Method for efficiently preparing Fmoc-Dap-OH

Abstract

The invention discloses a method for efficiently preparing Fmoc-Dap-OH, which comprises the following steps: A, taking L-asparagine as a starting material, and reacting with 9-fluorenyl methyl-N-succinimido carbonate to obtain solid powder Fmoc-Asn-OH; and B, uniformly mixing the solid powder Fmoc-Asn-OH and the solid powder iodobenzene diacetic acid according to a ratio, then adding the mixture into a second mixed solvent formed by mixing an ether solvent and water in a manner of stirring while adding, and after the reaction is finished, obtaining the solid powder Fmoc-Asn-OH / iodobenzene diacetic acid, wherein the ether solvent is selected from one or more of tetrahydrofuran, ethylene glycol dimethyl ether and methyl tetrahydrofuran. According to the present invention, the test research results show that the reaction efficiency is substantially improved by combining the special feeding mode with the adaptive solvent system under the condition of ensuring the yield, the reaction can be completed in a short time, the target product can be obtained, the method is suitable for industrial production, and the technical defects of the existing method are overcome.

Description

Technical Field

[0001] The invention relates to the technical field of pharmaceutical intermediate preparation, and in particular to a method for efficiently preparing Fmoc-Dap-OH. Background Art

[0002] Fmoc-Dap-OH is a protected amino acid, an organic synthesis intermediate and a pharmaceutical intermediate. It can be used in biochemical research, organic synthesis and pharmaceutical research and development. It can also be used as a starting material for preparing other protected amino acids, such as Fmoc-Dap(Boc)-OH, Fmoc-Dap(Mtt)-OH, etc. Its structural formula is shown below:

[0003]

[0004] The synthesis method reported in the literature is generally the following route: L-asparagine (L-Asn) reacts with Fmoc-OSu to obtain the intermediate Fmoc-Asn-OH, and Fmoc-Asn-OH undergoes Hofmann degradation reaction with iodophenyl diacetic acid to generate the target product Fmoc-Dap-OH. In the industrial production of Fmoc-Asn-OH, the mainstream method adopts the reaction of L-asparagine (L-Asn) with 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu), and the reaction conditions are slightly different; in the second step reaction, Lin-hua Zhang, Goss S. Kauffman and others have reported that the solvent uses a mixture of acetonitrile, ethyl acetate and water, and the solvent ratio is slightly different. However, we have found in practice that the reaction time of the solvent with the above ratio is often long, and even the situation that the reaction cannot be completely completed occurs, which is not suitable for industrial production. In addition, the above mainstream method will produce wastewater / waste liquid containing acetonitrile, and the treatment cost is high, which is not a preferred technical solution. Summary of the invention

[0005] The purpose of the present invention is to provide a simple, efficient and environmentally friendly method for preparing Fmoc-Dap-OH in view of the above-mentioned problems. The present invention summarizes through experimental research and finds that the special feeding method combined with the adapted solvent system not only does not significantly reduce the product yield, but also greatly improves the reaction efficiency, which is very suitable for industrial production and overcomes the shortcomings of the existing process.

[0006] The technical solution adopted by the present invention is as follows: A method for preparing Fmoc-Dap-OH with high efficiency comprises the following steps:

[0007] A. Using L-asparagine (L-Asn) as the starting material, react with 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) to obtain solid powder Fmoc-Asn-OH;

[0008] B. Mix solid powder Fmoc-Asn-OH and solid powder iodophenyldiacetic acid (PIDA) in proportion, and then add the mixture into a second mixed solvent of an ether solvent and water while stirring, and obtain the product after the reaction is completed; wherein the ether solvent is selected from one or more of tetrahydrofuran, ethylene glycol dimethyl ether, and methyltetrahydrofuran.

[0009] In the above preparation method, the chemical reaction formula involved is as follows:

[0010]

[0011] Furthermore, the mass ratio of Fmoc-Asn-OH to iodophenyldiacetic acid is 1:1-1.2, for example, it can be 1:1, 1:1.05, 1:1.08, 1:1.1, 1:1.15, 1:1.2, etc.

[0012] Furthermore, the volume mass ratio of the ether solvent to Fmoc-Asn-OH is 4-6:1, for example, 4:1, 4.5:1, 4.8:1, 5:1, 5.5:1, 6:1, etc.

[0013] Furthermore, in the second mixed solvent, the volume ratio of the ether solvent to water is 1:0.3-1, for example, it can be 1:0.3, 1:0.5, 1:0.6, 1:0.8, 1:1, etc.

[0014] Furthermore, in step B, when the mixed powder of Fmoc-Asn-OH and iodophenyldiacetic acid is added to the second mixed solvent, the adding speed is 0.5-2 kg / min, for example, 0.5 kg / min, 1 kg / min, 1.5 kg / min, 2 kg / min, etc.

[0015] Further, in step B, the reaction temperature is controlled within the range of 20-30°C.

[0016] Further, in step A, L-asparagine and an inorganic base are first added to a first mixed solvent of an organic solvent and water to dissolve completely, and then 9-fluorenylmethyl-N-succinimidyl carbonate is added to react, and Fmoc-Asn-OH is obtained after the reaction is completed; wherein the organic solvent is selected from one of acetone, ethyl acetate, and methyltetrahydrofuran.

[0017] Furthermore, the volume mass ratio of the organic solvent to L-asparagine in the first mixed solvent is 2-4:1 (for example, it can be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc.), and the volume ratio of the organic solvent to water is 1:2.5-4, for example, it can be 1:2.5, 1:2.8, 1:3, 1:3.5, 1:3.8, 1:4, etc.

[0018] Furthermore, the mass ratio of L-asparagine to 9-fluorenylmethyl-N-succinimidyl carbonate is 1:2-3.5, for example, 1:2, 1:2.5, 1:2.6, 1:2.8, 1:3, 1:3.5, etc.

[0019] Furthermore, the mass ratio of the inorganic base to L-asparagine is 1.5-2.5:1, for example, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, etc. The inorganic base of the present invention is not particularly limited, and common sodium carbonate, potassium carbonate, etc. can be used.

[0020] In summary, due to the adoption of the above technical scheme, the beneficial effect of the present invention is as follows: the present invention has found through experimental research that a special feeding method is combined with an adapted solvent system (solid powder Fmoc-Asn-OH and solid powder iodophenyl diacetic acid are mixed uniformly in proportion, and then added to a second mixed solvent of an ether solvent and water while stirring, and the ether solvent is selected from one or more of tetrahydrofuran, ethylene glycol dimethyl ether, and methyltetrahydrofuran), while ensuring the yield, the reaction efficiency is greatly improved, the reaction can be completed in a short time and the target product can be obtained, the method is not only suitable for industrial production, but also the organic solvent used is more environmentally friendly than the existing mainstream method, reduces the waste liquid treatment cost, and overcomes the technical defects of the existing method. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The following terms or definitions are provided merely to aid understanding of the present invention. These definitions should not be construed as having a scope less than that understood by those skilled in the art.

[0023] Unless defined otherwise hereinafter, the meaning of all technical terms and scientific terms used in the specific embodiments of the present invention are intended to be the same as those generally understood by those skilled in the art. Although it is believed that the following terms are well understood by those skilled in the art, the following definitions are still set forth to better explain the present invention.

[0024] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0025] Example 1

[0026] (1) Preparation of Fmoc-Asn-OH:

[0027] To a 500L glass-lined reactor, 264kg of water, 80kg of acetone, 26.4kg of L-asparagine (molecular weight 132.12), and 42.4kg of sodium carbonate (molecular weight 105.99) were added. After stirring until completely dissolved, 63kg of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) (molecular weight 337.33) was added in batches. The temperature was controlled at 20-30°C for reaction. The reaction of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) was completed by TLC monitoring. After post-treatment, 60kg of white solid powder (Fmoc-Dap-OH, molecular weight 354.36) was obtained, with a yield of 90.7%.

[0028] (2) Preparation of Fmoc-Dap-OH:

[0029] S1, grind and mix 60 kg of Fmoc-Dap-OH solid powder and 65.4 kg of solid powder of iodophenyl diacetic acid (molecular weight 322.1) to obtain a mixed powder;

[0030] S2. Add 216 kg (240 L) of tetrahydrofuran and 120 kg of water into a 500 L glass-lined reactor, stir and mix to obtain a mixed solvent, then add the mixed powder to the mixed solvent at a rate of 1.0 kg / min, add the materials while stirring, the stirring speed is 50 Hz, and the temperature is controlled at 20-30 ° C. After the reaction is completed for 2 h, 36 kg of off-white solid (Fmoc-Dap-OH, molecular weight 326.35) is obtained after post-treatment, with a yield of 65.1% and a purity of 99.5% detected by HPLC.

[0031] Example 2

[0032] (1) Preparation of Fmoc-Asn-OH:

[0033] To a 500L glass-lined reactor, 240kg of water, 80kg of methyltetrahydrofuran, 26.4kg of L-asparagine (molecular weight 132.12), and 42.4kg of sodium carbonate (molecular weight 105.99) were added. After stirring until completely dissolved, 63kg of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) (molecular weight 337.33) was added in batches. The temperature was controlled at 20-30°C for reaction. The reaction of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) was completed by TLC monitoring. After post-treatment, 58kg of white solid powder (Fmoc-Dap-OH, molecular weight 354.36) was obtained, with a yield of 87.6%.

[0034] (2) Preparation of Fmoc-Dap-OH:

[0035] S1, grind and mix 58 kg of Fmoc-Dap-OH solid powder and 63.3 kg of solid powder of iodophenyl diacetic acid (molecular weight 322.1) to obtain a mixed powder;

[0036] S2. Add 210 kg (240 L) of ethylene glycol dimethyl ether and 116 kg of water into a 500 L glass-lined reactor, stir and mix to obtain a mixed solvent, then add the mixed powder to the mixed solvent at a rate of 1.0 kg / min, add the materials while stirring, the stirring speed is 50 Hz, and the temperature is controlled at 20-30 ° C. After the reaction is completed for 2 h, 35 kg of off-white solid (Fmoc-Dap-OH, molecular weight 326.35) is obtained after post-treatment, with a yield of 65.5% and a purity of 99.4% detected by HPLC.

[0037] Example 3

[0038] (1) Preparation of Fmoc-Asn-OH:

[0039] To a 500L glass-lined reactor, 270kg of water, 80kg of ethyl acetate, 26.4kg of L-asparagine (molecular weight 132.12), and 55.3kg of potassium carbonate (molecular weight 105.99) were added. After stirring until completely dissolved, 63kg of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) (molecular weight 337.33) was added in batches. The temperature was controlled at 20-30°C for reaction. The reaction of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) was completed by TLC monitoring. After post-treatment, 58kg of white solid powder (Fmoc-Dap-OH, molecular weight 354.36) was obtained, with a yield of 87.6%.

[0040] (2) Preparation of Fmoc-Dap-OH:

[0041] S1, grind and mix 58 kg of Fmoc-Dap-OH solid powder and 63.3 kg of solid powder of iodophenyl diacetic acid (molecular weight 322.1) to obtain a mixed powder;

[0042] S2. Add 216 kg of tetrahydrofuran and 120 kg of water into a 500 L glass-lined reactor, stir and mix to obtain a mixed solvent, then add the mixed powder into the mixed solvent at a rate of 1.2 kg / min, add the materials while stirring, the stirring speed is 50 Hz, and the temperature is controlled at 20-30 ° C. After the reaction is completed for 2 h, 37 kg of off-white solid (Fmoc-Dap-OH, molecular weight 326.35) is obtained after post-treatment, with a yield of 69.3% and a purity of 99.5% detected by HPLC.

[0043] Comparative Example 1

[0044] This comparative example was prepared according to the existing literature method.

[0045] (1) Preparation of Fmoc-Asn-OH:

[0046] To a 500L glass-lined reactor, 264kg of water, 80kg of methyltetrahydrofuran, 26.4kg of L-asparagine (molecular weight 132.12), and 42.4kg of sodium carbonate (molecular weight 105.99) were added. After stirring until completely dissolved, 63kg of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) (molecular weight 337.33) was added in batches. The temperature was controlled at 20-30°C for reaction. The reaction of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) was completed by TLC monitoring. After post-treatment, 61kg of white solid (Fmoc-Asn-OH, molecular weight 354.36) was obtained, with a yield of 92.2%.

[0047] (2) Preparation of Fmoc-Dap-OH:

[0048] To a 500L glass-lined reactor, 192kg of acetonitrile, 216kg of ethyl acetate, 120kg of water, and 61kg of Fmoc-Asn-OH were added, and after mixing, 65.4kg of iodophenyldiacetic acid (molecular weight 322.1) was added. After the addition was completed, the temperature was controlled at 20-30°C for reaction. After 48h of reaction, the reaction was still not complete (TLC detection found that the conversion rate was <50%).

[0049] Comparative Example 2

[0050] This comparative example was prepared according to the existing literature method.

[0051] (1) Preparation of Fmoc-Asn-OH:

[0052] To a 500L glass-lined reactor, 264kg of water, 80kg of methyltetrahydrofuran, 26.4kg of L-asparagine (molecular weight 132.12), and 42.4kg of sodium carbonate (molecular weight 105.99) were added. After stirring until completely dissolved, 63kg of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) (molecular weight 337.33) was added in batches. The temperature was controlled at 20-30°C for reaction. The reaction of 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) was completed by TLC monitoring. After post-treatment, 61kg of white solid (Fmoc-Asn-OH, molecular weight 354.36) was obtained, with a yield of 92.2%.

[0053] (2) Preparation of Fmoc-Dap-OH:

[0054] To a 500L glass-lined reactor, 288kg of acetonitrile, 324kg of ethyl acetate, 180kg of water, and 61kg of Fmoc-Asn-OH were added, and after mixing, 65.4kg of iodophenyldiacetic acid (molecular weight 322.1) was added. After the addition was completed, the temperature was controlled at 20-30°C for reaction. After 48h of reaction, the reaction was still not complete (TLC detection found that the conversion rate was <50%).

[0055] Comparative Example 3

[0056] Using 60 kg of white solid powder (Fmoc-Dap-OH, molecular weight 354.36) prepared in Example 1 as a raw material, 216 kg (240 L) of tetrahydrofuran, 60 kg of Fmoc-Dap-OH and 120 kg of water were added to a 500 L glass-lined reactor and stirred to obtain a mixed solution, and then 65.4 kg of iodophenyl diacetic acid (molecular weight 322.1) was added. After the addition was completed, the temperature was controlled at 20-30 ° C. The reaction was completed after 20 hours of reaction, and 33 kg of off-white solid was obtained after post-treatment. The yield: 60.0%.

[0057] Comparative Example 4

[0058] S1, using 60 kg of the white solid powder (Fmoc-Dap-OH, molecular weight 354.36) prepared in Example 1 as a raw material, and 65.4 kg of solid powder iodophenyl diacetic acid (molecular weight 322.1), grinding and mixing to obtain a mixed powder;

[0059] S2. Add 288 kg of acetonitrile, 324 kg of ethyl acetate and 180 kg of water into a 500 L glass-lined reactor and stir to obtain a mixed solvent. Then add the mixed powder to the mixed solvent at a rate of 1.0 kg / min while stirring. The stirring speed is 50 Hz and the temperature is controlled at 20-30°C. After 48 hours of reaction, the reaction is still not complete (TLC detection shows that the conversion rate is <50%).

[0060] 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 protection scope of the present invention.

Claims

1. A method for efficiently preparing Fmoc-Dap-OH, characterized in that: The steps include: A. Using L-asparagine as the starting material, reacting with 9-fluorenylmethyl-N-succinimidyl carbonate (Fmoc-OSu) to obtain solid powder Fmoc-Asn-OH; B. Mix solid powder Fmoc-Asn-OH and solid powder iodophenyldiacetic acid (PIDA) in proportion, and then add the mixture into a second mixed solvent of an ether solvent and water while stirring, and obtain the product after the reaction is completed; wherein the ether solvent is selected from one or more of tetrahydrofuran, ethylene glycol dimethyl ether, and methyltetrahydrofuran.

2. The method according to claim 1, characterized in that The mass ratio of Fmoc-Asn-OH to iodophenyldiacetic acid is 1:1-1.

2.

3. The method according to claim 2, characterized in that The volume mass ratio of the ether solvent to Fmoc-Asn-OH is 4-6:

1.

4. The method according to claim 3, characterized in that In the second mixed solvent, the volume ratio of the ether solvent to water is 1:0.3-1.

5. The method according to claim 4, characterized in that In step B, when the mixed powder of Fmoc-Asn-OH and iodophenyldiacetic acid is added to the second mixed solvent, the adding speed is 0.5-2 kg / min.

6. The method according to any one of claims 1 to 5, characterized in that: In step B, the reaction temperature is controlled within the range of 20-30°C.

7. The method according to claim 6, characterized in that In step A, L-asparagine and an inorganic base are first added to a first mixed solvent of an organic solvent and water to dissolve completely, and then 9-fluorenylmethyl-N-succinimidyl carbonate is added to react, and Fmoc-Asn-OH is obtained after the reaction is completed; wherein the organic solvent is selected from one of acetone, ethyl acetate, and methyltetrahydrofuran.

8. The method according to claim 7, characterized in that The volume mass ratio of the organic solvent to L-asparagine in the first mixed solvent is 2-4:1, and the volume ratio of the organic solvent to water is 1:2.5-4.

9. The method according to claim 7, characterized in that The mass ratio of L-asparagine to 9-fluorenylmethyl-N-succinimidyl carbonate is 1:2-3.

5.

10. The method according to claim 7, characterized in that The mass ratio of the inorganic base to L-asparagine is 1.5-2.5:1.

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