Method suitable for industrial production of aspartic acid derivative

Abstract

The invention discloses a method suitable for industrial production of an aspartic acid derivative, which comprises the following steps: A, taking L-aspartic acid as a starting material, and reacting with isobutene to obtain a mixture of H-Asp (OtBu)-OH and H-Asp-OtBu; and B, reacting the mixture obtained in the step A with 9-fluorenylmethyl-N-succinimido carbonate, treating to obtain a mixture of Fmoc-Asp (OtBu)-OH and Fmoc-Asp-OtBu, and separating and refining to obtain a target product. The preparation method provided by the invention is safe and environment-friendly, does not use heavy metal salts, strong oxidants, strong irritant reagents and other reagents, can simultaneously produce two amino acid derivative products, has the characteristics of low cost, high efficiency, stable product quality and the like, and is very suitable for industrial large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of pharmaceutical intermediate preparation, and in particular to a method suitable for industrial production of aspartic acid derivatives. Background Art

[0002] Fmoc-Asp(OtBu)-OH, systematic nomenclature: (2S)-4-tert-butoxy-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]amino}-4-oxobutanoic acid; Fmoc-Asp-OtBu, systematic nomenclature: (S)-3-{[(9H-fluoren-9-yl)methoxy]carbonyl}-4-tert-butoxy-4-oxobutanoic acid. Both are protected amino acids and are also organic synthesis intermediates and pharmaceutical intermediates. They can be used in biochemical research, organic synthesis, and pharmaceutical research and development. Their structural formulas are shown below:

[0003] Since L-aspartic acid (L-Asp) has two carboxyl groups in its molecular structure and has similar chemical properties, the reaction selectivity is poor. The current mainstream method for industrial production of Fmoc-Asp(OtBu)-OH is as follows (see patent document CN117586151A): A. L-aspartic acid (L-Asp) is used as the starting material and reacts with a tert-butyl donor (tert-butyl acetate, isobutylene, etc.) in the presence of a catalyst to produce a mixture of H-Asp(OtBu)-OH and H-Asp-OtBu (introducing a tert-butyl group). After reaching the reaction endpoint, a copper salt (such as copper sulfate) is added to form a complex with H-Asp(OtBu)-OH (H-Asp-OtBu cannot complex with copper ions). The addition of a copper salt is not required, but multiple purification steps are required in the next step to remove byproducts. B. H-Asp(OtBu)-OH reacts with 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) to obtain Fmoc-Asp(OtBu)-OH.

[0004] The specific steps are as follows:

[0005] Production practice has shown that no matter which tert-butyl donor is used for tert-butylation, the reaction selectivity is poor, that is, the by-product H-Asp-OtBu accounts for a high proportion. Therefore, heavy metal copper salts have to be used for complexation to separate the two. The waste liquid containing copper salts causes serious environmental pollution and has high treatment costs.

[0006] In this context, to address the problem of poor reaction selectivity, researchers have developed and improved processes, such as those disclosed in patent documents CN117865829A and CN108997155A. For example, the preparation method disclosed in patent document CN113292456A is: A. Using L-aspartic acid (L-Asp) as the starting material, react with phosphorus trichloride to obtain aspartic acid anhydride hydrochloride; B. Aspartic acid anhydride hydrochloride reacts with ethanol to produce H-Asp-OEt·HCl; C. H-Asp-OEt·HCl undergoes transesterification with tert-butyl acetate to produce H-Asp(OtBu)-OEt; D. H-Asp(OtBu)-OEt is hydrolyzed to obtain H-Asp(OtBu)-OH, which then reacts with 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) to obtain the target product Fmoc-Asp(OtBu)-OH.

[0007] The specific steps are shown in the figure below:

[0008] Through production practice, it is known that this method pre-protects the α-carboxyl group by first forming aspartic acid anhydride hydrochloride and then performing alcoholysis, which effectively solves the problem of reaction selectivity without using heavy metal salts. However, the steps are long, making the process more complicated, and the total yield is only about 20%. In addition, phosphorus trichloride is required, and this reagent is highly irritating and highly toxic. A large amount of acid mist is generated during the reaction, which requires high corrosion resistance of the equipment. In addition, a large amount of phosphorus-containing waste liquid is generated after the reaction, causing eutrophication of the water body, and the treatment cost is high.

[0009] Correspondingly, similar to the case of Fmoc-Asp(OtBu)-OH, the preparation of Fmoc-Asp-OtBu also faces the problem of reaction selectivity. The current mainstream method for industrial production of Fmoc-Asp-OtBu is: A. Using L-aspartic acid (L-Asp) as the starting material, aspartic acid anhydride hydrochloride is generated under the action of phosphorus trichloride or phosphorus oxychloride; B. Aspartic acid anhydride hydrochloride reacts with tert-butyl alcohol to obtain H-Asp-OtBu; C. H-Asp-OtBu reacts with Fmoc-OSu to obtain Fmoc-Asp-OtBu.

[0010] The specific steps are as follows:

[0011] The mainstream preparation method of Fmoc-Asp-OtBu also requires the use of phosphorus trichloride, and also faces problems with equipment corrosion resistance and waste liquid treatment. Summary of the Invention

[0012] The purpose of the present invention is to provide a simple, efficient and environmentally friendly method for industrial production of aspartic acid derivatives to address the above-mentioned problems, thereby overcoming the shortcomings of existing industrial production.

[0013] The technical solution adopted by the present invention is as follows: a method suitable for industrial production of aspartic acid derivatives, comprising the following steps: A. Using L-aspartic acid as the starting material, reacting with isobutylene to obtain a mixture of H-Asp(OtBu)-OH and H-Asp-OtBu; B. The mixture obtained in step A is reacted with 9-fluorenylmethyl-N-succinimidyl carbonate, and then treated to obtain a mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu, which is then separated and purified to obtain the target products Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu.

[0014] In the above method, the specific reaction equation involved is as follows:

[0015] Furthermore, in step A, L-aspartic acid is mixed with a reaction solvent and then reacted with isobutylene in the presence of an acidic catalyst.

[0016] Furthermore, the molar ratio of isobutylene to L-aspartic acid is 3.0-5.0:1, for example, 3.0:1, 3.5:1, 4.5:1, 5.0:1, etc. The molar ratio should not be too low or too high. If it is too low, the conversion rate of L-aspartic acid will be low, resulting in a decrease in the overall yield. If it is too high, the solubility of the materials will be affected, and the homogeneous reaction will be converted to a heterogeneous reaction, thereby reducing the conversion rate of L-aspartic acid.

[0017] Furthermore, when the acidic catalyst is added and L-aspartic acid reacts with isobutylene, the temperature of the reaction system is controlled within the range of 0-10° C. Excessively high temperature of the reaction system may cause isobutylene to escape from the reaction system, thereby causing a decrease in the conversion rate of L-aspartic acid.

[0018] Furthermore, the reaction solvent is an ether solvent, for example, a mixture of one or more of tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, etc. The weight ratio of the reaction solvent to L-aspartic acid is 5-15:1, for example, 5:1, 8:1, 10:1, 12:1, 15:1, etc.

[0019] Furthermore, the acidic catalyst is a protonic acid, which can be selected from one or more of sulfuric acid, toluenesulfonic acid, and methanesulfonic acid. When the acidic catalyst is a diprotic acid, the molar ratio of the acidic catalyst to L-aspartic acid is 1.5-3.0:1, for example, 1.5:1, 2.0:1, 2.4:1, 2.5:1, 3.0:1, etc. When the acidic catalyst is a monoprotic acid, the molar ratio of the acidic catalyst to L-aspartic acid is 3.0-6.0:1, for example, 3.0:1, 3.5:1, 4.0:1, 4.8:1, 5.0:1, 6.0:1, etc.

[0020] Furthermore, in step A, after isobutylene reacts with L-aspartic acid, the pH value of the reaction system is adjusted to neutral, and then washed with an organic solvent, and the aqueous phase is separated to obtain a mixture of H-Asp(OtBu)-OH and H-Asp-OtBu.

[0021] Furthermore, in step B, the pH value of the mixture obtained in step A is adjusted to 8-9, the mixture is mixed with an organic solvent (for example, ethyl acetate), 9-fluorenylmethyl-N-succinimidyl carbonate is added in batches, and the reaction temperature is controlled to be 15-30°C (for example, 15°C, 20°C, 22°C, 24°C, 25°C, 30°C, etc.). After the reaction is completed, the organic phase is separated and concentrated to obtain a mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu.

[0022] Furthermore, the reaction temperature of the mixture of H-Asp(OtBu)-OH and H-Asp-OtBu with 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) should not be too low or too high. If it is too low, the reaction will be slow and the working hours will be increased. If it is too high, impurities such as Fmoc-Asp(OtBu)-OtBu, Fmoc-β-Ala-Asp(OtBu)-OH, and Fmoc-β-Ala-OH will be easily generated.

[0023] Furthermore, the separation system for the mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu is a halogenated hydrocarbon + saturated alkane system, for example, chloroform + n-hexane, trichloroethane + cyclohexane, etc., and the weight ratio of the halogenated hydrocarbon to the saturated alkane is 1:0.8-3.0, for example, 1:0.8, 1:1, 1:1.5, 1:2.0, 1:2.5, 1:3.0, etc. The weight ratio of the halogenated hydrocarbon to the saturated alkane should not be too low or too high, as too low or too high will increase the number of separations and thus increase the working time.

[0024] Further, the refining system after Fmoc-Asp(OtBu)-OH is separated from Fmoc-Asp-OtBu is an organic solvent + water system, the organic solvent can be acetone, ethanol, acetonitrile, etc., the weight ratio of the organic solvent to water is 1:2-5, for example, it can be 1:2, 1:3, 1:4, 1:5, etc.

[0025] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present application are: 1. Unlike mainstream industrial production processes, the present application adopts L-Asp to react with isobutene to obtain a mixture of H-Asp(OtBu)-OH and H-Asp-OtBu, without refining or separating the mixture, but directly reacting with Fmoc-OSu to obtain a mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu, and then separating and refining the mixture to obtain the two target products; through production test summary, it is found that this production process not only does not use heavy metal salts, strong oxidizing agents and strong irritants, but also has fewer production procedures, low cost, high efficiency, stable product quality and obvious technical advantages; 2. The production process of the present application can obtain two kinds of amino acid derivative products at the same time, which is equivalent to combining two processes into one process, which not only greatly shortens the production cycle, but also avoids the waste of by-products and the high-cost treatment of subsequent waste liquid, maximizes the utilization rate of production raw materials, and is very suitable for industrial scale production. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0027] Example 1 A method suitable for industrial production of aspartic acid derivatives, comprising the following steps: (1) Preparation of intermediates S11, add tetrahydrofuran 1500 kg, L-Asp 150 kg (weight ratio 10:1) into a 3000 L glass-lined reaction kettle, start stirring at 50 Hz, control the temperature in the range of 0-10℃, and then add sulfuric acid 225 kg (molar ratio 2.0:1); S12, after adding sulfuric acid, continue to control the temperature in the range of 0-10℃, then pass in isobutene 270 kg (molar ratio 5.0:1), after adding, keep the temperature at 0-10℃ and react for 72 h; S13, adjusting the pH of the reaction solution to 7-8 with 20% (mass percentage, the same below) potassium carbonate aqueous solution, then washing the reaction solution twice with 150 kg of ethyl acetate, separating the aqueous phase and the organic phase, and directly feeding the aqueous phase into the next reaction; (2) Preparation of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu: S21, add 20% potassium carbonate aqueous solution to the aqueous phase obtained in the previous step to adjust the pH to 8-9, add 600 kg of ethyl acetate, start stirring at 50 Hz, and then add 210 kg of Fmoc-OSu in batches; S22. After the addition of Fmoc-OSu, the temperature was controlled at 20-24°C for reaction. The reaction was monitored by TLC (thin layer chromatography) until the reaction of Fmoc-OSu was basically complete. The mixture was allowed to stand for separation. The organic phase was set aside. The aqueous phase was extracted with 600 kg of ethyl acetate. The organic phases were combined and concentrated under reduced pressure at 50°C to obtain a concentrate of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu. (3) Separation and purification of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu S31. Add 300 kg of chloroform to the concentrate obtained in the previous step to dissolve it, then dropwise add 300 kg of n-hexane (chloroform:n-hexane weight ratio = 1:1), stir and crystallize for 2 hours, then centrifuge. Repeat the above steps until Fmoc-Asp-OtBu in the solid no longer changes as monitored by TLC, and then centrifuge; S32. Dissolve the centrifuged solid in 300 kg of acetone, then dropwise add 900 kg of water (acetone:water weight ratio = 1:3). Stir and crystallize for 2 h, then centrifuge and dry at 45-55°C to obtain 183 kg of a white solid (Fmoc-Asp(OtBu)-OH, molecular weight 411.45). The purity determined by HPLC is 99.8%. S33. Concentrate the liquid phase (chloroform + n-hexane solution) after centrifugation under reduced pressure at 50°C, dissolve the concentrate in 300 kg of acetone, and then add 900 kg of water (acetone: water weight ratio = 1:3) dropwise. After stirring and crystallizing for 2 hours, centrifuge and dry at 45-55°C to obtain 95 kg of white solid (Fmoc-Asp-OtBu, molecular weight 411.45). The purity detected by HPLC is 99.5%.

[0028] Calculation showed that the yield of Fmoc-Asp(OtBu)-OH was 39.5%, the yield of Fmoc-Asp-OtBu was 20.5%, and the total yield was 60.0%.

[0029] Example 2 A method suitable for industrial production of aspartic acid derivatives comprises the following steps: (1) Preparation of intermediates S11. Add 1200 kg of ethylene glycol dimethyl ether and 150 kg of L-Asp (weight ratio 8:1) to a 3000 L glass-lined reactor, start stirring at 50 Hz, control the temperature between 0-10°C, and add dropwise 433 kg of methane sulfonic acid (molar ratio 4.0:1); S12, after the addition of methanesulfonic acid is completed, the temperature is continued to be controlled in the range of 0-10°C, and then 243 kg of isobutylene (molar ratio 4.5:1) is introduced. After the addition is completed, the temperature is maintained at 0-10°C and the reaction is carried out for 72 hours; S13, the pH value of the reaction solution was adjusted to 7-8 with 20% potassium carbonate aqueous solution, and the reaction solution was washed twice with 150 kg of ethyl acetate, and the aqueous phase and the organic phase were separated, and the aqueous phase was directly put into the next step of reaction; (2) Preparation of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu: S21, add 20% potassium carbonate aqueous solution to the aqueous phase obtained in the previous step to adjust the pH to 8-9, add 600 kg of ethyl acetate, start stirring at 50 Hz, and then add 225 kg of Fmoc-OSu in batches; After the addition of S22 and Fmoc-OSu, the temperature was controlled at 18-22°C for reaction. The reaction was monitored by TLC until the reaction of Fmoc-OSu was basically completed. The mixture was allowed to stand for separation. The organic phase was set aside. The aqueous phase was extracted with 600 kg of ethyl acetate. The organic phases were combined and concentrated under reduced pressure at 50°C to obtain a concentrate of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu. (3) Separation and purification of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu S31. Add 300 kg of trichloroethane to the concentrate obtained in the previous step to dissolve it, then dropwise add 300 kg of n-heptane (trichloroethane:n-heptane weight ratio = 1:1.2), stir and crystallize for 2 hours, then centrifuge. Repeat the above steps until Fmoc-Asp-OtBu in the solid no longer changes as monitored by TLC, and then centrifuge; S32. Dissolve the centrifuged solid in 300 kg of ethanol, then add dropwise 1200 kg of water (ethanol:water weight ratio = 1:4). Stir and crystallize for 2 h, then centrifuge and dry at 45-55°C to obtain 189 kg of a white solid (Fmoc-Asp(OtBu)-OH, molecular weight 411.45). The purity determined by HPLC is 99.6%. S33, the liquid phase (trichloroethane + n-heptane solution) after centrifugation is concentrated at 50℃ under reduced pressure, the concentrated solution is dissolved with 300kg of ethanol, and then 1200kg of water is added dropwise (ethanol: water weight ratio = 1:4), after stirring for 2h, centrifugation and drying at 45-55℃, white solid 97kg (Fmoc-Asp-OtBu, molecular weight 411.45) is obtained, and the purity detected by HPLC is 99.4%.

[0030] The yield of Fmoc-Asp(OtBu)-OH is 40.8%, the yield of Fmoc-Asp-OtBu is 20.9%, and the total yield of both is 61.7%.

[0031] Example 3 A method suitable for industrial production of aspartic acid derivatives, comprising the following steps: (1) Preparation of intermediates S11, add dioxane 1350kg, L-Asp 150kg (weight ratio 9:1) to a 3000L glass-lined reactor, start stirring at 50Hz, control the temperature in the range of 0-10℃, and then add toluenesulfonic acid 679kg (molar ratio 3.5:1); S12, after adding toluenesulfonic acid, continue to control the temperature in the range of 0-10℃, then pass in isobutene 216kg (molar ratio 4.0:1), after adding, keep the temperature at 0-10℃ for 72h; S13, adjust the pH value of the reaction solution to 7-8 with 20% potassium carbonate aqueous solution, then wash the reaction solution with 150kg of ethyl acetate twice, separate the water phase and the organic phase, and directly put the water phase into the next step reaction; (2) Preparation of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu: S21, add 20% potassium carbonate aqueous solution to the water phase obtained in the previous step to adjust the pH value to 8-9, add 600kg of ethyl acetate, start stirring at 50Hz, then add Fmoc-OSu 216kg in batches; S22, after adding Fmoc-OSu, control the temperature at 19-23℃ for reaction, monitor by TLC until Fmoc-OSu is basically completely reacted, stand for separation, the organic phase is reserved, and the water phase is extracted with 600kg of ethyl acetate, the organic phases are combined, and the organic phase is concentrated under reduced pressure at 50℃ to obtain the concentrate of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu; (3) Separation and purification of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu S31. Add 300 kg of dichloromethane to the concentrate obtained in the previous step to dissolve it, then dropwise add 300 kg of cyclohexane (trichloroethane:n-heptane weight ratio = 1:1.5), stir and crystallize for 2 hours, then centrifuge. Repeat the above steps until Fmoc-Asp-OtBu in the solid no longer changes as monitored by TLC, and then centrifuge; S32. Dissolve the centrifuged solid in 300 kg of acetonitrile, then add dropwise 1050 kg of water (acetonitrile:water weight ratio = 1:3.5). Stir and crystallize for 2 h, then centrifuge and dry at 45-55°C to obtain 176 kg of a white solid (Fmoc-Asp(OtBu)-OH, molecular weight 411.45). The purity determined by HPLC is 99.6%. S33. The liquid phase (dichloromethane + cyclohexane solution) after centrifugation was concentrated under reduced pressure at 50°C, and the concentrate was dissolved in 300 kg of acetonitrile. 1050 kg of water (acetonitrile: water weight ratio = 1:3.5) was added dropwise. After stirring and crystallization for 2 hours, the mixture was centrifuged and dried at 45-55°C to obtain 96 kg of white solid (Fmoc-Asp-OtBu, molecular weight 411.45). The purity detected by HPLC was 99.3%.

[0032] Calculation showed that the yield of Fmoc-Asp(OtBu)-OH was 38.0%, the yield of Fmoc-Asp-OtBu was 20.7%, and the total yield was 58.7%.

[0033] Comparative Example 1 This comparative example prepares Fmoc-Asp(OtBu)-OH according to the mainstream method of industrial production, including the following steps: (1) Preparation of H-Asp(OtBu)-OH S11. Add 1130 kg of tert-butyl acetate to a 3000 L glass-lined reactor, start stirring at 50 Hz, add 150 kg of L-Asp, control the temperature at 0-10° C., and dropwise add 194 kg of perchloric acid; after the addition, control the temperature at 0-10° C. and react for 72 hours; S12, after the reaction is completed, the pH value is adjusted to 8-9 with 20% potassium carbonate aqueous solution, and then washed twice with 150 kg of ethyl acetate, and the aqueous phase is directly put into the next step of reaction; (2) Preparation of Fmoc-Asp(OtBu)-OH S21, add 600 kg of ethyl acetate to the aqueous phase obtained in the previous step, control the temperature at 15-25 ° C, and add 205 kg of Fmoc-OSu in batches; S22, after the addition is completed, the temperature is controlled at 15-25 ° C, and the reaction is monitored by TLC until the Fmoc-OSu reaction is complete. The liquid is allowed to stand and separated, and the organic phase is set aside. The aqueous phase is extracted with 300 kg of ethyl acetate, and the organic phases are combined and concentrated under reduced pressure at 50 ° C. After the concentration is completed, 270 kg of petroleum ether is added, and the mixture is stirred for 3 hours and then centrifuged to obtain a solid; S23. Add 250 kg of ethanol to a 3000 L glass-lined reactor, start stirring at 50 Hz, add the above centrifuged solid, heat to dissolve, and then add 250 kg of water dropwise; after the addition is completed, stir and crystallize for 2 hours, centrifuge, and repeat the above operation until no Fmoc-Asp-OtBu spots are detected by TLC; dry at 45-55°C to obtain 152 kg of white solid (Fmoc-Asp(OtBu)-OH, molecular weight 411.45), with a total yield of 32.8% and a purity of 99.7% detected by HPLC.

[0034] Comparative Example 2 This comparative example prepared Fmoc-Asp(OtBu)-OH according to the preparation method disclosed in patent document CN113292456A, comprising the following steps: (1) Preparation of aspartic acid anhydride hydrochloride S11. Add 564 kg of tetrahydrofuran to a 3000 L glass-lined reactor, start stirring at 50 Hz, and add 150 kg of L-Asp; after the addition is complete, add 165 kg of phosphorus trichloride dropwise; S21, after the addition, the temperature was controlled at 40-45 ° C for reaction, and the reaction endpoint was monitored by TLC; after the reaction was completed, the temperature was lowered to below 30 ° C, centrifuged, and the obtained solid was slurried with 300 kg of petroleum ether for 2 h, centrifuged, and the obtained solid was directly used for the next reaction; (2) Preparation of H-Asp-OEt·HCl S21, add 330 kg of ethanol to a 3000 L glass-lined reactor, start stirring at 50 Hz, cool to -5-5 ° C, control the temperature at -5-5 ° C, and add the solid obtained in the previous step; S22, after the addition, the temperature was controlled at -5-5 ° C for 6 hours, and then the temperature was raised to 0-10 ° C for reaction, and the reaction end point was monitored by TLC; after the reaction was completed, 150 kg of ethanol was added at 0-10 ° C, and the pH value was adjusted to 6-7 with triethylamine, and the mixture was stirred for crystallization for 2 hours and then centrifuged; S23. Dissolve the centrifuged solid in 450 kg of ethanol:water (1:1 volume ratio) by heating, filter while hot, cool the filtrate to 4-8°C, stir and crystallize for 2 h, centrifuge, and dry at 50-60°C to obtain 121 kg of a white solid (H-Asp-OEt, molecular weight 197.62). (3) Preparation of H-Asp(OtBu)-OEt S31. Add 640 kg of tert-butyl acetate to a 3000 L glass-lined reactor, start stirring at 50 Hz, add 121 kg of H-Asp-OEt·HCl, cool to -5-0°C, and add 66 kg of perchloric acid dropwise while controlling the temperature at -5-0°C. After the addition, control the temperature at 10-15°C and react for 36 hours. Monitor the reaction endpoint by TLC. S32, after the reaction is completed, cool to 0-5 ° C, wash the organic phase with 120 kg of 0.5N hydrochloric acid, combine the aqueous phases, add 120 kg of ethyl acetate, adjust the pH to 7.5 with solid sodium bicarbonate, separate the layers, set the organic phase aside, extract the aqueous phase with 160 kg of ethyl acetate each time, and monitor the endpoint by TLC; S33. Combine the organic phases and wash with 120 kg of 10% sodium chloride aqueous solution each time. Monitor the organic phase for the absence of L-Asp by TLC. Add 200 kg of anhydrous sodium sulfate and dry for 4 hours, controlling the temperature below 10°C. Remove insoluble matter by filtration, and concentrate the filtrate under reduced pressure at 50-60°C to obtain 170 kg of a colorless oil (H-Asp(OtBu)-OEt, molecular weight 217.26). (4) Preparation of Fmoc-Asp(OtBu)-OH S41. Add 400 kg of tetrahydrofuran, 100 kg of water, and the oil from the previous step to a 3000 L glass-lined reactor, start stirring at 50 Hz, adjust the pH to 9.5-10.5 with 2N aqueous sodium hydroxide solution, maintain this pH at 15-20° C., and monitor the reaction endpoint by TLC. S42, after the reaction is complete, add 280 kg of Fmoc-OSu in batches while controlling the temperature at 5-10°C, and maintain the pH value at 7-8 with solid sodium carbonate; after the addition is complete, control the temperature at 5-10°C for reaction, and monitor the reaction endpoint by TLC; S43, after the reaction is completed, the insoluble matter is filtered off, and the filtrate is used to remove impurities with petroleum ether, 200 kg each time, and the end point is monitored by TLC. 600 kg of ethyl acetate is added and then acidified and extracted. The organic phase is set aside, and the aqueous phase is extracted twice with ethyl acetate, 200 kg each time; S44. Combine the organic phases, wash with 10% sodium chloride aqueous solution to a pH of 5-6, dry with 200 kg of anhydrous sodium sulfate for 2 h, filter out insoluble matter, and concentrate the filtrate under reduced pressure at 45-50°C. Add 200 kg of petroleum ether and crystallize for 2 h. Centrifuge and dry at 45-55°C to obtain 132 kg of a white solid (Fmoc-Asp(OtBu)-OH, molecular weight 411.45). The total yield is 28.5%, and the purity determined by HPLC is 99.2%.

[0035] Comparative Example 3 This comparative example prepares Fmoc-Asp-OtBu according to the mainstream method of industrial production, including the following steps: (1) Preparation of aspartic acid anhydride hydrochloride S11. Add 564 kg of tetrahydrofuran to a 3000 L glass-lined reactor, start stirring at 50 Hz, add 150 kg of L-Asp, and after the addition is complete, add 165 kg of phosphorus trichloride dropwise; after the addition is complete, control the temperature at 40-45° C. to react, and monitor the reaction endpoint by TLC; S12, after the reaction is completed, cool to below 30°C, centrifuge, beat the obtained solid with 300 kg of petroleum ether for 2 hours, centrifuge, and directly use the obtained solid for the next reaction; (2) Preparation of H-Asp-OtBu: S21. Add 670 kg of tert-butyl alcohol to a 3000 L glass-lined reactor, start stirring at 50 Hz, cool to -5-5°C, and add the solid obtained in the previous step at -5-5°C; after the addition, control the temperature at -5-5°C to react for 6 h, then raise the temperature to 0-10°C to react, and monitor the reaction endpoint by TLC; S22, after the reaction is completed, add 1340 kg of water, control the temperature at 0-10 ° C, adjust the pH value to 7-8 with potassium carbonate aqueous solution, and directly put it into the next step of reaction (H-Asp-OtBu, molecular weight 189.21); (3) Preparation of Fmoc-Asp-OtBu: S31, adding 228 kg of Fmoc-OSu in batches to the solution obtained in the previous step while controlling the temperature at 15-25°C, and maintaining the pH at 8-9 with potassium carbonate; after the addition, controlling the temperature at 15-25°C to react, and monitoring the reaction endpoint by TLC; S32, after the reaction is completed, remove impurities with petroleum ether, 200 kg each time, monitor the end point by TLC, add 400 kg of ethyl acetate and acidify and extract, the organic phase is set aside, and the aqueous phase is extracted twice with ethyl acetate, 100 kg each time; S33. Combine the organic phases, wash with 20% aqueous sodium chloride solution to a pH of 5-6, dry with 200 kg of anhydrous sodium sulfate for 2 h, filter out insoluble matter, and concentrate the filtrate under reduced pressure at 45-50°C. Add 200 kg of petroleum ether and crystallize for 2 h. Centrifuge and dry at 45-55°C to obtain 248 kg of a white solid (Fmoc-Asp-OtBu, molecular weight 411.45). The total yield is 53.5%, and the purity determined by HPLC is 99.3%.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method suitable for industrial production of aspartic acid derivatives, characterized in that: The steps include: A. Using L-aspartic acid as the starting material, reacting with isobutylene to obtain a mixture of H-Asp(OtBu)-OH and H-Asp-OtBu; B. The mixture obtained in step A is reacted with 9-fluorenylmethyl-N-succinimidyl carbonate, and then treated to obtain a mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu, which is then separated and purified to obtain the target products Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu.

2. The method according to claim 1, wherein In step A, L-aspartic acid is mixed with a reaction solvent and then reacted with isobutylene in the presence of an acidic catalyst.

3. The method according to claim 2, wherein The molar ratio of isobutylene to L-aspartic acid is 3.0-5.0:

1.

4. The method according to claim 3, wherein When the acidic catalyst is added and L-aspartic acid reacts with isobutylene, the temperature of the reaction system is controlled within the range of 0-10°C.

5. The method according to claim 3, wherein The reaction solvent is an ether solvent, and the weight ratio of the reaction solvent to L-aspartic acid is 5-15:

1.

6. The method according to claim 3, wherein The acidic catalyst is selected from one or more of sulfuric acid, toluenesulfonic acid, and methanesulfonic acid; when the acidic catalyst is a dibasic acid, the molar ratio of the acidic catalyst to L-aspartic acid is 1.5-3.0:1; when the acidic catalyst is a monobasic acid, the molar ratio of the acidic catalyst to L-aspartic acid is 3.0-6.0:

1.

7. The method according to claim 1, wherein In step A, after isobutylene reacts with L-aspartic acid, the pH value of the reaction system is adjusted to neutral, and then washed with an organic solvent, and the aqueous phase is separated to obtain a mixture of H-Asp(OtBu)-OH and H-Asp-OtBu.

8. The method according to any one of claims 1 to 7, wherein: In step B, the pH value of the mixture obtained in step A is adjusted to 8-9, the mixture is mixed with an organic solvent, 9-fluorenylmethyl-N-succinimidyl carbonate is added in batches, and the reaction temperature is controlled to be 15-30° C. After the reaction is completed, the organic phase is separated and concentrated to obtain a mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu.

9. The method according to claim 8, wherein The separation system of the mixture of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu is a halogenated hydrocarbon + saturated alkane system, and the weight ratio of the halogenated hydrocarbon to the saturated alkane is 1:0.8-3.

0.

10. The method according to claim 9, wherein The purification system after separation of Fmoc-Asp(OtBu)-OH and Fmoc-Asp-OtBu is an organic solvent + water system, and the weight ratio of the organic solvent to water is 1:2-5.

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