Method for producing hydroxycinnamoyl-quinic acids

Abstract

Provided is a method for effectively producing hydroxycinnamoyl-quinic acids.　Disclosed is a method for producing tri(hydroxycinnamoyl) quinic acid and / or tetra(hydroxycinnamoyl) quinic acid, the method including: a first step for protecting the phenolic hydroxy groups of hydroxycinnamic acid with silyl protecting groups; after the first step, a second step for forming ester bonds between carboxy groups of hydroxycinnamic acid and hydroxy groups of quinic acid; and after the second step, a third step for removing the silyl protecting groups from the phenolic hydroxy groups protected by the silyl protecting groups.

Description

Method for producing hydroxycinnamoylquinic acids

[0001] The present disclosure relates to a method for producing hydroxycinnamoyl quinic acids.

[0002] Hydroxycinnamoylquinic acids, which are ester compounds of hydroxycinnamic acid and quinic acid, are known to have useful physiological functions. For example, tricaffeoylquinic acid, which is composed of three molecules of caffeic acid and one molecule of quinic acid bonded by an ester bond, is known to be contained in sweet potato leaves, propolis, goldenrod, and holly daisy, and is known to have spatial learning and memory improving effects, neurogenesis effects (Non-Patent Document 1), neuroprotective effects against amyloid beta-induced cell death (Non-Patent Document 2), hair growth promoting effects (Non-Patent Document 3), etc. In addition, tetracaffeoylquinic acid, which is composed of four molecules of caffeic acid and one molecule of quinic acid bonded by an ester bond, is known to be contained in Pulchea symphytifolia, holly daisy, etc., and is known to have growth inhibitory effects against Escherichia coli and Bacillus subtilis (Non-Patent Document 4), collagenase inhibitory effects (Non-Patent Document 5), etc. In addition, triferuloylquinic acid, which is composed of three molecules of ferulic acid and one molecule of quinic acid, is known to have a neurogenesis promoting effect (Non-Patent Document 6).

[0003] Hydroxycinnamoylquinic acids can be produced by isolating and purifying them from natural organisms, but for supplying them to the market on an industrial scale, it is desirable to produce them more efficiently using organic synthesis techniques.

[0004] For example, a chemical synthesis method for tricaffeoylquinic acid has been reported, which involves forming an ester bond between caffeic acid, the phenolic hydroxy group of which is protected with an acetyl group (Non-Patent Document 7) or a methoxycarbonyl group (Patent Document 1), and quinic acid.

[0005] JP 2017-145215 A

[0006] Aging, 2019, Vol. 17, p. 401; Cytotechnology, 2011, Vol. 63, p. 191; Cells, 2022, Vol. 11, p. 2093; Planta Med., 2019, Vol. 60, p. 360; Phytother. Res., 2008, Vol. 22, p. 26490; ACS Chem. Neurosci., 2024, Vol. 15, p. 3713; Chem. Pharm. Bull., 2011, Vol. 59, p. 502

[0007] An objective of the present disclosure is to provide a method for effectively producing hydroxycinnamoylquinic acids.

[0008] The present inventors have discovered that tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid can be effectively produced by using a hydroxycinnamic acid in which the phenolic hydroxy group is protected with a silyl protecting group, and have completed the present invention. Specifically, the present disclosure provides, for example, the following method: [1] A method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, comprising: a first step of protecting the phenolic hydroxy group of the hydroxycinnamic acid with a silyl protecting group; a second step, after the first step, of forming an ester bond between a carboxy group of the hydroxycinnamic acid and a hydroxy group of quinic acid; and a third step, after the second step, of removing the silyl protecting group from the phenolic hydroxy group protected with the silyl protecting group.

[0009] According to the present disclosure, hydroxycinnamoylquinic acids can be effectively produced.

[0010] Fig. 1 shows a synthesis scheme for tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to Example 1. Fig. 2 shows a synthesis scheme for tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to Example 2. Fig. 3 shows a synthesis scheme for tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to Example 3. Fig. 4 shows a synthesis scheme for tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to Example 4. Fig. 5 shows a synthesis scheme for tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to Example 5.

[0011] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, when multiple upper and lower limit values ​​are described for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limit values ​​of a numerical range described in this disclosure are numerical values ​​within that numerical range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0012] In one embodiment, a method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid is disclosed, comprising: a first step of protecting a phenolic hydroxy group of a hydroxycinnamic acid with a silyl protecting group; a second step of forming an ester bond between a carboxy group of the hydroxycinnamic acid and a hydroxy group of quinic acid after the first step; and a third step of removing the silyl protecting group from the phenolic hydroxy group protected with the silyl protecting group after the second step. This method enables tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid to be produced in a small number of steps and / or in a high yield.

[0013] <Tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid> Unless otherwise specified, tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid refer to 3,4,5-tri-(hydroxycinnamoyl)quinic acid and 1,3,4,5-tetra-(hydroxycinnamoyl)quinic acid, respectively.

[0014] When the hydroxycinnamic acid is caffeic acid, tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid are tricaffeoylquinic acid and tetracaffeoylquinic acid, respectively, and unless otherwise specified, these refer to 3,4,5-tri-caffeoylquinic acid and 1,3,4,5-tetra-caffeoylquinic acid. When the hydroxycinnamic acid is ferulic acid, tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid are triferuloylquinic acid and tetraferuloylquinic acid, respectively, and unless otherwise specified, these refer to 3,4,5-tri-feruloylquinic acid and 1,3,4,5-tetra-feruloylquinic acid.

[0015] Hydroxycinnamic acids are hydroxy derivatives of cinnamic acid. Non-limiting examples of hydroxycinnamic acids include caffeic acid, ferulic acid, coumaric acid, and sinapic acid.

[0016] Unless otherwise specified, hydroxycinnamic acid may be hydroxycinnamic acid that is not protected by a protecting group, or may be hydroxycinnamic acid whose side chain is protected by a protecting group.For example, in the present disclosure, when simply referred to as "caffeic acid," the caffeic acid may be caffeic acid whose phenolic hydroxy group is protected by a protecting group (e.g., a silyl protecting group or a methyl group).In addition, caffeic acid whose hydroxy group at the 3-position of the phenolic group is protected by a methyl group is ferulic acid.

[0017] <Quinic Acid> Unless otherwise specified, "quinic acid" may be quinic acid that is not protected with a protecting group, or quinic acid whose side chain is protected with a protecting group. For example, when simply referring to "quinic acid" in the present disclosure, the quinic acid may be quinic acid whose carboxy group is protected with a protecting group (e.g., methyl group) (methyl quinate).

[0018] <First Step> In the first step, the phenolic hydroxy group of the hydroxycinnamic acid is protected with a silyl protecting group.

[0019] (Silyl Protecting Group) In the present disclosure, the silyl protecting group refers to a protecting group that contains silicon and can effectively protect a phenolic hydroxy group by forming a silyl ether bond between the silicon and the phenolic hydroxy group. In the present disclosure, any silyl protecting group can be used as long as the effects of the present invention can be obtained. The silyl protecting group is preferably -SiR ３ wherein R is independently C １ -C ６ It is a hydrocarbon group. １ -C ６ The hydrocarbon group is C １ -C ６ Alkyl group, C ２ -C ６ Alkenyl group, C ２ -C ６ Alkynyl group, C ３ -C ６ Cycloalkyl group, C ３ -C ６ Cycloalkenyl group, C３ -C ６ Cycloalkynyl group, C ５ -C ６ It may be an aryl group, or a hydrocarbon group in which some atoms or functional groups have been substituted with other atoms or functional groups. １ -C ６ The alkyl group is preferably C ２ -C ５ alkyl group, more preferably C ３ -C ４ It is an alkyl group. ５ -C ６ Aryl is preferably C ６ An aryl (phenyl) group. ３ The three R's included in the formula (I) may all be different, or two of the three R's may be the same, or three of the three R's may be the same, but preferably two or three of the three R's are the same. ３ When two or three of the three R's contained in the formula are the same, the Si atom does not form an asymmetric center, and therefore the silyl protecting group is easy to handle since it does not include diastereomers. ３ , -CH ２ CH ３ , -CH ２ CH ２ CH ３ , -CH(CH ３ ) ２ , -CH ２ CH ２ CH ２ CH ３ , -C(CH ３ ) ３ , -CH ２ CH (CH ３ ) ２ , -CH(CH ３ ) (CH ２ CH ３ ), and -C ６ H ５Non-limiting examples of silyl protecting groups include trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), tert-butyldimethylsilyl (TBS), diethylisopropylsilyl (DEIPS), and tert-butyldiphenylsilyl (TBDPS). When a bulky silyl protecting group is used, protection and / or deprotection of a phenolic hydroxy group tends to be more efficient. Non-limiting examples of such bulky silyl protecting groups include triisopropylsilyl (TIPS), tert-butyldimethylsilyl (TBS), diethylisopropylsilyl (DEIPS), and tert-butyldiphenylsilyl (TBDPS).

[0020] (Introduction of Silyl Protecting Group) A silyl protecting group is introduced into the phenolic hydroxy group of a hydroxycinnamic acid by reacting the hydroxycinnamic acid with a silyl protecting group introducing reagent known to those skilled in the art. The silyl protecting group introducing reagent is preferably a compound in which the above-mentioned silyl protecting group is bonded to a halogen. The halogen is preferably chlorine, bromine, or iodine, and more preferably chlorine. For example, when the phenolic hydroxy group is protected with a triisopropylsilyl (TIPS) group, triisopropylsilyl (TIPS) chloride is preferably used as the silyl protecting group introducing reagent. The molar ratio of the hydroxycinnamic acid to the silyl protecting group introducing reagent in this reaction system can be any ratio as long as the effects of the present invention are achieved. For example, the range may be preferably 10:1 to 1:10, more preferably 3:1 to 1:3. When the silyl protecting group introducing reagent is a compound in which the silyl protecting group is bound to a halogen, a compound that bonds with the halogen released from the silyl protecting group is preferably further added to the reaction system. Suitable examples of such a compound include nitrogen-containing compounds such as imidazole, 4-dimethylaminopyridine (DMAP), dimethylformamide, triethylamine, pyridine, and lutidine, as well as iodine and sodium hydride. The compound is preferably added to the reaction system in an amount greater than the amount of the silyl protecting group introducing reagent (for example, a molar ratio of 1.5 to 10 times the amount of the silyl protecting group introducing reagent).

[0021] The reaction of hydroxycinnamic acid with a silyl protecting group introducing reagent can be carried out in any solvent as long as the effects of the present invention are achieved, including, but not limited to, dimethylformamide (DMF).

[0022] The yield of the reaction in which a silyl protecting group is introduced into the phenolic hydroxy group of a hydroxycinnamic acid using a silyl protecting group introducing reagent is preferably 80% or more, more preferably 85% or more.

[0023] The temperature for the reaction between the hydroxycinnamic acid and the silyl protecting group introducing reagent is appropriately set within a range in which the effects of the present invention can be obtained. The temperature can be appropriately adjusted so as to obtain the above-mentioned preferred yield. The temperature may be, for example, 20 to 30°C, or may be room temperature.

[0024] The reaction time between the hydroxycinnamic acid and the silyl protecting group introducing reagent is appropriately set within a range in which the effects of the present invention can be obtained. The reaction time can be appropriately adjusted so as to obtain the preferred yield described above. The reaction time may be, for example, 2 to 24 hours, or 6 to 18 hours.

[0025] The reaction between hydroxycinnamic acid and a silyl protecting group introducing reagent can be terminated by adding a reaction terminating reagent. Any reagent can be used as the reaction terminating reagent as long as the effects of the present invention can be obtained, but it is preferable to use an excess amount of water relative to the reaction reagent.

[0026] After the reaction of hydroxycinnamic acid with a silyl-protecting group-introducing reagent, the hydroxycinnamic acid in which the phenolic hydroxy group is protected with a silyl-protecting group can be purified by a known purification method, non-limiting examples of which include extraction with ethyl acetate, n-hexane, etc., and chromatography using silica gel, activated carbon, Celite, etc. as a carrier.

[0027] <Second Step> In the second step, an ester bond is formed between the carboxy group of the hydroxycinnamic acid and the hydroxy group of the quinic acid. That is, by carrying out the second step of forming an ester bond between the carboxy group of the hydroxycinnamic acid, in which the phenolic hydroxy group is protected with a silyl protecting group, and the hydroxy group of the quinic acid, tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, in which the phenolic hydroxy group is protected with a silyl protecting group, is produced. The quinic acid used in the second step is preferably quinic acid in which the carboxy group is protected with a protecting group. The protecting group is preferably a methyl group, a benzyl group, or a 4-methoxybenzyl group. The quinic acid used in the second step is preferably quinic acid in which the carboxy group is protected with a methyl group (methyl quinate). Quinic acid in which the carboxy group is protected with a methyl group can be prepared by a known method. It can also be prepared in the additional step of protecting the carboxy group of quinic acid with a methyl group, as described below.

[0028] The second step can be carried out, for example, as follows. However, the method is not limited thereto. First, the carboxy group of a hydroxycinnamic acid in which the phenolic hydroxy group is protected with a silyl protecting group is halogenated with a halogenating reagent such as oxalyl chloride or thionyl chloride in an appropriate solvent (e.g., 1,2-dichloroethane (EDC), toluene, benzene, tetrahydrofuran, dimethylformamide, etc.) to produce a halogenated caffeic acid. The halogenation yield is preferably 95% or more, more preferably 98% or more, or may be quantitative. Next, the halogenated hydroxycinnamic acid and quinic acid are mixed and reacted in an appropriate solvent (e.g., 1,2-dichloroethane (EDC), dichloromethane, tetrahydrofuran, 1,4-dioxane, toluene, benzene, dimethylformamide, or a combination thereof) to form an ester bond between the carboxy group of the hydroxycinnamic acid and the hydroxy group of the quinic acid.

[0029] The molar ratio of the halogenated hydroxycinnamic acid to quinic acid may be any range as long as the effects of the present invention are achieved. The molar ratio of the halogenated hydroxycinnamic acid to quinic acid can be adjusted according to the desired molar ratio of tri(hydroxycinnamoyl)quinic acid to tetra(hydroxycinnamoyl)quinic acid to be produced. That is, by lowering the ratio of halogenated hydroxycinnamic acid to quinic acid, the ratio of tri(hydroxycinnamoyl)quinic acid to tetra(hydroxycinnamoyl)quinic acid can be increased, and by increasing the ratio of halogenated hydroxycinnamic acid to quinic acid, the ratio of tetra(hydroxycinnamoyl)quinic acid to tri(hydroxycinnamoyl)quinic acid can be increased. The molar ratio of the halogenated hydroxycinnamic acid to quinic acid may preferably be 10:1 to 2:1, more preferably 3.5:1 to 2.5:1.

[0030] The ester bond formation reaction produces tri(hydroxycinnamoyl)quinic acid, tetra(hydroxycinnamoyl)quinic acid, or a mixture thereof, in which the phenolic hydroxy group derived from the hydroxycinnamic acid is protected with a silyl protecting group. In the tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid, the carboxy group derived from the quinic acid is preferably protected with a protecting group (e.g., a methyl group). For example, when the hydroxycinnamic acid is caffeic acid, the caffeic acid is 3,4-di-O-triisopropylsilyl caffeic acid, and the quinic acid is a quinic acid in which the carboxy group is protected with a methyl group, the ester bond formation reaction can produce methyl 3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate, methyl 1,3,4,5-tetrakis(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate, or a mixture thereof.

[0031] The second step preferably comprises forming an ester bond between a carboxy group of the hydroxycinnamic acid and a hydroxy group of the quinic acid in a solvent containing one or more bases. Any bases may be used as the solvent as long as the effects of the present invention can be obtained. Non-limiting examples of the bases include imidazole, 4-dimethylaminopyridine (DMAP), dimethylformamide, triethylamine, pyridine, lutidine, and diisopropylethylamine (iPr). ２ EtN), and combinations thereof.

[0032] The one or more bases preferably include a base that forms an acyl intermediate in the esterification reaction and / or a base that traps hydrochloric acid, a by-product of the esterification reaction. By including such a base, the esterification reaction can be effectively promoted. The base that forms the acyl intermediate may be any base within the range in which the effects of the present invention can be obtained, but a base with high nucleophilicity is preferred, and a non-limiting example of such a base is 4-dimethylaminopyridine (DMAP). The amount of such a base may be a catalytic amount. The base that traps hydrochloric acid may be any base within the range in which the effects of the present invention can be obtained, but a non-limiting example of such a base is pyridine, diisopropylethylamine (iPr ２ The amount of the base can be appropriately set depending on the amount of the base to be trapped, and may be, for example, 0.1 to 10 times the molar ratio of the amount of the silyl protecting group introducing reagent.

[0033] Any solvent can be used as long as the effects of the present invention can be obtained. Non-limiting examples of the solvent include 1,2-dichloroethane (EDC), dichloromethane, tetrahydrofuran, 1,4-dioxane, toluene, benzene, dimethylformamide, and combinations thereof.

[0034] In the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, when it is desired to synthesize tri(hydroxycinnamoyl)quinic acid with higher priority, it is preferable that the solvent contains a base with a lower pKa and / or has a lower dielectric constant. For example, it is preferable that the solvent contains a base with a pKa of 6 or less and / or has a dielectric constant of 6 or less. Without being bound by theory, a base with a lower pKa has a lower ability to trap hydrochloric acid, a by-product of the esterification reaction, and therefore tends to maintain a lower pKa of the reaction system. Therefore, it is believed that when the reaction system contains a base with a lower pKa, the formation of four or more ester bonds is suppressed. It is also believed that the use of a solvent with a dielectric constant of 6 or less suppresses ionic reactions, thereby suppressing the formation of four or more ester bonds.

[0035] Any base having a pKa of 6 or less can be used as long as the effects of the present invention can be obtained, and non-limiting examples thereof include pyridine (pKa = 5.2). Any solvent having a dielectric constant of 6 or less can be used as long as the effects of the present invention can be obtained, and non-limiting examples thereof include tetrahydrofuran (dielectric constant 5.6) and 1,4-dioxane (dielectric constant 2.2).

[0036] In the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, if it is desired to synthesize tetra(hydroxycinnamoyl)quinic acid more efficiently, the solvent preferably contains a base with a higher pKa and / or has a higher dielectric constant. For example, the solvent preferably contains a base with a pKa greater than 6 and / or has a dielectric constant greater than 6. Without being bound by theory, a base with a higher pKa has a greater ability to trap hydrochloric acid, a by-product of the esterification reaction, and therefore tends to maintain a higher pKa of the reaction system. Therefore, it is believed that when the solvent contains a base with a higher pKa, the formation of four or more ester bonds is promoted. It is also believed that using a solvent with a dielectric constant greater than 6 facilitates the progress of ionic reactions, thereby facilitating the formation of four or more ester bonds.

[0037] Any base having a pKa of greater than 6 can be used as long as the effects of the present invention can be obtained. Non-limiting examples include diisopropylethylamine (iPr ２ Any solvent having a dielectric constant of greater than 6 can be used as long as the effects of the present invention can be obtained, and non-limiting examples include 1,2-dichloroethane (dielectric constant 10.4) and dichloromethane (dielectric constant 9.1).

[0038] In the ester bond-forming reaction, the yield of tri(hydroxycinnamoyl)quinic acid protected with a silyl-protecting group, using a hydroxycinnamic acid protected with a silyl-protecting group as a starting material, may be 10% or more, 20% or more, 30% or more, or 40% or more, or may be 10 to 90%, 10 to 80%, 10 to 70%, 10 to 60%, 10 to 50%, 10 to 40%, 10 to 30%, 10 to 20%, 20 to 90%, 20 to 80%, 20 to 70%, 20 to 60%, 30 to 90%, 30 to 80%, 30 to 70%, 30 to 60%, 40 to 90%, 40 to 80%, 40 to 70%, or 40 to 60%.

[0039] In the ester bond-forming reaction, the yield of tetra(hydroxycinnamoyl)quinic acid protected with a silyl protecting group, using a hydroxycinnamic acid protected with a silyl protecting group as a starting material, may be 0% or more, 5% or more, 10% or more, 20% or more, 30% or more, or 40% or more, or alternatively, 0 to 90%, 0 to 80%, 0 to 70%, 0 to 60%, 0 to 50%, 0 to 40%, 0 to 30%, 0 to 20%, 0 to 10%, 0 to 5%, 5 to 90%, 5 to 50%, 5 to 60%, 5 to 90%, 5 to 10 ... It may be up to 80%, 5 to 70%, 5 to 60%, 5 to 50%, 5 to 40%, 5 to 30%, 5 to 20%, 5 to 10%, 10 to 90%, 10 to 80%, 10 to 70%, 10 to 60%, 10 to 50%, 10 to 40%, 10 to 30%, 10 to 20%, 20 to 90%, 20 to 80%, 20 to 70%, 20 to 60%, 30 to 90%, 30 to 80%, 30 to 70%, 30 to 60%, 40 to 90%, 40 to 80%, 40 to 70%, or 40 to 60%.

[0040] Furthermore, in the ester bond-forming reaction, the yield of tetra(hydroxycinnamoyl)quinic acid protected with a silyl protecting group, using hydroxycinnamic acid protected with a silyl protecting group as the starting material, may be 20% or less, 10% or less, 5% or less, or 1% or less, or may be 0 to 20%, 0 to 10%, 0 to 5%, or 0 to 1%. When it is desired to synthesize tri(hydroxycinnamoyl)quinic acid preferentially in the ester bond-forming reaction, the yield of tetra(hydroxycinnamoyl)quinic acid protected with a silyl protecting group is preferably within these ranges.

[0041] In the ester bond-forming reaction, the yield of silyl-protecting tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid can be adjusted by adjusting the molar ratio of silyl-protecting hydroxycinnamic acid to quinic acid. That is, in the ester bond-forming reaction, by lowering the ratio of silyl-protecting hydroxycinnamic acid to quinic acid, the yield of silyl-protecting tri(hydroxycinnamoyl)quinic acid can be increased, and by increasing the ratio of silyl-protecting hydroxycinnamic acid to quinic acid, the yield of silyl-protecting tetra(hydroxycinnamoyl)quinic acid can be increased.

[0042] The temperature of the ester bond-forming reaction is appropriately set within a range in which the effects of the present invention can be obtained. The temperature can be appropriately adjusted so as to obtain the above-mentioned preferred yield. The temperature may be, for example, 20 to 30°C, or may be room temperature.

[0043] The time for the ester bond-forming reaction is appropriately set within a range in which the effects of the present invention can be obtained. The time can be appropriately adjusted so as to obtain the preferred yield described above. The time may be, for example, 8 to 120 hours, or 48 to 96 hours.

[0044] The ester bond-forming reaction can be terminated by adding a reaction-terminating reagent. Any reagent can be used as the reaction-terminating reagent as long as the effects of the present invention can be obtained, but it is preferable to use an excess amount of water relative to the reaction reagent.

[0045] The tri(hydroxycinnamoyl)quinic acid, tetra(hydroxycinnamoyl)quinic acid, or a mixture thereof protected with a silyl protecting group, which is produced by the ester bond formation reaction, can be purified by a known purification method. Furthermore, the tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid contained in the mixture can be isolated and purified individually or either one of them by a known purification method. Non-limiting examples of known purification methods include extraction with ethyl acetate, n-hexane, or the like, and chromatography using silica gel, activated carbon, Celite, or the like as a carrier.

[0046] <Third Step> In the third step, the silyl protecting group is removed from the phenolic hydroxy group protected with the silyl protecting group.

[0047] The third step can be carried out, for example, as follows. The tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid protected with a silyl protecting group obtained in the second step described above is treated with a deprotecting reagent in a solvent (e.g., dichloromethane, toluene, benzene, tetrahydrofuran, dimethylformamide, etc.) to produce tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid from which the silyl protecting group has been removed. Any deprotecting reagent for removing the silyl protecting group can be used as long as the effects of the present invention can be achieved, but a stoichiometric or greater amount of a fluorine compound is preferably used. Non-limiting examples of the fluorine compound include tetrabutylammonium fluoride (TBAF), tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, pyridinium fluoride, and tris(dimethylamino)sulfonium difluorotrimethylsilicate.

[0048] In the above deprotection reaction, the yield of the reaction in which the silyl protecting group is removed from tri(hydroxycinnamoyl)quinic acid protected with the silyl protecting group is preferably 75% or more, more preferably 80% or more, or preferably 75 to 90%, more preferably 80 to 85%. In the above deprotection reaction, the yield of the reaction in which the silyl protecting group is removed from tetra(hydroxycinnamoyl)quinic acid protected with the silyl protecting group is preferably 55% or more, more preferably 60% or more, or preferably 55 to 70%, more preferably 55 to 65%. When an additional step of removing a methyl group described below is performed, these yields may be the yield of a combined reaction including the silyl protecting group removal reaction and the methyl group removal reaction.

[0049] The temperature for the silyl protecting group elimination reaction is appropriately set within a range that achieves the effects of the present invention. The temperature can be appropriately adjusted so as to obtain the preferred yield described above. The temperature may be, for example, 20 to 30°C, or may be room temperature.

[0050] The reaction time for removing the silyl protecting group is appropriately set within a range in which the effects of the present invention can be obtained. The reaction time can be appropriately adjusted so as to obtain the above-mentioned preferred yield. The reaction time may be, for example, 1 to 8 hours, or 2 to 6 hours.

[0051] In a silyl protecting group elimination reaction using a fluorine compound (e.g., tetrabutylammonium fluoride (TBAF)), a reagent can be used to efficiently remove the by-products, ammonium salt and silyl fluoride. Any reagent can be used as the reagent as long as the effects of the present invention can be obtained. For example, a solution containing calcium carbonate, a cation exchange resin (e.g., DOWEX 50WX8-400), and / or methanol is preferably used.

[0052] The tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid from which the silyl protecting groups have been removed, produced by the above-mentioned deprotection reaction, can be purified by known purification methods, including, but not limited to, extraction with ethyl acetate, n-hexane, etc., and chromatography using silica gel, activated carbon, Celite, etc. as a carrier.

[0053] <Total Yield> In the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, the total yield of the series of reactions up to obtaining tri(hydroxycinnamoyl)quinic acid, using hydroxycinnamic acid as a starting material, may be 5% or more, 10% or more, 20% or more, or 30% or more, or alternatively, 5 to 90%, 5 to 80%, 5 to 70%, 5 to 60%, 5 to 50%, 5 to 40%, 5 to 30%, 5 to 20%, 5 to 10%, 10 to 90%, 10 to 80%, 10 to 70%, 10 to 60%, 10 to 50%, 20 to 90%, 20 to 80%, 20 to 70%, 20 to 60%, 20 to 50%, 30 to 90%, 30 to 80%, 30 to 70%, 30 to 60%, or 30 to 50%. In one embodiment of the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, the total yield of the series of reactions to obtain tetra(hydroxycinnamoyl)quinic acid using hydroxycinnamic acid as a starting material may be 0% or more, 5% or more, 10% or more, 20% or more, or 30% or more, or alternatively, 0 to 90%, 0 to 80%, 0 to 70%, 0 to 60%, 0 to 50%, 0 to It may be 40%, 0-30%, 0-20%, 0-10%, 5-90%, 5-80%, 5-70%, 5-60%, 5-50%, 5-40%, 5-30%, 5-20%, 5-10%, 10-90%, 10-80%, 10-70%, 10-60%, 10-50%, 20-90%, 20-80%, 20-70%, 20-60%, 20-50%, 30-90%, 30-80%, 30-70%, 30-60%, or 30-50%. It may also be 20% or less, 10% or less, 5% or less, or 1% or less, or 0-20%, 0-10%, 0-5%, or 0-1%.

[0054] In the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetracaffeoylquinic acid, the yield of tri(hydroxycinnamoyl)quinic acid and tetra(hydroxycinnamoyl)quinic acid can be adjusted by adjusting the type and composition of the base and / or solvent that can be used in the second step described above.

[0055] Furthermore, in one embodiment of the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, the yield of tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid can be adjusted by adjusting the molar ratio of hydroxycinnamic acid to quinic acid in the second step described above.

[0056] <Additional Step of Protecting the Carboxy Group of Quinic Acid with a Methyl Group> The method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to one embodiment may include an additional step of protecting the carboxy group of quinic acid with a methyl group prior to the second step. By including this additional step, the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid according to one embodiment can produce tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid more efficiently. Furthermore, using a methyl group as the protecting group for the carboxy group of quinic acid tends to facilitate a reduction in the number of steps.

[0057] (Introduction of Methyl Group) A methyl group is introduced into a carboxy group of quinic acid by reacting quinic acid with a methyl group introduction reagent. Any reagent can be used as the methyl group introduction reagent as long as the effects of the present invention can be obtained, but for example, acetyl chloride is preferably used. The molar ratio of quinic acid to the methyl group introduction reagent in the methyl group introduction reaction can be any as long as the effects of the present invention can be obtained. The molar ratio of quinic acid to the methyl group introduction reagent is preferably 10:1 to 1:10, more preferably 3:1 to 1:1.

[0058] The methyl group introduction reaction can be carried out in any solvent as long as the effects of the present invention can be obtained. Non-limiting examples of the solvent include methanol, dichloromethane, toluene, benzene, tetrahydrofuran, dimethylformamide, etc.

[0059] The yield of the methyl group introduction reaction is preferably 95% or more, more preferably 98% or more, or may be quantitative.

[0060] The temperature of the methyl group introduction reaction is appropriately set within a range in which the effects of the present invention can be obtained. The temperature can be appropriately adjusted so as to obtain the above-mentioned preferred yield. The temperature may be, for example, 20 to 30°C, or may be room temperature.

[0061] The time for the methyl group introduction reaction is appropriately set within a range in which the effects of the present invention can be obtained. The time can be appropriately adjusted so as to obtain the preferred yield described above. The time may be, for example, 1 to 48 hours, or 8 to 24 hours.

[0062] <Additional Step of Removing Methyl Groups from Methyl-Protected Carboxy Groups> In one embodiment, when the quinic acid used in Step 2 is a quinic acid whose carboxy groups are protected with methyl groups, the method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid may include an additional step of removing the methyl groups from the methyl-protected carboxy groups after Step 2. This additional step of removing the methyl groups from the methyl-protected carboxy groups is carried out, for example, together with the additional step of protecting the carboxy groups of quinic acid with methyl groups.

[0063] The additional step of removing the methyl group is preferably carried out simultaneously with and / or after the third step.

[0064] In the additional step of removing a methyl group, the reaction of removing a methyl group from a carboxy group protected by a methyl group may be carried out at least partially as a side reaction of the reaction of removing a silyl protecting group from a phenolic hydroxy group in the above-mentioned step 3. In this case, the deprotecting reagent (e.g., a fluorine compound such as tetrabutylammonium fluoride (TBAF)) that removes the silyl protecting group in step 3 also functions as a deprotecting reagent that removes methyl groups from some or all of the carboxy groups protected by a methyl group. Furthermore, the additional step of removing a methyl group may include, during or after step 3, performing a reaction of removing a methyl group from a carboxy group protected by a methyl group using a deprotecting reagent that removes a methyl group different from the deprotecting reagent that removes the silyl protecting group. As the deprotecting reagent that removes a methyl group, any reagent can be used as long as the effects of the present invention can be obtained. For example, anhydrous lithium bromide, anhydrous lithium iodide, etc. are preferably used.

[0065] When the additional step of removing the methyl group is carried out, the yield of the combined reaction of removing the silyl protecting group and the methyl group from tri(hydroxycinnamoyl)quinic acid or tetra(hydroxycinnamoyl)quinic acid protected with a silyl protecting group and a methyl group is as described above.

[0066] When the additional step of removing the methyl group uses the above-mentioned deprotecting reagent for removing the methyl group (e.g., anhydrous lithium bromide), the methyl group removal reaction is preferably carried out by reacting tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid in which the carboxy group is protected with a methyl group with the deprotecting reagent for removing the methyl group in a solvent (e.g., pyridine).

[0067] The temperature of the methyl group elimination reaction is appropriately set within a range in which the effects of the present invention can be obtained. The temperature can be appropriately adjusted so as to obtain the preferred yield described above. The temperature may be, for example, 20 to 150°C, or 100 to 120°C.

[0068] The time for the methyl group elimination reaction is appropriately set within a range in which the effects of the present invention can be obtained. The time can be appropriately adjusted so as to obtain the preferred yield described above. The time may be, for example, 2 to 12 hours, or 4 to 8 hours.

[0069] The tricaffeoylquinic acid and / or tetracaffeoylquinic acid from which the methyl groups have been removed, produced by the methyl group elimination reaction, can be purified by known purification methods, non-limiting examples of which include extraction with ethyl acetate, n-hexane, etc., and chromatography using silica gel, activated carbon, Celite, etc. as a carrier.

[0070] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below. [1] A method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, comprising: a first step of protecting a phenolic hydroxy group of a hydroxycinnamic acid with a silyl protecting group; a second step of forming an ester bond between a carboxy group of the hydroxycinnamic acid and a hydroxy group of quinic acid after the first step; and a third step of removing the silyl protecting group from the phenolic hydroxy group protected with the silyl protecting group after the second step. [2] The production method according to [1], wherein the hydroxycinnamic acid is caffeic acid, ferulic acid, coumaric acid, or sinapic acid. [3] The method according to [1], wherein the silyl protecting group is -SiR ３ and R is independently C １ -C ６ [4] The method according to [1] or [2], wherein R is independently a hydrocarbon group. １ -C ６ Alkyl group or C ６The method according to [3], wherein the silyl protecting group is an aryl group. [5] The method according to any one of [1] to [4], wherein the silyl protecting group is a tert-butyldimethylsilyl group, a triisopropylsilyl group, a diethylisopropylsilyl group, or a tert-butyldiphenylsilyl group. [6] The method according to any one of [1] to [5], wherein the second step comprises forming an ester bond between a carboxy group of hydroxycinnamic acid and a hydroxy group of quinic acid in a solvent containing one or more bases. [7] The method according to [6], wherein the solvent comprises dimethylaminopyridine. [8] The method according to [6] or [7], wherein the solvent comprises a base having a pKa of 6 or less and has a dielectric constant of 6 or less. [9] The method according to any one of [1] to [8], wherein the third step comprises removing the silyl protecting group from a phenolic hydroxy group protected with the silyl protecting group in the presence of a fluorine compound.

[10] The method according to [9], wherein the fluorine compound is tetrabutylammonium fluoride.

[11] The manufacturing method according to any one of [1] to

[10] , further comprising: a step of protecting a carboxy group of quinic acid with a methyl group before the second step; and a step of removing the methyl group from the carboxy group protected with the methyl group after the second step. Each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications of configurations are possible as appropriate within the scope of the present disclosure.

[0071] The present disclosure will be explained in more detail below by showing examples, but interpretation of the present disclosure is not limited to these examples.

[0072] Example 1 Synthesis of Tricaffeoylquinic Acid and Tetracaffeoylquinic Acid Using tert-butyldimethylsilyl Chloride as a Silyl Protecting Group In Example 1, tricaffeoylquinic acid and tetracaffeoylquinic acid were produced according to the reaction scheme shown in Figure 1. In this reaction scheme, tert-butyldimethylsilyl chloride (TBS-Cl) was used as the silyl protecting group. The reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out using diisopropylethylamine (iPr ２ EtN) in dichloromethane as solvent.

[0073] Synthesis of 3,4-di-O-tert-butyldimethylsilyl caffeic acid (2). Caffeic acid (1) (7.20 g, 40.0 mmol) and imidazole (18.8 g, 276 mmol) were dissolved in dimethylformamide (40 mL). To the solution was added dropwise tert-butyldimethylsilyl chloride (TBS-Cl) (20.0 g, 132 mmol), a silyl protecting group, and the mixture was stirred at room temperature for 12 hours. Water (300 mL) was added to terminate the reaction, and the reaction solution was extracted twice with 200 mL of n-hexane:ethyl acetate (1:1). The organic layer was separated, washed with saturated brine, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure to obtain a crude product (24.86 g). This crude product was dissolved in 400 mL of methanol:water (1:1), 10 g (72.4 mmol) of potassium carbonate was added, and the mixture was stirred at room temperature for 12 hours. After stirring, the reaction mixture was neutralized with 3% aqueous hydrochloric acid, and the product was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, and the organic solvent was removed under reduced pressure to give 3,4-di-O-tert-butyldimethylsilyl caffeic acid (2) (14.51 g, 35.5 mmol, white crystals) in a yield of 88.8%.

[0074] [Synthesis of methyl quinate (5)] (-)-quinic acid (4) (10.0 g, 52.04 mmol) was suspended in methanol (MeCH, 35 mL) and cooled to 0°C under a nitrogen atmosphere. Acetyl chloride (2.04 g, 26.0 mmol) was added dropwise to the suspension, and the resulting suspension was warmed to room temperature and stirred for 16 hours. The reaction mixture was concentrated under reduced pressure to remove volatile components such as methanol. Chloroform and methanol as an azeotrope were added to the concentrated residue, and then these were distilled off to obtain methyl quinate (5) (10.7 g, quantitative yield).

[0075] [Synthesis of methyl 3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (6) and methyl 1,3,4,5-tetrakis(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (8)] A few drops of dimethylformamide were added to a solution of 3,4-di-O-tert-butyldimethylsilylcaffeoyl (2) (3.48 g, 8.51 mmol, 3.5 eq. mol) in 10 mL of 1,2-dichloroethane (EDC), and oxalyl chloride ((COCl ２ ) ２ , 3.20 g, 25.5 mmol) was added dropwise and stirred at room temperature for 1 hour. After stirring, excess oxalyl chloride and the solvent 1,2-dichloroethane were distilled off under vacuum to obtain crude acid chloride (3). The crude acid chloride (3) was dissolved in 20 mL of dichloromethane, and this was mixed with methyl quinate (5) (0.50 g, 2.43 mmol), dimethylaminopyridine (DMAP, 0.2 g), and diisopropylethylamine (iPr ２The mixture was added dropwise to a solution of 1,3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (6) and 1,3,4,5-tetrakis(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (8) in 20 mL of dichloromethane, and stirred at room temperature for 72 hours. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with dilute hydrochloric acid and dilute aqueous sodium bicarbonate, and then with water and saturated brine. The mixture was dried over anhydrous sodium sulfate, and the solvent was evaporated to obtain a mixed crude product (4.13 g) containing methyl 3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (6) and methyl 1,3,4,5-tetrakis(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (8). This mixed crude product was purified by column chromatography (mobile phase: n-hexane / ethyl acetate=9 / 1 to 7 / 1) using 60 g of silica gel (Wakogel (registered trademark) 60N, 150 to 425 μm) to obtain methyl 3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (6) (1.48 g, 1.07 mmol, yield: 44.2%) and methyl 1,3,4,5-tetrakis(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (8) (0.64 g, 0.362 mmol, yield: 14.9%).

[0076] [Synthesis of methyl 3,4,5-tri-caffeoylquinate] To a solution of methyl 3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (6) (3.01 g, 2.18 mmol) in tetrahydrofuran (35 mL), tetrabutylammonium fluoride (TBAF) (1 mol / L tetrahydrofuran solution) (16 mL, 16 mmol) was added and the mixture was stirred at room temperature for 3.5 hours. The disappearance of the raw materials over the 3.5 hour reaction time was confirmed by HPLC. Calcium carbonate (3.20 g, 32 mmol), DOWEX 50WX8-400 (15.0 g), and methanol (20 mL) were added and the mixture was stirred at room temperature for 1 hour. The mixture was filtered through Celite 545, and the solid on the Celite 545 was thoroughly washed with methanol. The filtrate was concentrated under reduced pressure to obtain the crude product (1.79 g). HPLC analysis confirmed that the crude product contained methyl 3,4,5-triscaffeoylquinate and a small amount of 3,4,5-tri-caffeoylquinic acid (TCQA). The crude product was used as is in the next reaction.

[0077] [Synthesis of 3,4,5-tri-caffeoylquinic acid (TCQA) (7)] A mixture of 1.79 g of a crude product containing methyl 3,4,5-triscaffeoylquinate and 3,4,5-triscaffeoylquinic acid, anhydrous lithium bromide (4.5 g, 52 mmol), and pyridine (30 mL) was heated and stirred at 110°C for 6.5 hours. The disappearance of the raw materials and completion of the reaction were confirmed by HPLC. The pyridine solvent was distilled off under reduced pressure. After cooling, water was added to the reaction solution, and dilute hydrochloric acid was added until the aqueous layer became acidic. The organic layer was extracted with ethyl acetate. The organic layer was washed with dilute hydrochloric acid to remove the pyridine. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The extraction solvent was then distilled off under reduced pressure to obtain a crude product (1.64 g). The crude product was purified by silica gel column chromatography (silica gel 15 g, mobile phase: ethyl acetate / methanol / formic acid=9 / 1 / 0.1) to obtain 1.08 g (1.59 mmol, yield 86%) of 3,4,5-triscaffeoylquinic acid (TCQA).

[0078] In the reaction scheme of Figure 1, the total yield of the series of reactions leading to the production of 3,4,5-tri-caffeoylquinic acid (TCQA) (7) was 34% starting from caffeic acid (1).

[0079] [Synthesis of methyl 1,3,4,5-tetra-caffeoylquinate] To a solution of methyl 1,3,4,5-tetrakis(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (8) (1.75 g, 0.98 mmol) in tetrahydrofuran (50 mL), tetrabutylammonium fluoride (TBAF) (1 mol / L tetrahydrofuran solution) (10 mL, 10 mmol) was added and stirred at room temperature for 3 hours. The disappearance of the raw materials over the 3-hour reaction time was confirmed by HPLC. Calcium carbonate (2.0 g, 20 mmol), DOWEX 50WX8-400 (9.4 g), and methanol (20 mL) were added and stirred at room temperature for 1 hour. The mixture was filtered through Celite 545, and the solid on the Celite 545 was thoroughly washed with methanol. The filtrate was concentrated under reduced pressure to give a crude product of methyl 1,3,4,5-tetra-caffeoylquinate (0.95 g), which was used as it was in the next reaction.

[0080] [Synthesis of 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA) (9)] A mixture of crude methyl 1,3,4,5-tetra-caffeoylquinate (0.95 g), anhydrous lithium bromide (1.5 g, 17.3 mmol), pyridinium bromide (0.5 g, 3.0 mmol), and pyridine (30 mL) was heated and stirred at 110°C for 11.5 hours. The disappearance of the raw materials and completion of the reaction were confirmed by HPLC. The pyridine solvent was distilled off under reduced pressure. After cooling, water was added to the reaction solution, and dilute hydrochloric acid was added until the aqueous layer became acidic. The organic layer was extracted with ethyl acetate. The mixture was filtered through Celite, and the extraction solvent was distilled off under reduced pressure to obtain a crude product (1.38 g). The crude product was roughly purified by silica gel column chromatography (silica gel 6 g, mobile phase: ethyl acetate / methanol / formic acid=9 / 1 / 0.1) to obtain 0.67 g (0.80 mmol, yield 81.3%) of crude 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA). The crude product was purified by silica gel column chromatography (silica gel 10 g, mobile phase: ethyl acetate / methanol / formic acid=9 / 1 / 0.1) to obtain 0.53 g (0.63 mmol, yield 64%) of purified 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA).

[0081] In the reaction scheme of Figure 1, the total yield of the series of reactions leading to the production of 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA) (9) was 9% using caffeic acid (1) as the starting material.

[0082] As described above, tricaffeoylquinic acid and tetracaffeoylquinic acid were effectively produced by the reaction scheme shown in FIG.

[0083] In the above esterification reaction, when 1,2-dichloroethane (EDC) was used as the solvent instead of dichloromethane, the same results as in Example 1 were obtained.

[0084] Example 2: Synthesis of tricaffeoylquinic acid and tetracaffeoylquinic acid using triisopropylsilyl chloride as a silyl protecting group Example 2 In Example 2, tricaffeoylquinic acid and tetracaffeoylquinic acid were produced according to the reaction scheme shown in Figure 2. In this reaction scheme, triisopropylsilyl chloride (TIPSCl) was used as the silyl protecting group. The reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out using diisopropylethylamine (iPr ２ The reaction was carried out in the presence of dichloromethane as a solvent.

[0085] Synthesis of 3,4-di-O-triisopropylsilyl caffeic acid (10). Caffeic acid (1) (3.07 g, 17.0 mmol), imidazole (8.05 g, 118 mmol), and 4-dimethylaminopyridine (DMAP) (0.27 g, 2.2 mmol) were dissolved in DMF (30 mL). Triisopropylsilyl chloride (TIPSCl) (10.85 g, 65.3 mmol) was added dropwise to the solution, and the mixture was stirred at room temperature for 12 hours. Water (100 mL) was added to quench the reaction, and the reaction solution was extracted with ethyl acetate (2 x 100 mL). The organic layer was separated, washed with saturated brine, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure to obtain the crude product, 3,4-di-O-triisopropylsilyl caffeic acid (12.65 g). This crude product was separated by silica gel column chromatography (mobile phase: n-hexane:ethyl acetate (30:1)) to obtain purified 3,4-di-O-triisopropylsilyl caffeic acid (10) (10.96 g, 16.89 mmol) in a yield of 99%.

[0086] [Synthesis of methyl 3,4,5-tris(3,4-di-O-triisopropylsilylcaffeoyl)quinate (12) and methyl 1,3,4,5-tetrakis(3,4-di-O-triisopropylsilylcaffeoyl)quinate (14)] A few drops of dimethylformamide were added to a solution of 3,4-di-O-triisopropylsilylcaffeic acid (10) (4.19 g, 8.51 mmol, 3.5 eq. mol) in 10 mL of 1,2-dichloroethane, and oxalyl chloride (3.20 g, 25.5 mmol) was added dropwise. The mixture was stirred at room temperature for 1 hour. After stirring, excess oxalyl chloride and the solvent 1,2-dichloroethane were distilled off under vacuum. 10 mL of 1,2-dichloroethane was added to the mixture, and low-boiling points such as oxalyl chloride were removed to obtain crude acid chloride. This crude acid chloride was dissolved in 10 mL of dichloromethane, and the solution was mixed with methyl quinate (5) (0.50 g, 2.43 mmol) obtained in the same manner as in Example 1, dimethylaminopyridine (DMAP, 0.2 g), and diisopropylethylamine (iPr ２ The resulting mixture was added dropwise to a solution of 20 mL of dichloromethane containing 2.20 g of EtN (2.20 g, 17.0 mmol) and stirred at room temperature for 72 hours. A small amount of methanol was added to the reaction mixture to quench the reaction, and then water was added and the mixture was extracted with ethyl acetate. The organic layer was washed with dilute hydrochloric acid and dilute aqueous sodium bicarbonate solution, and then with water and saturated brine. The mixture was dried over anhydrous sodium sulfate, and the solvent was evaporated to obtain a crude mixed product (4.66 g). This mixed crude product was purified by silica gel column chromatography (silica gel 60 g, mobile phase: n-hexane / ethyl acetate=9 / 1 to 7 / 1) to obtain methyl 3,4,5-tris(3,4-di-O-triisopropylsilylcaffeoyl)quinate (12) (2.03 g, 1.25 mmol, yield: 51%) and methyl 1,3,4,5-tetrakis(3,4-di-O-triisopropylsilylcaffeoyl)quinate (14) (0.54 g, 0.26 mmol, yield: 11%).

[0087] [Synthesis of methyl 3,4,5-tri-caffeoylquinate] To a solution of methyl 3,4,5-tris(3,4-di-O-triisopropylsilylcaffeoyl)quinate (12) (0.94 g, 0.58 mmol) in tetrahydrofuran (25 mL), tetrabutylammonium fluoride (TBAF) (1 mol / L tetrahydrofuran solution) (8.5 mL, 8.5 mmol) was added and the mixture was stirred at room temperature for 3.5 hours. The disappearance of the starting material over the 3.5 hour reaction time was confirmed by HPLC. Calcium carbonate (1.70 g, 17 mmol), DOWEX 50WX8-400 (8.0 g) (commercially available product) and methanol (10 mL) were added and the mixture was stirred at room temperature for 1 hour. The mixture was filtered through Celite 545, and the solid on the Celite 545 was thoroughly washed with methanol. The filtrate was concentrated under reduced pressure to obtain the crude product (480 mg). HPLC confirmed that the crude product contained mainly methyl 3,4,5-tri-caffeoylquinate, and a small amount of hydrolyzed 3,4,5-tri-caffeoylquinic acid. Since the crude product consisted almost entirely of these two components, it was used directly in the next reaction without further isolation or purification.

[0088] [Synthesis of 3,4,5-tri-caffeoylquinic acid (TCQA) (13)] A mixture of 1.28 g of the crude product of methyl 3,4,5-triscaffeoylquinate and 3,4,5-triscaffeoylquinic acid from the previous step, anhydrous lithium bromide (3.2 g, 37 mmol), and pyridine (30 mL) was heated and stirred at 110°C for 6.5 hours. HPLC confirmed that the reaction was nearly complete after 5.5 hours. The pyridine solvent was distilled off under reduced pressure. After cooling, water was added to the reaction mixture, and dilute hydrochloric acid was added until the aqueous layer became acidic. The organic layer was extracted with ethyl acetate. The organic layer was washed with dilute hydrochloric acid to remove the pyridine. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The extraction solvent was then distilled off under reduced pressure to obtain the crude product (1.35 g, HPLC purity 73%). The crude product was dissolved in methanol and treated with activated carbon. The methanol solvent was removed by distillation under reduced pressure to give a crude product (1.16 g) treated with activated carbon. The crude product was purified by silica gel column chromatography (silica gel: 15 g, mobile phase: ethyl acetate / methanol / formic acid = 9 / 1 / 0.1) to give 3,4,5-tri-caffeoylquinic acid (TCQA) (13) (1.08 g, 1.59 mmol, yield 86%).

[0089] In the reaction scheme of Figure 2, the total yield of the series of reactions leading to the production of 3,4,5-tri-caffeoylquinic acid (TCQA) (13) was 43% starting from caffeic acid (1).

[0090] [Synthesis of methyl 1,3,4,5-tetra-caffeoylquinate] To a solution of methyl 1,3,4,5-tetrakis(3,4-di-O-triisopropylsilylcaffeoyl)quinate (14) (0.42 g, 0.20 mmol) in tetrahydrofuran (20 mL), tetrabutylammonium fluoride (TBAF) (1 mol / L tetrahydrofuran solution) (2.0 mL, 2 mmol) was added and stirred at room temperature for 3 hours. Calcium carbonate (0.40 g, 4.0 mol), DOWEX 50WX8-400 (2.0 g) (commercially available product used as is), and methanol (10 mL) were added and stirred at room temperature for an additional 1 hour. The mixture was filtered through Celite 545, and the solid on the Celite 545 was thoroughly washed with methanol. The washed solid was dissolved in methanol, treated with activated carbon, and filtered through Celite 545. The activated carbon in the filtrate was removed by filter filtration. The filtrate was concentrated under reduced pressure to give the crude product (0.17 g).

[0091] [Synthesis of 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA)] In the same manner as in Example 1, 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA) (15) was obtained from methyl 1,3,4,5-tetra-caffeoylquinate.

[0092] In the reaction scheme of Figure 2, the total yield of the series of reactions leading to the production of 1,3,4,5-tetra-caffeoylquinic acid (tetra-CQA) (15) was 7% starting from caffeic acid (1).

[0093] As described above, tricaffeoylquinic acid and tetracaffeoylquinic acid were effectively produced by the reaction scheme shown in FIG.

[0094] In the above esterification reaction, when 1,2-dichloroethane (EDC) was used as the solvent instead of dichloromethane, the same results as in Example 2 were obtained.

[0095] Example 3: Selective synthesis of tricaffeoylquinic acid (1) In Example 3, as shown in FIG. 3 , the same reaction scheme as in Example 1 was carried out, except that the reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out in the presence of pyridine and 1,4-dioxane as a solvent. The reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out as follows. Crude acid chloride (3) and methyl quinate (5) were obtained in the same manner as in Example 1. Crude acid chloride (3) (1.86 g, 4.29 mmol) was dissolved in 10 ml of 1,4-dioxane, and the solution was added dropwise to a solution of methyl quinate (5) (0.31 g, 1.50 mmol), dimethylaminopyridine (DMAP, 22 mg, 0.10 mmol), and pyridine (1.07 g, 13.6 mmol) in 20 ml of 1,4-dioxane at room temperature. The temperature was gradually raised to the reflux temperature of the solvent, and the mixture was heated and stirred under reflux for 8 hours. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with dilute hydrochloric acid and dilute aqueous sodium carbonate, and the extract was washed with water and saturated brine. The mixture was dried over anhydrous sodium sulfate, and the solvent was distilled off to obtain a crude product (2.18 g) of methyl 3,4,5-tris(3,4-di-O-tert-butyldimethylsilylcaffeoyl)quinate (6). Purification was performed using flash column chromatography (mobile phase: n-hexane / ethyl acetate) to obtain compound 6 (0.55 g, 0.40 mmol, yield: 27%). Note that the production of compound 8 was not observed in these steps (yield: 0%).

[0096] As described above, it was possible to selectively synthesize tricaffeoylquinic acid by carrying out the reaction of forming an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid in the presence of pyridine and 1,4-dioxane as a solvent. Furthermore, as compared with Example 1, it was found that by carrying out the esterification reaction in a solvent with a relatively low dielectric constant such as 1,4-dioxane (relative dielectric constant: 2.2) in the presence of a base with a relatively low acid dissociation constant (pKa) such as pyridine (pKa = 5.2), it was possible to selectively synthesize tricaffeoylquinic acid. ２It was shown that the presence of a base with a relatively high acid dissociation constant (pKa), such as HCl (EtN) (pKa = 11.0), tends to result in more selective synthesis of tricaffeoylquinic acid than when the esterification reaction is carried out in a solvent with a relatively low dielectric constant, such as 1,2-dichloroethane (dielectric constant: 10.4). Without being bound by theory, it is believed that a base with a relatively low pKa has a lower ability to trap hydrochloric acid, a by-product of the esterification reaction, thereby maintaining the pKa of the reaction system at a lower level, thereby suppressing the formation of ester bonds with a value of 4 or more. Furthermore, it is believed that a solvent with a relatively low dielectric constant has an adverse effect on the ionic reaction that produces the salt. As a result, it is believed that tricaffeoylquinic acid was preferentially synthesized in Example 3.

[0097] Example 4: Selective synthesis of tricaffeoylquinic acid (2) In Example 4, as shown in FIG. 4, the same reaction scheme as in Example 2 was carried out, except that the reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out in the presence of pyridine and 1,4-dioxane as a solvent. The reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out as follows. Crude acid chloride (11) and methyl quinate (5) were obtained in the same manner as in Example 2. Crude acid chloride (11) (2.77 g, 4.44 mmol) was dissolved in 10 ml of 1,4-dioxane, and the solution was added dropwise to a solution of methyl quinate (5) (0.32 g, 1.55 mmol), dimethylaminopyridine (DMAP, 22 mg, 0.10 mmol), and pyridine (1.06 g, 13.4 mmol) in 20 ml of 1,4-dioxane at room temperature. The temperature was gradually raised to the reflux temperature of the solvent, and after 2 hours of reaction, a sample of the reaction mixture was taken and analyzed by HPLC. This confirmed the formation of 13.7% (100% area) of the Tri-substituted product. Furthermore, the crude acid chloride (11) (118 mg, 0.23 mmol) was dissolved in 1,4-dioxane (2 ml) and added dropwise to the reaction mixture, followed by heating and stirring under reflux for 3 hours. A small amount of methanol was added to the reaction mixture to quench the reaction, followed by adding water and extracting with ethyl acetate. The organic layer was washed with dilute hydrochloric acid and dilute aqueous sodium carbonate, followed by washing with water and saturated saline. The mixture was dried over anhydrous sodium sulfate, and the solvent was evaporated to obtain the crude product (2.76 g) of methyl 3,4,5-tris(3,4-di-O-triisopropylsilylcaffeoyl)quinate (12). Purification using flash column chromatography (mobile phase: n-hexane / ethyl acetate) gave methyl 3,4,5-tris(3,4-di-O-triisopropylsilylcaffeoyl)quinate (12) (1.06 g, 0.65 mmol, yield: 42%). Note that no production of compound 14 was observed in this step (yield: 0%).

[0098] As described above, it was possible to selectively synthesize tricaffeoylquinic acid by carrying out the reaction of forming an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid in the presence of pyridine and 1,4-dioxane as a solvent. Furthermore, as compared with Example 2, it was found that by carrying out the esterification reaction in a solvent with a relatively low dielectric constant such as 1,4-dioxane (relative dielectric constant: 2.2) in the presence of a base with a relatively low acid dissociation constant (pKa) such as pyridine (pKa = 5.2), it was possible to selectively synthesize tricaffeoylquinic acid. ２ It was shown that tricaffeoylquinic acid tends to be synthesized more selectively in the presence of a base with a relatively high acid dissociation constant (pKa), such as HCl (EtN) (pKa = 11.0), compared to when the esterification reaction is carried out in a solvent with a relatively low dielectric constant, such as 1,2-dichloroethane (dielectric constant: 10.4). Furthermore, a comparison with Example 3 suggests that this tendency is independent of the type of silyl protecting group. As with Example 3, without being bound by theory, it is believed that a base with a relatively low pKa has a lower ability to trap hydrochloric acid, a by-product of the esterification reaction, thereby maintaining a lower pKa of the reaction system and thereby suppressing the formation of ester bonds with a value of 4 or more. Furthermore, it is believed that a solvent with a relatively low dielectric constant acts unfavorably on the ionic reaction that produces the salt. As a result, it is believed that tricaffeoylquinic acid was preferentially synthesized in Example 4.

[0099] Example 5: Synthesis of triferuloyl quinic acid and tetraferuloyl quinic acid In Example 5, triferuloyl quinic acid and tetraferuloyl quinic acid were produced according to the reaction scheme shown in Figure 5. Here, tert-butyldimethylsilyl chloride (TBS-Cl) was used as the silyl protecting group. The reaction to form an ester bond between the carboxy group of caffeic acid and the hydroxy group of quinic acid was carried out in the presence of pyridine using 1,4-dioxane as a solvent.

[0100] [Synthesis of methyl 3,4,5-tris(4-O-tert-butyldimethylsilylferuloyl)quinate (24) and methyl 1,3,4,5-tetrakis(4-O-tert-butyldimethylsilylferuloylferuloyl)quinate (25)] 4-O-tert-butyldimethylsilyl ferulic acid (22) was prepared from ferulic acid (21) by the same method as in the synthesis of 3,4-di-O-tert-butyldimethylsilyl caffeic acid (2) in Example 1. Methyl quinate (5) was prepared in the same manner as in Example 1. A few drops of dimethylformamide were added to a solution of 4-O-tert-butyldimethylsilyl ferulic acid (1.14 g, 3.70 mmol) in 1,2-dichloroethane (10 mL), and oxalyl chloride (2.35 g, 18.5 mmol) was added dropwise, followed by stirring at room temperature for 1 hour. Subsequently, excess oxalyl chloride and the solvent 1,2-dichloroethane were distilled off under vacuum. 10 ml of 1,2-dichloroethane was added to the mixture, and the mixture was evaporated to dryness under vacuum twice to remove low-boiling components such as oxalyl chloride, yielding crude acid chloride (23). A solution of crude acid chloride (23) (2.69 g, 8.24 mmol) in 10 ml of 1,4-dioxane was added dropwise to a solution of methyl quinate (5) (0.52 g, 2.50 mmol), dimethylaminopyridine (20 mg, 0.16 mmol), and pyridine (1.30 g, 16.5 mmol) in 1,4-dioxane (10 ml). The mixture was heated and stirred at 90°C for 4 hours. A small amount of methanol was added to the reaction mixture to quench the reaction, followed by addition of water and extraction with ethyl acetate. The organic layer was washed with dilute hydrochloric acid and dilute aqueous sodium carbonate, followed by water and saturated brine. The mixture was dried over anhydrous sodium sulfate, and the solvent was evaporated to give a mixed crude product (3.42 g). This mixed crude product was purified by flash column chromatography (mobile phase: n-hexane / ethyl acetate gradient) to give methyl 3,4,5-tris(4-O-tert-butyldimethylsilylferuloyl)quinate (24) (1.17 g, 1.086 mmol, yield: 43%) and methyl 1,3,4,5-tetrakis(4-O-tert-butyldimethylsilylferuloyl)quinate (25) (0.38 g, 0.278 mmol, yield: 11%).

[0101] [Synthesis of 3,4,5-trisferuloylquinic acid (28)] To a solution of methyl 3,4,5-tris(4-O-tert-butyldimethylsilylferuloyl)quinate (24) (1.15 g, 1.07 mmol) in tetrahydrofuran (15 ml), tetrabutylammonium fluoride (TBSF) (1 mol / L tetrahydrofuran solution) (4.0 ml, 4 mmol) was added and stirred at room temperature for 2 hours. Further, calcium carbonate (800 mg, 8.0 mol), DOWEX 50WX8-400 (2.40 g), and methanol (6 ml) were added and stirred at room temperature for 1 hour. Filtration was performed using Celite 545, and the solid on Celite 545 was thoroughly washed with methanol. The filtrate was concentrated under reduced pressure to obtain the crude product (0.87 g). This crude product was purified by silica gel column chromatography (eluent: dichloromethane / THF mixture) to obtain methyl 3,4,5-tris-feruloylquinate (26) (680 mg, 0.926 mmol, 87% yield). A mixture of methyl 3,4,5-tris-feruloylquinate (26) (0.24 g, 0.33 mmol), anhydrous lithium bromide (0.88 g, 6.6 mmol, 20 eq. mol), and pyridine (10 ml) was heated and stirred at 110°C for 4.5 hours. After cooling, water was added to the reaction solution, and dilute hydrochloric acid was added until the aqueous layer became acidic. The organic layer was extracted with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The extraction solvent was then evaporated under reduced pressure to obtain 0.27 g of crude product. The crude product was purified by reverse-phase HPLC (ODS column) to give 3,4,5-trisferuloylquinic acid (28) (150 mg, 0.21 mmol, yield 64%).

[0102] [Synthesis of 1,3,4,5-tetrakisferuloylquinic acid (29)] To a solution of methyl 1,3,4,5-tetrakis(4-O-tert-butyldimethylsilylferuloyl)quinate (25) (0.77 g, 0.61 mmol) in tetrahydrofuran (30 ml), tetrabutylammonium fluoride (TBSF) (1 mol / L tetrahydrofuran solution) (3.0 ml, 3 mmol) was added and stirred at room temperature for 1.5 hours. Calcium carbonate (0.60 g, 6.0 mol), DOWEX 50WX8-400 (3.0 g), and methanol (10 ml) were added and stirred at room temperature for 1 hour. The mixture was filtered through Celite 545, and the solid on the Celite 545 was thoroughly washed with methanol. The filtrate was concentrated under reduced pressure to obtain methyl 1,3,4,5-tetrakisferuloylquinate (27) (0.56 g, quantitative yield). A mixture of methyl 1,3,4,5-tetrakisferuloylquinate (27) (1.01 g, 1.09 mmol), anhydrous lithium bromide (1.30 g, 15.0 mmol, 15 eq. mol), and pyridine (10 ml) was heated and stirred at 115°C for 6.5 hours. After 6.5 hours of reaction, almost all of the raw materials had disappeared. The pyridine solvent was distilled off under vacuum. After cooling, water was added to the reaction solution, and dilute hydrochloric acid was added until the aqueous layer became acidic. The organic layer was extracted with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The extraction solvent was then distilled off under reduced pressure to obtain the crude product (0.95 g). This crude product was purified by silica gel column chromatography (mobile phase: ethyl acetate / acetic acid = 90 / 1) to obtain 1,3,4,5-tetrakisferuloylquinic acid (29) (0.88 g, 0.97 mmol, yield: 89%).

[0103] As described above, triferuloyl quinic acid and tetraferuloyl quinic acid were effectively produced by the reaction scheme shown in FIG.

[0104] The method of the present embodiment has industrial applicability because it can effectively produce hydroxycinnamoylquinic acids that are useful as active ingredients in medicines, foods, cosmetics, etc.

Claims

1. A method for producing tri(hydroxycinnamoyl)quinic acid and / or tetra(hydroxycinnamoyl)quinic acid, comprising: a first step of protecting the phenolic hydroxy group of a hydroxycinnamic acid with a silyl protecting group; a second step, after the first step, of forming an ester bond between the carboxy group of the hydroxycinnamic acid and the hydroxy group of quinic acid; and a third step, after the second step, of removing the silyl protecting group from the phenolic hydroxy group protected with the silyl protecting group.

2. The method of claim 1, wherein the hydroxycinnamic acid is caffeic acid, ferulic acid, coumaric acid, or sinapic acid.

3. The silyl protecting group is -SiR ３ and R is independently C １ -C ６ The method according to claim 1 or 2, wherein the alkyl group is a hydrocarbon group.

4. R independently １ -C ６ Alkyl group or C ６ The method according to claim 3 , wherein the alkyl group is an aryl group.

5. The method according to claim 1 or 2, wherein the silyl protecting group is a tert-butyldimethylsilyl group, a triisopropylsilyl group, a diethylisopropylsilyl group, or a tert-butyldiphenylsilyl group.

6. The method of claim 1 or 2, wherein the second step comprises forming an ester bond between a carboxy group of the hydroxycinnamic acid and a hydroxy group of the quinic acid in a solvent containing one or more bases.

7. The process of claim 6, wherein the solvent comprises dimethylaminopyridine.

8. The method of claim 6, wherein the solvent contains a base with a pKa of 6 or less and has a dielectric constant of 6 or less.

9. The method according to claim 1 or 2, wherein the third step comprises removing the silyl protecting group from the phenolic hydroxy group protected with the silyl protecting group in the presence of a fluorine compound.

10. The method according to claim 9, wherein the fluorine compound is tetrabutylammonium fluoride.

11. The method according to claim 1 or 2, further comprising the steps of: protecting the carboxy group of quinic acid with a methyl group before the second step; and removing the methyl group from the carboxy group protected with the methyl group after the second step.

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