CN114702510A

CN114702510A - Preparation method of rifabutin oxidized impurities

Info

Publication number: CN114702510A
Application number: CN202210494167.2A
Authority: CN
Inventors: 谭涛; 莫彬; 邓博; 王涵思; 唐朝军
Original assignee: Chongqing Huabangshengkai Pharm Co ltd
Current assignee: Chongqing Huabangshengkai Pharm Co ltd
Priority date: 2022-05-05
Filing date: 2022-05-05
Publication date: 2022-07-05
Anticipated expiration: 2042-05-05
Also published as: CN114702510B

Abstract

The invention belongs to the field of drug synthesis, and particularly relates to a preparation method of rifabutin oxidized impurities. The oxidized impurities are impurities generated in the preparation or storage process of rifabutin. The preparation method provided by the invention is relatively simple to operate, has high purity and is convenient to store, and the prepared impurities can be used as a reference substance for detecting related substances of rifabutin and are used for quality control of rifabutin bulk drugs and preparations thereof.

Description

Preparation method of rifabutin oxidized impurities

Technical Field

The invention belongs to the field of drug synthesis, and particularly relates to a preparation method of rifabutin oxidized impurities.

Background

The chemical name of Rifabutin is 4-N-isobutyl spiropiperidine rifamycin S (English name: Rifabutin), as shown in formula I, the Rifabutin is a rifamycin derivative containing spiropiperazinyl, and has broad-spectrum antibacterial activity. The action mechanism of the compound is the same as that of rifampicin, and the compound can form stable combination with the beta subunit of DNA-dependent RNA polymerase of microorganisms to inhibit the activity of the enzyme, thereby inhibiting the synthesis of bacterial RNA. Has been approved abroad for the prevention and treatment of widespread infection of Mycobacterium avium-M.intracellulare complex (MAC) in HIV-infected individuals, and also for the treatment of multi-drug resistant tuberculosis.

The Rifabutin oxidation impurity is shown as a formula II, is an important impurity in the Rifabutin, is an impurity C (Rifabutin N-oxide in English abbreviation, the relative retention time RRT is approximately equal to 1.20, and the standard is 0.5 percent) in USP standard, and is introduced into the Rifabutin through a synthesis process or a degradation mode. The content of the impurities in rifabutin bulk drugs and preparations has important influence on safety and effectiveness, and the control of the content of the impurities by comparing the impurities with a reference substance is the most effective way in the prior art.

At present, no relevant literature reports a synthesis method of rifabutin oxidation impurities, so that the synthesis method of the impurities is developed by utilizing a chemical synthesis technology, and the quality control of rifabutin bulk drugs and preparations is necessary.

Disclosure of Invention

One of the objectives of the present invention is to provide a method for preparing rifabutin oxidized impurities, which is relatively simple in operation, high in purity, and convenient for storage.

In order to achieve the purpose, the invention adopts the following technical scheme:

the impurities are generated in the preparation or storage process of rifabutin, and the structural formula of the impurities is shown as a formula II;

the preparation method specifically comprises the following steps:

1) dissolving the crude product of rifabutin by using absolute ethyl alcohol to obtain a solution A;

2) adding an oxidant into the solution A for reaction;

3) adding purified water into the product obtained in the step 2), and crystallizing and filtering to obtain a solid B;

4) pulping the solid B or purifying by column chromatography, dissolving with ethyl acetate, adding nonpolar solvent dropwise for crystallization, and drying.

Further, the weight ratio of the rifabutin crude product to the absolute ethyl alcohol in the step 1) is 1:3-1: 6.

Further, the oxidant in the step 2) is one of hydrogen peroxide or sodium periodate.

Further, the mass concentration of the hydrogen peroxide is 30% or 50%.

Further, the specific reaction conditions in the step 2) are as follows: 20-60 ℃ for 2-20 h.

Further, the weight ratio of the ethyl acetate used for pulping in the step 4) to the solid B is 2:1-8: 1.

Further, the eluents used for the column chromatography in the step 4) are methanol and dichloromethane.

Further, the volume ratio of the methanol to the dichloromethane is 1:10-1: 50.

Further, the weight ratio of the ethyl acetate used for dissolving in the step 4) to the crude rifabutin product is 1:1-5: 1.

Further, the nonpolar solvent in the step 4) is one or more of n-hexane, n-heptane or petroleum ether.

The invention has the beneficial effects that:

1) the invention provides a preparation method of rifabutin oxidized impurities, which is relatively simple to operate and mild and controllable in conditions.

2) The oxidized impurities prepared by the method provided by the invention have high purity, can be used as a reference substance for detecting related substances of rifabutin, and can be used for quality control of rifabutin bulk drugs and preparations thereof.

Drawings

FIG. 1 is a MS detection spectrum of a sample of example 1.

FIG. 2 is a MS detection spectrum of the sample of example 1.

Detailed Description

The following detailed description of the preferred embodiments of the present invention is provided for the purpose of better illustrating the present invention and is not intended to limit the present invention to the particular embodiments illustrated. Therefore, those skilled in the art should make insubstantial modifications and adaptations to the embodiments of the present invention in light of the above teachings and remain within the scope of the invention.

EXAMPLE 1 preparation of oxidized impurity sample 1

Taking 10g rifabutin, adding 50g absolute ethyl alcohol, dropwise adding 15g hydrogen peroxide with the mass concentration of 30%, and stirring and reacting for 5 hours at 35 ℃. And (3) dropwise adding the reaction solution into 400g of purified water, stirring for crystallization for 1h, and performing suction filtration. The filter cake is washed with 500g of purified water for 30 minutes with stirring and filtered off with suction. Pulping the filter cake with 3 times of ethyl acetate at 30 deg.C for 30min, vacuum filtering, and repeating the operation for 1 time. Heating and stirring the obtained solid for dissolving by using ethyl acetate with the weight ratio of 6 times, dripping n-heptane with the weight ratio of 12 times, cooling to 5 ℃, crystallizing, and filtering to obtain the solid. Drying under reduced pressure gave 1.2g of oxidized impurity sample as a purple red solid with a purity of 92.2%.

FIGS. 1 and 2 show the results of MS detection of a sample, in which FIG. 1 shows [ M-H ]]^-The MS detection result of 861.7 is [ M + H ] in fig. 2]⁺863.6 MS test result

EXAMPLE 2 preparation of oxidized impurity sample 2

Taking 10g of rifabutin, adding 50g of absolute ethyl alcohol, dropwise adding 10g of hydrogen peroxide with the mass concentration of 30%, and stirring and reacting for 20 hours at 20 ℃. And (3) dropwise adding the reaction solution into 500g of purified water, stirring for crystallization for 1h, and performing suction filtration. The filter cake is washed with 500g of purified water for 30 minutes with stirring and filtered off with suction. The obtained solid is dissolved by dichloromethane with 5 times weight ratio, 20g of silica gel with 100-200 meshes is added for adsorption, and a rotary evaporator is used for spin-drying. Purifying the sample by using 200-300-mesh silica gel column, wherein the volume ratio of eluent dichloromethane to methanol is 40:1, concentrating the filtrate after column chromatography to be dry, adding 10g of ethyl acetate, heating to dissolve, and dropwise adding 20g of n-hexane to obtain 2.8g of an oxidized impurity sample which is a mauve solid and has the purity of 98.1%.

EXAMPLE 3 preparation of oxidized impurity sample 3

Taking 10g rifabutin, adding 50g absolute ethyl alcohol, dropwise adding 10g hydrogen peroxide with the mass concentration of 50%, and stirring and reacting for 6h at 40 ℃. And (3) dropwise adding the reaction solution into 500g of purified water, stirring for crystallization for 1h, and performing suction filtration. The filter cake is washed with 500g of purified water for 30 minutes with stirring and filtered off with suction. The obtained solid is dissolved by dichloromethane with 5 times weight ratio, 20g of silica gel with 100-200 meshes is added for adsorption, and a rotary evaporator is used for spin-drying. Purifying the sample by using 200-300-mesh silica gel column, wherein the volume ratio of eluent dichloromethane to methanol is 20:1, concentrating the filtrate after column chromatography to be dry, adding 10g of ethyl acetate, heating to dissolve, and dropwise adding 20g of n-hexane to obtain 3.1g of an oxidized impurity sample which is a mauve solid and has the purity of 97.4%.

EXAMPLE 4 preparation of oxidized impurity sample 4

Taking 10g rifabutin, adding 40g absolute ethyl alcohol, dropwise adding 20g sodium periodate solution with the mass concentration of 25%, and stirring and reacting for 10 hours at the temperature of 30 ℃. And (3) dropwise adding the reaction solution into 400g of purified water, stirring for crystallization for 1h, and performing suction filtration. The filter cake is washed with 500g of purified water for 30 minutes with stirring and filtered off with suction. The obtained solid is dissolved by dichloromethane with 5 times weight ratio, 20g of silica gel with 100-200 meshes is added for adsorption, and a rotary evaporator is used for spin-drying. Purifying the sample by using 200-300-mesh silica gel column, wherein the volume ratio of eluent dichloromethane to methanol is 30:1, concentrating the filtrate after column chromatography to be dry, adding 10g of ethyl acetate, heating to dissolve, and then dropwise adding 20g of petroleum ether to obtain 2.1g of oxidized impurity sample which is mauve solid and has the purity of 92.4%.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A preparation method of rifabutin oxidized impurities is characterized in that the impurities are impurities generated in the preparation or storage process of rifabutin, and the structural formula of the impurities is shown as a formula II;

the preparation method specifically comprises the following steps:

2) adding an oxidant into the solution A for reaction;

2. The method of claim 1, wherein the weight ratio of the crude rifabutin product to the absolute ethanol in step 1) is 1:3 to 1: 6.

3. The preparation method according to claim 1, wherein the oxidant in step 2) is one of hydrogen peroxide or sodium periodate.

4. The preparation method according to claim 3, wherein the mass concentration of the hydrogen peroxide is 30% or 50%.

5. The preparation method according to claim 1, wherein the specific reaction conditions in step 2) are as follows: 20-60 ℃ for 2-20 h.

6. The method according to claim 1, wherein the weight ratio of ethyl acetate to solid B for the beating in the step 4) is 2:1 to 8: 1.

7. The method according to claim 1, wherein the eluent used for the column purification in step 4) is methanol or dichloromethane.

8. The method according to claim 7, wherein the volume ratio of methanol to dichloromethane is 1:10 to 1: 50.

9. The method as claimed in claim 1, wherein the weight ratio of ethyl acetate used for dissolving in step 4) to the crude rifabutin product is 1:1-5: 1.

10. The preparation method according to claim 1, wherein the nonpolar solvent in the step 4) is one or more of n-hexane, n-heptane or petroleum ether.