IE914072A1 - New pyridobenzindole derivatives, their preparation and¹compositions containing them - Google Patents

Abstract

Novel pyridobenzoindole derivatives having general formula (I), where R is H or C1-2 alkyl, alk is linear or branched C2-4 alkylene, R1 is a hydrogen atom or a C1-2 alkyl radical, and R2 is a hydroxy or methoxy radical, and acid addition salts thereof, are useful as antitumoral agents.

Description

The present invention relates to pyridobenzindole derivatives, their preparation and compositions containing them.

In European Patent Application 239,476, 5 y-carboline derivatives of formula: in which R3 and R5 can be, inter alia, hydrogen, R2 can represent hydrogen, hydroxyl or alkyloxy, R3 and R4 may be alkyl, and n is 2 to 4, have been described. These compounds are stated to possess antitumour activity.

Pyridoindole derivatives unsubstituted at the 4-position have been described in the literature [J. Med. Chem., 21, 398 (1988)] as inactive compounds.

The present invention provides, as new 15 compounds, the pyridobenzindole derivatives of formula and, where appropriate, their hydrates and their acid IE - 3 addition salts, in which R represents a hydrogen atom or an alkyl radical containing 1 or 2 carbon atoms, alk represents a linear or branched alkylene radical containing 2 to 4 carbon atoms, R^ represents a hydrogen atom or an alkyl radical containing 1 or 2 carbon atoms, and R2 represents a hydroxyl or methoxy radical. These compounds possess especially advantageous antitumour properties.

According to a feature of the invention, the products of formula (I) are obtained from the chlorinated derivatives of formula: in which R^ is as defined above, by reaction with an amine of formula: H2N - alk - N(R)2 (III) in which alk and R are as defined above, followed, where appropriate, by conversion of the methoxylated product thereby obtained, of formula - 4 H3CO (la) in which R, Rj and alk are as defined above, into a 9-hydroxypyrido[4,3-b]benz[e]indole.

The reaction of the amine of formula (III) with the chlorinated derivative of formula (II) is performed in the presence of an excess of the amine, preferably under nitrogen, optionally in an inert organic solvent, or without a solvent, at a temperature between the refluxing temperature of the reaction mixture and 250°C (in an 10 autoclave).

The demethylation can be performed by any known method which does not adversely effect the remainder of the molecule.

The chlorinated derivative of formula (II) in 15 which Rj is hydrogen may be prepared from the corresponding by the action of a chlorinating agent. - 5 The chlorination is generally accomplished by means of a chlorinating agent selected from phosphorus oxychloride and halogenated phosphorus derivatives, in the presence of a tertiary base (e.g. diethylaniline, or dimethylaniline), in an organic solvent such as a nitrile (e.g. acetonitrile), at a temperature of between 75 and 90°C (or the reflux temperature of the reaction mixture). Preferably, the reaction is performed under nitrogen.

The product of formula (II) in which R^ is an 10 alkyl radical may be obtained by alkylation of the product in which R^ is a hydrogen atom, e.g. by the action of the appropriate halogenated derivative in the presence of potassium carbonate.

The pyridone of formula (IV) may be prepared 15 from the hydrazone of formula: by a Fisher thermal reaction, by analogy with the method described by C.H. Nguyen and E. Bisagni, Tetrahedron, 42. (8), 2203 (1986).

The hydrazone of formula (V) is prepared by the condensation of a 4-hydrazino-2(1H)-pyridone with 6methoxy-2-tetralone. The reaction is generally performed in - 6 an organic solvent such as an alcohol (e.g. ethanol), at the reflux temperature of the reaction mixture. 6-Methoxytetralone may be obtained by the method described in J. Am. Chem. Soc., 82 . 2573 (1960). 4-Hydrazino-2(1H)-pyridone may be prepared by the method described by C.H. Nguyen and E. Bisagni, Tetrahedron, 42 (8), 2203 (1986).

The pyridobenzindole derivatives of formula (I) may be purified by crystallisation or by chromatography.

The pyridobenzindole derivatives of the invention may be converted into acid addition salts by the action of an acid in an organic solvent. The salt precipitates, where appropriate after concentration of its solution, and may be separated by filtration or after settling has taken place.

Suitable pharmaceutically acceptable salts include the addition salts with inorganic acids, such as hydrochlorides, hydrobromides, sulphates, nitrates and phosphates, or with organic acids, such as acetates, propionates, succinates, maleates, fumarates, methanesulphonates, p-toluenesulphonates, isethionates or substitution derivatives of these compounds.

The pyridobenzindole derivatives according to the invention and their salts can exist in the hydrated state. These hydrated forms also fall within the scope of the present invention.

In addition, when the symbol alk is a branched - 7 alkylene radical, the pyridobenzindole derivatives possess isomeric forms. These isomeric forms also fall within the scope of the invention.

The derivatives of formula (I) are especially 5 advantageous as antitumour agents. Their antitumour properties have been, in particular, demonstrated in vitro at a concentration in the region of 15 to 1.5 gg/disc in the differential cytotoxicity test, according to the technique described by T.H. Corbett et al. Investigational new drug, 4, 207-220 (1986), and in vivo on grafted mouse tumours, more especially on P388 leukaemia, the conpounds have been found to be active at a cbee of 20 mg/kg administered intraperitoneally.

Their toxicity in mice, expressed as their maximum tolerated dose, is greater than 20 and 40 mg/kg administered intraperitoneally.

The pyridobenzindole derivatives of formula (I) in which R is methyl, alk is a linear or branched alkylene radical containing 2 to 4 carbon atoms, Rj is hydrogen or methyl and R2 is hydroxyl, as well as their salts and, where appropriate, their hydrates, are especially advantageous for their antitumour activity. Special interest attaches to l-[3-(dimethylamino)propylamino)-9-hydroxy-5Hpyrido[4,3-b]benz[e]indole, and its salts and its hydrated forms.

The Example which follows illustrates the present invention. - 8 EXAMPLE 1-[3-(Dimethylamino)propylamino]-9-methoxy-5Hpyrido[4,3-b]benz[e]indole (free base) is liberated by excess ammonia from the corresponding dimaleate (1.8 g) and then extracted and dried.

The product thereby obtained is placed in a 250-cc round-bottomed reaction flask, equipped with a stirrer, under argon, with hydrobromic acid (d = 1.47; 47%) (66 cc). This mixture, which has become homogeneous at the boiling point, is heated to reflux for 6 hours and concentrated to dryness under reduced pressure. The solid residue is dissolved in water (200 cc) and alkalinised with 28% ammonia solution (20 cc) which is added dropwise, to form a gummy precipitate.

Ethyl acetate (200 cc) is added to the resulting mixture and the whole is stirred for one hour. The organic phase is separated after settling has taken place and the mother liquors, saturated with sodium chloride, are extracted with ethyl acetate (2 x 100 cc). The organic phase is dried over sodium sulphate, filtered, treated with animal charcoal (5 g) to decolorise it, and then filtered and concentrated to dryness.

The solid residue is taken up in ethanol (40 cc) and treated with maleic acid (2.5 g) dissolved in ethanol (20 cc) at the boiling point. l-[3(Dimethylamino)propylamino]-9-hydroxy-5H-pyrido[4,3-b]benz[e]indole dimaleate, hydrated with 0.25 Η£θ (1.25 g; Yld = 70%), is thereby obtained in the form of microcrystals; - 9 m.p. 195-200°C (decomposition). 1-[3-(Dimethylamino)propylamino]-9-methoxy-5Hpyrido[4,3-b]benz[e]indole dimaleate may be obtained in the following manner: l-Chloro-9-methoxy-5H-pyrido[4,3-b]benz[e]indole (1.8 g) is placed in a 250-cc round-bottomed flask containing 3-(dimethylamino)propylamine (50 cc; large excess) and heated to reflux (150eC) under nitrogen and with stirring for 48 hours (complete disappearance of the chlorinated derivative, checked on a silica plate).

The excess diamine is evaporated off on a water bath under reduced pressure and the residue is taken up in water and then alkalinised with ammonia solution. The solid formed is filtered off, washed with water, taken up in methylene chloride and washed with water (150 cc) and ammonia solution (10 cc) .

After chromatography on alumina and salification with maleic acid under the usual conditions, the expected l-[3-(dimethylamino)propylamino]-9-methoxy-5H20 pyrido[4,3-b]benz[e]indole dimaleate (2.56 g; Y = 69%), m.p. 204-206°C with decomposition, is obtained. l-Chloro-9-methoxy-5H-pyrido[4,3-b]benz[e]indole may be obtained in the following manner: 9-Methoxy-2H,5H-pyrido[4,3-b]benz[e]indol-125 one (4 g), taken up in boiling ethanol and carefully dried, benzyltriethylammonium chloride (14.1 g; 4 equivalents), acetamide (3.6 g; 4 equivalents), acetonitrile (40 cc) and - 10 freshly distilled diethylaniline (9.12 g; 4 equivalents) are introduced into a 1-litre round-bottomed flask equipped with a magnetic stirrer, a dropping funnel and a condenser and maintained under nitrogen.

Distilled phosphorus oxychloride (70 cc) is added gradually via the dropping funnel and an exothermic reaction is observed. The mixture is heated to reflux for 20 hours while, after it has passed through a homogeneous phase, a precipitate appears. The mixture is concentrated to dryness on a water bath heated to 70°C and under reduced pressure (15 mm Hg).

Ice-cold water (300 cc) is added to the residue obtained, and the mixture, stirred well for 2 hours, is heated to 70°C for 20 minutes. It is diluted to 600 cc with water, heated to boiling for 5 minutes and allowed to cool to room temperature with stirring. After cooling, a yellow precipitate is obtained, which is filtered off in the cold state and then washed with cold water. This precipitate is taken up in distilled water (500 cc) and the mixture is alkalinised in the cold state with ammonia solution. The whole is left stirring overnight and the precipitate is filtered off and washed with water. It is recrystallised in alcohol, giving yellow needles of l-chloro-9-methoxy-5Hpyrido[4,3-b]benz[e]indole (2.6 g); m.p. > 260°C; yield 60%. 9-Methoxy-2H,5H-pyrido[4,3-b]benz[e]indol-1one may be obtained in the following manner: N-(2-Oxo-l,2-dihydro-4-pyridyl)-N'-(6-methoxyIE 914072 - 11 1,2,3,4-tetrahydro-2-naphthylidene)hydrazine (18 g) and diphenyl ether (700 cc) are mixed in a 1-litre three-necked flask and the whole is then heated to reflux for 30 minutes while being kept well stirred under nitrogen. The mixture becomes homogeneous and decolorises. Heating is interrupted to allow the mixture to cool to 200°C and check that the starting compound has been completely converted: Merck silica plate, eluent: methylene chloride/ethanol, 8:2 by volume (rf hydrazone - 0.5, rf intermediate compound = 0.8).

While stirring is continued, palladised charcoal (10% Pd) (4 g) suspended in diphenyl ether (20 cc) is added gradually and taking care (foams and evolution of hydrogen), and the new mixture is heated to reflux for 30 minutes (disappearance of the intermediate compound) (rf = 0.35, silica, pure ethyl acetate; expected product: rf = 0.58).

The mixture is then taken up in boiling 2-ethoxyethanol (600 cc), filtered to remove the palladised charcoal and concentrated to dryness. The solid obtained is treated with absolute ethanol (70 cc), stirred for 18 hours, filtered and dried to give yellowish microcrystals (m.p. > 260°C) (11 g; Y = 68%) corresponding to 9-methoxy-2H,5H-pyrido[4,3b)benz[e]indol-l-one.

N-(2-Oxo-l,2-dihydro-4-pyridyl)-N’-6-methoxy1,2,3,4-tetrahydro-2-naphthylidene)hydrazine may be obtained in the following manner: A mixture of 4-hydrazino-2(1H)-pyridone (9.8 g) in absolute ethanol (150 cc) is heated to reflux. To - 12 the solution, which has become homogeneous at the boiling point, 6-methoxy-2-tetralone (16.6 g) is added, and the mixture, which has rapidly become heterogeneous, is heated to reflux for 2 hours (disappearance of the hydrazine checked by TLC on a Merck silica plate, eluent: methylene chloride/ethanol, 1:1 by volume). The precipitate formed is filtered off, taken up in ethanol in which the hydrazone is only sparingly soluble and filtered off in the cold state to give yellow microcrystals of N-(2-oxo-l,2-dihydro-410 pyridyl)-N'-6-methoxy-l,2,3,4-tetrahydro-2naphthylidene)hydrazine (19.3 g; 83%), m.p. 220 - 225°C with decomposition. 4-Hydrazino-2(1H)-pyridone may be obtained according to the method described by E. Bisagni and C.H.

Nguyen, Tetrahedron, 42 . 2303 (1986).

The present invention also provides pharmaceutical compositions containing as active ingredient at least one compound of formula (I), in the pure state (in base or salt form) or in combination with one or more pharmaceutically acceptable diluents or adjuvants. These compositions are preferably used parenterally.

The compositions for parenteral administration can be sterile, aqueous or non-aqueous, solutions, suspensions or emulsions. As a solvent or vehicle, propylene glycol, a polyethylene glycol, vegetable oils, especially olive oil, and injectable organic esters, e.g. ethyl oleate, may be employed. These compositions can also contain - 13 adjuvants, especially wetting, emulsifying or dispersing agents.

Sterilisation may be carried out in several ways, e.g. using a bacteriological filter, by incorporating sterilising agents in the composition, by irradiation or by heating.

The compositions may also be prepared in the form of sterile solid compositions which are dissolved at the time of use in sterile water or any other sterile injectable medium.

In human therapy, the compounds of the present invention are especially useful in the treatment of cancer of the digestive system, lung cancer and testicular or ovarian cancer, as well as in the treatment of cancer of the head and neck.

Generally speaking, the clinician will determine the dosage he considers most suitable in accordance with the age and weight and all other factors specific to the patient to be treated. The preferred method of administration is by the intravenous route. As a guide, the compounds of the invention may be administered intravenously at a dosage of 30 to 200 mg/m2 body surface area per treatment.

The Example which follows illustrates a composition according to the invention: - 14 EXAMPLE: A solution containing hydrated l-[3(dimethylamino)- propylamino]-9-hydroxy-5H-pyrido[4,3-b]benz[e]indole dimaleate (0.5 H2O) (8.54 g) is prepared by dissolving this product in pyrogen-free physiological saline in a sufficient quantity to obtain a total volume of 100 cc.

The solution obtained is distributed aseptically in ampoules at the rate of 2 cc per ampoule. The ampoules are sealed and each contains 100 mg of l-[310 (dimethylamino)propylamino]-9-hydroxy-5H-pyrido[4,3-b]benz[e]indole.

Claims (8)

1. A pyridobenzindole derivative of the formula: 5 in which R represents a hydrogen atom or an alkyl radical containing 1 or 2 carbon atoms, alk represents a linear or branched alkylene radical containing 2 to 4 carbon atoms, Rj represents a hydrogen atom or an alkyl radical containing 1 or 2 carbon atoms, and R 2 represents a hydroxyl or methoxy 10 radical, and its acid addition salts and, where appropriate, its hydrates and its isomeric forms and mixtures thereof.

2. A pyridobenzindole derivative according to claim 1 in which R is methyl, alk is a linear or branched alkylene radical containing 2 to 4 carbon atoms, Rj is 15 hydrogen or methyl, and R 2 is hydroxyl, and its salts and, where appropriate, its hydrates and its isomeric forms and mixtures thereof.

3. l-[3-(Dimethylamino)propylamino]-9hydroxy-5H-pyrido[4,3-b]benz[e]indole, and its salts and its 20 hydrated forms.

4. A process for preparing a pyridobenzIE 914072 - 16 indole derivative according to claim l, which comprises reacting an amine of formula: H 2 N - alk - N(R) 2 in which alk and R are as defined in claim l, with a 5 chlorinated derivative of formula: H3C0 in which R^ is as defined in claim 1, converting the methoxylated product obtained, of formula: H3CO 10 in which Ry is as defined in claim 1, where appropriate, into a 9-hydroxypyrido[4,3-b]benz[e]indole derivative and optionally converting the product obtained into an acid addition salt.

5. A process according to claim 4 substantially as described in the foregoing Example.

6. A pyridobenzindole derivative according to claim l when prepared by the process of claim 4 or 5.

7. A pharmaceutical composition which 5 comprises a pyridobenzindole derivative as claimed in any one of claims 1 to 3 and 6 in combination with a compatible and pharmaceutically acceptable diluent or adjuvant.

8. A composition according to claim 7 substantially as hereinbefore described.