WO2008123737A1

WO2008123737A1 - Docetaxel / mono propylene glycol clathrate and method for the preparation thereof

Info

Publication number: WO2008123737A1
Application number: PCT/KR2008/001979
Authority: WO
Inventors: Namdu Kim; Woo Seob Shin; Jaehyuk Jung; Gi Jeong Kim; Seung Hwan Cho; Eun Jung Lim; Young Ho Moon; Young-Kil Chang; Gwan Sun Lee
Original assignee: Hanmi Pharm. Co., Ltd.
Priority date: 2007-04-09
Filing date: 2008-04-08
Publication date: 2008-10-16
Also published as: KR100868116B1; KR20080091643A

Abstract

The present invention relates to a docetaxel / mono propylene glycol clathrate of formula (I) and a method for preparing same. The inventive docetaxel / mono propylene glycol clathrate having a low 7-epimer content and high stability can be advantageously used as an ingredient for the development of a therapeutic agent having anti-tumor and anti-leukemia activities.

Description

DOCETAXEL / MONO PROPYLENE GLYCOL CLATHRATE AND METHOD FOR THE PREPARATION THEREOF

FIELD OF THE INVENTION

The present invention relates to a docetaxel / mono propylene glycol clathrate and a method for the preparation thereof.

BACKGROUND OF THE INVENTION

Docetaxel, the compound of formula (II), is a chemotherapeutic agent having wide anti-tumor and anti-leukemia activities, which is approved for treating several cancer diseases such as breast cancer and ovarian cancer:

wherein, Ph is phenyl, Ac is acetyl, Bz is benzoyl, and Boc is t-butoxycarbonyl. Crystal forms of docetaxel which have been identified up to date include

(a) docetaxel trihydrate, (b) docetaxel hemihydrate and (c) anhydrous docetaxel, and X-ray diffraction scans thereof are shown in FIG. 1 {see U.S. Patent No. 5,723,635 and J. Phys., IV France 11, PrlO-221 (2001)), among which docetaxel trihydrate is the currently available form used in formulations.

U.S. Patent No. 5,723,635 discloses a method for the preparation of docetaxel trihydrate using a mixed solvent composed of methyl isobutyl ketone, acetone, and water. However, such a method requires the step of conducting a complex centrifugal partition chromatography process which is not suitable for an industrial purpose. Meanwhile, U.S. Patent No. 6,022,985 discloses a method for the preparation of docetaxel trihydrate by dissolving docetaxel in ethanol, mixing with water, subjecting the mixture to recrystallization at 50 °C, and drying the recrystallized docetaxel crystal in an oven under the condition of 38^°C, 80% relative humidity and 5.07 kPa for 48 h; and U.S. Patent No. 6,838,569 describes a method for the preparation of docetaxel trihydrate by dissolving docetaxel in acetonitrile, mixing with water, subjecting the mixture to recrystallization at 68 °C , and drying the isolated docetaxel crystal in an oven at 36 °C under a reduced pressure of 650 torr for 36 h. However, the docetaxel trihydrate products obtained by such methods have a high content, 0.4 to 0.8%, of the 7-epimer (4-acetoxy-2α-benzoyloxy-5-β, 20-epoxy-l,7α,10β-trihydroxy-9-oxo-tax-l l-en-13-α-yl(2R,3S)-3-t-butoxycarbo nylamino-2'-hydroxy-3-phenylpropionate), which requires an extra purification step for obtaining highly pure docetaxel having a 7-epimer content of 0.5% or less.

Accordingly, the present inventors have endeavored to develop an effective method for preparing highly pure docetaxel, and have unexpectedly found an efficient method for preparing highly stable and non-hygroscopic docetaxel / mono propylene glycol clathrate having a 7-epimer content of 0.1% or less.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide a docetaxel / mono propylene glycol clathrate having a 7-epimer content of 0.1% or less, which is highly stable and non-hygroscopic.

It is another object of the present invention to provide an efficient method for the preparation of said compound. In accordance with one aspect of the present invention, there is provided the docetaxel / mono propylene glycol clathrate of formula (I):

wherein, Ph is phenyl, Ac is acetyl, Bz is benzoyl, and Boc is t-butoxycarbonyl.

In accordance with another aspect of the present invention, there is provided a method for preparing the docetaxel / mono propylene glycol clathrate of formula (I), comprising the steps of dissolving docetaxel of formula (II) and propylene glycol in an organic solvent; adding to the resulting solution an anti-solvent to induce recrystallization; and harvesting the solid formed therein:

wherein, Ph, Ac, Bz and Boc have the same meanings as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of the invention, when taken in conjunction with the accompanying drawings, which respectively show: FIG. 1 : X-ray diffraction scans of (a) docetaxel trihydrate, (b) docetaxel hemihydrate and (c) anhydrous docetaxel;

FIG. 2: an X-ray diffraction scan of the docetaxel / mono propylene glycol clathrate prepared in Example 1 ; and FIG. 3: a nuclear magnetic resonance (NMR) spectrum of the docetaxel / mono propylene glycol clathrate prepared in Example 1.

DETAILED DESCRIPTION OF THE INVENTION

The compound of the present invention, docetaxel / mono propylene glycol clathrate of formula (I), contains propylene glycol entrapped by docetaxel, and has a docetaxel content of 90.0 to 92.5% by weight and a propylene glycol content of 7.6 to 9.6% by weight, based on the total weight thereof.

Docetaxel / mono propylene glycol clathrate of the present invention contains 0.1% or less of the 7-epimer (4-acetoxy-2α-benzoyloxy-5-β, 20-epoxy- 1 ,7α, 1 Oβ-trihydroxy-9-oxo-tax- 11 -en- 13-α-yl(2R,3 S)-3-t-butoxycarbo nylamino-2'-hydroxy-3-phenylpropionate), and it is non-hygroscopic and highly stable. Therefore, it can be advantageously used as an ingredient for the development of a therapeutic agent having anti-tumor and anti-leukemia activities.

The inventive compound, docetaxel / mono propylene glycol clathrate of formula (I) may be prepared by a method comprising the steps of dissolving docetaxel of formula (II) and propylene glycol in an organic solvent; adding to the resulting solution an anti-solvent to induce recrystallization; and harvesting the solid formed therein:

In the method of the present invention, docetaxel of formula (II) used as a starting material may be prepared by a method comprising the steps of 1) reacting the compound of formula (III) with 1-dimethoxymethylnaphthalene in an organic solvent in the presence of an acid catalyst to obtain the oxazolidine methyl ester derivative of formula (IV), followed by hydrolyzing the compound of formula (IV) in the presence of a base to obtain the oxazolidine acid derivative of formula (V); 2) coupling the compound of formula (V) with a protected 10-deacetylbaccatin III of formula (VI) in a solvent in the presence of a condensing agent to obtain the oxazolidine side-chain bearing taxane of formula (VII); 3) reacting the compound of formula (VII) with an acid in an organic solvent to obtain the docetaxel of formula (VIII) having protected 7,10-hydroxy groups; and 4) removing the 7,10-protecting groups from the compound of formula (VIII) to obtain docetaxel of formula (II), as shown in Reaction Scheme A. Reaction Scheme A

hydrolysis

deprotection

(VIII) (H)

The organic solvent used in the method of the present invention may be dichloromethane and ethyl acetate, which may be employed in an amount of 5 to 30 ml based on 1 g of docetaxel.

Further, the propylene glycol may be employed in an amount of 1 to 50 equivalents based on docetaxel.

In the present invention, the anti-solvent may be hexane and may be employed in an amount of 1 to 5 ml based on 1 ml of the organic solvent.

Further, the harvesting step may be conducted by filtering the recrystallized mixture to obtain a solid, and drying the solid in an oven at a temperature of 20 to 80 °C under a reduced pressure of 0.1 to 10 torr to remove the remaining solvent and anti-solvent from docetaxel / mono propylene glycol clathrate, e.g., to a level suitable for ICH (International Conference on Harmonization) guidelines providing acceptable amounts of residual solvents in pharmaceuticals .

The docetaxel / mono propylene glycol clathrate obtained in the method of the present invention exhibited to contain docetaxel in an amount of 90.0 to

92.5% by weight and propylene glycol in an amount of 7.6 to 9.6% by weight, based on the total weight of the clathrate, and also to have a 7-epimer content of

0.1% or less and a purity of at least 99.5% in the quantitative analysis.

Accordingly, the docetaxel / mono propylene glycol clathrate produced by the method of the present invention having low 7-epimer content and high stability as compared to docetaxel trihydrate produced by the conventional methods can be beneficially employed as an ingredient for the development of a therapeutic agent having anti-tumor and anti-leukemia activities.

The following Examples are given for the purpose of illustration only and are not intended to limit the scope of the invention.

Preparation Example

Step 1 : Preparation of (2R,4S,5R)-2-(l'-naphthyl)-3-t-butoxycarbonyl-4-phenyl -l,3-oxazolidine-5-carboxylic acid methyl ester (the compound of formula (IV))

295 g of (2R,3S)-N-t-butoxycarbonyl-4-phenylisoserine methyl ester, 6 g of pyridinium p-toluenesulfonate and 222 g of 1-dimethoxymethylnaphthalene were added to 6 L of toluene, and the mixture was refluxed for 1 h while removing 3 L of toluene therefrom. After cooling to room temperature, the reaction mixture was diluted with 3 L of ethyl acetate and neutralized with 1.5 L of saturated sodium bicarbonate. The organic layer was separated, washed with 1.5 L of saturated NaCl, and dried over anhydrous magnesium sulfate. The mixture was filtered and the filtrate was distilled under a reduced pressure to obtain 520 g of the title compound.

¹H NMR (300 MHz, CDCl₃): δ 8.36 (d, J = 8.4 Hz, IH), 7.89 (m, 2H, Ar), 7.42 (m, 1OH, Ar), 5.60 (s, IH), 4.58 (d, J = 2.7 Hz, IH), 3.11 (s, 3H), 1.06 (s, 9H).

Step 2: Preparation of (2R,4S,5R)-2-(l'-naρhthyl)-3-t-butoxycarbonyl-4-phenyl- 1 ,3-oxazolidine-5-carboxylic acid (the compound of formula (V))

The compound obtained in Step 1 was dissolved in 5 L of methanol, and

600 ml of 3 N lithium hydroxide was added dropwise thereto with stirring at

0 °C . After stirring for 2 h, the reaction mixture was distilled under a reduced pressure to remove 2.5 L of methanol, and 2.5 L of water was added dropwise thereto. The resulting aqueous layer was washed twice with 1 L of ethyl acetate/hexane (1/10, v/v) and neutralized by slowly adding 200 ml of 3 N HCl thereto while keeping the temperature at 0°C . The resulting mixture was extracted with 1 L of ethyl acetate, the separated organic layer was washed with

1 L of saturated NaCl, dried over anhydrous magnesium sulfate, filtered, and the filtrate was distilled under a reduced pressure to obtain 413 g of the title compound (yield: 98.5%). m.p. (melting point): 119 "C ; [α]_D ²³ = +56.9_O (c = 1, CHCl₃). 1H NMR (300 MHz, CDCl₃): δ 8.32 (d, J - 8.3 Hz, IH), 7.91 (m, 2H, Ar), 7.46 (m, 1OH, Ar), 5.60 (d, J = 3.1 Hz, IH), 4.62 (d, J = 3.1 Hz, IH), 1.04 (s, 9H).

Step 3: Preparation of (2^lR,4^tS,5¹R)-3^t-t-butoxycarbonyl-2^I-(l'"-naphthyl)-4¹- phenyl- 1 ',3'-oxazolidine-5'-carbonyl-7, 10-(di-3 ",5 "-dinitrobenzoyl)- 10-deacetyl baccatin III (the compound of formula (VII)) 7,10-(di-3',5'-dinitrobenzoyl)-10-deacetylbaccatin III and 610 mg of 4-(dimethylamino)pyridine were dissolved in 1.8 L of ethyl acetate, stirred at 25 °C , 52 g of dicyclohexylcarbodiimide was added thereto at 25 ^°C , stirred for 2 h, and the resulting mixture was filtered to obtain a filtrate and a dicyclohexylurea cake. After washing the cake with 200 ml of ethyl acetate, the filtrate and the ethyl acetate wash solution were combined, the combined organic layer was successively washed with 300 ml of 1 N HCl and 300 ml of saturated sodium bicarbonate, dried over anhydrous magnesium sulfate. The mixture was filtered and the filtrate was distilled under a reduced pressure. The residue was treated with 800 ml of acetonitrile, the resulting mixture was stirred for 1 h, and 800 ml of water was added dropwise thereto, stirred for 2 h, and filtered to obtain a solid. The solid thus obtained was added to 800 ml of acetonitrile, followed by stirring the mixture for 1 h, adding dropwise 800 ml of water thereto, and stirring the mixture for 2 h. The resulting mixture was filtered to obtain 134 g of the title compound as a solid (yield: 100%). m.p.: 202 °C ; [α]_D ²³ = 16. U (c = 1, CHCl₃); IR (KBr, cm⁴) 3560, 3446, 3102, 2977, 2939, 2897, 1740, 1718, 1628, 1548, 1547, 1344, 1268, 1162, 1069, 978, 919, 729, 718. 1H NMR (300 MHz, CDCl₃): δ 9.27 (m, IH), 9.20 (m, IH), 9.04 (m, 2H),

8.76 (m, 2H), 8.11 (d, J = 7.5 Hz, 2H), 8.02 (m, 2H), 7.62 (m, 2H), 7.53 - 7.43 (m, 13H), 6.30 (s, IH), 5.95 (t, J = 8.3 Hz, IH), 5.68 - 5.58 (m, 3H), 4.93 (d, J - 8.0 Hz), 4.68 (d, J = 4.3 Hz), 4.32 (d, J = 8.6 Hz, IH), 4.14 (d, J = 8.6 Hz, IH), 3.79 (d, J = 7.1 Hz, IH), 2.83 - 2.79 (m, IH), 2.20 - 1.98 (m, 6H), 1.90 (s, 3H), 1.56 (s, 3H), 1.25 (s, 3H), 1.19 (s, 3H), 0.86 (s, 12H).

Step 4: Preparation of 13-[(2'R,3'S)-3'-t-butoxycarbonylamino-3'-phenyl -2'-hydroxypropionyl]-7,10-(di-3",5"-dinitrobenzoyl)-10-deacetylbaccatin III (the compound of formula (VIII)) 134 g of the compound obtained in Step 3 was mixed with 670 ml of chloroform and 130 ml of methanol, 19.2 g of p-toluenesulfonic acid monohydrate was added dropwise to the mixture, which was stirred at room temperature for 3 h. The resulting organic layer was washed with 1.4 L of water containing 13 g of sodium bicarbonate, dried over anhydrous magnesium sulfate, and filtered. The filtrate was distilled under a reduced pressure to obtain a solid, the solid was dissolved in 1.2 L of diethyl ether, and 2.4 L of hexane was added dropwise thereto. After stirring at room temperature for 3 h, the solid formed therein was separated, dissolved in 330 ml of acetonitrile, 770 ml of water was added dropwise thereto, and stirred at room temperature for 3 h to induce precipitation. The solid formed was isolated by filtration to obtain 109 g of the title compound as a solid (yield: 91%). m.p.: 173 °C ; [α]_D ²³ = 8.9_O (c = 1, CHCl₃); IR (KBr, cm⁴) 3543, 3432, 3101, 2978, 2900, 1736, 1628, 1548, 1494, 1455, 1368, 1345, 1269, 1163, 1095, 1070, 978, 920, 730, 718.

¹H NMR (CDCl₃, 300 MHz): δ 9.27 (m, IH), 9.21(m, IH), 9.03 (m, 2H), 8.87 (m, 2H), 8.15 (d, J = 7.5 Hz, 2H), 7.65 (m, IH), 7.54 (m, 2H), 7.40 - 7.43 (m, 5H), 6.63(s, IH), 6.27 (m, IH), 5.88 (m, IH), 5.80 (d, J = 6.9 Hz, IH), 5.38 (d, J = 9.4 Hz, IH), 5.28 (m ,1H), 5.03 (d, J = 8.1 Hz, IH), 4.67 (d, J = 3.1 Hz, IH), 4.41 (d, J = 8.6 Hz, IH), 4.26 (d, J = 8.6 Hz, IH), 4.07 (d, J = 6.7 Hz, IH), 3.34 (d, J = 5.3 Hz, IH), 2.87 (m, IH), 2.46 (s, 3H), 2.42 (m, 2H), 2.01 - 2.05 (m, 3H), 2.01 (s, 3H), 1.87 (s, IH), 1.59 (s, 3H), 1.39 (s, 3H), 1.36 (s, 9H), 1.32 (s, 3H).

Step 5: Preparation of docetaxel (the compound of formula (H))

60 g of the compound obtained in Step 4 was mixed with 300 ml of methanol and 60 ml of morpholine, and the mixture was stirred at room temperature for 3 h. 500 ml of ethyl acetate was added dropwise thereto, followed by adding dropwise 700 ml of 1 N HCl thereto at O⁰C. The organic layer was separated, dried over anhydrous magnesium sulfate, filtered, and the filtrate was distilled under a reduced pressure. The residue was subjected to silica column chromatography to obtain 35 g of the title compound as a white solid (yield: 87%, HPLC purity: 99.0%).

Example 1

10 g of docetaxel (HPLC purity: 99.0%) obtained in Preparation Example was dissolved in 150 ml of dichloromethane and 15 ml of propylene glycol at room temperature, to which 200 ml of n-hexane was added dropwise, followed by stirring at room temperature for 12 h to induce crystal formation. The resulting mixture was filtered to obtain a solid. The solid was dried in an oven at 60 ^°C under a reduced pressure of 0.1 torr for 24 h to obtain 10.1 g of the title compound (yield: 92%). The inventive compound, docetaxel / mono propylene glycol clathrate, thus obtained was subjected to X-ray diffraction and NMR analysis, and the results are shown in FIGs. 2 and 3, respectively. HPLC purity: 99.7% 7-epimer content: 0.03% Docetaxel content: 91.2% m.p.: 208 - 214 ^°C Propylene glycol content: 8.4% Residual solvents: 20 ppm or less of dichloromethane and 5 ppm or less of n-hexane

Example 2

The procedure of Example 1 was repeated except for using ethyl acetate instead of dichloromethane as an organic solvent to obtain 9.8 g of the title compound (yield: 90%), which exhibited X-ray diffraction scan and NMR spectrum similar to those of the compound obtained in Example 1.

HPLC purity: 99.8%

7-epimer content: 0.04%

Docetaxel content: 91.0% m.ρ.: 210 - 215 ^°C

Propylene glycol content: 8.7%

Residual solvents: 113 ppm or less of ethyl acetate and 5 ppm or less of n-hexane

Stability Test

Stability tests were performed for the docetaxel / mono propylene glycol clathrate obtained in Example 1 and docetaxel trihydrate obtained by the conventional method described in U.S. Patent No. 6,022,985 as a comparative compound, as follows.

The compound of Example 1 and the comparative compound were each kept at 60 ± 2 ^°C and 75 ± 5% humidity (a stress condition) for 8 weeks. The chemical purity of the test compound at week 0, 1, 2, 4 and 8 was analyzed using liquid chromatography, and the results are listed in Table 1.

Table 1

As shown in Table 1, the inventive compound, docetaxel / mono propylene glycol clathrate, obtained in Example 1 exhibited an improved stability in maintaining its purity over the comparative compound, docetaxel trihydrate. This suggests that the inventive compound is a much more stable than docetaxel trihydrate.

Further, docetaxel / mono propylene glycol clathrate obtained in Example 1 was kept under a relative humidity of 25% or 50% at an external temperature of 40 °C (stress condition) for 1 week, followed by analyzing its purity and using HPLC, and it was found that the content and purity of docetaxel / mono propylene glycol clathrate had undergone no change.

Furthermore, the docetaxel / mono propylene glycol clathrate obtained in Example 1 was kept under a relative humidity of 90% at an external temperature of 30 °C for 72 h, followed by examining whether the crystal form had undergone any change by moisture absorption or the removal of propylene glycol by using X-ray diffraction and NMR analyses, and it was found that the crystal form remained unchanged. Thus, it can be seen that the inventive docetaxel / mono propylene glycol clathrate is non-hygroscopic and highly stable.

While the invention has been described with respect to the specific embodiments, it should be recognized that various modifications and changes may be made by those skilled in the art to the invention which also fall within the scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. The docetaxel / mono propylene glycol clathrate of formula (I):

2. The clathrate of claim 1, which contains docetaxel in an amount of 90 to 92.5% by weight and propylene glycol in an amount of 7.6 to 9.6% by weight, based on the total weight of the clathrate.

3. The clathrate of claim 1 , which has a 7-epimer content of 0.1 % or less.

4. A method for preparing the docetaxel / mono propylene glycol clathrate of formula (I), comprising the steps of dissolving docetaxel of formula (II) and propylene glycol in an organic solvent; adding to the resulting solution an anti-solvent to induce recrystallization; and harvesting the solid formed therein:

wherein, Ph is phenyl, Ac is acetyl, Bz is benzoyl, and Boc is ^-butoxycarbonyl.

5. The method of claim 4, wherein the harvesting step is conducted by filtering the recrystallized mixture to obtain a solid and drying the solid at a temperature of 20 to 80 °C under a reduced pressure of 0.1 to 10 torrs.

6. The method of claim 4, wherein the organic solvent is dichloromethane and ethyl acetate.

7. The method of claim 4, wherein the organic solvent is employed in an amount of 5 to 30 ml based on 1 g of docetaxel.

8. The method of claim 4, wherein propylene glycol is employed in an amount of 1 to 50 equivalents based on docetaxel.

9. The method of claim 4, wherein the anti-solvent is hexane.

10. The method of claim 4, wherein the anti-solvent is employed in an amount of 1 to 5 ml based on 1 ml of the organic solvent.