Title of Invention

METAL SALTS OF BENZAZEPINE COMPOUNDS AND PROCESS FOR PREPARATION THEREOF

Abstract

The invention provides a compound of the general formula Wherein R<SUB>I</SUB> is a phenyl-(C<SUB>I</SUB> -C<SUB>6</SUB> )-alkyl group or a I-naphtyl-(C<SUB>1</SUB> -C<SUB>6</SUB> )-alkyl group. R<SUB>2</SUB> is a biolabile ester forming group, As a pharmaceutically acceptable metal salt, characterized in that the salt is selected from the group consisting of the lithium salt, the calcium salt, the magnesium salt and the zinc salt The invention also provides process for preparation of the above compounds

Full Text

The invention relates to a group of novel salts of compounds with the formula (I) and their use in the preparation of pharmaceutical compounds. Benzazepines with the above formula are known from EP 0733642, EP 0830863, WO00/48601 and WO01/03699. EP 0733642 is related to compounds with the formula (I) and their physiologically acceptable salts as such and to the use of the compound in heart insufficiency. EP 0830863, WO00/48601 and WO01/03699 are related to the use of the above compounds in the improvement of gastrointestinal blood flow, in the treatment of hypertension and in the treatment and prophylaxis of cardiac damages induced by adriamycin and comparable anti-cancer drugs, respectively. Preferred benzazepines are the compounds wherein Ri is a phenylethyl group or a 1-naphtylethyl group, R2 and Rs are both hydrogen and wherein R4 is a biolabile ester group. Suitable groups forming biolabile esters include (C1-Ce)-alkyl groups, phenyl or phenyKCi-CeJ-alkyl groups which are optionally substituted in the phenyl ring by (CrCeJ-alkyl or by a (C2-C6)-alkylene chain bonded to two adjacent carbon atoms, dioxolanylmethyl groups which are optionally substituted in the dloxolane ring by (CV Ce)-alkyl or (C2-C6)-alkanoyloxymethyl groups which are optionally substituted on the oxymethyl group by (C1-Ce)-alkyl. Where the group R4 is a by (C1C6lkyl this is preferably an unbranched (Ci-C4)-alkyl group. In the most preferred compounds R4 is ethyl. During further pharmaceutical and clinical development It has appeared that the most preferred compounds have the serious draw-back of being a solid foam In order to ensure a reproducible constant bioavailability of an active ingredient from a solid pharmaceutical dosage form, it is important that a homogeneous and reproducible modification of the active compound is used. Therefore there always exist certain doubts regarding the reproducibility and constantness of bioavailability in compounds that originate from material that normally is not homogeneous, such as a solid foam. It is also obvious that it is very difficult to isolate a solid foam on a commercial scale. Further the compound is very sparsely soluble in water and therefore it is very difficult to prepare a formulation of the compound that can be used for IV administration. Up to the present invention an IV formulation only could be prepared from the corresponding diacid (see example II in EP 0733642). This means that for an IV formulation another compound has to be used than for an oral formulation, which is undesirable for a pharmaceutical compound. During further development it appeared that the sodium- and potassium salt of the mono acid are much better soluble in water, but these salts can also only be isolated as a solid foam. It is the objective of the present invention to provide a salt of the compound with the general formula (I) which should meet the following requirements: a) Easy isolation of the pure solid compound by crystallisation or precipitation on commercial production scale b) Solubility in physiological fluid high enough to prepare an IV formulation c) Solid state properties which allow preparation of a pharmaceutical formulation with standard auxiliary compounds and standard equipment d) Preferably preparation without substantial toss of chiral and chemical purity. This objective can be achieved by preparing the metal salt of the compounds with the general formula (I) as mentioned above wherein the metal ion is a lithium ion or a bivalent metal ton. Preferred bivalent metal salts are calcium, magnesium and zinc salts. Most preferred is the calcium salt. Surprisingly It has appeared that these salts, contrary to the sodium and potassium salts mentioned in EP0733642 have highly desirable properties, as they can be isolated In solid (amorphous) form and have a solubility in an Isotonic fluid of pH 7.4 which is at least a factor of 10 higher than the corresponding acid. Further the bivalent salts can be prepared without racemisation. In another aspect of the present Invention a method Is provided for the preparation of metal salts, preferably Lf or the bivalent Ca2+ Mg2*or Zn2* salts. It has surprisingly been found that lithium salts and bivalent metal salts of the compound of formula I are very soluble in slightly polar aprotic solvents at room temperature, such as cyclohexane, toluene, methyl tertiairy butyl ether and ethyl acetate. The salts of the present invention can be easily obtained by mixing hydroxide or a suitable salt of the desired metal with a solution or slurry of the compound of formula I in one of the above mentioned slightly polar aprotic solvents. Alternatively, when the hydroxide or salt of the desired metal is not soluble enough to start the reaction a small amount of water can be added to the solution or slurry In the organic solvent and the water can be removed by azeotropic destination. In that case an apoiar aprotic solvent which forms an azeotrope with water has to be selected. For metals that have a highly insoluble hydroxide the metal can be added in the form of an ethoxide (e.g. Mg(OEt)2) or as a mixed hydroxide/carbonate (3Zn(OH)2.2ZnC03).The preferred solvent for the above method Is methyl tertiairy methyl ether or ethyl acetate. When the salt has been obtained in solution it can be isolated by first removing the water mat is still available by azeotropic distillation, followed by mixing with a precipitant. A precipitant is defined as a second liquid that is added to a solution to reduce the solubility of the dissolved compound, causing its precipitation/crystallization and maximizing the yield of product. It is necessary for the two liquids (the original solvent and the added precipitant) to be completely miscible with one another in all proportions. (This approach is also used to reduce the solubility of an inorganic salt in aqueous solution by the addition of a water-miscibie organic solvent (ALFASSI Z.B. et al., AlChE J. 1984,30, 874-6; MYDLARZ J. et al., J. Chem. Eng. Data 1989,34.124-6; MULLIN J.W. etal., Chem. Eng. Process. 1989, 26, 93-9). Examples of precipitant in the framework of this invention are linear hydrocarbons. Preferred precipitant are linear C4-C10 hydrocarbons. The most preferred precipitant is n-hexane. As in all cases the salt is isolated In the form of a non-crystalline precipitate, which appears in all cases to be homogeneous, it is sometimes desirable to have a real crystallisation step in order to improve the purity of the active compound whichhas to meet strict requirements. It has surprisingly been found that the S-a-methylbenzyl amine salt of the compound of formula I is extremely suitable in the purification of these compounds, as said salt is crystalline and can be easily recrystallised in high yields from organic solvents, preferably alcohols such as ethanol or isopropyl alcohol. Therefore the present invention is also related to S-a-methylbenzyiamine salts of the compounds of formula I. Said salts are only suitable as intermediates In a purification step, as the S-a-methyibenzylamine appears to be too toxic to be used. The S-a-methylbenzylarntne salts of the compounds of formula I can be prepared by adding S-a-methylbenzylamine to a solution of the compound of formula I in ethanol or isopropanol or another suitable alcohol. The salt will crystallize from that solution upon standing and cooling (dependent on concentration) The pharmaceutical^ acceptable salts of the present invention can be formulated according to state-of-the art formulation processes. Customary formulations can be used, such as, e.g. tablets, capsules or suppositories. These pharmaceutical formulations can be produced by known methods such as direct compression, granulation, extrusion, moulding using conventional solid excipients such as fillers e.g. celluloses, lactoses and starches, binders e.g. celluloses and polyvinylpyrrolidon (pvp), desintegrants e.g. starches and cross-linked pvp, glidiants e.g. colloidal silica, lubricants e.g magnesium stearate or conventional liquid and semi-solid excipients such as poly ethylene glycols, caster oil derivates, triglycerides and paraffins. Additionally preservatives e.g. parabens and emulsifiers e.g. poly sorbates can be added. The pharmaceutical^ acceptable salts of the present invention are suitable as medicaments for larger mammals, especially humans, for in the treatment of heart failure and for promoting diuresis/natriuresis, especially In patients suffering from heart failure, for the improvement of gastrointestinal blood flow, in the treatment of hypertension and in the treatment and prophylaxis of cardiac damages induced by adriamycin and comparable anti-cancer drugs. For this purpose the compounds of the invention can be used In medicinal forms which can be administered parenteral^, especially i.v., orally or as suppository. The doses to be used may vary individually and vary with the nature of the condition to be treated, the particular substance used and the mode of administration. Medicinal forms with an active substance content of from 1 to 800 mg per individual dose are generally suitable for administration to larger mammals, especially humans. The following examples are only intended to further illustrate the invention, in more detail, and therefore these example are not deemed to restrict the scope of the invention in any way. EXAMPLES. Example 1. General procedure for the preparation of metal salts of compounds of formula 1. About 15 mmole of the active substance in the acid form was solved or suspended in 40 ml of a slightly polar aprotlc solvent. A solution of about 1.2 equivalents of the metal reagent in water or in the same solvent as the active compound was added. In some cases water had to be added to start the reaction. The water was removed by azeotropic distillation. When the metal reagent was not a hydroxide or an ethoxide, the solvent was totally removed, followed by re-dissolution in 40 to 160 ml of the original slighly polar aprotic solvent, followed by filtration in order to remove unreacted metal reagent and optional other salts formed. The filtered solution was dosed to hexane and, when a solid product was formed, it was collected on a filter. When a tar or oil was formed the largest part of the solvent was decanted and the remaining solvent was evaporated to yield a solid foam. The properties of the salts prepared are summarised in Table 2. The compound content was determined with an HPLC- method (MACHEREY-NAGEL Nudeosil 100-5 C18-HD as a column, using a gradient system starting from 5% B and ending with 100% B, with a phosphoric acid buffer of pH=5.1 as eluent A and eluent B being acetonitril mixed with 10% eluent A). The metal content was determined by a complexometric titration with ethylenediamine-tetra-acetic acid disodiumsalt solution for Calcium and with Atomic Emission Spectroscopy (AES) for all other metals. From Table 2 it appears that the Li, Ca, Mg and Zn salts, which were isolated as a solid powder are soluble in slightly polar aprotic solvents. Examples of these solvents are ethyl acetate, toluene, cyclohexane and methyl t-butyt ether. The compounds are also soluble in polar aprotic solvents such as THF, acetone, acetonitril, DMF and DMSO. The metal contents found in the salt are somewhat higher than the theoretical amounts, but this is normal in these types of work-up and analyses. During salt formation with the strongly basic monovalent hydroxides degradation of the active substance occurs, leading to a low compound content in the final salt. Example 2. Preparation of the S-o-methylbenzylamine salt of 1H-1-Benz-azepine-1-acetic add, 3-[[[14(2R)-2^ethoxycarbcflyl)-4-prienytbutyl]-cyclo-pentyqcarbonyl]amino]^,3A54etrahydro. 18 g of 1H-1-Benzazepine~1-acetic acid, 3^[[1H(2R)-2Kethoxycarbonyl)-4-phenyi- butyl]cydopentyQcarbonyfJarnino}-2l3,4,5-tetrahydro-2-oxo-, (3S> were solved in 90 ml of absolute ethanol. 4.1 g S-methylbenzyl amine was added at 20-25°C. The spontaneously formed crystal slurry was heated to 40°C and stirred for one hour. After cooling to 0-5°C and additional stirring for 4 hours the crystals were collected by filtration, washed with 40 ml chilled absolute ethanol and dried at 45 "C in a vacuQm oven. 19 g of the S-methylbenzyl amine salt of 1H-1-Benzazepine-1-acetic acid, 3-[[[1-[(2R)-2- 2,3,4,5-tetrahydro-2-oxo-, (3S)- were yielded as first crop. Example 3. Preparation of the calcium salt of 1H-1-Benzazepine-1-acetic acid, 3-[[[1-[(2R)-2-(ethoxycarbonyl)-4-phenylbutylJcyclopentyl]carbonylJamlno]-2,3,4,5-tetrahydro-2-oxo-, (38}-. To a solution of 30 g of the S-a-methylbenzylamlne salt of 1H-1-Benzazeplne-1-acetic add, 3-[QH(2R)-2-(etrK>xycarbonyl)-4^heny»b^ amino^.SAS-tetrahydro^-oxo-, (3S)- in 120 ml of methyl terHairy butyl ether (MTBE), 100 ml of a 1M aqueous solution of hydrochloric acid was added and the resulting mixture was stirred for 10 minutes. The layers were separated and the organic layer was washed at least three times with 15 mi of water until the pH was higher than 5. An amount of 2 g Ca(OH)2 95% was added and the mixture was heated to 55°C under reflux. When the amount of suspension was not significantly diminished after 30 minutes, an amount of 0.5 ml of water was added. The mixture was refluxed via a water trap (Dean-Stark apparatus) during 2 hours. After 2 hours the distillate was completely clear and the reaction mixture was a little bit turbid. The mixture was cooled down to 30-35°C and dosed in 30 minutes via an in-fine filter to 240 ml of hexane. The solid product was isolated by filtration and washed with 50 ml of hexane. After drying 25.6 g of an off-white free flowing powder was obtained. Example 4. Preparation of the S-a-methylbenzylamlne salt of Compound II * 1H-1-Benzazepine-1 -acetic acid, 3-t[[1-[2-(ethoxycarbonyl)-4-{1-naphthalenyl)-butyf]cyclci>entyl]carbonyllamlnol-2,3,4,5-tetrahydro-oxo-,[S-(R*,S*)l-. 21 g of Compound II = 1H-1-Benzazepine-1-acetic acid, 3-[[[1-[2-(ethoxycarbonyl)-4- (1-naphthalenyl)butyl]cyctopentyflcarbonyq^ was solved in 190 ml of MTBE. 45 ml of ethanol and 4.5 g S-o>methylbertzyl amine was added. After storage for 4 days at 4*C and stirring once a day the cristate were collected by filtration, washed with 80 ml MTBE and dried at 45 °C in a vacuum oven. 19 g of the S-methylbenzyl amine salt of Compound II = 1H-1-Benzazepine-1-acetic add, 3-[[[1-[2-(ethoxycarbonylM-(1-naphthalenyi)buty^ amlno]-2,3,4,5-tetrahydro-oxo-,[S-(R*,S*)]-. were yielded as first crop. Example 5. Preparation of the calcium salt of 1H-1-Benzazepine-1-acetic acid, 3-{Q1-[2^ethoxy(»ri)onyl)^1-naphthalenyl)4>iityncyclope^lJcarbonyrj- amlnoJ-2,3,4,5-*etrahydro-oxo-,[S-(R*,S*)]-. To a heterogeneous mixture of 10 g of the S-a-mettiyttjenzylamine salt of 1H-1-Benzazepine-1-acetic acid, 3-[[[H2-{etrK>xycarbcf)yl)4-(lHiapht)atenyl)-butyrj-cydopentyl]carbciiyl]amirK>]-2,3,4,5-tetrahydro-oxo-,[S-(R*,S*)]- in 80 ml of methyl tertiairy butyl ether (MTBE) and 60 ml of water, 4.4 ml of a 36% aqueous solution of hydrochloric acid was added in 15 minutes under stirring and the resulting mixture was stirred for 1.5 hours at room temperature. The layers were separated and the organic layer was washed two times with 50 ml of water. The organic layer was concentrated to an oil, 15 ml of ethyl acetate was added and the solution obtained was again concentrated to art oil. The oil was solved again in 80 ml of ethyl acetate and 2 ml of water was added. An amount of 0.56 g Ca(OH)2 95% was added and the mixture was refluxed during 4 hours via a water trap (Dean-Stark apparatus). The solution was filtered and reduced in volume to 40 ml. The solution was cooled down to 30-35°C and dosed in 30 minutes to 250 ml of cold hexane (10°C) and stirred for an additional 30 minutes at 10°C.. The solid product was isolated by filtration and washed twice with 10 ml of hexane. After drying under vacuum (18 hours, 50°C, 120 mbar) 7.4 g of free flowing powder was obtained. 1H-NMR: 5 = 7.99 (1H, broad doublet, J=8), 7.88 (1H, dd, J=1.5 and 8), 7.73 (1H, broad doublet. J=8), 7.56-7.44 (2H, m), 7.37 (1H, t, J=8), -7.36 (NH, d, J=8), 7.31 (1H. dd, J=1.5 and 8), 7.29 (1H, d, J=8), 7.24 (1H, triple doublet, J=1.5, 8, 8), 7.21 (1H, dd, J=1.5 and 8), 7.13 (1H, triple doublet, J=1.5, 8, 8), 4.48(1H, d, J=16), 4.23 (1H, double triplet, J=8, 8, 12), 4.14-3.99 (3H, m), 3.56 (1H, triple doublet, J=8, 13, 13), 3.02-2.96 (2H, m), 2.5-2.34 We Claim, 1. A compound of the general formula (1) wherein R1 is a phenyl-(C1-C6)-alkyl group or a l-naphtyl-(C1-C6)-alkyl group. R2 is a biolabile ester forming group, as a pharmaceutical ly acceptable metal salt, characterized in that the salt is selected from the group consisting of the lithium salt, the calcium salt, the magnesium salt and the zinc salt 2. Salt of the compound with the general formula (1) as claimed in claim I, wherein, R2 has the same meaning as in claim 1, and wherein R1 is a phenylethyl group or a 1- naphtylethyl group. 3. Salt of the compound with the general formula (1) as claimed in claims 1-2, wherein R2 is an ethyl group. 4. A calcium salt as claimed in claims 1-3. 5. A method of preparing a salt according to claims 1-4, characterized in that a solution or slurry of the hydroxide of said metal is mixed with an solution or slurry of said compound of formula 1 in a slightly polar aprotic solvent to yield a homogeneous solution of the salt in said slightly polar aprotic solvent. 6. The method as claimed in claim 5, wherein said slightly polar aprotic solvent is methyl tertiary butyl ether or ethyl acetate. 7. The method as claimed in claims 5 and 6, wherein the salt is isolated in solid form by (i) optionally azeotropic removal of water, followed by (ii) crystallization or precipitation of the salt by mixing of the solution in the slightly polar aprotic solvent with an precipitant. 8. The method as claimed in claim 7, wherein said precipitant is a linear (C4-C10)- hydrocarbon. 9. The method as claimed in claim 8, wherein said precipitant is n-hexane. 10. A pharmaceutical composition containing at least one salt as claimed in claims 1-4 as an active component. 11. A method of preparing a composition as claimed in claim 10, wherein a salt as claimed in claims 1-4 is brought into a form suitable for administration.

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1519-chenp-2004 abstract duplicate.pdf

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1519-chenp-2004 correspondence others.pdf

1519-chenp-2004 correspondence po.pdf

1519-chenp-2004 description (complete) duplicate.pdf

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1519-chenp-2004 petition.pdf