Preparation of Mal-PEG2-CH2COOH

Abstract

The application belongs to the technical field of organic synthesis, and specifically provides a preparation method of Mal-PEG2-CH2COOH, comprising the following steps: S1, reacting AEEA with maleic anhydride to generate an intermediate, wherein the intermediate is (Z)-2-(2-(N-hydroxyethyl)hydroxyethyl)carboxymethyl)maleic acid monoamide; and S2, performing ring closure reaction on the intermediate to generate Mal-PEG2-CH2COOH. According to the preparation method of the embodiment of the application, the open ring-closure step-by-step synthesis strategy is adopted, so that the harsh reaction condition of high temperature and acid is avoided, the preparation cost is reduced, the overall reaction yield is improved, and the three-waste discharge and environmental pollution are reduced.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and more specifically, relates to a method for preparing Mal-PEG2-CH2COOH. Background Technology

[0002] Antibody-drug conjugates (ADCs) are a novel class of targeted therapies, primarily composed of an antibody, a cytotoxic drug, and a linker between the two. The linker, acting as a bridge between the antibody and the drug, must not only maintain high stability in the bloodstream to prevent premature drug release but also respond to specific conditions (such as pH changes or enzymatic degradation) upon reaching the target site to release the active drug. However, commonly used cytotoxic drugs are mostly hydrophobic molecules, and their binding to antibodies can lead to ADC aggregation, thereby affecting their in vivo performance. Therefore, using hydrophilic linkers to mask or reduce the hydrophobicity of the drug is considered an effective strategy.

[0003] [(2-{[2-(2,5-dioxo-2,5-dihydro-1H-pyrrole-1-yl)ethoxy]ethoxy}]acetic acid (hereinafter referred to as Mal-PEG2-CH2COOH) is a hydrophilic linker that can shield the lipophilicity of drugs and improve the pharmaceutical activity of ADCs. It is often used as a functional research tool in the construction of ADCs.

[0004] Currently, there are few reports on the synthesis methods of Mal-PEG2-CH2COOH. The main method uses AEEA hydrochloride as the starting material, reacting it with maleic anhydride in acetic acid under prolonged heating to generate the target compound, with a yield of 42%. The specific synthetic route is shown in equation (1) below: (1) However, this synthetic route has low yields and requires long-term high-temperature reactions under mixed acid conditions, which places high demands on reaction equipment and causes significant pollution. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing Mal-PEG2-CH2COOH with mild reaction conditions, high reaction efficiency, and green and environmentally friendly process.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The method for preparing Mal-PEG2-CH2COOH according to an embodiment of the present invention includes: Step S1 involves reacting AEEA with maleic anhydride to generate an intermediate, which is (Z)-2-(2-(N-hydroxyethyl)hydroxyethyl)carboxymethyl)maleic acid monoamide. Step S2 involves causing the intermediate to undergo a cyclization reaction to generate Mal-PEG2-CH2COOH.

[0007] In some embodiments of the present invention, in step S1, the reaction is carried out in a first solvent, wherein the first solvent is selected from any one or more of dichloromethane, acetonitrile, acetone, and DMF.

[0008] Furthermore, the molar ratio of AEEA to maleic anhydride is 1:(1.0~1.5).

[0009] Furthermore, in step S1, the reaction temperature is 0~40℃ and the reaction time is 2~8 h.

[0010] Further, in step S1, after the reaction is complete, the reaction solution is concentrated, water is added to precipitate crystals, filtered, slurried with ethyl acetate / n-heptane, and dried to obtain the intermediate.

[0011] In some embodiments of the present invention, in step S2, the cyclization reaction is carried out in a second solvent under the action of a catalyst, wherein the second solvent is selected from any one or more of toluene, xylene, and n-heptane.

[0012] Furthermore, in step S2, the catalyst is selected from any one or more of p-toluenesulfonic acid, concentrated sulfuric acid, and phosphoric acid.

[0013] Furthermore, in step S2, the molar ratio of the intermediate to the catalyst is 1:(0.01~0.4).

[0014] Furthermore, in step S2, the reaction temperature is 80~140℃ and the reaction time is 5~12 h.

[0015] Further, in step S2, after the reaction is complete, the mixture is concentrated under reduced pressure and purified by column chromatography to obtain the Mal-PEG2-CH2COOH.

[0016] The above-described technical solution of the present invention has at least one of the following beneficial effects: The method for preparing Mal-PEG2-CH2COOH according to embodiments of the present invention adopts a ring-opening-ring-closing stepwise synthesis strategy, which not only avoids the harsh reaction conditions of acid and high temperature, reducing the preparation cost, but also improves the overall reaction yield and reduces the emission of waste and environmental pollution. Furthermore, by using conventional organic solvents instead of acidic solvents such as acetic acid in existing methods, the emissions of waste and environmental pollution are reduced. The reaction is also gentle and friendly to equipment, simple to operate, and green and safe. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0018] The preparation method of Mal-PEG2-CH2COOH according to embodiments of the present invention will be described in detail below.

[0019] The method for preparing Mal-PEG2-CH2COOH according to an embodiment of the present invention includes: Step S1 involves reacting AEEA with maleic anhydride to generate an intermediate, which is (Z)-2-(2-(N-hydroxyethyl)hydroxyethyl)carboxymethyl)maleic acid monoamide. Step S2 involves causing the intermediate to undergo a cyclization reaction to generate Mal-PEG2-CH2COOH.

[0020] Specifically, the synthesis route is shown in equation (2) below: (2) In other words, according to the preparation method of the present invention, AEEA (i.e., 2-(2-(2-aminoethoxy)ethoxy)acetic acid as shown in the structural formula of the starting material in formula (2) above) and maleic anhydride are used as starting materials. An intermediate is first generated by ring-opening addition, and then the target product is obtained by dehydration and ring closure. According to the preparation method of the present invention, the ring-opening-ring-closing stepwise synthesis strategy not only avoids the harsh reaction conditions of acidic high temperature, reducing preparation costs, but also improves the overall reaction yield and reduces waste emissions and environmental pollution.

[0021] Below, each step will be explained in detail.

[0022] (1) Step S1, AEEA reacts with maleic anhydride to generate an intermediate.

[0023] In other words, starting with AEEA and maleic anhydride, a ring-opening addition reaction is first carried out to generate the intermediate (Z)-2-(2-(N-hydroxyethyl)hydroxyethyl)carboxymethyl)maleic acid monoamide. This allows the reaction to proceed at a lower temperature, avoiding the self-polymerization side reactions of maleic anhydride at high temperatures, and also requires less sophisticated equipment and is easier to operate.

[0024] According to some embodiments of the present invention, in step S1, the reaction is carried out in a first solvent.

[0025] The first solvent can be selected from any one or more of dichloromethane, acetonitrile, acetone, and DMF. DMF is preferred, as AEEA has the best solubility in DMF, which is beneficial for the reaction and improves the reaction rate and yield.

[0026] In some embodiments of the present invention, the molar ratio of AEEA to maleic anhydride is 1:(1.0~1.5); preferably, the molar ratio of AEEA to maleic anhydride is 1:1.05. That is, using maleic anhydride in slightly higher stoichiometric amounts than AEEA ensures complete reaction of AEEA without wasting raw materials and avoids side reactions caused by excess.

[0027] In addition, the reaction temperature can be 0~40℃, preferably 15~20℃. Too high a temperature can easily cause side reactions, affecting the post-processing effect and the purity of the intermediate.

[0028] The reaction time can be 2 to 8 hours. For example, a reaction can be completed in 5 hours at 15 to 20°C.

[0029] In other words, the reaction temperature of the preparation method of the present invention is controlled at around room temperature, eliminating the need for high temperature, reducing energy consumption and equipment requirements, and the reaction is faster and more efficient.

[0030] In some embodiments of the present invention, in step S1, after the reaction is complete, the reaction solution is concentrated, water is added to induce crystallization, the solution is filtered, slurried with ethyl acetate / n-heptane, and dried to obtain the intermediate. In other words, no complex purification process is required; only conventional crystallization and slurrying operations are needed to obtain a high-purity intermediate, making it suitable for large-scale industrial production.

[0031] (2) Step S2, the intermediate undergoes a cyclization reaction to generate Mal-PEG2-CH2COOH.

[0032] In other words, after obtaining the intermediate, the target product Mal-PEG2-CH2COOH can be obtained by simply causing the intermediate (Z)-2-(2-(N-hydroxyethyl)hydroxyethyl)carboxymethyl)maleic acid monoamide to undergo a cyclization reaction.

[0033] In some embodiments of the present invention, the ring-closing reaction is carried out in a second solvent in the presence of a catalyst.

[0034] The second solvent can be any one or more selected from toluene, xylene, and n-heptane. Toluene is preferred, as it has the best water-carrying effect, which is beneficial to the forward reaction and increases the reaction rate and yield.

[0035] Furthermore, the presence of a catalyst can accelerate the ring-closing reaction. The catalyst used can be selected from any one or more of p-toluenesulfonic acid, concentrated sulfuric acid, and phosphoric acid. Preferably, the catalyst is p-toluenesulfonic acid, which has high catalytic efficiency, requires a small amount, and is convenient and safe to operate.

[0036] In some embodiments of the present invention, the molar ratio of intermediate 1 to catalyst is 1:(0.01~0.4); preferably, the molar ratio of intermediate 1 to catalyst is 1:0.05.

[0037] Furthermore, the reaction temperature can be 80~140℃, preferably 105~110℃. At this temperature, the reaction can proceed fully and efficiently, removing water and accelerating the ring-closing reaction. At low temperatures, the reaction is incomplete, while higher reaction temperatures can increase the reaction rate but also easily lead to side reactions. In addition, excessively high reaction temperatures result in severe solvent evaporation and increased energy consumption.

[0038] The reaction time can be 5 to 12 hours, preferably 8 hours.

[0039] In some embodiments of the present invention, in step S2, after the reaction is completed, the mixture is concentrated under reduced pressure and purified by column chromatography to obtain the Mal-PEG2-CH2COOH.

[0040] As described above, this invention provides a simple and effective method for preparing Mal-PEG2-CH2COOH. Furthermore, the preparation method of this invention is simple to operate, has strong route feasibility, high yield, and is environmentally friendly.

[0041] The preparation method of Mal-PEG2-CH2COOH of the present invention will be further described in detail below through specific embodiments.

[0042] Example 1

[0043] (a) Preparation of intermediates by ring-opening addition reaction Add 250 mL of DMF to a 500 mL three-necked flask, then add 45 g of AEEA. Cool the reaction system to 0-5 °C, add 28.4 g of maleic anhydride in portions, and then heat to 15-20 °C for 5 h.

[0044] Post-processing: The reaction solution was concentrated, and then 250 mL of ice water was added to the residue. After stirring for a while to induce crystallization, the mixture was filtered. The filter cake was washed with a small amount of ice water and then slurried with 300 mL of ethyl acetate / n-heptane (1:5) mixed solvent. After drying, 68.44 g of intermediate was obtained, with a yield of 95.0%.

[0045] (II) Preparation of Mal-PEG2-CH2COOH by cyclization reaction Add 200 mL of toluene to a 500 mL three-necked flask, then add 40 g of intermediate and 1.32 g of p-toluenesulfonic acid in sequence. Heat to 105-110 °C and reflux for 8 h while separating water.

[0046] Post-processing: The reaction solution was concentrated, and the crude product was purified by column chromatography using a dichloromethane / methanol mixed solvent to obtain 33.52 g Mal-PEG2-CH2COOH, with a yield of 90.0%.

[0047] The NMR results of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.27 (s, 1H), 6.71 (s, 2H), 4.13 (s, 2H), 3.76 – 3.62 (m, 8H). The results showed that its structure matched that of the target product Mal-PEG2-CH2COOH.

[0048] Example 2

[0049] (a) Preparation of intermediates by ring-opening addition reaction Add 250 mL of dichloromethane to a 500 mL three-necked flask, then add 45 g of AEEA. Cool the reaction system to 0-5 °C, add 28.4 g of maleic anhydride in portions, and then heat to 15-20 °C and react for 5 h.

[0050] Post-processing: The reaction solution was concentrated, then slurried with 300 mL of ethyl acetate / n-heptane (1:5) mixed solvent, and dried to obtain 54.46 g of intermediate, with a yield of 75.6%.

[0051] (II) Preparation of Mal-PEG2-CH2COOH by cyclization reaction Add 200 mL of n-heptane to a 500 mL three-necked flask, then add 40 g of intermediate and 1.32 g of p-toluenesulfonic acid in sequence. Heat to 105-110 °C and reflux for 8 h while separating water.

[0052] Post-processing: The reaction solution was concentrated, and the crude product was purified by column chromatography using a dichloromethane / methanol mixed solvent to obtain 31.36 g Mal-PEG2-CH2COOH, with a yield of 84.2%.

[0053] The NMR results of the product are as follows: 1H NMR (400 MHz, CDCl3) δ 8.27 (s, 1H), 6.71 (s, 2H), 4.13 (s, 2H), 3.76 – 3.62 (m, 8H). The results showed that its structure matched that of the target product Mal-PEG2-CH2COOH.

[0054] Example 3

[0055] (a) Preparation of intermediates by ring-opening addition reaction Add 250 mL of DMF to a 500 mL three-necked flask, then add 45 g of AEEA. Cool the reaction system to 0-5 °C, and add 32.45 g of maleic anhydride in portions. After the addition is complete, raise the temperature to 15-20 °C and react for 5 h.

[0056] Post-processing: The reaction solution was concentrated, and then 250 mL of ice water was added to the residue. After stirring for a while to induce crystallization, the mixture was filtered. The filter cake was washed with a small amount of ice water and then slurried with 300 mL of ethyl acetate / n-heptane (1:5) mixed solvent. After drying, 65.63 g of intermediate was obtained, with a yield of 91.1%.

[0057] (II) Preparation of Mal-PEG2-CH2COOH by cyclization reaction Add 200 mL of toluene to a 500 mL three-necked flask, then add 40 g of intermediate and 0.75 g of concentrated sulfuric acid in sequence. Heat to 105-110 °C and reflux for 8 h while separating water.

[0058] Post-processing: The reaction solution was concentrated, and the crude product was purified by column chromatography using a dichloromethane / methanol mixed solvent to obtain 31.06 g Mal-PEG2-CH2COOH, with a yield of 83.4%.

[0059] The NMR results of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.27 (s, 1H), 6.71 (s, 2H), 4.13 (s, 2H), 3.76 – 3.62 (m, 8H). The results showed that its structure matched that of the target product Mal-PEG2-CH2COOH.

[0060] Example 4

[0061] (a) Preparation of intermediates by ring-opening addition reaction Add 250 mL of DMF to a 500 mL three-necked flask, then add 45 g of AEEA. Cool the reaction system to 0-5 °C, add 28.4 g of maleic anhydride in portions, and then heat to 30-35 °C for 5 h.

[0062] Post-processing: The reaction solution was concentrated, and then 250 mL of ice water was added to the residue. After stirring for a while to induce crystallization, the mixture was filtered. The filter cake was washed with a small amount of ice water and then slurried with 300 mL of ethyl acetate / n-heptane (1:5) mixed solvent. After drying, 62.61 g of intermediate was obtained, with a yield of 86.9%.

[0063] (II) Preparation of Mal-PEG2-CH2COOH by cyclization reaction Add 200 mL of toluene to a 500 mL three-necked flask, then add 40 g of intermediate and 1.32 g of p-toluenesulfonic acid in sequence. Heat to 115-120 °C and reflux for 8 h while separating water.

[0064] Post-processing: The reaction solution was concentrated, and the crude product was purified by column chromatography using a dichloromethane / methanol mixed solvent to obtain 32.70 g Mal-PEG2-CH2COOH, with a yield of 87.8%.

[0065] The NMR results of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.27 (s, 1H), 6.71 (s, 2H), 4.13 (s, 2H), 3.76 – 3.62 (m, 8H). The results showed that its structure matched that of the target product Mal-PEG2-CH2COOH.

[0066] In summary, the method for preparing a Mal-PEG2-CH2COOH according to the present invention has the advantages of simple operation, high safety, and green environmental protection.

[0067] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing Mal-PEG2-CH2COOH, characterized in that, include: Step S1 involves reacting AEEA with maleic anhydride to generate an intermediate, which is (Z)-2-(2-(N-hydroxyethyl)hydroxyethyl)carboxymethyl)maleic acid monoamide. Step S2 involves causing the intermediate to undergo a cyclization reaction to generate Mal-PEG2-CH2COOH.

2. The production method according to claim 1, characterized by, In step S1, the reaction is carried out in a first solvent, wherein the first solvent is selected from any one or more of dichloromethane, acetonitrile, acetone, and DMF.

3. The preparation method according to claim 2, characterized in that, The molar ratio of AEEA to maleic anhydride is 1:(1.0~1.5).

4. The preparation method according to claim 2, characterized in that, In step S1, the reaction temperature is 0~40℃ and the reaction time is 2~8 h.

5. The preparation method according to claim 2, characterized in that, In step S1, after the reaction is complete, the reaction solution is concentrated, water is added to precipitate crystals, filtered, slurried with ethyl acetate / n-heptane, and dried to obtain the intermediate.

6. The preparation method according to claim 1, characterized in that, In step S2, the cyclization reaction is carried out in a second solvent under the action of a catalyst, wherein the second solvent is selected from any one or more of toluene, xylene, and n-heptane.

7. The preparation method according to claim 6, characterized in that, In step S2, the catalyst is selected from any one or more of p-toluenesulfonic acid, concentrated sulfuric acid, and phosphoric acid.

8. The preparation method according to claim 6, characterized in that, In step S2, the molar ratio of the intermediate to the catalyst is 1:(0.01~0.4).

9. The preparation method according to claim 6, characterized in that, In step S2, the reaction temperature is 80~140℃ and the reaction time is 5~12 h.

10. The preparation method according to claim 6, characterized in that, In step S2, after the reaction is complete, the mixture is concentrated under reduced pressure and purified by column chromatography to obtain the Mal-PEG2-CH2COOH.