Preparation Method and Application of a Nafamostat Intermediate

Abstract

The invention belongs to the field of pharmaceutical chemistry preparation, discloses a preparation method of 6-amidino-2-naphthols and its intermediate M1, and prepares nafamostat mesylate using the method. The preparation method provided by the present invention is: using SM1 as starting material, and obtaining intermediate M1 by hydroxylamine addition, M1 is reduced to obtain 6-amidino-2-naphthols M2 by means of continuous reaction or stepwise reaction, condensed under the action of a condensing agent, and then methanesulfonic acid salifies to obtain nafamostat mesylate. The preparation method of the present invention has short reaction time, high yield, high product purity, mild reaction conditions, simple post-processing, avoids the dangerous reaction, dangerous reagent, controlled reagent involved in traditional route, therefore the safety of operation and product is higher, is conducive to industrialized large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of pharmaceutical chemical preparation, and in particular to a preparation method and application of a nafamostat mesylate intermediate. Background Art

[0002] Nafamostat mesylate is a synthetic serine protease inhibitor that strongly inhibits the coagulation and fibrinolytic systems (thrombin, XIIa, Xa, VIIa, plasmin), the kallikrein-kinin system (kallikrein), the complement system (C1r, C1s), pancreatic enzymes (trypsin, kallikrein), and phospholipase A2. It can prolong coagulation time and inhibit platelet aggregation and complement hemolysis. Clinically, it can be used to improve acute symptoms of pancreatitis, disseminated intravascular coagulation, and prevent coagulation of perfused blood during extracorporeal circulation (hemodialysis and plasma exchange) in patients with bleeding lesions or bleeding tendencies.

[0003] Nafamostat mesylate was originally developed by Torii Pharmaceutical Co., Ltd. in Japan and launched in Japan in October 1986. There are two main synthetic routes for nafamostat: one is through the condensation of 4-guanidinobenzoic acid and 6-amidino-2-naphthol; the other is through the reaction of 4-guanidinobenzoyl chloride and 6-amidino-2-naphthol. 6-amidino-2-naphthol is a key intermediate and has relatively few synthetic methods. Route 1 (Aoyama, Okutome, Nakayama T, et al.; Chemical and Pharmaceutical Bulletin, 33, 1985; 1458-1471) involves passing saturated HCl gas into an alcoholic solution of 6-cyano-2-naphthol, allowing a Pinner reaction under acidic conditions to produce 6-hydroxy-2-naphthyliminomethyl ester, which is then aminolyzed by the addition of ammonia gas to yield 6-amidino-2-naphthol. This route uses highly corrosive hydrochloric acid gas, which is prone to causing the loss of reactors in actual industrial production, is highly dangerous, and has a long reaction time. Route two (CN103896809) improves route one by using acyl chloride to generate hydrochloric acid in situ to promote the Pinner reaction. Although this method avoids the use of hydrochloric acid gas, the corrosion of equipment under acidic conditions still exists. Route three (CN113999145) obtains 6-hydroxy-2-naphthyl imine methyl ester by alcoholysis of 6-cyano-2-naphthol under sodium ethoxide / ethanol conditions, and uses ammonium chloride as an ammonia source to make its aminolysis obtain 6-amidino-2-naphthol, but there is a situation where the reaction time is long. Summary of the Invention

[0004] To overcome the above technical deficiencies, the present invention aims to provide a method for preparing a nafamostat intermediate and a method for preparing nafamostat using the intermediate. The method solves the problems of the prior art such as long reaction time, low yield, low product purity, and involvement of hazardous reactions and hazardous reagents, thereby achieving simple operation, short production cycle, good equipment compatibility, high safety, and being more suitable for industrial large-scale production.

[0005] The first aspect of the present invention provides a method for preparing a nafamostat mesylate intermediate: SM1 reacts with a hydroxylamine aqueous solution or hydroxylamine hydrochloride in an organic solvent under the action of a base to obtain M1, and then M1 reacts with a hydrogen source in an organic solvent under the action of a reducing agent through a continuous or stepwise reaction to obtain M2.

[0006]

[0007] Furthermore, the reducing agent is selected from zinc powder, palladium carbon or Raney nickel.

[0008] Furthermore, the hydrogen source is selected from hydrogen, acetic acid, hydrochloric acid or ammonium chloride.

[0009] Furthermore, the organic solvent is selected from methanol, ethanol or isopropanol.

[0010] The second aspect of the present invention provides a process for preparing nafamostat mesylate via the M1 intermediate, the process comprising the steps of:

[0011]

[0012] (1) SM1 reacts with hydroxylamine aqueous solution or hydroxylamine hydrochloride in an organic solvent under the action of a base to obtain M1;

[0013] (2) M1 reacts with a hydrogen source in an organic solvent under the action of a reducing agent to obtain M2 through a continuous reaction or a stepwise reaction;

[0014] (3) M2 and SM2 undergo esterification reaction under the action of a condensing agent to obtain the intermediate M3;

[0015] (4) M3 is reacted with methanesulfonic acid in an aqueous solvent system to form a salt to obtain nafamostat mesylate.

[0016] Furthermore, the base in step 1 of the present invention is selected from a base that can free hydroxylamine hydrochloride; the base that can free hydroxylamine hydrochloride is selected from: triethylamine, diisopropylethylamine, trimethylamine, diethylamine, dimethylamine, sodium ethylenediamine carbonate, potassium carbonate, cesium carbonate, sodium hydroxide or hydroxide; in some embodiments of the present invention, the base is preferably triethylamine or diisopropylethylamine.

[0017] Furthermore, in steps 1 and 2 of the present invention, the organic solvent is selected from methanol, ethanol, and isopropanol. In a specific embodiment of the present invention, the reaction solvent is preferably ethanol.

[0018] Furthermore, the reducing agent in step 2 of the present invention is selected from zinc powder, palladium carbon or Raney nickel; in a specific embodiment of the present invention, the reducing agent is preferably zinc powder.

[0019] Furthermore, the hydrogen source in step 2 of the present invention is selected from hydrogen, acetic acid, hydrochloric acid, and ammonium chloride; in a specific embodiment of the present invention, the hydrogen source is preferably acetic acid.

[0020] Furthermore, the condensing agent in step 3 of the present invention is selected from DCC / DMAP, HATU, HBTU or EDCI. In a specific embodiment of the present invention, DCC / DMAP is preferred.

[0021] Furthermore, the aqueous solvent system in step 4 of the present invention is selected from acetone / water or ethanol / water; in a specific embodiment of the present invention, acetone / water is preferred.

[0022] Furthermore, the present invention provides a method for preparing nafamostat mesylate via the M1 intermediate, the method comprising the following steps:

[0023] (1) 5.0 g (29.55 mmol) of SM1, 6.16 g of hydroxylamine hydrochloride (88.65 mmol, 3.0 eq), and 50 mL of anhydrous ethanol (10 v) were added to a 100 mL reaction flask in sequence and stirred at room temperature. During the stirring process, 8.97 g of triethylamine (88.65 mmol, 3.0 eq) was added dropwise and heated to 75 ° C. The reaction was allowed to proceed for about 1 h. The reaction was complete as determined by TLC / LCMS. After removing the solvent in vacuo, 100 mL of water was added to the residual solid. 1 N hydrochloric acid was added dropwise with stirring to adjust the pH to 2-3. 50 mL of ethyl acetate was added for extraction. The aqueous phase was retained. After adjusting the pH to alkaline with saturated sodium bicarbonate aqueous solution, the precipitated solid was filtered off and the filter cake was dried under air at 60 ° C to obtain 5.4 g of yellow solid M1 with a yield of 90.3% and a purity of 97.17% by HPLC.

[0024] (2) In a 100 mL reaction flask, 5.0 g (24.72 mmol) of M1 and 50 mL of anhydrous ethanol (10 v) were added in sequence and stirred at room temperature. During the stirring process, 8.08 g of zinc powder (123.6 mmol, 5.0 eq) was added. The atmosphere was replaced with nitrogen twice. The temperature was raised to 60 ° C. 5 mL (1 v) of acetic acid was added dropwise at 60 ° C. The reaction was kept at 85 ° C for 1-2 h. The reaction was complete as determined by TLC / LCMS. The mixture was cooled to room temperature, 3.1 mL (1.5 eq) of concentrated hydrochloric acid was added dropwise, and the mixture was stirred at room temperature for 10 minutes. The mixture was filtered and the filtrate was retained. The filtrate was dried to obtain 5.06 g of brown-yellow solid M2 with a yield of 92% and a purity of 97.93% by HPLC.

[0025] (3) 2.0 g M2 (8.98 mmol), 2.32 g SM2 (10.78 mmol, 1.2 eq), and 40 mL pyridine (20 v) were added to a 100 mL reaction flask in sequence. After cooling to 0°C in an ice bath, 2.22 g DCC (10.78 mmol, 1.2 eq) and 219 mg DMAP (1.80 mmol, 0.2 eq) were added in sequence. The mixture was reacted in an ice bath for 1 h, and then naturally warmed to room temperature for 12-15 h. The reaction was complete when detected by LCMS. The solid was filtered out by suction, and the filter cake was washed twice with 20 mL pyridine. The filter cake was added to 40 mL water and stirred for 10 minutes. The solid was filtered out by suction, and the filtrate was retained. Saturated sodium bicarbonate solution was then added dropwise to the filtrate, the solid was filtered out, and the solution was dried to obtain 3.55 g of nafamostat carbonate as a yellow solid with a yield of 83.8% and a purity of 92.6% by HPLC.

[0026] (4) 3.0 g of nafamostat carbonate (6.36 mmol) was suspended in 15 mL of water (5 v), cooled to 0°C, 1.35 g of methanesulfonic acid (13.99 mmol, 2.2 eq) was dissolved in 30 mL (10 v) of acetone, and added dropwise into the system, controlling the temperature below 5°C. After the addition was complete, the system was heated to room temperature, and 150 mL (50 v) of acetone was added dropwise. The system was crystallized for 4 h, filtered, and dried to obtain 3.2 g of nafamostat mesylate with a yield of 93.2% and an HPLC purity of 99.4%.

[0027] The beneficial effects brought about by the invention are:

[0028] 1. The present invention provides a novel method for preparing nafamostat, a key intermediate 6-amidino-2-naphthol, from an intermediate M1, and utilizes this route to prepare nafamostat mesylate. The method has short reaction time, high yield, high product purity, is easy to scale up, and is suitable for industrial large-scale production.

[0029] 2. The entire route of the present invention does not involve the hazardous reactions, hazardous reagents, and controlled reagents mentioned in the prior art, thereby improving the safety of reactions, operations, and products, while reducing the generation of three wastes and lowering production costs. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the examples, but is not intended to limit the present invention. Any equivalent replacements in the art made according to the disclosure of the present invention fall within the scope of protection of the present invention. Specific experimental methods not mentioned in the following examples are generally carried out according to conventional experimental methods. Reagents in the present invention are all commercially available products.

[0031] The structures of the compounds were determined by nuclear magnetic resonance ( 1 HNMR) to determine.

[0032] Nuclear magnetic resonance (NMR) 1 HNMR) shifts (δ) are given in parts per million (ppm); nuclear magnetic resonance ( 1 HNMR) was determined using 1 HNMR was performed on a Bruker AVANCE-400 instrument. The solvent used was DMSO-d6, the internal standard was tetramethylsilane (TMS), and the chemical shift was based on 10 -6 The units are given in ppm.

[0033] The HPLC spectra were determined using an Agilent 1260DAD (or Shimadzu LC-2030) liquid chromatograph. In this application, HPLC purity was determined using the following method:

[0034] (1) Chromatographic columns using octadecylsilane bonded silica gel as filler;

[0035] (2) Detector: UV detector (wavelength 254 nm);

[0036] (3) Flow rate: 1.0 mL per minute;

[0037] (4) Run time: gradient elution;

[0038] (5) Test solution: Prepare freshly before use. Take an appropriate amount of the product, accurately weigh it, dissolve it in methanol, and quantitatively dilute it to a solution containing approximately 1 mg per 1 mL.

[0039] (6) Injection volume: 10 μl. The sample solution was determined by automatic integration and the purity of the sample was calculated based on the peak area.

[0040] Definition and Explanation:

[0041]

[0042] The present invention will be further described below with reference to specific embodiments:

[0043] Example 1 Preparation of Intermediate M1

[0044] To a 100 mL reaction flask were added 5.0 g (29.55 mmol) of SM1, 6.16 g of hydroxylamine hydrochloride (88.65 mmol, 3.0 eq), and 50 mL of anhydrous ethanol (10 v) in sequence. The mixture was stirred at room temperature. During stirring, 8.97 g of triethylamine (88.65 mmol, 3.0 eq) was added dropwise. The mixture was heated to 75° C. and reacted for about 1 h. The reaction was complete as determined by TLC / LCMS. After removing the solvent in vacuo, 100 mL of water was added to the residual solid. 1N hydrochloric acid was added dropwise with stirring to adjust the pH to 2-3. Extraction was performed with 50 mL of ethyl acetate. The aqueous phase was retained and the pH was adjusted to alkaline with saturated sodium bicarbonate aqueous solution. The precipitated solid was filtered off and the filter cake was air-dried at 60° C. to obtain 5.4 g of M1 as a yellow solid (HPLC: 97.17%) in a yield of 90.3%.

[0045] 1 H NMR (400MHz, DMSO-d6) δ9.92(s,1H),9.69(s,1H),8.09(d,J=1.7Hz,1H),7.82–7.70(m,2H),7.64(d,J=8.7Hz,1H),7.17–7.08(m,2H),5.91(s,2H).

[0046] 13 C NMR (101MHz, DMSO-d6) δ155.90,151.07,134.82,129.80,127.39,127.04,125.69,124.34,123.57,118.95,108.67.

[0047] Example 2 Preparation of Intermediate M2

[0048] To a 100 mL reaction flask, 5.0 g (24.72 mmol) of M1 and 50 mL of anhydrous ethanol (10 v) were added sequentially and stirred at room temperature. During the stirring process, 8.08 g of zinc powder (123.6 mmol, 5.0 eq) was added. The atmosphere was replaced with nitrogen twice, and the temperature was raised to 60° C. 5 mL (1 v) of acetic acid was added dropwise at 60° C. The reaction was kept at 85° C. for 1-2 h. The reaction was complete as determined by TLC / LCMS. The mixture was cooled to room temperature, 3.1 mL (1.5 eq) of concentrated hydrochloric acid was added dropwise, and the mixture was stirred at room temperature for 10 minutes. The mixture was filtered with suction, and the filtrate was retained. The filtrate was spin-dried to obtain 5.06 g of a brown-yellow solid M2 (HPLC: 97.93%), with a yield of 92%.

[0049] 1H NMR (400MHz, DMSO-d6) δ9.20 (s, 4H), 8.39 (d, J = 2.0Hz, 1H), 7.95 (d, J = 9.6Hz, 1H), 7.89 (d, J = 8.7Hz, 1H), 7.73 (dd, J = 8.7, 2.0Hz, 1H), 7.28–7.21 (m, 2H).

[0050] 13 C NMR (101MHz, DMSO-d6) δ165.56,158.15,137.19,131.08,129.45,126.75,126.18,123.77,121.72,120.29,108.77.

[0051] Example 3 Preparation of Intermediate M3

[0052] 2.0 g M2 (8.98 mmol), 2.32 g SM2 (10.78 mmol, 1.2 eq), and 40 mL pyridine (20 v) were added sequentially to a 100 mL reaction flask. After cooling to 0° C. in an ice bath, 2.22 g DCC (10.78 mmol, 1.2 eq) and 219 mg DMAP (1.80 mmol, 0.2 eq) were added sequentially. The mixture was reacted in an ice bath for 1 h, and then naturally warmed to room temperature for 12-15 h. The reaction was complete when detected by LCMS. The solid was filtered off with suction, and the filter cake was washed twice with 20 mL pyridine. The filter cake was added to 40 mL of water and stirred for 10 minutes. The solid was filtered off with suction, and the filtrate was retained. Saturated sodium bicarbonate solution was then added dropwise to the filtrate, the solid was filtered off, and the solution was dried to give 3.55 g of nafamostat carbonate as a yellow solid (HPLC: 92.6%), with a yield of 83.8%.

[0053] Example 4 Preparation of Nafamostat Mesylate

[0054] 3.0 g of nafamostat carbonate (6.36 mmol) was suspended in 15 mL of water (5 v), cooled to 0°C, 1.35 g of methanesulfonic acid (13.99 mmol, 2.2 eq) was dissolved in 30 mL (10 v) of acetone, and added dropwise into the system while controlling the temperature below 5°C. After the addition was complete, the system was heated to room temperature and 150 mL (50 v) of acetone was added dropwise. The system was crystallized for 4 h, filtered, and dried to obtain 3.2 g of nafamostat mesylate (HPLC: 99.4%) with a yield of 93.2%.

[0055] 1H NMR (400MHz, DMSO-d6) δ10.34(s,1H),9.51(s,2H),9.29(s,2H),8.62(d,J=1.9Hz,1H),8.29–8.17(m,4H ),8.04(d,J=2.3Hz,1H),7.98–7.88(m,5H),7.67(dd,J=8.9,2.3Hz,1H),7.52–7.45(m,2H),2.09(s,6H).

[0056] 13 C NMR(101MHz,DMSO-d6)δ165.60,163.98,155.36,150.42,141.61,135.62,131.57,130 .95,129.78,129.44,128.46,125.46,124.89,124.48,123.33,122.54,118.93,30.66.

[0057] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing a nafamostat mesylate intermediate, characterized in that: M1 reacts with acetic acid in ethanol under the action of reducing agent zinc powder to obtain M2. 。 2. A method for preparing nafamostat mesylate, characterized in that: The following steps are involved: ； (1) SM1 reacts with hydroxylamine aqueous solution or hydroxylamine hydrochloride in ethanol under the action of base to obtain M1; (2) M1 reacts with acetic acid in ethanol under the action of zinc powder as a reducing agent through continuous reaction or step-by-step reaction to obtain M2; (3) M2 reacts with SM2 in the presence of a condensing agent to obtain the intermediate M3; (4) M3 reacts with methanesulfonic acid in an aqueous solvent system to form a salt to obtain nafamostat mesylate.

3. The preparation method according to claim 2, wherein The base in step 1 is a base that can free hydroxylamine hydrochloride; the base that can free hydroxylamine hydrochloride is selected from: triethylamine, diisopropylethylamine, trimethylamine, diethylamine, dimethylamine, sodium ethylenediamine carbonate, potassium carbonate, cesium carbonate, sodium hydroxide or potassium hydroxide.

4. The preparation method according to claim 2, wherein The condensing agent in step 3 is selected from DCC / DMAP, HATU, HBTU or EDCI.

5. The preparation method according to claim 2, wherein The aqueous solvent system in step 4 is selected from an aqueous system of ketones or alcohols.

6. The preparation method according to claim 5, wherein The aqueous solvent system in step 4 is acetone / water or ethanol / water.

7. The preparation method according to claim 2, wherein The following steps are involved: (1) 5.0 g SM1, 6.16 g hydroxylamine hydrochloride, and 50 mL anhydrous ethanol were added to a 100 mL reaction flask in sequence. The mixture was stirred at room temperature and 8.97 g triethylamine was added dropwise. The mixture was heated to 75 °C until the reaction was complete. After removing the solvent in vacuo, 100 mL of water was added to the residual solid. Hydrochloric acid was added dropwise with stirring to adjust the pH to 2-3. 50 mL of ethyl acetate was added for extraction. The aqueous phase was retained and the pH was adjusted to alkaline with saturated sodium bicarbonate aqueous solution. The precipitated solid was filtered and dried by air to obtain 5.4 g of yellow solid M1 with a yield of 90.3% and a purity of 97.17% by HPLC. (2) Add 5.0 g of M1 and 50 mL of anhydrous ethanol to a 100 mL reaction flask in sequence, stir at room temperature and add 8.08 g of zinc powder, replace the atmosphere with nitrogen twice, heat to 60 °C, add 5 mL of acetic acid dropwise, and keep at 85 °C until the reaction is complete; cool to room temperature, add 3.1 mL of concentrated hydrochloric acid dropwise, stir at room temperature for 10 minutes, filter, retain the filtrate, and spin dry to obtain 5.06 g of brown-yellow solid M2, with a yield of 92% and a HPLC purity of 97.93%; (3) 2.0 g M2, 2.32 g SM2 and 40 mL pyridine were added to a 100 mL reaction bottle in sequence. After cooling to 0 °C in an ice bath, 2.22 g DCC and 219 mg DMAP were added in sequence. The reaction was continued in an ice bath for 1 h, and then at room temperature until the reaction was complete. The solid was filtered out, and the filter cake was washed with 20 mL pyridine. Saturated sodium bicarbonate solution was added dropwise to the filtrate, and the solid was filtered out and dried to obtain 3.55 g of yellow solid nafamostat carbonate with a yield of 83.8% and an HPLC purity of 92.6%. (4) Suspend 3.0 g of nafamostat carbonate in 15 mL of water, cool to 0 °C, dissolve 1.35 g of methanesulfonic acid in 30 mL of acetone, and add dropwise into the system, controlling the temperature below 5 °C. After the addition is complete, warm to room temperature and continue to add 150 mL of acetone. Crystallize for 4 h, filter, and dry to obtain 3.2 g of nafamostat mesylate, with a yield of 93.2% and a HPLC purity of 99.4%.

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