CA2211808C - Method for preparing 4,10-diacetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1,7.beta.-dihydroxy-9-oxo-tax-11-en-13.alpha.-yl (2r,3s)-3-benzoylamino-2-hydroxy-3-phenylpropionate trihydrate - Google Patents

Abstract

A method for preparing 4,10-diacetoxy-2 alpha -benzoyloxy-5 beta ,20-epoxy-1,7 beta -dihydroxy-9-oxo-tax-11-en-yl-13 alpha (2R,3S)-3-benzoylamino-2-hydroxy-3-phenylpropionate trihydrate by crystallisation from a water/alcohol solution.

Description

PROCESS FOR THE PREPARATION OF TRIHYDRATE
(2R 3S) -3-BENZOYLAMINO-2-HYDROXY-3-PHENYLPROPIONATE 410-Diacetoxy-2a-benzoyloxy-5 (3.2p-EPOXY-1.7 (3 - dihydroxy-9-oxo-TAX-11-EN-13a-YLE

The present invention relates to a process for preparing the trihydrate of (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate of 4,10-diacetoxy-2-en benzoyl-oxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl.

(2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate of 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3? -dihydroxy-9-oxo-tax-11-en-13a-yl (or paclitaxel) has anti-cancer and anti-leukemic properties remarkable.

(2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate of 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl can be either isolated from yew bark or prepared from the baccatin III or 10-desacetylbaccatin III according to the methods which are described more particularly in the European patent applications EP 0 336 840 or EP 0 400 971 or in the PCT International Application WO 94/07878.

It has been found that (2R, 3S) -3-benzoylamino-2-hydroxy-3 trihydrate 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy) phenylpropionate oxo-tax-11-en-13a-yl has a stability very much higher than that of anhydrous product.

According to the invention, (2R, 3S) -3-benzoylamino-2-hydroxy-3 trihydrate 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy) phenylpropionate oxo-tax-11-en-13a-yl can be obtained after crystallization of (2R, 3S) -3-4,10-Diacetoxy-2a-benzoyloxy benzoylamino-2-hydroxy-3-phenylpropionate (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl in a mixture of water and a aliphatic alcohol containing 1 to 3 carbon atoms, followed by drying of the product obtained under reduced pressure and then maintained in a humidity on greater than 20% at a temperature in the region of 25 C.

cr1 .., a e- ~ .- r ..-..... - --- ----- ----- - - -_ _. _. v ... w, ~ n. . ~ .. ~., ..,. , .., .._

2 For the implementation of the method according to the invention, it can be particularly advantageous - to put in solution or in suspension the (2R, 3S) -3-benzoylamino-2-hydroxy-3-4,10-diacetoxy-2a-benzoylo.ay-5 (i, 20-epoxy-1,7 (3-dihydroxy) phenylpropionate oxo-tax-11-en-13a-yl in an aliphatic alcohol containing 1 to 3 carbon atoms carbon, - treat the solution or suspension with water containing possibly a base mineral such as sodium hydrogencarbonate, - to separate the cristau_x obtained, then - to dry them under reduced pressure, then - to maintain them possibly in an atmosphere whose relative humidity is higher at 20% at a temperature of 25 C.
Generally, (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl is dissolved in an excess of the aliphatic alcohol, preferably methanol.
Of preferably, the amount of alcohol is between 6 and 12 parts by weight compared 4,10-Diacetoxy-2α (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl used.
Generally, water is added in such a way that the weight ratio water / alcohol is between 3/1 and 1/3. The added water can hold up to 10% (w / v) of a mineral base such as sodium hydrogencarbonate so that the pH of reaction mixture is greater than or equal to 7, preferably between 7 and 8, before the separation of the crystals.
(2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate trihydrate 4,10-Diacetoxy-2a-benzoyl., 5-ry-3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-ene) 13a-yl which crystallizes is separated, preferably by filtration or centrifugation, then dried. The drying is carried out under reduced pressure, between 1 and 7 kPa, at a temperature close to 40 C and the product obtained is possibly stabilized with a water content of 6% in an atmosphere whose relative humidity It is 9% by 20% and has a temperature of 0 ° to 60 ° C.
préférenae wisin of 25 C.
For the implementation of the method, it may be advantageous to carry out the crystallization in the presence of ascorbic acid which is added during the dissolution or

3 suspending (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate of

4,10-Diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl in alcohol. It is possible to use up to 1% by weight of acid ascorbic.que.
It should be noted that (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenyl-4,10-Diacetoxy-2a-benzoyloxy-5p, 20-epoxy-1,7R-dihydroxy-9-oxo propionate tax-11-en-13a-yl is obtained in the form of an ester resulting from esterification of Baccatin III whose hydroxy function in -13 is protected by a derivative of the R-phenylisoserine protected after removal of the protective groups, and the crystallization is carried out directly in situ on this ester.

(2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate trihydrate 4,10-Diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-ene) 13a-yl has been studied by thermogravimetric and differential calorimetric analyzes and by diffraction by X-rays.
In particular, the thermonimetric analysis shows a loss of mass between 25 and 140 C close to 6%, which corresponds to three molecules water for a molecule of (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate 4,10-Diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl.
For the implementation of the product according to the invention, when using semi-synthetic paclitaxel obtained according to the methods which are described by example in the European patents EP 0 336 840 or EP 0 400 971 or in the -demand PCT International Patent No. WO 94/07878 which intermediately lead to paclitaxel whose the hydroxy functions are protected, it is possible to operate directly on the solution or suspension of (2R, 3S) -3-benzoylamino-2-hydroxy-3 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1,7 (3-dihydroxy) phenylpropionate oxo-tax-11-en-13a-yl obtained after removal of the protective groups of the hydroxy functions of the taxane cycle and the side chain. For example, in operating under the conditions of PCT international application WO 94/07878, we obtain Intermediately (4S, 5R) -3-benzoyl-2- (4-methoxy-phenyl) -4-phenyl-1,3-4,10-Diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1) oxazolidine-5-carboxylate hydroxy 3a 7 (3-triethylsilyloxy-9-oxo-tax-11-en-13a-yl whose protective groups can be eliminated using trifluoroacetic acid in methanol.
The following examples illustrate the present invention.

In a reactor protected from light, 5.014 g of (4S, 5R) -3-benzoyl-2- (4-methoxyphenyl) -4-phenyl-1,3-oxazolidine-5-carboxylate of 4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy-1-hydroxy-7 (3-triethylsilyloxy-9-oxo-Tax-èn-13a-yl whose title is 98% (4.52 mmol) and 50 cm3 of methanol. To the stirred white suspension, 7 cm3 of acid are added rapidly trifluoroacetic. The temperature rises to around 35 C. After cooling to a temperature close to 5 C, we add 110 cm3 of an aqueous solution of hydrogen carbonate of sodium at 6% (w / v). The pH is 7. The crystals are separated by filtration on glass sintered and washed with 4 times 15 cm3 of a mixture methanol-water (30-70 in volumes).
After drying under reduced pressure at 35 ° C., 3.676 g of (2R, 3S) -3-4,10-Diacetoxy-2a-benzoyloxy benzoylamino-2-hydroxy-3-phenylpropionate

(3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl grading 93.1% and containing about 4.8% water.

The product obtained is characterized by the X-ray powder diagram represented by FIG.

The yield of pure product is 89.3% relative to the ester put in artwork.

Maintained in conditions of relative humidity greater than 20%, the product stabilizes with a water content close to 6%. The DPRX diagram (X-ray powder diagram), shown in Figure 2, shows that the product obtained is in the form of a trihydrate (theoretical value of content water of (2R, 3S) -3-benzoylamino-2-hydroxy-3-phenylpropionate trihydrate 4,10 diacetoxy-2a-benzoyl-oxy-5 (3,20-epoxy-1,7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl of 5.95%).

The X-ray powder diagram is made by means of a device Philips PW 1700 with cobalt anti-cathode Q tube, Kal = 1.7889 A), sweeping being performed at an initial scan angle of 5 2-0, final scan of 40 with a step of 0.02 0 2-0 at a rate of 1 second per step and using a pastille silicon.

tl In a reactor protected from light, 3.006 g of (4S, 5R) -3-benzoyl-2- (4-methoxyphenyl) -4-phenyl-1,3-oxazolidine-5-carboxylate of 4,10-acetoxy-2a-benzoyloxy-5 (3,20-epoxy-1-hydroxy-7,3-triethylsilyloxy-9-oxo) tax-11-5-en-13a-yl whose title is 98% (2.70 mmol) and 30 cm3 of methanol. AT
the stirred white suspension, 6.3 cm3 of 99% trifluoroacetic acid is added.
After cooling to a temperature of 5 C, 7.5 cm3 of water are added demineralized in 15 minutes. The crystals are separated by filtration on glass sintered and washed 3 times with 5 cm3 of a methanol-water mixture (80-20 by volume) at 5 ° C.
After drying under reduced pressure at 35 ° C., 1.989 g of (2R, 3S) -3-benzoylamino-4,10-diacetoxy-2a-benzoyloxy-5 (3,20-epoxy) -2-hydroxy-3-phenylpropionate 1.7 (3-dihydroxy-9-oxo-tax-11-en-13a-yl grading 97.8% and containing about 6.8%
of water.

The yield is 84.3% relative to the ester used.
, , - -

Claims

1- Process for the preparation of (2R,3S)-3-benzoylamino-trihydrate 4,10-diacetoxy-2.alpha.-benzoyloxy-5.beta.,20-2-hydroxy-3-phenylpropionate epoxy-1,7.beta.-dihydroxy-9-oxo-tax-11-en-13.alpha.-yl characterized in that one crystallize it 4,10-diacetoxy-2.alpha.-(2R,3S)-3-benzoylamino-2-hydroxy-3-phenylpropionate benzoyloxy-5.beta.,20-epoxy-1,7.beta.-dihydroxy-9-oxo-tax-11-en-13.alpha.-yl in a mixture of water and an aliphatic alcohol containing 1 to 3 carbon atoms, the water/alcohol weight ratio being between 3/1 to 1/3, then the product obtained under reduced pressure and maintained under conditions relative humidity greater than 20%.

2- Process according to claim 1, characterized in that the alcohol is methanol.

3- Process according to claim 1 or 2, characterized in that the drying is carried out at a temperature close to 40°C under pressure scaled down and that the product obtained stabilizes with a water content of 6% in a atmosphere in which the relative humidity is greater than 20%.

4- Process according to any one of claims 1 to 3, characterized in that the crystallization is carried out in the presence of up to 1%
by weight of ascorbic acid.

5- Process according to any one of claims 1 to 4, characterized in that (2R,3S)-3-benzoylamino-2-hydroxy-3-phenylpropionate 4,10-diacetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-1,7.beta.-dihydroxy-9-oxo-tax-11-en-13.alpha.-yl is obtained as an ester resulting from the esterification of baccatin III whose hydroxy function at -13 is protected by a derivative of .beta.-protected phenylisoserine after removal of the protective groups, and in that the crystallization is carried out directly in situ on this ester.

6- (2R,3S)-3-benzoylamino-2-hydroxy-3-trihydrate 4,10-diacetoxy-2.alpha.-benzoyloxy-5.beta.,20-epoxy-phenylpropionate 1.7.beta.-dihydroxy-9-oxo-tax-11-en-13.alpha.-yl.