WO1996031466A1

WO1996031466A1 - New ethanolamine derivatives

Info

Publication number: WO1996031466A1
Application number: PCT/EP1996/001305
Authority: WO
Inventors: Carles Puig Duran; Ferrán PUJOL NOGUERA; Maria Isabel Crespo Crespo; Jacinto Moragues Mauri
Original assignee: Laboratorios Almirall, S.A.
Priority date: 1995-04-03
Filing date: 1996-03-25
Publication date: 1996-10-10
Also published as: AU5148796A; UY24199A1; IL117784A0; ZA962597B

Abstract

A compound which is an ethanolamine derivative of formula (I), wherein R1 is a pyridyl or NR2R3 group, wherein R2 is hydrogen or a C¿1?-C4 alkyl or methanesulphonyl group and R?3¿ is a C¿2?-C4 alkanoyl group, an unsubstituted phenyl group or a phenyl group substituted by a carbamoyl group; m is from 4 to 8; and n is 2 or 3; or a pharmacologically acceptable salt thereof, has agonist activity on the adrenergic β-receptors of the bronchus.

Description

NEW ETHANOLAMINE DERIVATIVES

This invention relates to new therapeutically useful ethanolamine derivatives, to processes for their preparation and to pharmaceutical compositions containing them.

It is known that ethanolamine derivatives are compounds in which the most important characteristic is to possess a selective agonist activity on the adrenergic /6₂-receptors of the bronchus. Such compounds are useful as bronchodilator agents.

In DE-A-3,414,752, DE-A-3,704,223 and DE-A-4, 028, 398 ethanolamine derivatives of general formulae:

are respectively disclosed.

We have now found that the simultaneous presence of a chlorine atom and a cyano group on the phenyl ring, and a long chain substituent attached to the NH group, provides new compounds with improved selectivity and rapid and prolonged action.

Accordingly, the present invention provides a compound which is an ethanolamine derivative of formula (I) :

wherein:

R¹ is a pyridyl or NR²R³ group, wherein R² is hydrogen or a

C_JL-C._! alkyl or methanesulphonyl group and R³ is a C₂-C₄ alkanoyl group, an unsubstituted phenyl group or a phenyl group substituted by a carbamoyl group; m is from 4 to 8; and n is 2 or 3; or a pharmacologically acceptable salt thereof.

The present invention also provides a process for preparing a compound as defined above which comprises reducing an i ino derivative of formula (V) :

wherein R¹, m and n are as defined above with a reducing agent and, if desired, converting the thus-formed derivative of formula (I) into a pharmacologically acceptable salt thereof. The present invention additionally provides a process for preparing a compound as defined above which comprises reacting a 2-bromoethanol derivative of formula (VI) :

wherein R⁴ is a protecting group with an amine of formula (IV) :

H₂N-(CH₂)_n-0-(CH)_n-R¹ (IV)

wherein R¹, m and n are as defined above to prepare a compound of formula (VII) :

wherein R¹, R⁴, m and n are as defined above, followed by deprotection of the hydroxy group and, if desired, converting the thus-formed derivative of formula (I) into a pharmacological acceptable salt thereof.

The present invention further provides a compound as defined above for use in a method of treatment of the human or animal body by therapy, especially for use as an agonist on the adrenergic /8-receptors of the bronchus.

The present invention also provides use of a compound as defined above in the manufacture of a composition for use as an agonist on the adrenergic j3₂-receptors of the bronchus.

Ethanolamine derivatives of formula (I) exhibit optical isomerism and the isomers are within the scope of the invention.

Preferred compounds of general formula (I) are those wherein R¹ is a pyridyl group, R¹ is a NR²R³ group wherein R² is hydrogen and R³ is a phenyl group substituted in the 4-position by a carbamoyl group (i.e. R¹ is a

4-carbamoylphenylamino group), m is 6 and/or n is 2; and pharmacologically acceptable salts thereof.

Of outstanding interest are : 4- [2- [6- [2- (4-amino-3-chloro-5-cyanophenyl) -2- hydroxyethylamino]hexyloxy] ethylamino]benzamide, 2-amino-3-chloro-5- [l-hydroxy-2- [6- (2-pyrid-2- ylethoxy)hexylamino] ethyl]benzonitrile, and (-) - (R) -2-amino-3-chloro-5- [l-hydroxy-2- [6- (2-pyrid-2- ylethoxy)hexylamino] ethyl]benzonitrile; and pharmacologically acceptable salts thereof.

The compounds of the invention may, for example, be prepared from 4-amino-3-chloro-5-cyanoacetophenone of formula (II) :

by oxidation, preferably with selenium oxide in the presence of a silica gel in a solvent such as dioxane-water or tetrahydrofuran-water, preferably at a temperature of 50°C to the boiling point of the solvent. In the reaction, the aldehyde of formula (III) is first formed in the reaction mixture:

The corresponding amine of formula (IV) is added:

H₂N-(CH₂)_m-0-(CH₂)_n-R¹ (IV)

wherein R¹, m and n are as defined above, preferably at a temperature of 15°C to 35°C, to give the imino derivative of formula (V) :

wherein R¹, m and n are as defined above. The imino derivative of formula (V) is then reduced with a reducing agent, such as sodium borohydride, preferably at a temperature of 10°C to 25°C, to give the ethanolamine derivative of formula (I) .

The compounds of the invention may, for example, also be prepared by reacting a 2-bromoethanol derivative of formula (VI) :

wherein R* is a protecting group, preferably a t-butyldimethylsilyl group, with an amine of formula (IV) to give the intermediate compound of formula (VII) :

wherein R¹, R⁴, m and n are as defined above, and further deprotection of the hydroxy group.

The reaction between the 2-bromoethanol derivative of formula (VI) and the amine of formula (IV) is preferably carried out in an organic solvent as dioxane, tetrahydrofuran, acetonitrile, methyl isobutyl ketone or N,N-dimethylformamide, at a temperature of from 70°C to

125°C, in the presence of sodium or potassium iodide and an organic or inorganic base such as diisopropylethylamine or sodium or potassium carbonate.

The deprotection reaction of the compound of formula (VII) to obtain the ethanolamine derivative of formula (I) is preferably carried out in a solvent such as tetrahydrofuran, dioxane or N,N-dimethylformamide in the presence of an alkaline or tetraalkylammonium fluoride, preferably tetrabutylammonium fluoride, at a temperature of from 10°C to 40°C.

The -CHOH- group in the derivative of formula (I) is a chiral centre and, for this reason, the ethanolamine derivatives of the present invention have (R) - and (S) - isomers. These isomers can be prepared from the corresponding (R) - or (S) -bromethanol derivative of formula (VI) , by reaction with an amine of formula (IV) and deprotection as mentioned above. This process is carried out under the same conditions that are described for the preparation of ethanolamine derivatives of formula (I) in their racemic form.

The intermediates of formulae (II) and (IV) used in the preparation of the compounds of the invention are known compounds and are described, for example, in Arzneim. Forsch. 34 (II), p. 1612 (1984), DE-A-3,704,223 and EP-A-0,460,924.

The intermediates of formulae (VI) and their corresponding (R) - and (S) -isomers may be prepared by methods disclosed in the literature in, for example, G. Kruger et al. , Arzneim. Forsch. 34 (II), p. 1612 (1984) and EP-A-0,460,924.

The ethanolamine derivatives of formula (I) may be converted by known methods into pharmacologically acceptable salts such as acid addition salts with acids by appropriate methods with acids in appropriate solvents, for example alcohols, tetrahydrofuran or acetone. Suitable acid addition salts are those derived from organic acids, for example, fumarates, acetates, malates or benzenesulphonates. The following biological tests and data further illustrate this invention.

1. Binding to rat cerebellum 3₇-adrenoreceptors

Assays were performed essentially as described by Rimele et al. (J. Pharmacol. Exp. Ther. 239: 1-8 (1986) . Varying amounts of compounds to be tested were added to 1 ml final volume reaction mixtures that included 90 μg of rat cerebellum membrane protein, 0.5 nM

³H-dihydroalprenolol, 5 mM MgCl₂ and 50 mM Tris HC1 buffer, pH 7.5. After incubation at 25°C for 45 minutes, samples were filtered under reduced pressure using glass fibre filters. The filters were washed with ice-cold buffer and dried. Non-specific binding was defined as that obtained in the presence of 50 μK isoprenaline. Trapped radioactivity was quantified using a beta counter. Displacement curves were constructed, and the concentration displacing 50% of radioligand was calculated for each tested compound using non-linear regression. For each drug concentration, data from at least four different measurements was averaged.

2. Relaxant activity in guinea-pig isolated tracheal rings (spontaneous tone) .

Male Dunkin-Hartley guinea-pigs of weight range 400- 600g were fasted overnight but with free access to water for 16 hours prior to experimentation. Animals were then killed by cranial percussion and the trachea dissected free and placed into Krebs solution at 4°C. The trachea were cut into preparations consisting of two rings which were then cut through the cartilaginous zones. The preparations were suspended in 30 ml organ baths containing Krebs solution at 37°C gassed with 5% C0₂ in 0₂. These were allowed at least 1 hour to equilibrate during which time the resting tension was maintained at 1 g. A control response to isoprenaline (lxlO^"7 M) was then obtained, to indicate the maximum relaxation possible in this tissue. The tissues were then washed and allowed 30 minutes to reequilibrate prior to adding one of the drugs under study using a cumulative concentration procedure. Responses were allowed to stabilise (usually within 15 minutes of drug addition) .

Tension was recorded using isometric transducers (Letica TR1 010) onto a Letica polygraph (model 4000) . Changes in tension were measured considering the relaxation obtained by 10^"7 M isoprenaline as 100%.

3. Effects on histamine induced bronchoconstriction in anaesthetized guinea-pigs

Male Dunkin-Hartley guinea-pigs (400-600g) were anaesthetized with pentobarbital sodium (90 mg/kg i.p.) and the trachea were cannulated for recording of the intrapulmonary pressure (Konzett, H., Rδssler, R. (1940), Naunyn -Sαhmied. Arch . Pharmacol . 195, 71-74) . A minimum of five animals per group were used.

Following one hour stabilization, several bolus of histamine (4 μg/kg i.v.) were administered to obtain stable bronchoconstrictive responses (reflected by increases in pulmonary pressure) . Then, compounds were administered intravenously at doses in the range of 0.01 to 10 μg/kg, each dose followed by a histamine injection. The inhibition effects on histamine induced bronchoconstriction were evaluated in terms of percentage of change from the initial response. The ED₅₀ (dose that produces fifty per cent inhibition) was calculated for each compound.

4. Onset and duration of action upon histamine induced bronchospasm in guinea-pigs. Administration of compounds by aerosol route.

Male Dunkin-Hartley guinea-pigs (300-500 g) fasted overnight were used. Animals, in groups of five, were transferred to a perspex box (47 x 27 x 27 cm) , provided with a connection to a filtered air-flow, following a previously established treatment randomisation schedule. Either compounds or saline were then aerosalised into the box using a DeVilbiss ULTRA-ΝEB 2000 nebuliser, during one minute, at a concentration of 0.1 mg/ml. At the same time (1 minute), 5 minutes, 1, 2, 4 and 6 hours (duration of action) after treatment, a physiological saline solution of histamine (250 μg/ml) was nebulized, and the presence or absence of bronchospasm was recorded during the following five minutes. Finally, the percentage of animals without bronchospasm was calculated as an index of protection. Five to 15 animals per group were used.

The results of the above tests are shown in Table 1:

Table 1

(1) Compound disclosed in DE-A-3,414,752 (Example 2)

(2) " ^■ - EP-A-0,460,924 (Examples 1, 3, 4 and 5)

(3) See structures in Table 2.

As can be seen from Table 1, the new ethanolamine derivatives of the present invention are more potent than known compounds, with rapid and long duration of action, and an advantageous profile. The compounds of the present invention exhibit pharmacological properties useful in the treatment of reversible airways obstruction such as asthma and chronic bronchitis. They are also indicated in the treatment of allergic and inflammatory diseases, depression, glaucoma, congestive heart failure, premature labour and in disturbances in which it is an advantage to decrease the gastric acidity.

The pharmaceutical compositions of the present invention comprise, as active ingredient, at least one compound of formula (I) , in association with a pharmaceutically acceptable carrier or diluent. Preferably the compositions are in a form suitable for inhalation, oral, rectal, transdermal, bucal, nasal or parenteral administration. The pharmaceutically-acceptable carriers or diluents which are admixed with the active compound or compounds to form the compositions of this invention are well known per se and the actual excipients used depend inter alia on the intended method of administration of the compositions. Compositions of this invention are preferably adapted for administration per inhalation. Compositions for inhalation administration may be in the form of solutions, suspensions or micronized powder, contained in an appropriate inhaler. The compositions for oral administration may take the form of tablets, capsules, lozenges or effervescent granules or liquid preparations such as elixirs, syrups or suspensions, all containing one or more compounds of the invention. Such preparations may be made by methods well known in the art, for instance by mixing the derivative of formula (I) or salt thereof with the pharmaceutically acceptable carrier or diluent.

The diluents which may be used in the preparation of the compositions include those liquid and solid diluents which are compatible with the active ingredient, together with colouring or flavouring agents if desired.

The liquid compositions adapted for oral use may be in the form of solutions, suspensions or aerosols. The solutions may be aqueous or aqueous-alcoholic solutions of a soluble compound in association with, for example, sucrose or sorbitol to form a syrup. The suspensions may comprise an insoluble or microencapsulated form of an active compound of the invention in association with water and other acceptable solvents together with a suspending agent or flavouring agent.

Compositions for parenteral injection may be prepared from the soluble compound, which may or may not be freeze-dried and which may be dissolved in water or an appropriate parenteral injection fluid. In human therapy, the doses of the ethanolamine derivative of formula (I) or salt thereof depend on the desired effect and duration of the treatment; adult doses are generally between 0.005 mg and 100 mg per day. In general, the physician will decide the posology taking into account the age and weight of the patient being treated. The present invention also provides a method of treatment of reversible airways obstruction, allergic and inflammatory diseases, depression, glaucoma, congestive heart failure, premature labour and disturbances in which it is an advantage to decrease the gastric acidity, which method comprises administering to a subject in need of such treatment an effective amount of a derivative of formula (I) or a pharmacologically acceptable salt thereof. The following Examples further illustrate the invention. EXAMPLE 1

A mixture of 4-amino-3-chloro-5-cyanoacetophenone (3.12g; 0.016 moles), selenium oxide (2.0 g; 0.018 moles) and silica gel (1.5 g) in dioxane (32 ml) and water (2.0 ml) was boiled under reflux for 4 hours. The insoluble solid was filtered off and 4- [2- (6- a inohexyloxy) ethylamino]benzamide (3.9 g; 0.014 moles) was added to the filtrate at room temperature. After stirring at the same temperature for one hour, the mixture was diluted with ethanol (80 ml), and sodium borohydride (2.3 g; 0.06 moles) was slowly added at a temperature below 10°C. The resulting mixture was stirred for 15 hours at room temperature, the solvent removed under reduced pressure, the residue treated with a mixture of diethyl ether-water and decanted. The organic solution was washed with water, dried (Na₂S0₄) and the solvent removed in vacuo. The obtained residue was purified by silica gel column chromatography with methylene chloride-methanol- ammonium hydroxide 40:2.5:0.1 as eluent. 4- [2- [6- [2- (4- amino-3-chloro-5-cyanophenyl) -2- hydroxyethylamino]hexyloxy] ethylamino]benzamide was obtained which was recrystallized from ethanol (0.7 g) ; melting point 156-158°C (Compound 3 in Table 2) .

EXAMPLE 2 a) To a solution of (-) - (R) -2-amino-3-chloro-5- (2- bromo-1-hydroxyethyl) benzonitrile (9.21 g; 0.0334 moles) and imidazole (2.48 g; 0.036 moles) in anhydrous N,N-dimethylformamide (14 ml) , another solution of t-butyldimethylsilyl chloride (7.55 g; 0.05 moles) in anhydrous N,N-dimethylformamide (35 ml) was slowly added, under a nitrogen atmosphere and at a temperature below 10°C. After stirring for 14 hours at room temperature, n-hexane (380 ml) and water (380 ml) were added, decanted and the aqueous layer washed with n-hexane (2 x 90 ml) . The organic extracts were washed with water (4 x 90 ml) , dried and the solvent removed in vacuo at a temperature below 40°C. (-) - (R) -2-amino-3-chloro-5- (2-bromo-l-t- butyldimethylsilyloxy ethyl) benzonitrile was obtained as an oil (11.0 g) . b) A solution of the above compound (11.0 g; 0.0282 moles) in acetonitrile (75 ml) was added to another solution of 6- [2- (2-pyridinyl) ethoxy] hexanamine (9.42 g; 0.042 moles), N,N-diisopropylethylamine (10.21 ml) and sodium iodide (4.3 g) in acetonitrile (75 ml) . The resulting mixture was boiled under reflux and a nitrogen atmosphere for 48 hours, the solvent removed in vacuo, the residue treated with methylene chloride-water and decanted. The organic solution was washed with water, dried (MgS0₄) and the solvent removed under reduced pressure to give an oil (18.7 g) . This compound was dissolved in tetrahydrofuran (145 ml) and tetrabutylammonium fluoride trihydrate (17.7 g) was added. After stirring for 24 hours at room temperature the solvent was removed in vacuo, the residue treated with ethyl acetate-water and decanted. The organic solution was washed with water, dried (MgS0₄) and evaporated under reduced pressure to give 20.3 g of dry compound which was purified by silica gel column chromatography with methylene chloride-methanol-ammonium hydroxide 40:2.5:0.1 as eluent. Pure(-) - (R) -2-amino-3- chloro-5- [l-hydroxy-2- [6- (2-pyrid-2-ylethoxy) hexylamino] ethyl] benzonitrile was obtained as an oil (7.6 g) which was salified with fumaric acid (1.06 g) in ethanol. The resulting fumarate (3.3 g) was recrystallized from ethanol-methanol to give 3.0 g, m.p. 156-158°C. (Compound 2 in Table 2) .

The ethanolamine derivatives of formula (I) in Table 2 were prepared according to the processes disclosed in these Examples but with the appropriate starting materials. Table 2

EXAMPLE 3

10,000 inhalation-flasks each containing 25 mg of micronised (-) - (R) -2-amino-3-chloro-5- [l-hydroxy-2- [6- (2- pyrid-2-ylethoxy)hexylamino] ethyl]benzonitrile (active compound) were prepared as follows :

Active compound 250 g Sorbitan trioleate 5 g propellent q.s. 200 1

Procedure A macrocrystalline suspension prepared with these ingredients was introduced in the inhalation flasks at a volume of 20 ml per flask with a filling machine. The flasks were furnished with an appropriate valve which releases 0.1 ml of suspension for each activation (0.125 mg active compound) .

EXAMPLE 4

50,000 capsules each containing 2 mg of micronised 2-amino-3-chloro-5- [l-hydroxy-2- [6- (2-pyrid-2-ylethoxy) hexylamino] ethyl]benzonitrile (active ingredient) were prepared from the following formulation:

Active compound 100 g

Lactose monohydrate 12 kg Corn starch 1.2 kg

Colloidal silicon dioxide 0.12 kg

Magnesium stearate 0.25 kg

Procedure

The above ingredients were sieved through a 60 mesh sieve, then mixed in a suitable mixer and filled into 50,000 gelatine capsules.

Claims

1. A compound which is an ethanolamine derivative of formula (I) :

wherein: R¹ is a pyridyl or NRR³ group, wherein R² is hydrogen or a C.-C₄ alkyl or methanesulphonyl group and R³ is a C₂-C₄ alkanoyl group, an unsubstituted phenyl group or a phenyl group substituted by a carbamoyl group; m is from 4 to 8; and n is 2 or 3; or a pharmacologically acceptable salt thereof.

2. A compound according to claim 1 in which R¹ is a pyridyl group.

3. A compound according to claim 1 wherein R¹ is a NR²R³ group wherein R² is hydrogen and R³ is a phenyl group substituted in the 4-position by a carbamoyl group.

4. A compound according to claim 1 wherein m is 6.

5. A compound according to claim 1 wherein n is 2.

6. A compound according to claim 1 which is in the form of a fumarate, acetate, malate or benzenesulphonate acid addition salt.

7. A compound which is:

4- [2- [6- [2- (4-amino-3-chloro-5-cyanophenyl) -2- hydroxyethylamino]hexyloxy] ethylamino]benzamide, 2-amino-3-chloro-5- [l-hydroxy-2- [6- (2-pyrid-2- ylethoxy)hexylamino] ethyl]benzonitrile, (-) - (R) -2-amino-3-chloro-5- [l-hydroxy-2- [6- (2-pyrid-2- ylethoxy)hexylamino] ethyl]benzonitrile; or a pharmacologically acceptable salt thereof.

8. A process for preparing a compound as defined in claim 1 which comprises reducing an imino derivative of formula (V) :

wherein R¹, m and n are as defined in claim 1 with a reducing agent and, if desired, converting the thus-formed derivative of formula (I) into a pharmacologically acceptable salt thereof.

9. A process according to claim 8 wherein the reducing agent is sodium borohydride.

10. A process according to claim 8 wherein the compound of formula (V) has been prepared by reacting a compound of formula (III) :

with an amine of formula (IV) :

H_jN- CH^.-O-fCH^.-R¹ (IV)

wherein R¹, m and n are as defined in claim 8.

11. A process for preparing a compound as defined in claim 1 which comprises reacting a 2-bromoethanol derivative of formula (VI) :

wherein R⁴ is a protecting group with an amine of formula (IV) as defined in claim 10 to prepare a compound of formula (VII) :

wherein R⁴ is as defined above and R¹, m and n are as defined in claim 8, followed by deprotection of the hydroxy group and, if desired, converting the thus-formed derivative of formula (I) into a pharmacological acceptable salt thereof.

12. A pharmaceutical composition comprising a compound as defined in claim 1 and a pharmaceutically acceptable carrier or diluent.

13. A compound as defined in claim 1 for use in a method of treatment of the human or animal body by therapy.

14. A compound according to claim 1 for use as an agonist on the adrenergic 3₂-receptors of the bronchus.

15. Use of a compound as defined in claim 1 in the manufacture of a composition for use as an agonist on the adrenergic β₂-receptors of the bronchus.