Preparation method of 1-N-ethyl micronomicin

Abstract

The invention discloses a preparation method of 1-N ethyl micronomicin, which comprises the following steps: dissolving 3, 2 '', 6 ''-N, N, N-triacetyl micronomicin in dichloromethane, cooling to-20 DEG C to-5 DEG C, slowly dropwise adding an acetaldehyde solution into a reaction flask at the temperature, and reacting at-20 DEG C to-5 DEG C after dropwise adding to obtain an imine compound; and adding potassium borohydride for reduction, removing acetyl, and purifying to obtain the 1-N ethyl micronomicin. According to the method, the triacetyl micronomicin is used as a starting material, an acetylation step for protecting hydroxyl is omitted, and the 1-bit N-ethylation reaction is directly performed on the triacetyl micronomicin. By controlling the temperature, the concentration and the dripping speed when acetaldehyde is dripped, the 1-N position ethylation directional reaction is realized, the loss caused by the 1-position amino reaction in the hydroxyl acetylation step is avoided, the reaction steps are saved, and meanwhile, the yield is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pharmaceutical chemistry, and in particular to a method for preparing 1-N-ethylkanamycin C1a sulfate impurity 1-N-ethylsinnomycin. BACKGROUND

[0002] 1-N-ethylkanamycin C1a sulfate is suitable for various infections caused by Escherichia coli, Klebsiella pneumoniae, Serratia, Oxydactylon, Enterobacter, Acinetobacter, Proteus, Haemophilus influenzae, Pseudomonas aeruginosa and Staphylococcus, etc. Clinical studies show that the product has good efficacy on the following infections: respiratory tract infections (such as acute bronchitis, acute exacerbation of chronic bronchitis, community-acquired pneumonia, etc.), kidney and urogenital system infections (such as acute pyelonephritis, cystitis, acute exacerbation of chronic pyelonephritis or chronic cystitis, etc.), skin and soft tissue and other infections (such as skin and soft tissue infections, post-traumatic, post-traumatic and postoperative infections, and other sensitive bacterial infections).

[0003] 1-N-ethylsinnomycin is one of the main impurities in 1-N-ethylkanamycin C1a sulfate raw material drugs and finished product preparations, and the structure of the impurity is as follows: .

[0004] In the detection of 1-N-ethylkanamycin C1a sulfate, the reference substance of the impurity is necessary, but there is no standard product available on the market at present, so the present application aims to explore the optimal and convenient method for preparing the reference substance.

[0005] Regarding the synthesis method of 1-N-ethylsinnomycin, Chinese patent document CN110066304A (application number 201910442380.7) discloses a synthesis method of 1-N-ethylsinnomycin, which takes triacetyl sinnomycin (3,2",6"-N,N,N-triacetylkanamycin C2b in the text) as the starting material, first acetylates the hydroxyl group, then performs N-ethylation reaction with acetaldehyde and potassium borohydride, and finally removes the protecting group with sodium hydroxide solution to obtain the product.

[0006] In the above method, the exposed 1-amino group is more active when the hydroxyl group is acetylated, and will be acetylated at the same time, resulting in more by-products, thereby affecting the purity and yield of the final product 1-N-ethylsinnomycin.

[0007] In addition to the above patent document, the prior art also uses the route of first protecting the hydroxyl group, then performing N-ethylation reaction, and finally removing the protecting group when preparing N-ethylkanamycin C1a. For example, CN101928312B and CN110372760A. Summary of the Invention

[0008] The technical problem to be solved by this invention is a method for preparing 1-N-ethylnomycin with high reaction selectivity, high yield and short route.

[0009] The technical solution for achieving the objective of this invention is a method for preparing 1-N-ethylnomycin, comprising the following steps: ① Dissolve 3,2'',6''-N,N,N-triacetylpyridinium in dichloromethane in a reaction flask, cool to -20℃~-5℃, and slowly add acetaldehyde solution dropwise to the reaction flask at this temperature. After the addition is complete, react at -20℃~-5℃ to obtain the imine compound shown in formula (II); .

[0010] ② Add potassium borohydride to the reaction solution obtained in step ①, stir for 0.5 to 1 hour, add boric acid to slow down, and continue stirring for 0.5 to 1 hour; .

[0011] ③ For the reaction solution obtained in step ②, concentrate the reaction solution to dryness under reduced pressure, add sodium hydroxide solution, heat under reflux for 18h to 48h, cool to below 35℃, and adjust the pH to 10 to 11 with sulfuric acid solution; .

[0012] ④ For the reaction solution obtained in step ③, dilute with reverse osmosis water, then pass it into a chromatography column. First, rinse with purified water, then elute with sulfuric acid. Collect the portion with a content of ≥90%, combine and concentrate to obtain the product.

[0013] Furthermore, in step ① above, the mass ratio of 3,2'',6''-N,N,N-triacetylpyridinium to acetaldehyde is 1:0.15 to 0.3.

[0014] Furthermore, in step ① above, 10% to 30% acetaldehyde aqueous solution is added dropwise to the reaction flask over 2 to 4 hours. After the addition is complete, the reaction is carried out at -20°C to -5°C for 1 to 4 hours.

[0015] Furthermore, in step ② above, the mass ratio of potassium borohydride to 3,2'',6''-N,N,N-triacetylpyridinium bromide is 0.14 to 0.2:1.

[0016] Optionally, in step ③ above, the concentration of the added sodium hydroxide solution is 20% to 30%.

[0017] Alternatively, in step ③ above, the pH value can be adjusted using a 2M to 8M sulfuric acid solution.

[0018] Furthermore, in step ④, the reaction solution obtained in step ② is diluted with reverse osmosis water to adjust the optical rotation value of the solution to 5-10.

[0019] Optionally, in step ④, the packing material in the chromatography column is a macroporous adsorption resin.

[0020] Alternatively, in step ④, the sample is rinsed with purified water for 8–15 hours.

[0021] Optionally, in step ④, the sulfuric acid is an aqueous solution of sulfuric acid with a pH value of 1.6 to 3.0.

[0022] This invention offers several advantages: Using triacetylpyrazine as the starting material, it omits the acetylation step for protecting the hydroxyl group and directly performs N-ethylation at the 1-position of triacetylpyrazine. By controlling the temperature, concentration, and dropping rate of acetaldehyde during addition, as well as the reaction temperature, the 1-N-ethylation reaction is directed, avoiding the loss caused by the 1-amino group reaction in the hydroxyl acetylation step. This not only saves reaction steps but also improves the yield. According to the preparation method of this invention, the purity of 1-N-ethylpyrazine can reach 99%, with a yield of 90%, making it a preparation method with a short route and high yield. Attached Figure Description

[0023] Figure 1 The HPLC chromatogram of 1-N-ethylnomycin prepared in Example 1 is shown.

[0024] Figure 2 The mass spectrum of 1-N-ethylnomycin prepared in Example 1.

[0025] Figure 3 The nuclear magnetic resonance H-ray spectrum of 1-N-ethylnomycin prepared in Example 1.

[0026] Figure 4 The nuclear magnetic resonance C-ray spectrum of 1-N-ethylnomycin prepared in Example 1. Detailed Implementation

[0027] The following describes some of the possible embodiments of the present invention, intended to provide a basic understanding of the invention, and is not intended to identify the key or decisive elements of the invention or limit the scope of protection. It is readily understood that, based on the technical solutions of the present invention, those skilled in the art can propose other interchangeable implementations without altering the essential spirit of the invention. Therefore, the following specific embodiments are merely illustrative examples of the technical solutions of the present invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solutions of the present invention.

[0028] (Example 1) The preparation method of 1-N-ethylnomycin in this embodiment includes the following steps: ①The compound of formula (II) is prepared by reacting 3,2'',6''-N,N,N-triacetylpyridinium (Ⅰ) with acetaldehyde, and the reaction formula is as follows: .

[0029] In a reaction flask, 100 g of 3,2'',6''-N,N,N-triacetylpyridinium trimethylolpropionate was dissolved in 300 mL of dichloromethane and cooled to -10 °C. At this temperature, 100 mL of 20% acetaldehyde aqueous solution was slowly added dropwise to the reaction flask over 3 hours. After the addition was complete, the reaction was continued at -10 °C for another 3 hours to obtain the imine compound shown in formula (II).

[0030] ② Prepare compound (III) from compound (II).

[0031] At -10℃, add 16g of potassium borohydride to the reaction solution obtained in step ① and stir for 0.5 to 1 hour (1 hour in this example); then add 200mL of borate buffer and continue stirring for 0.5 to 1 hour (1 hour in this example).

[0032] ③ Prepare compound (IV) from compound (III).

[0033] The reaction solution obtained in step ② was concentrated to dryness under reduced pressure, 500 mL of 20% sodium hydroxide solution was added, and the mixture was heated under reflux for 24 h. After cooling to below 35 °C, the pH was adjusted to 10-11 with 2 M-8 M (2 M in this example) sulfuric acid solution.

[0034] ④ Separation and purification. The reaction solution obtained in step ③ is diluted with reverse osmosis water to adjust the optical rotation value to 5-10 (8 in this example). Then, it is passed into a chromatography column (the packing material is macroporous adsorption resin). First, it is washed with pure water for 8-15 hours (10 hours in this example), and then eluted with sulfuric acid aqueous solution with a pH of 1.8-2.6 (2.2 in this example). The fraction with a purity ≥90% is collected and concentrated to obtain the product with a purity of 99.2% and a yield of 92%.

[0035] The HPLC chromatogram of 1-N-ethylnomycin obtained in this embodiment is shown in [reference needed]. Figure 1 Mass spectrum (see) Figure 2 The nuclear magnetic resonance H-ray spectrum is shown below. Figure 3 The nuclear magnetic resonance C-ray spectrum is shown below. Figure 4 .

[0036] (Example 2) The preparation method of 1-N-ethylpyridinium bromide in this embodiment is the same as that in Example 1, except that: In step ①, 100g of triacetylpyridinium chloride was dissolved in 300mL of dichloromethane in a reaction flask, the temperature was lowered to -5℃, and 200mL of 10% acetaldehyde solution was slowly added dropwise to the reaction flask. The addition was completed in 4 hours, and the reaction continued for 3 hours after the addition was completed.

[0037] In step ④, dilute sulfuric acid with a pH of 2.3 is used for elution.

[0038] The final product in this embodiment has a purity of 99.0% and a yield of 91%.

[0039] (Example 3) The preparation method of 1-N-ethylpyridinium bromide in this embodiment is the same as that in Example 1, except that: In step ①, 100g of triacetylpyridinium chloride was dissolved in 300mL of dichloromethane in a reaction flask, the temperature was lowered to -20℃, and 70mL of 30% acetaldehyde solution was slowly added dropwise to the reaction flask over 2 hours. After the addition was complete, the reaction continued for another 2 hours.

[0040] In step ④, dilute sulfuric acid with a pH of 2.4 is used for elution.

[0041] The final product in this embodiment has a purity of 99.0% and a yield of 90%.

[0042] (Example 4) The preparation method of 1-N-ethylpyridinium bromide in this embodiment is the same as that in Example 1, except that: In step ②, add 20g of potassium borohydride to the reaction solution obtained in step ① and stir for 0.5h. Then add 300mL of borate buffer and continue stirring for 0.5h.

[0043] In step ③, the reaction solution is concentrated to dryness under reduced pressure, 500 mL of 20% sodium hydroxide solution is added, and the mixture is heated under reflux for 18 h. After cooling to 20 °C, the pH is adjusted to 10-11 with 2M sulfuric acid solution.

[0044] (Example 5) In step ②, add 15g of potassium borohydride to the reaction solution obtained in step ① and stir for 45min. Then add 250mL of borate buffer and continue stirring for 45min.

[0045] In step ③, the reaction solution is concentrated to dryness under reduced pressure, 400 mL of 20% sodium hydroxide solution is added, and the mixture is heated under reflux for 36 h. After cooling to 15 °C, the pH is adjusted to 10-11 with 8 M sulfuric acid solution.

[0046] (Example 6) In step ②, add 18g of potassium borohydride to the reaction solution obtained in step ① and stir for 45 minutes. Add borate buffer and continue stirring for 1 hour.

[0047] In step ③, the reaction solution is concentrated to dryness under reduced pressure, 600 mL of 20% sodium hydroxide solution is added, and the mixture is heated under reflux for 48 h. After cooling to 15 °C, the pH is adjusted to 10-11 with 6 M sulfuric acid solution.

Claims

1. A method for preparing 1-N-ethylpyridamycin, characterized in that... Includes the following steps: ① Dissolve 3,2'',6''-N,N,N-triacetylpyridinium in dichloromethane in a reaction flask, cool to -20℃~-5℃, and slowly add acetaldehyde solution dropwise to the reaction flask at this temperature. After the addition is complete, react at -20℃~-5℃ to obtain the imine compound shown in formula (II). ； ② Add potassium borohydride to the reaction solution obtained in step ①, stir for 0.5–1 hour, add boric acid as a buffer, and continue stirring for another 0.5–1 hour. ； ③ For the reaction solution obtained in step ②, concentrate the reaction solution to dryness under reduced pressure, add sodium hydroxide solution, heat under reflux for 18h to 48h, and after cooling to below 35℃, adjust the pH to 10 to 11 with sulfuric acid solution. ； ④ For the reaction solution obtained in step ③, dilute with reverse osmosis water, then pass it into a chromatography column. First, rinse with purified water, then elute with sulfuric acid. Collect the portion with a content of ≥90%, combine and concentrate to obtain the product.

2. The method for preparing 1-N-ethylnomycin according to claim 1, characterized in that: In step ①, the mass ratio of 3,2'',6''-N,N,N-triacetylpyridinium to acetaldehyde is 1:0.15 to 0.

3.

3. The method for preparing 1-N-ethylnomycin according to claim 2, characterized in that: In step ①, add 10% to 30% acetaldehyde aqueous solution dropwise to the reaction flask over 2 to 4 hours. After the addition is complete, react at -20℃ to -5℃ for 1 to 4 hours.

4. The method for preparing 1-N-ethylnomycin according to claim 1, characterized in that: In step ②, the mass ratio of potassium borohydride to 3,2'',6''-N,N,N-triacetylpyridinium bromide is 0.14 to 0.2:

1.

5. The method for preparing 1-N-ethylnomycin according to claim 1, characterized in that: In step ③, the concentration of the added sodium hydroxide solution is 20% to 30%.

6. The method for preparing 1-N-ethylnomycin according to claim 5, characterized in that: In step ③, the pH value is adjusted using a 2M to 8M sulfuric acid solution.

7. The method for preparing 1-N-ethylpyridinium chloride according to claim 1, characterized in that: In step ④, the reaction solution obtained in step ② is diluted with reverse osmosis water to adjust the optical rotation value of the solution to 5-10.

8. The method for preparing 1-N-ethylnomycin according to claim 1, characterized in that: In step ④, the packing material in the chromatography column is a macroporous adsorption resin.

9. The method for preparing 1-N-ethylnomycin according to claim 1, characterized in that: In step ④, rinse with purified water for 8–15 hours.

10. The method for preparing 1-N-ethylpyridinium chloride according to claim 1, characterized in that: In step ④, the sulfuric acid is an aqueous solution of sulfuric acid with a pH value of 1.6 to 3.0.

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