMF or DMSO solution of 6-iminoester-naphthalene-2-yl-4-guanidinobenzoate hydrochloride; (3) In a DMF or DMSO solution of 6-iminoester-naphthalene-2-yl-4-guanidine benzoate hydrochloride, add ammonium carbonate in batches at a temperature of 20 to 30° C., react at 20 to 30° C. for 4 to 5 hours, add purified water, control the temperature at 0 to 10° C., stir and crystallize for 1 to 2 hours, and obtain nafamostat carbonate; (4) Dispersing 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 to 0 to 10° C. to crystallize for 1 to 2 hours, and obtaining nafamostat mesylate.

8. The method according to claim 7, characterized in that In step (1), during crystallization, the amount of methyl tert-butyl ether added is 10 to 20 times the mass of 6-cyano-2-naphthol; after crystallization, the method further comprises the steps of filtering, eluting with methyl tert-butyl ether, and drying; and the drying conditions are: drying under reduced pressure at 30 to 40° C. for 4 to 6 hours.

9. The method according to claim 7 or 8, characterized in that: In step (2), the molar ratio of p-guanidinobenzoic acid hydrochloride to 6-iminoester-2-naphthol hydrochloride is 1:(0.9-1.1); the mass ratio of p-guanidinobenzoic acid hydrochloride to DMF or DMSO is 1:(14.8-30); the molar ratio of p-guanidinobenzoic acid hydrochloride to the condensing agent is 1:(1.2-1.6); And / or, in step (3), during crystallization, the amount of purified water added is 0.5 to 1 times the mass of DMF or DMSO, and after crystallization, the steps of filtering and washing with purified water are also included.

10. The method according to any one of claims 7 to 9, characterized in that: In step (4), the mass ratio of nafamostat carbonate to acetone is 1:(3-5); The molar ratio of nafamostat carbonate to methanesulfonic acid is 1:(2.0-2.2); During crystallization, the amount of purified water added is 3-5 times the mass of nafamostat carbonate, and the amount of acetone added is 18-30 times the mass of nafamostat carbonate; After crystallization, the process also includes filtering, rinsing with acetone, and drying; the drying conditions are: vacuum drying at 40-50° C. for 4-5 hours.

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