HK1088002B

HK1088002B - Process for resolving 2,4-diamino-3,6-dihydro-1,3,5-triazines, useful for the treatment of disorders associated with insulin resistance syndrome

Info

Publication number: HK1088002B
Application number: HK06108146.0A
Authority: HK
Inventors: Gérard Moinet; Daniel Cravo; Thierry Passemar
Original assignee: Poxel Sas
Priority date: 2003-04-10
Filing date: 2004-04-06
Publication date: 2009-01-02

Description

Resolution method of 2, 4-diamino-3, 6-dihydro-1, 3, 5-triazines useful in the treatment of disorders associated with insulin resistance syndrome

The present invention relates to a process for the resolution of amine compounds derived from dihydro-1, 3, 5-triazines from the corresponding racemic mixture.

The dihydrotriazine family of compounds have beneficial pharmacological properties.

There are many reports in the literature on dihydro-1, 3, 5-triazine compounds. Thus, patent application WO01/53276 describes dihydrotriazine compounds of the formula:

where R1 may be hydrogen, they are dihydrofolate reductase inhibitors, and in particular have antimalarial activity.

Abstract JP 48064088 describes dihydrotriazine compounds of the formula:

wherein R1 may be hydrogen. These compounds are described herein as having activity in lowering blood glucose levels.

Abstract JP 54014986 describes dihydrotriazine compounds of the formula:

wherein R may be hydrogen, are compounds having anti-diabetic activity.

Patent US 3287366 describes dihydrotriazine compounds of the formula:

where R3 can be hydrogen, they are useful as herbicides.

Patent application WO 01/55122 describes dihydrotriazine compounds of the formula:

wherein R5 may be hydrogen. These compounds are useful for treating disorders associated with insulin resistance syndrome.

When the above R groups represent hydrogen, these compounds all carry an asymmetric carbon atom. The corresponding enantiomer is not disclosed. Likewise, the processes for their preparation have not been described or mentioned in the literature published to date.

It is well known that the biological activity of enantiomers of racemic compounds can vary widely depending on the two enantiomers. Thus, in general, one enantiomer is more active and thus more suitable as an active ingredient of a medicament.

The use of this enantiomer is more advantageous than the use of the racemate. In particular, this makes it possible to reduce the dose of active ingredient in the drug, since the identified enantiomer has a higher activity. And the dosage can be reduced to relieve adverse side effects. Therefore, it is desirable that the active ingredient contains only the pure enantiomer having the greatest desired biological activity.

There are many ways to separate a racemic mixture into its two pure enantiomers. For more information on this, see in particular the book "chiral technology" (1993) by r.a. sheldon published by Dekker.

Examples of such methods that may be mentioned include:

separation method based on differences in physical properties

Separation methods based on the use of biotechnological methods (whole cells, enzymes, etc.)

Separation methods based on the use of chromatography

Separation processes based on the formation of diastereoisomers (salts, addition of chiral centers).

It is therefore an object of the present invention to propose a process for the separation of a racemic mixture of amino derivatives of dihydro-1, 3, 5-triazines as defined above.

In the separation of racemic mixtures, it is necessary to have available a method for monitoring the enantiomeric excess. The standard method is to monitor the change in optical rotation of the diastereomeric salt or enantiomer. However, this method is relatively unsuitable for compounds having a low optical rotation.

The use of chiral HPLC is also a common method. It has been found that this approach does not make it possible to achieve exploitable results.

We have surprisingly found that the use of chiral HPLC in the supercritical phase allows us to obtain two enantiomers. This technology has recently been developed in the fields of analysis and preparation. The basic principle of this technique is described, for example, in the book "Chromatographies en phase liquide et hypercriticique [ liquid phase and supercritical phase chromatography ] published by Masson in Paris in 1991.

The process of the invention thus allows us to obtain pure enantiomers easily and economically.

More specifically, the separation process comprises the step of asymmetric transformation of a racemic compound of the following structural formula (I):

wherein R1, R2, R3 and R4 are independently selected from the group consisting of:

-H；

-alkyl (C1-C20) optionally substituted by halogen, alkyl (C1-C5), alkoxy (C1-C5) or cycloalkyl (C3-C8);

-alkenyl (C2-C20), optionally substituted by halogen, alkyl (C1-C5) or alkoxy (C1-C5);

-alkynyl (C2-C20) optionally substituted by halogen, alkyl (C1-C5) or alkoxy (C1-C5);

-cycloalkyl (C3-C8), optionally substituted with alkyl (C1-C5) or alkoxy (C1-C5);

-heterocycloalkyl (C3-C8) containing one or more heteroatoms chosen from N, O and S, optionally substituted by alkyl (C1-C5) or alkoxy (C1-C5);

-aryl (C6-C14) alkyl (C1-C20) optionally substituted by amino, hydroxyl, mercapto (thio), halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

-aryl (C6-C14) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

-heteroaryl (C1-C13) containing one or more heteroatoms selected from N, O and S, optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

r1 and R2, or R3 and R4, may form an n-membered ring (n is between 3 and 8) with the nitrogen atom, which may optionally contain one or more heteroatoms selected from N, O and S, and may be substituted with one of the following groups: amino, hydroxyl, sulfydryl, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

r6 is selected from the following groups:

-alkyl (C1-C20) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

-alkenyl (C2-C20) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

-alkynyl (C2-C20) optionally substituted by amino, hydroxy, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxy, carboxymethyl or carboxyethyl;

-cycloalkyl (C3-C8) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

-heterocycloalkyl (C3-C8) containing one or more heteroatoms chosen from N, O and S, optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

-aryl (C6-C14) alkyl (C1-C5) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl.

In a preferred group of compounds of formula (I), R3 and R4 represent hydrogen atoms. Another group of preferred compounds of formula (I) is that R1 and R2 represent C1 to C3 alkyl, preferably methyl.

Particularly preferred compounds of formula (I) are:

(+) -2-amino-3, 6-dihydro-4-dimethylamino-6-methyl-1, 3, 5-triazine hydrochloride;

(-) -2-amino-3, 6-dihydro-4-dimethylamino-6-methyl-1, 3, 5-triazine hydrochloride;

(+) -2-amino-6-cyclohexyl-3, 6-dihydro-4-dimethylamino-1, 3, 5-triazine hydrochloride;

(-) -2-amino-6-cyclohexyl-3, 6-dihydro-4-dimethylamino-1, 3, 5-triazine hydrochloride.

The method of the invention generally comprises the steps of:

-preparing a diastereomeric salt of a compound of formula (I);

-purifying the obtained diastereomer;

liberating the pure enantiomer from the purified diastereomer.

The resolution is carried out in the presence of a chiral reagent.

Since the target compound is an amine, it is preferred to use a chiral acid as the chiral reagent for resolving the racemic mixture.

The diastereomeric salt thus obtained is subjected to a purification step and the enantiomer is released from the purified salt.

Examples of chiral acids that can be used include: (+) -D-di-O-benzoyl-tartaric acid, (-) -L-di-O-benzoyl tartaric acid, (-) -di-O, O '-p-tolyl-L-tartaric acid, (+) -di-O, O' -p-tolyl-D-tartaric acid, R (+) -malic acid, S- (-) -malic acid, (+) -camphanoic acid, (-) -camphanoic acid, R (-) -1, 1 '-binaphthyl-2, 2' -diyl hydrogen phosphate, S (+) -1, 1 '-binaphthyl-2, 2' -diyl hydrogen phosphate, (+) -camphoric acid, (-) -camphoric acid, L-toluic acid, L, S (+) -2-phenylpropionic acid, R (-) -2-phenylpropionic acid, D (-) -mandelic acid, L (+) -mandelic acid, D-tartaric acid, L-tartaric acid, or mixtures thereof.

The chiral acid is preferably selected from the group consisting of (-) -di-O, O '-p-tolyl-L-tartaric acid, (+) -di-O, O' -p-tolyl-D-tartaric acid, R (-) -1, 1 '-binaphthyl-2, 2' -diyl hydrogen phosphate, S (+) -1, 1 '-binaphthyl-2, 2' -diyl hydrogen phosphate, D-tartaric acid and L-tartaric acid.

The formation of diastereomeric salts can be carried out in a polar solvent or in a mixed solvent containing at least one polar solvent.

The formation of diastereomeric salts can be carried out at a temperature in the range of-10 ℃ to the reflux temperature of the solvent or solvent mixture.

Once the diastereomeric salts are separated, and more generally at any time, the enantiomeric excess can be checked by means of supercritical chiral HPLC.

In the supercritical phase HPLC technique, the mobile phase filtered through the stationary phase contains a gas in a supercritical state.

Carbon dioxide is preferred because of its low cost, high volatility and non-hazardous properties to the atmosphere. The advantage of this technique is therefore that it is not harmful to both the staff and the environment, especially in plants where large amounts of mobile phase mixture may be used. Moreover, its high volatility makes it easy to isolate the purified compound after the purification is completed.

The HPLC mobile phase therefore usually contains from 60% to 100% by volume of CO₂. The remaining portion is prepared using a solvent or a mixture of solvents. Polar solvents are preferred for adjusting the polarity of the mobile phase. These solvents may be selected from, for example, alcohols, halogenated hydrocarbons, ethers, and nitriles.

The HPLC mobile phase may also contain acidic or basic polarity modifiers. Examples of acidic polarity modifiers that may be mentioned include optionally halogenated carboxylic acids such as trifluoroacetic acid, acetic acid and formic acid. Basic polarity modifiers that may be mentioned include alkyl amines such as diethylamine and triethylamine. The HPLC mobile phase typically contains 0.01% to 2% by volume of an acidic or basic polarity modifier.

The HPLC stationary phase (column) is selected from enantioselective stationary phases. Columns based on oligosaccharides or polysaccharides are particularly suitable. Such columns are commercially available, in particular from DaicelAnd of Chiralsep corporation

The column temperature and the column pressure are adjusted so that the gas contained in the mobile phase is in a supercritical state. The pressure is generally chosen to be in the range of from 80 to 350 bar, preferably from 100 to 200 bar, most preferably from 120 to 170 bar.

The temperature is preferably adjusted between 30 and 50 ℃.

The amount of diastereomer salt solution injected depends on the column used, in particular the size of the column. The process is carried out in particular in a volume of between 5 and 50. mu.l.

The flow rate of the mobile phase is usually adjusted to 1 to 3.5 ml/min, preferably 2 to 3 ml/min.

Once the diastereomeric salt is isolated, it can be purified to the desired diastereomeric purity by, for example, recrystallization from a suitable solvent or mixture of solvents.

The purified diastereomeric salt is then dissociated in an acidic or basic medium in a suitable solvent or mixture of solvents. This allows the recovery of the desired enantiomer from a racemic mixture of the compound of formula (I).

If the enantiomer obtained from the racemic mixture of the compound of formula (I) is in the base form, it can be salified with a pharmaceutically acceptable organic or inorganic acid.

The enantiomers of the compounds of formula (I) in which R1, R2, R3, R4 and R6 have the meanings indicated above are also subjects of the present invention.

In particular, the enantiomers can be used for preparing medicaments for treating diabetes, insulin resistance syndrome related diseases or diabetes related diseases such as atherosclerosis and micro-and macroangiopathy. Finally, the enantiomers of the invention can also be used for the preparation of a medicament for the treatment of malaria.

The following illustrations may help illustrate the invention and they represent:

FIG. 1: supercritical phase chiral HPLC chromatogram of the starting racemic compound in example 1, retention time of the (+) enantiomer was 8.77 min and retention time of the (-) enantiomer was 10.48 min;

FIG. 2: supercritical phase chiral HPLC chromatogram of the (+) enantiomer after purification in example 1;

FIG. 3: supercritical phase chiral HPLC chromatogram of the starting racemic compound in example 2, retention time of the (+) enantiomer was 11.74 min and retention time of the (-) enantiomer was 13.84 min;

FIG. 4: supercritical phase chiral HPLC chromatogram of purified (-) enantiomer of example 2;

the present invention is described in further detail by the following examples, which are not intended to limit the scope of the present invention.

Example 1

Preparation of (+) -2-amino-3, 6-dihydro-4-dimethylamino-6-methyl-1, 3, 5-triazine hydrochloride

A solution of 348.5g of (-) -di-O, O' -p-tolyl-L-tartaric acid in 1L of methanol was added to a solution of 200g of (. + -.) -2-amino-3, 6-dihydro-4-dimethylamino-6-methyl-1, 3, 5-triazine (chromatogram of FIG. 1) in 1L of methanol. After stirring for 5 hours, the precipitate formed is filtered off with suction (33% yield, 70% ee, determined by supercritical chiral HPLC using a "supercritical liquid chromatography system" model SF3 from Gilson under the following conditions:

-pressure: 150 bar

-flow rate: 2.5 ml/min

-a stationary phase:W1-T (available from Chiralsep)

-a mobile phase: 69.8% CO₂30% methanol and 0.2% diethylamine

Column temperature: 40 deg.C

UV detection at 240nm

-injection volume: 20 μ l

-concentration: 1mg/ml

The composition of the mobile phase is expressed as the volume composition at column operating conditions.

The diastereomeric salts were recrystallized from a DMF/95 ° ethanol mixture (1/1) (38% yield, 94% ee).

The concentrated salt was suspended in a water/ethyl acetate mixture (1/1) and the whole was cooled to 0 ℃. One equivalent of 2M hydrochloric acid was added without exceeding the temperature by 5 ℃.

Vigorous stirring was continued for 15 hours. The organic phase is recovered to reuse (-) -di-O, O' -p-tolyl-L-tartaric acid. The aqueous phase was concentrated and the resulting solid was recrystallized from 95 ℃ ethanol to give 20g of a white powder (> 99% ee, 10% overall yield,. alpha._D ^26℃(C＝5，H₂O) +2.10) (fig. 2).

Example 2

Preparation of (-) -2-amino-6-cyclohexyl-3, 6-dihydro-4-dimethylamino-1, 3, 5-triazine hydrochloride

A solution of 150g (. + -.) -2-amino-6-cyclohexyl-3, 6-dihydro-4-dimethyl-amino-1, 3, 5-triazine (FIG. 3) in 1.5l ethyl acetate and 750ml 95 ℃ ethanol was kept at 80 ℃ until complete dissolution. A solution of 100.9g D (-) -tartaric acid in 750ml 95 ° ethanol was added, heating continued for 1 hour and then cooling to room temperature. The precipitate formed was suction filtered off (30% yield, 80.6% ee, determined by supercritical chiral HPLC using a "supercritical liquid chromatography system" model SF3 from Gilson under the following conditions:

-pressure: 150 bar

-flow rate: 2.5 ml/min

-a stationary phase:W1-T (available from Daicel)

-a mobile phase: 91% CO₂8% methanol and 1% diethylamine

Column temperature: 40 deg.C

UV detection at 240nm

-injection volume: 20 μ l

-concentration: 1mg/ml

The composition of the mobile phase is given as the volume composition at the column operating conditions.

The solid was dissolved in water and isobutanol was added. Sodium hydroxide is added with vigorous stirring, after a few minutes the organic phase is separated, dried over sodium sulfate and concentrated. The concentrate is dissolved in acetonitrile, cooled to 0 ℃ and added after dissolving one equivalent of hydrogen chloride in isopropanol, the temperature not exceeding 5 ℃. After a few hours, the precipitate formed is filtered off with suction and recrystallized from ethanol (24g, > 99% ee, 16% overall yield,. alpha._D ^24℃(C＝5，H₂O) — 109.40) (fig. 4).

Claims

1. A process for resolving a racemic compound of the following formula (I):

wherein:

r1, R2, R3 and R4 are independently selected from the group consisting of:

-H；

-aryl (C6-C14) alkyl (C1-C20) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

r1 and R2, or R3 and R4, may form an n-membered ring (n is between 3 and 8) with the nitrogen atom, which may optionally contain one or more heteroatoms selected from N, O and S, and may be substituted with one or more of the following: amino, hydroxyl, sulfydryl, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

r6 is selected from the following groups:

-aryl (C6-C14) alkyl (C1-C5) optionally substituted by amino, hydroxyl, mercapto, halogen, alkyl (C1-C5), alkoxy (C1-C5), alkylthio (C1-C5), alkylamino (C1-C5), aryl (C6-C14) oxy, aryl (C6-C14) alkoxy (C1-C5), cyano, trifluoromethyl, carboxyl, carboxymethyl or carboxyethyl;

the method comprises the following steps:

a) reacting a racemic compound of formula (I) with a chiral acid (-) -di-O, O' -p-tolyl-L-tartaric acid;

b) thereby forming the corresponding diastereomeric salt;

c) purifying the obtained diastereomeric salt;

d) the pure enantiomer of formula (I) is released from the purified diastereomeric salt in the form of a pharmaceutically acceptable salt.

2. The method of claim 1, wherein in the compound of formula (I), R1 and R2 represent CH₃。

3. The method of claim 1 or 2, wherein in the compound of formula (I), R3 and R4 represent H.

4. The method of claim 1, wherein the enantiomeric excess is detected by supercritical chiral HPLC.

5. The process of claim 4, wherein the HPLC mobile phase contains 60% to 100% by volume of CO₂。

6. The process of claim 4 or 5, wherein the HPLC mobile phase further comprises a polar solvent.

7. The process of claim 4 or 5, wherein the HPLC mobile phase further comprises an acidic or basic polarity modifier.

8. The process of claim 4 or 5, wherein the HPLC stationary phase is based on an oligosaccharide or a polysaccharide.

9. The process of claim 1 or 2, wherein the release of the enantiomer from the diastereomeric salt is accomplished by dissociation of the diastereomeric salt in an acidic or basic medium in a suitable solvent.

10. The process of claim 1 or 2, wherein the release of the enantiomer from the diastereomeric salt is accomplished by dissociation of the diastereomeric salt in an acidic or basic medium in a suitable mixed solvent.

11. The process of claim 1 or 2, wherein the enantiomerically pure compound of formula (I) is selected from the following compounds: