Method for producing compound

Abstract

To provide a method for producing a compound capable of efficiently producing a compound having a peptide bond using a renewable condensation agent.SOLUTION: There is provided a method for producing a compound which comprises a step (I) of reacting a compound (A) having a carboxyl group derived from an amino acid and a compound (B) having an amino group derived from an amino acid in a reaction liquid containing a triarylphosphine having at least one electron-donating group on an aryl group to obtain a compound (C) having a peptide bond, wherein in the step (I), an electrode for oxidizing the triarylphosphine is disposed in the reaction solution and a voltage is applied to the electrode to react the compound (A) with the compound (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to methods for producing compounds having peptide bonds. [Background technology]

[0002] Solid-phase synthesis has long been known as a peptide synthesis technique, but it has drawbacks, such as the need for excessive amounts of reaction reagents and large amounts of solvent, making mass production difficult.

[0003] For this reason, liquid-phase peptide synthesis has been investigated in recent years. For example, Patent Document 1 discloses a method for liquid-phase peptide synthesis using a soluble tag as a carrier. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-183298 Summary of the Invention [Problem to be solved by the invention]

[0005] In peptide synthesis, peptide bonds are formed by a dehydration condensation reaction between the carbonyl and amino groups of amino acids. This requires the use of a stoichiometric amount of a condensing agent to activate the reaction, which creates a problem of generating non-recyclable waste after the reaction is complete.

[0006] An object of the present disclosure is to provide a method for producing a compound that can efficiently produce a compound having a peptide bond using a renewable condensing agent. [Means for solving the problem]

[0007] The present disclosure relates to, for example, the following [1] to [5]. [1] The method includes a step (I) of reacting a compound (A) having a carboxy group derived from an amino acid with a compound (B) having an amino group derived from an amino acid in a reaction solution containing a triarylphosphine having at least one electron-donating group on the aryl group to obtain a compound (C) having a peptide bond, In the step (I), an electrode for oxidizing the triarylphosphine is placed in the reaction solution, and a voltage is applied to the electrode to cause the compound (A) and the compound (B) to react with each other. Methods for producing compounds. [2] The production method according to [1], wherein the compound (B) has a solubilizing tag. [3] The method according to [1] or [2], wherein the electron-donating group is an alkoxy group. [4] The production method according to any one of [1] to [3], wherein the compound (A) and the compound (C) have amino groups protected by protecting groups. [5] a step (II) of reacting a compound (a) having a carboxy group derived from an amino acid and an amino group protected with a protecting group with a compound (b) having an amino group derived from an amino acid and a solubilizing tag to obtain a compound (c) having a peptide bond, an amino group protected with a protecting group, and a solubilizing tag; a deprotection step of deprotecting the compound (c) to obtain the compound (B); The method according to any one of [1] to [4], further comprising: [Effects of the Invention]

[0008] According to the present disclosure, a method for producing a compound is provided that can efficiently produce a compound having a peptide bond using a renewable condensing agent. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will be described in detail below.

[0010] The production method of this embodiment includes step (I) of reacting compound (A) having a carboxy group derived from an amino acid with compound (B) having an amino group derived from an amino acid in a reaction solution containing a triarylphosphine having at least one electron-donating group on the aryl group to obtain compound (C) having a peptide bond. In step (I), electrodes for oxidizing the triarylphosphine are placed in the reaction solution. In step (I), a voltage is applied to the electrodes to react compound (A) with compound (B).

[0011] In the production method of the present embodiment, an electrochemical technique is used, and a triarylphosphine having a specific substituent is used as a condensing agent, whereby the dehydration condensation reaction between compound (A) and compound (B) proceeds efficiently, and compound (C) having a peptide bond can be efficiently produced.

[0012] In this embodiment, triarylphosphine is oxidized by a voltage applied to the electrode to form a radical cation, and the radical cation reacts with the carboxy group of compound (A), causing a dehydration condensation reaction. Since triarylphosphine has a specific substituent, the reaction (side reaction) between the radical cation and water is suppressed, and the reaction between the radical cation and the carboxy group proceeds selectively. Therefore, it is believed that the production method of this embodiment can efficiently produce compound (C) having a peptide bond.

[0013] Furthermore, in this embodiment, triarylphosphine oxide, which is an oxide of triarylphosphine, is produced after the dehydration condensation reaction. This triarylphosphine oxide can be quantitatively recovered and can be reduced and reused as triarylphosphine. Therefore, the production method of this embodiment can reduce waste generated by the reaction.

[0014] (triarylphosphine) In this embodiment, the triarylphosphine has at least one electron donating group on the aryl group.

[0015] The aryl group may be, for example, a phenyl group. That is, the triarylphosphine may be, for example, a compound in which three phenyl groups are bonded to a phosphorus atom and at least one of the three phenyl groups has an electron-donating group.

[0016] The triarylphosphine preferably has an electron-donating group at the ortho- or para-position of the phenyl group bonded to the phosphorus atom, and more preferably has an electron-donating group at the para-position.

[0017] The triarylphosphine may have multiple electron-donating groups, for example, 1 to 3 electron-donating groups, or 2 or 3 electron-donating groups, or 3 electron-donating groups. The multiple electron-donating groups may be bonded to different aryl groups (for example, phenyl groups).

[0018] Examples of the electron-donating group include an alkyl group, an alkoxy group, a dialkylamino group, etc. The electron-donating group is preferably an alkyl group or an alkoxy group, and more preferably an alkoxy group.

[0019] The alkyl group may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a heptyl group, and a pentadecanyl group.

[0020] The alkoxy group may be, for example, an alkoxy group having 1 to 15 carbon atoms. The number of carbon atoms in the alkoxy group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkoxy group include a methoxy group, an ethoxy group, a heptoxy group, and a pentadecatoxy group.

[0021] The two alkyl groups in the dialkylamino group may be the same or different. The alkyl group in the dialkylamino group may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group in the dialkylamino group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group in the dialkylamino group include a methyl group, an ethyl group, a heptyl group, and a pentadecanyl group. Examples of the dialkylamino group include a dimethylamino group, a diethylamino group, a diheptylamino group, and a dipentadecanyl group.

[0022] The triarylphosphine may be, for example, a compound represented by the following formula (P-1).

[0023] [ka]

[0024] In formula (P-1), R 1 , R 2 , R 3 , R 4 , R 5 , R 11 , R 12 , R 13 , R 14 , R 15 , R 21 , R 22 , R 23 , R 24 and R 25 each independently represents a hydrogen atom or an electron-donating group. 1 , R 2 , R 3 , R 4 , R 5 , R 11 , R 12 , R 13 , R 14 , R 15 , R 21 , R 22 , R 23 , R 24 and R 25 At least one of these is an electron-donating group.

[0025] In formula (P-1), R 1 , R 3 , R 5 , R 11 , R 13 , R 15 , R 21 , R 23 and R 25 It is preferable that at least one of R is an electron-donating group. 3 , R 13 and R 23 It is more preferable that at least one of the groups is an electron-donating group.

[0026] When the triarylphosphine has two or three electron-donating groups, in formula (P-1), R 1 , R 3 , R 5 , R 11 , R 13 , R 15 , R 21 , R 23 and R 25 Preferably, two or three of R are electron-donating groups. 1 , R 3 and R 5 One of the following, and R 11 , R 13 and R 15 Preferably, one of R is an electron-donating group, 1 , R 3 and R 5 One of the R 11 , R 13 and R 15 One of these, and R 21 , R 23 and R 25 It is more preferred that one of the groups is an electron donating group.

[0027] In formula (P-1), R 3 , R 13 and R 23 Preferably, at least one of R is an electron-donating group. 3 , R 13 and R 23 It is more preferable that two or three of R are electron-donating groups.3 , R 13 and R 23 It is more preferred that all of are electron-donating groups.

[0028] In formula (P-1), R 2 , R 4 , R 12 , R 14 , R 22 and R 24 is preferably a hydrogen atom. 1 , R 5 , R 11 , R 15 , R 21 and R 25 may be a hydrogen atom.

[0029] (Compound (A)) Compound (A) has a carboxy group derived from an amino acid. An amino acid is a compound having an amino group and a carboxy group.

[0030] Compound (A) may be, for example, an amino acid or an amino acid derivative in which the amino group is protected with a protecting group. The amino acid derivative may be, for example, an amino acid having a functional group having an active hydrogen (e.g., another amino group, another carboxy group, a hydroxy group, an amide group, a thiol group, a guanidinyl group, an imidazole group, etc.) in addition to one amino group and one carboxy group, in which the functional group is protected with a protecting group or the active hydrogen of the functional group is substituted with an alkyl group or an aryl group.

[0031] The amino-protecting group is not particularly limited and may be appropriately selected from known protecting groups for protecting amino groups. Examples of the amino-protecting group include a 9-fluorenylmethyloxycarbonyl group (Fmoc group), a tert-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group (Cbz group), a 2-(trimethylsilyl)ethoxycarbonyl group (Teoc group), a 2,2,2-trichloroethoxycarbonyl group (Troc group), and an allyloxycarbonyl group (Alloc group).

[0032] The alkyl group that substitutes the active hydrogen of the amino group may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a heptyl group, and a pentadecanyl group.

[0033] The aryl group that substitutes for the active hydrogen of the amino group may be, for example, a phenyl group that may have a substituent. The substituent that the phenyl group may have may be, for example, an alkyl group, an alkoxy group, a dialkylamino group, etc., and the number of carbon atoms in the alkyl group in these groups may be, for example, the same as above.

[0034] The protecting group for the carboxy group is not particularly limited and may be appropriately selected from known protecting groups for protecting a carboxy group, such as a tert-butyl group, a trimethylsilylethoxy group, and a benzyl group.

[0035] The alkyl group that substitutes the active hydrogen of the carboxy group may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a tert-butyl group, a heptyl group, and a pentadecanyl group.

[0036] The aryl group that replaces the active hydrogen of the carboxyl group may be, for example, a phenyl group that may have a substituent. The substituent that the phenyl group may have may be, for example, an alkyl group, an alkoxy group, a dialkylamino group, etc., and the number of carbon atoms in the alkyl group in these groups may be, for example, the same as above.

[0037] The hydroxy-protecting group is not particularly limited and may be appropriately selected from known protecting groups for protecting hydroxy groups, such as tert-butyl, benzyl, trimethylsilyl, tert-butyldimethylsilyl, trityl, and acetyl groups.

[0038] The alkyl group that substitutes the active hydrogen of the hydroxy group may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a tert-butyl group, a heptyl group, and a pentadecanyl group.

[0039] The aryl group to be substituted with the active hydrogen of the hydroxy group may be, for example, a phenyl group which may have a substituent. The substituent that the phenyl group may have may be, for example, an alkyl group, an alkoxy group, a dialkylamino group, etc., and the number of carbon atoms in the alkyl group in these groups may be, for example, the same as above.

[0040] The protecting group for the amide group is not particularly limited and may be appropriately selected from known protecting groups for protecting an amide group, such as a trityl group and a monomethoxytrityl group.

[0041] Examples of the alkyl and aryl groups that substitute for the active hydrogen of the amide group include the same alkyl and aryl groups that substitute for the active hydrogen of the amino group.

[0042] The thiol-protecting group is not particularly limited and may be appropriately selected from known protecting groups for protecting thiol groups, such as tert-butyl, benzyl, trityl, acetamide, and monomethoxytrityl groups.

[0043] Examples of the alkyl and aryl groups that substitute for the active hydrogen of the thiol group include the same alkyl and aryl groups that substitute for the active hydrogen of the hydroxy group.

[0044] The protecting group for the guanidinyl group is not particularly limited and may be appropriately selected from known protecting groups for protecting a guanidinyl group, such as a tert-butoxycarbonyl group, a p-toluenesulfonyl group, and a 2,2,4,6,7-pentamethyl-2,3-dihydro-5-benzofuranyl (Pbf) group.

[0045] Examples of the alkyl and aryl groups that substitute for the active hydrogen of the guanidinyl group include the same alkyl and aryl groups that substitute for the active hydrogen of the amino group.

[0046] Examples of amino acids include glycine (Gly), alanine (Ala), isoleucine (Ile), leucine (Leu), valine (Val), methionine (Met), cysteine ​​(Cys), serine (Ser), threonine (Thr), aspartic acid (Asp), glutamic acid (Glu), asparagine (Asn), glutamine (Gln), phenylalanine (Phe), tyrosine (Tyr), arginine (Arg), lysine (Lys), histidine (His), tryptophan (Trp), proline (Pro), N-methylphenylalanine (NMePhe), N-methylalanine (NMeAla), N-methylvaline (NMeVal), N-methylleucine (NMeLeu), N-methylisoleucine (NMeILe), 2-aminoisobutyric acid (Aib), and sarcosine (Sar).

[0047] The compound (A) may be, for example, a compound represented by the following formula (A-1).

[0048] [ka]

[0049] In formula (A-1), PG represents a protecting group, and R A1 , R A2 and R A3 each independently represents a hydrogen atom or an alkyl group which may have a substituent, and R A1 and R A3 , or RA2 and R A3 may be bonded to each other to form a ring.

[0050] R A1 and R A2 The alkyl group in the formula (I) may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a cyclohexyl group, and a tert-butyl group.

[0051] R A1 and R A2 Examples of the substituent that the alkyl group may have include an aryl group, an alkoxy group, an alkyloxycarbonyl group, a hydroxy group, and a carboxy group.

[0052] The aryl group as a substituent includes, for example, a phenyl group which may have a substituent, such as an alkyl group, an alkoxy group, or a dialkylamino group.

[0053] The alkoxy group as a substituent may be, for example, an alkoxy group having 1 to 15 carbon atoms. The number of carbon atoms in the alkoxy group as a substituent may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkoxy group as a substituent include a methoxy group, an ethoxy group, a heptyl group, and a pentadecanyl group.

[0054] The alkyloxycarbonyl group as a substituent may have an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group in the alkyloxycarbonyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyloxycarbonyl group as a substituent include a tert-butyloxycarbonyl group and a cyclohexylcarbonyl group.

[0055] R A3The alkyl group in the formula (I) may be, for example, an alkyl group having 1 to 15 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 10, 1 to 7, or 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a heptyl group, and a pentadecanyl group.

[0056] R A3 Examples of the substituent that the alkyl group in R may have include an aryl group and an alkoxy group, and examples of these groups include the same groups as those described above. A3 The alkyl group in may be an unsubstituted alkyl group.

[0057] The protecting group for PG is not particularly limited and may be appropriately selected from known protecting groups for protecting amino groups. Preferred examples of the protecting group for PG include a 9-fluorenylmethyloxycarbonyl group (Fmoc group), a tert-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group (Cbz group), a 2-(trimethylsilyl)ethoxycarbonyl group (Teoc group), a 2,2,2-trichloroethoxycarbonyl group (Troc group), and an allyloxycarbonyl group (Alloc group).

[0058] (Compound (B)) Compound (B) has an amino group derived from an amino acid, which is a compound having an amino group and a carboxy group.

[0059] Compound (B) may be, for example, a group in which the —OH of the carboxy group of an amino acid or amino acid derivative is substituted with an inert group, as long as the inert group does not react with the radical cation generated in step (I).

[0060] The amino acid derivative may be, for example, a compound in which, in addition to one amino group and one carboxy group, an amino acid has a functional group having an active hydrogen (e.g., another amino group, another carboxy group, a hydroxy group, an amide group, a thiol group, a guanidinyl group, an imidazole group, etc.), the functional group is protected with a protecting group, or the active hydrogen of the functional group is substituted with an alkyl group or an aryl group.

[0061] Examples of the amino acid include the same amino acids as those described for compound (A).

[0062] Examples of the protecting group and the alkyl and aryl groups that substitute for the active hydrogen of the functional group include the same groups as those exemplified for compound (A).

[0063] Examples of the inert group include an alkoxy group and an aryloxy group.

[0064] The inert group is preferably a group having a solubilizing tag, such as a group represented by the following formula (X-1):

[0065] [ka]

[0066] In formula (X-1), T 1 represents a solubilization tag, R represents a group derived from an amino acid, and n 1 represents an integer of 0 or greater. When a plurality of R's are present, the plurality of R's may be the same or different.

[0067] R may be, for example, a divalent group obtained by removing the hydrogen atom of the amino group and the hydrogen atom of the carboxy group from an amino acid or an amino acid derivative. The amino acid derivative may be the same compound as the amino acid derivative described above.

[0068] R may be, for example, a group represented by the following formula (R-1).

[0069] [ka]

[0070] In formula (R-1), R A1 , R A2 and R A3 As for R in formula (A-1), A1 , RA2 and R A3 Examples include the same groups as those shown in the above.

[0071] In formula (X-1), R A1 , R A2 and R A3 If there are multiple R A1 may be the same or different, and multiple R A2 may be the same or different, and multiple R A3 may be the same or different from each other.

[0072] The solubilizing tag may be any group that is inert to the reaction in step (I) (i.e., does not react with the radical cation generated in step (I)) and that improves the solubility of compound (B) in a solvent.

[0073] The solubilizing tag may be, for example, a group represented by the following formula (T-1):

[0074] [ka]

[0075] In formula (T-1), X is —O—, —S—, or —NR 33 -, and R 31 represents an alkanediyl group or a carbonyl group, and R 32 represents a hydrocarbon group, and n 2 represents an integer of 1 to 3. 33 represents a hydrogen atom or an alkyl group.

[0076] R 31 The alkanediyl group in the formula (I) may be, for example, an alkanediyl group having 1 to 10 carbon atoms. The alkanediyl group may have 1 to 7, 1 to 5, or 1 to 3 carbon atoms.

[0077] R 32 The hydrocarbon group in may be, for example, an aliphatic hydrocarbon group, and may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group.

[0078] R 32 The number of carbon atoms in the hydrocarbon group in R may be, for example, 10 or more, 15 or more, or 20 or more. 32 The number of carbon atoms in the hydrocarbon group may be, for example, 40 or less, or 30 or less.

[0079] R 33 The alkyl group in the formula (I) may be, for example, an alkyl group having 1 to 40 carbon atoms. The number of carbon atoms in the alkyl group may be 1 to 30, 1 to 20, or 1 to 10. Examples of the alkyl group include a methyl group, an ethyl group, an octadecyl group, and a docosyl group.

[0080] n 2 is an integer of 1 to 3, preferably 2 or 3.

[0081] The compound (B) may be, for example, a compound represented by the following formula (B-1).

[0082] [ka]

[0083] In formula (B-1), R B1 , R B2 and R B3 each independently represents a hydrogen atom or an alkyl group which may have a substituent, and R B4 represents an inert group, and R B1 and R B3 , or R B2 and R B3 may be bonded to each other to form a ring.

[0084] R B1 and R B2 As for R A1 and R A2 The same idea can be exemplified.

[0085] R B3 As for R A3 Examples include the same groups as those shown in the above.

[0086] R B4 is preferably a group having a solubilizing tag. B4 may be, for example, a group represented by the above formula (X-1).

[0087] Compound (B) may be obtained by the step (II) and the deprotection step described below.

[0088] (Compound (C)) Compound (C) is a compound obtained by a dehydration condensation reaction between the carboxy group of compound (A) and the amino group of compound (B), and has a peptide bond formed by the dehydration condensation reaction.

[0089] Compound (C) may have the structure of compound (A) other than the carboxy group, or the structure of compound (B) other than the amino group. For example, when compound (A) has an amino group protected with a protecting group, compound (C) will have an amino group protected with a protecting group. Also, for example, when compound (B) has a solubilizing tag, compound (C) will have a solubilizing tag.

[0090] The compound (C) may be, for example, a compound represented by the following formula (C-1).

[0091] [ka]

[0092] In formula (C-1), PG and R A1 , R A2 and R A3 are PG and R in formula (A-1). A1 , R A2 and R A3 is synonymous with R B1 , R B2 , R B3 and R B4 is R in formula (B-1) B1 , R B2 , R B3 and R B4 is synonymous with.

[0093] The compound represented by formula (C-1) can be produced by reacting a compound represented by formula (A-1) with a compound represented by formula (B-1).

[0094] Compound (C) can be subjected to a dehydration condensation reaction as compound (B) in step (I) by deprotecting the protecting group on the amino group (e.g., PG in the compound represented by formula (C-1)). By repeating such deprotection and dehydration condensation reactions, a polypeptide in which any amino acid is linked can be easily produced.

[0095] (Process (I)) In the present embodiment, step (I) is a step of obtaining compound (C) by reacting compound (A) with compound (B) in a reaction solution containing the above-described triarylphosphine and in which an electrode for oxidizing the triarylphosphine is placed.

[0096] In step (I), triarylphosphine is oxidized by an electrode to generate a radical cation, which reacts with the carboxy group of compound (A), thereby causing a dehydration condensation reaction to proceed.

[0097] In step (I), the molar ratio (B / A) of compound (B) to compound (A) may be, for example, 0.05 or more, or may be 0.1 or more, 0.2 or more, or 0.3 or more. Furthermore, the molar ratio (B / A) may be, for example, 10 or less, or may be 5 or less, 3 or less, or 1 or less. When compound (B) has a solubilization tag, from the viewpoint of avoiding loss of compound (B) having the solubilization tag, the molar ratio (B / A) may be, for example, less than 1, or may be 0.9 or less, 0.8 or less, or 0.7 or less.

[0098] In step (I), the molar ratio (P / B) of triarylphosphine to compound (B) may be, for example, 0.8 or more, and from the viewpoint of increasing the proportion of compound (B) involved in the dehydration condensation reaction and allowing the reaction to proceed more efficiently, it may be 1 or more, 1.5 or more, or 2 or more. Moreover, the molar ratio (P / B) may be, for example, 10 or less, 7 or less, or 5 or less.

[0099] The solvent used in the reaction solution of step (I) may be any solvent that can dissolve compound (A), compound (B), and triarylphosphine and is inactive to the radical cation generated from the triarylphosphine.

[0100] Examples of the solvent include dichloromethane, chloroform, acetonitrile, dimethylformamide, cyclohexane, and hexane.

[0101] The solvent may be, for example, a mixed solvent of a polar solvent and a non-polar solvent. Examples of polar solvents include acetonitrile, dimethylformamide, and nitromethane. Examples of non-polar solvents include cyclohexane and hexane.

[0102] When the solvent is a mixed solvent, the volume ratio of the nonpolar solvent to the polar solvent may be, for example, 0.1 or more, 0.2 or more, or 0.3 or more. Also, when the solvent is a mixed solvent, the volume ratio of the nonpolar solvent to the polar solvent may be, for example, 5 or less, 3 or less, 2 or less, or 1 or less.

[0103] In step (I), the reaction mixture may further contain a base.

[0104] As the base, for example, pyridines such as 2,6-lutidine, 2,4-6-trimethylpyridine, pyridine, and N,N-dimethylaminopyridine can be suitably used.

[0105] In step (I), the molar ratio of the base to the compound (A) may be, for example, 0.8 or more, and from the viewpoint of increasing the proportion of the compound (A) involved in the dehydration condensation reaction and proceeding with the reaction more efficiently, it may be 1 or more, 1.1 or more, or 1.2 or more. Furthermore, the molar ratio of the base to the compound (A) may be, for example, 5 or less, 4 or less, 3 or less, or 2 or less.

[0106] In step (I), the reaction liquid may further contain a supporting electrolyte.

[0107] Examples of the supporting electrolyte include sodium perchlorate (NaClO4), tetrabutylammonium perchlorate (Bu4NClO4), tetrabutylammonium tetrafluoroborate (Bu4NBF4), and tetrabutylammonium hexafluorophosphate (Bu4NPF6).

[0108] In step (I), the concentration of the supporting electrolyte in the reaction solution may be, for example, 10 mM or more, or from the viewpoint of more efficiently proceeding with the reaction, 20 mM or more, 30 mM or more, or 40 mM or more. The concentration of the supporting electrolyte in the reaction solution may be, for example, 500 mM or less, 400 mM or less, 300 mM or less, or 200 mM or less.

[0109] In step (I), an electrode (anode) is placed in the reaction solution, and another electrode (cathode) may also be placed in the reaction solution.

[0110] The anode and cathode may be appropriately selected from known electrodes used in electrolytic reactions, and examples of materials for the anode and cathode include platinum, gold, nickel, and carbon.

[0111] The power source for applying a voltage to the anode and cathode is not particularly limited, and may be appropriately selected from known power sources used in electrolytic reactions.

[0112] In step (I), a voltage is applied to the anode in the reaction solution to electrooxidize the triarylphosphine, thereby generating a radical cation.

[0113] The conditions for the electrode oxidation are not particularly limited, and the current density is, for example, 0.1 mA / cm 2 may be greater than or equal to 0.2 mA / cm 2 or more than 0.3mA / cm 2 The current density may be, for example, 2 mA / cm 2 may be less than or equal to 1.5 mA / cm 2 or less than 1mA / cm 2 The current amount may be, for example, 1 F / mol or more, 2 F / mol or more, 3 F / mol or more, or 4 F / mol or more. The current amount may be, for example, 10 F / mol or less, 8 F / mol or less, or 6 F / mol or less.

[0114] The reaction temperature in step (I) is not particularly limited, and may be, for example, 20 to 70°C.

[0115] (Step (II)) The production method of this embodiment may further include step (II) and a deprotection step as steps for obtaining compound (B).

[0116] Step (II) is a step in which compound (a) having a carboxy group derived from an amino acid and an amino group protected with a protecting group is reacted with compound (b) having an amino group derived from an amino acid and a solubilizing tag to obtain compound (c) having a peptide bond, an amino group protected with a protecting group, and a solubilizing tag.

[0117] In step (II), examples of compound (a) include the same compounds as those exemplified as compound (A). Examples of compound (b) include the same compounds as those exemplified as compound (B). Examples of compound (c) include the same compounds as those exemplified as compound (C).

[0118] The reaction in step (II) may be the same as the reaction in step (I). That is, step (II) may be a step of reacting compound (a) with compound (b) in a reaction solution containing the above-mentioned triarylphosphine and in which an electrode for oxidizing the triarylphosphine is placed.

[0119] The reaction solution in step (II) may further contain a base. The reaction solution in step (II) may further contain a supporting electrolyte. Examples of the base and supporting electrolyte in step (II) include the same base and supporting electrolyte as those in step (I).

[0120] (Deprotection step) The deprotection step is a step in which the protecting group on the amino group of compound (c) is deprotected to obtain compound (B).

[0121] The deprotection method may be appropriately selected from known methods depending on the type of protecting group on the amino group.

[0122] In this embodiment, by alternately carrying out step (I) (or step (II)) and the deprotection step, a polypeptide to which any amino acid is linked can be easily produced.

[0123] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. [Example]

[0124] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0125] (Example 1-1) Compounds having peptide bonds were prepared by the following method. A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Pro-OH HO (142.2 mg, 0.40 mmol), HN-Asp (O t Bu)-OTAG (185.7 mg, 0.20 mmol) was dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, and the current was measured at 0.67 mA / cm 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. The target compound (Compound 1-1, Fmoc-Pro-Asp(O t 246.2 mg (98% yield) of (Bu)-OTAG) was obtained. [ka]

[0126] (Example 1-2) Compound 1-1 was produced in the same manner as in Example 1-1, except that di(4-methoxyphenyl)phenylphosphine (193.4 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0127] (Examples 1-3) Compound 1-1 was produced in the same manner as in Example 1-1, except that diphenyl(4-methoxyphenyl)phosphine (175.4 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0128] (Examples 1-4) Compound 1-1 was produced in the same manner as in Example 1-1, except that tris(4-methylphenyl)phosphine (182.6 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0129] (Examples 1-5) Compound 1-1 was produced in the same manner as in Example 1-1, except that diphenyl(4-dimethylaminophenyl)phosphine (183.2 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0130] (Comparative Example 1-1) Compound 1-1 was produced in the same manner as in Example 1-1, except that tris(2-furyl)phosphine (139.3 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0131] (Comparative Example 1-2) Compound 1-1 was produced in the same manner as in Example 1-1, except that tricyclohexylphosphine (168.2 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0132] (Comparative Examples 1-3) Compound 1-1 was produced in the same manner as in Example 1-1, except that tri-n-butylphenylphosphine (121.4 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0133] (Comparative Examples 1-4) Compound 1-1 was produced in the same manner as in Example 1-1, except that tris(4-fluorophenyl)phosphine (189.8 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The results are shown in Table 1.

[0134] [Table 1]

[0135] (Example 2-1) Synthesis of Fmoc-Pro-Pro-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Pro-OH (135.0 mg, 0.40 mmol), and H-Pro-OTAG (170.9 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the reaction mixture was heated at room temperature under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, the solution was cooled to 0°C, and then filtered to obtain 231.5 mg (99% yield) of the target product as a white solid. In this and the following examples, TAG is the same as TAG in compound 1-1. [ka]

[0136] (Comparative Example 2-1) Fmoc-Pro-Pro-OTAG was produced in the same manner as in Example 2-1, except that triphenylphosphine (157.4 mg, 0.60 mmol) was used instead of tris(4-methoxyphenyl)phosphine. The yield was 28%.

[0137] (Example 2-2) Synthesis of Fmoc-Pro-Aib-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Pro-OH (135.0 mg, 0.40 mmol), and HN-Aib-OTAG (168.5 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the reaction mixture was heated at room temperature under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 222.2 mg (95% yield) of the target product was obtained as a white solid. [ka]

[0138] (Example 2-3) Synthesis of Fmoc-Pro-Sar-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Pro-OH (135.0 mg, 0.40 mmol), and HMeN-Gly-OTAG (165.7 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the current was measured at room temperature under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 221.8 mg (97% yield) of the target product was obtained as a white solid. [ka]

[0139] (Example 2-4) Synthesis of Fmoc-Pro-NMePhe-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (246.7 mg, 0.70 mmol), Fmoc-Pro-OH (168.7 mg, 0.50 mmol), and HMeN-Phe-OTAG (183.7 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, which was heated to 60°C and then heated under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C and then filtered. The residue was recovered and subjected to column chromatography (chloroform:2-propanol=80:1) to obtain 62.7 mg (yield 25%) of the target product as a white solid. [ka]

[0140] (Example 2-5) Fmoc-Asp(O t Bu)-Asp(O t Synthesis of (Bu)-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (176.2 mg, 0.50 mmol), Fmoc-Asp (O t Bu)-OH(123.4mg,0.30mmol), H2N-Asp(O tBu)-OTAG (185.7 mg, 0.20 mmol) was dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, and a current of 0.67 mA / cm was applied at room temperature under an argon atmosphere. 2 A constant current of 3.0 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 257.8 mg (98% yield) of the target product was obtained as a white solid. [ka]

[0141] (Example 2-6) Fmoc-Asp(O t Synthesis of Bu)-Pro-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Asp (O t Bu)-OH (164.6 mg, 0.40 mmol) and H-Pro-OTAG (170.9 mg, 0.20 mmol) were dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, and the current was measured at 0.67 mA / cm under an argon atmosphere at room temperature. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 229.9 mg (99% yield) of the target product was obtained as a white solid. [ka]

[0142] (Example 2-7) Fmoc-Asp(O t Synthesis of Bu)-Aib-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Asp (O t Bu)-OH (164.6 mg, 0.40 mmol) and HN-Aib-OTAG (168.5 mg, 0.20 mmol) were dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, which was then heated to 60°C and subjected to a current of 0.67 mA / cm under an argon atmosphere. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 244.0 mg (98% yield) of the target product was obtained as a white solid. [ka]

[0143] (Example 2-8) Fmoc-Asp(O t Synthesis of Bu)-Sar-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (246.7 mg, 0.70 mmol), Fmoc-Asp (O t Bu)-OH (205.7 mg, 0.50 mmol) and HNMe-Gly-OTAG (165.7 mg, 0.20 mmol) were dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, which was then heated to 60°C and subjected to a current of 0.67 mA / cm under an argon atmosphere. 2A constant current of 6.0 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 234.6 mg (96% yield) of the target product was obtained as a white solid. [ka]

[0144] (Example 2-9) Fmoc-Asp(O t Synthesis of Bu)-NMePhe-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (246.7 mg, 0.70 mmol), Fmoc-Asp (O t Bu)-OH (205.7 mg, 0.50 mmol) and HNMe-Phe-OTAG (183.7 mg, 0.20 mmol) were dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, which was then heated to 60°C and subjected to a current of 0.67 mA / cm under an argon atmosphere. 2 A constant current of 6.0 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C and then filtered. The residue was recovered and subjected to column chromatography (chloroform:2-propanol=80:1) to obtain 166.1 mg (yield 63%) of the target product as a white solid. [ka]

[0145] (Example 2-10) Fmoc-Sar-Asp(O t Synthesis of (Bu)-OTAG Acetonitrile (8.0 mL)-cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Sar-OH (124.5 mg, 0.40 mmol), H2N-Asp(O t Bu)-OTAG (185.7 mg, 0.20 mmol) was dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, which was then heated to 60°C and subjected to a current of 0.67 mA / cm under an argon atmosphere. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 223.2 mg (91% yield) of the target product was obtained as a white solid. [ka]

[0146] (Example 2-11) Synthesis of Fmoc-Sar-Pro-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Sar-OH (124.5 mg, 0.40 mmol), and H-Pro-OTAG (170.9 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the current was measured at room temperature under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 216.5 mg (94% yield) of the target product was obtained as a white solid. [ka]

[0147] (Example 2-12) Synthesis of Fmoc-Sar-Aib-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Sar-OH (124.5 mg, 0.40 mmol), and HN-Aib-OTAG (168.5 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, which was heated to 60 °C and maintained at 0.67 mA / cm under an argon atmosphere. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 226.3 mg (99% yield) of the target product was obtained as a white solid. [ka]

[0148] (Example 2-13) Synthesis of Fmoc-Sar-Sar-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Sar-OH (124.5 mg, 0.40 mmol), and HMeN-Gly-OTAG (165.7 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the reaction mixture was heated at room temperature under an argon atmosphere at 0.67 mA / cm. 2A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 219.2 mg (97% yield) of the target product was obtained as a white solid. [ka]

[0149] (Example 2-14) Synthesis of Fmoc-Sar-NMePhe-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (246.7 mg, 0.70 mmol), Fmoc-Sar-OH (155.7 mg, 0.50 mmol), and HMeN-Phe-OTAG (183.7 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, which was heated to 60 °C and maintained at 0.67 mA / cm under an argon atmosphere. 2 A constant current of 6.0 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 232.1 mg (95% yield) of the target product was obtained as a white solid. [ka]

[0150] (Example 2-15) Fmoc-Aib-Asp(O t Synthesis of (Bu)-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Aib-OH (162.7 mg, 0.50 mmol), H2N-Asp(O t Bu)-OTAG (185.7 mg, 0.20 mmol) was dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, and a current of 0.67 mA / cm was applied at room temperature under an argon atmosphere. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 246.5 mg (99% yield) of the target product was obtained as a white solid. [ka]

[0151] (Example 2-16) Synthesis of Fmoc-Aib-Pro-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Aib-OH (162.7 mg, 0.50 mmol), and H-Pro-OTAG (170.9 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the current was measured at room temperature under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. 223.4 mg (96% yield) of the target product was obtained as a white solid. [ka]

[0152] (Example 2-17) Synthesis of Fmoc-Aib-Aib-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (246.7 mg, 0.70 mmol), Fmoc-Aib-OH (162.7 mg, 0.50 mmol), and HN-Aib-OTAG (168.5 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, which was heated to 60 °C and maintained at 0.67 mA / cm under an argon atmosphere. 2 A constant current of 6.0 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C and then filtered. The residue was recovered and subjected to column chromatography (chloroform:2-propanol=80:1) to obtain 184.0 mg (yield 80%) of the target product as a white solid. [ka]

[0153] (Example 2-18) Synthesis of Fmoc-Aib-Sar-OTAG A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), sodium perchlorate (49.0 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (246.7 mg, 0.70 mmol), Fmoc-Aib-OH (162.7 mg, 0.50 mmol), and HMeN-Gly-OTAG (165.7 mg, 0.20 mmol) were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, which was heated to 60 °C and maintained at 0.67 mA / cm under an argon atmosphere. 2A constant current of 6.0 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C and then filtered. The residue was recovered and subjected to column chromatography (chloroform:2-propanol=80:1) to obtain 188.5 mg (83% yield) of the target product as a white solid. [ka]

[0154] (Example 3-1) Synthesis of Rapastinel (i) Condensation reaction A mixture of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) was deoxygenated by bubbling argon gas for 2 minutes, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), Fmoc-Thr(O t Bu)-OH (158.0 mg, 0.40 mmol) and a benzylamino tag of the following formula (T-1-1) (188.6 mg, 0.20 mmol) were dissolved in the reaction solution. A platinum electrode was inserted into the reaction solution, and the voltage was applied at 0.67 mA / cm at room temperature under an argon atmosphere. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C. After filtration, Fmoc-Thr(O t Bu)-NTAG was obtained. [ka]

[0155] (ii) Deprotection reaction The compound obtained by the condensation reaction was dissolved in 6.0 mL of tetrahydrofuran, and piperidine (29.7 μL, 0.30 mmol) and DBU (40 μL, 0.26 mmol) were added, followed by stirring at room temperature for 10 minutes. 6N HCl (60 μL) was added to the solution, followed by approximately 20 mL of acetonitrile, and the solvent was evaporated under reduced pressure. Acetonitrile was added to the residue, and the precipitate was collected by suction filtration to obtain a compound in which the Fmoc group had been deprotected.

[0156] (iii) Synthesis of protected Rapastinel The compound obtained in (ii) above was used as a starting material for the condensation reaction in (i) above, and a peptide bond was formed by condensation with an amino acid protected with an Fmoc group. Then, the Fmoc group was deprotected by the deprotection reaction in (ii) above. In this way, by repeating the reactions in (i) and (ii), Fmoc-Thr(O t Bu)-Pro-Pro-Thr(O t The Rapastinel-protected compound represented by (Bu)-NTAG was obtained (yield 75%, purity 84%). Note that in the condensation reaction using Fmoc-Pro-OH, sodium perchlorate (49.0 mg) was used instead of tetrabutylammonium perchlorate.

[0157] (iv) Synthesis of Rapastinel by deprotection 15.1 mg (0.010 mmol) of the protected product obtained in (iii) above was added to a mixed solution of 1.9 mL of TFA, 0.050 mL of deionized water, and 0.050 mL of triisopropylsilane, heated to 40°C, and stirred for 3 hours. The solution was filtered through a PTFE filter, and the solvent was removed by evaporation under reduced pressure. 20 mL of diisopropyl ether was added to the residue, followed by refrigerated centrifugation. The supernatant was removed, and 20 mL of diisopropyl ether was added to the residue, followed by refrigerated centrifugation. This procedure was repeated once more, followed by lyophilization, yielding 3.4 mg of the desired product, Rapastinel (yield 82%, purity 98%).

[0158] (Example 3-2) Synthesis of Bradykinin (i) Condensation reaction Argon gas was bubbled into a mixed solvent of acetonitrile (8.0 mL) and cyclohexane (4.0 mL) for 2 minutes to deoxygenate the mixture, and then 2,6-lutidine (69.9 μL, 0.60 mmol), tetrabutylammonium perchlorate (136.8 mg, 0.40 mmol), tris(4-methoxyphenyl)phenylphosphine (211.4 mg, 0.60 mmol), an amino acid protected with an Fmoc group (0.40 mmol), and an amino acid (2.0 mmol) having the same TAG as in Example 1-1 were dissolved in the mixture. A platinum electrode was inserted into the reaction solution, and the reaction mixture was heated at room temperature under an argon atmosphere at 0.67 mA / cm. 2 A constant current of 4.8 F / mol was applied. After the reaction, the acetonitrile layer was extracted three times with 15 mL of cyclohexane. The cyclohexane was replaced with acetonitrile, and the solution was cooled to 0°C and filtered to obtain the target product. The amino acids protected with the Fmoc group were Fmoc-Pro-OH or Fmoc-Ser(O t When Bu)-OH was used, sodium perchlorate (49.0 mg) was used instead of tetrabutylammonium perchlorate.

[0159] (ii) Deprotection reaction The compound obtained by the condensation reaction was dissolved in 8.0 mL of tetrahydrofuran, and piperidine (44.5 μL, 0.46 mmol) and DBU (60 μL, 0.40 mmol) were added, followed by stirring at room temperature for 10 minutes. 6N HCl (90 μL) was added to the solution, followed by approximately 20 mL of acetonitrile, and the solvent was evaporated under reduced pressure. Acetonitrile was added to the residue, and the precipitate was collected by suction filtration to obtain a compound in which the Fmoc group had been deprotected.

[0160] (iii) Synthesis of protected Bradykinin By repeating the above steps (i) and (ii), a protected form of Bradykinin (Fmoc-Arg(Pbf)-Pro-Pro-Gly-Phe-Ser(O t 306.7 mg of (Bu)-Pro-Phe-Arg(Pbf)-OTAG) was obtained (yield 62%, purity 83%).

[0161] (iv) Synthesis of Bradykinin by deprotection 24.6 mg (0.010 mmol) of the protected product obtained in (iii) above was added to a mixed solution of 1.9 mL of TFA, 0.050 mL of deionized water, and 0.050 mL of triisopropylsilane, and the mixture was stirred at room temperature for 4 hours. The solution was filtered through a PTFE filter, and the solvent was removed by evaporation under reduced pressure. 20 mL of diisopropyl ether was added to the residue, followed by refrigerated centrifugation. The supernatant was removed, and 20 mL of diisopropyl ether was added to the residue, followed by refrigerated centrifugation. This procedure was repeated once more, followed by lyophilization, yielding 7.4 mg of the desired Bradykinin (yield 70%, purity 81%).

Claims

1. The method includes a step (I) of reacting a compound (A) having a carboxy group derived from an amino acid with a compound (B) having an amino group derived from an amino acid in a reaction solution containing a triarylphosphine having at least one electron-donating group on the aryl group to obtain a compound (C) having a peptide bond, In the step (I), an electrode for oxidizing the triarylphosphine is placed in the reaction solution, and a voltage is applied to the electrode to cause the compound (A) and the compound (B) to react with each other. Methods for producing compounds.

2. The method of claim 1 , wherein the compound (B) has a solubilization tag.

3. The method according to claim 1 , wherein the electron-donating group is an alkoxy group.

4. The method according to claim 1 , wherein the compound (A) and the compound (C) have an amino group protected by a protecting group.

5. a step (II) of reacting a compound (a) having a carboxy group derived from an amino acid and an amino group protected with a protecting group with a compound (b) having an amino group derived from an amino acid and a solubilizing tag to obtain a compound (c) having a peptide bond, an amino group protected with a protecting group, and a solubilizing tag; a deprotection step of deprotecting the compound (c) to obtain the compound (B); Further comprising: The method according to any one of claims 1 to 4.

Images