Resolution method and intermediate of phenylalanine derivative

Abstract

The invention provides a resolution method and an intermediate of a phenylalanine derivative as shown in a formula (I). The method comprises a resolution step: a resolution intermediate is obtained by using a resolution reagent to react with a phenylalanine derivative as shown in a formula (I) in a reaction solvent, and the resolution reagent is selected from N-acetyl-D-phenylalanine and / or (2R, 3R)-(-)-diphenylformyl-L-tartaric acid; the reaction solvent is selected from a 90-99% ethanol water solution, absolute ethyl alcohol or acetone. The chiral reagent is used for salifying resolution of the racemate, and the method has the advantages that the operation is simple and convenient, special production equipment is not needed, and the production scale is easy to enlarge. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of medicine, and in particular to a separation method and intermediates of phenylalanine derivatives. Background Art

[0002] Boron neutron capture therapy (BNCT) is an effective method for treating tumors. In BNCT, BPA (Chinese name: 4-dihydroxyborylphenylalanine or 4-boron-L-phenylalanine) is often used as a drug to treat patients. BPA is transported through the neutral amino acid transporter, namely the L-amino acid transport system (LAT-1), so only L-type (s-type) BPA can be used for BNCT treatment.

[0003] In order to monitor the distribution of BPA in the patient's body, a radioactive 18F atom is used to replace a hydrogen atom on the benzene ring in the L-BPA molecule to form F-BPA with 18F. In the synthesis of 18F-BPA, it is necessary to use F-BPA precursors produced in accordance with the requirements of Good Manufacturing Practice (GMP) for pharmaceutical production. Phenylalanine derivatives (such as but not limited to (2S)-2-amino-3-(2,4-dibromophenyl) propionic acid tert-butyl ester) are key intermediates required for the production of 18F-BPA precursors. This intermediate compound can also be used as a synthetic intermediate for boron compounds such as BPA, 2-fluoro-4-boric acid-L-phenylalanine and 2,4-diboric acid-L-phenylalanine that can be used for BNCT treatment, and has very wide application potential.

[0004] In the prior art, the SFC separation technology is often used to split the racemate when producing the above-mentioned synthetic intermediates. This technology has the problems of high equipment cost, small production scale, poor GMP compliance, etc. In addition, since this product has a tert-butyl ester structure, the success rate of selective asymmetric decomposition of this structure using enzymes is extremely low. Therefore, it is necessary to develop a method for chemical splitting of phenylalanine derivatives with stable process, simple operation and easy scalability. Summary of the invention

[0005] One object of the present invention is to provide a method for chiral separation of phenylalanine derivatives;

[0006] Another object of the present invention is to provide an intermediate obtained by the chiral separation method.

[0007] To achieve the above object, on the one hand, the present invention provides a method for chiral separation of phenylalanine derivatives represented by formula (I),

[0008]

[0009] X is selected from Br, I, F, Cl, CN, SCN or OCN;

[0010] R 1 , R 2 Each independently selected from: hydrogen or tert-butyloxycarbonyl;

[0011] R 3 Selected from tert-butyl;

[0012] n = 1 or 2;

[0013] The method comprises a splitting step: comprising using a splitting agent to react with a phenylalanine derivative shown in formula (I) in a reaction solvent to obtain a splitting intermediate. The splitting agent is selected from N-acetyl-D-phenylalanine and / or (2R, 3R)-(-)-diphenylformyl-L-tartaric acid. The reaction solvent is selected from 90-99% ethanol aqueous solution, anhydrous ethanol or acetone.

[0014] Furthermore, the 90-99% ethanol aqueous solution can be selected from 90% ethanol aqueous solution, 92% ethanol aqueous solution, 94% ethanol aqueous solution, 95% ethanol aqueous solution, 96% ethanol aqueous solution, 98% ethanol aqueous solution or 99% ethanol aqueous solution.

[0015] In the present invention, the phenylalanine derivatives represented by formula (I) are racemates. The method of the present invention can effectively perform chiral resolution on the racemates of phenylalanine derivatives to obtain phenylalanine derivatives containing a single configuration with high optical purity.

[0016] According to some specific embodiments of the present invention, the splitting step of the method comprises: using a splitting agent to react with the phenylalanine derivative shown in formula (I) in a reaction solvent, crystallizing the reaction system at 10-30° C., and then filtering to obtain a split intermediate. At this time, the product obtained after precipitation and filtration mainly contains phenylalanine derivative salts of S configuration. Recrystallization can further effectively remove the phenylalanine derivative salts of R configuration in the split intermediate.

[0017] According to some specific embodiments of the present invention, the method comprises stirring the reaction system at 10-30° C. for 10-25 h to crystallize, and then filtering to obtain the resolved intermediate.

[0018] According to some specific embodiments of the present invention, the ee value of the compound represented by formula (II) in the split intermediate is greater than 35%.

[0019]

[0020] A is a resolving agent.

[0021] According to some specific embodiments of the present invention, the compound represented by formula (II) is selected from the compounds represented by the following formula (II-1) or formula (II-2):

[0022]

[0023] According to some specific embodiments of the present invention, the ee value of the compound shown in formula (II) in the split intermediate is 36%-98%. For example, the ee value of the compound shown in formula (II) in the split intermediate can be 36%, 38%, 40%, 45%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97% or 98%.

[0024] The compound represented by formula (II) is a phenylalanine derivative salt of S configuration (ie, a salt obtained by reacting the phenylalanine derivative of formula (I) with a resolution agent).

[0025] According to some specific embodiments of the present invention, the reaction of the resolution agent with the phenylalanine derivative shown in formula (I) comprises reacting the resolution agent with the phenylalanine derivative shown in formula (I) at 30° C. to 55° C. to obtain a resolution intermediate.

[0026] According to some specific embodiments of the present invention, the reaction of the resolution agent with the phenylalanine derivative shown in formula (I) comprises reacting the resolution agent with the phenylalanine derivative shown in formula (I) at 30°C to 55°C for 2-5h to obtain a resolution intermediate.

[0027] In the present invention, the resolution intermediate is a salt formed by a phenylalanine derivative shown in formula (I) and a resolution agent. Phenylalanine derivatives contain an ammonia basic group and are easily reacted with an acidic chiral resolution agent to form a salt of the phenylalanine derivative. The resolution intermediate can remove the chiral resolution agent by hydrolysis.

[0028] According to some specific embodiments of the present invention, the resolution intermediate includes a phenylalanine derivative salt. Further, the resolution intermediate prepared by the method of the present invention includes a phenylalanine derivative salt of S configuration with high optical purity.

[0029] According to some specific embodiments of the present invention, the reaction of the resolving agent with the phenylalanine derivative shown in formula (I) comprises reacting the resolving agent with the phenylalanine derivative shown in formula (I) in a reaction solvent; the reaction solvent is 90-99% ethanol aqueous solution, and the resolving agent is N-acetyl-D-phenylalanine.

[0030] According to some specific embodiments of the present invention, the reaction of the resolving agent with the phenylalanine derivative shown in formula (I) comprises reacting the resolving agent with the phenylalanine derivative shown in formula (I) in a reaction solvent; the reaction solvent is acetone, and the resolving agent is (2R, 3R)-(-)-diphenylformyl-L-tartaric acid.

[0031] According to some specific embodiments of the present invention, the molar ratio of the phenylalanine derivatives represented by formula (I) to the resolution agent is 1:0.4-1.0. Further, the molar ratio of the phenylalanine derivatives represented by formula (I) to the resolution agent is 1:0.5-0.8.

[0032] According to some specific embodiments of the present invention, the molar ratio of the phenylalanine derivative represented by formula (I) to the resolution agent is 1:0.6.

[0033] According to some specific embodiments of the present invention, the volume (mL) of the reaction solvent is 10 to 35 times the mass (g) of the phenylalanine derivative shown in formula (I). For example, the volume (mL) of the reaction solvent can be 10 times, 12 times, 15 times, 18 times, 20 times, 22 times, 25 times, 30 times, 32 times or 35 times the mass (g) of the phenylalanine derivative shown in formula (I). In other words, the volume mass ratio (mL / g) of the reaction solvent to the phenylalanine derivative shown in formula (I) is 10 to 35.

[0034] According to some specific embodiments of the present invention, the mass of the phenylalanine derivative shown in formula (I) put into the splitting step is 30mg to 50g. For example, the mass of the phenylalanine derivative can be 30mg, 50mg, 100mg, 200mg, 300mg, 500mg, 1g, 2g, 5g, 10g, 20g, 40g or 50g. The splitting method of the present invention can be applicable to large-scale production.

[0035] According to some specific embodiments of the present invention, the method further comprises: subjecting the product (split intermediate) obtained in the splitting step to at least one recrystallization step in a recrystallization solvent to obtain a recrystallized split intermediate. In the present invention, after the recrystallization treatment, the optical purity of the S-configuration phenylalanine derivative salt can be further improved.

[0036] According to some specific embodiments of the present invention, the recrystallization comprises stirring the product obtained in the resolution step in a recrystallization solvent at 45-55°C for 1.5-2.5 hours, and then stirring at 15-25°C for 14-20 hours to obtain a recrystallized resolution intermediate.

[0037] According to some specific embodiments of the present invention, in the recrystallized resolution intermediate, the HPLC content of the S-configuration phenylalanine derivative salt (the salt formed by the phenylalanine derivative and the resolution agent) is not less than 99%.

[0038] According to some specific embodiments of the present invention, the recrystallization comprises mixing the resolved intermediate with a recrystallization solvent to obtain a suspension, heating the suspension to 45-55°C within 20-40 minutes, stirring for 1.5-2.5 hours, then cooling to 15-25°C at a rate of 4-6°C / h, stirring for 14-20 hours, to obtain a recrystallized resolved intermediate.

[0039] According to some specific embodiments of the present invention, the recrystallization solvent is selected from at least one of anhydrous ethanol, tetrahydrofuran, acetonitrile, acetone and 90-99% ethanol aqueous solution.

[0040] According to some specific embodiments of the present invention, wherein, the volume (mL) of the recrystallization solvent is 9 to 15 times the mass (g) of the resolution intermediate. Further, the volume (mL) of the recrystallization solvent can be 9 times, 10 times, 11 times, 12 times, 13 times, 14 times or 15 times the mass (g) of the resolution intermediate. In other words, the volume mass ratio (mL / g) of the recrystallization solvent to the resolution intermediate is 9 to 15.

[0041] According to some specific embodiments of the present invention, the recrystallization further comprises filtering the precipitated crystals after the stirring is completed to obtain a filter cake.

[0042] Further, the filter cake obtained after recrystallization is dried under vacuum at 50±5° C. to obtain a product. At this time, the optical purity of the S-configuration phenylalanine derivative salt in the product is not less than 99%.

[0043] According to some specific embodiments of the present invention, the method further comprises the step of hydrolyzing the resolution intermediate obtained in the step of reacting with the resolution agent or the resolution intermediate that has been recrystallized.

[0044] According to some specific embodiments of the present invention, the phenylalanine derivative of formula (III) obtained by hydrolysis

[0045] In formula (III), X is independently selected from Br, I, F, Cl, CN, SCN or OCN; R 1 , R 2 Each is independently selected from: hydrogen or tert-butyloxycarbonyl; R 3 Selected from tert-butyl; n=1 or 2.

[0046] In the present invention, the phenylalanine derivative of formula (III) is an S-configuration phenylalanine derivative.

[0047] According to some specific embodiments of the present invention, the phenylalanine derivative obtained by hydrolysis is selected from the following structures:

[0048]

[0049] In formula (IIIa) and formula (IIIb), X is independently selected from Br, I, F, Cl, CN, SCN or OCN; R 1 , R 2 Each is independently selected from: hydrogen or tert-butyloxycarbonyl; R 3 Selected from tert-butyl.

[0050] The hydrolysis can be carried out according to conventional hydrolysis in the art. According to some specific embodiments of the present invention, the method comprises hydrolyzing the split intermediate obtained in the split reaction step or the recrystallized split intermediate under alkaline conditions.

[0051] According to some specific embodiments of the present invention, the pH value of the alkaline condition is 7-14.

[0052] According to some specific embodiments of the present invention, the alkaline condition is in the presence of a base. Further, the base is selected from but not limited to at least one of metal hydroxides, metal carbonates, metal bicarbonates, and ammonia water.

[0053] According to some specific embodiments of the present invention, the base is selected from a mixture of one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and aqueous ammonia.

[0054] According to some specific embodiments of the present invention, the reaction temperature of the hydrolysis is 0-100°C; preferably 10-80°C; more preferably 15-60°C; most preferably 20-40°C.

[0055] According to some specific embodiments of the present invention, the reaction time of the hydrolysis is 5 min-2 h; preferably 10 min-1.5 h; more preferably 20 min-1 h.

[0056] According to some specific embodiments of the present invention, the reaction solvent for the hydrolysis is selected from a mixture of one or more of 95% ethanol aqueous solution, anhydrous ethanol, water or acetone.

[0057] According to some specific embodiments of the present invention, the phenylalanine derivative is selected from the following structures:

[0058]

[0059] X is independently selected from Br, I, F, Cl, CN, SCN or OCN;

[0060] R 1 , R 2 Each independently selected from: hydrogen or tert-butyloxycarbonyl;

[0061] R 3 Selected from tert-butyl.

[0062] According to some specific embodiments of the present invention, X is independently selected from Br, I, F, and Cl.

[0063] According to some specific embodiments of the present invention, the phenylalanine derivative is selected from but not limited to one of the following structures:

[0065]

[0066]

[0067] The present invention takes tert-butyl 2-amino-3-(2,4-dibromophenyl) propionate as an example, and the separation method thereof is described in detail as follows:

[0068]

[0069] Add appropriate amount of tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate and 10-30V reaction solvent to a reaction container in sequence to dissolve, then add a resolution agent to obtain a suspension, stir at 30°C-55°C for 2-5h, cool to 20°C, keep for 10-20h to precipitate crystals, and filter to obtain a crude product; place the crude product in a reaction container, add 12±2V acetone at room temperature to obtain a suspension; heat to 50±5°C within half an hour, keep stirring at the temperature for 2±0.5 hours; cool to 20±5°C at 5±1°C / h, keep stirring for about 17±3h, precipitate crystals, i.e., the product after recrystallization, remove some impurities, and then filter at room temperature; dry the filter cake in vacuum at 50±5°C to obtain (2s)-tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate chiral acid salt. The obtained chiral acid salt can be neutralized with a base until the pH value of the reaction solution reaches 7 to 14, and (2S)-2-amino-3-(2,4-dibromophenyl)propionic acid tert-butyl ester is freed and filtered out. (2S)-2-amino-3-(2,4-dibromophenyl)propionic acid tert-butyl ester:

[0070] The tert-butyl 2-amino-3-(2,4-dibromophenyl) propionate is prepared by the following method:

[0071] 1. Synthesis of tert-butyl 2-amino-3-(2,4-dibromophenyl) propionate

[0072] Dissolve N-dibenzylidene-glycine tert-butyl ester (40g, 135.42mmol, 1eq), 1,4-dibromobenzyl bromide (44.53g, 135.42mmol, 1eq), and tetrabutylammonium bromide (436.55mg, 1.35mmol, 0.01eq) in 300mL toluene, and add 80mL potassium hydroxide (100g, 1.78mol, 13.16eq) aqueous solution. Stir at 25°C for 12 hours until the reaction is complete. Let stand to separate, discard the aqueous phase, and retain the organic phase. Concentrate the organic phase at 55-60°C until no distillation occurs. Add acetonitrile (6v) and heat to 50-55°C to dissolve. Slowly cool to 0-5°C in a gradient (10-15°C per hour) to crystallize. The mixture was stirred at 0-5°C for 1-2 hours, filtered, and the filter cake was rinsed with 0-5°C acetonitrile (1v), the mother liquor was discarded, and the filter cake was dried in a 45-50°C forced air drying oven to obtain N-dibenzhydryl-2,4-dibromophenylalanine tert-butyl ester.

[0073] Add N-dibenzylidene-2,4-dibromophenylalanine tert-butyl ester and tetrahydrofuran (3v) into a 50.00ml four-necked bottle. Add a mixed solution of citric acid (4.00eq.) and water (3v) dropwise. Stir for 20h, and concentrate the reaction solution at 45-55°C until no distillation occurs. Add ethyl acrylate (5v) and water (5v) and stir for 0.5h, separate the layers, and retain the aqueous phase. Extract the organic phase twice with water (3.5v), combine the aqueous phases and extract the aqueous phase twice with EA (1.5v), add EA (5v) to the aqueous phase and stir, and adjust the pH to 8-9 with sodium carbonate. The organic phase was washed once with saturated sodium chloride solution (5v), and the organic phase was concentrated at 45-55°C until no distillation occurred to obtain tert-butyl 2-amino-3-(2,4-dibromophenyl)propanoate as an oil (51.87 g, purity: 98.0%, yield 70.5%).

[0074] On the other hand, the present invention also provides an intermediate represented by formula (II),

[0075]

[0076] wherein X is selected from Br, I, F, Cl, CN, SCN or OCN;

[0077] R 1 , R 2 Each independently selected from: hydrogen or tert-butyloxycarbonyl;

[0078] R 3 Selected from tert-butyl;

[0079] n = 1 or 2;

[0080] A is a resolving agent.

[0081] Further, A is independently selected from N-acetyl-D-phenylalanine or (2R,3R)-(-)-diphenylformyl-L-tartaric acid.

[0082] According to some specific embodiments of the present invention, the compound represented by formula (II) is selected from the compounds represented by the following formula (II-1) or formula (II-2):

[0083]

[0084]

[0085] According to some specific embodiments of the present invention, the intermediate comprises one of the following structures:

[0086]

[0087] According to some specific embodiments of the present invention, X is independently selected from Br, I, F, and Cl.

[0088] The intermediate represented by formula (II) can be prepared by the chiral resolution method of the present invention.

[0089] The phenylalanine derivatives of formula (III) can be prepared by the chiral resolution method of the present invention.

[0090] The intermediate represented by formula (II) can be used to prepare the phenylalanine derivatives represented by formula (III) of the present invention.

[0091] The intermediate represented by formula (II) and / or the phenylalanine derivative represented by formula (III) of the present invention can be used as a synthetic intermediate for preparing boron compounds such as 4-boron-L-phenylalanine (BPA), 2-fluoro-4-boric acid-L-phenylalanine (F-BPA) and 2,4-diboric acid-L-phenylalanine that can be used for BNCT treatment, and has very wide application potential.

[0092] In summary, the present invention provides a method for resolving phenylalanine derivatives and intermediates thereof. The technical solution of the present invention has the following advantages:

[0093] The present invention uses a chiral reagent to perform salt formation and separation of racemates, which has the advantages of simple operation, no need for special production equipment, and easy expansion of production scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 is the chromatogram of structure identification example 1;

[0095] Figure 2 This is the chromatogram of structure identification example 2. DETAILED DESCRIPTION

[0096] The implementation process of the present invention and the beneficial effects produced are described in detail below through specific embodiments, which is intended to help readers better understand the essence and characteristics of the present invention, and is not intended to limit the scope of implementation of the present invention.

[0097] The chromatographic conditions for the ee value test in the embodiment of the present invention are as follows: chromatographic column: DAICEL CHIRALPAK ZWIX (250 mm*4 mm, 3 um); mobile phase [water (50 mM formic acid + 25 mM diethylamine): methanol: tetrahydrofuran = 2:38:60)]; flow rate: 0.5 ml / min; detection wavelength: 210 nm; column temperature: 40°C.

[0098] Example 1

[0099] Add 30 mg of tert-butyl 2-amino-3-(2,4-dibromophenyl) propionate to the reaction container in sequence, add anhydrous ethanol (16v, the volume of anhydrous ethanol is 16 times the mass of tert-butyl 2-amino-3-(2,4-dibromophenyl) propionate) and stir to dissolve; add N-acetyl-D-phenylalanine (0.6eq), stir at 40°C for 5h, after the reaction is completed, cool to 10°C to precipitate crystals, filter and vacuum dry, the ee value of the tested sample is 36.8%.

[0100] Embodiment 2:

[0101] The difference between this embodiment and embodiment 1 is that embodiment 1 uses anhydrous ethanol as the solvent, while this embodiment uses acetone as the solvent, and the ee value of the obtained sample is 48.2%.

[0102] Embodiment 3:

[0103] The difference between this example and Example 1 is that Example 1 uses anhydrous ethanol (16v) as a solvent, while this example uses a 95% ethanol aqueous solution (20v) as a solvent, and the ee value of the obtained sample is 86.2%.

[0104] Embodiment 4:

[0105] Recrystallization: Take the sample of Example 3 and place it in a reaction container; add 95% ethanol aqueous solution (10v) at room temperature to obtain a suspension; raise the temperature to 50°C within half an hour, maintain stirring at 50°C for two hours; cool to 20°C at 5°C / h, keep stirring overnight; filter at room temperature, and vacuum dry the filter cake at 50°C. The ee value of the test sample is: 94.6%.

[0106] The recrystallized product was subjected to a hydrolysis reaction at a pH of 10-11, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0107] Embodiment 5:

[0108] The difference between this example and Example 4 is that Example 4 uses 95% ethanol aqueous solution (10v) as the recrystallization solvent, while this example uses acetone (10v) as the recrystallization solvent, and the ee value of the obtained sample is 93.6%.

[0109] The recrystallized product is subjected to a hydrolysis reaction at a pH of 7-8, and is liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0110] Embodiment 6:

[0111] The difference between this example and Example 4 is that Example 4 uses 95% ethanol aqueous solution (10v) as the recrystallization solvent, while this example uses acetonitrile (10v) as the recrystallization solvent, and the ee value of the obtained sample is 87.2%.

[0112] The recrystallized product was subjected to a hydrolysis reaction at a pH of 10-11, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0113] Embodiment 7:

[0114] The difference between this example and Example 4 is that Example 4 uses 95% ethanol aqueous solution (10v) as the recrystallization solvent, while this example uses tetrahydrofuran (10v) as the recrystallization solvent, and the ee value of the obtained sample is 93.6%.

[0115] The recrystallized product was subjected to a hydrolysis reaction at a pH of 12-13, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0116] Embodiment 8:

[0117] The difference between this example and Example 4 is that Example 4 uses 95% ethanol aqueous solution (10v) as the recrystallization solvent, while this example uses anhydrous ethanol as the recrystallization solvent, and the ee value of the obtained sample is 96.2%.

[0118] The recrystallized product is subjected to a hydrolysis reaction at a pH of 9-10 to obtain (2S)-2-amino-3-(2,4-dibromophenyl)propionic acid tert-butyl ester by filtration.

[0119] Embodiment 9:

[0120] Add 30 mg of tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate to the reaction container in sequence, add acetone (27v) and stir to dissolve; add (2R,3R)-(-)-diphenylformyl-L-tartaric acid (0.6eq), stir at 40°C for 5h, after the reaction is completed, cool to 10°C to precipitate crystals, filter and vacuum dry to obtain a sample.

[0121] Recrystallization: Weigh the above sample and place it in a reaction container; add tetrahydrofuran (10v) at room temperature to obtain a suspension; raise the temperature to 50°C within half an hour, maintain stirring at 50°C for two hours; cool to 20°C at 5°C / h, keep stirring overnight; filter at room temperature, and vacuum dry the filter cake at 50°C. The ee value of the obtained sample is 78.2%.

[0122] The recrystallized product was subjected to a hydrolysis reaction at a pH of 10-11, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0123] Embodiment 10:

[0124] Weigh about 600 mg of tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate, place it in a 20 ml glass bottle, add 19.2 ml of acetone at room temperature, and stir to obtain a clear solution; weigh 0.6 eq of (2R,3R)-(-)-diphenylformyl-L-tartaric acid and add it to the glass bottle to obtain a suspension; raise the temperature to 50°C within half an hour, maintain 50°C and stir for two hours; cool to 20°C at 5°C / h, maintain stirring for about 23 hours; filter at room temperature, and dry the filter cake in vacuum at 50°C. (ee value: 80.36%, yield: 39.15%).

[0125] Recrystallization: Weigh the above sample into a reaction bottle, add 12V acetone at room temperature to obtain a suspension; raise the temperature to 50°C within half an hour, maintain 50°C and stir for two hours; cool to 20°C at 5°C / h, maintain stirring for about 17 hours; centrifuge, and dry the filter cake under vacuum. (EE value: 96.94%, yield: 92.03%)

[0126] The recrystallized product was subjected to a hydrolysis reaction at a pH of 10-11, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0127] Embodiment 11:

[0128] Weigh about 10 g of tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate and place it in a 1L jacketed reactor; add 320 ml of acetone at room temperature and stir to obtain a clear solution; weigh 0.6 equivalents of (2R,3R)-(-)-diphenylformyl-L-tartaric acid, dissolve it with a solvent, and add it to the jacketed reactor to obtain a suspension; heat to 50°C within half an hour, maintain stirring at 50°C for two hours; cool to 20°C at 5°C / h, maintain stirring for about 17 hours; filter with suction at room temperature, and dry the filter cake at 50°C in vacuum for about 6 hours (ee value: 93.36%, yield: 39.57%).

[0129] Recrystallization: weigh about 3 g of the product and place it in a 50 mL jacketed reactor; add 36 ml of acetone at room temperature to obtain a suspension; heat to 50°C within half an hour, maintain stirring at 50°C for two hours; cool the system to 20°C at 5°C / h, and keep stirring for about 17 hours; filter at room temperature, and dry the filter cake in vacuum at 50°C (ee value: 97.9%).

[0130] The recrystallized product was subjected to a hydrolysis reaction at a pH of 10-11, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0131] Embodiment 12:

[0132] Weigh about 50 g of tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate and place it in a 5L jacketed reactor; add 1600 ml of acetone at room temperature and stir to obtain a clear solution; weigh 0.6 equivalents of (2R, 3R)-(-)-diphenylformyl-L-tartaric acid, dissolve it with a solvent, and add it to the jacketed reactor to obtain a suspension; heat it to 50°C within half an hour, keep stirring at 50°C for two hours; cool it to 20°C at 5°C / h, keep stirring for about 20h; filter it with suction at room temperature, and dry the filter cake at 50°C in vacuum for about 10h (ee value: 90.52%, yield: 40.38%).

[0133] Recrystallization: weigh about 15 g of the product and place it in a 250 mL jacketed reactor; add 225 ml of acetone at room temperature to obtain a suspension; heat to 50°C within half an hour, maintain 50°C and stir for two hours; cool to 20°C at 5°C / h, maintain stirring for about 17 hours; filter at room temperature, and dry the filter cake in vacuum at 50°C (ee value: 99.3%).

[0134] The recrystallized product was subjected to a hydrolysis reaction at a pH of 10-11, and was liberated and filtered to obtain tert-butyl (2S)-2-amino-3-(2,4-dibromophenyl) propionate.

[0135] Comparative Example 1:

[0136] Add 1.0 g of tert-butyl 2-amino-3-(2,4-dibromophenyl)propionate and 8 ml of methyl tert-butyl ether to the reaction container in sequence; stir at 30-35°C for 12 h until the sample is dissolved, add 1.0 eq of (R)-(-)-mandelic acid (1.0 eq) and continue stirring at 40-45°C for 2 h, cool to 10°C, the sample is in a suspended state, and centrifuge sampling is performed for testing (ee: 0%).

[0137] Comparative Example 2:

[0138] To the reaction vessel, add 1.0 g of tert-butyl 2-amino-3-(2,4-dibromophenyl)propanoate and 12 ml of methyl tert-butyl ether-methanol solution (5:1) in sequence; after stirring until dissolved, add 0.5 eq of D-tartaric acid and stir at room temperature for 12 h until the sample is dissolved. Cool to 10°C, the sample is clear and no crystals are precipitated.

[0139] Comparative Example 3:

[0140] The difference between Comparative Example 3 and Example 1 is that Example 1 uses anhydrous ethanol as the solvent, while Comparative Example 3 uses acetonitrile as the solvent, and the ee value of the obtained sample is 6.0%.

[0141] Comparative Example 4:

[0142] The difference between Comparative Example 4 and Example 1 is that Example 1 uses N-acetyl-D-phenylalanine (0.6 eq) and anhydrous ethanol (16 v) as a resolution reagent and a solvent, respectively, while Comparative Example 4 uses L-camphorsulfonic acid (0.6 eq) as a resolution reagent and acetone (5 v) as a solvent, and the ee value of the obtained sample is 6.2%.

[0143] Comparative Example 5:

[0144] The difference between Comparative Example 5 and Comparative Example 4 is that Comparative Example 4 uses acetone (5v) as the solvent, while Comparative Example 5 uses acetonitrile (29v) as the solvent, and the ee value of the obtained sample is 0%.

[0145] Comparative Example 6:

[0146] The difference between Comparative Example 6 and Comparative Example 4 is that Comparative Example 4 uses L-camphorsulfonic acid (0.6 eq) as a resolution agent, while Comparative Example 6 uses L-cysteine ​​(0.6 eq) as a resolution agent, and the ee value of the obtained sample is 16.8%.

[0147] Comparative Example 7:

[0148] The difference between Comparative Example 7 and Comparative Example 6 is that Comparative Example 6 uses acetone (5v) as the solvent, while Comparative Example 7 uses 95% ethanol aqueous solution (5v) as the solvent, and the ee value of the obtained sample is 0%.

[0149] Structural Identification Example 1

[0150] Take the sample obtained in Example 12 and test it according to the above ee value test conditions. The test results are as follows: Figure 1 As shown in Table 1, Figure 1 is the chromatogram, Table 1 is Figure 1 Peak table for the chromatogram shown.

[0151] Table 1

[0152]

[0153] See also Figure 1 , 8.474 minutes is the chromatographic peak of the s-configuration (i.e., IM3(S)) product, accounting for 99.65% (see Table 1); 9.465 minutes is the chromatographic peak of the R-configuration (i.e., IM3(R)) product, accounting for only 0.35% (see Table 1). It can be seen that the method of the present invention can effectively separate the s-configuration.

[0154] Structural Identification Example 2

[0155] The product prepared in Example 8 of the present invention and ethyl acetate (5v) were added to the reaction vessel, and (Boc) was added at 20-25°C. 2 O (6.00eq.), DMAP (0.01eq.). Stir at 55-60°C for 6h. Add 2N ammonia water (5v) and stir for 12h. Separate the layers. Add saturated ammonium chloride solution (5v) to the organic phase and stir for 0.5h. Separate the layers. Concentrate the organic phase at 40-45°C until no distillation occurs, add n-heptane (1v) and distill once. Add n-heptane (5v) and cool to 0-5°C, filter and retain the mother liquor. Add 5% citric acid solution (5v) to the mother liquor, cool to 0-5°C and stir for 0.5h, let stand and separate the layers, concentrate the organic phase at 85-90°C until no distillation occurs, and obtain a light yellow solid. Add ethyl acetate (10v), replace with nitrogen once, and stir. Add AcOK (3.50eq.), B 2 Pin 2 (2.50 eq.) Nitrogen replacement once, stirring. Add Pd(dppf)Cl 2(0.10eq.), nitrogen replacement 3 times. Stir at 75-78℃ for 17h. Cool down to 20-25℃ under nitrogen protection, filter cake pad diatomaceous earth, filter, filter cake washed once with EA (1v), filter cake discarded. Filter the mother liquor under nitrogen protection, filter cake pad silica gel, filter cake washed once with EA (1v), filter cake discarded. Add activated carbon (1.0X) and silica gel (1.0X) to the filtrate and heat to 55-60℃ and stir for 0.5h. Cool down to 20-25℃ and filter, filter cake discarded. Add saturated ammonium chloride solution to the mother liquor and wash once, and discard the aqueous phase. Concentrate the mother liquor at 50-55℃ until no distillation. Add n-heptane (2v) and distill once. Add silica gel (3.0X) and n-heptane (5v) and concentrate until no distillation. Padded with silica gel for suction filtration, retain the mother liquor, and discard the filter cake. The mother liquor was concentrated at 50-55°C until no distillation occurred. n-heptane (5v) was added to dissolve. The temperature was lowered to -10-0°C for crystallization. The mixture was placed in an oven at 30-35°C for drying for 12 hours to obtain a white solid, namely N,N-di(tert-butyloxycarbonyl)-2,4-di(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-(2S)-2-yl)-phenylalanine tert-butyl ester.

[0156] The obtained white solid (N,N-di(tert-butyloxycarbonyl)-2,4-di(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-(2S)-2-yl)-phenylalanine tert-butyl ester) and N,N-di(tert-butyloxycarbonyl)-2,4-di(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-(2S)-2-yl)-phenylalanine tert-butyl ester reference substance [Batch No.: EW22935-28-P1(P2)-peak2-L; Source: Wuhan WuXi AppTec New Drug Development Co., Ltd.] were injected into supercritical fluid chromatography according to the chromatographic conditions shown in Table 2. The chromatograms are shown in Table 2. Figure 2 shown.

[0157] Table 2

[0158]

[0159] See also Figure 2 , N,N-di(tert-butyloxycarbonyl)-2,4-di(4,4,5,5-tetramethyl-1,3,2-dioxaborolane-(2S)-2-yl)-phenylalanine tert-butyl ester (see Figure 2 Curve ② in the figure and the reference substance (see Figure 2 The peak time of curve ①) in FIG. 1 is consistent, and the reference substance is a commercially available S-configuration compound, which shows that the phenylalanine derivatives obtained by the separation method of the present invention are of S configuration. Obviously, the separation intermediates and phenylalanine derivatives obtained by the method of the present invention are of S configuration, and the present invention can effectively separate the product of S configuration.

[0160] In summary, the splitting method of the present invention can not only effectively split the racemate and separate the required S configuration, but also be applicable to large-scale production with low cost and significant beneficial effects.

Claims

1. A method for chiral separation of phenylalanine derivatives represented by formula (I), X is selected from Br, I, F, Cl, CN, SCN or OCN; R 1 , R 2 Each independently selected from: hydrogen or tert-butyloxycarbonyl; R 3 Selected from tert-butyl; n = 1 or 2; in, The method comprises a splitting step: using a splitting reagent to react with a phenylalanine derivative shown in formula (I) in a reaction solvent to obtain a splitting intermediate; the splitting reagent is selected from N-acetyl-D-phenylalanine and / or (2R, 3R)-(-)-diphenylformyl-L-tartaric acid; and the reaction solvent is selected from 90-99% ethanol aqueous solution, anhydrous ethanol or acetone.

2. The chiral separation method according to claim 1, wherein: The splitting step comprises: using a splitting agent to react with the phenylalanine derivative shown in formula (I) in a reaction solvent, then crystallizing the reaction system at 10-30° C., filtering, and obtaining a split intermediate.

3. The chiral separation method according to claim 2, wherein: The method comprises stirring the reaction system at 10-30° C. for 10-25 hours to crystallize, and then filtering to obtain a resolved intermediate.

4. The chiral separation method according to any one of claims 1 to 3, wherein: The ee value of the compound represented by formula (II) in the resolved intermediate is greater than 35% A is a resolving agent.

5. The chiral separation method according to claim 4, wherein: The compound represented by formula (II) is selected from the compounds represented by formula (II-1) or formula (II-2):

6. The chiral separation method according to any one of claims 1 to 5, wherein: The reaction of the resolution agent with the phenylalanine derivative shown in formula (I) comprises reacting the resolution agent with the phenylalanine derivative shown in formula (I) at 30° C. to 55° C. to obtain a resolution intermediate.

7. The chiral separation method according to any one of claims 1 to 6, wherein: The reaction solvent is 90-99% ethanol aqueous solution, and the resolution reagent is N-acetyl-D-phenylalanine; or, The reaction solvent is acetone, and the resolution reagent is (2R, 3R)-(-)-diphenylformyl-L-tartaric acid.

8. The chiral separation method according to any one of claims 1 to 7, wherein: The molar ratio of the phenylalanine derivative represented by formula (I) to the resolution agent is 1:0.4-1.

0.

9. The chiral separation method according to any one of claims 1 to 8, wherein: The volume (mL) of the reaction solvent is 10 to 35 times the mass (g) of the phenylalanine derivative.

10. The chiral separation method according to any one of claims 1 to 9, wherein: The method further comprises: subjecting the obtained resolved intermediate to at least one recrystallization step in a recrystallization solvent.

11. The chiral separation method according to claim 10, wherein: The recrystallization comprises stirring the resolved intermediate obtained in the resolution step in a recrystallization solvent at 45-55° C. for 1.5-2.5 hours, and then stirring at 15-25° C. for 14-20 hours to obtain a recrystallized resolved intermediate.

12. The chiral separation method according to claim 10 or 11, wherein: The recrystallization comprises mixing the split intermediate with a recrystallization solvent to obtain a suspension, heating the suspension to 45-55° C. within 20-40 minutes, stirring for 1.5-2.5 hours, then cooling to 15-25° C. at a rate of 4-6° C. / h, stirring for 14-20 hours, and obtaining a recrystallized split intermediate.

13. The chiral separation method according to any one of claims 10 to 12, wherein: The recrystallization solvent is at least one selected from anhydrous ethanol, tetrahydrofuran, acetonitrile, acetone and 90-99% ethanol aqueous solution; and / or The volume (mL) of the recrystallization solvent is 9 to 15 times the mass (g) of the resolved intermediate.

14. The chiral separation method according to any one of claims 1 to 13, wherein: The method further comprises the step of hydrolyzing the split intermediate obtained in the splitting step or the split intermediate after recrystallization, and obtaining the phenylalanine derivative of formula (III) through hydrolysis.

15. The chiral separation method according to any one of claims 1 to 14, wherein: The mass of the phenylalanine derivative represented by formula (I) introduced into the separation step is 30mg-50g.

16. The chiral separation method according to any one of claims 1 to 15, wherein: The phenylalanine derivatives are selected from the following structures: X is independently selected from Br, I, F, Cl, CN, SCN or OCN; R 1 , R 2 Each independently selected from: hydrogen or tert-butyloxycarbonyl; R 3 Selected from tert-butyl.

17. The chiral separation method according to any one of claims 1 to 16, wherein: The phenylalanine derivative is selected from one of the following structures:

18. The intermediate represented by formula (II) in, X is selected from Br, I, F, Cl, CN, SCN or OCN; R 1 , R 2 Each independently selected from: hydrogen or tert-butyloxycarbonyl; R 3 Selected from tert-butyl; n = 1 or 2; A is a resolving agent.

19. The intermediate according to claim 18, wherein A is independently selected from N-acetyl-D-phenylalanine or (2R,3R)-(-)-diphenylformyl-L-tartaric acid.

Images