Oxygen isotope labeled compound and method for producing oxygen isotope labeled compound

Abstract

To provide a novel oxygen isotope-labeled compound useful as a starting reagent for oxygen isotope labeled α-amino acid equivalents.SOLUTION: An oxygen isotope-labeled compound represented by the following (formula 1) and (formula 2) is selected. In the (formula 1) and (formula 2), Y is 18O or 17O, R1 is a C1-2 alkyl group, and R2's are the same or different to represent one of hydrogen, deuterium, a C1-2 alkyl group, a C1-2 alkoxy group, and a halogen atom.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an oxygen isotope-labeled compound and a method for producing an oxygen isotope-labeled compound. [Background technology]

[0002] Natural oxygen isotopes are 16 O is 99.759 atom%, 17 O is 0.037 atom%, 18 O is present at a ratio of 0.204 atom%. Of these oxygen isotopes, the heavy isotopes 18 Isotopically labeled compounds deoxygenated with O are useful in the fields of medicine, agrochemicals, and biochemistry as internal standards for quantitative analysis by mass spectrometry. 18 The percentage of O (atom%) is called "oxygen isotope ( 18 O) enrichment or simply "oxygen isotope enrichment."

[0003] Deuterium is often used as such a stable isotope element, but there are issues such as the difficulty of deuterium substitution in some compounds, and the insufficient number of isotope labels with deuterium substitution alone. In addition, the adverse effects of isotope effects have also been pointed out. For this reason, oxygen isotopes have been increasingly used in recent years. 18 The use of O as a label has attracted attention.

[0004] Oxygen, like carbon and nitrogen, has a larger mass number than hydrogen, so the physicochemical properties of the labeled form are closer to those of the unlabeled form; 18 If O is used, the mass number per label increases by two; 13 C and nitrogen isotopes 15 Despite its great advantages, such as being cheaper than N, it is rarely used in practice. The reason for this is that there are extremely few types of oxygen isotope compounds available commercially compared to deuterium-labeled compounds, carbon isotope-labeled compounds, and nitrogen isotope-labeled compounds. 18 When introducing16 It is essential to set strict reaction conditions that are not affected by water.

[0005] Since there are very few commercially available oxygen isotope-labeled reagents and the types are limited, it is desirable to provide oxygen isotope-labeled reagents that can follow known reaction conditions that are commonly used. The ability to apply known reaction conditions has the great advantage of simplifying preliminary studies.

[0006] Among oxygen isotope-labeled reagents, oxygen isotope-labeled amino acids are used in proteome analysis of proteins, and are used as a method of introducing oxygen isotope-labeled amino acids as internal standards into protein or peptide samples and performing mass spectrometry.

[0007] As a method for oxygen isotope labeling of amino acids having a carboxyl group, Non-Patent Document 1 describes the H2 18 A method has been disclosed in which an amino acid is reacted under strong acidic conditions in which O is saturated with hydrogen chloride gas, thereby exchanging the oxygen atom in the carboxyl group with an oxygen isotope.

[0008] However, there was a problem that the exchange reaction of the carboxyl group in the amino acid skeleton under acidic conditions caused decomposition reactions of amino acids such as tryptophan, cysteine, asparagine, and glutamine.

[0009] On the other hand, a glycine ester benzophenone Schiff base compound can be reacted with a specific organic compound in the presence of a catalyst and a basic compound to obtain a desired α-amino acid equivalent. Therefore, the glycine ester benzophenone Schiff base compound is a useful compound that can be used as a raw material for the synthesis of various α-amino acids such as asparagine and glutamine (Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] E. Ponnusany, CR Jones, D. Fiat, Journal of Labeled Compounds and Radiopharmaceuticals, 14, 7, (1986) [Non-Patent Document 2] MJO'Donnell, Aldrichimica Acta, 34, 1, (2001) Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in consideration of the above circumstances, and an objective of the present invention is to provide a novel oxygen isotope-labeled compound that is useful as a raw material reagent for oxygen isotope-labeled α-amino acid equivalents, and a method for producing the same. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention has the following configuration. [1] An oxygen isotope-labeled compound shown in the following formula (1). [ka] In the above formula (1), Y is 18 O or 17 O and R 1 is an alkyl group having 1 to 2 carbon atoms. [2] The oxygen isotope-labeled compound according to [1], wherein the enrichment of the oxygen isotope represented by Y exceeds its natural abundance. [3] An oxygen isotope-labeled compound shown in the following formula (2). [ka] In the above formula (2), Y is 18 O or 17 O and R 1 is an alkyl group having 1 to 2 carbon atoms, and R 2 are the same or different and are any of hydrogen, deuterium, an alkyl group having 1 to 2 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, and a halogen atom; and n is any of 1 to 5. [4] The oxygen isotope-labeled compound according to [3], wherein the enrichment of the oxygen isotope represented by Y exceeds its natural abundance. [5] A method for producing an oxygen isotope-labeled compound according to [1] or [2], comprising the steps of: A method for producing an oxygen isotope-labeled compound, comprising reacting a compound represented by the following formula (3) with potassium phthalimide: [ka] In the above formula (3), Y is 18 O or 17 O and R 1 is an alkyl group having 1 to 2 carbon atoms, and X is a halogen atom. [6] A method for producing an oxygen isotope-labeled compound according to [3] or [4], comprising the steps of: A compound represented by the following formula (3) is reacted with potassium phthalimide to obtain a compound represented by the following formula (1): The resulting compound represented by the following formula (1) is reacted with the compound represented by the following formula (4), and then the resulting mixture is reacted with a hydrogen chloride-1,4-dioxane solution and then with benzophenone imine to produce an oxygen isotope-labeled compound. [ka] [ka] [ka] In the above formula (1) and formula (3), Y is 18 O or 17 O and R 1 is an alkyl group having 1 to 2 carbon atoms, and X is a halogen atom. In addition, in the above formula (4), Z is hydrogen or a methyl group. Effect of the Invention

[0013] The oxygen isotope-labeled compounds of the present invention are novel compounds (oxygen isotope-labeled glycine ester benzophenone Schiff base compounds and oxygen isotope-labeled phthalimidoacetic ester compounds, which are the raw materials thereof) that are useful as raw material reagents for oxygen isotope-labeled α-amino acid equivalents. The method for producing an oxygen isotope-labeled compound of the present invention can produce the novel compound described above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Oxygen isotope labeled compounds> The oxygen isotope-labeled compound of the present invention is an oxygen isotope-labeled phthalimidoacetic acid ester compound represented by the following formula (1), and an oxygen isotope-labeled glycine ester benzophenone Schiff base compound represented by the following formula (2).

[0015] [ka]

[0016] [ka]

[0017] In the above formula (1) and the above formula (2), Y is 18 O or 17 O and R 1 is an alkyl group having 1 to 2 carbon atoms, and R 2 are the same or different and are any of hydrogen, deuterium, an alkyl group having 1 to 2 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, and a halogen atom; and n is any of 1 to 5.

[0018] In the oxygen isotope-labeled compound of the present invention, the enrichment (abundance ratio) of the oxygen isotope represented by Y in the above formula (1) and formula (2) preferably exceeds the natural abundance ratio of 0.204 atom%, and more preferably is 85 atom% or more. In other words, since the oxygen isotope-labeled compound of the present invention is used as a raw material reagent for oxygen isotope-labeled α-amino acid equivalents, the closer the enrichment is to 100 atom%, the more preferable it is.

[0019] The isotopic enrichment of the oxygen isotope target compound of the present invention can be calculated using a peak area value in EI-MS (electron ionization mass spectrometry) by the same calculation method as in Example 2 described in JP-A-2006-008666.

[0020] <Method for producing oxygen isotope-labeled compounds> [Method for producing oxygen isotope-labeled phthalimidoacetic acid ester compound] The method for producing the oxygen isotope-labeled phthalimide acetic acid ester compound represented by the above formula (1) comprises reacting a compound represented by the following formula (3) with potassium phthalimide.

[0021] [ka]

[0022] In the above formula (3), Y is 18 O or 17 O and R 1 is an alkyl group having 1 to 2 carbon atoms, and X is a halogen atom (F, Cl, Br, I).

[0023] Specifically, in the method for producing an oxygen isotope-labeled compound of the present invention, the compound represented by the above formula (3) is reacted with potassium phthalimide in an organic solvent. After the reaction is completed, distilled water is added to the reaction solution, and the precipitated powder represented by the above formula (1) is separated from the solvent by filtration. This results in the oxygen isotope-labeled phthalimide acetic acid ester compound represented by the above formula (1) being obtained (isolated).

[0024] In the method for producing an oxygen isotope-labeled compound of the present invention, the oxygen isotope represented by Y in the above formula (3) ( 18 O or 17 The enrichment (abundance ratio) of O) preferably exceeds the natural abundance ratio, more preferably is 90 atom % or more, and even more preferably is 95 atom % or more.

[0025] The organic solvent used in the reaction of the compound represented by the formula (3) with potassium phthalimide is not particularly limited, and examples of such organic solvent include alcohols such as methanol and ethanol.

[0026] The amount of the compound represented by the above formula (3) used relative to potassium phthalimide is preferably stoichiometric or more. The upper limit of the amount of the compound represented by the above formula (3) used is not particularly limited, but in order to avoid an increase in cost due to excessive use, it is preferably 1.03 equivalents or less, more preferably 1.01 equivalents or less.

[0027] The reaction temperature of the compound represented by the above formula (3) with potassium phthalimide is in the range of 0 to 100° C., and preferably in the range of 40 to 60° C. If the reaction temperature is lower than 0° C., the reaction does not proceed, which is undesirable, and if it is higher than 100° C., the raw materials and the product may decompose, which is undesirable.

[0028] The reaction time of the compound represented by the formula (3) with potassium phthalimide is 30 minutes or more. If the reaction time is less than 30 minutes, the reaction does not finish completely, which is not preferable.

[0029] [Method for producing oxygen isotope-labeled glycine ester benzophenone Schiff base compound] The method for producing the oxygen isotope-labeled glycine ester benzophenone Schiff base compound represented by the above formula (2) is to react the oxygen isotope-labeled phthalimidoacetic ester compound represented by the above formula (1) with the compound represented by the following formula (4), then react with hydrogen chloride-1,4-dioxane solution, and then react with benzophenone imine.

[0030] [ka]

[0031] In the above formula (4), Z is hydrogen or a methyl group.

[0032] Specifically, in the method for producing an oxygen isotope-labeled compound of the present invention, first, the compound of the above formula (1) (oxygen isotope-labeled phthalimidoacetic ester compound) is reacted with the compound shown in the above formula (4) in an organic solvent to produce an oxygen isotope-labeled glycine ester in the system. The organic solvent is then removed under reduced pressure, and a solution of hydrogen chloride in 1,4-dioxane is added to give the oxygen isotope-labeled glycine ester hydrochloride, after which the solvent is removed under reduced pressure. Next, benzophenone imine and an organic solvent are added to this reaction system, and the reaction is allowed to proceed with oxygen isotope-labeled glycine ester hydrochloride, after which the product is isolated and purified using column chromatography. As a result, the oxygen isotope-labeled glycine ester benzophenone Schiff base represented by the above formula (2) is obtained.

[0033] The organic solvent used in the reaction of the compound represented by the formula (1) with the compound represented by the formula (4) is not particularly limited. Examples of such organic solvent include alcohols such as methanol and ethanol.

[0034] The amount of the compound represented by the formula (4) used relative to the compound represented by the formula (1) may be a small stoichiometric excess, preferably 1.1 to 1.3 equivalents. By using a small stoichiometric excess, decomposition of the compound can be suppressed.

[0035] The reaction time of the compound represented by the formula (1) and the compound represented by the formula (4) is preferably 1 to 3 hours. If the reaction time is less than 1 hour, the reaction does not proceed, which is not preferable. On the other hand, if the reaction time exceeds 3 hours, the generated oxygen isotope-labeled glycine ester is decomposed, which is not preferable.

[0036] The reaction between the compound represented by the formula (1) and the compound represented by the formula (4) is preferably carried out under ice-cooling. If the reaction temperature is higher than room temperature, it is not preferable because it leads to decomposition of the oxygen isotope-labeled glycine ester.

[0037] The amount of the hydrogen chloride·1,4-dioxane solution used is preferably such that the amount of hydrogen chloride is in stoichiometric excess over the compound represented by the above formula (1).

[0038] The reaction should be carried out under ice cooling when adding the hydrogen chloride·1,4-dioxane solution to the reaction system. If the reaction temperature is higher than room temperature, it will lead to the decomposition of the oxygen isotope-labeled glycine ester, which is not recommended.

[0039] The solvent used in the reaction with benzophenone imine is not particularly limited. Examples of such a solvent include dichloromethane and chloroform, and among these, dichloromethane is preferably used.

[0040] The amount of benzophenone imine used is preferably a stoichiometric equivalent amount to the compound represented by the above formula (1).

[0041] In the reaction with benzophenone imine, the reaction temperature is not particularly limited, but is preferably 0 to 50° C. Furthermore, the reaction time is not particularly limited, but is preferably 12 to 24 hours.

[0042] As explained above, the oxygen isotope-labeled compound of the present invention is a novel compound. The oxygen isotope-labeled glycine ester benzophenone Schiff base compound of the present invention is useful as a raw material reagent for oxygen isotope-labeled α-amino acid equivalents. The oxygen isotope-labeled phthalimidoacetic ester compound of the present invention is a raw material for the above-mentioned oxygen isotope-labeled glycine ester benzophenone Schiff base compound. The method for producing an oxygen isotope-labeled compound of the present invention can produce the novel compound described above.

[0043] The present invention is not limited to such specific embodiments, and the present invention may be modified in various ways, such as by adding, omitting, substituting, or otherwise modifying the configuration, within the scope of the spirit of the present invention as defined in the claims. EXAMPLES

[0044] The effects of the present invention will be described in detail below with reference to examples. However, the present invention is not limited to the contents of the following examples.

[0045] Example 1 The reaction shown in the following formula (5) produces methyl phthalimidoacetate- 18 O was synthesized.

[0046] [ka]

[0047] Specifically, 10 mL of methyl bromoacetate was added to a recovery flask. 18 2.58 g (16.4 mmol) of 2O was collected, 10 mL of N,N-dimethylformamide was added and stirred, 3.06 g (16.5 mmol) of potassium phthalimide was added, and the reaction was carried out overnight at 50° C. After the reaction, the liquid was separated, the solvent was distilled off under reduced pressure, and methyl phthalimide acetate was obtained. 18 O was obtained (3.30 g, yield 91%, enrichment 98.0 atom%) 18 O).

[0048] Example 2 Glycine methyl ester benzophenone Schiff base- 18 O was synthesized.

[0049] [ka]

[0050] Specifically, 50 mL of methyl phthalimidoacetate was added to a 50 mL eggplant flask. 180.44g (2mmol) of 2O and 20mL of ethanol were added and stirred under ice cooling, then 4.4mL (4.4mmol) of 1M methylhydrazine-ethanol solution was added and reacted under ice cooling for 2 hours, and the solvent was distilled off under reduced pressure. 20mL of ethanol and 2mL of 4M hydrogen chloride-1,4-dioxane solution were added to this reaction system under ice cooling and stirred, and the solvent was distilled off again under reduced pressure. 10mL of dichloromethane and 0.34mL (2mmol) of benzophenone imine were added to the obtained powder and stirred for 24 hours. After the reaction, the reaction solution was filtered, the solvent was distilled off under reduced pressure, and the mixture was purified by column chromatography to obtain glycine methyl ester benzophenone Schiff base- 18 O was obtained (0.09 g, yield 18%, enrichment 89.8 atom%) 18 O).

[0051] Example 3 The reaction shown in the following formula (7) produces ethyl phthalimide acetate- 18 O was synthesized.

[0052] [ka]

[0053] Specifically, in a 10 mL eggplant flask, 18 3.00 g (17.8 mmol) of O was collected, 9 mL of N,N-dimethylformamide was added and stirred, then 3.32 g (17.9 mmol) of potassium phthalimide was added and reacted overnight at 50° C. After the reaction, the liquid was separated, the solvent was distilled off under reduced pressure, and ethyl phthalimide acetate- 18 O was obtained (3.87 g, yield 93%, enrichment 97.3 atom% 18 O).

[0054] Example 4 Glycine ethyl ester benzophenone Schiff base- 18 O was synthesized.

[0055] [ka]

[0056] Specifically, in a 50 mL eggplant flask, 18 0.47g (2mmol) of 2O and 20mL of ethanol were added and stirred under ice cooling, then 4.4mL (4.4mmol) of 1M methylhydrazine-ethanol solution was added and reacted under ice cooling for 2 hours, and the solvent was distilled off under reduced pressure. 20mL of ethanol and 2mL of 4M hydrogen chloride-1,4-dioxane solution were added to this reaction system under ice cooling and stirred, and the solvent was distilled off again under reduced pressure. 10mL of dichloromethane and 0.34mL (2mmol) of benzophenone imine were added to the obtained powder and stirred at room temperature for 24 hours. After the reaction, the reaction solution was filtered, the solvent was distilled off under reduced pressure, and the mixture was purified by column chromatography to obtain glycine ethyl ester benzophenone Schiff base- 18 O was obtained (0.11 g, yield 20%, enrichment 91.2 atom%) 18 O). [Industrial Applicability]

[0057] The oxygen isotope-labeled compound and the method for producing an oxygen isotope-labeled compound of the present invention have industrial applicability as an oxygen isotope-labeled compound for synthesizing an oxygen isotope-labeled α-amino acid equivalent and an oxygen isotope-labeled compound that is a synthetic intermediate thereof.

Claims

1. An oxygen isotope-labeled compound represented by the following formula (1). 【Chemistry 1】 In the above formula (1), Y is １８ O or １７ O and R １ is an alkyl group having 1 to 2 carbon atoms.

2. 2. The oxygen isotope labeled compound of claim 1, wherein the enrichment of the oxygen isotope represented by Y exceeds its natural abundance.

3. An oxygen isotope-labeled compound represented by the following formula (2). 【Chemistry 2】 In the above formula (2), Y is １８ O or １７ O and R １ is an alkyl group having 1 to 2 carbon atoms, R ２ are the same or different and are any of hydrogen, deuterium, an alkyl group having 1 to 2 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, and a halogen atom; and n is an integer of 1 to 5.

4. The oxygen isotope-labeled compound according to claim 3 , wherein the enrichment of the oxygen isotope represented by Y exceeds its natural abundance.

5. A method for producing the oxygen isotope-labeled compound according to claim 1 or 2, comprising the steps of: A method for producing an oxygen isotope-labeled compound, comprising reacting a compound represented by the following formula (3) with potassium phthalimide: 【Chemistry 3】 In the above formula (3), Y is １８ O or １７ O and R １ is an alkyl group having 1 to 2 carbon atoms, and X is a halogen atom.

6. A method for producing an oxygen isotope-labeled compound according to claim 3 or 4, comprising the steps of: A compound represented by the following formula (3) is reacted with potassium phthalimide to obtain a compound represented by the following formula (1): The resulting compound represented by the following formula (1) is reacted with a compound represented by the following formula (4), and then the resulting mixture is reacted with a hydrogen chloride / 1,4-dioxane solution and then with benzophenone imine, thereby producing an oxygen isotope-labeled compound. 【Chemistry 4】 【Chemistry 5】 【Chemistry 6】 In the above formula (1) and formula (3), Y is １８ O or １７ O and R １ is an alkyl group having 1 to 2 carbon atoms, and X is a halogen atom. In addition, in the above formula (4), Z is hydrogen or a methyl group.

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