阅读说明：本技术 一种奥利司他关键中间体的精制方法 (Refining method of orlistat key intermediate ) 是由 夏军 黄治川 邓祥林 李大明 赵伟淑 于 2020-12-18 设计创作，主要内容包括：本发明公开了一种奥利司他关键中间体精制方法及其关键中间体杂质和制备方法。所述精制方法为化合物I在有机溶剂或混合有机溶剂中重结晶除去工艺中难以除去的杂质1～杂质5,该方法对杂质1～杂质5的选择性好,该方法操作简便、成本低、适合工业化生产。本发明还提供了杂质3及其制备方法和作为奥利司他关键中间体(3S,4S)-3-己基-4-〔(R)-2-(羟基十三烷基)〕氧杂环丁-2-酮(化合物I)的杂质对照品中的应用。(The invention discloses a refining method of an orlistat key intermediate, and impurities and a preparation method of the orlistat key intermediate. The refining method is to recrystallize the compound I in an organic solvent or a mixed organic solvent to remove impurities 1-5 which are difficult to remove, the method has good selectivity on the impurities 1-5, the method is simple and convenient to operate, the cost is low, and the method is suitable for industrial production. The invention also provides an impurity 3, a preparation method thereof and application of the impurity 3 as an impurity reference substance of an orlistat key intermediate (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ]) oxetan-2-one (compound I).)

1. A method for refining an orlistat key intermediate (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I) comprises the following steps:

(1) dissolving the crude compound (I) in an organic solvent;

(2) cooling, precipitating solid, and separating to obtain refined product of compound (I).

2. The refining method according to claim 1, wherein the organic solvent in step (1) is one or a mixture of two or more selected from methanol, ethanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, acetone, butanone, diethyl ether, isopropyl ether, methyl tert-butyl ether, ethyl acetate, dichloromethane, acetonitrile, n-pentane, n-hexane, n-heptane, n-octane, and isooctane, preferably one or a mixture of two or more selected from methanol, ethanol, isopropanol, acetone, isopropyl ether, n-hexane, n-heptane, and isooctane.

3. The purification method according to claim 1 to 2, wherein the organic solvent used in step (1) is 0.5 to 15 times, preferably 1 to 7 times, the mass (ml/g) of the compound (I).

4. The refining method of claims 1 to 3, wherein the dissolving temperature in step (1) is from room temperature to the boiling temperature of the system, preferably from 10 ℃ to 100 ℃, more preferably from 20 ℃ to 80 ℃.

5. The refining method of claim 1 to 4, wherein the cooling temperature in step (2) is 0 ℃ to 60 ℃ lower than the dissolving temperature, and when the dissolving temperature is room temperature, the cooling temperature is room temperature.

6. The purification method according to claim 1 to 5, wherein the purified product of the (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I) has a purity of 90.0% or more.

7. An impurity 3 having the following structure:

wherein TBS is tert-butyldimethylsilyl.

8. A process for producing the impurity 3 according to claim 7, comprising the steps of: (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I) is reacted with t-butyldimethylsilyl chloride in the presence of a basic substance and a solvent to obtain an impurity 3.

9. The production method according to claim 8, wherein the basic substance is one or more compounds selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, triethylamine, imidazole, and N, N-diisopropylethylamine, preferably imidazole;

and/or the reaction solvent is one or a mixture of more than two of tetrahydrofuran, N-dimethylformamide, 1, 4-dioxane, N-dimethylacetamide, methanol and ethanol, preferably N, N-dimethylformamide, N-dimethylacetamide or a mixture of the N, N-dimethylformamide and the N, N-dimethylacetamide;

and/or the reaction temperature of the coupling reaction is-20 ℃ to 100 ℃, preferably 10 ℃ to 50 ℃, and more preferably 20 ℃ to 40 ℃.

10. Use of impurity 3 according to claim 7 as an impurity control for (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I).

Technical Field

The invention relates to the technical field of drug synthesis, in particular to a refining method of an orlistat key intermediate, key intermediate impurities and a preparation method thereof.

Background

Orlistat was developed by rots, switzerland, a non-systemically acting, long-acting and potent specific gastric and pancreatic lipase inhibitor for the treatment of obesity. Has the advantages of less systemic absorption, no accumulation after repeated use, low blood concentration, no tolerance and the like, and the adverse reaction is mainly gastrointestinal reaction. The chemical name is as follows: (S) -2-formylamino-4-methyl-pentanoic acid- (S) -1- { [ (2S, 3S) -3-hexyl-4-oxo-2-oxetanyl ] methyl } dodecyl ester, whose structural formula is as follows:

at present, various synthetic routes of orlistat are involved, wherein the involved routes are (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ]) oxetan-2-one compound (I) and N-formyl-L-leucine, and the orlistat is obtained by Mitsunobu reaction and crystallization under the action of triphenylphosphine and diisopropyl azodicarboxylate. Patent WO2009059046a1 discloses preparation of ketonic acid ester from ethyl acetoacetate as starting material, followed by reduction with chiral catalyst to obtain R-alkanoate, protection with t-butyldimethylsilyl chloride to obtain R-t-butyldimethylsilyloxy-alkanoate, reduction with DIBAL-H to obtain alkanal (II), and reaction with t-butyldimethylsilyloxy-1- (2-pyridylmercapto) trans-octene (III) prepared from n-octanoic acid as starting material to obtain orlistat key intermediate (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I), wherein the synthetic route is as follows:

the inventor finds that the compound (I) is synthesized according to the method, two reaction operations of condensation and deprotection are needed in the last step to obtain the compound (I), the HPLC purity of the product is lower than 80%, a large amount of impurities are generated in the process, the separation and purification difficulty is very high, the impurities are difficult to remove through refining and purification, and the quality of the product is greatly influenced; meanwhile, patent WO2009059046a1 describes that column chromatography purification can be used to remove a plurality of impurities, and is not suitable for industrial production due to relatively low yield and high solid waste pressure.

Disclosure of Invention

The present inventors provide a purification method for preparing orlistat key intermediate (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I). The method is characterized in that the impurities 1-5 which are difficult to remove in the process of recrystallizing the compound (I) in an organic solvent or a mixed organic solvent are removed, the method has good selectivity on the impurities 1-5, the method is simple and convenient to operate, low in cost and suitable for industrial production.

In the present invention, the chemical structures of the impurity 1, the impurity 2, the impurity 3, the impurity 4 and the impurity 5 are as follows:

wherein TBS in the chemical structure of the impurity 3 is tert-butyldimethylsilyl.

The invention provides a refining method of an orlistat key intermediate (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I), which comprises the following steps:

(1) dissolving the crude compound (I) in an organic solvent;

(2) cooling, precipitating solid, and separating to obtain refined product of compound (I).

In an embodiment of the present invention, in the above refining method step (1), the organic solvent is one or a mixture of two or more selected from methanol, ethanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, acetone, butanone, diethyl ether, isopropyl ether, methyl tert-butyl ether, ethyl acetate, dichloromethane, acetonitrile, n-pentane, n-hexane, n-heptane, n-octane, and isooctane; preferably, the solvent is one or a mixture of two or more selected from methanol, ethanol, isopropanol, acetone, isopropyl ether, n-hexane, n-heptane and isooctane.

In an embodiment of the present invention, in the step (1) of the above purification method, the volume usage of the organic solvent is 0.5 to 15 times, preferably 1 to 7 times of the mass (ml/g) of the compound (I).

In an embodiment of the present invention, in the step (1) of the above refining method, the dissolving temperature is from room temperature to the boiling temperature of the crude compound (I) -organic solvent system, preferably, from 10 ℃ to 100 ℃, more preferably, from 20 ℃ to 80 ℃.

In an embodiment of the present invention, in the step (2) of the refining method, the cooling temperature is 0 to 60 ℃ lower than the dissolving temperature; in one embodiment, when the temperature of dissolution is room temperature, the temperature of cooling is also room temperature, thereby precipitating a solid.

In an embodiment of the present invention, in the step (3) of the above refining method, the separation may be performed by filtration or centrifugation; optionally, further comprising rinsing the isolated solid with the organic solvent.

In an embodiment of the present invention, the crude compound (I) can be obtained by the following synthesis method of condensation and deprotection:

for example, the product obtained by the process of preparation of WO2009059046A 1.

In the above embodiment, the purity of the purified product of the compound (I) obtained by the above purification method is 90.0% or more.

In one embodiment of the present invention, the refining process provided by the present invention is: adding the crude product of the compound (I) into an organic solvent, stirring, heating to 20-80 ℃, and dissolving; and cooling the obtained system to-10-30 ℃, filtering, and drying the obtained filter cake at 35 ℃ under reduced pressure to obtain a high-purity refined product of the compound (I).

In another aspect, the present invention provides an impurity 3:

wherein TBS is tert-butyldimethylsilyl.

In a third aspect, the present invention provides a method for producing the above-mentioned impurity 3, comprising the steps of: the compound (I) and tert-butyldimethylsilyl chloride are subjected to a coupling reaction in the presence of an alkaline substance and a reaction solvent to obtain an impurity 3.

In the method for preparing the impurity 3, the basic substance is one or more compounds selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, triethylamine, imidazole and N, N-diisopropylethylamine, and imidazole is preferred.

In the method for preparing the impurity 3, the reaction solvent is one or a mixture of two or more selected from tetrahydrofuran, N-dimethylformamide, 1, 4-dioxane, N-dimethylacetamide, methanol and ethanol, and preferably is N, N-dimethylformamide, N-dimethylacetamide or a mixture thereof.

In the method for preparing the impurity 3, the reaction temperature of the coupling reaction is-20 ℃ to 100 ℃, preferably 10 ℃ to 50 ℃, and more preferably 20 ℃ to 40 ℃.

In a fourth aspect, the present invention provides impurity 3 for use as a control for controlling the quality of compound (I).

The inventor finds that impurities 1-5 cannot be completely removed in the general crystallization process of the compound (I). However, with the purification method of the present invention, the content of these impurities is significantly reduced, and the quality of the compound (I) can be improved.

The invention has the following beneficial effects:

1. the (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I) crystal has limited effect of removing impurities 1-5, the purification difficulty is high, the solvent system has high selectivity for removing the impurities 1-5, and is beneficial to obtaining a high-purity final product in a later period, and the inventor tries to remove the impurities in other solvent systems and cannot selectively remove the impurities 1-5.

2. The method is simple in operation, and the technology can be used for preparing the compound (I) in large quantity, has the purity of over 90.0 percent and can be used for commercial production.

Drawings

FIG. 1 shows the mass spectrum of impurity 3;

fig. 2 shows a hydrogen spectrum of impurity 3.

Detailed Description

The following examples further illustrate the invention, but the scope of the invention is not limited thereto.

Comparative example 1 crude preparation example 13 of compound (I) in reference patent WO2009059046a 1:

under the protection of nitrogen, 156.0g of dry and dehydrated anhydrous zinc chloride is added into a reaction bottle, then a mixed solution of 155.6g of a compound (II) and 1000ml of dichloromethane and a mixed solution of 263g of a compound (III) and 500ml of dichloromethane are sequentially added, stirring reaction is carried out for 60 hours at room temperature after the addition is finished, a phosphate buffer solution with the pH value of 7 is added after the reaction is finished, stirring and quenching reaction is carried out for 30 minutes, filtering is carried out (a proper amount of diatomite is added), an organic layer is dried by anhydrous sodium sulfate, filtering is carried out, the filtrate is concentrated under reduced pressure, the residue is subjected to column chromatography silica gel column chromatography purification (eluent: n-heptane: ethyl acetate: 10:1), target eluent is collected, and 150.0g of target oily matter is obtained after the eluent is concentrated, so that the yield is obtained: 42.7 percent.

Adding 140.0g of the target oily substance and 1400ml of acetonitrile into a reaction bottle, dropwise adding 565.0g of 55% hydrofluoric acid solution at 0-10 ℃, keeping the temperature for 2 hours after dropwise adding, heating to room temperature for reaction for 5 hours, adding a petroleum ether extraction product after the reaction is finished, adjusting the pH of the system by using sodium bicarbonate, washing an organic layer by using saturated sodium chloride, drying the organic layer by using anhydrous sodium sulfate, filtering, concentrating the filtrate at 40 ℃ under reduced pressure, separating the obtained residue by using silica gel column chromatography to obtain a product (a developing agent: n-hexane: ethyl acetate: 10:1), separating the obtained residue to obtain 55.2g of a white solid, namely the target product compound (I), wherein the purity is 27.8%, and the yield is as follows: 52.1 percent. The overall yield of the two steps was 22.2%.

Example 1

Adding 5.0g of the crude product of the compound (I) (the target product compound (I) obtained in the comparative example 1) into a 50ml reaction bottle, adding 25ml of isopropyl ether, heating to 40-50 ℃, stirring for dissolving, cooling to 20-30 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 3.5g of an off-white solid with the purity: 96.66%, yield: 70 percent.

Example 2

Adding 5.0g of the crude product of the compound (I) (the target product compound (I) obtained in the comparative example 1) into a 50ml reaction bottle, adding 30ml of n-heptane, heating to 50-60 ℃, stirring for dissolving, cooling to 10-20 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 4.4g of an off-white solid with the purity: 98.32%, yield: 87 percent.

Example 3

Adding 5.0g of crude compound (I) (the target product compound (I) obtained in comparative example 1) into a 50ml reaction bottle, adding 5ml of isopropanol and 35ml of isopropyl ether, heating to 40-50 ℃, stirring for dissolving, cooling to 10-20 ℃ after dissolving, stirring for crystallizing for 3 hours, filtering, and drying a filter cake at 35 ℃ to obtain 2.7g of off-white solid with purity: 92.0%, yield: 53 percent.

Example 4

Adding 5.0g of crude compound (I) (the target product compound (I) obtained in comparative example 1) into a 50ml reaction bottle, adding 4ml of methanol and 30ml of n-heptane, heating to 40-50 ℃, stirring for dissolving, cooling to 0-10 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 3.0g of white solid with purity: 98.83%, yield: 60 percent.

Example 5

Adding 9.0g of crude compound (I) (the target product compound (I) obtained in comparative example 1) into a 100ml reaction bottle, adding 8ml of methanol and 60ml of n-heptane, heating to 45-55 ℃, stirring for dissolving, cooling to 0-10 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 5.6g of white solid with purity: 99.17%, yield: 62.2 percent.

Example 6

Adding 5.0g of crude compound (I) (the target product compound (I) obtained in comparative example 1) into a 100ml reaction bottle, adding 4ml of acetone, 40ml of n-hexane and 3ml of isopropyl ether, heating to 40-45 ℃, stirring for dissolving, cooling to 0-10 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 2.6g of an off-white solid with the purity: 97.39%, yield: 52 percent.

Example 7

Adding 5.0g of the crude product of the compound (I) (the target product compound (I) obtained in the comparative example 1) into a 50ml reaction bottle, adding 30ml of n-hexane, heating to 50-60 ℃, stirring for dissolving, cooling to 10-20 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 3.9g of white solid with the purity: 96.66%, yield: 78 percent.

Example 8

Adding 5.0g of the crude product of the compound (I) (the target product compound (I) obtained in the comparative example 1) into a 50ml reaction bottle, adding 30ml of isooctane, heating to 50-60 ℃, stirring for dissolving, cooling to 20-30 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 3.7g of white solid with the purity: 91.93%, yield: 74 percent.

Example 9

Adding 5.0g of the crude product of the compound (I) (the target product compound (I) obtained in the comparative example 1) into a 50ml reaction bottle, adding 35ml of n-hexane and 4ml of methanol, heating to 40-50 ℃, stirring for dissolving, cooling to-5-0 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 2.9g of white solid with purity: 99.0%, yield: 58 percent.

Example 10

Adding 5.0g of crude compound (I) (the target product compound (I) obtained in comparative example 1) into a 50ml reaction bottle, adding 15ml of ethanol, heating to 40-50 ℃, stirring for dissolving, cooling to-10-5 ℃ after dissolving, stirring for crystallizing for 2 hours, filtering, and drying a filter cake at 35 ℃ to obtain 2.4g of white solid with purity: 99.47%, yield: 48 percent.

Comparative example 1 the purity and yield of crude compound (I) and refined compound (I) of examples 1-10 above, and the contents of impurity 1, impurity 2, impurity 3, impurity 4, and impurity 5 are shown in the table:

example 11 preparation of impurity 3

A100 ml reaction flask was charged with 10.00g of (3S,4S) -3-hexyl-4- [ (R) -2- (hydroxytridecyl) ] oxetan-2-one compound (I), 5.10g of t-butyldimethylsilyl chloride, 3.84g of imidazole and 30ml of N, N-dimethylformamide, and the mixture was dissolved by stirring, reacted at 20 to 30 ℃ at room temperature, 100ml of water and 100ml of ethyl acetate were added thereto to separate the solution. The organic phase was washed with 30ml of water and dried over anhydrous sodium sulfate. Filtering, and evaporating the filtrate at 40 deg.C under reduced pressure to obtain colorless oily substance 13.10 g. Weighing 3.10g of oily substance, purifying by column (eluent PE: EA is 100:1), collecting eluent of the product, and evaporating to dryness at 40 ℃ under reduced pressure to obtain 2.20g of colorless oily substance with the purity of 90.83%. MS (ESI)⁺): m/z＝491.38736[M+Na]⁺；¹H-NMR(600MHz,CDCl₃):δ4.44～4.41(m，1H)、 3.85～3.81(m，1H)、3.19～3.16(m，1H)、1.87～1.80(m，3H)、1.79～1.69(m， 1H)、1.50～1.43(m，4H)、1.38～1.28(m，24H)、0.89～0.85(s，15H)、0.07～0.01 (s，6H)ppm.

Mass Spectrometry (MS) detector apparatus described above: bruker SolariX fourier transform ion cyclotron resonance mass spectrometer, ion source: ESI⁺(ii) a Nuclear magnetic resonance hydrogen spectrum (¹H NMR) instrumentation: agilent 600DD2(600MHz) high resolution nuclear magnetic resonance spectrometer, solvent: CDCl₃(ii) a Internal standard: TMS; temperature: 25 ℃;

the detection conditions for HPLC were as follows:

a chromatographic column: agilent ZORBAX Eclipse XDB-C18, 250X 4.6mm, 5.0 μm, flow rate: 1.0ml/min, detection wavelength: 210nm, 200nm, column temperature: 35 ℃, sample introduction: 20 μ l.

Mobile phase A: acetonitrile; mobile phase B: 0.1% aqueous phosphoric acid, gradient elution according to the following table:

time (minutes)	A(％)	B(％)
			0	50	50
10	90	10
			20	95	5
38	95	5
			39	50	50
45	50	50

Finally, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that, while the invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.