FI76560C - FOR EXAMINATION OF PHARMACEUTICAL PRODUCTS 1- / 2 - / (1-CARBETOXY-3-PHENYLPROPYL) AMINO / -1-OXOPROPYL / -OCTAHYDRO-1H-INDOL-2-CARBOXYL SYRA. - Google Patents

Description

76560

Process for the preparation of a pharmaceutically acceptable 1- [2 - [(1-carboxyethoxy-3-phenylpropyl) amino] -1-oxopropyl] -octahydro-1H-indole-2-carboxylic acid - [(1-Carboethoxy-3-phenylpropyl) amino] -1-oxopropyl-1-octahydro-1H-indole-2-carboxylic acid (Separated from patent application No. 81 0971)

The compound N- (1-ethoxycarbonyl-3-phenylpropyl) -L-alanyl-L-proline (enalapril) is a known ACE inhibitor.

The present invention relates to a process for the preparation of a pharmaceutically acceptable 1- [2 - [(1-carbethoxy-3-phenylpropyl) amino] -1-oxopropyl] octahydro-1H-indole-2-carboxylic acid of formula II

CH 2 O COOH

Λλ— (II) ^ cooc2H5 [Τ— ^ in racemic form or as an optical isomer, and for the preparation of pharmaceutically acceptable salts of this compound.

The compound of formula II has asymmetric carbon atoms. These carbon atoms are marked with an asterisk in formula II. Thus, the compound exists as optical isomers and diastereomers or racemates or mixtures thereof. All of these fall within the scope of the invention.

X-ray diffraction analysis of the single crystal of the N-3-bromobenzoyl derivative of octahydro-1H-indo-1-carboxylic acid used as a starting material in the present invention has shown that the junction of the cyclohexane ring with the cyano

B

In addition, octahydro-1H-indole-2-carboxylic acid is separated into portions via the α-phenylethylamine salt of its N-benzoyl derivative. Biologically active compounds are derived from either racemic or levorotatory forms of octahydro-1H-indole-2-carboxylic acid. Optical isomers and diastereomers due to the asterisked centers of asymmetry of formula II, as well as racemates and mixtures thereof, are within the scope of this invention. The S-configurations of the control panels are given priority.

The compound of formula II may exist in anhydrous form as well as solvated, including hydrates. Generally, hydrated forms and solvated forms with pharmaceutically acceptable solutions are equivalent for the purposes of this invention to anhydrous or non-solvated forms.

Compounds of formula II may be prepared by coupling an appropriately protected octahydro-1H-indole-2-carboxylate of the following formula & wherein R7 is a protected carboxylic acid group to a N-substituted amino acid of the following formula by peptide bond 3 76560 / ^ -CH -CHj-CH-COOCjDj

'-' NH-CH-COOH

C »3 and then the protecting group is removed and, if desired, the compound obtained is converted into a salt or the salt obtained is converted into the free compound.

The carboxyl group is preferably protected by forming an ester therefrom, e.g. by means of a benzyl group of a lower alkyl group or a trimethylsilyl group. The protected carboxylic acid compound is attached to an N-protected amino acid, e.g., L-alanine, the nitrogen of which is protected with a tert-butyloxycarbonyl group or a benzyloxycarbonyl group. The coupling can be performed using any of the conventional peptide coupling methods described, e.g., in "The Peptides. Analysis, Synthesis, Biology, Vol. 1. Major Methods of Peptide Bond Formation, Part A", ed. E.Gross. J. Meierhofer, Academic Press N.Y. (1979). Very useful is a process using a dehydrating reagent such as dicyclohexylcarbodiimide, either alone or in the presence of a reactive ester-forming reagent such as 1-hydroxybenztria-Sol in a suitable aprotic solvent such as dimethylformamide, acetonitrile, acetonitrile, tetrahydrofuran . The intermediate N-protected 2-aminoacyl-octahydro-1H-indole-2-carboxylic acid ester is obtained. The resulting product may be deprotected either in whole or in part, depending on the nature of the protecting groups, with the aid of anhydrous acids such as hydrochloric acid in acetic acid or trifluoroacetic acid in dichloromethane or hydrogen gas and catalyst to give the intermediate dipeptide in either free or protected form as an ester.

4,76560

The compound of formula II can then be prepared by reacting an intermediate dipeptide or an ester derivative thereof with an α-keto-4-substituted phenylbutyric acid or a lower alkyl ester thereof under dehydration and reduction conditions. Preferred dehydrating agents are molecular sieves in aprotic solvents and preferred reducing agents include e.g. sodium cyanoborohydride or hydrogen gas with catalyst.

Alternatively, a compound of formula II according to the invention may be prepared by reacting a dipeptide or ester derivative thereof with α-halo-4-substituted phenylbutyric acid or an ester thereof in the presence of a suitable basic reagent such as triethylamine or alkali metal carbonate or bicarbonate. -messa. Esteryl-protected products may be hydrolyzed under basic or acidic conditions to the free acids, or in the case of benzyl esters, catalytic hydrogenation may be preferred.

Another alternative way to prepare a compound of formula II obtainable according to the invention is as follows. Here, one of the two methods described above is applied, in which a 2- (4-phenylbutyric acid) group is attached to the protected dipeptide, but now the attachment is first to L-alanine, which is protected by esterification, to give N- [2- (4-phenylbutyric acid) substituted L- alanine.

The protecting group is then removed from the alanine portion of the product and the resulting monoacid is coupled to the octahydro-1H-indole-2-carboxylic acid protected by esterification, i.e., by itself or by deprotection of the amino group, by conventional methods. R7. When the ester groups and any amine protecting groups are selectively or completely removed, a compound of formula II is obtained.

The product is usually obtained as a mixture of diastereomers, which can be separated by customary fractional crystallization methods or by chromatography.

5,76560

The compound of the invention forms base salts with various inorganic and organic bases, and such salts are also within the scope of this invention. Suitable salts include e.g. ammonium salts, alkali metal salts such as sodium or potassium salts, alkaline earth metal salts such as calcium and magnesium salts, salts formed with organic bases such as dicyclohexylamine or benzatin, and salts formed with basic amino acids such as arginine, lysine and the like. Pharmaceutically acceptable salts are preferred, but other salts, such as the dicyclohexylamine salt, are also useful when, for example, it is desired to isolate, purify, or identify a product.

The salts are prepared in the usual manner by reacting the product in the free acid form with one or more equivalents of the required base to give the desired cation, in a solvent or medium in which the salt is insoluble, or in water to remove water by freeze-drying.

The compound of formula II may be formed into pharmaceutically acceptable acid addition salts by conventional reactions using equivalent amounts of organic or inorganic acids. Examples of pharmaceutically acceptable acid salts include salts formed with hydrochloric acid, sulfuric acid, acetic acid, fumaric acid, malic acid, maleic acid and citric acid.

When the enzyme renin acts on angiotensinogen, which is a pseudoglobulin in the blood plasma, angiotensin I, a decapeptide, is produced. Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II, which is octapeptide. The latter is an active antihypertensive agent and is thought to cause an increase in blood pressure in various mammalian species, e.g., rats and dogs. The 6,76560 compounds of this invention interfere with the renin-angiotensin I-angiotensin II sequence by inhibiting the angiotensin I-converting enzyme and reducing or eliminating the formation of hypertensive angiotensin II, thus being useful as a hypertensive agent. Thus, the condition of mammalian species suffering from hypertension can be alleviated by administering to them a mixture containing one or more compounds of formula II or a pharmaceutically acceptable salt thereof. For the reduction of blood pressure, it is usually sufficient to administer the active substance in a single dose or preferably in 2-4 single doses of about 0.1 to 100 mg per kilogram per day, preferably about 1 to 50 mg per kilogram per day. The compounds are preferably administered orally, but may also be administered parenterally, such as subcutaneously, intramuscularly, intravenously or intraperitoneally.

The following table shows the in vitro activity of a compound of formula II in an experiment to determine the inhibitory effect of an angiotensin converting enzyme, which is. a modification of the method by D.Cushman and H.Cheung, Biochemical Pharmacology, 20 ^, 1637-1648 (1971).

ACE assay in vitro: The inhibitory effect of angiotensin converting enzyme (ACE) is determined by examining the activity of guinea pig serum ACE in the presence and absence of test compound. Guinea pig serum ACE and test compound are incubated for 10 minutes, after which 1 H-hippuryl-glycylglycine is added as a labeled substrate. After incubation for 60 minutes at 37 ° C, the reaction is stopped by the addition of 0.1 N HCl. ACE cleaves the hippuryl-glycyl bond to form glycyl-glycine dipeptide and 3jj_jippururic acid. The 3-hippuric acid is then extracted with ethyl acetate and the inhibitory effect of ACE is calculated from the 3-h-hippuric acid formed from the sample.

7 76560

Table

COOH

CH30 I

'-' COOC2H5 / J

II IC50 configuration at (molar concentration) a) _b) _c) _ SS RS 2.4 x 10 ~ 7 SSS 7.2 x 10 “8 The IC50 is the molar concentration of a compound that inhibits 50% of the conversion of angiotensin I to angiotensin II.

The compound of the invention may be used for antihypertensive purposes in the form of tablets, capsules or elixirs for oral administration or as sterile solutions or suspensions for parenteral administration. About 10 to 500 mg of a compound of formula II, or a pharmaceutically acceptable salt thereof, is conventionally mixed with a pharmaceutically acceptable excipient or carrier which may contain excipients, binders, preservatives, stabilizers, flavors, etc. These preparations should contain the active ingredient in an amount such that the above-mentioned suitable dosage is achieved.

Suitable inert ingredients for use in tablets, capsules and the like include e.g. binders, such as gum tragacanth, acacia, corn starch or gelatin; , such as peppermint, gaulteria oil or cherry flavor. If the dosage unit form is a capsule, it may contain, in addition to materials of the above type, a liquid carrier such as an oil. Various other materials may be used as coatings or otherwise to modify the physical form of the dosage unit. The tablets may, for example, be coated with shellac or sugar or both. A syrup or elixir may contain the active ingredient, sucrose as a sweetening agent, methyl or propyl paraben as a preservative, a coloring agent and a flavoring such as cherry or orange flavor.

Sterile injectable formulations may be prepared by conventional pharmaceutical methods by dissolving or suspending the active ingredient in a water suitable for injection, vegetable oil such as sesame oil, coconut oil, peanut oil, preservatives, linseed oil, etc., or synthetic fat such as ethyl fat.

The invention is illustrated by the following Examples 1 and 3. Example 1: (2a, 3a6,7a3) -1- {2 - [(1-carbethoxy-3-phenylpropyl) -amino] -1-oxopropyl} -octahydro-1H-indole-2 -carboxylic acid hydrochloride.

To a solution of 5.57 g of the S, S-isomer of ethyl α - [(1-carboxyethyl) amino] -benzenebutanoate hydrochloride in 55 ml of dichloromethane is added 2.5 ml of triethylamine and the resulting solution is stirred at room temperature for 1 hour. . To this solution is first added 2.5 ml of triethylamine followed by 4.61 g of tert-butyl (dl) -octahydro-1H-indole-2-carboxylate hydrochloride, and the resulting mixture is stirred at room temperature overnight. The mixture is filtered and the filtrate is washed successively with 0.1 N acetic acid, water and saturated sodium chloride solution. After drying over magnesium sulphate and evaporation of the solvent under reduced pressure, 8.14 g of tert-butyl ester of the product are obtained in the form of a crude oil.

7.94 g of this tert-butyl ester are dissolved in 75 ml of dichloromethane, saturated with hydrogen chloride and left to stand at room temperature overnight. The solvent is evaporated off under reduced pressure and the residual foam is triturated with ether and collected. This material is dissolved in water, filtered and lyophilized. This gives 6.6 g of 23 product as a mixture of isomers, m.p. 112-150 ° C, [α] D = + 6.2 ° (1.05% in 1 N hydrochloric acid).

The ethyl α- (1-carboxyethylamino) benzene butanoate hydrochloride used as an intermediate in this process can be prepared as follows: To a solution of 2.0 g of tert-butyl L-alanine and 3.78 g of ethyl 2-bromo 4-Phenylbutanoate in 25 ml of dimethylformamide, 1.8 ml of triethylamine are added and the resulting solution is heated at 70 [deg.] C. for 18 hours, the solvent is removed under reduced pressure and the residue is taken up in water and extracted with ethyl ether, washed with water and dried over magnesium sulphate. is evaporated under reduced pressure to give the intermediate tert-butyl ester as an oil, and gas chromatographic analysis showed it to be pure enough for further use.

A solution of 143.7 g of this tert-butyl ester in 630 ml of trifluoroacetic acid is stirred at room temperature for 1 hour. The solvent is removed under reduced pressure, the residue is dissolved in ethyl ether and re-evaporated. This is repeated. A solution of hydrogen chloride in ethyl ether is then added dropwise to the ether solution until precipitation ceases. The product recovered by filtration is a mixture of diastereoisomers, m.p. 153-165 ° C [α] D 20 + 3.6 ° (c = 1, methanol).

To separate the preferred S, S isomer, a suspension of 10.0 g of the mixture and 200 ml of methylene chloride is stirred at room temperature for 5 minutes and filtered. The solid thus obtained, m.p. 202-204 ° C (dec.), [Α] D = -29.3 ° (c = 1, methanol) is a less preferred diastereoisomer having the R, S configuration (S represents the part derived from L-alanine). The preferred S, S-diastereoisomer can be recovered from solution from the filtrate by evaporation and trituration of the residue with ether. Sen sp. is 137-139 ° C, [α] D = + 31.3 ° (c = 1, methanol).

The second intermediate used in this preparation, tert-butyl (dE) -octahydro-1H-indole-2-carboxylate hydrochloride, is prepared as follows. To a solution of 20.0 g of (dE) -octahydro-1H-indole-2-carboxylic acid in 200 ml of dioxane in a pressure vessel are added 20 ml of concentrated sulfuric acid and 120 g of isobutylene and then stirred for 26 hours at 20 ° C. :in. The mixture is then poured into ice water containing 60 ml of 50% sodium hydroxide solution and the resulting mixture is extracted three times with ether. The ether is washed first with water and then with saturated sodium chloride solution and dried over magnesium sulfate. The ether solution is treated with a solution of hydrogen chloride in isopropanol and steam distilled to an oil which slowly crystallizes on standing. When the solid is collected and washed with ether, 11.33 g of ester hydrochloride are obtained, m.p. 112-116 ° C.

Example 2:

Resolution of octahydro-1H-indole-2-carboxylic acid

A solution of 20.0 g of racemic (2a, 3a | 3.7aG) -octahydro-1H-indole-2-carboxylic acid in 200 ml of water is cooled in an ice bath with 11 76560 while being added dropwise over 1.5 hours simultaneously but separately 14.4 ml of benzoyl chloride and 120 ml of 2N sodium hydroxide solution so that the pH remains between 6-8. The solution is stirred for a further 30 minutes and the pH is adjusted to 1.8 with 1 N hydrochloric acid. Racemic N-benzoyl-2- (2a, 3a6,7a3) -octahydro-1H-indole-2-carboxylic acid precipitates and is collected by filtration. Recrystallization from aqueous ethanol gives the pure product, m.p. 191-193 ° C.

87.75 g of this compound are added to a solution of 38.9 g of (1) -α-phenylethylamine in 700 ml of methanol to form a solution. This is diluted with 1250 ml of ethyl acetate and the separated salt is added as a seed crystal. The desired salt begins to precipitate from the mixture. After standing for 18 hours at 5 ° C and filtering off the salt, the product is obtained, m.p. 212-215 ° C (dec.) and [α] D 20 -49.4 ° (c = 1, methanol). Recrystallization from ethyl acetate-methanol (2: 1) gives a product having the same m.p. and rotation.

48.2 g of the levorotatory salt are suspended in a mixture of water (884 ml) and methanol (353 ml) and the pH is adjusted to 2 with dilute hydrochloric acid. After 15 minutes, the original solid dissolves and a new one separates. 430 ml of water are added and the precipitated (1) -N-benzoyl- (2a, 3a3,7aB) -octahydro-1H-indole-2-carboxylic acid is filtered off, m.p. 169-171 ° C, [α] D 20 = -51.4 ° (c = 1, methanol).

A suspension of (I) -benzoate in 200 ml of 6N hydrochloric acid is refluxed for 4 hours. The resulting solution is diluted with 100 ml of water and cooled. The precipitated benzoic acid is filtered off. The filtrate is extracted with chloroform, and the pH of the aqueous layer is adjusted to 6.5 with dilute sodium hydroxide solution. Evaporation of the filtrate to dryness gives a solid which is triturated and extracted with anhydrous ethanol. Concentration of the ethanol extract gives (1) - (2a, 3a6, 7a6) -octahydro-1H-indole-2-carboxylic acid, which can be purified by passing it through an acidic ion exchange resin using 2N ammonium hydroxide solution as eluent and a solid. the substance is separated and recrystallized from anhydrous ethanol. The m.p. 265-266 ° C (dec.), [α] D 3 - -48.5 ° (c = 1, methanol).

Example 3: (2a, 3a6,7a6) -1- (2 - [(1-Carbethoxy-3-phenylpropyl) -amino] -1-oxopropyl} -octahydro-1H-indole-2-carboxylic acid hydrochloride (S, S, S-isomer).

A solution of 1.23 g of the S, S-isomer of ethyl [(1-carboxyethyl) -amino] -benzene butanoate hydrochloride, 0.92 g of t-butyl N -) - octahydro-1H-indole-2-carboxylate, 0 .53 g of hydroxybenzotriazole monohydrate, and 0.54 ml of triethylamine in 15 ml of M, N-dimethylformamide are cooled in an ice bath and a solution of N, N'-dicyclohexylcarbodiimide in 2 ml is added dropwise. n, n-Dimethylformamide slide. The mixture is stirred for 1 hour at 0 ° C, the cooling is removed and stirring is continued at room temperature overnight.

The dicyclohexylurea is filtered off from the mixture and the N, N-dimethylformamide is distilled off under high vacuum. The residue is taken up in ethyl acetate, washed twice with saturated sodium bicarbonate solution and then with saturated sodium chloride solution. After drying over magnesium sulfate and removal of the solvent under reduced pressure, an oily residue is obtained. When this is mixed with ether, filtered and the ether is removed under reduced pressure, 1.9 g of crude tert-butyl ester product are obtained in the form of an oil.

A solution of 0.63 g of this tert-butyl ester in 6 ml of dichloromethane is saturated with hydrogen chloride and the mixture is stirred at room temperature overnight. The solvent is removed under reduced pressure, dichloromethane is added and the solvent is removed again. The residue is taken up in dichloromethane, treated with charcoal and filtered. When the solvent is removed under reduced pressure, a foam is obtained. Trituration with ether and recovery gives 0.35 g (58% yield) of product, talD = -29.7 ° (1.01%, 1: 1 methanol / 1 N hydrochloric acid).

The tert-butyl (&) - octahydro-1H-indole-2-carboxylate used as an intermediate in this process is prepared as follows. To a solution of 14.23 g of (E) -octahydro-1H-indole-2-carboxylic acid (prepared as described in Example 3 of FI patent application 81 0971) in 150 ml of dioxane are added 15 ml of concentrated sulfuric acid and 84 g of isobutylene and the resulting the mixture is kept at 20 ° C for 20 minutes with stirring. The mixture is then poured into ice water containing 45 ml of 50% sodium hydroxide solution and the resulting mixture is extracted three times with ether. The ether is washed first with water and then with saturated sodium chloride solution. After drying over magnesium sulphate and removal of the ether under reduced pressure, 14.4 g of the desired tert-butyl ester are obtained in the form of an oil, [α] D = -27.6 ° (1.1% in methanol).

Claims (1)

A process for the preparation of a pharmaceutically acceptable 1-12 - [(1-carboxyethoxy-3-phenylpropyl) amino] -1-oxopropyl] octahydro-1H-indole-2-carboxylic acid of the formula CH 2 O COOH ch 2 -. ch2- | h-nh-ch-cn-'x * N (II) W COCCjB * \ ^ zz7 in racemic form or as an optical isomer, and for the preparation of pharmaceutically acceptable salts of this compound, characterized in that the octahydroxy 1H-indole-2-carboxylate E wherein R7 is a protected carboxylic acid group, is coupled to the N-substituted amino acid L CH2-CH2-CH-COOC2H5 '-' NH-CH-COOH CH1 of the following formula by peptide bond and then the protecting group is removed, and, if desired, converting the obtained compound into a salt or the obtained salt into the free compound.