Sieber resin as well as preparation method and application thereof

Abstract

The invention relates to the technical field of synthesis, in particular to Sieber resin and a preparation method and application thereof. The preparation method comprises the following steps: under the catalysis of a first catalyst, (9H-xanth-9-one-3-oxymethyl) resin and fluorenylmethoxycarbonyl amide are subjected to a first reaction in a first solvent, and Sieber resin is prepared; wherein the first catalyst comprises triacetoxyborohydride alkali metal salt and acetic acid, the general formula of the triacetoxyborohydride salt is M [BH (OAc) 3], and M is selected from Li, Na, K, Rb and Cs. According to the preparation method of the Sieber resin provided by the embodiment of the invention, the reaction steps are simplified, the synthesis efficiency is improved, the reaction conditions are mild and controllable, and the prepared Sieber resin is good in swelling property, stable in product performance and suitable for large-scale industrial production.

Description

Technical Field

[0001] This application relates to the field of peptide solid-phase synthesis technology, and in particular to Sieber resin, its preparation method, and its application. Background Technology

[0002] Solid-phase peptide synthesis (SPPS) is a highly efficient peptide synthesis technique that sequentially links amino acids to a solid support, gradually constructing the target peptide chain through repeated deprotection and coupling reactions. SPPS simplifies the cumbersome purification steps of traditional liquid-phase synthesis, significantly improving synthesis efficiency and product purity, and has become a key method in peptide research and drug development.

[0003] In SPPS, the choice of resin solid support directly affects synthesis efficiency, product purity, and yield. While commonly used Rink amide resins are widely used in the synthesis of peptide amides, steric hindrance can easily lead to decreased reaction efficiency in high-loading synthesis and other conditions.

[0004] Sieber resins, due to their low steric hindrance of side-chain functional groups, help reduce racemization side reactions during synthesis and can be cleaved under mild acidic conditions without affecting peptide activity, exhibiting high reaction efficiency and product purity, thus demonstrating significant advantages in peptide drug production.

[0005] However, traditional methods for synthesizing Sieber resins are typically cumbersome, inefficient, and require reduction with lithium borohydride or sodium borohydride. These materials are prone to violent reactions in humid air, releasing hydrogen gas and posing risks of combustion and explosion, increasing safety risks and management costs. Summary of the Invention

[0006] Therefore, the main objective of this application is to provide a method for preparing Sieber resin that simplifies reaction steps, improves synthesis efficiency, and enhances process safety.

[0007] A first aspect of this application provides a method for preparing Sieber resin, the method comprising the following steps: reacting (9H-mont-9-one-3-oxymethyl) resin and fluorenemethoxycarbonylamide in a first solvent under the catalysis of a first catalyst to prepare Sieber resin; wherein the structural formula of (9H-mont-9-one-3-oxymethyl) resin is as follows: P is a polymer resin; the first catalyst comprises a triacetoxyborohydride alkali metal salt and acetic acid, wherein the general formula of the triacetoxyborohydride salt is M[BH(OAc)3], and M is selected from Li, Na, K, Rb, and Cs.

[0008] In some embodiments, the (9H-zanton-9-one-3-oxomethyl) resin is prepared by the following steps: a chloromethyl resin and 3-hydroxy-9H-zanton-9-one are reacted in a second solvent under the catalysis of a second catalyst to prepare the (9H-zanton-9-one-3-oxomethyl) resin; wherein the structural formula of the chloromethyl resin is shown below: .

[0009] In some embodiments, the preparation method satisfies at least one of the following conditions: (1) the second catalyst is selected from at least one of sodium tert-butyloxide, sodium methoxide and sodium ethoxide; (2) the second solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran and 1,4-dioxane; (3) the particle size of the chloromethyl resin is 100 mesh to 200 mesh; (4) the temperature of the second reaction is 60°C to 100°C; (5) the time of the second reaction is 12h to 24h.

[0010] In some embodiments, P is selected from one of polystyrene-divinylbenzene copolymer resin, polyethylene-ethylene glycol-grafted polystyrene resin, and diethylene glycol dimethacrylate crosslinked polystyrene resin.

[0011] In some embodiments, the preparation method satisfies at least one of the following conditions: (1) the mass ratio of sodium triacetoxyborohydride to acetic acid is (5~15):1; (2) the mass of the first catalyst is 0.2~2 times that of the (9H-mont-9-one-3-oxymethyl) resin; (3) the mass of fluorene methoxycarbonylamide is 0.5~1.5 times that of the (9H-mont-9-one-3-oxymethyl) resin; (4) the first solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran and 1,4-dioxane; (5) the temperature of the first reaction is 30℃~45℃; (6) the time of the first reaction is 16h~24h.

[0012] In some embodiments, prior to the first reaction, the process further includes swelling the (9H-mont-9-one-3-oxymethyl) resin with a first solvent.

[0013] In some implementations, the first swelling treatment takes 15 to 30 minutes.

[0014] A second aspect of this application provides a Sieber resin prepared using the preparation method provided in the first aspect above.

[0015] In some embodiments, the Sieber resin satisfies at least one of the following conditions: (1) the swelling degree of the Sieber resin in N,N-dimethylformamide is 4.0 mL / g to 7.0 mL / g; (2) the sufficient swelling time of the Sieber resin in N,N-dimethylformamide is 2h to 6h; (3) the swelling degree of the Sieber resin in dichloromethane is 4.5 mL / g to 8.0 mL / g; (4) the sufficient swelling time of the Sieber resin in dichloromethane is 2h to 6h; (5) the degree of substitution of the Sieber resin is 0.2 mmol / g to 1 mmol / g.

[0016] A third aspect of this application provides the use of the Sieber resin provided in the second aspect above as a carrier in the solid-phase synthesis of peptides.

[0017] The method for preparing Sieber resin provided in this application uses (9H-monoton-9-one-3-oxymethyl) resin and fluorenemethyloxycarbonylamide as raw materials. Under the action of triacetoxyborohydride alkali metal salts (such as sodium triacetoxyborohydride) and acetic acid, a one-step reductive amination reaction is achieved, simultaneously realizing the two-step transformation of reduction and amidation reactions required in traditional synthesis processes. This significantly simplifies the reaction steps and improves synthesis efficiency. Furthermore, replacing the traditional lithium borohydride or sodium borohydride reducing agents with the more stable and milder triacetoxyborohydride alkali metal salt not only reduces the risk of combustion and explosion caused by violent reactions with water, greatly improving process safety, but also makes the reaction conditions milder and more controllable. The resulting Sieber resin exhibits good swelling properties and stable product performance, making it more suitable for large-scale industrial production. Attached Figure Description

[0018] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0019] Figure 1 This is a schematic diagram of the reaction route of Sieber resin in one embodiment of this application. Detailed Implementation

[0020] Reference will now be made to detailed embodiments of this application, one or more of which are described below. Each example is provided for explanation and not for limitation of this application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0021] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0022] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0023] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0024] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0025] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0026] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0027] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0028] Solid-phase peptide synthesis (SPPS) is a highly efficient peptide synthesis technique that sequentially links amino acids to a solid support, gradually constructing the target peptide chain through repeated deprotection and coupling reactions. SPPS simplifies the cumbersome purification steps of traditional liquid-phase synthesis, significantly improving synthesis efficiency and product purity, and has become a key method in peptide research and drug development.

[0029] In SPPS, the choice of resin solid support directly affects synthesis efficiency, product purity, and yield. While commonly used Rink amide resins are widely used in the synthesis of peptide amides, steric hindrance can easily lead to decreased reaction efficiency in high-loading synthesis and other conditions.

[0030] Sieber resins, due to their low steric hindrance of side-chain functional groups, help reduce racemization side reactions during synthesis and can be cleaved under mild acidic conditions without affecting peptide activity, exhibiting high reaction efficiency and product purity, thus demonstrating significant advantages in peptide drug production.

[0031] However, traditional methods for synthesizing Sieber resins are typically cumbersome, inefficient, and require reduction with lithium borohydride or sodium borohydride. These materials are prone to violent reactions in humid air, releasing hydrogen gas and posing risks of combustion and explosion, increasing safety risks and management costs.

[0032] The applicant's research found that sodium borohydride or lithium borohydride have excessively strong reducing properties, easily generating byproducts. Furthermore, as non-selective reducing agents, sodium borohydride or lithium borohydride is difficult to achieve reductive amination in systems containing both ketone carbonyl and amide groups, making it impossible to combine the reduction and amination reactions. The specific synthetic route involves first reducing the ketone structure to a ethanol intermediate using sodium borohydride or lithium borohydride, followed by the subsequent amination reaction. This step-by-step synthetic route is not only cumbersome and inefficient but also affects the overall yield. In addition, the poor stability of the ethanol intermediate further limits reaction efficiency and product purity.

[0033] Therefore, in a first aspect, this application provides a method for preparing Sieber resin, the method comprising the following steps: (9H-mont-9-one-3-oxymethyl) resin and fluorene methoxycarbonylamide undergo a first reaction in a first solvent under the catalysis of a first catalyst to prepare Sieber resin.

[0034] The structural formula of (9H-zanton-9-one-3-oxomethyl) resin is shown below:

[0035] ;

[0036] P represents a polymer resin;

[0037] The first catalyst comprises an alkali metal salt of triacetoxyborohydride and acetic acid. The general formula of the triacetoxyborohydride is M[BH(OAc)3], where M is selected from Li, Na, K, Rb, and Cs.

[0038] The method for preparing Sieber resin provided in this application uses (9H-monoton-9-one-3-oxymethyl) resin and fluorenemethyloxycarbonylamide as raw materials. Under the action of triacetoxyborohydride alkali metal salts (such as sodium triacetoxyborohydride) and acetic acid, a one-step reductive amination reaction is achieved, simultaneously realizing the two-step transformation of reduction and amidation reactions required in traditional synthesis processes. This significantly simplifies the reaction steps and improves synthesis efficiency. Furthermore, replacing the traditional lithium borohydride or sodium borohydride reducing agents with the more stable and milder triacetoxyborohydride alkali metal salt not only reduces the risk of combustion and explosion caused by violent reactions with water, greatly improving process safety, but also makes the reaction conditions milder and more controllable. The resulting Sieber resin exhibits good swelling properties and stable product performance, making it more suitable for large-scale industrial production.

[0039] In some embodiments, P is selected from one of polystyrene-divinylbenzene copolymer resin, polyethylene-ethylene glycol-grafted polystyrene resin, and diethylene glycol dimethacrylate crosslinked polystyrene resin.

[0040] In some embodiments, the mass ratio of sodium triacetoxyborohydride to acetic acid is (5~15):1. Exemplarily, the mass ratio of sodium triacetoxyborohydride to acetic acid can be, but is not limited to, 5:1, 8:1, 10:1, 12:1, or 15:1.

[0041] In some embodiments, the equivalent of the first catalyst is 5 to 10 times that of the (9H-mont-9-one-3-oxymethyl) resin. Exemplarily, the equivalent of the first catalyst can be, but is not limited to, 5, 6, 7, 8, 9, or 10 times that of the (9H-mont-9-one-3-oxymethyl) resin.

[0042] In some embodiments, the mass of fluorenemethoxycarbonylamide is 0.5 to 1.5 times that of (9H-mont-9-one-3-oxymethyl) resin. Exemplarily, the mass of fluorenemethoxycarbonylamide can be, but is not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, or 1.5 times that of (9H-mont-9-one-3-oxymethyl) resin.

[0043] In some embodiments, the temperature of the first reaction is 30°C to 45°C. Exemplarily, the temperature of the first reaction can be, but is not limited to, 30°C, 33°C, 36°C, 39°C, 42°C, or 45°C.

[0044] In some embodiments, the first solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone, tetrahydrofuran, and 1,4-dioxane.

[0045] In some implementations, the first reaction time is 16h to 24h. Exemplarily, the first reaction time can be, but is not limited to, 16h, 18h, 20h, 22h, or 24h.

[0046] In some embodiments, prior to the first reaction, the process further includes: subjecting the (9H-mont-9-one-3-oxymethyl) resin to a first swelling treatment using a first solvent.

[0047] In some embodiments, the first swelling treatment time is 15 min to 30 min. For example, the first swelling treatment time can be, but is not limited to, 15 min, 18 min, 21 min, 24 min, 27 min, or 30 min.

[0048] In some embodiments, (9H-zanton-9-one-3-oxomethyl) resin is prepared by the following steps: under the catalysis of a second catalyst, chloromethyl resin and 3-hydroxy-9H-zanton-9-one undergo a second reaction in a second solvent to prepare (9H-zanton-9-one-3-oxomethyl) resin.

[0049] The structural formula of the chloromethyl resin is shown below: .

[0050] In some embodiments, the second catalyst is selected from at least one of sodium tert-butyloxide, sodium methoxide, and sodium ethoxide.

[0051] When P is polystyrene-divinylbenzene copolymer resin, chloromethyl resin is chloromethyl polystyrene-divinylbenzene copolymer resin.

[0052] In some embodiments, the degree of substitution of the chloromethyl resin is 0.4 mmol / g to 3.0 mmol / g. Exemplarily, the degree of substitution of the chloromethyl resin can be, but is not limited to, 0.4 mmol / g, 0.8 mmol / g, 1.2 mmol / g, 1.6 mmol / g, 2.0 mmol / g, 2.4 mmol / g, 2.8 mmol / g, and 3.0 mmol / g.

[0053] In some embodiments, the particle size of the chloromethyl resin is 100 to 200 mesh. Exemplarily, the particle size of the chloromethyl resin can be, but is not limited to, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, and 200 mesh.

[0054] In some embodiments, the second solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone, tetrahydrofuran, and 1,4-dioxane.

[0055] In some embodiments, the temperature of the second reaction is 60°C to 100°C. Exemplarily, the temperature of the second reaction can be, but is not limited to, 60°C, 70°C, 80°C, 90°C, or 100°C.

[0056] In some embodiments, the second reaction time is 12h to 24h. Exemplarily, the second reaction time can be, but is not limited to, 12h, 14h, 16h, 18h, 20h, 22h, or 24h.

[0057] In some embodiments, under the catalysis of a second catalyst, chloromethyl resin and 3-hydroxy-9H-zanton-9-one undergo a second reaction in a second solvent. Before preparing (9H-zanton-9-one-3-oxymethyl) resin, the method further includes the following step: subjecting the chloromethyl resin to a second swelling treatment using a second solvent.

[0058] In some embodiments, the second swelling treatment takes 20 to 40 minutes. For example, the second swelling treatment may take, but is not limited to, 20 minutes, 25 minutes, 30 minutes, 35 minutes, or 40 minutes.

[0059] like Figure 1As shown, this application prepares (9H-junto-9-one-3-oxomethyl) resin by reacting chloromethyl resin and 3-hydroxy-9H-junto-9-one under specific solvent, specific catalyst and specific process conditions. Then, under the action of sodium triacetoxyborohydride and acetic acid, the (9H-junto-9-one-3-oxomethyl) resin is subjected to a reductive amination reaction with fluorenemethyloxycarbonylamide under specific process conditions to prepare Sieber resin. Sieber resin with significantly improved performance can be prepared, and the preparation process is simple and has high process safety.

[0060] Specifically, the Sieber resin prepared in this application has excellent swelling properties, strong chemical stability, high functional group density, and good long-term stability. As a carrier, it is beneficial to improve the efficiency and quality of peptide solid-phase synthesis.

[0061] A second aspect of this application provides a Sieber resin prepared using the preparation method provided in the first aspect above.

[0062] In some embodiments, the swelling degree of Sieber resin in N,N-dimethylformamide is 4.0 mL / g to 7.0 mL / g. Exemplarily, the swelling degree of Sieber resin in N,N-dimethylformamide can be, but is not limited to, 4.0 mL / g, 4.5 mL / g, 5.0 mL / g, 5.5 mL / g, 6.0 mL / g, 6.5 mL / g, and 7.0 mL / g.

[0063] In some embodiments, the sufficient swelling time of Sieber resin in N,N-dimethylformamide is 2 h to 6 h. Exemplarily, the sufficient swelling time of Sieber resin in N,N-dimethylformamide can be, but is not limited to, 2 h, 3 h, 4 h, 5 h, or 6 h.

[0064] In some embodiments, the swelling degree of Sieber resin in dichloromethane is 4.5 mL / g to 8.0 mL / g. Exemplarily, the swelling degree of Sieber resin in dichloromethane can be, but is not limited to, 4.5 mL / g, 5.0 mL / g, 5.5 mL / g, 6.0 mL / g, 6.5 mL / g, 7.0 mL / g, 7.5 mL / g, and 8.0 mL / g.

[0065] In some embodiments, the sufficient swelling time of Sieber resin in dichloromethane is 2h to 6h. Exemplarily, the sufficient swelling time of Sieber resin in dichloromethane can be, but is not limited to, 2h, 3h, 4h, 5h, or 6h.

[0066] In some embodiments, the degree of substitution of the Sieber resin is 0.2 mmol / g to 1 mmol / g. Exemplarily, the degree of substitution of the Sieber resin can be, but is not limited to, 0.2 mmol / g, 0.3 mmol / g, 0.4 mmol / g, 0.5 mmol / g, 0.6 mmol / g, 0.7 mmol / g, 0.8 mmol / g, and 1 mmol / g.

[0067] A third aspect of this application provides the use of the Sieber resin provided in the second aspect above as a carrier in the solid-phase synthesis of peptides.

[0068] The present application will be further described below with reference to specific embodiments and comparative examples.

[0069] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0070] Example 1

[0071] This embodiment provides a method for preparing Sieber resin.

[0072] (1) 100g of chloromethyl polystyrene-divinylbenzene copolymer resin with a particle size range of 100~200 mesh and a degree of substitution of 0.50mmol / g and 1000mL of DMAc were added to a 2000mL three-necked flask and stirred and swollen at 20℃ for 30min. Then 4.0g of sodium tert-butoxide was added as a catalyst and 15.9g of 3-hydroxy-9H-junton-9-one was added. The reaction was carried out at 80℃ for 24h. After the reaction was completed, the solid product was separated by vacuum filtration using a Buchner funnel. The solid product was washed twice with 500mL of DMF and twice with 500mL of dichloromethane. It was then placed in a vacuum oven and dried at 60℃ to constant weight to obtain (9H-junton-9-one-3-oxymethyl) resin.

[0073] (2) 100g of 9H-zanton-9-one-3-oxomethyl) resin with a particle size of 100-200 mesh and 1000 mL of DMF were added to a 2000 mL three-necked flask and stirred and swollen at 20 °C for 30 min. Then, 33.0g of fluorene methoxycarbonylamide, 3g of glacial acetic acid and 30g of sodium triacetoxyborohydride were added and stirred at 30 °C for 24 h. After the reaction was completed, the solid product was separated by vacuum filtration using a sintered glass funnel to obtain moist Sieber resin. After washing twice with 500 mL of DMF, twice with 500 mL of dichloromethane, twice with 500 mL of tetrahydrofuran / water (1:1, v / v) and twice with 500 mL of methanol, the resin was placed in a vacuum oven and dried at 60 °C to constant weight to obtain Sieber resin with a degree of substitution of 0.30 mmol / g.

[0074] Example 2

[0075] This embodiment provides a method for preparing Sieber resin.

[0076] (1) 100 g of chloromethyl polystyrene-divinylbenzene copolymer resin with a particle size range of 100~200 mesh and a degree of substitution of 1.0 mmol / g and 1000 mL of DMAc were added to a 2000 mL three-necked flask and stirred and swollen at 20 °C for 30 min. Then 8.0 g of sodium tert-butoxide was added as a catalyst and 31.5 g of 3-hydroxy-9H-junton-9-one was added. The reaction was carried out at 80 °C for 24 h. After the reaction was completed, the solid product was separated by vacuum filtration using a Buchner funnel. The solid product was washed twice with 500 mL of DMF and twice with 500 mL of dichloromethane. It was then placed in a vacuum oven and dried at 60 °C to constant weight to obtain (9H-junton-9-one-3-oxymethyl) resin.

[0077] (2) 100 g of (9H-zanton-9-one-3-oxymethyl) resin with a particle size range of 100-200 mesh and 1000 mL of DMF were added to a 2000 mL three-necked flask and stirred and swollen at 20 °C for 30 min. Then, 60.3 g of fluorene methoxycarbonylamide, 7.3 g of glacial acetic acid and 36.5 g of sodium triacetoxyborohydride were added and stirred at 30 °C for 24 h. After the reaction was completed, the solid product was separated by vacuum filtration using a sintered funnel to obtain moist Sieber resin. After washing twice with 500 mL of DMF, twice with 500 mL of dichloromethane, twice with 500 mL of tetrahydrofuran / water (1:1, v / v) and twice with 500 mL of methanol, the resin was placed in a vacuum oven and dried at 60 °C to constant weight to obtain Sieber resin with a degree of substitution of 0.50 mmol / g.

[0078] Example 3

[0079] This embodiment provides a method for preparing Sieber resin.

[0080] (1) 100 g of chloromethyl polystyrene-divinylbenzene copolymer resin with a particle size range of 100~200 mesh and a degree of substitution of 1.84 mmol / g and 1000 mL of DMAc were added to a 2000 mL three-necked flask and stirred and swollen at 20 °C for 30 min. Then 14.9 g of sodium tert-butoxide was added as a catalyst and 58.5 g of 3-hydroxy-9H-junton-9-one was added. The reaction was carried out at 80 °C for 24 h. After the reaction was completed, the solid product was separated by vacuum filtration using a Buchner funnel. The solid product was washed twice with 500 mL of DMF and twice with 500 mL of dichloromethane. It was then placed in a vacuum oven and dried at 60 °C to constant weight to obtain (9H-junton-9-one-3-oxomethyl) resin.

[0081] (2) 100 g of 9H-zanton-9-one-3-oxomethyl) resin with a particle size range of 100-200 mesh and 1000 mL of N,N-dimethylformamide solvent were added to a 2000 mL three-necked flask and stirred and swollen at 20 °C for 30 min. Then, 99.8 g of fluorene methoxycarbonylamide, 12.1 g of glacial acetic acid and 181.5 g of sodium triacetoxyborohydride were added and stirred at 30 °C for 24 h. After the reaction was completed, the solid product was separated by vacuum filtration using a sintered glass funnel to obtain moist Sieber resin. The resin was washed twice with 500 mL of DMF, three times with 500 mL of dichloromethane, three times with 500 mL of tetrahydrofuran / water (1:1, v / v), and twice with 500 mL of methanol. The resin was then dried in a vacuum oven at 60 °C to constant weight to obtain Sieber resin with a degree of substitution of 0.70 mmol / g.

[0082] Example 4

[0083] The preparation method of Sieber resin in this embodiment is basically the same as that in Example 1, except that:

[0084] In step (2), the amount of glacial acetic acid used is 2.0g, and the amount of sodium triacetoxyborohydride used is 28g.

[0085] This yielded a Sieber resin with a degree of substitution of 0.27 mmol / g.

[0086] Example 5

[0087] The preparation method of Sieber resin in this embodiment is basically the same as that in Example 1, except that:

[0088] In step (2), the amount of glacial acetic acid used is 5.0g, and the amount of sodium triacetoxyborohydride used is 25g.

[0089] This yielded a Sieber resin with a degree of substitution of 0.31 mmol / g.

[0090] Example 6

[0091] The preparation method of Sieber resin in this embodiment is basically the same as that in Example 1, except that:

[0092] In step (2), the amount of glacial acetic acid used is 10g, and the amount of sodium triacetoxyborohydride used is 20g.

[0093] This yielded a Sieber resin with a degree of substitution of 0.41 mmol / g.

[0094] Comparative Example 1

[0095] This comparative example provides a method for preparing Sieber resin.

[0096] The preparation method of Sieber resin in this embodiment is basically the same as that in Example 1, except that:

[0097] In step (2), sodium triacetoxyborohydride is replaced with an equimolar amount of sodium borohydride (5.4 g).

[0098] When sodium borohydride was added, a large number of bubbles were observed to be generated in the system, accompanied by exothermic reactions; finally, a Sieber resin with a degree of substitution of 0.07 mmol / g was obtained.

[0099] Comparative Example 2

[0100] This comparative example provides a method for preparing Sieber resin.

[0101] The preparation method of Sieber resin in this embodiment is basically the same as that in Example 2, except that:

[0102] In step (2), sodium triacetoxyborohydride is replaced with an equimolar amount of sodium borohydride (6.5g).

[0103] When sodium borohydride was added, a large number of bubbles were observed to be generated in the system, accompanied by exothermic reaction; finally, a Sieber resin with a degree of substitution of 0.31 mmol / g was obtained.

[0104] Comparative Example 3

[0105] This comparative example provides a method for preparing Sieber resin.

[0106] The preparation method of Sieber resin in this embodiment is basically the same as that in Example 3, except that:

[0107] In step (2), sodium triacetoxyborohydride is replaced with an equimolar amount of sodium borohydride (32.4 g).

[0108] When sodium borohydride was added, a large number of bubbles were observed to be generated in the system, accompanied by exothermic reaction; finally, a Sieber resin with a degree of substitution of 0.1 mmol / g was obtained.

[0109] Comparative Example 4

[0110] The preparation method of Sieber resin in this comparative example is basically the same as that in Example 1, except that:

[0111] In step (2), glacial acetic acid is not added.

[0112] No target Sieber resin product was detected after the reaction system was stirred for the specified time.

[0113] Comparative Example 5

[0114] The preparation method of Sieber resin in this comparative example is basically the same as that in Example 2, except that:

[0115] In step (2), glacial acetic acid is not added.

[0116] No target Sieber resin product was detected after the reaction system was stirred for the specified time.

[0117] Comparative Example 6

[0118] The preparation method of Sieber resin in this comparative example is basically the same as that in Example 3, except that:

[0119] In step (2), glacial acetic acid is not added.

[0120] No target Sieber resin product was detected after the reaction system was stirred for the specified time.

[0121] Comparative Example 7

[0122] The preparation method of Sieber resin in this comparative example is basically the same as that in Example 1, except that:

[0123] In step (2), glacial acetic acid is replaced with an equimolar amount of phosphoric acid (4.9g).

[0124] No target Sieber resin product was detected after the reaction system was stirred for the specified time.

[0125] Comparative Example 8

[0126] The preparation method of Sieber resin in this comparative example is basically the same as that in Example 2, except that:

[0127] In step (2), glacial acetic acid is replaced with an equimolar amount of phosphoric acid (11.9g).

[0128] No target Sieber resin product was detected after the reaction system was stirred for the specified time.

[0129] Comparative Example 9

[0130] The preparation method of Sieber resin in this comparative example is basically the same as that in Example 3, except that:

[0131] In step (2), glacial acetic acid is replaced with an equimolar amount of phosphoric acid (19.7g).

[0132] No target Sieber resin product was detected after the reaction system was stirred for the specified time.

[0133] Performance testing

[0134] (1) Substitution test

[0135] Take 0.1 g of Sieber resin from Examples 1-6 and Comparative Examples 1-3 into a test tube, add 8 mL of N,N-dimethylformamide and 2 mL of piperidine solution, stir at room temperature for 30 min, filter and recover the filtrate, add acetonitrile, dilute to 100 mL in a volumetric flask, measure the absorbance with a UV-Vis spectrophotometer, and calculate the degree of substitution (mmol / g) from the standard curve fitted by the standard.

[0136] (2) Swelling performance test

[0137] 0.1g of Sieber resin from Examples 1-6 and Comparative Examples 1-3 were placed into 25 mL test tubes, and swollen in 15 mL of N,N-dimethylformamide and 15 mL of dichloromethane, respectively. The volume of resin in the test tubes was recorded, the degree of swelling of the resin in different solutions was calculated, and the time to complete swelling was recorded. The average value of three parallel experiments was taken.

[0138] Swelling degree: The ratio of resin volume (mL) to dry resin mass (g) after swelling equilibrium.

[0139] Complete swelling time: The time from the addition of solvent until the resin volume no longer increases.

[0140] The test results are shown in Table 1.

[0141] Table 1

[0142]

[0143] As shown in Table 1, comparing Examples 1-6 and Comparative Examples 1-3, it can be seen that the Sieber resin prepared by the preparation method provided in this application has a higher functional group density and better swelling performance, and a shorter swelling time.

[0144] Comparing Examples 1-3 and Comparative Examples 1-3, the only difference is the replacement of sodium triacetoxyborohydride with an equimolar amount of sodium borohydride. This results in the generation of numerous bubbles and exothermic reactions within the system. Furthermore, the Sieber resin prepared using sodium borohydride exhibits extremely low substitution and poor swelling properties. Possible reasons include: sodium borohydride has excessively strong reducing properties and lacks selectivity, preventing direct reductive amination in one-pot preparation and thus affecting the formation of Sieber resin; additionally, sodium borohydride decomposes violently under acidic conditions, releasing hydrogen gas, which is not only unsafe but may also damage the resin's skeletal structure, thereby affecting its swelling properties.

[0145] Comparing Examples 1-3 and Comparative Examples 4-6, the only difference is that acetic acid was not used for catalysis. As a result, no target product was detected in the reaction system, proving that acetic acid played an important catalytic role in the reaction system.

[0146] Comparing Examples 1-3 and Comparative Examples 7-9, it can be seen that the only difference is that acetic acid is replaced with an equimolar amount of phosphoric acid. As a result, no target product was detected in the reaction system. The possible reason is that sodium triacetoxyborohydride cannot exist stably in phosphoric acid and is prone to decomposition and failure, resulting in the loss of reducing power.

[0147] Comparing Examples 1-3 and Examples 4-6, it can be seen that when the mass ratio of sodium triacetoxyborohydride to acetic acid is controlled in the range of (5-15):1, the reaction can proceed efficiently, the obtained Sieber resin has a high degree of substitution, and exhibits excellent swelling properties in both DMF and dichloromethane.

[0148] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing Sieber resin, characterized in that, Includes the following steps: Sieber resin was prepared by reacting (9H-mont-9-one-3-oxymethyl) resin and fluorene methoxycarbonyl amide in a first solvent under the catalysis of a first catalyst. The structural formula of the (9H-zanton-9-one-3-oxomethyl) resin is shown below: ； P represents a polymer resin; The first catalyst comprises a triacetoxyborohydride alkali metal salt and acetic acid, wherein the general formula of the triacetoxyborohydride salt is M[BH(OAc)3], and M is selected from Li, Na, K, Rb, and Cs.

2. The preparation method according to claim 1, characterized in that, The (9H-9-one-3-oxymethyl) resin was prepared using the following steps: In the presence of a second catalyst, chloromethyl resin and 3-hydroxy-9H-zanton-9-one are subjected to a second reaction in a second solvent to prepare (9H-zanton-9-one-3-oxymethyl) resin. The structural formula of the chloromethyl resin is shown below: 。 3. The preparation method according to claim 2, characterized in that, At least one of the following conditions must be met: (1) The second catalyst is selected from at least one of sodium tert-butyloxide, sodium methoxide, and sodium ethoxide; (2) The second solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran and 1,4-dioxane; (3) The particle size of the chloromethyl resin is 100 mesh to 200 mesh; (4) The temperature of the second reaction is 60℃~100℃; (5) The second reaction takes 12h to 24h.

4. The preparation method according to any one of claims 1 to 3, characterized in that, P is selected from one of polystyrene-divinylbenzene copolymer resin, polyethylene-ethylene glycol-grafted polystyrene resin, and diethylene glycol dimethacrylate crosslinked polystyrene resin.

5. The preparation method according to any one of claims 1 to 3, characterized in that, At least one of the following conditions must be met: (1) The mass ratio of the sodium triacetoxyborohydride to the acetic acid is (5~15):1; (2) The mass of the first catalyst is 0.2 to 2 times that of the (9H-mont-9-one-3-oxymethyl) resin; (3) The mass of the fluorene methoxycarbonyl amide is 0.5 to 1.5 times that of the (9H-mont-9-one-3-oxymethyl) resin; (4) The first solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran and 1,4-dioxane; (5) The temperature of the first reaction is 30℃~45℃; (6) The reaction time of the first reaction is 16h~24h.

6. The preparation method according to any one of claims 1 to 3, characterized in that, Prior to the first reaction, the following is also included: The (9H-mont-9-one-3-oxymethyl) resin was subjected to a first swelling treatment using a first solvent.

7. The preparation method according to claim 6, characterized in that, The first swelling treatment time is 15 min to 30 min.

8. A Sieber resin, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 7.

9. The Sieber resin as described in claim 8, characterized in that, At least one of the following conditions must be met: (1) The swelling degree of the Sieber resin in N,N-dimethylformamide is 4.0 mL / g to 7.0 mL / g; (2) The full swelling time of the Sieber resin in N,N-dimethylformamide is 2h~6h; (3) The swelling degree of the Sieber resin in dichloromethane is 4.5 mL / g to 8.0 mL / g; (4) The full swelling time of the Sieber resin in dichloromethane is 2h~6h; (5) The degree of substitution of the Sieber resin is 0.2 mmol / g to 1 mmol / g.

10. The use of the Sieber resin as a carrier in solid-phase polypeptide synthesis as described in claim 8 or 9.

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