JP4637782B2 - Method for determining absolute configuration of organic acid having asymmetric carbon - Google Patents

Description

The present invention relates to a method for determining the absolute configuration of an organic acid having an asymmetric carbon.

  Conventionally, as a method for determining the absolute configuration of a chiral compound, a circular dichroism (CD) spectrophotometric analysis is performed on a complex of a chiral compound and a specific compound (for example, a complex), and the sign of the Cotton effect and the chiral compound A method for determining the absolute configuration of a chiral compound by utilizing the correlation with the absolute configuration of is used. For example, the following non-patent documents 1 to 4 have a description regarding such an absolute configuration determination method.

  Non-Patent Document 1 describes that circular dichroism is induced by coordination of a chiral compound to a porphyrin dimer crosslinked with a long crosslinking chain, and the absolute configuration of the chiral compound can be determined from the sign of the Cotton effect. Has been.

  However, the method described in Non-Patent Document 1 can only be applied to diamines, amino alcohols and the like that are bifunctional chiral compounds.

  Non-Patent Document 2 describes that a porphyrin dimer having a phenylboronic acid unit exhibits circular dichroism in the presence of various sugars.

  However, the method described in Non-Patent Document 2 is applicable only to polyols (polyhydric alcohols) that form a bond with boronic acid, and the absolute configuration around a specific (one) asymmetric center. It is not a method that can determine directly.

  Non-Patent Document 3 describes that a lanthanide tris (β-diketonato) complex exhibits circular dichroism in the presence of a chiral amino alcohol.

  However, the method described in Non-Patent Document 3 is only applicable to chiral amino alcohols.

  Non-Patent Document 4 describes that the absolute configuration of amino acids and amino alcohols can be determined by the circular dichroism of a copper complex.

  However, the method described in Non-Patent Document 4 can be applied only to amino acids and amino alcohols that can be bidentately coordinated with copper.

  As described above, an effective method for determining the absolute configuration of an organic acid having an asymmetric carbon and a salt thereof has not yet been reported.

  On the other hand, an X-ray diffraction method is known as a method for determining the absolute configuration of a chiral compound.

However, this method has a limitation that it can be applied only to crystalline compounds.
J. et al. Am Chem. Soc. 1998, 120, 6185-6186, X. Huang, B.H. H. Rickmann, B.M. Borhan, N .; Berova, K.M. Nakanishi Bull. Chem. Soc. , Jpn. 1998, 71, 1117-1123, M .; Takeuchi, T .; Imada, S.M. Shinkai J. et al. Chem. Soc. Dalton Trans. 1999, 11-12, H .; Tsukube, M.M. Hosokubo. M.M. Wada, S.W. Shinoda, H .; Tamiaki Org. Lett. 1999, 1, 861-864, S .; Zahn, J. et al. W. Canada

  The main object of the present invention is to provide a method capable of easily and accurately determining the absolute configuration of an organic acid having an asymmetric carbon.

  As a result of intensive studies, the present inventor has found that a method using a specific compound can achieve the above object, and has completed the present invention.

That is, the present invention relates to the following absolute configuration determination method.
1. A method for determining the absolute configuration of an organic acid having an asymmetric carbon,
(1) The following chemical formula (I)

[Wherein, R ^a , R ^b , R ^c and R ^d are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an oxygen-containing substituent, a nitrogen-containing substituent, a halogen atom and a halogen atom. 1 type selected from the group consisting of activated hydrocarbon groups, provided that at least one of R ^a , R ^b , R ^c and R ^d is a hydrocarbon group having 1 to 8 carbon atoms, oxygen-containing substitution 1 type selected from the group consisting of a group, a nitrogen-containing substituent, a halogen atom and a halogenated hydrocarbon group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different and each represents one selected from the group consisting of a hydrogen atom, a hydrocarbon group, a halogen atom and a halogenated hydrocarbon group. ]
A reagent containing as an active ingredient a porphyrin dimer represented by:
(2) (i) an organic acid that can be coordinated to a porphyrin dimer and in which a group that can be coordinated to the porphyrin dimer and an asymmetric carbon are directly bonded, or (ii) a porphyrin dimer A circular dichroism spectrophotometric analysis is performed on a sample solution including an organic acid that can be coordinated to a body and has a carbon atom intervening between the coordinateable group and the asymmetric carbon. And determining the absolute configuration of the asymmetric carbon of the organic acid from the sign of the cotton effect.
2. The method according to claim 1, wherein the organic acid is a sulfonic acid or a carboxylic acid.
3. The method of Claim 1 or 2 which performs a circular dichroism spectrophotometric analysis in -30-30 degreeC.

  According to the absolute configuration determining method of the present invention, the absolute configuration of an organic acid having an asymmetric carbon can be determined easily and accurately. Specifically, according to the method of the present invention, an organic acid having an asymmetric carbon is directly bonded to a group (i) capable of coordinating to a porphyrin dimer and capable of coordinating to a porphyrin dimer. Or (ii) an absolute configuration of an asymmetric carbon that can be coordinated to a porphyrin dimer and in which one carbon atom is interposed between the coordinated group and the asymmetric carbon. It can be determined easily and accurately.

  Furthermore, the method of the present invention has the following advantages (1) to (6).

  (1) The absolute configuration of the asymmetric carbon of the organic acid can be determined without complicated operations such as cooling the sample solution.

  (2) The organic acid and porphyrin dimer used in the method of the present invention are both minimal. That is, the method of the present invention can measure a circular dichroism (CD) spectrum with high sensitivity by using a very small amount of an organic acid and a porphyrin dimer.

  (3) In the method of the present invention, it is not necessary to introduce a special modifying group into the organic acid to be measured when measuring a circular dichroism (CD) spectrum. Therefore, the organic acid can be easily recovered as necessary. For example, when the sample solution after measurement and a hydrochloric acid aqueous solution of about 2 mol / l are stirred, the complex composed of the porphyrin dimer and the organic acid is decomposed into the porphyrin dimer and the hydrochloride of the organic acid. Thereby, an organic acid and a porphyrin dimer can be separated and recovered. The porphyrin dimer separated and recovered can be used again.

  (4) According to the method of the present invention, the absolute configuration of the asymmetric carbon of the organic acid can be determined very quickly. The time required for sample preparation and CD spectrum measurement is within 10 minutes depending on conditions.

  (5) Cotton effect detection, that is, CD spectrum measurement is usually performed at 400 to 450 nm. Since absorption of most organic acids is 400 nm or less, the peak showing the Cotton effect does not overlap with the peak shown by the organic acid itself. Thus, according to the method of the present invention, it is possible to determine the absolute configuration for a very wide range of organic acids.

  (6) According to the method of the present invention, the absolute configuration of the asymmetric carbon can be determined for the non-crystalline organic acid.

  The present invention relates to a method for determining the absolute configuration of an organic acid having an asymmetric carbon, and (1) the following chemical formula (I)

[Wherein, R ^a , R ^b , R ^c and R ^d are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an oxygen-containing substituent, a nitrogen-containing substituent, a halogen atom and a halogen atom. 1 type selected from the group consisting of activated hydrocarbon groups, provided that at least one of R ^a , R ^b , R ^c and R ^d is a hydrocarbon group having 1 to 8 carbon atoms, oxygen-containing substitution 1 type selected from the group consisting of a group, a nitrogen-containing substituent, a halogen atom and a halogenated hydrocarbon group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different and each represents one selected from the group consisting of a hydrogen atom, a hydrocarbon group, a halogen atom and a halogenated hydrocarbon group. A reagent comprising an active ingredient of a porphyrin dimer represented by formula (2): (2) (i) a group capable of coordinating to a porphyrin dimer and capable of coordinating to a porphyrin dimer and an asymmetric group It can be coordinated to an organic acid or (ii) porphyrin dimer directly bonded to carbon, and one carbon atom is interposed between the coordinateable group and the asymmetric carbon. The present invention relates to a method for performing circular dichroism (CD) spectrophotometric analysis on a sample solution containing an organic acid and determining the absolute configuration of the asymmetric carbon of the organic acid from the sign of the Cotton effect.

  In the present invention, the absolute configuration of the asymmetric carbon of the organic acid can be easily and accurately determined by using a free porphyrin dimer as in the chemical formula (I) as an active ingredient of the reagent. it can. In particular, the method of the present invention is effective as a means for determining the absolute configuration of asymmetric carbons of carboxylic acid and sulfonic acid.

Reagents containing porphyrin dimer as an active ingredient In the absolute configuration determining method of the present invention (hereinafter sometimes simply referred to as “method of the present invention”), the porphyrin dimer represented by the above chemical formula (I) is used. (Hereinafter, it may be abbreviated as “Compound 1”) is used as an active ingredient.

In the above chemical formula (I), R ^a , R ^b , R ^c and R ^d are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an oxygen-containing substituent, a nitrogen-containing substituent, or a halogen. 1 type selected from the group which consists of an atom and a halogenated hydrocarbon group is shown. However, at least one of R ^a , R ^b , R ^c and R ^d is a hydrocarbon group having 1 to 8 carbon atoms, an oxygen-containing substituent, a nitrogen-containing substituent, a halogen atom and a halogenated hydrocarbon group. 1 type selected from the group consisting of That is, by making at least one of R ^a , R ^b , R ^c and R ^d a bulky substituent more than a methyl group, the porphyrin orientation is twisted and circular dichroism appears.

  Examples of the hydrocarbon group having 1 to 8 carbon atoms include linear or branched alkyl groups such as methyl group, ethyl group, propyl group, n-butyl group, and isobutyl group. The number of carbon atoms of the hydrocarbon group is preferably about 1 to 4, more preferably about 1 to 2.

  Examples of the oxygen-containing substituent include an ester group and a carboxyalkyl group. Examples of the ester group include a methyl ester group and an ethyl ester group. A carboxymethyl group etc. can be illustrated as a carboxyalkyl group.

  Examples of the nitrogen-containing substituent include an amino group, an amide group, and a 2-aminoethyl group.

  Examples of the halogen atom include Cl, Br, F and the like.

  Examples of the halogenated hydrocarbon group include a methyl chloride group, an ethyl chloride group, a propyl chloride group, and a butyl chloride group.

In the above chemical formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different, 1 type selected from the group which consists of a hydrogen atom, a hydrocarbon group, a halogen atom, and a halogenated hydrocarbon group is shown.

Examples of the hydrocarbon group include linear or branched alkyl groups such as a methyl group, an ethyl group, a propyl group, an n-butyl group, and an isobutyl group. The carbon number of the hydrocarbon group represented by R ^{1 to} R ¹² is not particularly limited, but is usually about 1 to 10, preferably about 1 to 4, and more preferably about 1 to 2.

The halogen atom and the halogenated hydrocarbon group are the same as the halogen atom and the halogenated hydrocarbon group exemplified in the description of R ^{a to} R ^d above.

  In particular, the porphyrin dimer used in the method of the present invention is preferably a compound of the following chemical formula (II) (hereinafter sometimes simply referred to as “compound 2”).

  The reagent used in the method of the present invention may contain an additive component within a range in which a desired effect can be obtained.

  The porphyrin dimer represented by the chemical formula (I) can be produced by a known method. Known methods are described in VV Borovkov, JM Lintuluoto and Y. Inoue, Helv. Chem. Acta, 1999, 82, 919-934, VV Borovkov, JM Lintuluoto and Y. Inoue, Synlett, 1998, 768, etc. Can be exemplified.

Organic Acid The target organic acid in the method of the present invention is (i) capable of coordinating to a porphyrin dimer, and a group capable of coordinating to a porphyrin dimer and an asymmetric carbon are directly bonded. Or (ii) can coordinate to the porphyrin dimer, and one carbon atom is interposed between the coordinateable group and the asymmetric carbon.

  The organic acid that can be coordinated to the porphyrin dimer is not particularly limited, but an organic acid having a relatively high acidity is preferable. Examples of such organic acids include acidic groups such as carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, phosphinic acid groups, boronic acid groups, and sulfonic acid groups as groups capable of coordinating with the porphyrin dimer. The compound which has is mentioned. In particular, according to the method of the present invention, the absolute configuration of the sulfonic acid or carboxylic acid can be determined more suitably.

In the method of the present invention, the organic acid may form a salt.
The salt of the organic acid can be obtained, for example, by reacting the organic acid with a basic compound. The basic compound is not particularly limited, and examples thereof include water-soluble inorganic salts such as sodium hydroxide, potassium hydroxide, lithium hydroxide and ammonia, amines such as n-propylamine, monoethanolamine and triethanolamine, and monomethyl. Water-soluble organic salts such as quaternary ammonium hydroxides such as triethylammonium hydroxide and trimethylbenzol ammonium hydroxide or guanidine hydroxides may be mentioned.

The organic acid preferably has an electron withdrawing group at the α-position and / or β-position carbon of the acidic group from the viewpoint of easy coordination to the compound 1.
Examples of the electron withdrawing group include a hydroxyl group, a methoxy group, an acetoxy group, a fluoro group, a chloro group, a bromo group, an iodo group, a nitro group, and a cyano group.

  Examples of the organic acid in which the group capable of coordinating with the porphyrin dimer and the asymmetric carbon are directly bonded include 2-chloro-3-methylbutanoic acid, 2-hydroxybutanoic acid, 2-acetoxypropionic acid, 2- Examples include methoxyphenylacetic acid, mandelic acid, and 3-phenyllactic acid.

  Examples of the organic acid in which one carbon atom is interposed between the coordinable group and the asymmetric carbon include 10-camphorsulfonic acid.

Sample Solution In the method of the present invention, the sample solution used for CD spectrophotometric analysis contains the reagent and an organic acid. The preparation of the sample solution is not particularly limited. For example, the sample solution can be prepared by a method of dissolving the porphyrin dimer, organic acid or the like, which is an active ingredient, in a solvent.

As the solvent used when preparing the sample solution, a solvent that does not coordinate with the porphyrin dimer is preferable. Solvents that do not coordinate with the porphyrin dimer include chloroform (CHCl ₃ ), methane dichloride (CH ₂ Cl ₂ ), ethane dichloride (CH ₂ ClCH ₂ Cl), ethane tetrachloride (CHCl ₂ CHCl ₂ ), tetra Examples thereof include halogenated aliphatic hydrocarbons such as carbon chloride (CCl ₄ ); aliphatic hydrocarbons such as hexane and heptane.

  The concentration of the porphyrin dimer in the sample solution is not limited. The lower limits of these concentrations are not particularly limited as long as the first or second cotton effect can be detected, and can be appropriately set according to the type of porphyrin dimer used, the type of organic acid, the type of solvent, and the like. The upper limit of the concentration of the organic acid and the upper limit of the concentration of the porphyrin dimer in the sample solution is, for example, that the ellipticity value of the first or second cotton effect is about twice or more the noise level in the CD spectrum (for example, 1 mdeg or more It is preferable to set the ellipticity of the first or second cotton effect to be as large as possible when the voltage of the photomultiplier tube is within −700 kV, and the ellipticity of the first or second cotton effect is 10 mdeg to It is more preferable to set so as to be about 50 mdeg.

The concentration of the organic acid in the sample solution may be appropriately set according to the type of the chiral compound, etc., but is usually about 10 ⁻⁴ mol / l or more, preferably about 10 ⁻⁴ to 10 ⁻¹ mol / l. More preferably, it is about 10 ⁻⁴ to 10 ⁻³ mol / l. When the concentration of the organic acid is less than 10 ⁻⁴ mol / l, the cotton effect may not be sufficiently detected.

The concentration of the porphyrin dimer in the sample solution can be appropriately set according to the type of the organic acid and the like, but is usually about 10 ⁻⁷ mol / l or more, preferably about 10 ⁻⁶ mol / l or more. It is. The upper limit of the concentration of the porphyrin dimer in the sample solution can be appropriately set according to the type of the organic acid and the like, but is usually about 5 × 10 ⁻⁵ mol / l or less, preferably 5 × 10 ⁻ It is about ⁶ mol / l or less.

Determination Method of Absolute Configuration In the method of the present invention, CD spectrophotometric analysis is performed on the sample solution, and the asymmetric carbon of the organic acid (hereinafter sometimes simply referred to as “organic acid”) from the sign of the Cotton effect. This is a method for determining the absolute configuration.

  In the method of the present invention, when performing CD spectrophotometric analysis, it is not necessary to perform a complicated operation such as cooling the sample solution, but by setting the temperature of the sample solution to about −30 to 30 ° C., CD spectrophotometric analysis can be performed with high sensitivity.

  The CD spectrum of the sample solution shows two peaks (one maximum and one minimum). Hereinafter, the peak on the longer wavelength side may be referred to as “first cotton effect”, and the peak on the shorter wavelength side may be referred to as “second cotton effect”. The sign of each peak may be positive or negative, and the sign of the first cotton effect is different from the sign of the second cotton effect.

  Table 1 shows the absolute configuration of various organic acids and the sign of each cotton effect in the sample solution.

  As is clear from Table 1, in the case of (R) -10-camphorsulfonic acid, the sign of the first cotton effect is negative (minus), and the sign of the second cotton effect is positive (plus). On the other hand, in the case of (S) -10-camphorsulfonic acid, the sign of the first cotton effect is positive (plus), and the sign of the second cotton effect is negative (minus).

  For the determination of the absolute arrangement, any sign of the first cotton effect and the second cotton effect may be used, but the first cotton effect can be used more suitably because it is easier to detect.

  Further, as is apparent from Table 1, a certain correspondence relationship is established between the configuration of the organic acid and the sign of each cotton effect. That is, when the sign of the first cotton effect is positive, the absolute configuration of the organic acid is (S). On the other hand, when the sign of the first cotton effect is negative, the absolute configuration of the organic acid is (R). That is, the absolute configuration of the asymmetric carbon of the unknown organic acid can be determined by using this correlation and the sign of the Cotton effect obtained from the CD spectrum of the unknown organic acid.

In Table 1, the _B‖ transition is a transition in the case where the moments of two porphyrin rings whose absorption bands are the B band (Soley band) are in the direction in which the porphyrin rings are combined. The _BＢ transition is a transition when the moments are in a direction perpendicular to the direction in which the porphyrin rings are bonded together. In FIG. 2, the direction of the moment in the achiral compound 1 before the organic acid is coordinated is shown by a solid line.

On the other hand, in compound 1 coordinated with an organic acid, as shown by a dotted line in FIG. 2, the moment of one ring is higher in both cases of _B‖ transition and _BＢ transition than in achiral compound 1. The direction is slightly deviated from the direction of the other moment.

  Hereinafter, in the present invention, a mechanism for generating the cotton effect will be described. When a solution containing Compound 1 and an organic acid is prepared, the organic acid is considered to coordinate to the nitrogen atom of Compound 1. The organic acid may coordinate to any of the nitrogen atoms in the two porphyrin rings. When only one of the porphyrin rings has a bulky substituent more than the methyl group, the organic acid is considered to coordinate with the nitrogen atom of the other porphyrin ring from the porphyrin ring having such a substituent. . With such coordination of organic acid, the porphyrin dimer shows a conformational change from the syn type to the anti type, and at the same time, asymmetry is induced in the anti type conformer, as shown in FIG. Shows good circular dichroism.

  The mechanism of asymmetric induction is explained by the twisting of porphyrin rings as shown in FIG. More than the largest substituent (R) bonded to the α or β carbon (α carbon in FIG. 3) of the chiral compound that is the ligand and the methyl group bonded to the porphyrin ring to which the organic acid is not coordinated Due to steric hindrance between the bulky substituent (Et: ethyl group in FIG. 3), the orientation of porphyrin is twisted, and circular dichroism based on exciton interaction (exciton interaction) between porphyrins. It can be understood that it appears.

  According to the CD exciton chirality method, when two interacting electron transition moments are arranged clockwise from the front toward the back, positive chirality is created, and when counterclockwise is arranged, negative chirality is created. (Harada, N., Nakanishi, K., "Circular Dichroic Spectroscopy-Excition coupling in Organic Stereochemistry, University Science Books, Mill Valley, 1983., Nakanishi, K., Berova, N.," In Circular Dichroism; Principles and Applications ", Woody, R., Ed, VCH Publishers; New York, 1994; pp361-398).

  For example, when an organic acid having an absolute configuration of (S) is coordinated to compound 1, it is twisted clockwise from the near side toward the far side (see FIG. 3), so the sign of the first cotton effect is “positive”. . On the other hand, when the organic acid having the absolute configuration R is coordinated to the compound 1, it is twisted counterclockwise from the near side toward the far side, so that the sign of the first cotton effect is “negative”.

  In the method of the present invention, a sample solution containing an organic acid, compound 1 and the like is analyzed using CD spectrophotometry. That is, in the method of the present invention, the absolute configuration of the organic acid can be determined by the sign of the Cotton effect of the CD spectrum obtained by coordinating the organic acid to be measured with Compound 1. According to the method of the present invention, it is possible to determine the absolute configuration directly without inducing a special modifying group in the organic acid.

  Hereinafter, the present invention will be described in more detail with reference to examples of the present invention. However, the present invention is not limited to the following examples.

A JASCO-J-720WI spectropolarimeter was used for CD spectrum measurement.
Example 1
In a 3 ml cell (optical path length: 1 cm), about 10 ⁻⁶ mol / l of Compound 2 and about 10 ⁻¹ mol / l of 3-phenyllactic acid in CH ₂ Cl ₂ were prepared. A 500 nm CD spectrum was measured. The results are shown in FIG.

  As apparent from FIG. 1 and Table 1, since the sign of the first cotton effect on the longer wave side is negative, the absolute configuration of the asymmetric carbon of 3-phenyllactic acid is (R).

Example 2
A CD spectrum was measured in the same manner as in Example 1 except that 2-hydroxybutanoic acid was used instead of 3-phenyllactic acid and measurement was performed at -40 ° C, -20 ° C, 0 ° C, and 22 ° C. The results are shown in FIG.

  As is clear from FIG. 4 and Table 1 above, since the sign of the first cotton effect on the longer wave side is negative, the absolute configuration of the asymmetric carbon of 2-hydroxybutanoic acid is (S).

  Further, as is apparent from FIG. 4, it can be seen that the sensitivity of the peak of the CD spectrum is improved at a lower temperature.

Comparative Example 1
As an absolute configuration determination reagent, the following zinc porphyrin dimer (about 10 ⁻⁶ mol / l) was used in place of Compound 2 and measurement was performed at −40 ° C., −20 ° C., 0 ° C. and 22 ° C. In the same manner as in Example 1, the CD spectrum of the sample solution containing 3-phenyllactic acid was measured.

  However, when the measurement temperatures were −20 ° C., 0 ° C., and 22 ° C., the cotton effect could not be detected. Further, when the measurement temperature was −40 ° C., the cotton effect was slightly detected, but the absolute configuration of 3-phenyllactic acid could not be determined.

It is a figure which shows the measurement result of the circular dichroic spectrum obtained in Example 1. FIG. It is a figure which shows the direction of the moment regarding B band which is the maximum absorption band of a porphyrin dimer. A porphyrin dimer is schematically shown with a porphyrin ring as an ellipse and a cross-linked carbon chain as a straight line. Two ellipses (porphyrin rings) do not exist on the same plane, but are located in the front and back. It is a figure which shows the twist of porphyrin rings produced by a steric hindrance. It is a figure which shows the measurement result of the circular dichroic spectrum obtained in Example 2. FIG.

Claims (3)

A method for determining the absolute configuration of an organic acid having an asymmetric carbon,
(1) The following chemical formula (I)

[Wherein, R ^a , R ^b , R ^c and R ^d are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an oxygen-containing substituent, a nitrogen-containing substituent, a halogen atom and a halogen atom. 1 type selected from the group consisting of activated hydrocarbon groups, provided that at least one of R ^a , R ^b , R ^c and R ^d is a hydrocarbon group having 1 to 8 carbon atoms, oxygen-containing substitution 1 type selected from the group consisting of a group, a nitrogen-containing substituent, a halogen atom and a halogenated hydrocarbon group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different and each represents one selected from the group consisting of a hydrogen atom, a hydrocarbon group, a halogen atom and a halogenated hydrocarbon group. ]
A reagent containing as an active ingredient a porphyrin dimer represented by:
(2) (i) an organic acid that can be coordinated to a porphyrin dimer and in which a group that can be coordinated to the porphyrin dimer and an asymmetric carbon are directly bonded, or (ii) a porphyrin dimer A circular dichroism spectrophotometric analysis is performed on a sample solution including an organic acid that can be coordinated to a body and has a carbon atom intervening between the coordinateable group and the asymmetric carbon. And determining the absolute configuration of the asymmetric carbon of the organic acid from the sign of the cotton effect. The method according to claim 1, wherein the organic acid is a sulfonic acid or a carboxylic acid. The method of Claim 1 or 2 which performs a circular dichroism spectrophotometric analysis in -30-30 degreeC.

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