JPH0113725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel tritylated β-cyclodextrin and a method for producing the same. More specifically, the present invention can be used as a reagent for stabilizing unstable substances, making poorly water-soluble substances easily soluble, separating products from reaction systems, separating isomers, etc., or as an artificial material having enzyme-like catalytic activity. 6-o-trityl-β-cyclodextrin and 6,6′-di-o-trityl-β-cyclodextrin, which are intermediates for producing polysubstituted modified cyclodextrins useful as enzymes, and their tritylated β- The present invention relates to a method for producing cyclodextrin.

PRIOR ART Cyclodextrin is a cyclic oligosaccharide in which six or more D-glucose units are α-1,4-linked, and among them, one with six glucose units is called α-cyclodextrin, and one with seven glucose units is called α-cyclodextrin. It is known that eight β-cyclodextrins are industrially useful as γ-cyclodextrins. These cyclodextrins have a cylindrical cavity within their molecules, and have the property of forming clathrate compounds by incorporating various substances into the molecule. Utilizing its ability to form compounds, it is used in the food and pharmaceutical industries to stabilize unstable substances and to make poorly water-soluble substances more easily soluble.

In addition, in order to form an inclusion compound, the shape and size of the molecule of the clathrate must fit into the cavity of the cyclodextrin, and the degree of compatibility determines the relationship between the clathrate and the cyclodextrin. Because there is a difference in the affinity that acts between the molecules, it is possible to separate and divide various substances by utilizing this difference. Furthermore, since cyclodextrin has enzyme-like catalytic activity, it is possible to separate and divide various substances. In recent years, research has been actively conducted to develop this enzyme as an artificial enzyme.
[Accounts of Chemical Research (Acc.Chem.Res.) Volume 15, Page 66 (1982
Year)〕.

By the way, although cyclodextrin is a compound with such excellent functions, there are limits to its functionality when used alone, so many modified cyclodextrins with higher functionality have been proposed ["Tetra Tetrahedron, Volume 39, Page 1417 (1983)
2007)]. For example, as a model for the hydrolase α-chymotrypsin, only one of the primary hydroxyl groups of cyclodextrin is converted to tosyl (p-toluenesulfonyl), then iodinated, and then
Compounds substituted with histamine [Journal of American Chemical Society (J.
Am.Chem.Soc.) Volume 97, Page 4432 (1975
2002)] used a compound in which the tosyl group was substituted with a pyridylthiol derivative as a model for aminotransferase [J.Am.Chem.Soc. No. 102].
Vol., p. 421 (1980)] have been proposed.

These modified cyclodextrins have only one primary hydroxyl group substituted, but since enzymes generally have two or more different catalytic functional groups, they are useful for molecular design of artificial enzymes. teeth,
It is necessary to introduce functional groups at multiple defined positions on the cyclodextrin. The cap method is known as one of the methods [“Tetrahydron
Tetrahedron Lett., page 1527 (1977)]. However, in this method,
Two of the primary hydroxyl groups of cyclodextrin can be substituted with the same amino group or thiol group,
It is difficult to introduce other functional groups and different substituents.

On the other hand, recently, cyclodextrins in which some or all of the hydroxyl groups are methylated have been produced, and their physical properties are attracting attention. Fully methylated cyclodextrin dissolves well in both water and organic solvents, and the ring structure cannot be immobilized due to the formation of intramolecular hydrogen bonds, and furthermore, due to the steric hindrance of the methyl group, it has a significantly distorted conformation. As a result, the selectivity of inclusion for optical isomers increases [Journal of Pharmaceutical Dynamics (J.Pharm.Dyn.), Volume 5, Page 1027 (1982)] . In addition, the physical properties and functionality of partially modified methylated cyclodextrins are also attracting attention. This partially modified methylated cyclodextrin can be obtained by, for example, protecting one or two of the primary hydroxyl groups of cyclodextrin in advance, methylating all remaining hydroxyl groups, and then removing the protecting groups. can be obtained as having one or two hydroxyl groups.

By substituting one or two hydroxyl groups of the partially methylated cyclodextrin thus obtained with other functional groups, an enzyme model compound having one or two catalytic groups can be obtained. Furthermore, other polysubstituted modified cyclodextrins can be obtained by performing various alkylations and acylations in addition to methylation using the cyclodextrin in which one or two hydroxyl groups are protected. .

In this way, compounds in which one or two of the primary hydroxyl groups of cyclodextrin are protected are extremely useful as intermediates for producing polysubstituted modified cyclodextrins.

By the way, the tritylated (triphenylmethyl) group has been known for a long time as a protecting group for the primary hydroxyl group of sugars, and mono(6-o-trityl)-α-cyclodextrin has already been produced [“Carbon Hydrate Research (Carbohydr.
Res.) Volume 18, Page 29 (1971)]. However, β-cyclodextrin, which is said to be the cheapest and most useful product, has tritylated four of its seven primary hydroxyl groups [Chem.
Ber.) Vol. 102, p. 494 (1969)], and other tritylated forms have not yet been obtained. This is probably because it was difficult to isolate and purify a specific derivative from a mixture of β-cyclodextrin derivatives having different numbers of trityl groups produced by the reaction.

Problems to be Solved by the Invention The first object of the present invention is to create a novel 6-o-trityl-β-cyclodextrin and a 6,6'-di- The object of the present invention is to provide o-trityl-β-cyclodextrin, and a second object is to provide a method for producing each of these tritylated β-cyclodextrins with good yield and high purity.

Means for solving the problem As a result of extensive research, the present inventors found that by reacting trityl halide with β-cyclodextrin in pyridine, one trityl group and two
It is easy to obtain a mixture mainly consisting of a compound having trityl groups, and adducts of compounds having one and two trityl groups with cyclohexane have different solubility in aqueous solvents, so by taking advantage of this property, We have discovered that the above object can be achieved, and based on this knowledge, we have completed the present invention.

That is, the present invention provides the general formula (In the formula, n is 1 or 2) In tritylated β-cyclodextrin and pyridine, 1 to 4 moles of trityl halide are reacted per mole of β-cyclodextrin to form a tritylated β-cyclodextrin. After obtaining a mixture of dextrins, the formula The 6,6′-di-o-trityl-β-cyclodextrin represented by the formula The present invention provides a method for producing tritylated β-cyclodextrin, which comprises separating 6-o-trityl-β-cyclodextrin and 6-o-trityl-β-cyclodextrin, respectively. In the case where n in the above general formula is 2, it has not yet been confirmed to which glucose unit the trityl group is bonded.

In the present invention, it is desirable to use sufficiently dried β-cyclodextrin, and if necessary, dry it in advance at room temperature to 100% using a vacuum dryer or the like.
Use after drying at a temperature of °C. Also,
Trityl halide is β-cyclodextrin 1
It is used in a range of 1 to 4 moles per mole.
If this amount is less than 1 mole, there will be a large amount of unreacted β-cyclodextrin, making it impractical, whereas if it exceeds 4 moles, a large amount of trityl groups having three or more trityl groups will be produced, which is not preferable.

Suitable tritylation of β-cyclodextrin in the present invention can be carried out, for example, by dissolving 1 part by weight of β-cyclodextrin in 20 to 100 parts by weight of dehydrated pyridine, and then adding a predetermined amount of trityl to 1 mole of β-cyclodextrin. This is carried out by adding a halide such as trityl chloride and heating at a temperature of 60 to 100°C with stirring. At this time, in order to prevent the influence of moisture in the air, the reaction may be carried out in a nitrogen stream if necessary. Also, the reaction time is
Although it depends on the ratio of trityl chloride to β-cyclodextrin and the reaction temperature, generally 10
About 3 minutes to 3 hours is sufficient.

Next, to explain one example of a suitable post-treatment of the reaction-completed liquid, first add the same mole of sodium hydrogen carbonate as the trityl chloride used to the reaction-completed liquid, then add approximately the same volume of ethanol as pyridine, and reduce the pressure. Concentrate. After repeating this operation several times, the concentrated residue is vacuum dried, then thoroughly washed with methylene chloride, acetone, etc., and then dried. Through this operation, a white solid containing β-cyclodextrin having one or two trityl groups as the main component, unreacted β-cyclodextrin, and a small amount of a β-cyclodextrin derivative having three or more trityl groups is produced. A mixture of:

The composition of this mixture depends on the reaction conditions;
For example, when 2 to 4 moles of trityl halide are used for 1 mole of β-cyclodextrin, most of the β-cyclodextrin reacts, resulting in a mixture containing monotritylated products and ditritylated products as main components, and trityl halide. When about 1 mole of halide is used, a mixture containing a monotritylated product and unreacted β-cyclodextrin as main components and a small amount of a ditritylated product is obtained.

Next, an aqueous solvent is added to 1 part by weight of this mixture.
After adding 30 to 50 parts by weight and heating to a temperature of 80 to 90°C to dissolve as much of the mixture as possible, the mixture is cooled to around room temperature. Water is preferably used as the aqueous solvent. Next, add cyclohexane per 1 part by weight of the mixture to the liquid containing the mixture and the aqueous solvent.
After adding 0.3 to 1 part by weight and stirring for 3 to 5 hours to precipitate the ditritylated product and the cyclohexane adduct of unreacted β-cyclodextrin, the mixture is filtered and dried. When 2 to 4 moles of trityl halide are used per mole of β-cyclodextrin, the ditritylated form is the main component, and if necessary, the melting point 6 represented by the above formula () with high purity having a temperature of 296 to 298 °C (decomposition),
6'-di-o-trityl-β-cyclodextrin is easily obtained.

The residual liquid after removing the cyclohexane adduct of the ditritylated product contains the monotritylated product and a small amount of β.
- Contains cyclodextrin, and after concentrating this residual liquid to dryness, 1 part by weight of the dried product is mixed with a mixed solvent of alcohol and water, such as a mixed solvent of butanol, ethanol, and water (volume ratio of 3 :
2:1) Add 30 to 50 parts by weight, heat to 45 to 55°C to dissolve as much of the dried product as possible, and filter. After repeating this extraction operation several times and concentrating the filtrates together to dryness, recrystallization from a 70 to 90% by weight aqueous n-propanol solution can be performed to obtain a melting point
High purity 6-o-trityl-β-cyclodextrin represented by the above formula () having a temperature of 255 to 260°C (decomposition) can be easily obtained.

When 2 to 4 moles of trityl halide are reacted with 1 mole of β-cyclodextrin, 6,6′-di-o-trityl-β
-60-70% cyclodextrin. 6-o-trityl-β-cyclodextrin is obtained with a yield of 20-30%.

Effects of the Invention According to the present invention, novel compounds 6-o-trityl-β-cyclodextrin and 6,6'-di-o
-Trityl-β-cyclodextrin can be obtained very easily and in high purity. These tritylated β-
Cyclodextrins are useful as reagents for stabilizing unstable substances, making poorly water-soluble substances easily soluble, separating products from reaction systems, separating isomers, and as artificial enzymes with enzyme-like catalytic activity. It is suitably used as an intermediate for polysubstituted modified cyclodextrin.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples.

Example 1 2.27 g (2.0 mmol) of β-cyclodextrin dried overnight with phosphorus pentoxide in vacuum drying
Dissolve 1.40 g (5.0 mmol) of trityl chloride in 40 ml of dehydrated pyridine, keep stirring at 70-80°C, and react for 2 hours. After cooling, 400 mg (4.8 mmol) of sodium hydrogen carbonate and 20 ml of ethanol were added to the reaction mixture and concentrated under reduced pressure. After adding 20 ml of ethanol and concentrating under reduced pressure twice, the mixture was dried in vacuo to obtain a white solid. Ta.

This white solid was washed twice with 20 ml of methylene chloride and then with 20 ml of acetone, and then dried to obtain 3.68 g of a reaction mixture, which was then added with 140 ml of distilled water.
Add and heat to 90℃ to dissolve as much as possible, then cool to below 50℃ and add 2ml of cyclohexane.
was added and stirred vigorously to precipitate a white precipitate. After further stirring for 3 hours, this precipitate was collected by filtration, washed with 10 ml of cold water, and dried to obtain 2.55 g of a white solid.

This white solid was dissolved in an 80% n-propanol aqueous solution for 30 minutes.
By recrystallizing from ml, 6,6′-di-o
2.10 g (65% yield) of -trityl-β-cyclodextrin was obtained. Add this to 80% n-
By recrystallizing from an aqueous propanol solution, a product having the following physical properties was obtained.

Melting point: 296-298℃ (decomposition) TLC: Rf0.54 (n-butanol/ethanol/
Water 3:2:1, silica gel) UV: ε ^259nm _nax 1290 (ethanol/water 1:1) Elemental analysis value (as C ₈₀ H ₉₈ O ₃₅ ) C H Actual value (%) 59.07 6.15 Calculated value (%) 59.32 6.10 Meanwhile, 50 ml of ethanol was added to the filtrate from which the precipitate of the cyclohexane adduct had been removed, and the mixture was carefully concentrated to dryness to obtain 1.27 g of a white solid. Then, heat to about 50°C to dissolve as much as possible, filter, and wash the residue with 10 ml of the mixed solvent. Add 40ml of mixed solvent to the residue again and perform extraction step 3.
Repeat times.

The filtrate thus obtained was combined and concentrated to dryness to obtain 0.96 g of a white solid.
When recrystallized from 8 ml of n-propanol aqueous solution, 6-o-trityl-β-cyclodextrin
0.72g (yield 26%) was obtained. Furthermore, when this product was recrystallized from an 80% aqueous n-propanol solution, a product having the following physical properties was obtained.

Melting point: 255-260℃ (decomposition) TLC: Rf0.42 (n-butanol/ethanol/
Water 3:2:1, silica gel) UV: ε ^260nm _nax 630 (ethanol/water 1:1) Elemental analysis value (as C ₆₁ H ₈₄ O ₃₅ ) C H Actual value (%) 52.92 6.08 Calculated value (%) 53.19 6.15 Example 2 2.27 g of dried β-cyclodextrin
(2.0mmol) and trityl chloride 620mg
(2.2 mmol) was dissolved in 40 ml of dehydrated pyridine, kept at 70-80°C with stirring, and reacted for 3 hours.
After cooling, the reaction mixture was then added sodium bicarbonate.
After adding 180 mg and 20 ml of ethanol and concentrating under reduced pressure, adding 20 ml of ethanol and concentrating under reduced pressure twice, the mixture was dried in vacuo to obtain a white solid.

This white solid was washed twice with 20 ml of methylene chloride and then with 20 ml of acetone, and then dried to obtain 2.96 g of a reaction mixture. Next, add 140 ml of distilled water to this
ml of cyclohexane, heated to 90°C until almost dissolved, cooled to below 50°C, and added 2 ml of cyclohexane.
ml was added and stirred vigorously to precipitate a white precipitate. After further stirring for 3 hours, the precipitate was filtered, 50 ml of ethanol was added to the filtrate, and the mixture was concentrated to dryness to obtain 1.15 g of a white solid.

This white solid was mixed with butanol as in Example 1.
3 with 40ml of mixed solvent of ethanol:water=3:2:1
Extract twice and concentrate the extract to dryness to produce 0.92g of white solid.
I got it. When this product is recrystallized from 8 ml of 80% n-propanol aqueous solution, 6-o-trityl-β
- 0.70 g (yield 25%) of cyclodextrin was obtained.

Claims (1)

[Claims] 1. General formula (n in the formula is 1 or 2) A tritylated β-cyclodextrin represented by: 2. In pyridine, 1 to 4 moles of trityl halide are reacted per mole of β-cyclodextrin to obtain a mixture of tritylated β-cyclodextrin, and then using cyclohexane and an aqueous solvent, the formula The 6,6′-di-o-trityl-β-cyclodextrin represented by the formula 1. A method for producing tritylated β-cyclodextrin, which comprises separating 6-o-trityl-β-cyclodextrin. 3. The method according to claim 2, wherein the aqueous solvent is water. 4 The mixed solvent of alcohol and water is butanol,
3. The method according to claim 2, wherein the mixed solvent is ethanol and water.