A method for efficiently preparing high-purity Fmoc-ser (tBu)-OH

Abstract

The application discloses a high-efficiency preparation method of high-purity Fmoc-Ser(tBu)-OH, and belongs to the field of medical intermediates. The method comprises the following steps: reacting Ser, methanol and thionyl chloride to obtain H-Ser-OMeHCl; dissolving H-Ser-OMeHCl in t-butyl acetate, and then reacting with di-t-butyl dicarbonate under the action of perchlorate to obtain H-Ser(tBu)-OMe; subsequently, hydrolyzing the product to obtain H-Ser(tBu)-OH; and reacting H-Ser(tBu)-OH with Fmoc-OSu to obtain Fmoc-Ser(tBu)-OH, wherein the mass ratio of t-butyl acetate to H-Ser-OMeHCl is (5-10):1; the molar ratio of perchlorate to H-Ser-OMeHCl is (0.1-0.5):1; and the molar ratio of di-t-butyl dicarbonate to H-Ser-OMeHCl is (2-6):1. In the preparation of the intermediate, t-butyl acetate is innovatively selected as a solvent, perchlorate is innovatively selected as a catalyst, and di-t-butyl dicarbonate is innovatively selected as a t-butyl donor; the perchlorate, t-butyl acetate and di-t-butyl dicarbonate produce a synergistic effect in a specific proportion range, thereby significantly shortening the preparation period of Fmoc-Ser(tBu)-OH and greatly improving the product quality.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical intermediates, specifically relating to an efficient method for preparing high-purity Fmoc-Ser(tBu)-OH. Background Technology

[0002] Fmoc-Ser(tBu)-OH, systematically named N-(9-fluorenylmethoxycarbonyl)-O-tert-butyl-serine, is a protected amino acid and an organic synthesis and pharmaceutical intermediate. It can be used in biochemical research, organic synthesis, and pharmaceutical development. Its chemical structure is as follows:

[0003] Because the hydroxyl and carboxyl groups in the serine (L-configuration) molecule have similar chemical properties, to prevent side reactions and considering the solubility of the material, the carboxyl group is usually pre-protected, the hydroxyl group is tert-butylated, the pre-protection is removed, and finally the desired protecting group is introduced onto the amino group. CN 116082190 A discloses an efficient industrial production method for Fmoc-Ser(tBu)-OH, which is also the mainstream method for current industrial production, including the following steps: A. Starting with Ser, it reacts with methanol to obtain serine methyl ester hydrochloride [H-Ser-OMe·HCl] (carboxyl preprotection). BH-Ser-OMe·HCl reacts with isobutylene under strong acid catalysis to give O-tert-butyl-serine methyl ester [H-Ser(tBu)-OMe]; CH-Ser(tBu)-OMe was hydrolyzed to give O-tert-butyl-serine [H-Ser(tBu)-OH]; DH-Ser(tBu)-OH reacts with 9-fluorenylmethyl-N-succinimide carbonate (Fmoc-OSu) to give Fmoc-Ser(tBu)-OH.

[0004] The reaction formula is shown below:

[0005] This method has the following drawbacks in preparing the intermediate H-Ser(tBu)-OMe: First, it requires the use of gaseous materials with a risk of combustion and explosion, which places high demands on the airtightness of the production equipment and poses a safety risk; Second, the reaction time is long and the conversion is incomplete, which leads to the generation of impurities Fmoc-Ser-OH in subsequent steps, resulting in the waste of material Fmoc-OSu and increasing material costs. Summary of the Invention

[0006] To address the above problems, this invention provides an efficient method for preparing high-purity Fmoc-Ser(tBu)-OH.

[0007] Unless otherwise specified, all serine and its derivatives involved in this invention are L-configured, and the L-configuration is omitted in all molecular formulas. The technical solution of this invention is as follows: An efficient method for preparing high-purity Fmoc-Ser(tBu)-OH includes the following steps: Serine (serine) was mixed thoroughly with methanol (MeOH), and then thionyl chloride (SOCl2) was added dropwise to produce H-Ser-OMe. HCl; H-Ser-OMe After HCl is dissolved in tert-butyl acetate, it reacts with ditert-butyl dicarbonate [(Boc)2O] in the presence of perchlorate to give H-Ser(tBu)-OMe; Hydrolyzing H-Ser(tBu)-OMe yields H-Ser(tBu)-OH; H-Ser(tBu)-OH reacts with Fmoc-OSu to obtain Fmoc-Ser(tBu)-OH. Among them, tert-butyl acetate and H-Ser-OMe The mass ratio of HCl is (5~10):1; perchlorate and H-Ser-OMe The molar ratio of HCl is (0.1~0.5):1; ditert-butyl dicarbonate and H-Ser-OMe The molar ratio of HCl is (2~6):1.

[0008] This invention provides an efficient method for preparing high-purity Fmoc-Ser(tBu)-OH, the reaction formula of which is as follows:

[0009] In the synthesis of the intermediate H-Ser(tBu)-OMe, this invention innovatively selects tert-butyl acetate as a solvent, perchlorate as a catalyst, and ditert-butyl dicarbonate as a tert-butyl donor, especially when tert-butyl acetate reacts with H-Ser-OMe. The mass ratio of HCl is (5~10):1, and the perchlorate is reacted with H-Ser-OMe. The molar ratio of HCl is (0.1~0.5):1, and di-tert-butyl dicarbonate is mixed with H-Ser-OMe. When the molar ratio of HCl is (2~6):1, the three components produce a synergistic effect, which shortens the preparation cycle of the finished product Fmoc-Ser(tBu)-OH by about 1 / 4, while significantly improving the quality. The total yield is not less than 75%, the purity is not less than 99.5%, and the maximum single impurity is less than 0.1%. In addition, since di-tert-butyl dicarbonate is used to replace isobutylene, a gaseous material in the mainstream process, as the tert-butyl donor, the safety risks and the requirements for equipment airtightness are significantly reduced.

[0010] Preferably, the perchlorate is one or more of magnesium perchlorate, zinc perchlorate, calcium perchlorate, strontium perchlorate, or barium perchlorate.

[0011] Preferably, tert-butyl acetate and H-Ser-OMe The mass ratio of HCl is (5~8):1; more preferably, tert-butyl acetate and H-Ser-OMe The mass ratio of HCl is (5~6):1.

[0012] Preferably, perchlorate and H-Ser-OMe The molar ratio of HCl is (0.1~0.3):1; more preferably, perchlorate and H-Ser-OMe The molar ratio of HCl is (0.1~0.2):1.

[0013] Preferably, di-tert-butyl dicarbonate and H-Ser-OMe The molar ratio of HCl is (3~4):1; more preferably, di-tert-butyl dicarbonate and H-Ser-OMe The molar ratio of HCl is (3~3.5):1.

[0014] Preferably, H-Ser(tBu)-OMe is hydrolyzed under alkaline conditions to obtain H-Ser(tBu)-OH; more preferably, the alkaline conditions are aqueous solutions of alkali metal hydroxides; even more preferably, the alkali metal hydroxide is one or both of sodium hydroxide and potassium hydroxide; even more preferably, the molar ratio of alkali metal hydroxide to H-Ser(tBu)-OMe is (1.2~2.5):1; particularly preferably, the molar ratio of alkali metal hydroxide to H-Ser(tBu)-OMe is (1.2~1.5):1.

[0015] Preferably, H-Ser-OMe After HCl is dissolved in tert-butyl acetate, it reacts with ditert-butyl dicarbonate under the action of perchlorate at a temperature of 10~30℃; more preferably, the temperature is 15~25℃; and even more preferably, the temperature is 18~23℃.

[0016] Preferably, Fmoc-Ser(tBu)-OH is purified after being obtained; more preferably, the purification is carried out in a mixture of organic solvent and water; even more preferably, the organic solvent is one or more of methanol, ethanol or acetone; even more preferably, the mass ratio of organic solvent to water in the mixture of organic solvent and water is 1:(1~5); particularly preferably, the mass ratio of organic solvent to water is 1:(2~4).

[0017] Preferably, the reaction temperature of H-Ser(tBu)-OH with Fmoc-OSu is 10~30℃; more preferably, the temperature is 15~25℃; and even more preferably, the temperature is 20~25℃.

[0018] The beneficial effects of this invention are as follows: (1) In the synthesis of the intermediate product H-Ser(tBu)-OMe, this invention innovatively selects tert-butyl acetate as a solvent, perchlorate as a catalyst, and di-tert-butyl dicarbonate as a tert-butyl donor. Compared with the use of tert-butyl acetate and di-tert-butyl dicarbonate alone, or the combination of perchlorate and di-tert-butyl dicarbonate, the three components in a specific ratio [tert-butyl acetate and H-Ser-OMe]... The mass ratio of HCl is (5~10):1, and the perchlorate is reacted with H-Ser-OMe. The molar ratio of HCl is (0.1~0.5):1, and di-tert-butyl dicarbonate is mixed with H-Ser-OMe. The combined use of HCl at a molar ratio of (2~6)∶1] can significantly shorten the preparation cycle of the finished product Fmoc-Ser(tBu)-OH (by about 1 / 4), while greatly improving the quality of the finished product (total yield of the finished product is not less than 75%, purity is not less than 99.5%, and maximum single impurity is less than 0.1%), making it suitable for industrial-scale production.

[0019] (2) In preparing the finished product Fmoc-Ser(tBu)-OH, the present invention innovatively uses ditert-butyl dicarbonate to replace isobutylene, a gaseous material in the mainstream process, which significantly reduces safety risks and equipment requirements. Detailed Implementation

[0020] The specific embodiments listed in this invention are merely examples, and the invention is not limited to the specific embodiments described below. For those skilled in the art, any equivalent modifications and substitutions to the embodiments described below are also within the scope of this invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of this invention should be covered within its scope. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are commercially available conventional products. To better illustrate this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this invention can be practiced even without certain specific details. In other embodiments, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of this invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Unless otherwise specified, all units used in this specification are International Standard Units (SI), and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors unavoidable in industrial production.

[0022] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0023] In both the examples and comparative examples, the synthesis was carried out in a 3000L glass-lined reactor; the reaction process was monitored by thin-layer chromatography (TLC); and the purity was detected by HPLC.

[0024] Example 1 This embodiment provides an efficient method for preparing high-purity Fmoc-Ser(tBu)-OH, the steps of which are as follows: S1. Synthesis of H-Ser-OMe HCl: Add 1000 kg of methanol to 100 kg of Ser, and adjust the frequency converter to 50 Hz; add 170 kg of thionyl chloride dropwise while controlling the temperature at 10-20℃. After the addition is complete, raise the temperature to 50-60℃ and react. After the reaction is complete, concentrate under reduced pressure until no liquid distills off; add 400 kg of ethyl acetate, adjust the frequency converter to 50 Hz, and slurry for 2 hours. Centrifuge and dry to obtain 145 kg of H-Ser-OMe. HCl (off-white solid) with a molecular weight of 155.58 and a yield of 97.9%.

[0025] S2. Synthesis of H-Ser(tBu)-OMe: 145 kg of H-Ser-OMe obtained from S1 was synthesized. 870 kg of tert-butyl acetate (which reacts with H-Ser-OMe) was added to HCl. The mass ratio of HCl is 6:1. Adjust the frequency converter to 50Hz. After the material dissolves, add 42kg of magnesium perchlorate (which reacts with H-Ser-OMe). The molar ratio of HCl is 0.2:1), and 610 kg of di-tert-butyl dicarbonate (which reacts with H-Ser-OMe) is added dropwise at a controlled temperature of 15~25℃. The HCl was added in a molar ratio of 3:1. After the addition was complete, the temperature was controlled at 15-25℃ for reaction. After the reaction was complete (reaction time was 4 hours), the pH of the system was adjusted to 8 with a 20% potassium carbonate aqueous solution. The mixture was allowed to stand and separated. The aqueous layer was discarded, and the organic phase was concentrated under reduced pressure until no liquid distilled off, yielding 163 kg of H-Ser(tBu)-OMe (a light yellow oily substance) with a molecular weight of 175.23 and a yield of 100%.

[0026] S3. Synthesis of H-Ser(tBu)-OH: Add 150 kg of 30% sodium hydroxide aqueous solution [molar ratio of sodium hydroxide to H-Ser(tBu)-OMe is 1.2:1] to 163 kg of H-Ser(tBu)-OMe obtained in S2. Adjust the frequency converter to 50 Hz and control the temperature at 15~25℃. After the reaction is complete, adjust the pH of the system to 6 with 20% citric acid aqueous solution. Then add 500 kg of ethyl acetate, let stand and separate the layers. Discard the aqueous layer to obtain 150 kg of ethyl acetate solution of H-Ser(tBu)-OH (molecular weight 161.2), with a yield of 100%.

[0027] S4. Synthesis of crude Fmoc-Ser(tBu)-OH: Add 500 kg of water and 154 kg of potassium carbonate to the ethyl acetate solution of 150 kg H-Ser(tBu)-OH obtained in S3. Adjust the frequency converter to 50 Hz and control the temperature at 15~20℃. Add 314 kg of Fmoc-OSu in batches. After the addition is complete, control the temperature at 15~20℃ for reaction. After the reaction is complete, adjust the pH of the system to 3 with a 20% citric acid aqueous solution. Let it stand and separate the layers. Discard the aqueous layer and collect the organic layer. Wash it repeatedly with a 20% sodium chloride aqueous solution until the pH is 6. Add 25 kg of anhydrous sodium sulfate to dry it. Concentrate under reduced pressure until no liquid distills off. Add 300 kg of petroleum ether and stir for 2 h. After centrifugation, obtain 298 kg of crude Fmoc-Ser(tBu)-OH (dry weight).

[0028] S5. Refining crude Fmoc-Ser(tBu)-OH: Add 596 kg of methanol to 298 kg of crude Fmoc-Ser(tBu)-OH obtained in S4, and adjust the frequency converter to 50 Hz; heat to dissolve, and then add 1788 kg of water (methanol to water mass ratio of 1:3). After the addition is complete, control the temperature at 15~25℃, centrifuge, and dry to obtain 283 kg of finished product Fmoc-Ser(tBu)-OH (white solid), with a molecular weight of 383.44, a total yield of 77.6%, a purity of 99.7%, and a maximum single impurity of 0.04%.

[0029] Example 2 This embodiment provides an efficient method for preparing high-purity Fmoc-Ser(tBu)-OH, the steps of which are as follows: S1. Synthesis of H-Ser-OMe HCl: Add 1000 kg of methanol to 100 kg of Ser, adjust the frequency converter to 50 Hz, and add 170 kg of thionyl chloride dropwise while controlling the temperature at 10-20 °C. After the addition is complete, raise the temperature to 50-60 °C and react. After the reaction is complete, concentrate under reduced pressure until no liquid distills off. Add 400 kg of ethyl acetate, adjust the frequency converter to 50 Hz, and slurry for 2 hours. Centrifuge and dry to obtain 147 kg of H-Ser-OMe. HCl (off-white solid) with a molecular weight of 155.58 and a yield of 99.3%.

[0030] S2. Synthesis of H-Ser(tBu)-OMe: 147 kg of H-Ser-OMe obtained from S1 735 kg of tert-butyl ester (which reacts with H-Ser-OMe) was added to HCl. The mass ratio of HCl is 5:1. Adjust the frequency converter to 50Hz. After the material dissolves, add 34 kg of calcium perchlorate (which reacts with H-Ser-OMe). The molar ratio of HCl is 0.15:1. 722 kg of di-tert-butyl dicarbonate (which reacts with H-Ser-OMe) is added dropwise at a controlled temperature of 18-22℃. The molar ratio of HCl was 3.5:1; after addition, the temperature was controlled at 18-22℃ for reaction; after the reaction was complete (reaction time was 5h), the pH of the system was adjusted to 8 with a 20% potassium carbonate aqueous solution, the mixture was allowed to stand and separated, the aqueous layer was discarded, and the organic phase was concentrated under reduced pressure until no liquid distilled off, yielding 166kg of H-Ser(tBu)-OMe (light yellow oily substance) with a molecular weight of 175.23 and a yield of 100%.

[0031] S3. Synthesis of H-Ser(tBu)-OH: Add 210 kg of 30% potassium hydroxide aqueous solution [the molar ratio of potassium hydroxide to H-Ser(tBu)-OMe is 1.2:1] to 166 kg of H-Ser(tBu)-OMe obtained in S2. Adjust the frequency converter to 50 Hz and control the temperature at 15~20℃. After the reaction is complete, adjust the pH of the system to 6 with 20% citric acid aqueous solution. Then add 500 kg of ethyl acetate, let stand and separate the layers. Discard the aqueous layer to obtain 153 kg of ethyl acetate solution of H-Ser(tBu)-OH (molecular weight 161.2), with a yield of 100%.

[0032] S4. Synthesis of crude Fmoc-Ser(tBu)-OH: Add 500 kg of water and 157 kg of potassium carbonate to the ethyl acetate solution of 153 kg H-Ser(tBu)-OH obtained in S3. Adjust the frequency converter to 50 Hz and control the temperature at 20-25℃. Add 320 kg of Fmoc-OSu in batches. After the addition is complete, control the temperature at 20-25℃ for the reaction. After the reaction is complete, adjust the pH of the system to 3 with a 20% citric acid aqueous solution. Let it stand and separate the layers. Discard the aqueous layer and collect the organic layer. Wash it repeatedly with a 20% sodium chloride aqueous solution until the pH is 6. Add 25 kg of anhydrous sodium sulfate to dry it. Concentrate under reduced pressure until no liquid distills off. Add 300 kg of petroleum ether and stir for 2 h. After centrifugation, obtain 304 kg of crude Fmoc-Ser(tBu)-OH (dry weight).

[0033] S5. Refining crude Fmoc-Ser(tBu)-OH: Add 456 kg of acetone to 304 kg of crude Fmoc-Ser(tBu)-OH obtained in S4, and adjust the frequency converter to 50 Hz; heat until dissolved, then add 1824 kg of water dropwise. After the addition is complete, control the temperature at 15~25℃, centrifuge, and dry to obtain 294 kg of finished product Fmoc-Ser(tBu)-OH (white solid), with a molecular weight of 383.44, a total yield of 80.6%, a purity of 99.6%, and a maximum single impurity of 0.03%.

[0034] Example 3 This embodiment provides an efficient method for preparing high-purity Fmoc-Ser(tBu)-OH, the steps of which are as follows: S1. Synthesis of H-Ser-OMe HCl: Add 1000 kg of methanol to 100 kg of Ser, and adjust the frequency converter to 50 Hz; add 170 kg of thionyl chloride dropwise while controlling the temperature at 10-20 °C; after the addition is complete, raise the temperature to 50-60 °C and react. After the reaction is complete, concentrate under reduced pressure until no liquid distills off; add 400 kg of ethyl acetate, adjust the frequency converter to 50 Hz, and slurry for 2 hours. Centrifuge and dry to obtain 144 kg of H-Ser-OMe. HCl (off-white solid) with a molecular weight of 155.58 and a yield of 97.3%.

[0035] S2. Synthesis of H-Ser(tBu)-OMe: 144 kg of H-Ser-OMe obtained from S1 was used to synthesize H-Ser(tBu)-OMe. 864 kg of tert-butyl acetate (which reacts with H-Ser-OMe) was added to HCl. The mass ratio of HCl is 6:1. Adjust the frequency converter to 50Hz. After the material dissolves, add 31kg of barium perchlorate (which reacts with H-Ser-OMe). (The molar ratio of HCl is 0.1:1) 646 kg of di-tert-butyl dicarbonate (which reacts with H-Ser-OMe) is added dropwise at a controlled temperature of 15-20℃. After adding HCl (molar ratio 3.2:1), the temperature was controlled at 15-20℃ for reaction. After the reaction was complete (reaction time was 5 hours), the pH of the system was adjusted to 8 with a 20% potassium carbonate aqueous solution. The mixture was allowed to stand and separated. The aqueous layer was discarded, and the organic phase was concentrated under reduced pressure until no liquid distilled off, yielding 162 kg of H-Ser(tBu)-OMe (light yellow oily substance) with a molecular weight of 175.23 and a yield of 100%.

[0036] S3. Synthesis of H-Ser(tBu)-OH: 173g of a 30% sodium hydroxide aqueous solution [molar ratio of sodium hydroxide to H-Ser(tBu)-OMe is 1.4:1] was added to 162kg of H-Ser(tBu)-OMe obtained in S2. The frequency converter was adjusted to 50Hz and the temperature was controlled at 15~18℃. After the reaction was complete, the pH of the system was adjusted to 6 with a 20% citric acid aqueous solution. Then 500kg of ethyl acetate was added, and the mixture was allowed to stand and separated. The aqueous layer was discarded to obtain 149kg of an ethyl acetate solution of H-Ser(tBu)-OH (molecular weight 161.2), with a yield of 100%.

[0037] S4. Synthesis of crude Fmoc-Ser(tBu)-OH: Add 500 kg of water and 153 kg of potassium carbonate to the ethyl acetate solution of 149 kg H-Ser(tBu)-OH obtained in S3. Adjust the frequency converter to 50 Hz and control the temperature at 15-20℃. Add 320 kg of Fmoc-OSu in batches. After the addition is complete, control the temperature at 15-20℃ for reaction. After the reaction is complete, adjust the pH of the system to 3 with a 20% citric acid aqueous solution. Let it stand and separate the layers. Discard the aqueous layer and collect the organic layer. Wash it repeatedly with a 20% sodium chloride aqueous solution until the pH is 6. Add 25 kg of anhydrous sodium sulfate to dry it. Concentrate under reduced pressure until no liquid distills off. Add 300 kg of petroleum ether and stir for 2 h. After centrifugation, obtain 293 kg of crude Fmoc-Ser(tBu)-OH (dry weight).

[0038] S5. Refining crude Fmoc-Ser(tBu)-OH: Add 586 kg of ethanol to 293 kg of crude Fmoc-Ser(tBu)-OH obtained in S4, adjust the frequency converter to 50 Hz, heat to dissolve, and then add 1758 kg of water dropwise. After the addition is complete, control the temperature at 15~25℃, centrifuge, and dry to obtain 285 kg of finished product Fmoc-Ser(tBu)-OH (white solid). Its molecular weight is 383.44, the total yield is 78.1%, the purity is 99.8%, and the maximum single impurity is 0.01%.

[0039] Comparative Example 1 This comparative example provides a mainstream industrial method for preparing Fmoc-Ser(tBu)-OH, with the following steps: S1. Synthesis of H-Ser-OMe HCl: Process parameters are the same as in Example 2, yielding 147 kg of H-Ser-OMe. HCl (off-white solid) with a molecular weight of 155.58 and a yield of 99.3%.

[0040] S2. Synthesis of H-Ser(tBu)-OH: 147 kg of H-Ser-OMe obtained from S1 was converted into H-Ser(tBu)-OH. Add 1200 kg of dichloromethane to HCl, adjust the frequency converter to 50 Hz, and add 147 kg of H-Ser-OMe. Add HCl, then add 100 kg of sulfuric acid; after the addition is complete, control the temperature at 0~5℃ and pass in 120 kg of isobutylene; after the passage is complete, slowly raise the temperature to 10~20℃; after the reaction is complete (reaction time is 24 h), control the temperature at 10~20℃ and add 500 kg of 30% sodium hydroxide aqueous solution dropwise; after the addition is complete, continue stirring the reaction for 2 h, let it stand to separate into layers, and collect the aqueous layer.

[0041] S3. Synthesis of Fmoc-Ser(tBu)-OH: 800 kg of ethyl acetate was added to the aqueous layer collected in S2, stirring was started, and sodium carbonate aqueous solution was added dropwise to adjust the pH of the system to 8; Fmoc-OSu was then added until the reaction was complete; hydrochloric acid was added dropwise to adjust the pH of the system to 4, and the layers were allowed to stand and separate. The organic layer was collected, and the aqueous layer was extracted twice with 800 kg of ethyl acetate. The organic layers were combined; 20% sodium chloride aqueous solution was added to the combined organic layer to adjust the pH of the system to 6, and the mixture was stirred thoroughly and allowed to stand. The aqueous phase was discarded, and the organic phase was retained; the organic phase was concentrated under reduced pressure until solid precipitated, and then 500 kg of petroleum ether was added and stirred to crystallize. The solid was collected by centrifugation and dried to obtain 248 kg of Fmoc-Ser(tBu)-OH with a molecular weight of 383.44, an overall yield of 68.0%, a purity of 99.7%, and a maximum single impurity of 0.05%.

[0042] Experimental results: Compared with Example 1, Comparative Example 1 requires the use of gaseous material isobutylene, which is flammable and explosive, posing certain safety risks. Furthermore, it places higher demands on the airtightness and pressure resistance of the reaction equipment during the reaction process, extending the preparation cycle by about 1 / 3 and significantly reducing the overall yield (77.6% in Example 1 → 68.0% in Comparative Example 1).

[0043] Comparative Example 2 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH. Except for adjusting the catalyst magnesium perchlorate in S2 to sulfuric acid (concentration of 98%), the other process parameters are the same as in Example 1.

[0044] Experimental results: Compared with Example 1, both the conversion rate of the intermediate and the total yield were significantly reduced. After repeated experiments, the conversion rate was stabilized at around 50% and the total yield was stabilized at 25%~35%.

[0045] Comparative Example 3 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that the solvent tert-butyl acetate in S2 is changed to ethyl acetate, and the other process parameters are the same as in Example 1.

[0046] Experimental results: After multiple experiments, it was found that compared with Example 1, the finished product Fmoc-Ser(tBu)-OH had a higher impurity content, which could not be removed by conventional purification methods, and thus a qualified product could not be obtained.

[0047] Comparative Example 4 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that the solvent tert-butyl acetate in S2 is changed to isopropyl acetate, and the other process parameters are the same as in Example 1.

[0048] Experimental results: After multiple experiments, it was found that compared with Example 1, the finished product Fmoc-Ser(tBu)-OH had a higher impurity content, which could not be removed by conventional purification methods, and thus a qualified product could not be obtained.

[0049] Comparative Example 5 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that magnesium perchlorate in S2 is reacted with H-Ser-OMe Except for adjusting the molar ratio of HCl from 0.2:1 to 0.05:1, the other process parameters are the same as in Example 1.

[0050] Experimental results: H-Ser-OMe was monitored using TLC. The reaction with HCl is essentially complete, but the product is not H-Ser(tBu)-OMe.

[0051] Comparative Example 6 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that magnesium perchlorate in S2 is reacted with H-Ser-OMe Except for adjusting the molar ratio of HCl from 0.2:1 to 0.8:1, the other process parameters are the same as in Example 1.

[0052] Experimental results: H-Ser-OMe was monitored using TLC. The HCl reaction was complete, yielding 288 kg of the final product, Fmoc-Ser(tBu)-OH (white solid), with an overall yield of 78.9%, a purity of 99.6%, and a maximum single impurity of 0.03%. The overall yield, purity, and maximum single impurity were essentially consistent with those of Example 1.

[0053] Comparative Example 7 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that di-tert-butyl dicarbonate in S2 is reacted with H-Ser-OMe Except for adjusting the molar ratio of HCl from 3:1 to 1:1, the other process parameters are the same as in Example 1.

[0054] Experimental results: TLC monitoring after 24 hours of reaction showed H-Ser-OMe The HCl reaction was not complete. After post-processing, 177 kg of the finished product Fmoc-Ser(tBu)-OH was obtained, with an overall yield of 48.5%, which was significantly lower than that in Example 1.

[0055] Comparative Example 8 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that di-tert-butyl dicarbonate in S2 is reacted with H-Ser-OMe Except for adjusting the molar ratio of HCl from 3:1 to 8:1, the other process parameters are the same as in Example 1.

[0056] Experimental results: H-Ser-OMe was monitored using TLC. The HCl reaction was complete, yielding 282 kg of the finished product Fmoc-Ser(tBu)-OH (white solid). The overall yield was 77.3%, the purity was 99.6%, and the maximum single impurity was 0.04%. The overall yield, purity, and maximum single impurity were basically consistent with those of Example 1.

[0057] Comparative Example 9 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that tert-butyl acetate in S2 is reacted with H-Ser-OMe Except for adjusting the mass ratio of HCl from 6:1 to 4:1, the rest of the process is the same as in Example 1.

[0058] Experimental results: The reaction system was turbid, and the reaction changed from a homogeneous to a heterogeneous reaction, leading to H-Ser-OMe The HCl conversion rate was significantly lower than that in Example 1.

[0059] Comparative Example 10 This comparative example provides a method for preparing Fmoc-Ser(tBu)-OH, except that tert-butyl acetate in S2 is reacted with H-Ser-OMe Except for adjusting the mass ratio of HCl from 6:1 to 12:1, the rest of the process is the same as in Example 1.

[0060] Experimental results: The overall yield, purity, and maximum single impurity were basically consistent with those of Example 1.

[0061] In summary, compared with the mainstream industrial preparation method (Comparative Example 1), the present invention has lower safety risks because it does not use gaseous materials, and the requirements for the airtightness and pressure resistance of the equipment during the reaction process are lower, the preparation cycle is shortened by about 1 / 4, and the overall yield is significantly improved. Meanwhile, in this invention, perchlorate, tert-butyl acetate, and di-tert-butyl dicarbonate have a synergistic effect within a specific ratio range: using only tert-butyl acetate and di-tert-butyl dicarbonate (Comparative Example 2), or only perchlorate and di-tert-butyl dicarbonate (Comparative Examples 3 and 4), the quality of the resulting product is not as good as when all three are used together (Example 1); when the amount of perchlorate is too low (Comparative Example 5), the target product cannot be synthesized effectively, while when the amount is too high (Comparative Example 6), although the purity and single impurity of the product are comparable to those of this invention (Example 1), the material consumption increases; when the amount of di-tert-butyl dicarbonate is insufficient (Comparative Example 7), the total yield of the product decreases significantly, while when the amount is too high (Comparative Example 8), it also causes material waste; when the amount of tert-butyl acetate (Comparative Example 9) is too low, H-Ser-OMe The HCl conversion rate decreased significantly, which in turn led to a decrease in the total yield of the finished product. When the dosage was too high (Comparative Example 10), although the quality of the finished product was comparable to that of the present invention (Example 1), the material consumption increased.

[0062] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A highly efficient method for preparing high-purity Fmoc-Ser(tBu)-OH, characterized in that, Includes the following steps: After mixing Ser and methanol thoroughly, thionyl chloride is added dropwise to react and yield H-Ser-OMe. HCl; The H-Ser-OMe After HCl is dissolved in tert-butyl acetate, it reacts with ditert-butyl dicarbonate in the presence of perchlorate to give H-Ser(tBu)-OMe; The H-Ser(tBu)-OMe was hydrolyzed to obtain H-Ser(tBu)-OH; The H-Ser(tBu)-OH was reacted with Fmoc-OSu to obtain Fmoc-Ser(tBu)-OH. The tert-butyl acetate and the H-Ser-OMe The mass ratio of HCl is (5~10):1; the perchlorate and the H-Ser-OMe The molar ratio of HCl is (0.1~0.5):1; the ditert-butyl dicarbonate and the H-Ser-OMe The molar ratio of HCl is (2~6):

1.

2. The efficient preparation method for high-purity Fmoc-Ser(tBu)-OH according to claim 1, characterized in that, The perchlorate is one or more of magnesium perchlorate, zinc perchlorate, calcium perchlorate, strontium perchlorate, or barium perchlorate.

3. The efficient preparation method for high-purity Fmoc-Ser(tBu)-OH according to claim 1, characterized in that, The tert-butyl acetate and the H-Ser-OMe The mass ratio of HCl is (5~8):

1.

4. The efficient preparation method for high-purity Fmoc-Ser(tBu)-OH according to claim 1, characterized in that, The perchlorate and the H-Ser-OMe The molar ratio of HCl is (0.1~0.3):

1.

5. The efficient preparation method of high-purity Fmoc-Ser(tBu)-OH according to claim 1, characterized in that, The ditert-butyl dicarbonate and the H-Ser-OMe The molar ratio of HCl is (3~4):

1.

6. The efficient preparation method for high-purity Fmoc-Ser(tBu)-OH according to claim 1, characterized in that, The H-Ser(tBu)-OMe is hydrolyzed under alkaline conditions to give H-Ser(tBu)-OH, wherein the alkaline conditions are an aqueous solution of alkali metal hydroxide.

7. The efficient preparation method for high-purity Fmoc-Ser(tBu)-OH according to claim 6, characterized in that, The alkali metal hydroxide is one or both of sodium hydroxide and potassium hydroxide.

8. The efficient preparation method of high-purity Fmoc-Ser(tBu)-OH according to claim 6, characterized in that, The molar ratio of the alkali metal hydroxide to the H-Ser(tBu)-OMe is (1.2~2.5):

1.

9. The efficient preparation method for high-purity Fmoc-Ser(tBu)-OH according to claim 1, characterized in that, After obtaining the Fmoc-Ser(tBu)-OH, it is purified in a mixture of organic solvent and water.

10. The efficient preparation method of high-purity Fmoc-Ser(tBu)-OH according to claim 9, characterized in that, The mass ratio of the organic solvent to the water is 1:(1~5).

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