Method for preparing omadacycline

Abstract

Provided is a method for preparing omadacycline. The method comprises the following steps: in the presence of an inert gas, in an inert solvent, reacting a compound represented by formula III with pivalaldehyde to obtain crude omadacycline; and purification with an adsorption resin: purifying the crude omadacycline by means of the adsorption resin to obtain pure omadacycline. The method involves high yield and high purity, and is suitable for industrial production.

Description

A method for preparing omadacycline TECHNICAL FIELD

[0001] The present application belongs to the field of pharmacy, and in particular, the present application relates to a method for preparing omadacycline. BACKGROUND

[0002] Omadacycline, also known as PTK 0796, is a new semi-synthetic tetracycline developed by Paratek Pharmaceuticals, USA. It is the first successfully applied aminomethyl tetracycline variety derived from minocycline by a two-step method by Honeyman et al. Its chemical structure is shown in the following figure, and the molecular formula is C29H40N4O7, and the relative molecular weight is 556.65. Unlike tigecycline, eravacycline and other glycyl tetracyclines, its main structural feature is the C9 amino methyl modification based on the minocycline structure, which can help omadacycline overcome bacterial resistance, expand the antibacterial spectrum, and improve the pharmacokinetic properties. Omadacycline was approved for marketing by FDA in 2018, and the drug form is p-toluenesulfonate, which is used for the treatment of adult patients with acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infection (ABSSSI), and is widely used in clinical practice.

[0003] The synthesis route of omadacycline is as follows:

[0004] Omadacycline free base has poor stability and is prone to degradation to produce impurities, including oxidation impurities Impurity 1, impurities Impurity 2, impurities Impurity 3 and beta isomer impurities Impurity 4.

[0005] For the reductive amination reaction of compound III to omadacycline and the subsequent purification process, the original research compound patent WO2004091513 adds the substrate and InCl3 to the solvent, stirs for half an hour, then adds sodium triacetyl borohydride for reaction, removes the solvent after the reaction is completed, and purifies by HPLC. First, a large amount of beta isomer impurities is generated during the reaction process, and the purification is difficult later; second, the HPLC purification method is difficult to realize in industry.

[0006] Patents US2005137174, US20060287283 also purify by HPLC, patent US8946196 optimizes the HPLC purification process, but after optimization, there are still problems such as long time consumption (72h for producing 1kg of omadacycline), large solvent consumption (290L of dichloromethane, 178L of n-heptane, 54L of acetonitrile are consumed for producing 1kg of omadacycline), high solvent recovery cost, low yield (the purification yield is only 34%), which are difficult to put into actual production.

[0007] Patent CN111484424 uses palladium-carbon reduction amination, and adds CuCl2 in the reaction system to reduce the generation of β isomer impurities. After the reaction is completed, water and ammonium sulfite are added, and hydrochloric acid is used to adjust the pH to about 4.5, and dichloromethane is used for extraction for 3 times; the water layer is adjusted to about 6.5, and dichloromethane is used for extraction for 1 time; the water layer is adjusted to about 7.5, and dichloromethane is used for extraction for 4 times; after all the dichloromethane layers are combined, they are concentrated, and crystallized in a n-heptane / MTBE system to obtain omadacycline crude product with a yield of 60.5% (non-purified yield, the crude product content is 43.6% by repeating the patent method, and the purified yield is about 26.4%). Then, dichloromethane / acetone system is used for further crystallization and purification, and the product obtained has a β isomer impurity content of 1.9%, and the purification yield and product purity are not given. Although this method can effectively reduce the generation of β isomer impurities and avoid HPLC purification which is not suitable for industrialization, this method still has the following shortcomings: ①Through the purification method of the invention, omadacycline cannot be separated from the metal complex, and the final product contains a large amount of metal complex, and the omadacycline content is only 30%-60%; ②Due to the existence of a large amount of inorganic salts and complexes in the reaction solution, emulsification is serious in the extraction process, which is difficult to operate in industry, and a large amount of product is lost, and the crude product yield is less than 30%; ③Large amount of organic solvent is used (about 166L of dichloromethane, 54L of n-heptane, 12L of methyl tert-butyl ether, and 5.5L of acetone are consumed for producing 1kg of omadacycline), and the solvent cost and recovery cost are high; ④Due to the large amount of dichloromethane, a long time is needed for concentration, and the product is exposed to high temperature for a long time, which is easy to degrade; ⑤The post-treatment operation is complicated, the process is unstable, and the time consumption is long.

[0008] In view of the wide application of omadacycline, it is necessary to develop an economic and efficient, simple operation, high yield, high content, high purity and industrial feasible omadacycline preparation method. SUMMARY

[0009] An object of the present application is to provide an economic and efficient, simple operation, high yield, high content, high purity and industrial feasible omadacycline preparation method.

[0010] In a first aspect of the present application, a preparation method of omadacycline is provided, comprising the following steps:

[0011] (S1) Preparation of a crude product: reacting a compound of Formula III with pivalaldehyde to obtain a crude omadacycline;

[0012] (S2) Purification by adsorption resin: purifying the crude omadacycline by adsorption resin to obtain high-content omadacycline.

[0013] In another preferred embodiment, the compound of Formula III can be prepared by methods known in the art, for example, according to the methods in patents WO2003075857, WO2004091513, US2005137174, US8946196, CN111484424, which are incorporated herein by reference in their entirety.

[0014] In another preferred embodiment, the content of omadacycline in the crude omadacycline is ≥20%, and the content of omadacycline in the high-content omadacycline is ≥90%.

[0015] In another preferred embodiment, step (S2) specifically comprises the following steps:

[0016] (S2-1) providing a solution of the crude omadacycline in a first solvent;

[0017] (S2-2) adding the solution obtained in (S2-1) to an adsorption resin for adsorption and mixing;

[0018] (S2-3) washing with a washing agent;

[0019] (S2-4) eluting with an eluent;

[0020] (S2-5) collecting the eluate, extracting, and concentrating to obtain high-content omadacycline;

[0021] wherein, after concentration, the method optionally further comprises the steps of: freeze-drying or crystallization.

[0022] In another preferred embodiment, in step (S2-1), the first solvent is selected from the group consisting of water, C1-6alcohol solvent, C1-6ketone solvent, C2-6ether solvent, C1-6nitrile solvent, C1-6halogenated aromatic hydrocarbon solvent, amide solvent, sulfone solvent, or a combination thereof; preferably, the first solvent is selected from the group consisting of water, acetonitrile, dichloromethane, dichloroethane, tetrahydrofuran, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, methanol, ethanol, isopropanol, acetone, methyl tert-butyl ether, or a combination thereof; more preferably, the first solvent is selected from the group consisting of methanol, ethanol, acetone, acetonitrile, or a combination thereof; optionally, an acid is added to the solution obtained in (S2-1).

[0023] In another preferred embodiment, in step (S2-2), the adsorption resin is a resin having a styrene skeleton; preferably HZ chromatography resin No. 3, YKDH-3 resin, SP207SS resin, HP20SS resin, SP2MGS resin, SP20SS resin, D101 type resin, more preferably selected from HZ chromatography resin No. 3, HP20SS resin; and / or

[0024] In another preferred embodiment, in step (S2-3), the washing agent is water or acid water.

[0025] In another preferred embodiment, in step (S2-4), the eluent is an acid aqueous solution of an organic solvent, wherein the organic solvent is selected from the group consisting of C1-6alcohol solvent, C1-6ketone solvent, C2-6ether solvent, C1-6nitrile solvent, or a combination thereof; preferably selected from the group consisting of methanol, ethanol, isopropanol, acetone, tetrahydrofuran, acetonitrile, or a combination thereof; more preferably selected from the group consisting of acetone, acetonitrile, or a combination thereof.

[0026] In another preferred embodiment, in step (S2-4), the concentration of the organic solvent in the eluent is 1-50wt%, preferably 1-20wt%, more preferably 3-10wt%.

[0027] In another preferred embodiment, in steps (S2-1), (S2-3) and (S2-4), the acid is selected from the group consisting of formic acid, acetic acid, oxalic acid, trifluoroacetic acid, methanesulfonic acid, or a combination thereof; preferably the acid is selected from the group consisting of acetic acid, oxalic acid, trifluoroacetic acid, or a combination thereof;

[0028] In step (S2-1), the amount of the acid is used to make the pH of the solution 2-6.5, preferably 3-5.5, more preferably 4-5;

[0029] In step (S2-3), when the washing agent is acid water, the concentration of the acid in the acid water is 0-0.1wt%, preferably 0-0.05wt%; and / or

[0030] In step (S2-4), the concentration of the acid in the eluent is 0.01-3wt%, preferably 0.01-0.5wt%, more preferably 0.01-0.2wt%.

[0031] In another preferred embodiment, step (S1) comprises the following steps:

[0032] (S1-1) Preparation of the crude product: a compound represented by formula III is reacted with tert-pivalaldehyde in the presence of an inert gas, in an inert solvent, in the presence of a water-removing agent, an antioxidant, a reductive amination reagent, and a base, in the presence or absence of a metal salt, to obtain a crude omucycline;

[0033] wherein the metal salt is selected from the group consisting of a magnesium salt, a calcium salt, a manganese salt, or a combination thereof.

[0034] In another preferred embodiment, the metal salt is selected from the group consisting of calcium chloride, magnesium chloride, magnesium sulfate, manganese sulfate, or a combination thereof; preferably, the metal salt is selected from the group consisting of calcium chloride, magnesium chloride, or a combination thereof.

[0035] In another preferred embodiment, the antioxidant is selected from the group consisting of a sulfite, a bisulfite, a metabisulfite, ascorbic acid, or a combination thereof; preferably, the antioxidant is selected from the group consisting of ammonium sulfite, sodium sulfite, sodium bisulfite, sodium metabisulfite, ascorbic acid, or a combination thereof; more preferably, the antioxidant is selected from the group consisting of sodium sulfite, ammonium sulfite, sodium bisulfite, sodium metabisulfite, or a combination thereof.

[0036] In another preferred embodiment, the water-removing agent is selected from the group consisting of anhydrous magnesium sulfate, anhydrous calcium chloride, anhydrous sodium sulfate, or a combination thereof; preferably, the water-removing agent is selected from the group consisting of anhydrous magnesium sulfate, anhydrous calcium chloride, or a combination thereof.

[0037] In another preferred embodiment, the reductive amination reagent is selected from sodium triacetoxyborohydride and indium chloride, or hydrogen gas and palladium on carbon.

[0038] In another preferred embodiment, the base is an organic base; preferably, the organic base is selected from the group consisting of triethylamine, imidazole, N-methylimidazole, pyridine, ethanolamine, triethanolamine, DBU, or a combination thereof; more preferably, the organic base is triethylamine.

[0039] In another preferred embodiment, the molar ratio of the metal salt to the compound represented by formula III is (0.5-3): 1; preferably, the molar ratio is (1-2): 1.

[0040] In another preferred embodiment, the mass ratio of the antioxidant to the compound represented by formula III is (0.01-0.5): 1; preferably, the mass ratio is 0.05: 1.

[0041] In another preferred embodiment, the molar ratio of the water-removing agent to the compound represented by formula III is (0.5-2): 1; preferably, the molar ratio is (0.8-1.2): 1; more preferably, the molar ratio is 1: 1.

[0042] In another preferred embodiment, the molar ratio of the compound represented by formula III to tert-pivalaldehyde is 1: (2-10); preferably, the molar ratio is 1: (2-5); more preferably, the molar ratio is 1: (3-4).

[0043] In another preferred embodiment, the molar ratio of the compound of Formula III to the reductive amination reagent is 1:(2-10), preferably 1:(2-5), more preferably 1:(3-4).

[0044] In another preferred embodiment, the molar ratio of the compound of Formula III to the base is 1:(2-10), preferably 1:(2-5), more preferably 1:(3-4).

[0045] In another preferred embodiment, the inert solvent is selected from the group consisting of C1-6halogenated hydrocarbon solvents, C1-6alcohols solvents, C2-6ethers solvents, or a combination thereof, preferably dichloromethane, dichloroethane, methanol, ethanol, tetrahydrofuran, or a combination thereof.

[0046] In another preferred embodiment, in step (S1-1), the reaction temperature is 15°C or lower, preferably -15-15°C, more preferably -5-5°C.

[0047] In another preferred embodiment, in step (S1-1), the mass volume (g / mL) ratio of the compound of Formula III to the inert solvent is 1:(8-20); preferably 1:(8-15); more preferably 1:(10-12).

[0048] In another preferred embodiment, in step (S1-1) or step (S1), after the reaction is completed, the following steps are included: adding water to the reaction solution, extracting with a fourth solvent, and concentrating to obtain the crude omadacycline.

[0049] In another preferred embodiment, the fourth solvent is selected from the group consisting of C1-6halogenated hydrocarbon solvents, aromatic hydrocarbon solvents, C1-6esters solvents, C2-6ethers solvents, or a combination thereof; preferably, selected from the group consisting of dichloromethane, dichloroethane, methyl tert-butyl ether, isopropyl ether, toluene, ethyl acetate, isopropyl acetate, or a combination thereof; more preferably, selected from the group consisting of methyl tert-butyl ether, dichloromethane, or a combination thereof.

[0050] In another preferred embodiment, the extraction temperature is room temperature, preferably 25°C or lower.

[0051] In another preferred embodiment, the extraction is further preceded by a filtration step.

[0052] In another preferred embodiment, the extraction process includes adjusting the pH of the aqueous layer to 7-12, preferably 7-10; adjusting the pH using an inorganic or organic base; wherein the inorganic base is selected from the group consisting of: ammonia, potassium hydroxide, sodium hydroxide, lithium hydroxide, potassium phosphate, sodium phosphate, ammonium phosphate, ammonium carbonate, lithium carbonate, potassium carbonate, sodium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, or combinations thereof; preferably potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonia, or combinations thereof; and the organic base is selected from the group consisting of: triethylamine, imidazole, N-methylimidazolium, pyridine, ethanolamine, triethanolamine, DBU, or combinations thereof; preferably triethylamine.

[0053] In another preferred embodiment, the concentration temperature is below 30°C, more preferably 0-20°C.

[0054] In a second aspect of the present invention, a method for purifying omalicycline is provided, comprising the following steps:

[0055] (S2-1) Provide a solution of crude omacycline in a first solvent;

[0056] (S2-2) Add the solution obtained in (S2-1) to the adsorption resin for adsorption and mixing;

[0057] (S2-3) Wash with detergent;

[0058] (S2-4) Elute with eluent;

[0059] (S2-5) Collect the eluent, extract, concentrate, and obtain high-content omacycline;

[0060] The concentration process may also include optional steps such as freeze drying or crystallization.

[0061] In another preferred embodiment, before extraction in step (S2-5), the collected eluent is concentrated to a volume of 1 to 50 times the mass of crude omacycline, more preferably 10 to 30 times the mass of the remaining eluent.

[0062] In another preferred embodiment, in step (S2-5), before extraction, the pH of the resulting eluent is adjusted to 7-12 using an organic base, preferably 7-9, wherein the organic base is selected from the group consisting of triethylamine, imidazole, N-methylimidazolium, pyridine, ethanolamine, triethanolamine, DBU, or combinations thereof; preferably selected from the group consisting of triethylamine, ethanolamine, triethanolamine, or combinations thereof.

[0063] In another preferred embodiment, in step (S2-5), the extraction solvent is selected from the group consisting of C1-6halogenated hydrocarbon solvents, C1-6ether solvents, aromatic hydrocarbon solvents, C1-6ester solvents, or a combination thereof; preferably selected from the group consisting of dichloromethane, dichloroethane, methyl tert-butyl ether, isopropyl ether, toluene, ethyl acetate, isopropyl acetate, or a combination thereof; more preferably selected from the group consisting of methyl tert-butyl ether, dichloromethane, or a combination thereof.

[0064] In another preferred embodiment, in step (S2-5), the concentration temperature is lower than 30°C.

[0065] In another preferred embodiment, in step (S2-5), the crystallization solvent is selected from the group consisting of C1-8hydrocarbon solvents, C2-6ether solvents, C1-6ketone solvents, or a combination thereof; preferably selected from the group consisting of n-heptane, methyl tert-butyl ether, isopropyl ether, acetone, or a combination thereof; more preferably selected from the group consisting of n-heptane, methyl tert-butyl ether, isopropyl ether, or a combination thereof.

[0066] In another preferred embodiment, in step (S2-5), the mass / volume ratio (g / mL) of the solid after concentration to the crystallization solvent is 1:(5-100); preferably 1:(10-30).

[0067] In another preferred embodiment, after the crystallization, the obtained solid is further dried, and the drying temperature is lower than 40°C, preferably by vacuum drying.

[0068] In another preferred embodiment, the crystallization temperature is 0-25°C.

[0069] In another preferred embodiment, the purity of the crude omadacycline is 50%-95%.

[0070] In another preferred embodiment, the content of omadacycline in the crude omadacycline is ≥20%, preferably 20%-85%, more preferably 30%-70%.

[0071] In another preferred embodiment, the purity of the high-content omadacycline is ≥90%, preferably ≥95%.

[0072] In another preferred embodiment, the content of omadacycline in the high-content omadacycline is ≥90%, preferably ≥95%, more preferably ≥98%.

[0073] In a third aspect of the present application, a preparation method of omadacycline p-toluenesulfonate is provided, comprising the steps of:

[0074] (S1) preparation of a crude product: reacting a compound shown in formula III with tert-pentanal to obtain a crude omadacycline;

[0075] (S2) Adsorption resin purification: the crude omadacycline is purified by adsorption resin to obtain high content omadacycline;

[0076] (S3) The high content omadacycline is salted with p-toluenesulfonic acid to obtain omadacycline p-toluenesulfonate.

[0077] In another preferred embodiment, step (S1) comprises the following steps:

[0078] (S1-1) The compound shown in formula III is reacted with tert-penyl aldehyde in the presence of inert gas, in inert solvent, in the presence of water removal agent, antioxidant, reductive amination reagent and base, in the presence or absence of metal salt to obtain crude omadacycline;

[0079] The metal salt is selected from the group consisting of magnesium salt, calcium salt, manganese salt, or a combination thereof.

[0080] It should be understood that, within the scope of the present application, each of the technical features described above and each of the technical features described in detail below (such as the examples) can be combined with each other to form new or preferred technical solutions. Due to the limited space, they will not be listed one by one here. DETAILED DESCRIPTION

[0081] The inventors have made extensive and in-depth research and for the first time provided a brand new preparation and purification method of omadacycline. Specifically, in the method of the present application, a metal salt, such as magnesium chloride and calcium chloride, is used in the reductive amination step, which effectively reduces the generation of various impurities; in the purification process of crude omadacycline, adsorption resin is used for purification, which effectively separates omadacycline from metal complexes and removes various impurities, thereby obtaining omadacycline with high content and high purity at high yield. Based on this, the inventors completed the present application.

[0082] Preparation method of omadacycline

[0083] The present application provides an economical and efficient, simple operation, high yield, high content, high purity, and industrially feasible preparation method of omadacycline. In particular, the purification method of the present application uses adsorption resin to separate omadacycline from metal complexes, thereby obtaining purified high content omadacycline.

[0084] Specifically, the method provided by the present application comprises two steps:

[0085] (1) Preparation of crude omadacycline: the compound shown in formula III is reacted with tert-penyl aldehyde in the presence of inert gas, in inert solvent, in the presence of water removal agent, antioxidant, reductive amination reagent and base, in the presence or absence of metal salt to obtain crude omadacycline;

[0086] (2) Purification of the crude omadacycline: the crude omadacycline is purified by adsorption resin to obtain high content omadacycline.

[0087] The compound of formula III used in the present application is not particularly limited and can be obtained by a method disclosed in a prior art patent or a method commonly used in the art, for example, prepared according to the method in patents WO2003075857, WO2004091513, US2005137174, US8946196, CN111484424, which are incorporated herein by reference in their entirety.

[0088] In another preferred embodiment, the method of the present application can effectively remove the oxidized impurities in omadacycline.

[0089] In step (1), the inert gas used is not particularly limited and is an inert gas commonly used in the art, for example, nitrogen, helium, argon, etc. The inert solvent used is not particularly limited and is an inert solvent commonly used in the art, for example, a C1-6halogenated hydrocarbon solvent, a C1-6alcohol solvent, a C2-6ether solvent, or a combination thereof.

[0090] The reaction time and temperature of this step are not particularly limited, and generally, the reaction temperature of this step is near room temperature to low temperature, for example, 15°C or lower. The reaction time is 1-36h.

[0091] In a preferred embodiment, the water removal agent used in this step is not particularly limited and includes, but is not limited to, anhydrous magnesium sulfate, anhydrous calcium chloride, anhydrous sodium sulfate, or a combination thereof; wherein the molar ratio of the water removal agent to the compound of formula III is (0.5-2):1, preferably (0.8-1.2):1, and more preferably 1:1.

[0092] In a preferred embodiment, the antioxidant used in this step is not particularly limited and includes, but is not limited to, a sulfite, a bisulfite, a metabisulfite, ascorbic acid, or a combination thereof; wherein the mass ratio of the antioxidant to the compound of formula III is (0.01-0.5):1, preferably 0.05:1.

[0093] In a preferred embodiment, the metal salt used in this step is not particularly limited and includes, but is not limited to, a magnesium salt, a calcium salt, a manganese salt, a copper salt, or a combination thereof; preferably calcium chloride, magnesium chloride, magnesium sulfate, manganese sulfate, or a combination thereof; wherein the molar ratio of the metal salt to the compound of formula III is (0.5-3):1, preferably (1-2):1.

[0094] In one preferred embodiment, the reducing aminating reagent used in this step is not particularly limited, and includes, but is not limited to, sodium triacetoxyborohydride and indium chloride system, or hydrogen and palladium-carbon system, wherein the molar ratio of the compound of formula III to the reducing aminating reagent is 1:(2-10), preferably 1:(2-5), and more preferably 1:(3-4).

[0095] In one preferred embodiment, the base used in this step is not particularly limited, and includes, but is not limited to, an organic base, preferably the organic base is selected from the group consisting of triethylamine, imidazole, N-methylimidazole, pyridine, ethanolamine, triethanolamine, DBU, or a combination thereof; wherein the molar ratio of the compound of formula III to the base is 1:(2-10), preferably 1:(2-5), and more preferably 1:(3-4).

[0096] In one preferred embodiment, the molar ratio of the compound of formula III to pivalaldehyde used in this step is not particularly limited, and includes, but is not limited to, 1:(2-10), preferably 1:(2-5), and more preferably 1:(3-4).

[0097] This step further comprises the step of adding water to the reaction solution after the reaction is completed, extracting with a fourth solvent, and concentrating to obtain the crude omadacycline.

[0098] In step (2), the crude omadacycline obtained in step (1) is purified by adsorption resin, and the purification process comprises dissolving the crude omadacycline, adding the adsorption resin to adsorb and mix the sample, washing with a washing agent, eluting with an eluting agent, collecting the eluate, extracting, and concentrating to obtain the high-content omadacycline.

[0099] After concentration, the process optionally further comprises the steps of freeze-drying or crystallization.

[0100] The adsorption resin used in this step is not particularly limited, and the names of various manufacturers are different, and preferably the resin has a styrene skeleton; for example, HZ chromatographic resin No. 3, YKDH-3 resin, SP207SS resin, HP20SS resin, SP2MGS resin, SP20SS resin, D101 resin, and more preferably, the adsorption resin is selected from HZ chromatographic resin No. 3 and HP20SS resin. The particle size of the adsorption resin is 10-500 μm, preferably 50-400 μm, and more preferably 75-300 μm; and the adsorption capacity of the adsorption resin is 0.1 g-30 g (crude omadacycline) / 100 g of resin.

[0101] In one specific embodiment, the washing agent used is acid water with an acid content of 0-0.1 wt%, and the acid is not particularly limited and is commonly used in the art, and is preferably formic acid, acetic acid, oxalic acid, trifluoroacetic acid, methanesulfonic acid, or a combination thereof.

[0102] The sign of completion of the washing is that the conductivity of the washing liquid obtained after the washing is the same as the conductivity of the washing agent used.

[0103] In one specific embodiment, the eluent used is an acid aqueous solution of an organic solvent, wherein the concentration of the organic solvent is 1-50 wt%, and the concentration of the acid is 0.01-3 wt%.

[0104] Compared with the prior art, the main advantages of the present application include:

[0105] 1. By adding metal salt in the reaction system, the generation of various impurities such as β-isomer impurities and oxidation impurities can be effectively reduced, the content of β-isomer in the reaction liquid is reduced from 7% to below 1%, the oxidation impurities are reduced from 6% to below 2%, the conversion rate is improved, and the burden of subsequent purification is reduced;

[0106] 2. Using adsorption resin purification, omadacycline can be effectively separated from metal complexes, the content of the product is increased from 20%-60% to above 98%, and various impurities can be removed, the whole purification process is simple in operation, low in product loss, small in organic solvent consumption, stable in process, and feasible in industry;

[0107] 3. The purification effect is good, the purity of the obtained omadacycline reaches above 92%, and the content of the remaining impurities except β-isomer can be controlled below 0.1%, and the content of oxidation impurities can be reduced to ND.

[0108] 4. The yield is high, and compared with the existing process, the crude product yield is increased from 26% to above 80%, the purification yield is increased from 41% to above 80%, and preferably, can reach above 90%.

[0109] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. The experimental methods in the following examples without specific conditions are usually carried out according to the conventional conditions or the conditions suggested by the manufacturers. Unless otherwise specified, the percentages and parts are calculated by weight.

[0110] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to one skilled in the art. In addition, any method and material similar or equivalent to those described can be applied to the method of the present application. The preferred implementation methods and materials described herein are only used for demonstration.

[0111] Example 1: Preparation of omadacycline crude product (adding metal salt)

[0112] Under argon protection, add anhydrous magnesium sulfate (1.87 g, 15.5 mmol), sodium sulfite (0.40 g), calcium chloride (1.72 g, 15.5 mmol), indium chloride (3.42 g, 15.5 mmol), dichloroethane (80 mL) into a reaction flask, stir, cool to -5-5 °C, add triethylamine (4.40 g, 43.4 mmol), tert-pivaldehyde (4.01 g, 46.5 mmol) and compound III (8.0 g, 15.5 mmol), control the temperature to -5-5 °C, stir for 1 hour; control the temperature to -5-5 °C, add sodium triacetoxyborohydride (8.22 g, 38.8 mmol), stir the reaction at -5-5 °C, take sample every 1 hour to detect until the reaction is completed, take the reaction liquid to perform HPLC detection, the content of omadacycline is 92.3%, the content of β isomer impurity is 0.6%, and the content of oxidation impurity is 0.7%.

[0113] After the reaction is completed, add acetone (1 mL) to quench, perform suction filtration (add diatomite to assist filtration), collect the filtrate, and concentrate to remove the solvent below 10 °C. Then add ice water (80 mL) to stir and dissolve, control the temperature to be below 10 °C, drop 20% sodium hydroxide solution to adjust pH to 9-10, stir for 30 minutes, recheck the pH value, do not change, add methyl tert-butyl ether (80 mL) to extract, separate, collect the methyl tert-butyl ether layer, extract the water layer with methyl tert-butyl ether (8 mL) once, combine the methyl tert-butyl ether layers, and concentrate to dryness under pressure below 10 °C to obtain 13.06 g of omadacycline crude product (content 55.5%, purity 93.1%, wherein the content of β isomer impurity is 0.9%, and the content of oxidation impurity is 0.7%), the purified yield is 83.9%.

[0114] Example 2: Preparation of omadacycline crude product (add metal salt)

[0115] Under argon protection, add anhydrous magnesium sulfate (1.87 g, 15.5 mmol), sodium sulfite (0.40 g), calcium chloride (1.72 g, 15.5 mmol), indium chloride (3.42 g, 15.5 mmol), dichloroethane (80 mL) into a reaction flask, stir, cool to -5-5 °C, add triethylamine (4.40 g, 43.4 mmol), tert-pivaldehyde (4.01 g, 46.5 mmol) and compound III (8.0 g, 15.5 mmol), control the temperature to -5-5 °C, stir for 1 hour; control the temperature to -5-5 °C, add sodium triacetoxyborohydride (8.22 g, 38.8 mmol), stir the reaction at -5-5 °C, take sample every 1 hour to detect until the reaction is completed, take the reaction liquid to perform HPLC detection, the content of omadacycline is 92.3%, the content of β isomer impurity is 0.6%, and the content of oxidation impurity is 0.7%.

[0116] After the reaction was completed, acetone (1 mL) was added to quench the reaction, and the mixture was filtered (with diatomite to aid filtration). The filtrate was collected and concentrated to remove the solvent at a temperature below 10 °C. Then, ice water (80 mL) was added to the mixture, which was stirred to dissolve. Triethylamine was added dropwise to adjust the pH to 9-10 at a temperature below 10 °C. The pH was rechecked after the mixture was stirred for 30 minutes. Dichloromethane (80 mL) was added to the mixture, which was separated into two layers. The dichloromethane layer was collected, and the water layer was extracted with dichloromethane (8 mL) once. The dichloromethane layers were combined and concentrated under pressure at a temperature below 20 °C to dryness to obtain 12.9 g of crude omadacycline (content: 54.9%, purity: 91.5%, content of β isomer impurities: 1.0%, content of oxidation impurities: 1.2%), which was purified to give omadacycline with a yield of 82.0% based on the purity.

[0117] Example 3: Preparation of crude omadacycline (without addition of metal salt)

[0118] Under argon protection, ammonium sulfite (0.40 g), indium chloride (3.42 g, 15.5 mmol), and dichloroethane (80 mL) were added to a reaction bottle, which was stirred and cooled to a temperature of -5-5 °C. Triethylamine (4.40 g, 43.4 mmol), tert-pivaldehyde (4.01 g, 46.5 mmol), and compound III (8.0 g, 15.5 mmol) were added to the mixture, which was stirred for 1 hour while the temperature was controlled at -5-5 °C. Sodium triacetoxyborohydride (8.22 g, 38.8 mmol) was added to the mixture, which was stirred at a temperature of -5-5 °C. The reaction was sampled and checked every 1 hour until the reaction was completed. The reaction liquid was subjected to HPLC detection, which showed that the content of omadacycline was 80.8%, the content of β isomer impurities was 6.7%, and the content of oxidation impurities was 6.4%.

[0119] After the reaction was completed, acetone (1 mL) was added to quench the reaction, and the mixture was filtered (with diatomite to aid filtration). The filtrate was collected and concentrated to remove the solvent at a temperature below 10 °C. Then, ice water (80 mL) was added to the mixture, which was stirred to dissolve. Triethylamine was added dropwise to adjust the pH to 9-10 at a temperature below 10 °C. The pH was rechecked after the mixture was stirred for 30 minutes. Dichloromethane (80 mL) was added to the mixture, which was separated into two layers. The dichloromethane layer was collected, and the water layer was extracted with dichloromethane (8 mL) once. The dichloromethane layers were combined and concentrated under pressure at a temperature below 20 °C to dryness to obtain 12.9 g of crude omadacycline (content: 54.9%, purity: 91.5%, content of β isomer impurities: 1.0%, content of oxidation impurities: 1.2%), which was purified to give omadacycline with a yield of 82.0% based on the purity.

[0120] Example 4: Purification of crude omadacycline

[0121] Take the crude omilancil 5g (content 55.5%, purity 93.1%, oxidized impurity content 0.7%), add 15 mL water, drop trifluoroacetic acid until the solution is clear, the solution pH is 4-4.5, pour the obtained solution into HP20SS resin (particle size 75-150 μm, filling amount 100 g), rinse with 0.01% trifluoroacetic acid aqueous solution until the conductivity of the effluent is consistent with that of the used eluent, after rinsing, elute with trifluoroacetic acid acetonitrile-water solution (containing 0.1% trifluoroacetic acid, 5% acetonitrile) until no omilancil is detected in the effluent by TLC. Collect the eluent, concentrate the eluent to about 100 mL using nanofiltration, adjust the pH to 7.5-8.0 with triethylamine, extract twice with 100 mL dichloromethane, combine the organic phases, concentrate to non-flowability at 20°C under reduced pressure, then freeze-dry to obtain 2.55 g of high-content omilancil (content 98.7%, purity 98.8%, oxidized impurity content ND), the purification yield is 90.7%.

[0122] Resin recovery treatment: first, rinse the resin with triethylamine acetonitrile-water solution (containing 0.5% triethylamine, 50% acetonitrile) until the pH is alkaline; then rinse the resin with acetic acid acetonitrile-water solution (containing 1% acetic acid, 50% acetonitrile) until the pH is acidic; finally, rinse the resin with purified water until the pH is neutral. The treated resin can be used again.

[0123] Example 5: Purification of crude omilancil

[0124] Take the crude omilancil 5g (content 54.9%, purity 91.5%, oxidized impurity content 1.2%), add 20 mL ethanol-water solution (ethanol: water = 1:4), drop acetic acid until the solution is clear, the solution pH is 4-4.5, pour the obtained solution into HZ chromatography resin No. 3 (particle size 75-150 μm, filling amount 100 g), rinse with 0.02% acetic acid aqueous solution until the conductivity of the effluent is consistent with that of the used eluent, after rinsing, elute with acetic acid acetone-water solution (containing 0.1% acetic acid, 3% acetone) until no omilancil is detected in the effluent by TLC. Collect the eluent, concentrate the eluent to about 100 mL using nanofiltration, adjust the pH to 8-8.5 with ethanolamine, extract twice with 100 mL dichloromethane, combine the organic phases, concentrate to non-flowability at 20°C under reduced pressure, stop the concentration. Add 80 mL n-heptane to the concentrated solution, stir at 20°C to crystallize, filter, rinse the filter cake with n-heptane, and dry the filter cake to constant weight at 35°C under vacuum to obtain 2.52 g of high-content omilancil (content 98.4%, purity 98.4%, oxidized impurity content ND), the purification yield is 90.3%.

[0125] Example 6: Purification of crude omilancil

[0126] Take the crude omilancil 5g (content 51.1%, purity 82.7%, oxidized impurity content 6.2%), add 20 mL acetonitrile-water solution (acetonitrile: water = 1:4), drop acetic acid until the solution is clear, the solution pH is 4-4.5, pour the obtained solution into HZ chromatography resin No. 3 (particle size 150-300 μm, filling amount 100 g), rinse with water until the conductivity of the effluent is consistent with that of the water used, after rinsing, elute with acetic acid acetonitrile-water solution (containing 0.1 wt% acetic acid, 5 wt% acetonitrile) until no omilancil is detected in the effluent by TLC. Collect the eluent, concentrate the eluent to about 100 mL using nanofiltration, adjust the pH to 7.5-8 with triethylamine, extract twice with 100 mL methyl tert-butyl ether each time, combine the organic phases, concentrate under reduced pressure at 20°C until no liquid is discharged, obtain 2.28 g high content omilancil (content 98.6%, purity 96.0%, oxidized impurity content ND), the purification yield is 88.0%.

[0127] Example 7: Purification of crude omilancil

[0128] Take the crude omilancil 1.83 kg (content 44.5%, purity 90.3%, oxidized impurity content 1.4%), add 6 L water, add acetic acid until the solution is clear, the solution pH is 4.5-5, pour the obtained solution into HZ chromatography resin No. 3 (particle size 75-150 μm, filling amount 15 kg); then rinse with purified water until the conductivity of the effluent is consistent with that of the purified water, after rinsing, elute with acetic acid acetonitrile-water solution (containing 0.02 wt% acetic acid, 5 wt% acetonitrile) until no omilancil is detected in the effluent by TLC. Collect the eluent (about 200 L), concentrate the eluent to about 40 L using nanofiltration, adjust the pH to 8-8.5 with ethanolamine, extract twice with 40 L dichloromethane each time, combine the organic phases, concentrate under reduced pressure at 20°C until no flow is observed, then freeze-dry to obtain 816.0 g high content omilancil (content 99.8%, purity 94.3%, oxidized impurity content ND), the purification yield is 83.6%.

[0129] Example 8: Preparation of omilancil p-toluenesulfonate

[0130] Under argon protection, add high content omilancil prepared in Example 4 (1 g, 1.80 mmol), isopropanol (10 mL) to a reaction bottle and stir; add p-toluenesulfonic acid monohydrate (0.41 g, 2.2 mmol), control the temperature at 20-25°C, stir for 4 hours; filter, rinse the filter cake with isopropanol (1 mL), vacuum dry the filter cake at 0-10°C to constant weight, obtain 1.21 g omilancil p-toluenesulfonate, yield 92.4%, purity 98.9%.

[0131] Comparative Example 1: Comparison of reaction effects of different metal salts

[0132] Reaction conditions: Under argon protection, add a drying agent, anhydrous magnesium sulfate (1.87 g, 15.5 mmol), sodium sulfite (0.40 g), a metal salt (15.5 mmol), indium chloride (3.42 g, 15.5 mmol), dichloroethane (80 mL) in a reaction bottle, stir, cool to -5-5°C, add triethylamine (4.40 g, 43.4 mmol), tert-pivaldehyde (4.01 g, 46.5 mmol) and compound III (8.0 g, 15.5 mmol), control the temperature to -5-5°C, stir for 1 hour; control the temperature to -5-5°C, add sodium triacetoxyborohydride (8.22 g, 38.8 mmol), stir the reaction at -5-5°C, take samples every 1 hour for detection until the reaction is complete, take the reaction liquid for HPLC detection.

[0133] The HPLC results are as follows (peak area %):

[0134] As can be seen, the addition of a metal salt in the reaction system can effectively inhibit the generation of β-isomer impurities, oxidation impurities and the like.

[0135] Comparative Example 2: Purification of omadacycline crude product (according to the method of CN111484424)

[0136] Take omadacycline crude product 5 g (content 55.3%, purity 93.8%, oxidation impurity content 1.7%), add 70 mL ice water, control temperature <15°C, adjust PH=4.5±0.2 with hydrochloric acid, under nitrogen protection, control temperature <15°C, add 70 mL dichloromethane, after adding, stir for ten minutes, then stand for separation, retain the water layer and emulsion layer, extract 3 times. Collect and store the dichloromethane layer separately; control temperature <15°C, adjust PH=6.5±0.2, extract with 70 mL dichloromethane x1; 510°C store the dichloromethane layer; control temperature <15°C, adjust PH=7.5±0.2, extract with 70 mL dichloromethane x4, combine with the dichloromethane layer of the previous step. Concentrate under vacuum to 8% 10% of the initial volume at less than 25°C, wash with 20 mL dichloromethane once (still concentrate to 8% 10% of the initial volume). Cool the system to <5°C, control temperature <5°C, add 350 mL n-heptane, 70 mL methyl tert-butyl ether. After adding, control temperature 0-5°C, stir for 2 h, filter under nitrogen protection. Wash the filter cake with a mixture of n-heptane / methyl tert-butyl ether (16 mL / 7 mL), after filtering, blow for 1 h under nitrogen. Control temperature 25°C, vacuum dry to constant weight.

[0137] Into a reaction vessel was added 25 mL of dichloromethane, and the mixture was stirred and cooled to 10-15 °C. The solid obtained in the previous step was added, and the mixture was stirred for 30 min to ensure complete dissolution. Into the clear reaction mixture was added 25 mL of acetone dropwise while maintaining the temperature at 10-15 °C. After the addition was completed, the mixture was stirred for 10 min. 0.1 g of seed crystal was added to the mixture, and the mixture was slowly crystallized while stirring. After the suspension was stirred for 3 h, it was filtered. The filter cake was washed with dichloromethane / acetone (1:1), and then dried at 35-40 °C under vacuum until the weight was constant. Thus, 2.04 g of omadacycline was obtained (content 55.7%, purity 97.3%, and oxidized impurity content 0.4%), and the purification yield was 41.1%.

[0138] The content of the final omadacycline was only 55.7%, and most of the omadacycline was not separated from the metal complex.

[0139] Table 1. Comparative data of Example 4 and Comparative Example 2

[0140] It can be seen that, compared with the traditional purification method, the resin purification process of the present application can significantly improve the content of omadacycline, separate omadacycline from the complex, and improve the purification yield and product purity.

[0141] All the documents mentioned in the present application are incorporated herein by reference as if each document were individually incorporated. In addition, it should be understood that various changes and modifications can be made to the present application by those skilled in the art upon reading the above description of the present application, and such equivalent forms are also within the scope of the appended claims.

Claims

1. A process for the preparation of omadacycline, characterized in that, comprising the steps of: (S1) Preparation of the crude product: reacting the compound of formula III with pivalaldehyde to obtain the crude omadacycline; (S2) Purification by adsorption resin: purifying the crude omadacycline by adsorption resin to obtain high content omadacycline.

2. The method of claim 1, wherein, The content of omadacycline in the crude omadacycline is ≥20%, and the content of omadacycline in the high content omadacycline is ≥90%.

3. The method of claim 1, wherein, The step (S2) specifically comprises the following steps: (S2-1) providing a solution of the crude omadacycline in a first solvent; (S2-2) adding the solution obtained in (S2-1) into an adsorption resin for adsorption and mixing; (S2-3) washing with a washing agent; (S2-4) eluting with an eluent; (S2-5) collecting the eluent, extracting, and concentrating to obtain the high content omadacycline; Optionally, after the concentration, the step of freeze-drying or crystallization is further included.

4. The method of claim 1 or 3, wherein, In the step (S2-1), the first solvent is selected from the group consisting of water, C1-6alcohol solvent, C1-6ketone solvent, C2-6ether solvent, C1-6nitrile solvent, C1-6halogenated aromatic hydrocarbon solvent, amide solvent, sulfone solvent, or a combination thereof; preferably, the first solvent is selected from the group consisting of water, acetonitrile, dichloromethane, dichloroethane, tetrahydrofuran, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, methanol, ethanol, isopropanol, acetone, methyl tert-butyl ether, or a combination thereof; more preferably, the first solvent is selected from the group consisting of methanol, ethanol, acetone, acetonitrile, or a combination thereof; optionally, an acid is added to the solution obtained in (S2-1); and / or In the step (S2-2), the adsorption resin is a resin with a styrene skeleton; preferably, HZ chromatography resin No. 3, YKDH-3 resin, SP207SS resin, HP20SS resin, SP2MGS resin, SP20SS resin, D101 resin, more preferably, selected from HZ chromatography resin No. 3 and HP20SS resin; and / or In the step (S2-3), the washing agent is water or acid water; and / or In the step (S2-4), the eluent is an acid aqueous solution of an organic solvent, wherein the organic solvent is selected from the group consisting of C1-6alcohol solvent, C1-6ketone solvent, C2-6ether solvent, C1-6nitrile solvent, or a combination thereof; preferably, selected from the group consisting of methanol, ethanol, isopropanol, acetone, tetrahydrofuran, acetonitrile, or a combination thereof; more preferably, selected from the group consisting of acetone, acetonitrile, or a combination thereof; and / or the concentration of the organic solvent in the eluent is 1-50 wt%, preferably 1-20 wt%, more preferably 3-10 wt%.

5. The method of claim 4, wherein, In the steps (S2-1), (S2-3), and (S2-4), the acid is selected from the group consisting of formic acid, acetic acid, oxalic acid, trifluoroacetic acid, methanesulfonic acid, or a combination thereof; preferably, the acid is selected from the group consisting of acetic acid, oxalic acid, trifluoroacetic acid, or a combination thereof; In the step (S2-1), the acid is used in an amount such that the pH of the solution is 2-6.5, preferably 3-5.5, more preferably 4-5; In step (S2-3), when the washing agent is acid water, the concentration of the acid in the acid water is 0-0.1 wt%, preferably 0-0.05 wt%; In step (S2-4), the concentration of the acid in the eluent is 0.01-3 wt%, preferably 0.01-0.5 wt%; more preferably 0.01-0.2 wt%.

6. The method of claim 1, wherein, Step (S1) comprises the following steps: (S1-1) reacting a compound of formula III with pivalaldehyde in the presence of an inert gas, in an inert solvent, in the presence of a water scavenger, an antioxidant, a reductive amination reagent, and a base, in the presence or absence of a metal salt, to obtain a crude omadacycline; wherein the metal salt is selected from the group consisting of a magnesium salt, a calcium salt, a manganese salt, or a combination thereof.

7. A method of purifying omadacycline, comprising: comprises the following steps: (S2-1) providing a solution of the crude omadacycline in a first solvent; (S2-2) adding the solution obtained in (S2-1) to an adsorption resin for adsorption; (S2-3) washing with a washing agent; (S2-4) eluting with an eluent; (S2-5) collecting the eluate, extracting, and concentrating to obtain high-content omadacycline; wherein after concentration, the process optionally further comprises the steps of freeze-drying or crystallization.

8. A process for the preparation of omadacycline p-toluenesulfonic acid salt characterized in that, comprises the following steps: (S1) preparing a crude product by reacting a compound of formula III with pivalaldehyde to obtain a crude omadacycline; (S2) purifying the crude omadacycline by passing it through an adsorption resin to obtain high-content omadacycline; (S3) forming a salt of the high-content omadacycline with p-toluenesulfonic acid to obtain omadacycline p-toluenesulfonate.

9. The method of claim 8, wherein, Step (S1) comprises the following steps: reacting a compound of formula III with pivalaldehyde in the presence of an inert gas, in an inert solvent, in the presence of a water scavenger, an antioxidant, a reductive amination reagent, and a base, in the presence or absence of a metal salt, to obtain a crude omadacycline; wherein the metal salt is selected from the group consisting of a magnesium salt, a calcium salt, a manganese salt, or a combination thereof.

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