WO2020137545A1 - アミドの製造方法 - Google Patents
アミドの製造方法 Download PDFInfo
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- WO2020137545A1 WO2020137545A1 PCT/JP2019/048458 JP2019048458W WO2020137545A1 WO 2020137545 A1 WO2020137545 A1 WO 2020137545A1 JP 2019048458 W JP2019048458 W JP 2019048458W WO 2020137545 A1 WO2020137545 A1 WO 2020137545A1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C231/00—Preparation of carboxylic acid amides
- C07C231/02—Preparation of carboxylic acid amides from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
- C07C269/06—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups by reactions not involving the formation of carbamate groups
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07K—PEPTIDES
- C07K1/00—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length
- C07K1/02—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length in solution
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07K—PEPTIDES
- C07K1/00—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length
- C07K1/02—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length in solution
- C07K1/023—General methods for the preparation of peptides, i.e. processes for the organic chemical preparation of peptides or proteins of any length in solution using racemisation inhibiting agents
Definitions
- the present invention relates to a method for producing an amide.
- This application claims the priority right based on Japanese Patent Application No. 2018-241598 filed in Japan on December 25, 2018, the content of which is incorporated herein.
- the carboxyl group of an amino acid is activated and reacted with the amino group of an amino acid to cause a coupling reaction to form an amide bond, which is repeated to sequentially extend the amino acid. ..
- Several methods are known as methods for activating a carboxyl group. There are a method of synthesizing a peptide while suppressing isomerization and formation of a by-product using a condensing agent having a weak activation degree, and a method of synthesizing a peptide in a short time using an activating agent.
- a method of activating the carboxyl group using a highly active activator there are an acid chloride method and an acid anhydride method.
- the acid chloride method and the acid anhydride method have a simpler structure of the activator as compared with the activation method using a condensing agent having a weak activation degree, so that the unit price is low, and further the activator is There are advantages such as less generation of by-products.
- the acid anhydride method is divided into a symmetrical acid anhydride method and a mixed acid anhydride method.
- Non-Patent Documents 1 and 2 disclose a method for synthesizing an amide using a symmetrical acid anhydride as an active species of a carboxylic acid.
- the symmetrical acid anhydride method disclosed in Non-Patent Documents 1 and 2 is A first step of producing a symmetrical acid anhydride by a condensation reaction between carboxylic acids; A second step of performing a coupling reaction between the symmetrical acid anhydride and an amine, It can be said that the method includes.
- Non-Patent Document 3 discloses a method for synthesizing an amide using a mixed acid anhydride as an active species of a carboxylic acid.
- carboxylic acid and isopropyl chloroformate are mixed in a first micromixer to synthesize a mixed acid anhydride in a short time, and immediately thereafter, the synthesized mixed acid anhydride is not racemized immediately. It is described that a solution containing a mixed acid anhydride, an amine and a catalyst (base) are mixed in a second micromixer to perform amidation.
- the mixed acid anhydride method disclosed in Non-Patent Document 3 is A first step of reacting a carboxylic acid with a chloroformate to obtain a mixed acid anhydride; A second step of adding a base to the mixed acid anhydride to obtain an acylpyridinium species; A third step of performing a coupling reaction between the acylpyridinium species and an amine to obtain an amide; It can be said that the method includes.
- the symmetric acid anhydride method has a problem that the symmetric acid anhydride has a low reactivity with an amine, and thus the coupling reaction with an amine having a low nucleophilicity takes time or does not proceed.
- the coupling reaction can proceed even with an amine having a low nucleophilicity.
- an undesired side reaction product an epimer
- a usual coupling reaction represented by a natural amino acid there is a sufficient difference between the reaction rate of racemization of an amino acid and the reaction rate of formation of an objective substance, and epimer formation hardly occurs.
- the difference between the reaction rate of racemization and the reaction rate of the desired product is not sufficient, and epimer formation may not be suppressed in some cases.
- the present invention has been made in order to solve the above-mentioned problems, in which a carboxyl group is activated and reacted with an amino group to cause a coupling reaction to form an amide bond. It is an object of the present invention to provide a method for producing an amide, which has good efficiency and is less likely to cause side reactions such as epimer formation.
- one aspect of the present invention is as follows.
- the acid is at least one selected from the group consisting of hydrogen halide, perchloric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, fluorosulfonic acid and paratoluenesulfonic acid, (1) A method for producing an amide according to any one of to (7).
- the first base is at least one selected from the group consisting of pyridine, pyridine derivatives, imidazole, imidazole derivatives, and 1,4-diazabicyclo[2,2,2]octane.
- the first base is 4-morpholinopyridine, N,N-dimethyl-4-aminopyridine, 4-pyrrolidinopyridine, pyridine, 4-methoxypyridine, imidazole, N-methylimidazole and 1,4- The method for producing an amide according to any one of (1) to (11) above, which is one or more selected from the group consisting of diazabicyclo[2,2,2]octane.
- the method for producing the amide of the embodiment is the following method 1) or 2). 1) after dehydration condensation of carboxylic acids with each other, the reaction with a first base and the reaction with an amine to obtain an amide, the reaction with the first base and/or the reaction with an amine A method for producing an amide, wherein 2) reacting a carboxylic acid with a halogenated formic acid ester, and then reacting with a first base to react with an amine to obtain an amide, and reacting with the first base and/or with an amine A method for producing an amide, wherein the reaction is performed by adding an acid.
- the method for producing an amide of the embodiment according to the above 1) a product obtained by reacting a mixture obtained by mixing a first carboxylic acid and a second carboxylic acid, a first base, and an acid.
- the method for producing an amide may include mixing an amine with an amine.
- the method for producing an amide of the embodiment according to 1) above is a mixture obtained by mixing a first carboxylic acid, a second carboxylic acid and phosgene or a phosgene equivalent that decomposes in the reaction system to produce phosgene. It may be a method including mixing a product obtained by reacting with a first base, an acid, and an amine.
- the product obtained by reacting the mixture obtained by mixing the first carboxylic acid and the second carboxylic acid is an acid anhydride obtained by dehydration condensation of the first carboxylic acid and the second carboxylic acid.
- a product obtained by reacting a mixture obtained by mixing a carboxylic acid and a halogenated formic acid ester, a first base, an acid, and an amine are used. It may be a method for producing an amide, which comprises mixing.
- the method for producing an amide of the embodiment according to the above 2) includes a product obtained by reacting a mixture obtained by mixing a carboxylic acid, a second base that activates a halogenated formate, and a halogenated formate.
- the method for producing an amide may include mixing a first base, an acid, and an amine.
- a product obtained by reacting a mixture obtained by mixing a carboxylic acid and a halogenated formate or a carboxylic acid, a second base that activates the halogenated formate and a halogenated formate are mixed.
- the product obtained by reacting the resulting mixture may contain a mixed acid anhydride.
- the said 1st base may produce a cationic active species, and may be a base (however, this amine is excluded).
- mixing refers to the operation of adding substances such as raw materials to the reaction system.When these substances are mixed in the reaction system, the raw materials and the like change to substances different from those before addition. May be
- the case where the acid anhydride is obtained by the method 1) and the case where the acid anhydride is obtained by the method 2) can be exemplified.
- Both of the methods 1) and 2) for the preparation of amides are common with respect to obtaining the "anhydride" from a carboxylic acid and then reacting it with a first base, ie 1) or 2
- the method for producing an amide)) may include the following steps 1 to 3.
- the reaction of the method for producing an amide according to the present invention is not limited to the reactions exemplified in the following steps.
- Step 1 A step of obtaining an acid anhydride from a carboxylic acid.
- Step 2 a step of reacting the acid anhydride obtained in Step 1 with a first base to obtain a cationic active species.
- Step 3 A step of reacting the cationic active species obtained in Step 2 with an amine to produce an amide.
- the amide production methods 1) and 2) above are carried out by adding an acid in the following reaction.
- the reaction of the step 2 is performed by adding an acid
- the reaction of the step 3 is performed by adding an acid
- the reaction of the steps 2 and 3 is performed by adding an acid.
- the acid may be added in advance in the step of step 1, but from the viewpoint of reaction efficiency, it is preferable to add the acid after step 1, and it is more preferable to add the acid together with the first base. preferable.
- the acid is added after step 1, it is considered that the reaction of step 2 or the reaction of step 2 and step 3 becomes a reaction in the presence of acid.
- the presence of an acid means, for example, in a solvent to which an acid is added.
- an amide is manufactured by adding an acid together with the first base after Step 1.
- the following amide production method 1') or 2') is preferable.
- a method for producing an amide which comprises reacting with an acid by adding an acid. 2′) reacting a carboxylic acid with a halogenated formic acid ester, then adding an acid to react with a first base and reacting with an amine to obtain an amide, and reacting with the first base
- a method for producing an amide wherein the reaction with an amine is performed by adding an acid.
- the case where an acid is added together with the first base will be mainly described. When the acid is added with the first base, a mixture of the first base and the acid may be added.
- step 1 carboxylic acids are dehydrated and condensed by the method in 1') to obtain an acid anhydride.
- step 1, step 2 and step 3 correspond to step 1-1, step 2-1 and step 3-1 respectively.
- step 1, step 2 and step 3 correspond to step 1-2, step 2-2 and step 3-2, respectively.
- both the step 1-1 and the step 1-2 may be simply referred to as the step 1, and both the step 2-1 and the step 2-2 may be simply referred to as the step 2.
- Yes and may refer to both step 3-1 and step 3-2, and may be simply abbreviated as step 3.
- the production method of 1' may include the following steps 1-1 to 3-1.
- Step 1-1 A step of dehydrating and condensing carboxylic acids to obtain an acid anhydride.
- Step 2-1 A step of adding an acid and reacting the acid anhydride obtained in Step 1-1 with a first base to obtain a cationic active species.
- Step 3-1 A step of reacting the cationic active species obtained in Step 2-1 with an amine to produce an amide.
- Step 1-1 is a step of dehydrating and condensing carboxylic acids to obtain an acid anhydride.
- the carboxylic acids can be dehydrated and condensed with each other by reacting phosgene or a phosgene equivalent that decomposes in the reaction system to produce phosgene.
- the carboxylic acid may be any one as long as it has a carboxyl group at the end of the molecule and can be represented by the following general formula (1).
- R 1 is a hydrogen atom or a monovalent organic group.
- Carboxylic acid may be deprotonated to a carboxylate ion, which can be represented by the following general formula (1i).
- R 1 is a hydrogen atom or a monovalent organic group.
- Deprotonation of a carboxylic acid can be achieved by placing the carboxylic acid in the presence of a base having a low nucleophilicity such as N,N-diisopropylethylamine (DIEA) in the reaction system.
- a base having a low nucleophilicity such as N,N-diisopropylethylamine (DIEA)
- DIEA N,N-diisopropylethylamine
- the presence of a base means, for example, in a solvent to which a base is added.
- the type of the base is not particularly limited as long as it can deprotonate the carboxylic acid in the reaction system.
- the carboxylic acid represented by the following general formula (1) and the carboxylic acid represented by the following general formula (1)′ are dehydrated and condensed to give
- the acid anhydride represented by the formula (2) is obtained.
- the acid anhydride can be obtained, for example, by reacting carboxylic acid with phosgene or a phosgene equivalent that decomposes in the reaction system to produce phosgene.
- R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group.
- a phosgene equivalent is one that decomposes in the reaction system to produce phosgene, and can be used as a substance substantially equivalent to phosgene in the synthetic reaction.
- Examples of the phosgene equivalent include diphosgene and triphosgene.
- carboxylic acids of different types may be dehydrated and condensed, or carboxylic acids of the same type may be dehydrated and condensed. That is, R 1 and R 2 in the formulas (1) and (1)′ may be the same or different from each other.
- the acid anhydride represented by the general formula (2) is a symmetrical acid anhydride.
- the counter anion of the cationic active species produced in step 2-1 described later is the same as the carboxylate ion before activation.
- the counter anion may self-react with the cationic active species, but if the counter anion is the same as the carboxylate ion before activation, the product will be activated by the cationic active species even if it self-reacts.
- the carboxylic acid is preferably an amino acid or an amino acid derivative.
- the carboxylic acid here includes a carboxylic acid that is a precursor of an acid anhydride.
- the amino acid is preferably an ⁇ -amino acid.
- the amino acids constituting the peptide or protein in vivo are usually L-type, the amino acids may be L-type.
- the ⁇ -amino acid may be a compound represented by the following general formula (1-1).
- R 0 represents a side chain of an amino acid.
- the amino acids may be 20 kinds of amino acids that constitute peptides or proteins in vivo and are encoded as genetic information.
- these amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine.
- the amino acid may be a type of amino acid that is not encoded as genetic information such as cystine.
- R 0 in the above formula (1-1) is “—CH 3 ”when the amino acid is alanine, “—H” when glycine, and “ ⁇ H” when valine. CH(CH 3 ) 2 ”, and in the case of isoleucine, it is “—CH(CH 3 )CH 2 CH 3 ”.
- —R 1 and —R 2 may be —CH(R 0 )NH 2 , respectively.
- the above amino acids do not have to be ⁇ -amino acids.
- it may be a ⁇ -amino acid such as ⁇ -alanine.
- the carboxylic acid may be an amino acid derivative.
- the amino acid derivative may be a compound having substantially the same properties as an amino acid, may be a naturally occurring natural type, and may be a modification different from the natural type, addition, modification such as substitution of a functional group. Etc. may be included.
- An example of a case having properties substantially equivalent to an amino acid is a case where it can be incorporated into an enzyme having an amino acid as a substrate or can bind to a molecule that binds to an amino acid.
- Examples of the amino acid derivative include amino acids in which one or more hydrogen atoms or groups are substituted with other groups (substituents).
- a protected amino acid in which a functional group is protected with a protecting group can be mentioned.
- the protecting group has a function of inactivating the reactive functional group. It is also possible to deprotect the protecting group and return the protected functional group to its pre-protected state.
- that the functional group is protected means that the atom constituting the functional group is substituted with a protecting group.
- the site protected by the protecting group includes at least one site selected from the group consisting of an amino group, a carboxyl group, and a side chain.
- the functional group contained in the side chain may be protected at one site or at two or more sites with a protective group.
- the amino group and/or the functional group of the side chain is preferably protected so as to prevent the reaction of the reactive functional group other than the carboxyl group.
- the type of protective group is not particularly limited and can be appropriately selected depending on the type of functional group to be protected.
- examples of the amino-protecting group include, but are not limited to, carbamate-based, sulfonamide-based, acyl-based and alkyl-based protecting groups.
- carbamate-based protecting group a 2-benzyloxycarbonyl group (sometimes abbreviated as —Z or —Cbz), a tert-butoxycarbonyl group (sometimes abbreviated as —Boc), and allyloxy.
- Carbonyl group (sometimes abbreviated as -Alloc), 2,2,2-trichloroethoxycarbonyl group (sometimes abbreviated as -Troc), 2-(trimethylsilyl)ethoxycarbonyl group (-Teoc) Abbreviated), 9-fluorenylmethyloxycarbonyl group (sometimes abbreviated as -Fmoc), p-nitrobenzyloxycarbonyl group (-Z(NO 2 )) ), a p-biphenylisopropyloxycarbonyl group (sometimes abbreviated as -Bpoc), and the like.
- sulfonamide-based protecting group examples include a p-toluenesulfonyl group (sometimes abbreviated as —Ts or —Tos) and a 2-nitrobenzenesulfonyl group (sometimes abbreviated as —Ns), 2 , 2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl (sometimes abbreviated as -Pbf), 2,2,5,7,8-pentamethylchroman-6-sulfonyl (-Pmc Abbreviated as ".”, 1,2-dimethylindole-3-sulfonyl (sometimes abbreviated as "-MIS”) and the like.
- a p-toluenesulfonyl group sometimes abbreviated as —Ts or —Tos
- 2-nitrobenzenesulfonyl group sometimes abbreviated as —Ns
- 2 2,4,6,7-pentamethyldihydro
- the amide production method of the embodiment epimer formation of the amide can be suppressed. Therefore, the amide production method of the embodiment is suitable for reaction with a raw material carboxylic acid that easily causes epimer formation of the amide.
- carboxylic acid that easily causes epimer formation of amide include phenylglycine, cysteine, serine, aspartic acid, histidine, and derivatives thereof.
- Step 2-1 is a step of adding an acid and reacting the acid anhydride obtained in Step 1-1 with the first base to obtain a cationic active species.
- step 2-1 of the method for producing an amide according to the embodiment an acid anhydride represented by the following general formula (2), a first base represented by B, and an acid represented by A are added. And react to obtain a cationic active species represented by the following general formula (4).
- a compound represented by the following general formula (5) is produced as a counter anion of the cationic active species.
- R 1 and R 2 are each independently a hydrogen atom or a monovalent organic group.
- the acid added in step 2-1 may be either an inorganic acid or an organic acid, and examples thereof include hydrochloric acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypoperchloric acid, hydrobromic acid, Hypobromic acid, bromic acid, hydrofluoric acid, nitric acid, sulfuric acid, persulfuric acid, phosphoric acid, perphosphoric acid, hexafluorophosphoric acid, potassium dihydrogen phosphate, sodium dihydrogen phosphate, hexafluoroantimonic acid, iodine Acid, hypoiodic acid, periodic acid, boric acid, tetrafluoroboric acid, carbonic acid, percarbonic acid, permanganic acid, chromic acid, thiocyanic acid, acetic acid, peracetic acid, trifluoroacetic acid, chloroacetic acid, dichloroacetic acid, trichloro Acetic acid, benzoic acid, perbenzoic acid, metachlor
- the acid added here may be a carboxylic acid.
- the carboxylic acid is used in advance, but the carboxylic acid in step 1-1 is converted to an active species as an acid anhydride. Even if the carboxylic acid is added in step 2-1, the added carboxylic acid is unlikely to be an active species, and the carboxylic acid added in step 2-1 is difficult to be incorporated as a constituent unit of the amide.
- the acid may be a carboxylic acid. However, the acid is preferably an acid excluding carboxylic acid.
- the acid is preferably one or more selected from the group consisting of hydrogen halide, perchloric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, fluorosulfonic acid and paratoluenesulfonic acid.
- Hydrogen halide is more preferable, and hydrochloric acid is more preferable.
- Addition of an acid can suppress the formation of an amide epimer, improve the coupling reaction rate between a carboxylic acid and an amine, and allow the amide to be produced with extremely high efficiency.
- the first base in step 2-1 is one that reacts with the acid anhydride to generate a cationic active species, and is preferably highly nucleophilic, such as pyridine, pyridine derivative, imidazole, imidazole derivative and More preferably, it is at least one selected from the group consisting of 1,4-diazabicyclo[2,2,2]octane.
- the pyridine derivative may be one in which one or more hydrogen atoms of pyridine are substituted with another group, and is not particularly limited as long as it has a basic property.
- the compound represented by formula (3-1) is preferable.
- X 1 represents a hydrogen atom or any group selected from the group represented by the following formulas (a) to (c).
- R 31 , R 32 , R 33, and R 34 each independently represent an alkyl group.
- R 33 and R 34 may be bonded to each other to form a ring.
- One methylene group not directly bonded to R 33 or R 34 may be substituted with an oxygen atom.
- the alkyl group in R 31 , R 32 , R 33 and R 34 may be linear, branched or cyclic. When it is cyclic, the alkyl group may be either monocyclic or polycyclic. The alkyl group may have 1 to 20 carbon atoms, 1 to 15 carbon atoms, or 1 to 10 carbon atoms.
- linear or branched alkyl group examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group.
- the compound represented by the general formula (3-1) is preferably a compound represented by the following general formula (3-1-1).
- X 1 is any group selected from the group represented by the above formulas (a) to (c) other than a hydrogen atom, X 1 acts as an electron-donating group by bonding to such a position. Tend to be more effective and the nucleophilicity of the N atom of the pyridine ring tends to be better.
- X 1 is a group represented by the above formula (c)
- R 33 and R 34 are bonded to each other to form a ring
- the alkyl group is
- 4-morpholinopyridine represented by the following formula (3-1-2) is included.
- Preferred examples of the pyridine and pyridine derivatives include pyridine, the above-mentioned 4-morpholinopyridine, N,N-dimethyl-4-aminopyridine, 4-pyrrolidinopyridine and 4-methoxypyridine.
- 4-morpholinopyridine and N,N-dimethyl-4-aminopyridine by using them, have a high amide synthesis yield per unit time and significantly reduce the production of by-products. It is particularly preferable in that it can be performed.
- the cationic active species in the case of using the pyridine and the pyridine derivative exemplified above is an acylpyridinium cation (acylpyridinium species).
- Acylpyridinium species are characterized by high electrophilicity. Therefore, even in the case of a reaction with an amine having a low nucleophilicity, which will be described later, it is possible to proceed the reaction at a very high rate and to significantly reduce the production of by-products.
- the imidazole derivative may be one or more hydrogen atoms of imidazole, which may be substituted with other groups, and is not particularly limited as long as it has the property of a base, but the imidazole and the imidazole derivative are as follows.
- the compound represented by formula (3-2) is preferable.
- R 35 and R 36 are each independently a hydrogen atom or an alkyl group.
- Examples of the alkyl group for R 35 and R 36 include those exemplified for the alkyl group for R 31 , R 32 , R 33, and R 34 .
- imidazole and imidazole derivative imidazole and N-methylimidazole can be exemplified as preferable ones.
- pyridine derivatives in addition to pyridine, pyridine derivatives, imidazole, and imidazole derivatives, 1,4-diazabicyclo[2,2,2]octane (DABCO) can be mentioned as a preferable example.
- DABCO 1,4-diazabicyclo[2,2,2]octane
- Step 3-1 is a step of reacting the cationic active species obtained in Step 2-1 with an amine to produce an amide.
- a cationic active species represented by the following general formula (4) is reacted with an amine represented by the following general formula (6) to carry out the following general synthesis.
- the amide represented by the formula (7) is obtained.
- the acid added in Step 2-1 may be present in the reaction system.
- R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom or a monovalent organic group.
- the amine is preferably an amino acid or an amino acid derivative.
- the amino acids and amino acid derivatives include those exemplified for the carboxylic acid.
- -R 3 and -R 4 may be, for example, -H and -CH(R 0 )COOH.
- a protected amino acid in which a functional group is protected with a protecting group can be mentioned.
- the site protected by the protecting group includes at least one site selected from the group consisting of an amino group, a carboxyl group, and a side chain.
- the functional group contained in the side chain may be protected at one site or at two or more sites with a protective group.
- the type of protecting group is not particularly limited and can be appropriately selected according to the type of functional group to be protected.
- the protection of the carboxyl group may be carried out by neutralizing it to the salt form, but usually it is protected in the ester form.
- the ester include alkyl esters such as methyl and ethyl, and benzyl ester (sometimes abbreviated as Bn or BZl), but are not limited thereto.
- step 3-1 the cationic active species is reacted with an amine.
- the method for producing an amide of the embodiment has an advantage that the reaction rate does not depend on the nucleophilicity of the amine because the electrophilicity of the cationic active species is high. Therefore, the method for producing the amide of the embodiment is suitable for the reaction with an amine having low nucleophilicity.
- the amine having a low nucleophilicity is, specifically, an amine having a nucleophilicity lower than that of 18 amino acids excluding valine and isoleucine from the 20 amino acids constituting a protein and encoded as genetic information.
- valine, isoleucine or N-alkylated amino acid, or a derivative thereof can be exemplified.
- the N-alkylated amino acid may be one in which one or two hydrogen atoms of an amino group bonded to ⁇ carbon are substituted with an alkyl group, and one or two hydrogen atoms are substituted with a methyl group. N-methyl amino acids are preferred.
- These amines having low nucleophilicity have hitherto been difficult to use for synthesis by the acid anhydride method.
- an amine having a low nucleophilicity which has hitherto been difficult to use in the synthesis by the acid anhydride method, can be used.
- the method for producing the amide in the form is epoch-making.
- the nucleophilicity of the amine here is determined by, for example, performing an acid anhydride method under the conditions shown in Example 1 and reacting the acid anhydride produced in Example 1 with an amine whose nucleophilicity is desired to be obtained. , It can be determined from the degree of its reaction efficiency.
- the manufacturing method of 2' may include the following steps 1-2 and 3-2.
- Step 1-2 A step of reacting a carboxylic acid with a halogenated formic acid ester to obtain a mixed acid anhydride.
- Step 2-2 A step of adding an acid and reacting the mixed acid anhydride obtained in Step 1-2 with the first base to obtain a cationic active species.
- Step 3-2 A step of reacting the cationic active species obtained in Step 2-2 with an amine to produce an amide.
- the reaction of the method for producing an amide according to the present invention is not limited to the reactions exemplified in the following steps.
- Step 1-2 is a step of reacting a carboxylic acid and a halogenated formate to obtain a mixed acid anhydride.
- step 1-2 of the method for producing an amide according to the embodiment a carboxylic acid represented by the following general formula (I) is reacted with a halogenated formic acid ester represented by the following general formula (I)′, A mixed acid anhydride represented by the following general formula (II) is obtained.
- R 11 represents a hydrogen atom or a monovalent organic group
- R 12 represents a hydrogen atom or a hydrocarbon group
- Y represents a halogen atom.
- Examples of the carboxylic acid include those exemplified in the above ⁇ First Embodiment>.
- Halogenation in a halogenated formate ester means that a halogen atom is bonded to a carbonyl group.
- the hydrocarbon group for R 12 may be either an aliphatic hydrocarbon group or an aromatic hydrocarbon group (aryl group).
- the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group (alkyl group) or an unsaturated aliphatic hydrocarbon group, preferably an alkyl group.
- the aliphatic hydrocarbon group may have 1 to 20 carbon atoms or 1 to 15 carbon atoms.
- the alkyl group may be linear, branched or cyclic. When it is cyclic, the alkyl group may be either monocyclic or polycyclic.
- the alkyl group may have 1 to 20 carbon atoms, 1 to 10 carbon atoms, or 1 to 5 carbon atoms.
- linear or branched alkyl group examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group.
- the halogen atom of Y is an element belonging to Group 17 in the periodic table such as F, Cl, Br and I, and Cl or Br is preferable.
- the halogen atom of Y is Cl or Br
- the hydrocarbon group of R 12 is It is preferably a branched chain alkyl group having 1 to 5 carbon atoms, and is selected from the group consisting of isopropyl chloroformate, isobutyl chloroformate, ethyl chloroformate, isopropyl bromoformate, isobutyl bromoformate and ethyl bromoformate. More preferably, it is one or more.
- the second base that activates the halogenated formate ester may be reacted with the halogenated formate ester to facilitate the reaction.
- the activated halogenated formate ester is also included in the concept of halogenated formate ester.
- the second base reacts with the halogenated formate to generate a cationic active species, and is preferentially used with the halogenated formate over the mixed acid anhydride as the product of Step 1-2.
- the pyridine derivative and the imidazole derivative include those exemplified in the above step 2-1.
- at least one of the groups attached to the N atom of the amine is preferably a methyl group. It is more preferable that two of the groups bonded to the N atom of the amine are methyl groups.
- the second base are 4-methylmorpholine, N-methylimidazole, N,N-dimethylbenzylamine, N,N-dimethylbutylamine, N,N-dimethylallylamine, 1,4 Examples include, but are not limited to: diazabicyclo[2,2,2]octane, N,N-dimethyl-4-aminopyridine (DMAP), N-methylpiperidine.
- N,N-dimethylbenzylamine is preferable to use. Addition of an excess of the second base to the reaction system may cause precipitation (salt formation) due to addition of the acid.
- N,N-dimethylbenzylamine has a good reactivity, and the reaction is likely to proceed even if the equivalent weight is lowered, so that the problem of precipitation hardly occurs. Therefore, N,N-dimethylbenzylamine is suitable for a production method using a flow reactor that is easily affected by precipitation.
- Step 2-2 is a step of adding an acid and reacting the mixed acid anhydride obtained in Step 1-2 with the first base to obtain a cationic active species.
- a mixed acid anhydride represented by the following general formula (II) a first base represented by B, and an acid represented by A are A cationic active species represented by the following general formula (IV) is obtained by adding and reacting.
- a compound represented by the following general formula (V) is produced as a counter anion of the cationic active species.
- Examples of the acid include those exemplified in the above ⁇ First Embodiment>.
- Examples of the first base include those exemplified in the above ⁇ First Embodiment>.
- ⁇ Addition of acid can suppress the formation of epimer of amide and improve the coupling reaction rate of carboxylic acid and amine, which makes it possible to produce amide with extremely high efficiency.
- Step 3-2 is a step of reacting the cationic active species obtained in step 2-2 with an amine to produce an amide.
- a cationic active species represented by the following general formula (IV) is reacted with an amine represented by the following general formula (VI) to carry out the following general synthesis. It is intended to obtain an amide represented by the formula (VII).
- the acid added in the above step 2-2 may be present in the reaction system.
- Formula (VI) and formula (VII) representing the same meaning as R 11 in formula (II), respectively Each independently represent a hydrogen atom or a monovalent organic group.
- R 12 in formula (V) has the same meaning as R 12 in formula (II).
- amine examples include those exemplified in the above ⁇ First Embodiment>.
- alkoxide (O ⁇ —R 12 ) and CO 2 may be generated instead of the formula (V).
- the amount of each compound used in the reaction of steps 1 to 3 may be appropriately adjusted according to the intended reaction in consideration of the types of these compounds.
- the molar equivalent ratio (activated carboxylic acid:amine) of the activated carboxylic acid and the amine in the reaction system may be 10:1 to 1/10:1 and 5:1 to 1/5: It may be 1 and may be 3:1 to 1/3:1.
- the activated carboxylic acid is, for example, a compound represented by the general formula (4) or (IV). According to the method for producing an amide of the embodiment, it is possible to produce an amide with high efficiency even when a relatively small amount of amine, which is close to an equivalent amount, is reacted with an activated carboxylic acid.
- the molar equivalent ratio (activated carboxylic acid:acid) of the activated carboxylic acid and the acid in the reaction system is 10:0.1 to 10:5 from the viewpoint of reaction efficiency. It may be 10:0.5 to 10:4.
- the reaction time of each step may be appropriately adjusted according to the reaction temperature and other conditions.
- the reaction time in Step 1 may be 0.05 seconds to 30 minutes, 0.1 seconds to 5 minutes, or 0.5 seconds to 30 seconds.
- the reaction time of Step 2 and Step 3 may be 1 second to 60 minutes, 5 seconds to 30 minutes, or 1 minute to 10 minutes. Good.
- reaction temperature may be appropriately adjusted according to the kind of the compound used in steps 1 to 3.
- reaction temperature is preferably in the range of 0 to 100°C, more preferably 20 to 60°C.
- the reactions of steps 1 to 3 may be carried out in the coexistence of a solvent.
- the solvent is not particularly limited, but those that do not interfere with the reaction of the compound are preferable, and those that have high solubility of the raw materials used in the reaction are preferable. Examples thereof include N,N-dimethylformamide (DMF), tetrahydrofuran (THF), 1,4-dioxane, acetonitrile, dimethoxyethane and the like.
- reaction of Step 1 to Step 3 may further include other compounds that do not correspond to the above-exemplified compounds in the reaction system, as long as the formation of amide can be achieved.
- the reactions of steps 1 to 3 may be performed separately or simultaneously. From the viewpoint of more effectively suppressing the production of the side reaction product, it is preferable to perform step 2 and step 3 at the same time.
- the existence and structure of the product can be confirmed by measurement of a spectrum obtained by analysis of NMR, IR, mass, etc., elemental analysis, or the like. If necessary, the product may be purified, and as a purification method, it can be purified by distillation, extraction, recrystallization, column chromatography or the like.
- the amide can be produced with extremely high efficiency. Even the acid anhydride obtained in step 1 is in a state of accepting a nucleophilic species (amine) as an active species.
- a cationic active species is further formed, and an amine is reacted therewith for the first time.
- the cationic active species generated here have a remarkably high activity as compared with the acid anhydride, so that the reaction can proceed at an extremely fast rate, and the formation of by-products is also increased as compared with the conventional method. It can be suppressed dramatically. Furthermore, it is possible to easily proceed the reaction even with an amine having a low reactivity, which was difficult to react by the conventional method.
- the addition of an acid to the reaction system can possibly enhance the production of an intermediate (for example, a cationic active species) derived from a carboxylic acid, and at the same time, the amide epimer. Generation can be suppressed.
- an intermediate for example, a cationic active species
- Generation can be suppressed.
- the mechanism by which these effects occur can be considered as follows, for example. First, it is considered that addition of an acid supplies a proton to the reaction system and suppresses racemization in the intermediate derived from the carboxylic acid as a raw material. Racemization can occur when the proton-depleted anion is a stable structure and is reprotonated.
- racemization is more likely to occur under basic conditions, and it is considered that racemization is suppressed by adding an acid to approach neutral conditions.
- addition of an acid neutralizes excess base and suppresses racemization in an intermediate derived from a carboxylic acid as a raw material.
- Racemization in this case is an intermediate produced by reacting an intermediate derived from a raw material carboxylic acid (for example, a cationic active species) with a base, and when the anion desorbed from the proton has a stable structure, It is considered that the racemization is suppressed by inhibiting the reaction with the base by adding the acid. This is understood to be the case when side reactions are suppressed in step 2 and/or step 3.
- a peptide or a protein can be synthesized.
- the method for producing a peptide or protein is included in the method for producing an amide.
- the polypeptide chain can be extended by using the amide obtained in step 3 above as the carboxylic acid in step 1 and repeating steps 1 to 3 after steps 1 to 3.
- the carboxylic acid also includes a polypeptide
- the amino acid or amino acid derivative (carboxylic acid) according to the embodiment also includes an amino acid or amino acid derivative (carboxylic acid) located at the C-terminal as a constituent unit of the polypeptide.
- the amide production method of the embodiment is suitable as a peptide or protein production method.
- the method for producing an amide of the embodiment can be carried out using a flow reactor.
- the flow reactor include a flow path for transporting a fluid containing a raw material or an intermediate used in the reaction in the amide production method of the embodiment, and a mixer for mixing the fluid.
- the reaction with the amine in at least the step 3 may be carried out in the flow reactor, and the reaction with the first base in the step 2 and the step 3 may be performed to obtain the amine.
- the reaction for reacting with may be carried out in a flow reactor, and the reaction for reacting with the first base after obtaining the acid anhydride and reacting with the amine in the steps 1 to 3 may be carried out.
- the method for producing the amide of the embodiment is not limited to the method performed using a flow reactor.
- a batch container having a small volume and capable of obtaining a high stirring speed may be used.
- the volume of the mixing part of the batch container may be 1 to 100 mL, or 5 to 50 mL.
- FIG. 1 is a schematic diagram showing a schematic configuration of a flow reactor 1.
- the flow reactor 1 includes a tank 11 that stores a first liquid, a tank 12 that stores a second liquid, and a tank 13 that stores a third liquid.
- the first liquid can include a carboxylic acid
- the second liquid can include a halogenated formate ester
- the third liquid can include a first base, an acid, and an amine.
- the first liquid contains a carboxylic acid and a second base that activates the halogenated formate ester
- the second liquid contains a halogenated formate ester
- the third liquid contains the first base
- Acids and amines can be included.
- the first liquid contains carboxylic acid, N,N-dimethylbenzylamine (second base) and DIEA
- the second liquid is isopropyl chloroformate
- the third liquid contains N-methylimidazole (first base), hydrochloric acid (acid) and amine.
- the mixture of at least the first liquid and the second liquid and the third liquid may be mixed in the flow-through reaction device.
- the mixing of the liquid of (1) and the second liquid may be performed in a flow reactor.
- the flow reactor 1 has flow paths f1, f2, f3, f4, f5 for transporting a fluid.
- the inner diameter of the channel may be, for example, 0.1 to 10 mm, or 0.3 to 8 mm.
- the flow reactor 1 includes mixers 31 and 32 for mixing fluids.
- the inner diameter of the flow path inside the mixer may be, for example, 0.1 to 10 mm, or may be 0.3 to 8 mm.
- Examples of the mixer include a static mixer having no driving unit.
- the drive unit refers to a portion that is powered and moves.
- the inner diameter of the flow path may be a diameter of a portion inside the flow path (a portion through which the fluid passes) in the flow path cross section in a direction orthogonal to the length direction of the flow path.
- the inside diameter of the above-mentioned flow path can be the diameter when the shape of the inside of the flow path is converted into a perfect circle on the basis of area.
- the tanks 11, 12, 13, and 14, the mixers 31 and 32, and the flow paths f1, f2, f3, f4, and f5 are made of, for example, a resin such as plastic or elastomer, a glass material, a metal, a ceramic, or the like. There is.
- the tank 11 is connected to the pump 21, and by the operation of the pump 21, the first liquid contained in the tank 11 moves in the flow path f1 and flows into the mixer 31.
- the tank 12 is connected to the pump 22, and by the operation of the pump 22, the second liquid contained in the tank 12 moves in the flow path f2 and flows into the mixer 31. Then, the first liquid and the second liquid are mixed by the mixer 31 to become the first mixed liquid, which is sent to the flow path f4. In the process after this mixing, dehydration condensation occurs between the carboxylic acid contained in the first liquid and the isopropyl chloroformate contained in the second liquid to obtain a mixed acid anhydride (Step 1- 2). The first mixed solution containing the obtained acid anhydride flows into the mixer 32.
- the tank 13 is connected to the pump 23, and by the operation of the pump 23, the liquid contained in the tank 13 moves in the flow path f3, flows into the mixer 32, and is mixed with the first mixed liquid. And becomes a second mixed liquid, which is sent to the flow path f5.
- the mixed acid anhydride obtained in step 1-2 reacts with N-methylimidazole contained in the third liquid to become a cationic active species (see step 2 of the method for producing an amide). -2), and subsequently the obtained cationic active species reacts with the amine contained in the third liquid to obtain an amide (step 3-2 of the method for producing an amide).
- the manufactured second mixture liquid containing amide is stored in the tank 14.
- the area for heat exchange per volume of the reaction solution can be increased.
- the reaction time can be controlled by the flow rate and the length of the flow path. Therefore, the reaction solution can be strictly controlled, and as a result, the progress of unwanted side reactions can be minimized, and the yield of the target product can be improved.
- the cationic active species obtained in the above step 2 has an advantage that it can react even with an amine having low reactivity because of its high activity, but it is important to control the reaction. Further, even the acid anhydride obtained in the step 1 has a sufficiently high activity, so that control of the reaction is important. According to the flow-through reaction apparatus 1 according to the embodiment, the chances of compound collision are improved by continuously circulating the liquid through the flow path, the reaction can be advanced with higher efficiency, and side reactions can be suppressed. It will be easy. For example, since the acid anhydride generated in step 1 can be immediately reacted with N-methylimidazole (first base), the time during which the acid anhydride is in the activated state can be shortened, and isomerization, etc. It is possible to reduce the probability that the side reaction will occur.
- N-methylimidazole first base
- the form in which the liquids are mixed by the mixer has been illustrated, but since the mixing of the liquids can be achieved only by communicating the flow paths, the flow system of the embodiment is used.
- the reactor does not necessarily have to include a mixer.
- the amide production method of the second embodiment has been described as an example, but the first embodiment of the amide production method can be similarly performed.
- the first liquid contains a first carboxylic acid and a second carboxylic acid
- the second liquid contains phosgene or a phosgene equivalent that decomposes in the reaction system to produce phosgene
- the third liquid can include a first base, an acid and an amine.
- the first liquid contains carboxylic acid and DIEA
- the second liquid contains triphosgene (phosgene equivalent)
- the third liquid is 4-morpholinopyridine (first base), It may include hydrochloric acid (acid) and amine.
- the method for producing the amide of the embodiment can be carried out by a liquid phase method.
- the currently mainstream method for producing peptides (amides) is the solid phase method, and peptides are synthesized on the solid phase.
- the liquid phase method is suitable for large-scale synthesis and has high reactivity because the degree of freedom of molecules is increased.
- the liquid phase method is also effective for the reaction with amines having low reactivity.
- the five kinds of compounds to be reacted are stored in three tanks separately. However, for example, each of them is stored in a total of five separate tanks and mixed sequentially. Good.
- N-methylimidazole (first base) and amine are present in the same liquid in advance. That is, step 2 and step 3 may be carried out at the same time, which makes it easy to immediately react the highly reactive cationic active species generated in step 2 with the target amine, and the cationic active species are activated. The time in the activated state can be shortened, and the production of unwanted side reaction products can be effectively suppressed.
- N-methylimidazole (first base) and the acid are present in the same liquid in advance. As a result, unwanted epimer formation can be effectively suppressed.
- Example 1 Addition of HCl in mixed acid anhydride method [raw material]
- amino acid used as the carboxylic acid Fmoc-2-Phenylglycine-OH (commercially available), which is phenylglycine in which the amino group is protected by the Fmoc group, was used.
- amino acid used as an amine H-MePhe-OMe (commercially available product), which is phenylalanine in which a carboxyl group is protected by a methyl group and an amino group is methylated, was used.
- a coupling reaction was carried out between the amino acid used as the carboxylic acid and the amino acid used as the amine.
- the coupling reaction is a flow made up of a PTFE tube (inner diameter 0.8 mm, outer diameter 1.59 mm), a SUS tube (inner diameter 0.8 mm, outer diameter 1.58 mm), a SUS joint and a T-shaped mixer.
- a system reactor was used. The solution before the reaction was divided into three parts and prepared. The first solution was obtained by dissolving Fmoc-2-Phenylglycine-OH used as a carboxylic acid, DIEA, and N,N-dimethylbenzylamine used as a second base in 1,4-dioxane. ..
- the second solution was obtained by dissolving isopropyl chloroformate in 1,4-dioxane.
- the third solution was obtained by dissolving H-MePhe-OMe used as the amine, N-methylimidazole used as the first base, and HCl in a mixed solvent of 1,4-dioxane and MeCN.
- the molar concentration ratios in the flow reactor were 1.0 for H-MePhe-OMe (amine), 1.1 for Fmoc-2-Phenylglycine-OH (carboxylic acid), and 1.
- 1, N,N-dimethylbenzylamine was 0.055, isopropyl chloroformate was 1.05, N-methylimidazole was 0.1, and HCl was 0.155.
- the first solution and the second solution are mixed in a T-shaped mixer, and the mixed acid is obtained by reacting for 5 seconds in the flow reactor.
- An anhydride was obtained.
- the reaction solution containing the mixed acid anhydride and the third solution were mixed using a new T-shaped mixer, and reacted for 120 seconds in a flow reactor. All of these reactions were carried out at 60° C., and 10 seconds was set as the time for heat exchange before the solution before each reaction reached the mixer.
- Various solutions flowed out using a syringe pump. The flow rate of each pump was 2.0 mL/min for the first solution, 1.2 mL/min for the second solution, and 2.0 mL/min for the third solution.
- Step 1 of the method for producing an amide in Example 1 is shown below.
- R pg represents a phenylglycine side chain.
- R pg represents a phenylglycine side chain
- R p represents a phenylalanine side chain
- the yield of the target product was calculated from the weight of the target product isolated and purified. That is, the molar equivalent ratio of amine was set to 1.0, and the ratio of amine coupling was calculated from the weight of the isolated dipeptide.
- the epimer production rate was calculated by separating the isolated and purified amide isomers by HPLC and calculating the area ratio of the UV absorption intensities of the target amide and epimer.
- the target substance was detected at a retention time of 35.576 minutes (area ratio 73.58), and the epimer was detected at a retention time of 39.658 minutes (area ratio 26.42).
- the target dipeptide had a coupling yield of 86%, of which the epimer production rate was about 23%.
- Example 1 Although the ratio of the molar concentration of the carboxylic acid to the amine was 1:1.1 and the reaction time was as short as 120 seconds, a high coupling yield of 86% was obtained. Was achieved. In addition, despite the use of phenylglycine as a carboxylic acid, which is very likely to generate epimers, the epimer production rate could be significantly reduced as compared with Comparative Example 1 described later.
- a coupling reaction was carried out between the amino acid used as the carboxylic acid and the amino acid used as the amine.
- the coupling reaction is a flow made up of a PTFE tube (inner diameter 0.8 mm, outer diameter 1.59 mm), a SUS tube (inner diameter 0.8 mm, outer diameter 1.58 mm), a SUS joint and a T-shaped mixer.
- a system reactor was used. The solution before the reaction was divided into three parts and prepared. The first solution was obtained by dissolving Fmoc-2-Phenylglycine-OH used as a carboxylic acid, N-methylmorpholine, and DIEA in 1,4-dioxane.
- the second solution was obtained by dissolving isopropyl chloroformate in 1,4-dioxane.
- the third solution was obtained by dissolving H-MePhe-OMe used as an amine and 4-morpholinopyridine in 1,4-dioxane.
- the molar ratio of each in the flow reactor is 1.0 for H-MePhe-OMe (amine), 1.3 for Fmoc-2-Phenylglycine-OH (carboxylic acid), and 1 for DIEA. .3, N-methylmorpholine was 1.3, isopropyl chloroformate was 1.25, and 4-morpholinopyridine was 0.01.
- the first solution and the second solution are mixed in a T-shaped mixer, and the mixture is allowed to react in the flow reactor for 5 seconds to obtain a mixed acid anhydride. I got a thing.
- the reaction solution containing the mixed acid anhydride and the third solution were mixed using a new T-shaped mixer, and reacted for 150 seconds in a flow reactor. All of these reactions were carried out at 60° C., and 10 seconds was set as the time for heat exchange before the solution before each reaction reached the mixer.
- Various solutions flowed out using a syringe pump. The flow rate of each pump was 1.2 mL/min for the first solution, 1.2 mL/min for the second solution, and 2.0 mL/min for the third solution.
- the target dipeptide had a coupling yield of 93%, of which the epimer production rate was about 41%, and nearly half of them were epimers. Was found to be almost uncontrolled.
Abstract
Description
本願は、2018年12月25日に日本に出願された特願2018-241598に基づく優先権を主張し、その内容をここに援用する。
高活性な活性化剤を使って前記カルボキシル基を活性化させる方法として、酸塩化物法や酸無水物法がある。これら酸塩化物法や、酸無水物法は、活性化度の弱い縮合剤を使った活性法と比較して、活性化剤の構造が簡単であるため、単価が安く、更には活性化剤由来の副生成物の生成が少ない等の利点がある。
非特許文献1~2で開示される対称酸無水物法は、
カルボン酸同士の縮合反応による対称酸無水物の生成の第1のステップと、
前記対称酸無水物とアミンとのカップリング反応を行う第2のステップと、
を備える方法ということができる。
非特許文献3には、カルボン酸とクロロギ酸イソプロピルを第1のマイクロミキサーで混合し、混合酸無水物を短時間で合成し、続いて、合成した混合酸無水物がラセミ化しないよう、すぐさま混合酸無水物を含む溶液とアミンおよび触媒(塩基)を第二のマイクロミキサーで混合しアミド化を行うことが記載されている。
非特許文献3で開示される混合酸無水物法は、
カルボン酸とクロロギ酸エステルとを反応させて混合酸無水物を得る第1のステップと、
前記混合酸無水物に塩基を添加してアシルピリジニウム種を得る第2のステップと、
前記アシルピリジニウム種とアミンとのカップリング反応を行い、アミドを得る第3のステップと、
を備える方法ということができる。
すなわち、本発明の一態様は、下記のとおりである。
前記第1の塩基との反応及び/又はアミンとの反応を、酸を添加して行う、アミドの製造方法。
(2)第一のカルボン酸及び第二のカルボン酸を混合して得られた混合物を反応させた生成物と、又は
カルボン酸及びハロゲン化ギ酸エステルを混合して得られた混合物を反応させた生成物と、
第1の塩基と、酸と、アミンとを混合させることを含む、アミドの製造方法。
(3)ホスゲン、又は反応系内で分解してホスゲンを生成するホスゲン等価体を反応させて、前記カルボン酸同士を脱水縮合させる、前記(1)又は(2)に記載のアミドの製造方法。
(4)同じ種類の前記カルボン酸同士を脱水縮合させる、前記(1)~(3)のいずれか一つに記載のアミドの製造方法。
(5)前記ハロゲン化ギ酸エステルが、クロロギ酸イソプロピル、クロロギ酸イソブチル、クロロギ酸エチル、ブロモギ酸イソプロピル、ブロモギ酸イソブチル及びブロモギ酸エチルからなる群から選択されるいずれか一種以上である、前記(1)又は(2)に記載のアミドの製造方法。
(6)前記ハロゲン化ギ酸エステルを活性化する第2の塩基と、前記ハロゲン化ギ酸エステルとを反応させることを含む、前記(1)、(2)又は(5)に記載のアミドの製造方法。
(7)前記第2の塩基が、第三級アミン、4-メチルモルホリン、ピリジン、ピリジン誘導体、イミダゾール、イミダゾール誘導体及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群から選択されるいずれか一種以上である、前記(6)に記載のアミドの製造方法。
(8)前記酸は、ハロゲン化水素、過塩素酸、トリフルオロ酢酸、トリフルオロメタンスルホン酸、フルオロスルホン酸及びパラトルエンスルホン酸からなる群から選択されるいずれか一種以上である、前記(1)~(7)のいずれか一つに記載のアミドの製造方法。
(9)前記カルボン酸が、アミノ酸又はアミノ酸誘導体である、前記(1)~(8)のいずれか一つに記載のアミドの製造方法。
(10)前記カルボン酸が、フェニルグリシン、システイン、セリン、アスパラギン酸、ヒスチジン又はそれらの誘導体である、前記(1)~(9)のいずれか一つに記載のアミドの製造方法。
(11)前記第1の塩基が、ピリジン、ピリジン誘導体、イミダゾール、イミダゾール誘導体及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群より選択されるいずれか一種以上である、前記(1)~(10)のいずれか一つに記載のアミドの製造方法。
(12)前記第1の塩基が、4-モルホリノピリジン、N,N-ジメチル-4-アミノピリジン、4-ピロリジノピリジン、ピリジン、4-メトキシピリジン、イミダゾール、N-メチルイミダゾール及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群より選択されるいずれか一種以上である前記(1)~(11)のいずれか一つに記載のアミドの製造方法。
(13)前記アミンが、アミノ酸又はアミノ酸誘導体である、前記(1)~(12)のいずれか一つに記載のアミドの製造方法。
(14)前記アミンの求核性が、タンパク質を構成し遺伝情報としてコードされる20種のアミノ酸からバリン及びイソロイシンを除いた18種のアミノ酸の求核性よりも低い、前記(1)~(13)のいずれか一つに記載のアミドの製造方法。
(15)前記アミンが、バリン、イソロイシン若しくはN-アルキル化されたアミノ酸、又はそれらの誘導体である、前記(13)又は(14)に記載のアミドの製造方法。
(16)前記アミンと反応させることを、流通系反応装置で行う、前記(1)~(15)のいずれか一つに記載のアミドの製造方法。
(17)さらに、前記カルボン酸同士を反応させること、又は、前記カルボン酸と前記ハロゲン化ギ酸エステルとを反応させること、及び、前記第1の塩基と反応させることを、流通系反応装置で行う、前記(16)に記載のアミドの製造方法。
実施形態のアミドの製造方法は、以下の1)又は2)の方法である。
1)カルボン酸同士を脱水縮合させた後に、第1の塩基と反応させ、アミンと反応させてアミドを得ることを含み、前記第1の塩基との反応及び/又はアミンとの反応を、酸を添加して行う、アミドの製造方法。
2)カルボン酸とハロゲン化ギ酸エステルとを反応させた後に、第1の塩基と反応させ、アミンと反応させてアミドを得ることを含み、前記第1の塩基との反応及び/又はアミンとの反応を、酸を添加して行う、アミドの製造方法。
上記1)に係る、実施形態のアミドの製造方法は、第一のカルボン酸及び第二のカルボン酸を混合して得られた混合物を反応させた生成物と、第1の塩基と、酸と、アミンとを混合させることを含む、アミドの製造方法であってもよい。上記1)に係る実施形態のアミドの製造方法は、第一のカルボン酸、第二のカルボン酸及びホスゲン又は反応系内で分解してホスゲンを生成するホスゲン等価体を混合して得られた混合物を反応させた生成物と、第1の塩基と、酸と、アミンとを混合させることを含む方法であってもよい。ここで、第一のカルボン酸及び第二のカルボン酸を混合して得られた混合物を反応させた生成物は、第一のカルボン酸及び第二のカルボン酸を脱水縮合させた酸無水物を含むことができる。
上記2)に係る、実施形態のアミドの製造方法は、カルボン酸及びハロゲン化ギ酸エステルを混合して得られた混合物を反応させた生成物と、第1の塩基と、酸と、アミンとを混合させることを含む、アミドの製造方法であってもよい。上記2)に係る実施形態のアミドの製造方法は、カルボン酸、ハロゲン化ギ酸エステルを活性化する第2の塩基、及びハロゲン化ギ酸エステルを混合して得られた混合物を反応させた生成物と、第1の塩基と、酸と、アミンとを混合させることを含む、アミドの製造方法であってもよい。ここで、カルボン酸及びハロゲン化ギ酸エステルを混合して得られた混合物を反応させた生成物、又は、カルボン酸、ハロゲン化ギ酸エステルを活性化する第2の塩基及びハロゲン化ギ酸エステルを混合して得られた混合物を反応させた生成物は、混合酸無水物を含むことができる。
なお、当該第1の塩基は、カチオン性活性種を生成させるものであってよく、塩基(ただし、当該アミンを除く)であってよい。
なお、ここでいう混合とは、反応系に原料等の物質を添加する動作を指すものであり、反応系内でこれらが混合されたときには、原料等が添加前とは別の物質に変化していてもよい。
工程1:カルボン酸から、酸無水物を得る工程。
工程2:前記工程1で得られた前記酸無水物と、第1の塩基と、を反応させてカチオン性活性種を得る工程。
工程3:前記工程2で得られた前記カチオン性活性種と、アミンと、を反応させてアミドを製造する工程。
前記工程2の反応を、酸を添加して行う、
前記工程3の反応を、酸を添加して行う、又は
前記工程2及び前記工程3の反応を、酸を添加して行う。
なお、工程1の後に酸を添加すると、工程2の反応、又は、工程2及び工程3の反応が、酸の存在下での反応になるものと考えられる。酸の存在下とは、例えば、酸を添加した溶媒中のことを意味する。
なお、後述の実施例に示す方法においては、工程1の後に第1の塩基とともに酸を添加して、アミドの製造を行っている。
1’)カルボン酸同士を脱水縮合させた後に、酸を添加して第1の塩基と反応させ、アミンと反応させてアミドを得ることを含み、前記第1の塩基との反応及び/又はアミンとの反応を、酸を添加して行う、アミドの製造方法。
2’)カルボン酸とハロゲン化ギ酸エステルとを反応させた後に、酸を添加して第1の塩基と反応させ、アミンと反応させてアミドを得ることを含み、前記第1の塩基との反応及び/又はアミンとの反応を、酸を添加して行う、アミドの製造方法。
以下の実施形態では、主に、第1の塩基とともに酸を添加する場合について説明する。
第1の塩基とともに酸を添加する場合には、第1の塩基と酸との混合物を添加してもよい。
また、<第2実施形態>として、2’)における方法でカルボン酸とハロゲン化ギ酸エステルとを反応させて、混合酸無水物を得る場合を説明する。本実施形態において、上記工程1、工程2、及び工程3は、それぞれ工程1-2、工程2-2、及び工程3-2に対応する。
以下、工程1-1及び工程1-2の両方を指して、単に工程1と略することがあり、工程2-1及び工程2-2の両方を指して、単に工程2と略することがあり、工程3-1及び工程3-2の両方を指して、単に工程3と略することがある。
前記1’)の製造方法は、以下の工程1-1~3-1を含んでいてもよい。
工程1-1:カルボン酸同士を脱水縮合させて、酸無水物を得る工程。
工程2-1:酸を添加して、前記工程1-1で得られた前記酸無水物と、第1の塩基と、を反応させてカチオン性活性種を得る工程。
工程3-1:前記工程2-1で得られた前記カチオン性活性種と、アミンと、を反応させてアミドを製造する工程。
以下、上記の各工程について説明する。なお、本発明に係るアミドの製造方法の反応は、下記の各工程に例示される反応に限定されるものではない。
工程1-1は、カルボン酸同士を脱水縮合させて、酸無水物を得る工程である。
前記カルボン酸同士は、ホスゲン、又は反応系内で分解してホスゲンを生成するホスゲン等価体を反応させて、前記カルボン酸同士を脱水縮合させることができる。
カルボン酸は、分子の末端にカルボキシル基を有するものであればよく、下記一般式(1)で表すことができる。
塩基の存在下とは、例えば、塩基を添加した溶媒中のことを意味する。当該塩基の種類は、反応系内でカルボン酸の脱プロトン化を可能とするものであれば、特に限定されない。
したがって、R1とR2とが同一である場合には、反応系中に得られるアミドの種類が均一化され、目的とする種類の反応生成物の計画的な取得が容易であるという利点がある。
例えば、前記式(1-1)中のR0は、前記アミノ酸がアラニンの場合には「-CH3」であり、グリシンの場合には「-H」であり、バリンの場合には「-CH(CH3)2」であり、イソロイシンの場合には「-CH(CH3)CH2CH3」である。他のアミノ酸についても同様である。
前記式(1)及び(1)’がアミノ酸である場合、-R1及び-R2は、それぞれ、-CH(R0)NH2であってよい。
アミノ酸と実質的に同等の性質を有する場合の一例として、アミノ酸を基質とする酵素に取り込まれ得る、又はアミノ酸と結合する分子と結合し得る場合が挙げられる。
アミノ酸誘導体としては、アミノ酸において、1個以上の水素原子又は基が、それ以外の基(置換基)で置換されたものが挙げられる。アミノ酸誘導体の一例として、官能基が保護基で保護された、保護アミノ酸が挙げられる。保護基は、反応性の官能基を不活性化する作用を有する。保護基を脱保護して、保護された官能基を保護される前の状態に戻すことも可能である。ここで官能基が保護されたとは、前記官能基を構成する原子が、保護基で置換されていることをいう。保護基で保護される部位としては、アミノ基、カルボキシル基、及び側鎖からなる群から選択されるいずれか一種以上の部位が挙げられる。側鎖に含まれる官能基は1箇所又は2箇所以上が保護基で保護されていてもよい。当該工程1においては、カルボキシル基以外の反応性の官能基の反応を防止するよう、アミノ基及び/又は側鎖の官能基が保護されていることが好ましい。
カルバメート系の保護基としては、2-ベンジルオキシカルボニル基(-Z又は-Cbzと略されることがある。)、tert-ブトキシカルボニル基(-Bocと略されることがある。)、アリルオキシカルボニル基(-Allocと略されることがある。)、2,2,2-トリクロロエトキシカルボニル基(-Trocと略されることがある。)、2-(トリメチルシリル)エトキシカルボニル基(-Teocと略されることがある。)、9-フルオレニルメチルオキシカルボニル基(-Fmocと略されることがある。)、p-ニトロベンジルオキシカルボニル基(-Z(NO2)と略されることがある。)、p-ビフェニルイソプロピルオキシカルボニル基(-Bpocと略されることがある。)等が挙げられる。
スルホンアミド系の保護基としては、p-トルエンスルホニル基(-Ts又は-Tosと略されることがある。)や、2-ニトロベンゼンスルホニル基(-Nsと略されることがある。)、2,2,4,6,7-ペンタメチルジヒドロベンゾフラン-5-スルホニル(-Pbfと略されることがある。)、2,2,5,7,8-ペンタメチルクロマン-6-スルホニル(-Pmcと略されることがある。)、1,2-ジメチルインドール-3-スルホニル(-MISと略されることがある。)等が挙げられる。
工程2-1は、酸を添加して、前記工程1-1で得られた前記酸無水物と、第1の塩基と、を反応させてカチオン性活性種を得る工程である。
実施形態に係るアミドの製造方法の工程2-1は、下記一般式(2)で表される酸無水物と、Bで表される第1の塩基とを、Aで表される酸を添加して反応させて下記一般式(4)で表されるカチオン性活性種を得るものである。なお、当該反応においては、カチオン性活性種のカウンターアニオンとして、下記一般式(5)で表される化合物が生成される。
なお、ここで添加する酸はカルボン酸であってもよい。工程1-1では、予めカルボン酸を用いているが、工程1-1のカルボン酸は酸無水物となって活性種に変換されている。工程2-1でカルボン酸を添加したとしても、添加したカルボン酸が活性種とはなり難く、工程2-1で添加したカルボン酸は、アミドの構成単位として組み込まれ難いため、ここで添加する酸はカルボン酸であっても構わない。とはいえ、当該酸としては、カルボン酸を除く酸であることが好ましい。
収率の観点からは、当該酸としては、ハロゲン化水素、過塩素酸、トリフルオロ酢酸、トリフルオロメタンスルホン酸、フルオロスルホン酸及びパラトルエンスルホン酸からなる群から選択されるいずれか一種以上が好ましく、ハロゲン化水素がより好ましく、なかでも塩酸がより好ましい。
酸の添加により、アミドのエピマー生成を抑制できるとともに、カルボン酸とアミンとのカップリング反応速度が向上し、非常に高効率に、アミドを製造可能となる。
工程3-1は、前記工程2-1で得られた前記カチオン性活性種と、アミンと、を反応させてアミドを製造する工程である。
実施形態に係るアミドの製造方法の工程3-1は、下記一般式(4)で表されるカチオン性活性種と、下記一般式(6)で表されるアミンと、を反応させて下記一般式(7)で表されるアミドを得るものである。なお、下記式では示していないが、反応系内に上記工程2-1で添加された酸が存在していてもよい。
アミノ酸及びアミノ酸誘導体としては、前記カルボン酸において例示したものが挙げられる。
前記式(6)がアミノ酸である場合、-R3と-R4は、例えば、-Hと-CH(R0)COOHであってよい。
アミノ酸誘導体の一例として、官能基が保護基で保護された、保護アミノ酸が挙げられる。保護基で保護される部位としては、アミノ基、カルボキシル基、及び側鎖からなる群から選択されるいずれか一種以上の部位が挙げられる。側鎖に含まれる官能基は1箇所又は2箇所以上が保護基で保護されていてもよい。当該工程3-1においては、アミノ基以外の反応性の官能基の反応を防止するよう、カルボキシル基及び/又は側鎖の官能基が保護されていることが好ましい。
したがって、実施形態のアミドの製造方法は、求核性の低いアミンとの反応に好適である。求核性の低いアミンとは、具体的には、タンパク質を構成し遺伝情報としてコードされる20種のアミノ酸からバリン及びイソロイシンを除いた18種のアミノ酸の求核性よりも低いアミンであってもよく、より具体的には、バリン、イソロイシン若しくはN-アルキル化されたアミノ酸、又はそれらの誘導体を例示できる。N-アルキル化されたアミノ酸とは、α炭素に結合したアミノ基の1又は2つの水素原子がアルキル基に置換されているものであってよく、1又は2つの水素原子がメチル基に置換されたN-メチルアミノ酸が好ましい。これらの求核性の低いアミンは、従来、酸無水物法で合成に用いることが困難であった。しかし、実施形態のアミドの製造方法によれば、従来、酸無水物法で合成に用いることの困難であった求核性の低いアミンであっても使用することができ、かかる点においても実施形態のアミドの製造方法は画期的である。
前記2’)の製造方法は、以下の工程1-2~3-2を含んでいてもよい。
工程1-2:カルボン酸とハロゲン化ギ酸エステルとを反応させて、混合酸無水物を得る工程。
工程2-2:酸を添加して、前記工程1-2で得られた前記混合酸無水物と、第1の塩基と、を反応させてカチオン性活性種を得る工程。
工程3-2:前記工程2-2で得られた前記カチオン性活性種と、アミンと、を反応させてアミドを製造する工程。
以下、上記の各工程について説明する。なお、本発明に係るアミドの製造方法の反応は、下記の各工程に例示される反応に限定されるものではない。
工程1-2は、カルボン酸とハロゲン化ギ酸エステルとを反応させて、混合酸無水物を得る工程である。
前記脂肪族炭化水素基は、炭素数が1~20であってもよく、1~15であってもよい。
前記アルキル基は、直鎖状、分岐鎖状及び環状のいずれでもよい。環状である場合、前記アルキル基は、単環状又は多環状のいずれでもよい。前記アルキル基は、炭素数が1~20であってもよく、1~10であってもよく、1~5であってもよい。
前記第2の塩基は、前記ハロゲン化ギ酸エステルと反応してカチオン性活性種を生成させるものであり、工程1-2の生成物である前記混合酸無水物よりも前記ハロゲン化ギ酸エステルと優先的に反応するものが好ましく、第三級アミン、4-メチルモルホリン、ピリジン、ピリジン誘導体、イミダゾール、イミダゾール誘導体及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群より選択されるいずれか一種以上であることがより好ましい。ピリジン誘導体及びイミダゾール誘導体としては、前記工程2-1で例示したものが挙げられる。第三級アミンについてはアミンのN原子に結合する基の少なくとも一つがメチル基であることが好ましい。アミンのN原子に結合する基の二つがメチル基であるものはより好ましい。第三級アミンのN原子に結合する基の少なくとも一つをメチル基とすることで、N原子周囲の立体障害が小さくなり、前記ハロゲン化ギ酸エステルとの反応効率を向上させることができる。
上記の観点により、第2の塩基として好ましいものとしては、4-メチルモルホリン、N-メチルイミダゾール、N,N-ジメチルベンジルアミン、N,N-ジメチルブチルアミン、N,N-ジメチルアリルアミン、1,4-ジアザビシクロ[2,2,2]オクタン、N,N-ジメチル-4-アミノピリジン(DMAP)、N-メチルピペリジンが挙げられるが、これらに限られない。
収率の観点からは、N,N-ジメチルベンジルアミンを用いることが好ましい。反応系への過剰な第2の塩基の添加は、酸の添加による析出(塩の形成)が生じるおそれがある。その点、N,N-ジメチルベンジルアミンは、反応性が良好であるため、当量を下げても反応が進みやすいために析出の問題が生じ難い。そのため、N,N-ジメチルベンジルアミンは、析出の影響を受けやすい流通系反応装置を使用した製造方法に好適である。
工程2-2は、酸を添加して、前記工程1-2で得られた前記混合酸無水物と、第1の塩基と、を反応させてカチオン性活性種を得る工程である。
実施形態に係るアミドの製造方法の工程2-2は、下記一般式(II)で表される混合酸無水物と、Bで表される第1の塩基とを、Aで表される酸を添加して反応させて下記一般式(IV)で表されるカチオン性活性種を得るものである。なお、当該反応においては、カチオン性活性種のカウンターアニオンとして、下記一般式(V)で表される化合物が生成される。
前記第1の塩基としては、上記<第1実施形態>において例示したものが挙げられる。
工程3-2は、前記工程2-2で得られた前記カチオン性活性種と、アミンと、を反応させてアミドを製造する工程である。
実施形態に係るアミドの製造方法の工程3-2は、下記一般式(IV)で表されるカチオン性活性種と、下記一般式(VI)で表されるアミンと、を反応させて下記一般式(VII)で表されるアミドを得るものである。なお、下記式では示していないが、反応系内に上記工程2-2で添加された酸が存在していてもよい。
なお、上記工程2-2及び工程3-2において、式(V)に代えてアルコキシド(O-―R12)及びCO2が生成してもよい。
実施形態において、工程1~3の反応時の各化合物の使用量は、これらの化合物の種類を考慮し、目的とする反応に応じて適宜調節すればよい。
活性化したカルボン酸とアミンとの、反応系内のモル当量比(活性化したカルボン酸:アミン)は、10:1~1/10:1であってよく、5:1~1/5:1であってよく、3:1~1/3:1であってよい。活性化したカルボン酸とは、例えば前記一般式(4)又は(IV)で表される化合物である。実施形態のアミドの製造方法によれば、活性化したカルボン酸に対して、等量に近い比較的少量のアミンを反応させた場合であっても、高効率でアミドを製造可能である。
一つは、酸の添加により、反応系にプロトンが供給され、原料のカルボン酸に由来する中間体におけるラセミ化が抑制されることが考えられる。ラセミ化はプロトンが脱離したアニオンが安定的な構造であり、そこに再びプロトンが付加されるときに生じ得る。すなわち、ラセミ化は塩基性条件でより発生しやすく、酸を添加して中性条件に近づけることで、ラセミ化が抑制されると考えられる。
このことについては、酸の添加により、過剰な塩基が中和され、原料のカルボン酸に由来する中間体におけるラセミ化が抑制されることも考えられる。この場合のラセミ化は、原料カルボン酸に由来する中間体(例えばカチオン性活性種)が塩基と反応して生じた中間体で、プロトンが脱離したアニオンが安定的な構造である場合に、酸の添加によって塩基との反応を阻害することにより、ラセミ化が抑制されると考えられる。これは、工程2及び/又は工程3において副反応が抑制される場合と理解される。
あるいは、酸の添加による複合的要因により、カルボン酸とアミンとのカップリング反応の効率が高められたことで、相対的に、アミドのエピマー生成反応が抑制されることが考えられる。これは、工程3において副反応が抑制される場合と理解される。
実施形態のアミドの製造方法は、前記カルボン酸が、アミノ酸又はアミノ酸誘導体であり、且つ、前記アミンが、アミノ酸又はアミノ酸誘導体である場合、ペプチド又はタンパク質を合成できる。ペプチド又はタンパク質の製造方法は、アミドの製造方法に包含される。
上記工程3で得られたアミドを、工程1におけるカルボン酸として用い、工程1~3の後に、さらに工程1~3を繰り返すことで、ポリペプチド鎖を伸長させることができる。
即ち、前記カルボン酸としてはポリペプチドも含まれ、実施形態に係るアミノ酸又はアミノ酸誘導体(カルボン酸)として、ポリペプチドの構成単位としてC末端に位置するアミノ酸又はアミノ酸誘導体(カルボン酸)も含まれる。このように、実施形態のアミドの製造方法は、ペプチド又はタンパク質の製造方法として好適である。
実施形態のアミドの製造方法は、流通系反応装置を使用して実施することができる。流通系反応装置は、実施形態のアミドの製造方法における反応に用いられる原料又は中間体を含む流体を輸送する流路と、該流体を混合するための混合機と、を備えるものを例示できる。流通系反応装置の使用について、例えば、少なくとも前記工程3における、アミンとの反応を流通系反応装置で行うのであってもよく、前記工程2及び工程3における、第1の塩基と反応させ、アミンと反応させる反応を流通系反応装置で行うのであってもよく、前記工程1~3における、酸無水物を得た後に、第1の塩基と反応させ、アミンと反応させる反応を流通系反応装置で行うのであってもよい。なお、実施形態のアミドの製造方法は、流通系反応装置を使用して実施するものに限定されない。例えば、容積が小さく高速な攪拌速度が得られるバッチ容器を用いてもよい。バッチ容器の混合部の体積は、1~100mLであってもよく、5~50mLであってもよい。
図1は、流通系反応装置1の概略的な構成を示す模式図である。流通系反応装置1は、第1の液を収容するタンク11と、第2の液を収容するタンク12と、第3の液を収容するタンク13とを備える。
一例として、第1の液はカルボン酸を含み、第2の液はハロゲン化ギ酸エステルを含み、第3の液は第1の塩基、酸、及びアミンを含むことができる。他の一例として、第1の液はカルボン酸及びハロゲン化ギ酸エステルを活性化する第2の塩基を含み、第2の液はハロゲン化ギ酸エステルを含み、第3の液は第1の塩基、酸、及びアミンを含むことができる。より具体的な一例としては、図1に示すように、第1の液は、カルボン酸、N,N-ジメチルベンジルアミン(第2の塩基)及びDIEAを含み、第2の液はクロロギ酸イソプロピルを含み、第3の液はN-メチルイミダゾール(第1の塩基)、塩酸(酸)及びアミンを含む。
流通系反応装置の使用について、例えば、少なくとも第1の液と第2の液との混合物と、第3の液との混合を流通系反応装置で行うのであってもよく、更には、第1の液と第2の液との混合を流通系反応装置で行うのであってもよい。
上記の流路の内径とは、流路の長さ方向と直角に交わる方向での流路断面における、流路内部分(流体が通る部分)の直径とすることができる。流路内部分の形状が真円形でない場合には、上記の流路の内径とは、上記流路内部分の形状を面積基準で真円換算したときの直径とすることができる。
タンク11,12,13,14、混合機31,32及び流路f1,f2,f3,f4,f5は、一例として、プラスチックやエラストマー等の樹脂や、ガラス材、金属、セラミックなどで形成されている。
実施形態に係る流通系反応装置1によれば、流路を通じて液を連続的に流通させることで化合物の衝突の機会が向上し、より高効率に反応を進めることができ、副反応の抑制も容易となる。例えば、工程1で生じた酸無水物を、すぐさまN-メチルイミダゾール(第1の塩基)と反応させることが可能となるので、酸無水物が活性化状態でいる時間を短くでき、異性化等の副反応が生じる確率を低減できる。
なお、上記に例示した流通系反応装置では、第2実施形態のアミドの製造方法を例に説明したが、アミドの製造方法の第1実施形態も、同様に実施することができる。
一例として、第1の液は第一のカルボン酸及び第二のカルボン酸を含み、第2の液はホスゲン又は反応系内で分解してホスゲンを生成するホスゲン等価体を含み、第3の液は第1の塩基、酸及びアミンを含むことができる。より具体的な一例としては、第1の液はカルボン酸及びDIEAを含み、第2の液はトリホスゲン(ホスゲン等価体)を含み、第3の液は4-モルホリノピリジン(第1の塩基)、塩酸(酸)及びアミンを含むことができる。
しかし、上記実施形態の第3の液として示したように、N-メチルイミダゾール(第1の塩基)とアミンとは、あらかじめ同じ液中に存在させることが好ましい。即ち、工程2及び工程3は同時に行ってもよく、これにより、工程2で生じた反応性の高いカチオン性活性種を、すぐさま目的のアミンと反応させることが容易となり、カチオン性活性種が活性化状態でいる時間を短くでき、望まない副反応物の生成を効果的に抑制できる。
〔原料〕
カルボン酸として用いたアミノ酸には、アミノ基がFmoc基によって保護された、フェニルグリシンである、Fmoc-2-Phenylglycine-OH(市販品)を用いた。アミンとして用いたアミノ酸には、カルボキシル基がメチル基で保護され、かつアミノ基がメチル化されたフェニルアラニンである、H-MePhe-OMe(市販品)を用いた。
カルボン酸として用いたアミノ酸と、アミンとして用いたアミノ酸とのカップリング反応を行った。カップリング反応は、PTFE製チューブ(内径0.8mm,外径1.59mm)とSUS製チューブ(内径0.8mm、外径1.58mm)とSUS製継手とT字型ミキサーで構成された流通系反応装置を用いた。反応前の溶液は3つに分けて調整した。第1の溶液は、カルボン酸として用いたFmoc-2-Phenylglycine-OHと、DIEAと、第2の塩基として用いたN,N-ジメチルベンジルアミンとを1,4-ジオキサンに溶解して得た。第2の溶液は、クロロギ酸イソプロピルを1,4-ジオキサンに溶解して得た。第3の溶液は、アミンとして用いたH-MePhe-OMeと、第1の塩基として用いたN-メチルイミダゾールと、HClとを1,4-ジオキサンとMeCNの混合溶媒に溶解して得た。流通系反応装置中でのそれぞれのモル濃度の比は、H-MePhe-OMe(アミン)1.0に対して、Fmoc-2-Phenylglycine-OH(カルボン酸)が1.1、DIEAが1.1、N,N-ジメチルベンジルアミンが0.055、クロロギ酸イソプロピルが1.05、N-メチルイミダゾールが0.1、HClが0.155とした。
目的物の単離にはシリカゲルカラムクロマトグラフィーを用い、NMR解析にて同定した。
得られたジペプチドのNMRデータを以下に示す。
1H NMR(500MHz、CDCl3):δ7.78-7.70(m、2H)、7.59-7.51(m、2H)、7.46-6.84(m、14H)、6.28(d、J=7.5Hz、1H)、5.48(d、J=7.5Hz、1H)、5.17-5.11(m、1H),4.36-4.23(m、2H)、4.20-4.14(m、1H)、3.68(s、3H)、3.42-3.35(m、1H)、3.05-2.95(m、1H)、2.70(s、3H)
〔原料〕
カルボン酸として用いたアミノ酸には、アミノ基がFmoc基によって保護された、フェニルグリシンである、Fmoc-2-Phenylglycine-OH(市販品)を用いた。アミンとして用いたアミノ酸には、カルボキシル基がメチル基で保護され、かつアミノ基がメチル化されたフェニルアラニンである、H-MePhe-OMe(市販品)を用いた。
カルボン酸として用いたアミノ酸と、アミンとして用いたアミノ酸とのカップリング反応を行った。カップリング反応は、PTFE製チューブ(内径0.8mm,外径1.59mm)とSUS製チューブ(内径0.8mm、外径1.58mm)とSUS製継手とT字型ミキサーで構成された流通系反応装置を用いた。反応前の溶液は3つに分けて調製した。第1の溶液は、カルボン酸として用いたFmoc-2-Phenylglycine-OHと、N-メチルモルホリンと、DIEAとを1,4-ジオキサンに溶解して得た。第2の溶液は、クロロギ酸イソプロピルを1,4-ジオキサンに溶解して得た。第3の溶液はアミンとして用いたH-MePhe-OMeと、4-モルホリノピリジンとを1,4-ジオキサンに溶解して得た。流通系反応装置中でのそれぞれのモル濃度の比は、H-MePhe-OMe(アミン)が1.0に対して、Fmoc-2-Phenylglycine-OH(カルボン酸)が1.3、DIEAが1.3、N-メチルモルホリンが1.3、クロロギ酸イソプロピルが1.25、4-モルホリノピリジンが0.01とした。
実施例1と同様の方法により行った。
反応後の生成物を分析した結果、目的物であるジペプチドは、カップリング収率が93%であり、そのうちエピマー生成率は41%程度であり、半数近くがエピマーであったことから、エピマー生成がほとんど抑制されていないことが判明した。
Claims (17)
- カルボン酸同士を脱水縮合させた後に、又は、カルボン酸とハロゲン化ギ酸エステルとを反応させた後に、第1の塩基と反応させ、アミンと反応させてアミドを得ることを含み、
前記第1の塩基との反応及び/又はアミンとの反応を、酸を添加して行う、アミドの製造方法。 - 第一のカルボン酸及び第二のカルボン酸を混合して得られた混合物を反応させた生成物と、又は
カルボン酸及びハロゲン化ギ酸エステルを混合して得られた混合物を反応させた生成物と、
第1の塩基と、酸と、アミンとを混合させることを含む、アミドの製造方法。 - ホスゲン、又は反応系内で分解してホスゲンを生成するホスゲン等価体を反応させて、前記カルボン酸同士を脱水縮合させる、請求項1又は2に記載のアミドの製造方法。
- 同じ種類の前記カルボン酸同士を脱水縮合させる、請求項1~3のいずれか一項に記載のアミドの製造方法。
- 前記ハロゲン化ギ酸エステルが、クロロギ酸イソプロピル、クロロギ酸イソブチル、クロロギ酸エチル、ブロモギ酸イソプロピル、ブロモギ酸イソブチル及びブロモギ酸エチルからなる群から選択されるいずれか一種以上である、請求項1又は2に記載のアミドの製造方法。
- 前記ハロゲン化ギ酸エステルを活性化する第2の塩基と、前記ハロゲン化ギ酸エステルとを反応させることを含む、請求項1、2又は5に記載のアミドの製造方法。
- 前記第2の塩基が、第三級アミン、4-メチルモルホリン、ピリジン、ピリジン誘導体、イミダゾール、イミダゾール誘導体及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群から選択されるいずれか一種以上である、請求項6に記載のアミドの製造方法。
- 前記酸は、ハロゲン化水素、過塩素酸、トリフルオロ酢酸、トリフルオロメタンスルホン酸、フルオロスルホン酸及びパラトルエンスルホン酸からなる群から選択されるいずれか一種以上である、請求項1~7のいずれか一項に記載のアミドの製造方法。
- 前記カルボン酸が、アミノ酸又はアミノ酸誘導体である、請求項1~8のいずれか一項に記載のアミドの製造方法。
- 前記カルボン酸が、フェニルグリシン、システイン、セリン、アスパラギン酸、ヒスチジン又はそれらの誘導体である、請求項1~9のいずれか一項に記載のアミドの製造方法。
- 前記第1の塩基が、ピリジン、ピリジン誘導体、イミダゾール、イミダゾール誘導体及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群より選択されるいずれか一種以上である、請求項1~10のいずれか一項に記載のアミドの製造方法。
- 前記第1の塩基が、4-モルホリノピリジン、N,N-ジメチル-4-アミノピリジン、4-ピロリジノピリジン、ピリジン、4-メトキシピリジン、イミダゾール、N-メチルイミダゾール及び1,4-ジアザビシクロ[2,2,2]オクタンからなる群より選択されるいずれか一種以上である請求項1~11のいずれか一項に記載のアミドの製造方法。
- 前記アミンが、アミノ酸又はアミノ酸誘導体である、請求項1~12のいずれか一項に記載のアミドの製造方法。
- 前記アミンの求核性が、タンパク質を構成し遺伝情報としてコードされる20種のアミノ酸からバリン及びイソロイシンを除いた18種のアミノ酸の求核性よりも低い、請求項1~13のいずれか一項に記載のアミドの製造方法。
- 前記アミンが、バリン、イソロイシン若しくはN-アルキル化されたアミノ酸、又はそれらの誘導体である、請求項13又は14に記載のアミドの製造方法。
- 前記アミンと反応させることを、流通系反応装置で行う、請求項1~15のいずれか一項に記載のアミドの製造方法。
- さらに、前記カルボン酸同士を反応させること、又は、前記カルボン酸と前記ハロゲン化ギ酸エステルとを反応させること、及び、前記第1の塩基と反応させることを、流通系反応装置で行う、請求項16に記載のアミドの製造方法。
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SHINICHIRO FUSE , YUTO MIFUNE , HIROYUKI NAKAMURA , HIROSHI TANAKA: "Total synthesis of feglymycin based on a linear/convergent hybrid approach using micro-flow amide bond formation", NATURE COMMUNICATIONS, vol. 7, 13491, 28 November 2016 (2016-11-28), pages 1 - 7, XP055662919, DOI: 10.1038/ncomms13491 * |
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EP3904317A4 (en) | 2022-09-21 |
EP3904317A1 (en) | 2021-11-03 |
US20220055984A1 (en) | 2022-02-24 |
AU2019415174B2 (en) | 2022-08-11 |
CN113227019A (zh) | 2021-08-06 |
JPWO2020137545A1 (ja) | 2021-11-04 |
AU2019415174A1 (en) | 2021-07-29 |
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