KR101148262B1 - The process for the simultaneous protection and activation of amino acids - Google Patents

Abstract

PURPOSE: A method for preparing amino acid derivatives in which amine group and carboxyl group are protected is provided to enhance carboxyl group reactivity. CONSTITUTION: An amine group of general formula I is protected with trifluoroacetyl groups. A method for preparing amino acid derivatives in which carboxyl groups are protected in a hydroxy imidester form comprises: a step of reacting N-hydroxy succinimide of chemical formula III with trifluoroacetic acid(CF_3COOH) under the presence of trichloromethyl chloroformate of chemical formula II and triethyl amine; and a step of adding amino acid. The reaction is performed at 0~35°C.

Description

The process for the simultaneous protection and activation of amino acids}

 The present invention protects the amine functionality in the synthesis of key intermediates in the field of fine chemicals such as peptide synthesis and pharmaceuticals or pesticides, and increases the reactivity of the carboxyl group to play an important role in synthesizing more useful substances. The present invention relates to a novel production method for protecting an amine group by protecting the trifluoroacetyl group, and converting the carboxyl group into a state of increasing the reactivity of the hydroxy succinimide ester form, thereby protecting the amine group and increasing the reactivity. .

 In general, after protecting the amine of an amino acid with a protecting group in the production of peptide bonds, a key component of the protein, the carboxylic acid portion of the amino acid is known as N-trifluoroacetoxy succinimide (abbreviated as TFA-NHS). The carboxylic acid moiety is transformed into hydroxy succinimide ester form, which greatly increases the reactivity, which facilitates the reaction with another amino acid, thereby producing a desired peptide bond. The method was already described by Zonnal Obshchei Khimii 45 vol. 11, 2497, in 1975 by Ponomareva-Stepnaya, MA.

There are several known methods for protecting nitrogen in amino acids. First, acetyl groups are introduced. Shibagaki et al., Published in 1989, Bulletin of the Chemical Society of Japan, Vol. To introduce amine and acetic acid, the reaction was heated at 200 ° C. for 5 hours in the presence of Hydrous Zirconium (IV) oxide to complete the N-acetylation reaction. de Vries et al. reported that in the literature published in Tetrahedron Letters, vol. 41, page 2467, amines and CH ₃ CN were converted to platinum (II) to synthesize N-acetylamine derivatives. The reaction was carried out at 160 ° C. for 5 hours in the presence of a catalyst to obtain the target compound. Kulkarni et al., In the literature published in Green Chemistry Vol. 2, pp. 104, 2000, synthesized N-acetylamine derivatives by heating amine and acetic acid at 116 ℃ for 5 hours in the presence of a catalyst containing HY-Zeolite. Synthesized. Chen et al. Synthesized N-acetylamine derivatives in the literature published in Organic Letters, vol. 3, pp. 3729, 2001, heated amine and acetic acid at 50 ° C. for 3 hours in the presence of an acylation catalyst containing Vanadyl Triflate. The desired compound was synthesized. Kumar et al., 2002, published in the Journal of Molecular Catalysis A: Chemical, Vol. 181, pp. 207, amine and acetic acid were heated at 110-125 ° C for 2 hours in the presence of Lewis acid catalyst containing Yttria-Zirconia. Synthesized. Sreedha et al., In the 2003 Journal of Molecular Catalysis A: Chemical, Vol. 191, pp. 141, amine and acetic acid were heated at 116 ° C. for 2 hours in the presence of an activated carbon catalyst containing Iron (III) oxide. Was synthesized. In 2003, Ranu et al., Published in Green Chemistry Vol. 5, pp. 44, synthesized the desired compound by reacting amine and acetic anhydride at 80-85 ° C for 2 hours without using a solvent. On the other hand, since the conditions when the trifluoroacetyl group is removed instead of the acetyl group are relatively gentle compared to other protecting groups and are easily applicable to large scale planting, a preferred method of introducing trifluoroacetyl groups into amines of amino acids has long been proposed. Efforts have been made in many ways. In 1952, EJ Broune et al. Introduced trifluoroacetyl groups in amines using trifluoroacetic anhydride (CF ₃ CO-O-COCF ₃ ) in a paper published in the Journal of Chemical Socity 4014. Acetic anhydride has a low boiling point, high volatility, and high corrosiveness, making it a technology that can be handled only in a small laboratory system. In 1955, M. Calvin et al. Introduced trifluoroacetyl groups in amines using S-ethyl trifluorothioacetate in a paper published in Journal of American Chemical Socity Vol. 77, pp. 2779. Due to its strong smell, it did not lead to industrialization and eventually exceeded the technical level of the previous method. In 1960, HA Staab et al. Angew. Chem. In a paper published on page 72, 35, N- (trifluoroacetyl) imidazole was synthesized and reacted with amine to introduce trifluoroacetyl group into amine. However, N- (trifluoroacetyl) imidazole itself is sensitive to moisture, There was a limit to dealing. In the late 1970s, attempts were made to introduce trifluoroacetyl groups into amines using ethyl trifluoro-acetate.In 1979, TJ Curphey published a paper in Journal of Organic Chemistry, Vol. 44, page 2805. The study using ethyl trifluoroacetate seemed to be the mainstream when K. Prasad et al. Published a paper using ethyl trfluoroacetate on Tetrahedron Letters, vol. 36, 7357, and in 2000, M. Parashad et al. Published on Tetrahedron Letters, vol. 41, 9957. The method has the advantage of commercialization of ethyl trifluoroacetate, but the conditions for introducing trifluoroacetyl group into the amine are high, requiring high temperatures of more than 85 degrees Celsius or low yield, especially M. Parashad et al. This paper, published in Tetrahedron Letters, vol. 41, pp. 9957, uses 4-dimethylaminopyridine as a catalyst, but at 24 degrees C. The introduction of an acetyl group to the method ineffective trifluoromethyl provided that the reaction is complete be between adverse events. In addition, T. Kaumi et al. Used 2-[(trifluorofluoro) oxy] pyridine as a reagent for introducing trifluoroacetyl groups into amines, trifluoro triflate for TR Forbus, and trifluoroacetyl benzotrizole for AR Katritzky et al. Although they were used as acetyl group introduction reagents, these reagents were limited methods such as by-product generation and the use of non-commercialized reagents to directly introduce trifluoroacetyl groups into amines. Unlike these methods, the trifluoroacetyl group was activated in a slightly different direction from the study of introducing a trifluoroacetyl group into the amine using a reagent that has been somewhat more reactive by introducing a trifluoroacetyl group into the amine. In order to introduce trifluoroacetyl groups by directly reacting amines with trifluoroacetic acid instead of using an introduction reagent, research was actively conducted. In 2003, J. Salazar et al. Published in Journal of Fluorine Chemistry, vol. In this paper, trifluoroacetyl groups were introduced by reacting amines with trifluoroacetic acid by sculpting microwave special wavelengths.In more recently, in 2007, J. Charris et al. Published a paper in Journal of Fluorine Chemistry, Vol. 128, p. 566. Phosphorus pentoxide (P ₂ O ₅ ) and Hexamethyldisiloxane made by boiling 2 hours in benzene Tridyl acetyl group was introduced by directly reacting amine and trifluoroacetic acid using cid trimethylsilylester as a water-absorbing condensation reagent, but all of them used special equipment or the first step to make condensation reagent and using trifluoride Multi-step reactions, such as the second step of reacting roacetic acid and amines, had to be used and yields were not satisfactory. In the most recent 2009, Y. Kikugawa et al., In a paper published in Tetrahedron Letters 50, 1681, tried to react arylamine and trifluoroacetic acid directly by boiling xylene in a pyridine catalyst as a solvent. Considering that it boils around 140 degrees Celsius, there are still many problems that need to be improved.

As described above, conventional techniques for protecting nitrogen of amino acids so far known are methods for introducing trifluoroacetyl groups to amines or acetyl groups to amines. As described above, the reaction conditions of these processes are expensive. Not only are there problems such as high temperature violent conditions using the catalyst or a long reaction time, but also require the synthesis of another reagent to introduce these functional groups and the presence of acid-sensitive functional groups in the reaction. It is difficult to commercialize due to problems such as by-products, lower yields, and difficulty in purification, which has led to the development of a new manufacturing process that can protect amine groups under mild reaction conditions at room temperature and room temperature. Has been demanded . Research has also been conducted in various ways to protect carboxylic acids, which are another important functional group of amino acids, in ester form or to increase reactivity. N-hydroxy succinimide esters have long been used to control amino acid, peptide, protein, amino acid, peptide, It has been used as a method of introducing a functional group protecting a carboxylic acid of a protein. Callahan et al. Synthesized carboxylic acid and N-hydroxysuccinimide in the presence of dicyclohexylcarbodiimide in order to synthesize N-hydroxysuccinimide ester derivatives in the literature published in Journal of American Chemical Society, Vol. 86, pp. 1839, 1964 to obtain the target compound. However, this reaction has a disadvantage in that it is difficult to remove dicyclohexylurea obtained as a by-product. Parameswaren synthesized N-hydroxysuccinimide ester derivatives by reacting carboxylic acid with bis (N-succinimidyl) -carbonate in the literature published in 1990, Organic Preparation and Procedures, Vol. 22, 119. However, the synthesis of the coupling reagent (N-succinimidyl) carbonate and then reacted with the carboxylic acid again has the disadvantage that the target compound must be synthesized in two steps. Pochlauer et al. Synthesized N-hydroxysuccinimide ester derivatives by heating carboxylic acid and N-hydroxysuccinimide at 40-50 ° C for 24 hours in the presence of chlorophosphate in the literature published in Tetrahedron Vol. 54, page 3489, 1998. In order to synthesize N-hydroxysuccinimide ester derivatives in Molecules Vol. 6, p. 47, 2001, Christensen reacted carboxylic acid with thionyl chloride under DMF catalyst, converted to acid chloride, and then reacted with N-hydroxysuccinimide for 12 hours at 40 ℃. N-hydroxysuccinimide ester derivatives were synthesized. However, this reaction also has a disadvantage that can be obtained by synthesizing the target compound from the carboxylic acid in two steps. Najera et al. Synthesized N-hydroxysuccinimide ester derivatives by reacting carboxylic acid with uronium salts derived from N-hydroxysuccin-imide and 1,3-dimethylpropyleneurea in 2002, published in Tetrahedron Letters 43, page 1661. However, this reaction also has the disadvantage of synthesizing the uronium salt as a coupling reagent and then reacting with the carboxylic acid again to synthesize the target compound in two steps. Wentland et al. Synthesized the target compound by carbonylation reaction of aryl triflate or aryl iodide in the presence of N-hydroxysuccinide and palladium catalyst in order to synthesize N-hydroxysuccinimide ester derivatives in 2003, published in Tetrahedron Letters 44, page 2477. It was. However, this reaction has a disadvantage in that N-hydroxysuccinimide ester derivative is obtained by heating at 70 ° C. for 17 hours in a carbon monoxide atmosphere. Giannis et al. (2004), published in Advanced Synthesis and Catalysis, Vol. 346, pp. 252, reacted aldehydes with N-hydroxysuccinimide in the presence of 1-hydroxy-1,2-benziodoxol-3 (1H) -one 1-oxide to N-hydroxysuccinimide ester. Derivatives were synthesized. In this reaction, however, the reaction mixture is refluxed for 2-3 hours using ethyl acetate as a solvent. As described above, conventional techniques for obtaining N-hydroxysuccinimide ester derivatives have been obtained by preparing a coupling reagent and reacting with carboxylic acid again to synthesize N-hydroxysuccinimide ester derivative as a target compound in two steps. These reactions have problems such as intense reaction conditions at high temperature or long time, and when acid-sensitive functional groups are present inside the reactants, byproducts may occur, resulting in lowered yields or difficulty in purification. As a result, the development of a new manufacturing process capable of introducing N-hydroxysuccinimido groups into carboxylic acids has long been required as a task in this field. After protecting the amine of an amino acid with a protecting group in a more advanced way of protecting and reactivity of the carboxylic acid, the carboxylic acid portion of the amino acid is then referred to as N-trifluoroacetoxy succinimide (abbreviated as TFA-NHS). ), The carboxylic acid moiety is transformed into the form of hydroxy succinimide ester, which greatly increases the reactivity, which was described by Zonnal Obshchei Khimii 45, No. 11, 2497, in 1975, by Ponomareva-Stepnaya, MA et al. There is a bar. On the other hand, T. Sudhakar Rao et al. Reported that in 2002, Tetrahedron Letters 43, 7793, reacted N-trifluoroacetoxy succinimide (TFA-NHS) with unprotected amino acids for both amines and carboxylic acids. It has been reported that modification of the carboxylic acid moiety to the imide ester form, i.e. to the carbonyl group with increased reactivity, may occur simultaneously. However, these methods also suffer from the problem of synthesizing and using N-trifluoroacetoxy succinimide (TFA-NHS) to protect or increase the reactivity of the carboxylic acid. Although N-trifluoroacetoxy succinimide (TFA-NHS) is such a useful compound, the synthetic methods known to date have been described using trifluoroacetic anhydride (CF ₃ CO-O-COCF ₃ ). Only methods for reacting with N-hydroxysuccinimide are known.

In 1980, SM Andreev et al. Reported that trifluoroacetic anhydride (CF ₃ CO-O-COCF ₃ ) was 1.2 to N-hydroxysuccinimide in a patent application filed in the former Soviet Union Patent Publication No. SU-747854. N-trifluoroacetoxy succinimide (TFA- NHS) is obtained using 2.0 mole times, but the low boiling point, high volatility and high corrosion of trifluoroacetic anhydride are not only handled in laboratory small systems. It was just a skill. Thus far, the method of synthesizing N-trifluoroacetoxy succinimide is a method of reacting trifluoroacetic anhydride (CF ₃ CO-O-COCF ₃ ) with N-hydroxysuccinimide. Only known is the urgent need for the development of new industrial methods.

As described above, the present inventors have a problem that the reaction conditions of the process for introducing an acetyl group or a trifluoroacetyl group to protect the amine group of an amino acid are a high temperature intense condition using an expensive catalyst or a long reaction time. In addition to this, the synthesis of another reagent is required to introduce these functional groups, and when acid-sensitive functional groups are present inside the reaction, unwanted by-products occur, resulting in poor yield and difficulty in purification. While careful attention has been given to the difficulty of commercialization, several problems faced by previous methods for protecting or increasing the reactivity of another important functional group of amino acids, carboxylic acids, including N-trifluoroacetoxy succinimide CAR using (TFA-NHS) A problem with previous methods of increasing the reactivity while protecting acids, namely trifluoroacetic anhydride (CF ₃ CO-O-COCF ₃ ), is reacted with N-hydroxysuccinimide to N-tri In the process of obtaining fluoroacetoxy succinimide (TFA-NHS) and reacting with a carboxylic acid of an amino acid to convert the carboxylic acid into a hydroxy imide ester to protect, this method is known as trifluoroacetic anhydride. Because of its low boiling point and high volatility as well as its high corrosiveness, it is only a technique that can be handled in a laboratory small-scale system, and the next step is to synthesize N-trifluoroacetoxy succinimide (TFA-NHS). Pay close attention to the problems, such as the two-step reaction that must be proceeded to Efforts have been made to develop a desirable method to enhance the reactivity while protecting the acid, resulting in the direct reaction of N-hydroxy succinimide with trifluoroacetic acid and amino acids to protect the nitrogen of the amino acid with a trifluoroacetyl group. At the same time, the present invention has been completed by developing a preferable method which can increase the reactivity while protecting and converting the carboxylic acid of the amino acid into the hydroxy imide ester form.

The present invention is a method that plays an important role in synthesizing more useful substances by protecting the nitrogen functional group and increasing the reactivity of the carboxyl group in the synthesis of key intermediates in the field of fine chemicals such as peptide synthesis and pharmaceuticals or pesticides. The present invention relates to a novel process for obtaining an amino acid derivative that protects an amine, protects a carboxyl group, and enhances reactivity by protecting a trifluoroacetyl group and simultaneously converting a carboxyl group into a state of increased hydroxy succinimide ester reactivity. A method of reacting hydroxy succinimide with trifluoroacetic acid and amino acids directly, wherein the amino acid is reacted with N-hydroxy succinimide, trifluoroacetic acid in the presence of trichloromethylchloroformate and triethylamine, and at room temperature. Mildness A method for synthesizing by reacting at a reaction temperature condition. The present inventors introduced trifluoroacetyl groups into amino acid nitrogen under mild reaction conditions at normal pressure and near room temperature to protect amine groups while converting and protecting the carboxyl groups of the amino acid into hydroxy succinimide ester form while increasing the reactivity of the carboxyl groups. Efforts have been made to obtain derivatives. While trying to establish conditions under which trifluoroacetic acid can be activated to react with N-hydroxy succinimide and amino acids to obtain the desired compound, The trichloromethylchloroformate of) is activated by trifluoroacetic acid at a gentle reaction temperature of about 0 degrees Celsius to about room temperature to react directly with N-hydroxy succinimide and amino acid of the following formula (III) The nitrogen of the amino acid of I) is protected with a trifluoroacetyl group and carboxyl It has been found that the acid can easily obtain an amino acid derivative converted to the hydroxy imide ester form to complete the present invention.

In Formula (I), L represents a portion excluding amino group (-NH ₂ ) and carboxyl group (-COOH) from amino acids Alanine, Glycine, Isoleucine, Leucine, Methionine, Phenylalanine, Tryptophan, Valine and Histidine.

In the present invention, the following chemical structure (II) used as an activation reagent of trifluoroacetic acid

Trichloromethylchloroformate is used as a hygroscopic agent for synthesizing nitrile derivatives from amide derivatives, as Mai et al., Published on page 2203 of Tetrahedron Letters 27, 20, 1986, or Seeger et al. In 1996, J. Org. Chem. A reagent mainly used for synthesizing isocyanate derivatives from amines, as disclosed on pages 61 and 3883, by activating trifluoroacetic acid and reacting with N-hydroxy succinimide and amino acids, the amino group of the amino acid is N-trifluoroacetyl A reagent for synthesizing amino acids derivatives that converts carboxylic acids to hydroxy succinimide esters while protecting with groups and enhances protection and reactivity was first identified and developed by the present inventors.

The reaction conditions of the process for introducing an acetyl group or trifluoroacetyl group to protect the amine group of the amino acid are not only disadvantageous such as high temperature violent conditions using an expensive catalyst or long reaction time, but also such functional groups It was difficult to commercialize due to problems such as the synthesis of another reagent to be introduced and the presence of acid-sensitive functional groups present inside the reactants, resulting in undesired by-products, reduced yields, and difficulty in purification. As described above, N-trifluoroacetoxy succinimide (TFA-NHS), which is another important functional group of amino acids, protects carboxylic acids and enhances reactivity, among other problems. Increase reactivity while protecting carboxylic acids Key issues in the previous method to hold, that is, trifluoroacetic acetic anhydride _{(CF 3 CO-O-COCF} 3) of N- hydroxy succinimide in the acetoxy-N- trifluoro-imide by reaction with succinimide In the process of obtaining (TFA-NHS) and reacting with the carboxylic acid of the amino acid to convert the carboxylic acid into the hydroxy imide ester form, the method may be low in boiling point and highly volatile of the trifluoroacetic anhydride. In addition, it is highly corrosive and is only a technology that can be handled in a laboratory small-scale system, and a two-step reaction that requires the synthesis of N-trifluoroacetoxy succinimide (TFA-NHS) and proceeds to the next step. The present invention, which can solve various problems, such as a disadvantage, increases the reactivity while protecting the amine group of the amino acid and also protects the carboxylic acid of the amino acid. As a preferred method, N-hydroxy succinimide can be directly reacted with trifluoroacetic acid and amino acid to provide a new manufacturing process that can be synthesized in one step. In addition, by completing the present invention which can prepare the desired amino acid derivative under normal pressure and mild reaction conditions near room temperature, the manufacturing process conditions have secured a synthesis method excellent in the reliability and reproducibility of the reaction, and the present invention is applied to industrialization. Compared to the previous method, the reaction step and process time can be drastically reduced, and the separation and purification of the target compound can be easily performed without causing environmental problems by by-products.

 In the present invention, trichloromethylchloroformate of formula (II) is reacted with N-hydroxy succinimide of formula (III) by activating trifluoroacetic acid at a gentle reaction temperature at about 0 degrees Celsius to room temperature. Then, by directly reacting with the amino acid, the amine group of the amino acid of the following formula (I) is protected with a trifluoroacetyl group, and the carboxyl group of the amino acid is converted into the hydroxy succinimide ester form to easily obtain an amino acid derivative having enhanced reactivity. Provide a new way.

In Formula (I), L represents a portion excluding amino group (-NH ₂ ) and carboxyl group (-COOH) from amino acids Alanine, Glycine, Isoleucine, Leucine, Methionine, Phenylalanine, Tryptophan, Valine and Histidine.

 The specific chemical structure of the general formula (I) is as follows.

The present invention is not limited to the amino acid, which is a basic structural unit of proteins constituting the body of animals including humans, and is generally used as a compound having an amine group (-NH ₂ ) and a carboxyl group, for example, p- It is also applicable to compounds of the same kind as aminobenzoic acid. The present invention is a method for protecting the amine group and carboxyl group of a new amino acid which is simple in the whole synthesis process and reacts under mild conditions of about 0 degrees Celsius at atmospheric pressure and hardly generates by-products.

Trifluoroacetic acid used in the present invention is used 2 to 10 mole times, preferably 2.0 to 4.0 mole times compared to amino acids, trichloromethyl chloroformate is 1.0 to 5 mole times, preferably 1.5 to 3.0 mole times compared to amino acids Triethylamine is used in an amount of 3.0 to 15 mole times compared to amino acid. Instead of triethylamine, arylamines such as pyridine, N, N-dimethylaniline, or general tertiary amines can be used. The reaction temperature is reacted at 0 to 35 ^o C, preferably 0 to 25 ^o C. As the reaction solvent, all common organic solvents such as chloroform, dichloromethane and toluene can be used. Referring to the reaction sequence constituting the present invention is as follows.

First, trifluoroacetic acid was dissolved in dichloromethane as a solvent, cooled to 0 ^o C in an ice-bath, then trichloromethylchloroformate was added to the solution, stirred for about 5 minutes, and triethylamine was added at the same temperature. N-hydroxy succinimide was added and stirred for about 10 minutes. Finally, amino acid was added and the ice-bath was removed to naturally warm to room temperature, and 30 minutes to 2 hours, preferably 30 minutes to 1 hour. After stirring, the reaction was completed and can be confirmed by TLC.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the methods presented in the Examples.

Into a 30 mL flask, 342 mg (3.00 mmole) of trifluoroacetic acid and 15 mL of dichloromethane were added to a 30 mL flask, and cooled to 0-5 ^° C. in an ice-bath. And stir for 5 minutes. 1.063 g (10.5 mmole) of triethylamine was added thereto, and after about 5 minutes, 345 mg (3.00 mmole) of N-hydroxy succinimide was added thereto and stirred for about 20 minutes in an ice-bath. 89.0 mg (1.00 mmole) of amino acid Alanine was added thereto, the ice-bath was removed, and the mixture was naturally heated to room temperature and stirred. After about 30 minutes, the reaction was completed by TLC. After completion of the reaction, the reaction mixture was filtered through a silica gel filter to remove inorganic substances from the bottom, and the resulting solution was removed under reduced pressure to protect the amine group as a target compound with an N-trifluoroacetyl group, and the carboxyl group was in the form of N-hydroxy succinimide. 248 mg of protected Alanine derivative was obtained (yield 88.0%).

342 mg (3.00 mmole) of trifluoroacetic acid and 15 mL of chloroform were added to a 30 mL flask under nitrogen atmosphere, cooled to 0-5 ^° C. in an ice-bath, and 595 mg (3.00 mmole) of trichloromethylchloroformate was added thereto. Stir for 5 minutes. 1.518 g (15.0 mmole) of triethylamine was added thereto, and after about 5 minutes, 460 mg (4.00 mmole) of N-hydroxy succinimide was added thereto and stirred for about 20 minutes in an ice-bath. 149.0 mg (1.00 mmole) of amino acid Methionine was added thereto, the ice-bath was removed, and the mixture was naturally heated to room temperature and stirred. After about 30 minutes, the reaction was completed by TLC. After completion of the reaction, the reaction mixture was filtered through a silica gel filter to remove inorganic substances from the bottom, and the resulting solution was removed under reduced pressure to protect the amine group as a target compound with an N-trifluoroacetyl group, and the carboxyl group was in the form of N-hydroxy succinimide. 308 mg of protected Methionine derivative was obtained (yield 90.0%).

342 mg (3.00 mmole) of trifluoroacetic acid and 15 mL of dichloromethane were added to a 30 mL flask under nitrogen atmosphere, cooled to 0-5 ^° C. in an ice-bath, and 595 mg (3.00 mmole) of trichloromethylchloroformate was added thereto. And stir for 5 minutes. 1.063 g (10.5 mmole) of triethylamine was added thereto, and after about 5 minutes, 345 mg (3.00 mmole) of N-hydroxy succinimide was added thereto and stirred for about 20 minutes in an ice-bath. 165.0 mg (1.00 mmole) of amino acid Phenylalanine was added thereto, the ice-bath was removed, and the mixture was naturally heated to room temperature and stirred. After about 30 minutes, the reaction was completed by TLC. After completion of the reaction, the reaction mixture was filtered through a silica gel filter to remove inorganic substances from the bottom, and the resulting solution was removed under reduced pressure to protect the amine group as a target compound with an N-trifluoroacetyl group, and the carboxyl group was in the form of N-hydroxy succinimide. 312 mg of Phenyllanine derivative protected with (yield 87.0%) was obtained.

342 mg (3.00 mmole) of trifluoroacetic acid and 15 mL of dichloromethane were added to a 30 mL flask under nitrogen atmosphere, cooled to 0-5 ^° C. in an ice-bath, and 595 mg (3.00 mmole) of trichloromethylchloroformate was added thereto. And stir for 5 minutes. 1.063 g (10.5 mmole) of triethylamine was added thereto, and after about 5 minutes, 345 mg (3.00 mmole) of N-hydroxy succinimide was added thereto and stirred for about 20 minutes in an ice-bath. 131.0 mg (1.00 mmole) of amino acid Leucine was added thereto, the ice-bath was removed, and the mixture was naturally heated to room temperature and stirred. After about 30 minutes, the reaction was completed by TLC. After completion of the reaction, the reaction mixture was filtered through a silica gel filter to remove inorganic substances from the bottom, and the resulting solution was removed under reduced pressure to protect the amine group as a target compound with an N-trifluoroacetyl group, and the carboxyl group was in the form of N-hydroxy succinimide. 276 mg of Leucine derivative protected with (yield 85.0%) was obtained.

342 mg (3.00 mmole) of trifluoroacetic acid and 15 mL of chloroform were added to a 30 mL flask under nitrogen atmosphere, cooled to 0-5 ^° C. in an ice-bath, and 595 mg (3.00 mmole) of trichloromethylchloroformate was added thereto. Stir for 5 minutes. 1.063 g (10.5 mmole) of triethylamine was added thereto, and after about 5 minutes, 345 mg (3.00 mmole) of N-hydroxy succinimide was added thereto and stirred for about 20 minutes in an ice-bath. 117.0 mg (1.00 mmole) of amino acid Valine was added thereto, the ice bath was removed, and the mixture was naturally heated to room temperature and stirred. After about 30 minutes, the reaction was completed by TLC. After completion of the reaction, the reaction mixture was filtered through a silica gel filter to remove inorganic substances from the bottom, and the resulting solution was removed under reduced pressure to protect the amine group as a target compound with an N-trifluoroacetyl group, and the carboxyl group was in the form of N-hydroxy succinimide. 282 mg of Valine derivative protected with was obtained (yield 91.0%).

Claims (1)

N-hydroxy succinimide represented by the following formula (III) is reacted with trifluoroacetic acid (CF ₃ COOH) in the presence of trichloromethylchloroformate and triethylamine of the following formula (II), and finally A method for producing an amino acid derivative in which the amine group represented by the following general formula (I) is protected by a trifluoroacetyl group, and the carboxyl group is protected in the form of a hydroxy imide ester.

In Formula (I), L represents a portion excluding amino group (-NH ₂ ) and carboxyl group (-COOH) from amino acids Alanine, Glycine, Isoleucine, Leucine, Methionine, Phenylalanine, Tryptophan, Valine and Histidine.