Method for producing gluconic acid derivatives

Abstract

The present invention relates to a method for producing a gluconic acid derivative. The subject of the present invention is to provide a method for producing a gluconic acid derivative such as 2,3,4,5,6-pentaacetylgluconic acid in a short process and with high yield. The present invention provides a method for producing a compound (I) represented by the following formula (I), the method comprising the following steps: adding a compound (II) represented by the following formula (II), an acid anhydride (III) represented by the following formula (III), an acid chloride (IV) represented by the following formula (IV), and zinc chloride to a reaction vessel, and mixing the compound (II), the acid anhydride (III), the acid chloride (IV) and the zinc chloride.

Description

Technical Field

[0001] The present invention relates to a method for producing a gluconic acid derivative. Background Art

[0002] As shown in the following reaction formula, there is known a method in which zinc chloride and acetic anhydride are brought into contact with gluconolactone (3) to obtain (2R,3S,4R,5R)-2,3,4,6-tetraacetoxy-5-hydroxyhexanoic acid (4), and then zinc chloride and acetic anhydride are brought into contact with (2R,3S,4R,5R)-2,3,4,6-tetraacetoxy-5-hydroxyhexanoic acid (4) to produce (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) (Patent Document 1). It should be noted that in the following reaction formula, "Ac" represents an acetyl group.

[0003] [Chemical formula 1]

[0004]

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: U.S. Patent No. 4,567,285 Summary of the invention

[0008] Problems to be solved by the invention

[0009] An object of the present invention is to provide a method for producing a gluconic acid derivative such as 2,3,4,5,6-pentaacetylgluconic acid in a short process and at a high yield.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, the present invention provides the following means.

[0012] [1] A method for producing a compound (I) represented by the following formula (I), the method comprising the following steps:

[0013] A compound (II) represented by the following formula (II), an acid anhydride (III) represented by the following formula (III), an acid chloride (IV) represented by the following formula (IV), and zinc chloride are added to a reaction container, and the compound (II), the acid anhydride (III), the acid chloride (IV), and the zinc chloride are mixed.

[0014] [Chemical formula 2]

[0015]

[0016] [In the formula, R represents an alkyl group which may have one or more substituents, an aryl group which may have one or more substituents, or an arylalkyl group which may have one or more substituents.]

[0017] [Chemical formula 3]

[0018]

[0019] [Wherein, X represents a hydrogen atom or an alkali metal atom.]

[0020] [Chemical formula 4]

[0021]

[0022] [Wherein, R has the same meaning as above.]

[0023] [Chemical formula 5]

[0024]

[0025] [Wherein, R has the same meaning as above.]

[0026] [2] The method according to [1], wherein in the step, an acid (V) represented by the following formula (V) is further added to the reaction vessel, and the compound (II), the acid anhydride (III), the acid chloride (IV), the zinc chloride and the acid (V) are mixed.

[0027] [Chemical formula 6]

[0028]

[0029] [Wherein, R has the same meaning as above.]

[0030] Effects of the Invention

[0031] According to the present invention, there is provided a method for producing a gluconic acid derivative such as 2,3,4,5,6-pentaacetylgluconic acid in a short process and with a high yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] [ Figure 1 ] Figure 1 To show the (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid obtained in Example 1 1 Figure 1. H NMR spectrum.

[0033] [ Figure 2 ] Figure 2 To show the (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid obtained in Example 1 13 Figure 1. C NMR spectrum.

[0034] [ Figure 3 ] Figure 3 This is a diagram showing the IR spectrum of (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid obtained in Example 1. DETAILED DESCRIPTION

[0035] The present invention will be described below. Two or more embodiments described in this specification may be combined, and the combination of two or more embodiments is also included in the present invention.

[0036] 《Explanation of Terminology》

[0037] The following are terms used in this specification. Unless otherwise specified, the following description applies throughout this specification. It should be noted that, unless otherwise specified, the expression "value A to value B" means value A or more and value B or less.

[0038] Halogen Atom

[0039] The halogen atom is selected from a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0040] alkyl

[0041] The number of carbon atoms in the alkyl group is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 12, and even more preferably 1 to 10 (e.g., 1 to 8, 1 to 6, 1 to 5, 1 to 4, 1 to 3, or 1 to 2). The alkyl group may be linear or branched. The number of carbon atoms in a linear alkyl group is 1 or more, and the number of carbon atoms in a branched alkyl group is 3 or more.

[0042] Aryl

[0043] The aryl group is, for example, a monocyclic or polycyclic (e.g., bicyclic or tricyclic) aromatic hydrocarbon ring group having 4 to 14 carbon atoms, preferably 6 to 14 carbon atoms, and more preferably 6 to 10 carbon atoms. The polycyclic group is preferably a condensed ring group. Examples of the aryl group include phenyl and naphthyl. The aryl group is preferably phenyl.

[0044] Heterocycloalkyl

[0045] Heterocycloalkyl is a monocyclic saturated aliphatic heterocyclic group, in which, as a ring-constituting atom, in addition to carbon atoms, one or more heteroatoms independently selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms are contained. Saturated aliphatic heterocyclic groups are aliphatic heterocyclic groups whose rings are composed only of saturated bonds. The number of heteroatoms is, for example, 1 to 4, preferably 1 to 3, and more preferably 1 or 2. The number of members of heterocycloalkyl is, for example, 3 to 8, preferably 4 to 7, more preferably 5 to 7, and further preferably 5 or 6. As heterocycloalkyl, for example, heterocycloalkyl containing 1 to 2 oxygen atoms, heterocycloalkyl containing 1 to 2 sulfur atoms, heterocycloalkyl containing 1 to 2 oxygen atoms and 1 to 2 sulfur atoms, heterocycloalkyl containing 1 to 4 nitrogen atoms, heterocycloalkyl containing 1 to 3 nitrogen atoms and 1 to 2 sulfur atoms and / or 1 to 2 oxygen atoms, etc. can be cited. Heterocycloalkyl preferably contains an oxygen atom as a heteroatom. Examples of the heterocycloalkyl group include aziridinyl, oxirane, thiirane, azetidinyl, oxetanyl, thietanyl, tetrahydrothiophenyl, tetrahydrofuranyl, pyrrolidinyl, imidazolidinyl, oxazolidinyl, pyrazolidinyl, thiazolidinyl, tetrahydroisothiazolyl, tetrahydrooxazolyl, tetrahydroisoxazolyl, piperidinyl, piperazinyl, tetrahydropyranyl, tetrahydrothiopyranyl, morpholinyl, thiomorpholinyl (the sulfur atom on the ring may be oxidized), azepanyl, diazepanyl, oxetanyl, azooctanyl, and diazaoctanyl.

[0046] In one embodiment, heterocycloalkyl is tetrahydrofuranyl.In another embodiment, heterocycloalkyl is tetrahydropyranyl.

[0047] Halogenated alkyl

[0048] The haloalkyl group is an alkyl group having one or more halogen atoms, and the description of the alkyl group is as described above. The number of halogen atoms contained in the haloalkyl group is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

[0049] Halogenated aryl

[0050] The halogenated aryl group is an aryl group having one or more halogen atoms, and the description of the aryl group is as described above. The number of halogen atoms contained in the halogenated aryl group is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

[0051] Arylalkyl

[0052] The arylalkyl group is an alkyl group having one or more aryl groups, and the descriptions of the alkyl group and the aryl group are as described above. The number of aryl groups contained in the arylalkyl group is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

[0053] Alkylcarbonyl and arylcarbonyl

[0054] The alkylcarbonyl group and the arylcarbonyl group are groups represented by the formula: -CO-alkyl and the formula: -CO-aryl, respectively, and the descriptions of the alkyl group and the aryl group are as described above.

[0055] Alkyloxy, haloalkyloxy and arylalkyloxy

[0056] The alkyloxy group, the haloalkyloxy group and the arylalkyloxy group are groups represented by the formula: -O-alkyl, the formula: -O-haloalkyl and the formula: -O-arylalkyl, respectively, and the descriptions of the alkyl group, the haloalkyl group and the arylalkyl group are as described above.

[0057] Arylalkyloxyalkyl

[0058] The arylalkyloxyalkyl group is an alkyl group having one or more arylalkyloxy groups, and the alkyl group and the arylalkyloxy group are as described above. The number of arylalkyloxy groups contained in the arylalkyloxyalkyl group is, for example, 1 to 3, preferably 1 or 2, and more preferably 1.

[0059] Alkylthio and haloalkylthio

[0060] The alkylthio group and the haloalkylthio group are groups represented by the formula: -S-alkyl and the formula: -S-haloalkyl, respectively, and the descriptions of the alkyl group and the haloalkyl group are as described above.

[0061] Alkyloxycarbonyl

[0062] The alkyloxycarbonyl group is a group represented by the formula: -CO-O-alkyl, and the description of the alkyl group is as described above.

[0063] Amino

[0064] Amino group is of formula: -NH 2 Represents a group (primary amino group).

[0065] Monoalkylamino

[0066] A monoalkylamino group is of the formula: -NH(-Q 1 )[where Q 1 represents an alkyl group.] The group represented by [ is as described above for the alkyl group. 1 The number of carbon atoms in the alkyl group represented by is preferably 1 to 6, more preferably 1 to 4, further preferably 1 to 3, further preferably 1 or 2.

[0067] Dialkylamino

[0068] The dialkylamino group is of the formula: -N(-Q 2 )(-Q 3 )[where Q2 and Q 3 Each independently represents an alkyl group. The group represented by ] has the same meaning as described above for the alkyl group. 2 or Q 3 The number of carbon atoms in the alkyl group represented by is preferably 1 to 6, more preferably 1 to 4, further preferably 1 to 3, further preferably 1 or 2.

[0069] Alicyclic amino

[0070] The alicyclic amino group is, for example, a 5- or 6-membered alicyclic amino group. As the 5- or 6-membered alicyclic amino group, for example, morpholino, thiomorpholino, pyrrolidin-1-yl, pyrazolidin-1-yl, imidazolidin-1-yl, piperidin-1-yl, etc. can be cited. The alicyclic amino group may include, in addition to the nitrogen atom having the connecting bond of the alicyclic amino group, a heteroatom (for example, 1 heteroatom) independently selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom. The alicyclic amino group is preferably a morpholino group.

[0071] Aminocarbonyl, monoalkylaminocarbonyl, dialkylaminocarbonyl and alicyclic aminocarbonyl

[0072] The aminocarbonyl group, monoalkylaminocarbonyl group, dialkylaminocarbonyl group and alicyclic aminocarbonyl group are groups represented by the formula: -CO-amino group, the formula: -CO-monoalkylamino group, the formula: -CO-dialkylamino group and the formula: -CO-alicyclic amino group, respectively, and the monoalkylamino group, the dialkylamino group and the alicyclic amino group are as described above.

[0073] More than one substituent

[0074] "One or more" preferably means 1 to 3, and more preferably means 1 or 2. One or more substituents can be each independently selected from Substituent Group α described below.

[0075] Substituent group α

[0076] Substituent group α consists of the following substituents.

[0077] (α-1) Halogen atom

[0078] (α-2) Nitrile

[0079] (α-3) Nitro

[0080] (α-4)Amino

[0081] (α-5) alkyl

[0082] (α-6)Halogenated Alkyl

[0083] (α-7)monoalkylamino

[0084] (α-8)Dialkylamino

[0085] (α-9) alicyclic amino

[0086] (α-10)alkyloxycarbonyl

[0087] (α-11)aminocarbonyl

[0088] (α-12)Monoalkylaminocarbonyl

[0089] (α-13)Dialkylaminocarbonyl

[0090] (α-14)Alicyclic aminocarbonyl

[0091] (α-15) Hydroxyl group which may be protected by a protecting group

[0092] (α-16) Thiol group which may be protected by a protecting group

[0093] In (α-5), the number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, further preferably 1 to 6, further preferably 1 to 5, further preferably 1 to 4, further preferably 1 to 3, further preferably 1 or 2.

[0094] In (α-6), the number of carbon atoms in the haloalkyl group is preferably 1 to 10, more preferably 1 to 8, further preferably 1 to 6, further preferably 1 to 5, further preferably 1 to 4, further preferably 1 to 3, further preferably 1 or 2. The number of halogen atoms contained in the haloalkyl group is preferably 1 to 3, more preferably 1 or 2, further preferably 1.

[0095] (α-15) Hydroxyl group which may be protected by a protecting group

[0096] The hydroxy protecting group is preferably a group that can protect the hydroxyl group when implementing the target reaction and can be separated from the hydroxyl group after the target reaction ends. As the hydroxy protecting group, for example, alkylcarbonyl type protecting group, arylcarbonyl type protecting group, arylalkyl type protecting group, alkyl type protecting group, arylalkyloxyalkyl type protecting group, alkyloxyalkyl type protecting group, silyl type protecting group, oxycarbonyl type protecting group, acetal type protecting group, aryl type protecting group etc. can be enumerated. These protecting groups can have more than one halogen atom.

[0097] Examples of the alkylcarbonyl type protecting group include alkylcarbonyl groups having 2 to 10 carbon atoms which may have one or more substituents. The substituent may be selected from, for example, a halogen atom, a nitro group, a cyano group, a phenyl group, an alkyl group having 1 to 10 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and further preferably 1 to 4 carbon atoms), an alkyloxy group having 1 to 10 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and further preferably 1 to 4 carbon atoms), and an alkyloxycarbonyl group having 2 to 11 carbon atoms (preferably 2 to 9 carbon atoms, more preferably 2 to 7 carbon atoms, and further preferably 2 to 5 carbon atoms). Examples of the alkylcarbonyl group having 2 to 10 carbon atoms which may have one or more substituents include acetyl, propionyl, butyryl, isopropionyl, and pivaloyl. The alkylcarbonyl-type protecting group is preferably an alkylcarbonyl group having 2 to 5 carbon atoms, more preferably an acetyl group or a pivaloyl group, and still more preferably an acetyl group.

[0098] As the arylcarbonyl type protecting group, for example, an arylcarbonyl group having 7 to 11 carbon atoms which may have one or more substituents can be mentioned. Specific examples of the substituent are the same as those of the alkylcarbonyl type protecting group. As the arylcarbonyl group having 7 to 11 carbon atoms which may have one or more substituents, for example, a benzoyl group, a 4-nitrobenzoyl group, a 4-methyloxybenzoyl group, a 4-methylbenzoyl group, a 4-tert-butylbenzoyl group, a 4-fluorobenzoyl group, a 4-chlorobenzoyl group, a 4-bromobenzoyl group, a 4-phenylbenzoyl group, a 4-methyloxycarbonylbenzoyl group, and the like can be mentioned.

[0099] As the arylalkyl type protecting group, for example, an arylalkyl group having 7 to 11 carbon atoms which may have one or more substituents can be mentioned. Specific examples of the substituent are the same as those of the alkylcarbonyl type protecting group. As the arylalkyl group having 7 to 11 carbon atoms which may have one or more substituents, for example, benzyl, 1-phenylethyl, diphenylmethyl, 1,1-diphenylethyl, naphthylmethyl, trityl, etc. can be mentioned. The arylalkyl type protecting group is preferably a benzyl group.

[0100] As the alkyl type protecting group, for example, an alkyl group having 1 to 10 carbon atoms which may have one or more substituents can be mentioned. Specific examples of the substituent are the same as those of the alkylcarbonyl type protecting group. The alkyl type protecting group is preferably an alkyl group having 1 to 5 carbon atoms which may have one or more substituents, more preferably a methyl group, an ethyl group, or a tert-butyl group, and even more preferably a methyl group.

[0101] As the arylalkyloxyalkyl type protecting group, for example, there can be mentioned arylalkyloxyalkyl groups such as arylalkyloxymethyl groups having 8 to 12 carbon atoms which may have one or more substituents, arylalkyloxyethyl groups having 9 to 13 carbon atoms which may have one or more substituents, and arylalkyloxypropyl groups having 10 to 14 carbon atoms which may have one or more substituents. Specific examples of the substituents are the same as those of the alkylcarbonyl type protecting group. The arylalkyloxyalkyl type protecting group is, for example, a benzyloxymethyl group which may have one or more substituents, preferably a benzyloxymethyl group which may be substituted with a halogen atom, a nitro group, a cyano group, a methyl group, or a methyloxy group, and more preferably a benzyloxymethyl group.

[0102] As the alkyloxyalkyl type protecting group, for example, there can be mentioned alkyloxyalkyl groups such as alkyloxymethyl groups having 2 to 10 carbon atoms which may have one or more substituents, alkyloxyethyl groups having 3 to 10 carbon atoms which may have one or more substituents, and alkyloxypropyl groups having 4 to 10 carbon atoms which may have one or more substituents. Specific examples of the substituents are the same as those of the alkylcarbonyl type protecting group. The alkyloxyalkyl type protecting group is preferably an alkyloxymethyl group having 2 to 10 carbon atoms which may have one or more substituents, more preferably an alkyloxymethyl group having 2 to 6 carbon atoms which may have a halogen atom, a nitro group, a cyano group, a methyloxy group or an ethyloxy group, and even more preferably a methyloxymethyl group.

[0103] As a silyl type protecting group, for example, a silyl group having a functional group selected from an alkyl group having 1 to 10 carbon atoms which may have one or more substituents, an arylalkyl group having 7 to 11 carbon atoms which may have one or more substituents, and an aryl group having 6 to 10 carbon atoms which may have one or more substituents can be cited. Specific examples of the substituent are the same as those of the alkylcarbonyl type protecting group. The silyl type protecting group is preferably a silyl group having a functional group selected from an alkyl group having 1 to 10 carbon atoms and an aryl group having 6 to 10 carbon atoms, more preferably a silyl group having a functional group selected from an alkyl group having 1 to 5 carbon atoms and a phenyl group, and further preferably a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, or a tert-butyldiphenylsilyl group.

[0104] As the oxycarbonyl type protecting group, for example, an alkyloxycarbonyl group having 2 to 10 carbon atoms which may have one or more substituents, an alkenyloxycarbonyl group having 3 to 10 carbon atoms which may have one or more substituents, an arylalkyloxycarbonyl group having 8 to 12 carbon atoms which may have one or more substituents, etc. can be mentioned. Specific examples of the substituents are the same as those of the alkylcarbonyl type protecting group. The oxycarbonyl type protecting group is preferably an alkyloxycarbonyl group having 2 to 6 carbon atoms, an alkenyloxycarbonyl group having 3 to 6 carbon atoms, or a benzyloxycarbonyl group, and more preferably a methyloxymethyl group, an allyloxycarbonyl group, or a benzyloxycarbonyl group.

[0105] Examples of the acetal type protecting group include tetrahydrofuranyl and tetrahydropyranyl.

[0106] Examples of the aryl type protecting group include aryl groups such as phenyl.

[0107] The hydroxyl group protected by the protecting group is preferably a group represented by the formula: -OQ. Q represents an alkyl group, a halogenated alkyl group, an aryl group, a halogenated aryl group, a heterocycloalkyl group, an alkylcarbonyl group, an arylcarbonyl group or an arylalkyl group. The number of carbon atoms of the group represented by the formula: -OQ is preferably 1 to 10, more preferably 1 to 8. Q is preferably an alkyl group, a heterocycloalkyl group, an alkylcarbonyl group or an arylalkyl group, more preferably an ethyl group, a tetrahydrofuranyl group, an acetyl group or a benzyl group.

[0108] (α-16) Thiol group which may be protected by a protecting group

[0109] The thiol protecting group is preferably a group that can protect the thiol group when the target reaction is carried out and can be separated from the thiol group after the target reaction is completed. As the thiol protecting group, for example, an alkylcarbonyl type protecting group, an arylcarbonyl type protecting group, an arylalkyl type protecting group, an alkyl type protecting group, an arylalkyloxyalkyl type protecting group, an alkyloxyalkyl type protecting group, a silyl type protecting group, an oxycarbonyl type protecting group, an acetal type protecting group, an aryl type protecting group, etc. can be cited. These protecting groups can have more than one halogen atom. The description of these protecting groups is as described above.

[0110] The thiol group protected by a protecting group is preferably a group represented by the formula: -SQ. The description of Q is as described above.

[0111] Compound (I)

[0112] Compound (I) is represented by the following formula (I).

[0113] [Chemical formula 7]

[0114]

[0115] In formula (I), R represents an alkyl group which may have one or more substituents, an aryl group which may have one or more substituents, or an arylalkyl group which may have one or more substituents. The descriptions of the alkyl group, aryl group, arylalkyl group, and one or more substituents are as described above.

[0116] The number of carbon atoms of the alkyl group represented by R is preferably 1 to 10, more preferably 1 to 8, further preferably 1 to 6, further preferably 1 to 5, further preferably 1 to 4, further preferably 1 to 3. Specific examples of the alkyl group represented by R include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl and the like.

[0117] The aryl group represented by R is preferably a phenyl group.

[0118] The number of carbon atoms of the alkyl group contained in the arylalkyl group represented by R is preferably 1 to 10, more preferably 1 to 8, further preferably 1 to 6, further preferably 1 to 5, further preferably 1 to 4, further preferably 1 to 3. Specific examples of the alkyl group contained in the arylalkyl group represented by R are the same as the specific examples of the alkyl group represented by R. The aryl group contained in the arylalkyl group represented by R is preferably a phenyl group. The number of aryl groups contained in the arylalkyl group represented by R is, for example, 1 to 3, preferably 1 or 2, and more preferably 1. Specific examples of the arylalkyl group represented by R include benzyl, phenylethyl, phenylpropyl, phenylbutyl, etc.

[0119] The one or more substituents that the alkyl group, aryl group, and arylalkyl group represented by R may each have may be independently selected from the substituent group α. The one or more substituents are preferably independently selected from a halogen atom, an alkyl group, a haloalkyl group, an alkyloxy group, a haloalkyloxy group, an alkylthio group, and a haloalkylthio group, more preferably selected from a halogen atom, an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, an alkyloxy group having 1 to 3 carbon atoms, and a haloalkyloxy group having 1 to 3 carbon atoms, and even more preferably selected from a halogen atom, an alkyl group having 1 to 3 carbon atoms, and an alkyloxy group having 1 to 3 carbon atoms.

[0120] The five Rs in the formula (I) are the same functional group. Since the five Rs in the formula (I) are the same functional group, the hydroxyl protecting group represented by the formula: -CO-R can be introduced and removed efficiently.

[0121] In one embodiment, all 5 R in formula (I) are methyl. In another embodiment, all 5 R in formula (I) are ethyl. In another embodiment, all 5 R in formula (I) are n-propyl. In another embodiment, all 5 R in formula (I) are isopropyl. In another embodiment, all 5 R in formula (I) are n-butyl. In another embodiment, all 5 R in formula (I) are phenyl.

[0122] 《Compound (II)>>

[0123] Compound (II) is represented by the following formula (II).

[0124] [Chemical formula 8]

[0125]

[0126] In formula (II), X represents a hydrogen atom or an alkali metal atom.

[0127] Examples of the alkali metal atom include a lithium atom (Li), a sodium atom (Na), and a potassium atom (K). In one embodiment, the alkali metal atom is a sodium atom.

[0128] When X is a hydrogen atom, compound (II) is gluconic acid. When X is an alkali metal atom, compound (II) is an alkali metal salt of gluconic acid. In one embodiment, compound (II) is sodium glucuronate.

[0129] 《Acid Anhydride (III)》

[0130] The acid anhydride (III) is represented by the following formula (III).

[0131] [Chemical formula 9]

[0132]

[0133] R in formula (III) has the same meaning as R in formula (I). That is, the two R in formula (III) are the same functional group. In addition, the two R in formula (III) are the same functional group as the five R in formula (I).

[0134] Examples of the acid anhydride (III) include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, and benzoic anhydride.

[0135] When 5 R in formula (I) are methyl groups, 2 R in formula (III) are also methyl groups, and acid anhydride (III) is acetic anhydride. When 5 R in formula (I) are ethyl groups, 2 R in formula (III) are also ethyl groups, and acid anhydride (III) is propionic anhydride. When 5 R in formula (I) are n-propyl groups, 2 R in formula (III) are also n-propyl groups, and acid anhydride (III) is butyric anhydride. When 5 R in formula (I) are isopropyl groups, 2 R in formula (III) are also isopropyl groups, and acid anhydride (III) is isobutyric anhydride. When 5 R in formula (I) are n-butyl groups, 2 R in formula (III) are also n-butyl groups, and acid anhydride (III) is valeric anhydride. When 5 R in formula (I) are phenyl groups, 2 R in formula (III) are also phenyl groups, and acid anhydride (III) is benzoic anhydride.

[0136] 《Acyl chloride (IV)》

[0137] The acid chloride (IV) is represented by the following formula (IV).

[0138] [Chemical formula 10]

[0139]

[0140] R in formula (IV) has the same meaning as R in formula (I). That is, R in formula (IV) is the same functional group as the five Rs in formula (I).

[0141] Examples of the acid chloride (IV) include acetyl chloride, propionyl chloride, butyryl chloride, isobutyryl chloride, valeryl chloride, and benzoyl chloride.

[0142] When five Rs in formula (I) are methyl groups, R in formula (IV) is also methyl, and the acyl chloride (IV) is acetyl chloride. When five Rs in formula (I) are ethyl groups, R in formula (IV) is also ethyl, and the acyl chloride (IV) is propionyl chloride. When five Rs in formula (I) are n-propyl groups, R in formula (IV) is also n-propyl, and the acyl chloride (IV) is butyryl chloride. When five Rs in formula (I) are isopropyl groups, R in formula (IV) is also isopropyl, and the acyl chloride (IV) is isobutyryl chloride. When five Rs in formula (I) are n-butyl groups, R in formula (IV) is also n-butyl, and the acyl chloride (IV) is valeryl chloride. When five Rs in formula (I) are phenyl groups, R in formula (IV) is also phenyl, and the acyl chloride (IV) is benzoyl chloride.

[0143] Acid (V)

[0144] The acid (V) is represented by the following formula (V).

[0145] [Chemical formula 11]

[0146]

[0147] R in formula (V) has the same meaning as R in formula (I). That is, R in formula (V) is the same functional group as the five Rs in formula (I).

[0148] Examples of the acid (V) include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and benzoic acid.

[0149] When 5 R in formula (I) are methyl groups, R in formula (V) is also methyl, and acid (V) is acetic acid. When 5 R in formula (I) are ethyl groups, R in formula (V) is also ethyl, and acid (V) is propionic acid. When 5 R in formula (I) are n-propyl groups, R in formula (V) is also n-propyl, and acid (V) is butyric acid. When 5 R in formula (I) are isopropyl groups, R in formula (V) is also isopropyl, and acid (V) is isobutyric acid. When 5 R in formula (I) are n-butyl groups, R in formula (V) is also n-butyl, and acid (V) is valeric acid. When 5 R in formula (I) are phenyl groups, R in formula (V) is also phenyl, and acid (V) is benzoic acid.

[0150] 《Method for producing compound (I)》

[0151] The method of the present invention relates to the following method, which is a method for producing compound (I), the method comprising the following steps: adding compound (II), acid anhydride (III), acid chloride (IV) and zinc chloride (ZnCl2) to a reaction container, and mixing compound (II), acid anhydride (III), acid chloride (IV) and zinc chloride.

[0152] According to the method of the present invention, compound (I) can be obtained from compound (II) in a short process and at a high yield. The yield of compound (I) is, for example, 60% or more, preferably 70% or more, and more preferably 80% or more.

[0153] The shape, material, etc. of the reaction container are not particularly limited as long as the above-mentioned steps can be carried out.

[0154] The mechanism by which compound (I) is formed by mixing compound (II), acid anhydride (III), acid chloride derivative (IV) and zinc chloride is as follows.

[0155] (A) By reacting -OH of compound (II) with acid anhydride (III), -OH of compound (II) is converted into -O-CO-R, and acid (V) is generated.

[0156] (B) Zinc chloride acts as a promoter that promotes the reaction in (A). Specifically, zinc chloride acts as a Lewis acid and coordinates to the oxygen atom of the carbonyl group (-CO-) of the acid anhydride (III) to promote the reaction in (A). When compound (II) is an alkali metal salt of gluconic acid (i.e., when X in formula (II) is an alkali metal atom), zinc chloride also acts as a dealkalizing agent that removes alkali metal from the alkali metal salt of gluconic acid.

[0157] (C) Acid (V) produced in (A) reacts with acid chloride (IV) to produce acid anhydride (III) and hydrogen chloride (HCl). The produced acid anhydride (III) is used in the reaction in (A). The produced hydrogen chloride acts as a Bronsted acid and coordinates to the oxygen atom of the carbonyl group (-CO-) of the acid anhydride (III) in the same manner as zinc chloride, thereby promoting the reaction in (A).

[0158] From the viewpoint of further improving the yield of compound (I), it is preferred that in the above step, acid (V) is further added to the reaction vessel to mix compound (II), acid anhydride (III), acid chloride (IV), zinc chloride and acid (V).

[0159] The mechanism by which the yield of compound (I) is improved by mixing compound (II), acid anhydride (III), acid chloride derivative (IV), zinc chloride and acid (V) is as follows.

[0160] When the acid (V) is used separately from the acid (V) generated by the reaction in (A), the generation of the acid anhydride (III) and hydrogen chloride in (C) can be promoted. This can promote the reaction in (A) and improve the yield of the compound (I).

[0161] The compound (II), the acid anhydride (III), the acid chloride derivative (IV), zinc chloride and the acid (V) may be commercially available products or may be produced according to a conventional method.

[0162] The mixing in the above step is carried out in a reaction vessel. The temperature when carrying out the mixing in the above step is, for example, -10 to 70°C, preferably 0 to 60°C, and more preferably 10 to 50°C. The time for carrying out the mixing in the above step is, for example, 1 to 48 hours, preferably 5 to 36 hours, and more preferably 5 to 24 hours. The mixing in the above step can be carried out, for example, under an inert atmosphere (for example, under an argon atmosphere or a nitrogen atmosphere). The mixing in the above step can be carried out, for example, by stirring the mixture obtained by adding compound (II), acid anhydride (III), acid chloride derivative (IV), zinc chloride and, if necessary, acid (V) to a reaction vessel.

[0163] When compound (II), acid anhydride (III), acyl chloride (IV), zinc chloride and acid (V) used as appropriate are added to a reaction vessel, the order of addition is not particularly limited. For example, the acyl chloride derivative (IV) can be added after compound (II) is added to a reaction vessel containing acid anhydride (III), zinc chloride and acid (V) used as appropriate. In this example, the order in which acid anhydride (III), zinc chloride and acid (V) used as appropriate are added to the reaction vessel is not particularly limited. In this example, the acyl chloride derivative (IV) can be added, for example, by dropwise addition.

[0164] The amount of the acid anhydride (III) added is, for example, 5 to 20 mol, preferably 5 to 15 mol, and more preferably 2 to 5 mol, per 1 mol of the compound (II).

[0165] The amount of the acid chloride derivative (IV) added is, for example, 0.01 to 10 mol, preferably 0.05 to 7 mol, and more preferably 0.05 to 5 mol, based on 1 mol of the compound (II).

[0166] The amount of zinc chloride added is, for example, 0.01 to 2 mol, preferably 0.05 to 0.7 mol, and more preferably 0.05 to 0.5 mol, based on 1 mol of compound (II).

[0167] The amount of the acid (V) added is, for example, 0 to 10 mol, preferably 0 to 1.5 mol, and more preferably 0 to 1.0 mol, based on 1 mol of the compound (II).

[0168] The mixing in the above-mentioned process is preferably carried out in the absence of a solvent, but can also be carried out in a solvent. As a solvent, for example, an organic solvent can be used. One organic solvent can be used alone, or a mixed solvent of two or more organic solvents can be used. As an organic solvent, for example, nitrile solvents such as acetonitrile and propionitrile; ether solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, cyclopentyl methyl ether, dibutyl ether, 1,4-dioxane, tert-butyl methyl ether, diisopropyl ether, dimethoxyethane, diethylene glycol dimethyl ether; ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate; halogenated hydrocarbon solvents such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, chlorobenzene; aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as hexane and heptane, etc. Among them, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, tert-butyl methyl ether, cyclopentyl methyl ether, dimethoxyethane, diglyme, dichloromethane, toluene, xylene, hexane, heptane and the like are preferred.

[0169] The amount of the solvent used is, for example, 0 to 100 mL, preferably 0 to 5 mL, and more preferably 0 mL (ie, no solvent), based on 1 g of compound (II).

[0170] Compound (I) can be isolated from the reaction mixture according to a conventional method.

[0171] For example, after the mixing in the above step, compound (I) is extracted from the reaction mixture to obtain an extract (crude product) containing compound (I), and the obtained extract is subjected to a purification treatment such as solidification treatment and silica gel column chromatography treatment, thereby isolating compound (I).

[0172] The above steps can obtain a highly pure compound (I), and the compound (I) can be easily solidified. Therefore, by combining the above steps with a solidification treatment, the compound (I) can be obtained in a solid form, and can also be obtained in a crystalline form.

[0173] When compound (I) is extracted from the reaction mixture, an organic solvent is preferably used as an extraction solvent. One organic solvent can be used alone, or two or more organic solvents can be used in combination. The organic solvent used to extract compound (I) from the reaction mixture is preferably ethyl acetate, methyl acetate, dichloromethane, chloroform, methyl tert-butyl ether, hexane, toluene, xylene, 1,4-dioxane, ether, dibutyl ether, cyclopentyl methyl ether or a mixed solvent thereof.

[0174] Extraction of compound (I) from the reaction mixture can be carried out, for example, by the following method.

[0175] First, a quenching solution (e.g., water, aqueous hydrochloric acid solution, sodium bicarbonate aqueous solution, etc.) and an organic solvent used as needed are added to the reaction mixture to stop the reaction. The reaction mixture to which the quenching solution and the organic solvent used as needed are added is stirred to separate it into an aqueous layer and an organic layer (hereinafter referred to as "organic layer (A)". After the organic layer (A) is taken out, an organic solvent can also be added to the aqueous layer to separate it into an aqueous layer and an organic layer (hereinafter referred to as "organic layer (B)"). The organic layer (B) is taken out and combined with the previously taken out organic layer (A) to obtain a total organic layer. Then, a residue containing compound (I) is obtained from the organic layer (A) or the total organic layer. For example, the organic layer (A) or the total organic layer can be washed with a washing solution (e.g., water, aqueous hydrochloric acid solution, sodium bicarbonate aqueous solution, brine (brine) solution, etc.) as needed, and after drying with sodium sulfate, filtering, reduced pressure drying, etc. are implemented to obtain a residue containing compound (I). The residue containing compound (I) thus obtained is an example of an extract (crude product) containing compound (I).

[0176] As the organic solvent added to the reaction mixture or the water layer, one organic solvent may be used alone, or two or more organic solvents may be used in combination. The organic solvent added to the reaction mixture or the water layer is preferably ethyl acetate, methyl acetate, dichloromethane, chloroform, methyl tert-butyl ether, hexane, toluene, xylene, 1,4-dioxane, diethyl ether, dibutyl ether, cyclopentyl methyl ether, or a mixed solvent thereof.

[0177] The solidification treatment of the extract is preferably carried out using two solvents. As the two solvents, mutually soluble (i.e. miscible) solvents are selected. Among the two solvents, one solvent is a solvent with a large solubility for compound (I) (hereinafter referred to as the "first solvent"), and the other solvent is a solvent with a small solubility for compound (I) (hereinafter referred to as the "second solvent").

[0178] Examples of the first solvent include methyl acetate, ethyl acetate, dichloromethane, chloroform, methyl tert-butyl ether, etc. The first solvent is preferably ethyl acetate.

[0179] Examples of the second solvent include pentane, hexane, and heptane. The second solvent is preferably hexane.

[0180] The combination of the two solvents is preferably ethyl acetate / hexane.

[0181] The solidification treatment of the extract can be carried out by sequentially adding the first solvent and the second solvent to the extract, stirring and then letting it stand, or by adding a mixture of the first solvent and the second solvent to the extract, stirring and then letting it stand. The volume ratio of the amount of the first solvent used to the amount of the second solvent used (the amount of the first solvent used / the amount of the second solvent used) is, for example, 1 / 1 to 1 / 8, preferably 1 / 2 to 1 / 7, and more preferably 1 / 3 to 1 / 6. Relative to 1g of the extract, the total amount of the first solvent and the second solvent used is, for example, 1 to 200mL, preferably 2 to 100mL, and more preferably 3 to 50mL. The stirring time is, for example, 1 to 48 hours, preferably 1 to 36 hours, and more preferably 1 to 24 hours. The solidification treatment can be carried out at room temperature, for example. Room temperature is, for example, a temperature of 15 to 35°C (especially 25°C).

[0182] The solid of compound (I) produced by the solidification treatment can be separated by a solid-liquid separation method. Examples of the solid-liquid separation method include filtration and decantation.

[0183] The solid of the separated compound (I) can be washed with a washing liquid. As the washing liquid, an organic solvent is preferably used. One organic solvent can be used alone, or two or more organic solvents can be used in combination. As the washing liquid, for example, pentane, hexane, heptane, diisopropyl ether, methyl tert-butyl ether, etc. can be mentioned.

[0184] The structure of compound (I) can be confirmed by, for example, nuclear magnetic resonance (NMR) spectral analysis.

[0185] Example

[0186] <Example 1>

[0187] According to the following reaction formula, (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) is produced. In the following reaction formula, "Ac" represents an acetyl group.

[0188] [Chemical formula 12]

[0189]

[0190] To freshly prepared zinc chloride (ZnCl2) (156 mg, 1.146 mmol), acetic anhydride (Ac2O) (2.67 mL, 27.50 mmol) and acetic acid (AcOH) (0.5 mL, 2.75 mmol) were added at 0°C, respectively. Sodium gluconate (1) (500 mg, 2.292 mmol) was added to the reaction mixture at 0°C. The reaction mixture was stirred for 5 minutes. Acetyl chloride (AcCl) (1 mL, 13.75 mmol) was added dropwise to the reaction mixture, and then the mixture was slowly returned to room temperature and stirred at room temperature for 18 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction mixture was ice-cooled to 0°C, the reaction was quenched with cold water (10 mL), extracted with ethyl acetate (3×15 mL), and the organic layers were combined. The combined organic layers were washed with aqueous sodium bicarbonate solution (5 mL) and washed with brine (3×15 mL). The organic layer was dried over sodium sulfate, concentrated by vacuum suction, co-evaporated with toluene (3×10 mL), and maintained under high vacuum for 2 hours to obtain a sticky crude solid. Ethyl acetate / hexane (total amount: 20 mL, proportion of ethyl acetate: 5 volume %) was added to the obtained sticky crude solid and stirred for 12 hours. The obtained solid was filtered and dried by vacuum suction to obtain (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) (786 mg, yield: 84%) as a white solid.

[0191] The analysis results of the obtained (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) are shown below.

[0192] IR: 3550, 2900, 1749, 1219cm -1 ;

[0193] 1 H NMR (500MHz, CDCl3, 25°C): δ8.36 (bs, 1H), 5.63 (t, J=4.1Hz, 1H), 5.51 (t, J=5.5Hz, 1H), 5.31 (d, J=3.2Hz, 1H), 5.08 (dd , J=9.9, 5.2Hz, 1H), 4.31 (dd, J=12.2, 3.7Hz, 1H), 4.14 (dd, J=12.2, 5.4Hz, 1H), 2.20 (s, 3H), 2.09 (s, 9H), 2.06 (s, 3H).

[0194] 13C NMR (126MHz, CDCl3, 25℃): δ170.78, 170.72, 170.01, 169.94, 169.86, 70.19, 69.37, 68.65, 68.61, 61.56, 20.78, 20.73, 20.64, 20.45, 20.39.

[0195] <Example 2>

[0196] According to the following reaction formula, (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) is produced. In the following reaction formula, "Ac" represents an acetyl group.

[0197] [Chemical formula 13]

[0198]

[0199] Acetic anhydride (Ac2O) (5.3 mL, 55.00 mmol) was added to freshly prepared zinc chloride (ZnCl2) (312 mg, 2.292 mmol) at 0°C. Sodium gluconate (1) (1 g, 4.584 mmol) was added to the reaction mixture at 0°C. The reaction mixture was stirred for 5 minutes. Acetyl chloride (AcCl) (2.0 mL, 27.500 mmol) was added dropwise to the reaction mixture, and then the mixture was slowly returned to room temperature and stirred at room temperature for 18 hours. The reaction was monitored by TLC. After the reaction was completed, the reaction mixture was cooled to 0°C, quenched with ice-cold water (20 mL), extracted with ethyl acetate (3×20 mL), and the organic layers were combined. The combined organic layers were washed with aqueous sodium bicarbonate solution (5 mL) and washed with brine (3×20 mL). The organic layer was dried over sodium sulfate, concentrated by vacuum suction, co-evaporated with toluene (3×15 mL), and maintained under high vacuum for 2 hours to obtain a sticky crude solid. Ethyl acetate / hexane (total amount: 20 mL, proportion of ethyl acetate: 5 volume %) was added to the obtained crude solid and stirred for 8 hours. The obtained solid was filtered and dried by vacuum suction to obtain (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) (1.49 g, yield: 83%) as a white solid.

[0200] The analysis results of the obtained (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) are shown below.

[0201] 1H NMR (500MHz, CDCl3, 25°C): δ8.36 (bs, 1H), 5.63 (t, J=4.1Hz, 1H), 5.51 (t, J=5.5Hz, 1H), 5.29 (d, J=3.2Hz, 1H), 5.08 (dd , J=9.9, 5.2Hz, 1H), 4.31 (dd, J=12.2, 3.7Hz, 1H), 4.14 (dd, J=12.2, 5.4Hz, 1H), 2.20 (s, 3H), 2.09 (s, 9H), 2.06 (s, 3H).

[0202] 13 C NMR (126MHz, CDCl3, 25℃): δ170.80, 170.72, 170.03, 170.01, 169.95, 169. 87, 70.18, 69.37, 68.65, 68.60, 61.56, 20.78, 20.73, 20.64, 20.44, 20.39.

[0203] <Reference Example 1>

[0204] Reference Example 1 is an additional experiment of U.S. Patent No. 4,567,285 (issued on January 28, 1986). In Reference Example 1, (2R,3S,4R,5R)-2,3,4,6-tetraacetoxy-5-hydroxyhexanoic acid (4) was produced according to the following reaction formula. In the following reaction formula, "Ac" represents an acetyl group.

[0205] [Chemical formula 14]

[0206]

[0207] Zinc chloride (ZnCl2) (4 g, 0.0029 mol, 0.52 equiv) was slowly added to a suspension of d-(+)-glucono-1,5-lactone (3) (10 g, 0.056 mol, 1.00 equiv) and acetic anhydride (Ac2O) (50.0 mL, 0.531 mol, 9.46 equiv) at 20-25°C over 5 minutes. The reaction mixture was then stirred at 20-25°C for 16 hours. The progress of the reaction was monitored by TLC. Water (300 mL, 30 times the volume) was added to quench the reaction, and the reaction mixture was stirred for 16 hours. The formation of white crystals was observed in the reaction mass. The generated crystals were filtered and washed with water (25 mL×2). The wet compound was dried at 40 to 45° C. for 4 hours by vacuum suction to obtain 13.0 g (yield: 64%) of (2R,3S,4R,5R)-2,3,4,6-tetraacetoxy-5-hydroxyhexanoic acid (4) as a white solid.

[0208] The analysis results of the obtained (2R,3S,4R,5R)-2,3,4,6-tetraacetoxy-5-hydroxyhexanoic acid (4) are shown below.

[0209] 1 H NMR (500MHz, DMSO-d6, 30℃) δ (ppm): 5.65-5.55 (m, 2H), 5.15-5.05 (m, 2H), 4.00-3 .88(m, 2H), 3.76(dt, J=11.8, 5.8Hz, 1H), 2.09(s, 3H), 2.02(s, 3H), 2.00(s, 6H).

[0210] <Reference Example 2>

[0211] Reference Example 2 is an additional experiment of U.S. Patent No. 4,567,285 (issued on January 28, 1986). In Reference Example 2, (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) was produced according to the following reaction formula. In the following reaction formula, "Ac" represents an acetyl group.

[0212] [Chemical formula 15]

[0213]

[0214] To a solution of (2R,3S,4R,5R)-2,3,4,6-tetraacetoxy-5-hydroxyhexanoic acid (4) (5 g, 13.72 mmol, 1.00 equiv) and acetic anhydride (Ac2O) (20 mL, 4 times the volume) prepared in Reference Example 1, zinc chloride (ZnCl2) (1.80 g, 13.17 mol, 0.96 equiv) was slowly added at 20-25°C. Then, the reaction mixture was stirred at 20-25°C for 16 hours. The progress of the reaction was monitored by TLC. The reaction was quenched with water (50 mL). The reaction mass was extracted with ethyl acetate (50 mL×2), and the organic layer was washed with water (50 mL), saturated aqueous sodium bicarbonate solution (50 mL) and brine (50 mL). The organic layer was dried with sodium sulfate and filtered. The solvent was removed by vacuum suction to obtain a crude compound. The crude compound was purified by grinding in n-hexane / ethyl acetate (50 mL, ratio 80 / 20). The obtained crystals were filtered and washed with hexane (25 mL×2). The wet compound was dried at 40-45° C. by vacuum suction for 4 hours to obtain 5.0 g (yield 89%) of (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) as a white solid.

[0215] The analysis results of the obtained (2R,3S,4R,5R)-2,3,4,5,6-pentaacetylgluconic acid (2) are shown below.

[0216] 1 H NMR (500MHz, DMSO-d6, 30℃) δ (ppm): 5.53 (dd, J=5.4, 3.4Hz, 1H), 5.36 (t, J=5.6Hz, 1H), 5.16 (d, J=3.4Hz, 1H), 4.94 (td, J=6.0, 3.8Hz, 1H), 4.24 (dd, J=12.2, 3.7Hz, 1H), 4.08 (dd, J=12.2, 6.2Hz, 1H), 2.07 (s, 3H), 2.02 (s, 3H), 1.98 (s, 3H), 1.97 (s, 3H), 1.95 (s, 3H), 1.87 (s, 1H).

Claims

1. A method for producing a compound (I) represented by the following formula (I), the method comprising the following steps: Add a compound (II) represented by the following formula (II), an acid anhydride (III) represented by the following formula (III), an acid chloride (IV) represented by the following formula (IV), and zinc chloride to a reaction container, and mix the compound (II), the acid anhydride (III), the acid chloride (IV), and the zinc chloride. [Chemical formula 1] In formula (I), R represents an alkyl group which may have one or more substituents, an aryl group which may have one or more substituents, or an arylalkyl group which may have one or more substituents; [Chemical formula 2] In formula (II), X represents a hydrogen atom or an alkali metal atom; [Chemical formula 3] In formula (III), R has the same meaning as above; [Chemical formula 4] In formula (IV), R has the same meaning as above.

2. The method of claim 1, wherein: In the step, an acid (V) represented by the following formula (V) is further added to the reaction container, and the compound (II), the acid anhydride (III), the acid chloride (IV), the zinc chloride and the acid (V) are mixed. [Chemical formula 5] In formula (V), R has the same meaning as above.

Images