JP3138015B2 - Separating agents for liquid chromatography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new use of a specific asymmetric Schiff base copper complex. The above-mentioned new use is a use as a chirality discriminating agent, that is, an enantiomeric mixture of a compound having chirality such as β-amino alcohol in liquid chromatography.
(For example, a racemic body).

[0002]

2. Description of the Related Art Separating agents for optical resolution comprising an amino acid derivative coated on a silica gel carrier for reversed phase are already known.
[(1) Chromatographia, Vol. 13, p. 677 (1980), (2) JP-A-58-96062
No., (3) JP-A-64-26523]. The above (1) and
The separating agent described in (2) uses an N-alkyl derivative of proline or hydroxyproline as an amino acid to be supported, and the separating agent described in (3) uses serine as an amino acid to be supported. , Alanine or N, N-dialkyl derivatives of norvaline.

[0003] Also, a separating agent for optical resolution comprising a reversed phase silica gel carrier coated with an oxyacid derivative is already known [(4) Journal of Liquid Chromatography No. 9]. 551 (1986)]. The separating agent described in the above (4) uses L-tartaric acid mono-n-octylamide as the oxyacid to be supported. It is also known that an asymmetric Schiff base copper complex (the same as used in the present invention) is applied to the inner surface of a gas chromatography tube and used [(5) Analytical Chemistry Vol. 29, p. 156]. .

[0004]

The above (1), (2) and
The packing using the amino acid derivative of (3) exhibits excellent resolving power for specific amino acids, but there is no report confirming the resolving power for β-amino alcohols. the above
The filler using L-tartaric acid mono-n-octylamide of (4) not only exhibits excellent separation ability for amino acids, but also exhibits some β-amino alcohols.
Although it exhibits a slight separation ability, it has the disadvantage that the carrier compound must always be contained in the mobile phase in order for the carrier compound to flow out of the column. In addition,
The technique of gas chromatography (5) is completely different from liquid chromatography.

The present invention is particularly suitable for use in the optical resolution of β-aminoalcohols, and is stable, easy to use, and has excellent separation ability without the above-mentioned drawbacks. It is intended to provide a separating agent for liquid chromatography having the same.

[0006]

That is, the present invention provides a compound of the general formula (I)

Embedded image [Wherein, * represents an irregular carbon. R ₁ represents a lower alkyl group, a monocyclic aryl lower alkyl group, a lower alkoxy-substituted monocyclic aryl lower alkyl group or a lower cycloalkyl lower alkyl group. R ₂ represents a monocyclic aryl group having a lower alkoxy or a monocyclic aryl lower alkoxy as a substituent. X ₁ and X ₂ each represent a hydrogen atom or a halogen atom, or together represent a group —CH ₂ —CH ＝ CH—CH ₂ —], and form a complex of a Schiff base with copper (II). It is intended to provide a separating agent for liquid chromatography, which is coated on a reversed phase carrier.

The above complex (hereinafter referred to as an asymmetric copper complex) has the formula
(Ia)

Embedded image [Tetrahedron / Letters]
(Tetrahedron Letters) 1975 (No. 21) No. 17
07-1710, and JP-B-57-14661
No.], formula (Ib)

Embedded image ["Synthetic Organic Chemistry"
Vol. 43, No. 12, page 32 and "Catalyst" Vol. 19, No. 3
27-page, especially page 329].

The terms used in the above general formula (I) are explained as follows. As "lower alkyl", alkyl having 1-8, preferably 1-6, carbon atoms, for example, methyl,
Ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, hexyl and the like. "Lower alkoxy" represents a group of the formula (lower alkyl) -O-. "Monocyclic aryl" includes phenyl unsubstituted or substituted with lower alkyl. “Aryl” includes bicyclic aryl such as naphthyl and biphenylyl, in addition to the above monocyclic aryl. "Lower cycloalkyl" includes cycloalkyl having 3-6 carbon atoms, for example, cyclopentyl, cyclohexyl and the like. "Halogen" includes fluorine, chlorine, bromine and iodine. When X ₁ and X ₂ together represent the group —CH ₂ —CH ＝ CH—CH ₂ —
This group together with the benzene ring to which X ₁ and X ₂ are bonded form a naphthalene nucleus.

The above-mentioned asymmetric copper complex can be produced by the combination of the corresponding asymmetric amino alcohol, salicylaldehyde derivative and an appropriate cupric salt (for example, JP-B-53-43955). The asymmetric primary amine used for producing the asymmetric copper complex is represented by the following general formula (II).

Embedded image (In the formula, *, R ₁ and R ₂ have the same meaning as described above.)
As R ₂ of the asymmetric primary amine represented by the general formula (II), a phenyl group having a substituent at the 2-position is preferable. Examples of such R ₂ include 2-methoxyphenyl,
Examples include 2-isopropoxyphenyl, 2-benzyloxyphenyl, 2-methoxy-5-methylphenyl, 2-isopropoxy-5-methylphenyl, 2-benzyloxy-5-methylphenyl, and the like. The general formula (I
As the asymmetric primary amine represented by I), the following compounds can be specifically exemplified. That is, 2
-Amino-1,1-di (2-methoxyphenyl) -3-phenylpropanol-1,2-amino-1,1-di (2-
(Methoxy-5-methylphenyl) -3-phenylpropanol-1,2-amino-1,1-di (2-ethoxyphenyl) -3-phenylpropanol-1,2-amino-
1,1-di (2-isopropoxyphenyl) -3-phenylpropanol-1, 2-amino-1,1-di (2-butoxyphenyl) -3-phenylpropanol-1,2-
Amino-1,1-di (2-benzyloxyphenyl) -3
-Phenylpropanol-1,2-amino-1,1-di
(2-butoxy-5-t-butylphenyl) -3-phenylpropanol-1 and the like. These asymmetric primary amines represented by the general formula (II) can be produced by reacting an optically active α-amic acid ester with a Grignard reagent (for example, JP-B-51-13133).

The salicylaldehyde derivative used for the production of the Schiff base represented by the general formula (I) is represented by the following general formula (I)
II).

Embedded image (In the formula, X ₁ and X ₂ have the same meanings as described above.) Examples of the salicylaldehyde derivative represented by the general formula (III) include the following compounds.
That is, salicylaldehyde, 3,5-dibromosalicylaldehyde, 5-chlorosalicylaldehyde, 2-
And hydroxy-1-naphthaldehyde.

The Schiff base (I) obtained from the compounds (II) and (III) by a conventional method is reacted with a copper (II) salt (for example, acetate) and treated with an alkali to obtain an asymmetric copper complex. The asymmetric copper complex is to be used in the form of a pure optical isomer or an isomer mixture in which one optical isomer predominates.

[0012]

[Use] When a compound represented by the formula (I) is brought into contact with a compound having chirality, such as β-amino alcohol, a physicochemically different qualitatively or qualitatively to two optical isomers is obtained. Since they interact, they can be used in liquid chromatography as chirality discriminating agents. The simplest application in this application is the separation of two optical isomers or the removal of one optical isomer using a separating agent comprising an asymmetric copper complex bound to a solid.

As the separating agent, a solid support whose surface is coated with an irregular copper complex is convenient. Granules of a reversed phase carrier are used as the solid carrier. As such a carrier, any carrier having a hydrophobic surface can be used regardless of whether it is an inorganic or organic carrier. Preferable examples are silica gel surface-treated with an alkylsilane having 3 to 18 carbon atoms, porous glass surface-treated with an alkylsilane having an alkyl group having 3 to 18 carbon atoms, and styrene and acrylic. Examples thereof include hydrophobic polymer gels and the like. The shape of the carrier may be crushed or spherical, and it may be porous or non-porous.
It is preferably a spherical porous carrier having a particle size of m. In this case, by using a porous carrier having a large surface area, the coating amount of the irregular copper complex can be increased, and the covering amount can be adjusted by controlling the surface area of the carrier. The pore diameter of the porous carrier is 10
Preferably, the thickness is 1000 Å and the surface area is in the range of 1 to 1000 m ² . A method for coating a solid support with an asymmetric copper complex is described in the literature [Chromatia (Chrome).
atographia), Vol. 13, p. 667 (1980)], and directly introducing an aqueous solution of a hydrophilic solvent such as alcohol or tetrahydrofuran in which an asymmetric copper complex is dissolved into a column for liquid chromatography packed with a reversed phase carrier,
A method of coating is convenient, and a method of mixing a solution of the reversed phase carrier and the asymmetric copper complex and distilling off the solvent under reduced pressure can also be used.

The carrier coated with the asymmetric copper complex is subjected to optical resolution of a racemate by a liquid chromatography method. This can be performed, for example, as follows. A column made of glass, stainless steel, titanium or the like having an appropriate length, for example, a length of 1 to 100 cm, is densely packed with a separating agent, and a liquid feed pump and a sample injector are provided at the inlet side of the column; A detector such as an ultraviolet detector or an optical rotation detector and a fraction collector if necessary are connected to the outlet side. Separation can be performed by a usual method. That is, after injecting a racemate, an eluent is sent by a liquid sending pump, and the injected racemate is developed and divided in a column. Suitable eluents include aqueous solutions of copper salts, for example aqueous solutions of 0.1-10 mM copper sulfate or copper acetate. In this case, 0 to 30% by volume of an organic solvent miscible with water such as methanol or acetonitrile.
When added to the eluent, favorable results are easily obtained. Generally, as the amount of the organic solvent added increases, the retention time of the racemate tends to decrease. It is extremely preferable to keep the pH of the eluent constant to obtain a chromatogram with good reproducibility. The eluate eluted from the column is introduced into a detector such as an ultraviolet detector, and each of the separated enantiomers is detected by, for example, absorbance at 254 nm, and the chromatogram is recorded by a recorder.

[0015]

The separating agent of the present invention can separate various optical isomer mixtures, particularly optical isomers of aromatic amino alcohols, by a chromatography method. As for the aromatic amino alcohols, a wide range of amino alcohols and β-amino acids, α-oxycarboxylic acids including phenylglycinol, phenylalaninol, etc., which were difficult, as well as norepinephrine, norephedrine, etc. Optical resolution of various racemates coordinated with the above-mentioned metal ions such as .beta.-aminocarboxylic acid and 1,2-diamine is possible. Moreover, the separating agent of the present invention has an advantage that it is easy to produce and has excellent durability.

[0016]

EXAMPLES The present invention will be described below with reference to examples.
The examples do not limit the invention. Example 1 (+) (R) -N-salicylidene-2-amino-1,1-di
Copper complex of (2-butoxy-5-t-butylphenyl) -3-phenylpropanol-1 (in the general formula (I), R ₁ =
Benzyl, R ₂ = 2-butoxy-5-t-butylphenyl, X ₁ = X ₂ = Schiff base complex corresponding to hydrogen) 0.
30 g was coated on a reversed phase carrier by the following method. Average particle size 5 μm surface treated with octadecylsilane
First, a mixed solution consisting of 50% by volume of tetrahydrofuran and 50% by volume of water was passed through a stainless steel column (inner diameter 4.6, length 150 mm) packed with 1.5 g of porous silica gel having the following formula: Next, 0.06% of the copper complex of (+) (R) -N-salicylidene-2-amino-1,1-di (2-butoxy-5-t-butylphenyl) -3-phenylpropanol-1 was added. 50% by volume of tetrahydrofuran and 50 of water
After 0.5 liter of a mixed solution of 0.5% by volume was passed through the column at a rate of 0.6 ml / min, 60 ml of a 1 mmol / l copper sulfate aqueous solution was passed at a rate of 1.0 ml / min.

In the column coated as described above, 0.
Inject 1 to 5 μl of each racemic aqueous solution of amino alcohol and amino acid of 0.1 to 0.05% by weight,
An aqueous solution of mmol / l copper sulfate was fed at a flow rate of 0.2 to 1.0 ml / min to develop a racemate. Tables 1 and 2 show examples of the results obtained by resolving racemic forms of various amino alcohols and amino acids in this manner. The measurement conditions were as follows. Temperature: room temperature Eluent flow rate: 0.2-1.0 ml / min Detector: UV absorption spectrometer (wavelength: 254 nm) In this table, the retention time means that each of the enantiomers after the racemate was injected into the column. It means the time required for separation and elution from the column, that is, the time for which each enantiomer is retained in the column. The separation coefficient α representing the optical resolution of the separating agent is calculated by the following equation. α = (t ₂ −t ₀ ) / (t ₁ −t ₀ ) t ₁ : retention time of the less strongly adsorbed enantiomer t ₂ : retention time of the more strongly adsorbed enantiomer t ₀ : dead volume of the column When α = 1, a retention time corresponding to the separation factor indicates that there is no optical resolution, and that the optical resolution increases as the difference from 1 increases.

[0018]

[Table 1]

[0019]

[Table 2]

FIG. 1 shows the (±) -phenylalaninol separating agent. In FIG. 1, the peak number (1) is (−) −
Phenylalaninol, peak number (2) was (+)-
Phenylalaninol. FIG. 2 shows an example of DL-tyrosine separation. In Figure 2, the peak number
(3) is D-tyrosine, and peak number (4) is L-tyrosine. Thus, it can be seen that in the column packed with the separating agent of the present invention, the aromatic amino alcohol and the aromatic amino acid can be completely and extremely efficiently separated.

[Brief description of the drawings]

FIG. 1 is a graph showing an elution curve when (±) -phenylalaninol is resolved using the separating agent of the present invention.

FIG. 2 is a graph showing an elution curve when DL-tyrosine is separated using the separating agent of the present invention.

[Explanation of symbols]

 1 (-)-phenylalaninol 2 (+)-phenylalaninol 3 D-tyrosine 4 L-tyrosine

──────────────────────────────────────────────────続 き Continuing on the front page (51) Int.Cl. ⁷ Identification symbol FI G01N 30/48 G01N 30/48 W (72) Inventor Reiko Nakamura 3-1-1, Nittacho, Niihama-shi, Ehime Prefecture Sumika Co., Ltd. Analysis Center Niihama Sales Office (72) Inventor Fumiko Seiko 3-1-1 135 Kasuganaka, Konohana-ku, Osaka-shi, Japan Sumika Chemical Analysis Service Co., Ltd. (56) References JP-A-56-20521 (JP, A) JP-A-52-85101 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 229/02 C07B 57/00 C07B 63/00 C07C 227/34 CA (STN)

Claims (1)

(57) [Claims] 1. An aqueous solution of a mixture of optical isomers of an aromatic amino alcohol or an amino acid is represented by the general formula (I): Wherein * represents an asymmetric carbon, R ₁ represents a lower alkyl group, a monocyclic aryl lower alkyl group, a lower alkoxy-substituted monocyclic aryl lower alkyl group or a lower cycloalkyl lower alkyl group, and R ₂ represents X ₁ and X ₂ each independently represent a hydrogen atom or a halogen atom, or together form a group —CH ₂ —CH = CH-CH ₂ - represent. The complex of Schiff base and copper (II) is contacted with a separating agent coated on a reversed-phase solid support, and the separating agent is treated with an eluent to give the aromatic amino alcohol or amino acid A method for directly separating a mixture of optical isomers of aromatic amino alcohol or amino acid by liquid chromatography, wherein at least one of the optical isomers is collected.