Method for synthesizing Fmoc-Ala-Ala-OH

Abstract

The invention discloses a method for synthesizing Fmoc-Ala-Ala-OH, and belongs to the technical field of chemical synthesis, and the method comprises the following steps: adding a solvent I into Fmoc-Ala-OH, dropwise adding oxalyl chloride at-30 DEG C to-20 DEG C, carrying out heat preservation until the reaction is completed, and carrying out vacuum decompression concentration to remove the solvent I, so as to obtain Fmoc-propylamine acyl chloride; adding a solvent II into the Fmoc-propylamine acyl chloride system, adding L-alanine while stirring, dropwise adding organic alkali, and concentrating under reduced pressure to obtain Fmoc-Ala-Ala-OH oily matter; and adding a solvent III, dropwise adding an acidifying reagent until the pH value is equal to 3.0, removing a water layer, washing an organic layer with saline water until the pH value is equal to 5, adding a solvent IV, precipitating a solid, and drying to obtain a finished product Fmoc-Ala-Ala-OH. According to the method, a low-temperature acylating chlorination process is utilized, Fmoc-Ala-OH is subjected to a low-temperature acylating chlorination reaction, generation of isomers is effectively avoided while Fmoc-propylamine acyl chloride is generated, organic alkali is adopted subsequently to participate in the reaction, Fmoc-propylamine acyl chloride and alanine are rapidly combined, and Fmoc-Ala-Ala-OH is obtained. And few byproducts are generated.

Description

Technical Field

[0001] The present invention relates to the field of chemical synthesis, and in particular to a method for synthesizing Fmoc-Ala-Ala-OH. Background Art

[0002] N-Fmoc-L-alanyl-L-alanine (Fmoc-Ala-Ala-OH) is a dipeptide widely used in the synthesis of peptides. At present, the synthesis and application of Fmoc-Ala-Ala-OH belong to an emerging field. The commonly used synthesis method is to first synthesize N-Fmoc-L-alanine succinimidyl ester (Fmoc-Ala-OSU), and then condense it with L-alanine (L-Ala-OH) to form an amide bond.

[0003] For example, Chinese patent publication number CN116789731A discloses a method for preparing a short peptide Fmoc-L-Ala-L-Ala-OH, and its synthesis steps are: first, Fmoc-L-Ala-OH is reacted with an activator HOR to prepare an active ester Fmoc-L-Ala-OR, and then Fmoc-L-Ala-OR is coupled with L-Ala-OH to prepare Fmoc-L-Ala-L-Ala-OH.

[0004] The technical route used in the prior art for synthesizing Fmoc-Ala-Ala-OH will produce more isomers, form more by-products, and also have the problem of using more raw materials. Summary of the invention

[0005] The invention aims to overcome the defect of many synthetic by-products in the prior art and provides a method for synthesizing Fmoc-Ala-Ala-OH.

[0006] To achieve the above object, the technical solution of the present invention comprises the steps of:

[0007] S1, add solvent I to Fmoc-Ala-OH, add oxalyl chloride dropwise at -30°C to -20°C, keep warm until the reaction is complete, and remove solvent I by vacuum concentration to prepare Fmoc-alanine chloride. The reaction is shown in Formula I:

[0008]

[0009] S2, adding solvent II to the Fmoc-alanine chloride system prepared in step S1, adding L-alanine under stirring, dropping an organic base, and concentrating under reduced pressure to obtain Fmoc-Ala-Ala-OH oily substance, the reaction is shown in formula II:

[0010]

[0011] S3, add solvent III to the Fmoc-Ala-Ala-OH oil, add an acidifying agent dropwise to pH = 3.0, remove the water layer, wash the organic layer with brine to pH = 5, add solvent IV, precipitate the solid and dry it to obtain the Fmoc-Ala-Ala-OH finished product.

[0012] In a preferred embodiment of the present invention, the solvent I is a halogenated hydrocarbon solvent such as dichloromethane, dichloroethane, etc., preferably dichloromethane.

[0013] In a preferred embodiment of the present invention, the solvent II is one of highly polar solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether or dichloromethane, preferably tetrahydrofuran.

[0014] In a preferred embodiment of the present invention, the solvent III is one of ethyl acetate, isopropyl acetate or n-butyl acetate, preferably ethyl acetate.

[0015] In a preferred embodiment of the present invention, the solvent IV is one of low polarity solvents such as n-heptane, n-hexane, petroleum ether, etc., preferably n-heptane.

[0016] In a preferred embodiment of the present invention, the organic base is one of pyridine, N,N'-diisopropylethylamine or triethylamine, preferably triethylamine.

[0017] In a preferred embodiment of the present invention, the acidifying agent is an aqueous inorganic acid solution such as hydrochloric acid, an aqueous sulfuric acid solution, an aqueous phosphoric acid solution, etc., preferably hydrochloric acid.

[0018] Beneficial effect: the present invention utilizes a low-temperature chlorination process to perform a low-temperature chlorination reaction on Fmoc-Ala-OH, and effectively avoids the generation of isomers while generating Fmoc-alanine chloride; an organic base is subsequently used to participate in the reaction, so that Fmoc-alanine chloride and alanine are quickly combined to obtain Fmoc-Ala-Ala-OH; the technical route provided by the present invention has fast and efficient reaction, less three wastes, and low cost.

[0019] In order to make the above features and advantages of the invention more obvious and easy to understand, embodiments are given below for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a characterization diagram of the product in Example 1 of the present invention.

[0021] Figure 2 This is a characterization diagram of the product in Example 2 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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.

[0023] Example 1

[0024] Add 31.1g Fmoc-Ala-OH and 500g dichloromethane to a 1000ml four-necked bottle, cool to -30°C, and then drop 26.0g oxalyl chloride into the system. After the dropwise addition is complete, control the temperature to -30°C and keep warm for 24 hours. After the reaction is completed, concentrate under reduced pressure to obtain Fmoc-alanine chloride.

[0025] 500 g of tetrahydrofuran and 9.0 g of alanine were added to Fmoc-alanine, and 16 g of triethylamine was added dropwise while stirring. The reaction system was stirred until it became clear and then concentrated to obtain Fmoc-Ala-Ala-OH oily substance.

[0026] 500 g of ethyl acetate was added to the Fmoc-Ala-Ala-OH oil, and hydrochloric acid was added dropwise until the system pH = 3. The aqueous layer was separated, and the organic layer was washed twice with 100 g of 15% brine, and then 400 g of n-heptane was added. The mixture was stirred until a large amount of solid precipitated, and then filtered. The filter cake was rinsed with 100 g of n-heptane and dried at 50° C. to obtain 19.1 g of Fmoc-Ala-Ala-OH product. The product was characterized as follows: Figure 1 shown.

[0027] Example 2

[0028] Add 31.1g Fmoc-Ala-OH and 500g dichloroethane to a 1000ml four-necked bottle, cool to -20°C, and then drop 23g oxalyl chloride into the system. After the dropwise addition is complete, control the temperature to -20°C and keep warm for 18 hours. After the reaction is completed, concentrate under reduced pressure to obtain Fmoc-alanine chloride.

[0029] 500 g of ethylene glycol dimethyl ether and 9.5 g of alanine were added to Fmoc-alanine, and 12.3 g of pyridine was added dropwise while stirring. The reaction system was stirred until it became clear and then concentrated to obtain Fmoc-Ala-Ala-OH oily substance.

[0030] 600 g of isopropyl acetate was added to the Fmoc-Ala-Ala-OH oil, and hydrochloric acid was added dropwise until the system pH = 3, the aqueous layer was separated, and the organic layer was washed twice with 150 g of 15% brine, and then 500 g of petroleum ether was added, and stirred until a large amount of solid precipitated, and then filtered, and the filter cake was rinsed with 100 g of petroleum ether and dried at 50° C. to obtain 18.2 g of Fmoc-Ala-Ala-OH product. The product characteristics are as follows: Figure 2 shown.

[0031] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims

1. A method for synthesizing Fmoc-Ala-Ala-OH, characterized in that: Includes steps: S1, add solvent I to Fmoc-Ala-OH, add oxalyl chloride dropwise at -30°C to -20°C, keep warm until the reaction is complete, and remove solvent I by vacuum concentration to prepare Fmoc-alanine chloride. The reaction is shown in Formula I: S2, adding solvent II to the Fmoc-alanine chloride system prepared in step S1, adding L-alanine under stirring, dropping an organic base, and concentrating under reduced pressure to obtain Fmoc-Ala-Ala-OH oily substance, the reaction is shown in formula II: S3, add solvent III to the Fmoc-Ala-Ala-OH oil, add an acidifying agent dropwise to pH = 3.0, remove the water layer, wash the organic layer with brine to pH = 5, add solvent IV, precipitate the solid and dry it to obtain the Fmoc-Ala-Ala-OH finished product.

2. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 1, characterized in that: The solvent I is a halogenated hydrocarbon solvent.

3. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 2, characterized in that: The solvent I is dichloromethane or dichloroethane.

4. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 3, characterized in that: The solvent II is one of tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether or dichloromethane.

5. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 4, characterized in that: The solvent III is one of ethyl acetate, isopropyl acetate or n-butyl acetate.

6. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 5, characterized in that: The solvent IV is one of n-heptane, n-hexane or petroleum ether.

7. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 6, characterized in that: The organic base is one of pyridine, N,N'-diisopropylethylamine or triethylamine.

8. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 7, characterized in that: The acidifying agent is an aqueous solution of an inorganic acid.

9. A method for synthesizing Fmoc-Ala-Ala-OH according to claim 8, characterized in that: The acidifying agent is one of hydrochloric acid, sulfuric acid or phosphoric acid.

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