Synthesis process

Abstract

An optimized method for synthesizing dalbavancin is provided, in which an organic anti-solvent, such as tert-butyl methyl ether (TBME) or dimethoxyethane (DME), is used to precipitate the esterification product of A-40926.

Description

Technical Field

[0001] (Field of the Invention) The present invention relates to a method for synthesizing dalbavancin.

Background Art

[0002] (Background) Dalbavancin is a semi-synthetic lipoglycopeptide that exhibits a bactericidal effect by disrupting the biosynthesis of the cell wall. Dalbavancin binds to the D-alanyl-D-alanine residues on the growing peptidoglycan chain, preventing peptide transfer and thereby inhibiting the elongation of peptidoglycan and cell wall formation.

[0003] Dalbavancin is produced by fermentation of a Nonomuraea selected strain that generates the natural glycopeptide complex A-40926. Subsequently, this precursor is selectively esterified at the carboxyl group in the sugar moiety of the precursor, the peptidyl carboxyl group of the precursor is amidated, and the ester of the N-acylaminoglucuronic acid carboxyl group is saponified. This product is a mixture of compounds of two closely related structural families (A and B), which can be further subdivided into a total of five subtypes (see the table below).

[0004]

Chemical Formula

[0005] <于

Table 1

[0006] There are various methods for converting the precursor A-40926 to dalbavancin, all of which include an esterification step, an amidation step, and a hydrolysis step. U.S. Patent No. 6,900,175 (Patent Document 1) describes an esterification step using a sulfuric acid methanol solution at 0°C, followed by pH adjustment with triethylamine to precipitate the zwitterionic form of the product, thereby isolating the product, and then centrifuging and vacuum oven drying. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent No. 6900175 [Overview of the project]

[0008] (overview) The present invention provides an alternative and improved process for synthesizing dalbavansine from precursor A-40926. The process comprises the following steps:

[0009] (i) A step of providing a compound of formula I, also known as A-40926, or a salt thereof.

[0010] [ka]

[0011] (ii) A step of performing an esterification step to obtain the compound of formula II.

[0012] [ka]

[0013] Here, X may be Cl, Br, HSO4, SO4, H2PO4, HPO4, PO4, NO3, F3CCO2, F3CSO3, H3CSO3, or p-toluenesulfonate, and R may be a C1-C6 alkyl group.

[0014] (iii) A step of forming a precipitate by adding an appropriate amount of tert-butyl methyl ether or dimethoxyethane. (iv) Step of adding 3-(dimethylamino)-1-propylamine to the precipitate in order to perform peptide coupling to obtain the compound of formula III.

[0015] [Chemical formula]

[0016] Here, R may be a C1-C6 alkyl group. (v) Step of performing an ester hydrolysis step to obtain dalbavancin or a salt thereof. [Mode for Carrying Out the Invention]

[0017] (Detailed Disclosure) In the process described in the present invention, dalbavancin is prepared from the naturally occurring compound A-40926. A-40926 is represented by the following formula I. Dalbavancin is prepared through converting one of the two carboxyl groups in A-40926 into (dimethylamino) propylamide.

[0018] [[ID=Z8]]In the process according to the present invention, dalbavancin is synthesized from the compound of formula I.

[0019] [Chemical formula]

[0020] As can be seen from formula I, A-40926 has two carboxyl groups, one peptidyl carboxyl group, and one N-acylaminoglucuronic acid group. The peptidyl carboxyl group is amidated to obtain dalbavancin. Therefore, selective alkyl esterification of the N-acylaminoglucuronic acid group is necessary to protect the N-acylaminoglucuronic acid group from amidation, and the first step of the synthesis process is an esterification step to obtain the compound of formula II.

[0021] [ka]

[0022] The esterification process is carried out by adding A-40926 to an alcohol solution containing an acid. The acid can be any of the following: HCl, HBr, H2SO4, H3PO4, HNO3, F3CCO2H, F3CSO3H, H3CSO3H, or p-toluenesulfonic acid.

[0023] Therefore, depending on the acid used, X in formula II can be Cl, Br, HSO4, SO4, H2PO4, HPO4, PO4, NO3, F3CCO2, F3CSO3, H3CSO3, or p-toluenesulfonate.

[0024] The term “alcoholic solution” is understood to mean a solution containing alcohol and at most 2% water. In some embodiments, this can be up to 1.9%, 1.8%, 1.7%, 1.6%, 1.5%, 1.4%, 1.3%, 1.2%, 1.1%, 1.0%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, or 0.05%.

[0025] In one embodiment, the amount of water in the alcohol solution is in the range of 0.05% to 2%. The alcohol may be methanol, ethanol, or C3-C6 alcohols.

[0026] Depending on the alcohol used, R in formula II can be a C1-C6 alkyl group. The term "C1-C6 alkyl group" refers to compounds with methyl, ethyl, propyl, n-butyl, n-pentyl, n-hexyl groups, or their branched structures, for example.

[0027] In one embodiment, the alcohol used is methanol, ethanol, or propanol, where R is CH3, CH3CH2, or CH3CH2CH2, respectively. In one embodiment, the alcohol used is methanol, and R is CH3.

[0028] As mentioned above, the alcohol solution may also contain an acid. Examples of acids include HCl, HBr, H2SO4, H3PO4, HNO3, F3CCO2H, F3CSO3H, H3CSO3H, or p-toluenesulfonic acid.

[0029] In one embodiment, the acid may be added to the alcohol solution in the form of an acid anhydride. However, not all acids are available as acid anhydrides. In some embodiments, an acid may be produced in situ in the alcohol solution by adding an acyl halide to the alcohol solution.

[0030] The term "acyl group" refers to a group containing a C1-C6 linear or branched alkyl chain. Compared to adding an acidic aqueous solution, a faster reaction is possible by generating the acid in solution (in situ) using an acyl halide. This is because the presence of a large amount of water slows down the esterification reaction.

[0031] In one embodiment, the halide is a chloride, and the acid (HCl) is produced by adding acyl chloride to the alcohol solution. In one embodiment, the acyl group is an acetyl group, and the acid is produced by adding acetyl chloride to the alcohol solution.

[0032] In one embodiment of the present invention, the alcohol is methanol, and acetyl chloride is added to produce HCl in solution (in situ). In one embodiment, the halogen is a bromide, and the acid (HBr) is produced by adding acyl bromide to the alcohol solution.

[0033] In one embodiment, the acyl group is an acetyl group, and the acid is produced by adding acetyl bromide to the alcohol solution. In one embodiment of the present invention, the alcohol is methanol, and acetyl bromide is added to produce HBr in solution (in situ).

[0034] The esterification process may be carried out at temperatures ranging from -20°C to 10°C, for example, from -15°C to 5°C, from -14°C to 5°C, from -13°C to 5°C, from -12°C to 5°C, from -11°C to 5°C, from -10°C to 5°C, from -10°C to 4°C, from -10°C to 3°C, from -10°C to 2°C, from -10°C to 1°C, from -10°C to 0°C, from -9°C to 0°C, from -8°C to 0°C, from -7°C to 0°C, from -7°C to -1°C, from -7°C to -2°C, from -7°C to -3°C, from -7°C to -4°C, etc.

[0035] In one embodiment, the reaction is carried out at temperatures of 5°C, 4°C, 3°C, 2°C, 1°C, 0°C, -1°C, -2°C, -3°C, -4°C, -5°C, -6°C, -7°C, -8°C, -9°C, or -10°C.

[0036] The reaction time depends on the applied temperature and may range from 1 to 50 hours, for example, 1 to 45 hours, 2 to 40 hours, 2 to 30 hours, 2 to 24 hours, 3 to 23 hours, 4 to 22 hours, or 5 to 21 hours.

[0037] The esterification step may be carried out with a molar ratio of acetyl chloride to A-40926 ranging from 30:1 to 5:1, for example, from 25:1 to 5:1, 20:1 to 5:1, 25:1 to 10:1, 20:1 to 10:1, etc.

[0038] In one embodiment, the reaction is carried out with a molar ratio of acetyl chloride:A-40926 of 20:1, 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, 12:1, 11:1, or 10:1.

[0039] After the esterification reaction, the resulting intermediate needs to be prepared for the amidation step. In the methods for synthesizing dalbavancin known in the art, the intermediate from the esterification step is prepared for the amidation step by precipitation, separation of the resulting solid, and drying, in order to remove any undesirable solvents. However, this can lead to an increase in the formation of undesirable impurities, particularly the decomposition products mannosyl aglycone (MAG) and demannosyl derivatives (depending on the pH). In addition, the methods known in the art, which involve pH adjustment to precipitate the product, may produce solids that are not suitable for rapid filtration and may require complete drying in a heated vacuum oven to remove all trace amounts of solvent water and solvent alcohol before the subsequent amide coupling.

[0040] [ka]

[0041] The inventors have surprisingly discovered that by precipitating the compound of formula II using an appropriate amount of an organic poor solvent such as tert-butyl methyl ether (TBME) or dimethoxyethane (DME), the resulting precipitate can be used directly in the subsequent amidation reaction without the need for further drying in an oven, such as a vacuum oven, after a filtration step. The inventors have found that using TBME or DME produces a precipitate that is easily filterable. This precipitate is suitable for easier and more time-efficient filtration, thereby eliminating the need for centrifugation. The inventors have found that this method is particularly suitable for use in large-scale synthetic processes because it produces an easily filterable precipitate, and that this process has been successfully used with the starting compound A-40926 on a scale of 500 grams or more. Other prior known methods may produce precipitates that are filterable on a small scale but not filterable or impractical on a large scale.

[0042] In one embodiment of the present invention, precipitation is performed using TBME. The ratio of the alcohol used for esterification to TBME may be approximately 1 to 5.0, for example, 1 to 4.9, 1 to 4.8, 1 to 4.7, 1 to 4.6, 1 to 4.5, 1 to 4.4, 1 to 4.3, 1 to 4.2, 1 to 4.1, 1 to 4.0, 1 to 3.9, 1 to 3.8, 1 to 3.7, 1 to 3.6, 1 to 3.5, 1 to 3.4, 1 to 3.3, 1 to 3.2, 1 to 3.1, 1 to 3.0, 1 to 2.9, 1 to 2.8, 1 to 2.7, 1 to 2.6, 1 to 2.5, 1 to 2.4, 1 to 2.3, 1 to 2.2, 1 to 2.1, 1 to 2.0, etc.

[0043] The solution containing the precipitated compound of formula II may be filtered before step (iv). The solution containing the precipitated compound of formula II may be filtered by gravity alone. Therefore, in this embodiment, the filtration process is carried out without pressurizing or depressurizing the filter.

[0044] The filtration step may be completed by exposing the esterification product to a gas stream on a filter, thereby preparing the product for the subsequent amidation reaction. Examples of the gas used include dry nitrogen gas. This process can be completed quickly, in about an hour, and avoids the formation of decomposition products, unlike drying in a vacuum oven.

[0045] The solution containing the precipitated compound of formula II may be filtered using a Nutsche filter. In one embodiment, filtration is performed under gravity and / or under pressure with dry nitrogen gas upstream of the filter and / or under reduced pressure downstream of the Nutsche filter.

[0046] After filtering the solution containing the precipitated compound of formula II, the precipitate is dissolved in a suitable solvent. Examples of solvents include DMSO (dimethyl sulfoxide), DMF (dimethylformamide), DMA (dimethylacetamide), THF (tetrahydrofuran), NMP (N-methyl-2-pyrrolidone), or mixtures thereof. A standard amine coupling reagent and 3-(dimethylamino)-1-propylamine were added to the resulting solution to obtain the compound of formula III.

[0047] [ka]

[0048] Here, R may be a C1-C6 alkyl group. Examples of amine coupling reagents that can be used include DCC (dicyclohexylcarboiimide), DIC (diisopropylcarbodiimide), EDC (N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide), HOBt (hydroxybenzotriazole), HOAt (1-hydroxy-7-azabenzotriazole), PyBOP (benzotriazole-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate), and HATU (O-(7-azabenzotriazole-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate).

[0049] After the amine coupling step, the compound of formula II may be obtained by precipitation, filtration, and optionally vacuum drying. To obtain dalbavancin, it is necessary to remove the alkyl group added to the N-acylaminoglucuronic acid carboxyl group during the esterification process. This is done by ester hydrolysis.

[0050] The dalbavancin obtained by the synthesis process described herein may be further purified to remove impurities related to residual fermentation and / or impurities related to synthesis and the process.

[0051] All figures in this specification and claims are qualified with the term “approximately,” meaning that each figure includes a small variation defined as ±10% of the number or range in question.

[0052] (Example 1) (a) Under a dry nitrogen atmosphere at 0°C, A40926 (645 g) was gradually added to methanolic hydrochloric acid solution (0.55 M, 10.0 L). The rate was such that the temperature would not exceed 4°C. The temperature was then adjusted to 4°C and the progress of the reaction was monitored at regular intervals using HPLC. Once the reaction was determined to be complete by HPLC, TBME (32.0 L) was added over approximately 1 hour to precipitate the product. The solid material was filtered using a Nutsche filter and washed with additional TBME (3 × 5 L). The filter cake was dried using a stream of dry nitrogen gas until the solid material was consistently powdery. The semi-dried material was used directly in the next reaction.

[0053] (b) The semi-dried material (1 equivalent) was dissolved in DMF (75 mM) and cooled to 0°C. Triethylamine (2.0 equivalents) and HATU (1.0 equivalent) were added. After 10 minutes, 3-(dimethylamino)-1-propylamine (1.0 equivalent) was added and the mixture was stirred for a further 30 minutes. Ethyl acetate was added to precipitate the product, which was filtered and washed with additional ethyl acetate. The solid material was dried in a vacuum oven at 30°C and used in the next reaction without further purification.

[0054] (c) The slurry of the coupling product (667g) and water (12.5L) was cooled to 2°C, and sodium hydroxide aqueous solution (2M, 1.4L) was added over 5 minutes to maintain a temperature below 4°C. The temperature was then adjusted to 6°C, and the reaction mixture was stirred at this temperature for 3 hours.

Claims

1. (i) A step of providing a compound of formula I or a salt thereof, 【Chemistry 1】 (ii) A step of performing an esterification step by adding a methanol solution or ethanol solution containing an acid to the compound of formula I in order to obtain the compound of formula II, 【Chemistry 2】 Here, X is Cl or Br, and R is a methyl group or an ethyl group. (iii) A step of forming a precipitate by adding an appropriate amount of tert-butyl methyl ether or dimethoxyethane, (iv) In order to obtain the compound of formula III, the step of adding 3-(dimethylamino)-1-propylamine to the precipitate, 【Transformation 3】 Here, R is a methyl group or an ethyl group. (v) A step of performing an ester hydrolysis step to obtain dalbavancin or a salt thereof, The synthesis process of dalbavansine, including the process described above.

2. The process according to claim 1, wherein a precipitation step (iii) is performed using tert-butylmethyl ether.

3. The process according to claim 1, wherein the acid in step (ii) is an acid anhydride.

4. The process according to any one of claims 1 to 3, wherein the acid in step (ii) is directly produced in the methanol solution or ethanol solution by adding acyl chloride or acyl bromide to the methanol solution or ethanol solution.

5. The process according to claim 4, wherein the acid is produced by adding acetyl chloride to the methanol solution or the ethanol solution.

6. The process according to claim 4, wherein the acid is produced by adding acetyl bromide to the methanol solution or the ethanol solution.

7. The process according to any one of claims 1 to 6, wherein the methanol solution or ethanol solution in step (ii) is a methanol solution.

8. The process according to any one of claims 1 to 7, wherein R is a methyl group.

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