JPH0672163B2 - Process for producing aminated cyclodextrin polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a copolymer of C-6-monoamino-β-cyclodextrin and β-cyclodextrin (hereinafter referred to as aminated CD polymer). is there. More specifically, a copolymer of C-6-N-alkyldihydronicotinamide-β-cyclodextrin and β-cyclodextrin, which is expected to have a function as an artificial enzyme (hereinafter referred to as N-alkyldihydronicotinamide CD polymer). The present invention relates to a process for producing an aminated CD polymer which is useful as an intermediate for the production of

[Conventional technology]

A CD polymer in which cyclodextrin (hereinafter referred to as CD) is three-dimensionally crosslinked with a crosslinking agent is already known. Examples of crosslinking agents include epichlorohydrin and diisocyanate.

All of these polymers have a specific inclusion function that CD has. The advantage of CD polymer lies in its insolubility
The molecular recognition ability of the reaction substrate of can be repeatedly extracted continuously.

For example, Nosakura et al. Reported the asymmetric resolution of mandelic acid, which is well suited for steric cyclodextrin cavities by using epichlorohydrin cross-linked CD as a packing material for liquid chromatography (J.Polym.Sci.Poly. Chem. Ed., 16 , 189 (197
8)).

In addition, Hirai et al. Obtained 4-hydroxybenzoic acid specifically from phenol in the same manner as cyclodextrin alone by adding a similar epichlorohydrin-crosslinked CD polymer to the reaction system. Volume 44, 49 (19
86)).

However, in the previous reports, the polymerized CD was not chemically modified except that the crosslinking agent was bonded. Therefore, most of the conventional CD polymers are used only for separation / purification, and those involved in the reaction are used only for reaction control that controls the orientation to the benzene ring and are very limited. Was there.

On the other hand, there are many reports of chemically modified cyclodextrins, which are CD-cylindrical molecules that chemically modify the hydroxyl groups around them. Since it has both a molecular recognition ability of CD and a reaction activity, it is promising as a selective reaction catalyst.

The present inventors stereo-specifically perform monotosylation at the C-6 position of the pyranose ring of β-cyclodextrin (hereinafter referred to as β-CD) in an alkaline aqueous solution, and further maintain the modified position while maintaining the amino group. Was introduced, and nicotinamidated CD was synthesized by amide bond with this amino group. The nicotinamide group is one of the vitamin B group, is a coenzyme of alcohol dehydratase in the living body, and is an important molecule involved in the reduction of ketones. The active form of this nicotinamide group,
That is, the conversion to the dihydronicotinamide form is enzymatically performed in vivo, but the present inventors have used sodium dithionite (Na ₂ S ₂ O ₄ ) to chemically react dihydronicotine. As a model reaction of the electron transfer system, which is an important metabolic pathway for energy acquisition in vivo, for conversion to amidated cyclodextrin, reduction reaction for various dye molecules is performed, and the reaction between the dye's three-dimensional structure and reaction rate is performed. I found the correlation of. This reduction reaction is a model experiment for elucidating the metabolic pathway of the living body and is also a very useful reaction as an industrial method for selective alcohol production.

However, in order for the chemically modified CD to work effectively, it has to be added to the reaction system at a high concentration, it is difficult to extract the product from the reaction system, and the reacted nicotinamide cyclodextrin is added to the reaction system. There was a problem in using it on an industrial level such that it was difficult to remove it from the plant and reuse it again.

[Problems to be solved by the invention]

In addition to the ability of the present invention to form an inclusion complex by the hydrophobic field of CD, the present invention
Pyranose Ring C-6 on Cyclodextrin of Polymer
An aminated CD polymer useful as an intermediate for producing a more practical highly functionalized cyclodextrin polymer having a chemical modification group such as asymmetric reduction reactivity by chemically modifying only one of the hydroxyl groups in the position It aims at providing the manufacturing method of.

[Means for solving problems]

That is, the present invention provides a C-6-monoamino-β-cyclodextrin and a β-cyclodextrin, which comprises reducing a copolymer containing C-6-monoazidinated-β-cyclodextrin and β-cyclodextrin as constituent components. The present invention relates to a method for producing a copolymer as a constituent component.

The production method of the present invention will be described below according to scheme 1.

(1) Production of Copolymer Copolymer Consisting of C-6-Monoazidinated-β-Cyclodextrin and β-Cyclodextrin as Polymerization of β-CD (β-Cyclodextrin) In the present invention, β-CD is, for example, A commercially available product obtained by reacting starch with a CD-forming enzyme can be used as it is.

The β-CD polymer can be obtained by polymerizing β-CD by a known method using epichlorohydrin as a crosslinking agent. During the reaction, the mixing amount of epichlorohydrin to β-CD was about 10 to epichlorohydrin relative to β-CD.
30 equivalents, preferably about 15 to 25 equivalents. If the amount of epichlorohydrin mixed during the reaction is less than 10 equivalents, a polymer in an aqueous solution having a small degree of crosslinking tends to be produced.

Also, the polymerization reaction is preferably carried out at a temperature of about 50 ° C. to 65 ° C. while stirring the reaction mixture. Relatively short time (for example, within about 2 hours) by setting the reaction temperature above 50 ℃
A polymer gel insoluble in water can be obtained. About 65
By setting the temperature to not higher than 0 ° C, a polymer without coloring can be obtained.

The β-CD polymer thus obtained has a crosslinked structure derived from epichlorohydrin in its structure —O—CH ₂ —C.
HOH-CH having ₂ -O-. The content of the crosslinked structure in the β-CD polymer varies depending on the reaction conditions, but is usually CD1.
To about 3-5.

Tosylation of β-CD Polymers β-CD polymers are tosylated by reaction with tocyclolide. The tosylation reaction is carried out by using an alkaline aqueous solution or pyridine as a solvent.

The method using an alkaline aqueous solution as a solvent can be carried out by dispersing the β-CD polymer in an alkaline aqueous solution having a pH of about 13, then adding tosyl chloride, and then reacting with stirring at room temperature for about 1 hour. The reaction introduces a tosyl group only at the C-6 position of β-CD of the β-CD polymer. Also, no more than two tosyl groups are introduced into the β-CD1 molecule. The introduction rate of the tosyl group at the C-6 position is about 10-40%, although it varies depending on the reaction conditions.

In addition, tosylation using pyridine as a solvent can be performed in substantially the same manner as in the case of using an alkaline aqueous solution.

The amount of tosyl chloride used is about 0.5 to 2 g per 1 g of β-CD polymer.

Azide of Tosylated β-CD Polymer The azylated β-CD polymer can be obtained by reacting the tosylated β-CD polymer with sodium azide. The reaction is carried out in a solvent such as DMF at about 10 to 40 ° C for about 10
It is carried out at -40 ° C for about 1 to 24 hours with stirring. The amount of sodium azide used is about 0.5 to 2 g per 1 g of β-CD polymer.

(2) C-6-amino-β-cyclodextrin and β
-Preparation of Copolymer Composed of Cyclodextrin (Amination-CD Polymer) Amination β-CD polymer can be obtained by reducing azide β-CD polymer with triphenylphosphine. The reduction reaction is carried out using dimethylformamide (DM
F) is used as solvent and is carried out in the presence of ammonia. The reaction is preferably carried out at room temperature with stirring for about 1-24 hours.

The amination of the azide β-CD polymer proceeds almost quantitatively.

The amount of triphenylphosphine used during the reaction is appropriately about 0.1 to 1 g per 1 g of the azide β-CD polymer.

The aminated β-CD polymer thus obtained can have various active groups introduced into its amino group. The β-CD polymer introduced into the active group can stereospecifically participate in various reactions. The activated dihydronicotinamide β-CD polymer will be described below.

(3) Production of activated dihydronicotinamide β-CD polymer Nicotinamidation of aminated β-CD polymer Nicotinamidated β-CD polymer comprises aminated β-CD polymer and nicotinic acid chloride in DMF-Et ₃ N It can be obtained by reacting in a solvent such as at 70 to 90 ° C. for about 1 to 24 hours with stirring.

The amount of nicotinic acid chloride used for the aminated β-CD polymer is about 0.1-1 g per 1 g of aminated β-CD polymer.
Is appropriate.

N-Methylation of Nicotinamidated β-CD Polymer N-methylnicotinamidated β-CD polymer is prepared by combining nicotinamide β-CD polymer and CH ₃ I in a solution such as DMF.
It is obtained by reacting with stirring at a temperature of about 50 to 70 ° C. for about 1 to 10 hours.

The amount of CH ₂ I used with respect to the nicotinamidated β-CD polymer is about 0.1 to 1 per 1 g of nicotinamidated β-CD polymer.
A value of g is appropriate.

Dihydrogenation of N-methylnicotinamide β-CD polymer N-methyldihydronicotinamide β-CD polymer (active dihydronicotinamide β-CD polymer)
Is an N-methylnicotinamide β-CD polymer and Na ₂ S ₂ O.
₄ and 1 in an aqueous Na ₂ CO ₃ solution at a temperature of about 10 to 40 ° C.
It is obtained by reacting with stirring for -24 hours.

The amount of Na ₂ S ₂ O ₄ used with respect to the N-methylnicotinamide β-CD polymer is appropriately about 0.3 to 1.5 g per 1 g of the N-methylnicotinamide β-CD polymer.
The Na ₂ CO ₃ concentration of the Na ₂ CO ₃ aqueous solution is preferably about 5 to 15% by weight.

The activated dihydronicotinamidated β-CD polymer thus obtained can be used, for example, for the stereoselective reduction of benzoylformic acid (BFA) to the chemically active mandelic acid.

Tosylated β-CD polymer, azide β-CD polymer, aminated β-CD polymer, nicotinamidated β described above
-CD polymer, N-methylnicotinamidated β-CD polymer and N-methyldihydronicotinamidated β-CD polymer are all novel substances.

The present invention will be described below with reference to examples and examples.

Reference Example 1 β-Cyclodextrin 50 g and sodium borohydride
0.07 g was kneaded with 60 ml of 50 w / v% sodium hydroxide solution while cooling with cold water. While maintaining the paste-like mixture at 50 ° C. with vigorous stirring, 40 ml of epichlorohydrin was added dropwise. After 2 hours, a gel-like polymer was obtained. The product was washed with acetone followed by water and dried. The yield was 50 g. 12 g of this polymer was suspended in sodium hydroxide at pH 13, 16 g of p-tolylsulfonyl chloride was added, and the mixture was stirred at room temperature for about 45 minutes. The reaction solution was neutralized with diluted hydrochloric acid and separated by filtration. The residue was washed with acetone to remove excess p-tolylsulfonyl chloride, and then vacuum dried. The yield was 10 g. As a result of elemental analysis, this gel-like polymer was found to be a cross-linked product of 5 molecules of epichlorohydrin reacted with 1 molecule of β-CD.
The ratio of tolylsulfonyl group (tosyl group) to cyclodextrin was 1: 3. Therefore the polymer is 33% C
-6-monotosyl-β-cyclodextrin and 60% β
Was constituted by cyclodextrin.

Reference Example 2 10 g of the polymer containing tosylated-β-cyclodextrin obtained in Reference Example 1 was suspended in dehydrated and purified DMF, 5 g of sodium azide was added, and the reaction system was kept at 80 ° C. and stirred for 7 hours.
The solvent was filtered off and washed well with acetone to obtain 13.4 g of an azide-β-cyclodextrin polymer. According to the infrared absorption spectrum, this product was confirmed to have an absorption characteristic of an azide compound at 2100 cm ^-1 .

Example The polymer obtained in Reference Example 2 was suspended again in DME, 3.5 g of triphenylphosphine was added, and the mixture was stirred at room temperature for 1 hr. Further, 3.5 ml of concentrated aqueous ammonia was added and the mixture was stirred for 12 hours. The solvent was filtered, the filter cake was washed with acetone and pure water repeatedly, and then dried. The yield was 10.2g. When this polymer was suspended in 0.1N hydrochloric acid and subjected to neutralization titration with a 0.1N sodium hydroxide solution, it was confirmed that it had an equivalence point at pH 9.9 and contained 209 μmol as an amino group in 1 g of dried gel. . 33% C-6 when converted to the number of molecules
It was composed of monoamino-β-cyclodextrin and 67% β-cyclodextrin.

Reference Example 3 2 g of the polymer containing amino-β-cyclodextrin obtained in Reference Example 2 was suspended in 25 ml of dehydrated and purified DMF, 1 ml of triethylamine and 1 g of nicotinic acid chloride were added, and the mixture was stirred at room temperature for 12 hours. The solvent was removed by filtration, the gel was washed with acetone and methanol, and then vacuum dried. The yield is 1.
It was 8 g. Resuspend this gel in dehydrated and purified DMF,
The N-position of the nicotinamide group was methylated with 0.3 g of methyl iodide. The obtained polymer gel was found to have about 33% N- (N-methylnicotinic acid) -amino-β- by elemental analysis.
It was composed of cyclodextrin and 67% β-cyclodextrin.

Reference Example 4 1 g of N- (N-methylnicotinic acid) -amino-β-cyclodextrin gel obtained in Reference Example 3 was dissolved in 10% aqueous sodium carbonate solution, and 0.7 g of sodium dithionite was added,
Stirred overnight at room temperature. Excess sodium dithionite was washed with water followed by methanol. The gel was mixed with an iodine solution and then redox titration was performed with sodium thiosulfate.
It was confirmed that it has a reducing power of μg equivalent and that it has a dihydronicotinamide group of 209 μmol / 1 g · dry gel considering that it is derived from a nicotinamide group.

Reference Example 5 N- (N-methyldihydronicotinic acid) -amino-β-cyclodextrin gel (N-Me-) obtained in Reference Example 4
NAH-β-CDE) 0.5 g (0.25 × 10 ^-5 mol) was suspended in a solvent, benzoylformic acid (BFA) was added as a substrate, and the reaction was carried out at 24 ° C for 60 hours under a nitrogen atmosphere in the dark. The gel was removed by and the filtrate was analyzed by liquid chromatography. As the reaction solvent, M / 40-phosphate, M / 20-Na ₂ B
_Four kinds of ₄ O ₇ , ethanol and acetonitrile were used respectively. The reaction yielded mandelic acid as the major product as shown below. However, as a solvent M / 20-
Benzoic acid and phenol were detected as other by-products when Na ₂ B ₄ O ₇ and ethanol were used.

The reaction conditions and the product analysis results are shown in Table 1.

In addition, it was revealed by analysis by high performance liquid chromatography that the production of mandelic acid by the reaction has asymmetric selectivity.

Claims (5)

[Claims] 1. A C-6-monoamino-β comprising reducing a copolymer containing C-6-monoazidinated-β-cyclodextrin and β-cyclodextrin as constituent components.
A method for producing a copolymer comprising cyclodextrin and β-cyclodextrin as a constituent. 2. The method according to claim 1, which comprises reducing a copolymer having C-6-monoazidinated-β-cyclodextrin and β-cyclodextrin as constituent components with triphenylphosphine. Law. 3. The production method according to claim 1 or 2, wherein the reduction reaction is carried out in the presence of ammonia. 4. The production method according to any one of claims (1) to (3), wherein the reduction reaction is carried out in dimethylformamide. 5. A copolymer comprising C-6-monoazidinated-β-cyclodextrin and β-cyclodextrin as constituents, tosylates a β-cyclodextrin polymer obtained by crosslinking β-cyclodextrin with epichlorohydrin, and then azide. Any one of claims (1) to (4), which is obtained by
The manufacturing method according to item.