WO1993002064A1

WO1993002064A1 - Novel 7-deacetoxy baccatine iv derivative, and preparation and use thereof

Info

Publication number: WO1993002064A1
Application number: PCT/FR1991/000585
Authority: WO
Inventors: Alain Ahond; Laurent Ettouati; Pierre Potier; Christiane Poupat
Original assignee: Centre National De La Recherche Scientifique (Cnrs)
Priority date: 1991-07-16
Filing date: 1991-07-16
Publication date: 1993-02-04

Abstract

A novel 7-deacetoxy baccatine IV derivative having formula (I), the preparation thereof from taxine B, and its use in preparing biologically active products, are described. In said formula (I), R is a hydrogen atom or acetyl radical and R1, R2, R3, and R4 are hydroxy-function protective groupings (preferably acetonides).

Description

NEW DERIVATIVE OF 7-DESACETOXY BACCATIN IV. PREPARATION AND USE

The present invention relates to a new derivative of 7-deacetoxy baccatin IV of general formula:

in which R represents a hydrogen atom or an acetyl radical and the symbols R 1, R 2, R 3 and R 4 represent groups protecting the hydroxy function, its preparation and its use for the preparation of therapeutically active taxane derivatives .

Taxane derivatives of general formula:

in which R5 represents a hydrogen atom or an acetyl radical and R represents a tbutoxy or phenyl radical have remarkable anti-tumor and anti-leukemic properties.

The product of general formula (II) in which R5 represents an acetyl radical and Rβ represents a phenyl radical is known under the name of taxol and the product of general formula (II) in which R5 represents a hydrogen atom and Rβ represents a tbutoxy radical are described in European patent EP 0253 738.

According to American patents US 4,924,011 and US 4,924,012, it is known to prepare the products of general formula (II) by esterification, by means of a suitably substituted β-phenylglycidic acid, under appropriate conditions, baccatin m or 10-deacetyl baccatin III of formula:

OCOC ₆ H ₅ in which R5 is defined as above

Baccatin m, and more particularly 10-deacetyl baccatin m, can be extracted from the leaves of the yew (Taxus baccata). The content of these products remains relatively low although very much higher than that of taxol; moreover, it is mainly found in the bark of the trunk.

It is also known that from the leaves of various varieties of yew can be extracted from many alkaloids, the main constituent of which is taxin B of formula:

Studies carried out on taxol and its derivatives have made it possible to show, in particular, that the presence of the oxetane ring in position 4,5 of the taxane skeleton is an essential element for the manifestation of a biological activity. As a result, the introduction of an oxetane ring on taxin B to replace the methylene group exo (4.20) and that of the ester function at 5 can lead to the formation of intermediates which are particularly advantageous for the preparation of taxol. or its derivatives or analogous compounds having biological activity.

The subject of the present invention is the product of general formula (I) and its preparation from taxin B.

More particularly, the present invention relates to the product of general formula (I) in which the alcohol functions in 1,2, on the one hand, and in 9,10, on the other hand, are protected in the form of acetonides ; in this general formula product:

R represents a hydrogen atom or the acetyl radical.

According to the invention, the product of general formula (I), and more particularly the product of general formula (V) can be obtained from taxin B by carrying out, after transformation according to known methods, taxin B into triacetylcinnamoyl taxicin I of formula:

OCOCHg the succession of the following stages:

i) (XIV) (V)

According to the present invention, the triacetylcinnamoyltaxicin I of general formula (VI) is obtained from the crude extract of yew leaves essentially containing taxin B, after quatemization using for example iodide of methyl and deamination in basic medium, by acetylation followed by chromatographic separation.

The triacetylcinnamoyltaxicin I of formula (VI) is transformed into 5α-cinnoyoylaxicin I of formula (VII) by solvolysis in basic medium. Generally, an alkaline alcoholate such as sodium methylate is used in the corresponding alcohol such as methanol, optionally in the presence of a second anhydrous organic solvent such as methylene chloride. It is particularly advantageous to use a 0.1N solution of sodium methylate in methanol.

Deacetylation can also be carried out using an alkaline cyanide such as potassium cyanide.

The protection of the hydroxy functions of the product of formula (Vu) in the form of acetonides in order to obtain the product of formula (VIII) is preferably carried out using acetone in the presence of an acid catalyst such as sulfuric acid. concentrated. Good results are also obtained using 2,2-dimethoxypropane in the presence of p.toluenesulfonic acid.

The product of formula (IX) is obtained by eliminating the cinnable group from the product of formula (VIII) by means of a base. It is particularly advantageous to use a concentrated solution of an alkali hydroxide, such as 20N sodium hydroxide, in an organic solvent such as tetrahydrof uranium. The product of formula (X) can be obtained by dihydroxylation of the product of formula (IX) under the conditions described by V. Van Rheenen et al., Tetrahedron Letters, 1973-1976 (1976) using tetrahydrofuran instead of l acetone as a co-solvent and using a higher amount of osmium tetroxide and N-methylmorpholine N-oxide as a secondary oxidant. The protection of the primary alcohol function of the product of formula (X) to obtain the product of general formula (XI), in which the symbols R7, identical or different, each represent an alkyl radical containing 1 to 4 carbon atoms, is generally carried out by the action of a halotrialkylsilane on the product of formula (X) by operating in an organic solvent such as dimethylformamide in the presence of an acid acceptor such as rimidazole. It is particularly advantageous to use dimethylterbutylsilyl chloride which allows selective protection. Furthermore, the dimethylterbutylsilyl protective group is more easily eliminated by fluoride ions in the presence of acetonides. The product of general formula (XI), in which R7 is defined as above, is transformed into a mesylated product of general formula (XII) by means, for example, of an excess of mesyl chloride in the pyridine:

The product of formula (XIII) is generally obtained by the action of a fluoride, such as tetrabutylammonium fluoride on the product of general formula (XII). It is particularly advantageous to operate in an inert organic solvent such as tetrahydrofuran at a temperature in the region of 20 ° C.

The product of formula (XTV) can be obtained either from the product of formula (XIII) or directly from the product of general formula (XII). Generally, the transformation of the product of formula (XIII) into the product of formula (XIV) is carried out by means of tetrabutylammonium acetate in butane at the reflux temperature of the reaction mixture.

The transformation of the product of formula (XII) into the product of formula (XTV) can be carried out by means of tetrabutylammonium fluoride in an organic solvent such as tetrahydrofuran at the reflux temperature of the reaction mixture.

The product of formula (XTV), the tertiary alcohol function of which is optionally acetylated, can be reduced stereoselectively to the product of general formula (V). Generally the reduction is carried out by means of diisobutylaluminium hydride by operating in an anhydrous organic solvent such as toluene at a temperature close to 0 ° C.

The product of general formula (I), and more particularly the product of general formula (V) can be transformed into precursors, for example of the product of general formula (II) after having carried out a set of reactions the result of which will have the effect of 'to have :

- esterified the 13α-hydroxy function,

- eliminated the protective groups of the hydroxy functions in 1, 2, 9 and 10

- oxidized the 9α-hydroxy function

- introduces a 7α-hydroxy function - benzoylated the 2α-hydroxy function.

The following examples show how the invention can be put into practice.

EXAMPLE 1 Preparation of 2α, 9α, 10β-triacetyl-5α-c_nnamoyltaxic_ne I

1) 28 kg of yew leafy stalk powder are treated with 13.5 liters of ammonia and then placed in 2 macerators. Then methylene chloride is added. Each day, for 10 days, the macerators are emptied and methylene chloride is added.

The methylene chloride is concentrated to a final volume of 80 liters. The alkaloids are selectively extracted with 175 liters of 2% hydrochloric acid (w / v). The acidic aqueous phase is washed with 75 liters of hexane, basified with 3.6 liters of concentrated ammonia and then extracted with 80 liters of methylene chloride. After drying the chloromethylenic solution over 200 g of sodium sulphate, filtration and concentration to dryness, 192 g of a yellowish amorphous powder consisting of total alkaloids are obtained. The yield is 6.86 g of total alkaloids per kilogram of dry plant.

2) A solution of 26 g of total alkaloids in 80 cm3 of tetrahydrofuran is introduced into a 250 cm3 flask fitted with a stirrer, and then 15 cm3 of methyl iodide are added dropwise. After 5 hours of stirring at a temperature in the region of 20 ° C, the solvent is removed under reduced pressure. 32.5 g of a yellowish powder are thus obtained.

3) The powder obtained above is dissolved in 250 cm3 of absolute ethanol and then the solution is added, over 1 hour, drop by drop, at 20 ° C., to 350 cm3 of an aqueous potassium carbonate solution at 2 % (w / v). A yellow precipitate is formed which dissolves. After 3 hours of stirring, the ethanol is removed by concentration and then extracted with 6 times 100 cm3 of methylene chloride. After drying the organic extracts over magnesium sulfate, filtration and dry concentration, 23 g of a yellow powder are obtained.

4) The powder thus obtained is dissolved in 50 cm3 of anhydrous pyridine and 30 cm3 of acetic anhydride at 20 ° C. After 3 days of reaction, 40 cm 3 of absolute ethanol are added at 0 ° C. and then concentrated to dryness.

The residue is taken up in 150 cm3 of ethyl acetate. The solution is washed with 3 times 100 cm3 of 0.25N hydrochloric acid and then with 100 cm3 of distilled water. After drying over magnesium sulfate, filtration and concentration to dryness, 24 g of powder are obtained. 22 g of the powder thus obtained adsorbed on 100 g of silica (60-200 μm) are chromatographed on a silica column (40-60 μ; diameter 10 cm; height 17 cm), eluting with a heptane-acetate mixture. ethyl (6-4 by volume). After separation of 2 g of taxinine, 11.5 g of 2,9α, 10β-triacetyl-5α-cinnamoyltaxicin I are obtained, with a yield of 52%, the characteristics of which are identical to those described by JN Baxter et al., J. Chem. Soc., 2964-2971 (1962). EXAMPLE 2 Preparation of 5α-cinnamoyltaxicin I

5α-cinnamoyltaxicin I can be prepared according to one of the following methods:

1) At 57 mg (0.09 mole) of 2, 9α, 10β-triacetyl-5 -c_nnamoylt__xicine I dissolved in 5 cm3 of methanol and 1 cm3 of methylene chloride, 26 mg of sodium methylate in methanol (0.05N). After 6 hours 30 minutes of reaction, neutralization is carried out by adding 0.1N hydrochloric acid. After concentration, extraction with ethyl acetate and washing with distilled water, the organic phase is dried over magnesium sulfate. After concentration, the product obtained is chromatographed on a silica gel plate in a methylene chloride-methanol mixture (95-5 by volume). 18.2 mg of 5α-cinnamoyltaxicin I are thus obtained, the characteristics of which are identical to those described by J.N. Baxter et al., J. Chem. Soc., 2964-2971 (1962). The yield is 41%.

2) To 8 g of 2α, 9α, 10β-triacetyl-5α-cinnamoyltaxicin I in 17.5 cm3 of methylene chloride and 25 cm3 of methanol, 229 mg of sodium methylate is added at 0 ° C. After 50 hours of reaction, neutralization is carried out with 0.1N hydrochloric acid. After concentration under reduced pressure, extraction with ethyl acetate, washing with distilled water, drying over magnesium sulfate and filtration, the organic phase is concentrated to dryness. After chromatography on silica, eluting with a heptane-ethyl acetate mixture (6-4 by volume), 4 g of 5α-cinnamoyl-taxicin I are obtained. The yield is 62%.

3) To 2.5 g of 2α, 9α, 10β-triacetyl-5α-cinnamoyltaxitine I dissolved in 5 cm3 of methanol and 2 cm3 of methylene chloride, 165 mg of potassium cyanide are added. After 4 days of stirring at 20 ^β C, 170 mg of potassium cyanide are added.

After 6 days of stirring, the reaction mixture is concentrated and then extracted with an ethyl acetate-water mixture. After decantation, the organic phase is washed with distilled water and then dried over magnesium sulfate. After filtration and concentration, the residue is chromatographed on silica, eluting with a heptane-ethyl acetate mixture (6-4 by volume). 934 mg of 5α-cinnamoyl-taxicin I are thus obtained. The yield is 47.

EXAMPLE 3 Selective protection of the hydroxy functions One operates according to one of the following methods:

1) To 4 g of 5α-cinnamoyltaxicin I in 12 cm2 of distilled acetone, 12 drops of concentrated sulfuric acid are added at 0 ° C. After 48 hours of reaction to 0 ° C, 25 cm3 of a saturated aqueous sodium bicarbonate solution are added. After extraction with methylene chloride, the organic phases are washed with water and then dried over magnesium sulfate. After filtration and dry drying, the residue is chromatographed on silica eluting with a heptane-ethyl acetate mixture (9-1 by volume). 3.2 g of the product of formula (V_H) are thus obtained, the characteristics of which are the following:

- melting point: 148-150 ° C (ethanol)

- rotary power: [] j) = + 204 ° (c = 0.84; ethanol)

The structure of the product obtained is confirmed by the mass spectrum (chemical ionization), the infrared spectrum and the nuclear magnetic resonance spectrum of the proton.

2) A 42 mg of 5α-c_nnamoyltaxicin I in 1 cm3 of 2,2-dimethoxypropane is added a catalytic amount of p.toluenesulfonic acid. After 8 days of reaction, the reaction mixture is diluted with a 5% aqueous sodium bicarbonate solution. After extraction with ethyl acetate, the organic phase is washed with distilled water and then dried over magnesium sulfate. After filtration and concentration, the residue is treated on a silica gel plate in methylene chloride. 29 mg of the product of formula (Vm) are thus obtained.

EXAMPLE 4 Basic hydrolysis of the product of formula (VDI) 751 mg of the product of formula (VI) is dissolved in 12 cm3 of tetrahydro¬ furan and 4 cm3 of 20N sodium hydroxide. The mixture is heated at reflux for 4 days. After cooling, the reaction mixture is diluted with distilled water and then extracted with methylene chloride. The organic phase is washed several times with an aqueous solution of sodium chloride and then dried over sodium sulfate. After filtration and concentration to dryness, 568 mg of the product of formula (IX) are obtained, the characteristics of which are as follows:

- melting point: 254-256 ° C (ethanol)

- rotary power: [a]) = + 241 ° (c = 1.42; chloroform)

- ultraviolet spectrum: λ max = 272 nm ε = 3300 (ethanol) The structure of the product obtained is confirmed by the infrared spectrum, the mass spectrum (chemical ionization) and the nuclear magnetic resonance spectra of the proton and ^ C. EXAMPLE 5 Dihydroxylation of the product of formula (IX)

608 mg of the product of formula (IX) are dissolved in 8 cm3 of tetrahydrofuran and 4 cm3 of water. 2.39 g of N-methylmorpholine N-oxide and 1.15 cm 3 of a 2% (w / v) solution of osmium tetroxide in tbutanol are then added. The solution becomes reddish. After 19 hours of reaction, 400 mg of Florisil, 5 cm 3 of water and 50 mg of sodium hydrosulfite are added. After 10 minutes of stirring, filter on sintered glass and then neutralize the filtrate by adding 0.1N hydrochloric acid. After concentration under reduced pressure, the mixture is acidified to pH = 4, saturated with sodium chloride and then extracted with ethyl acetate. After drying the organic phase and concentrating to dryness, the residue is chromatographed on silica eluting with a heptane-ethyl acetate mixture (6-4 by volume). 530 mg of product of formula (X) is obtained, with a yield of 81%, the characteristics of which are as follows:

- melting point: 102-104 ° C (ether-heptane) - rotary power: [a] τ) = + 8.5 ° (c = 1.62; chloroform)

The structure of the product obtained is confirmed by the infrared spectrum, the mass spectrum (chemical ionization) and the proton nuclear magnetic resonance spectrum.

EXAMPLE 6 Protection of the primary alcohol function of the product of formula (X) 644 mg of imidazole and 586 mg of dimethylterbutylsyl chloride are dissolved in 5 cm3 of dimethylformamide. After 15 minutes, 336 mg of the product of formula (X) is added. After 16 hours of reaction, the reaction mixture is poured onto crushed ice. The precipitate formed is separated, washed with distilled water and then taken up in ethyl acetate. The organic phase is dried over magnesium sulfate. After filtration and concentration to dryness, 422 mg of product of formula (XI) are obtained in which two of the symbols R7 represent a methyl radical and the third a terbutyl radical, the characteristics of which are as follows:

- melting point: 178-180 ° C (ethanol)

- rotary power: [] j) = + 188 ° (c = 0.47; chloroform) The structure of the product obtained is confirmed by the infrared spectrum, the mass spectrum (electronic impact) and the nuclear magnetic resonance spectrum of the proton.

The yield is close to 100%. EXAMPLE 7 - Mesylation of the product of formula (XI)

To a solution of 422 mg of the product of formula (XI) obtained in Example 6 in 10 cm3 of pyridine, 0.25 cm3 of methanesulfonyl chloride is added dropwise at 0 ° C, then the temperature is allowed to return to around 20 ° C. After 17 hours of reaction, 70 cm 3 of methylene chloride are added. The organic phase, separated by decantation, is washed with a 0.01N hydrochloric acid solution and then with a saturated solution of sodium bicarbonate and finally dried over magnesium sulfate. After filtration and evaporation of the solvent, 421 mg of the product of formula (XII) is obtained with a yield of 88%, in which R7 is defined as in Example 6, the characteristics of which are as follows:

- amorphous powder

- rotary power: [α] rj = + 186 ° (c = 1.48; chloroform)

The structure of the product obtained is confirmed by the infrared spectrum, the mass spectrum (electronic impact) and the proton nuclear magnetic resonance spectrum.

EXAMPLE 8 Deprotection of the Product of Formula (XII)

To a solution of 421 mg of the product of formula (XII) in 5 cm3 of tetra¬ hydrofuran, 237 mg of tetrabutylammonium fluoride trihydrate is added at a temperature of 20 ° C. After 1 hour of reaction, diluted with ethyl acetate, then washed with a saturated solution of sodium bicarbonate. The organic phase is dried over magnesium sulfate. After filtration and evaporation of the solvent, the residue is chromatographed on silica, eluting with a heptane-ethyl acetate mixture (5 to 5 by volume). There is thus obtained, with a yield of 88%, 308 mg of product of formula (XH3) the characteristics of which are as follows: - amorphous powder

- rotary power: [α] j) = + 243 ° (c = 1.08; chloroform)

EXAMPLE 9 Preparation of the product of formula (XTV) from the product of formula (xm)

To a solution of 29 mg of the product of formula (XIII) in 1 cm 3 of butane, 158 mg of tetrabutylammonium acetate is added. After 19 hours of reaction, ethyl acetate is added. The organic solution is washed with a solution 0.1N hydrochloric acid then with saturated sodium chloride solution and finally dried over magnesium sulfate. After filtration and concentration to dryness, 19.3 mg of product of formula (XTV) is obtained with an 80% yield, the characteristics of which are as follows: - amorphous powder

- rotary power: [a] τ) = + 213 ° (c = 0.76; chloroform)

The structure of the product obtained is confirmed by the infrared spectrum, the mass spectrum (chemical ionization, electronic impact) and the nuclear magnetic resonance spectra of the proton and l ^ C.

EXAMPLE 10 Preparation of the product of formula (XTV) from the product of formula (XII)

10.6 mg of the product of formula (XII) are dissolved in 1 cm 3 of tetrahydrofuran then is added, at reflux, 20 mg of tetrabutylammonium fluoride. After 15 hours of reaction, ethyl acetate is added. The organic phase is washed with distilled water and then dried over magnesium sulfate. After filtration and evaporation of the solvent, the residue is treated on a preparative plate of silica gel in a hexane-ethyl acetate mixture (6-4 by volume). 1.6 mg of product of formula (XTV), the characteristics of which are identical to those of the product obtained in Example 9, are thus obtained with a yield of 22%.

EXAMPLE H - Selective reduction of the product of formula (XIV)

To 36.5 mg of product of formula (XTV) dissolved in 1 cm3 of toluene, 0.4 cm3 of a 1M solution of diisobutylaluminum hydride in toluene at 0 is added under an argon atmosphere ° C. After 1 hour, methanol is added dropwise and the mixture is then stirred for 15 minutes. After filtration and evaporation of the solvent, the residue is treated by chromatography on a preparative plate of silica gel in the heptane-ethyl acetate mixture (6-4 by volume). 14.3 mg of product of formula (V) are thus obtained, with a yield of 39%, the characteristics of which are the following:

- amorphous powder - rotary power: [a] γ) ≈ + 88 ° (c = 0.1; chloroform)

- infrared spectrum: characteristic bands at 3444, 1381, 1375, 1237 and 1050 cm ^~ l

- mass spectrum (chemical ionization) (T = 190 ° C, m / z): 447 (MH + -H2O), 407

(MH ⁺ -acetone), 389 (447-acetone), 371 (389-H ₂ O), 331 (389-acetone), 313 (331- H ₂ O) - proton nuclear magnetic resonance spectrum (400 MHz; deuterated chloroform):

SS ssms

EXAMPLE 12 Acetylation of the product of formula (XIV)

Under the standard acetylation conditions (acetic anhydride-pyridine; 4-dimethylaminopyridine), the product of formula (XTV) is acetyl in position 4 with a yield of 58%. The product obtained has the following characteristics:

- amorphous powder

- rotary power: [a]) = + 229 ° (c = 0.38; chloroform)

EXAMPLE 13 Esterification of the product of formula (V)

To a solution of 7.1 mg of product of formula (V) in 0.5 cm3 of methylene chloride, 9 mg of cinnamic acid, 12.6 mg of dicyclohexylcar- are added. bodiimide and 2 mg of 4-dimethylaminopyridine. After 2 hours of reaction, the reaction mixture is filtered. The filtrate is washed with a 0.01N hydrochloric acid solution and then with 0.5N sodium hydroxide. The organic phase is dried over magnesium sulfate. After filtration and evaporation of the solvent, the residue is treated on a preparative silica gel plate in the heptane-ethyl acetate mixture (7-3 by volume). 5.2 mg of the 13α-cinnamoylated derivative of the product of formula (V) are thus obtained with a yield of 57%. The product obtained has the following characteristics:

- amorphous powder

- rotary power: [CC] D = + 342 ° (c = 0.45; chloroform) The structure of the product obtained is confirmed by the infrared spectrum, the mass spectrum (chemical ionization) and the nuclear magnetic resonance spectrum of the proton.

Claims

REVENPICAπONS 1 - A new derivative of the general formula 7-deacetoxy baccatin IV

in which R represents a hydrogen atom or the acetyl radical and Rj, R2, R3 and R4 represent a group protecting the alcohol function.

2 - A new derivative of 7-deacetoxy baccatin IV of general formula:

in which R represents a hydrogen atom or an acetyl radical.

3 - A process for preparing a product according to claim 1 caracté¬ ized in that one selectively reduces a product of formula:

wherein R, R \, R, R3 and R4 are defined as in claim 1. 4 - A process for the preparation of a product according to claim 2 caracté¬ ized in that one selectively reduces a product of formula:

wherein R is defined as in claim 2.

5 - A process for preparing the product of general formula

OR ₄ in which R, Rj, R, R3 and R4 are defined as in claim 1 charac¬ terized in that:

- taxine B is transformed, according to known methods, into 5α-cinnamoyltaxicin I, - the functions, lβ-, 2a-, 9a- and lOβ-hydroxy of 5α-cinnamoyltaxicin 1 are protected,

- 4.20 dihydroxylation is carried out on the product thus obtained,

- the primary alcohol function is protected in the form of a silylated derivative,

the product obtained is treated with methanesulfonyl chloride to obtain the Sa¬ mesylate,

then an oxetane ring is formed on the product obtained by the action of tetrabutylammonium acetate or fluoride, and

- the product obtained is isolated.

6 - The product of general formula:

wherein R, Rj, R2, R3 and R4 are defined as in claim 1.

7 - A process for preparing the product of formula

in which R is defined as in claim 1 characterized in that:

taxine B is transformed, according to known methods, into 5α-cinnamoyltaxicin I,

the functions lβ-, 2a-, 9a- and lOβ-hydroxy of 5α-cinnamoyltaxicin I are protected in the form of acetonides;

- 4.20 dihydroxylation is carried out on the product obtained, - the primary alcohol function is protected in the form of a silylated derivative,

the product obtained is treated with methanesulfonyl chloride to obtain the 5amesylate,

- Then an oxetane ring is formed on the product obtained by the action of acetate or tetrabutylammonium fluoride, and - the product obtained is isolated. 8 - The product of formula:

in which R represents a hydrogen atom or the acetyl radical.

9 - A process for the preparation of therapeutically active taxane derivatives characterized in that a product according to one of claims 1 or 2 is used, and taxane derivatives thus obtained.