NL8104047A - METHOD FOR PREPARING A THERAPEUTIC PREPARATION, AND METHOD FOR PREPARING SUITABLE COMPOUNDS. - Google Patents

Description

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* A - - 1 -

A process for the preparation of a therapeutic preparation, as well as a process for the preparation of suitable compounds.

The invention relates to a method for preparing a therapeutic preparation with antihypertensive effect.

Such a method, in which a pro-line is brought into a form suitable for therapeutic application, can be considered to be known from the German "Offenlegungsschriften" 2,108,043 and 2,124,451. According to these "Offenlegungsschriften" one can use certain peptides with terminal proline groups to combat blood pressure increase. Namely, it has been found that these peptides are capable of inhibiting the enzyme, which converts angiotensin I, which is produced in the body, into angiotensin II, which substance has an antihypertensive effect.

According to the invention a compound of the formula I of the formula sheet is introduced, in which R represents a hydroxy or amino group or a lower alkoxy group, and each separately a hydrogen atom, an optionally substituted lower alkyl group with a phenyl group, or a phenyl group, R ,, a hydrogen atom or a group COR 2, where Rj. a phenyl, a lower alkylphenyl or phenyl-lower alkyl group and R 1 represents a hydrogen atom or a hydroxy group or lower alkyl group, n = 0, 1 or 2 and m = 1, or a base / salt thereof in a for therapeutic use suitable shape.

Namely, it has been found that these much simpler compounds, which are not peptides, are also suitable to effectively combat high blood pressure by the same mechanism. It is also important that they also exert this action when administered orally.

The lower alkyl groups represented by the above symbols include straight and branched chain hydrocarbon radicals from methyl to heptyl, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl and the like.

8104047 $; v - 2 -

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The lower alkoxy groups are of the same type with 1-7 carbon atoms, attached to the oxygen atom, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy and the like. The groups with 1 to 4 carbon atoms and in particular 5 with 1 or 2 carbon atoms are preferred. Phenylmethyl is the preferred phenyl lower alkyl group.

The lower alkanoyl groups are those with the acyl radicals of the lower (C 5 -C 7) fatty acids, for example, acetyl, propionyl, butyryl, isobutyryl and the like. The lower alkanoyl-10 groups with up to 4 carbon atoms, especially acetyl, are preferred.

The new compounds of the general formula 1 can be prepared in a manner known per se.

The compounds of formula 1 and the preferred subgroups can be prepared according to the invention using varying methods.

Generally, the compounds of the invention are prepared by acylating a compound of the formula 3 with an acid of the formula 4 or a chemical equivalent thereof.

Thus, the final product can be obtained not only by direct acylation with an Acid of the formula IV but also via intermediates such as (a) hal-haloalkanoic acids of the formula 5, wherein X is bromine, chlorine or iodine, or (b) a 25 8104047 • * \ - 3 - tosyloxyalkanoic acid, that is to say an acid of the formula 5 wherein X is tosyloxy (CH 3 - <©> - SCyj-), or (c) a substituted acrylic acid of the formula 6. The product of this acylation is then subjected to rearrangement or addition with the anion of a thiol or thioic acid of the formula 7.

The acylation can also be accomplished with a thiolactone of the formula 8, wherein η is 1 or 2, or a mercaptoalkanoic acid of the formula 9, wherein Y represents while, if a product of the formula 1, wherein R 2 represents hydrogen, is desirable Y may also represent a protecting group, such as (a) CH30— <§> —ch2, (b) Q1, (c) ch3conhch2, (d) R. R, t 1 14 ROC-CH- (CH) -S- or another sulfur protecting group. The deprotection can be accomplished using conventional methods, such as by treatment with hot trifluoroacetic acid, cold trifluoromethanesulfonic acid, mercuric acetate, sodium in liquid ammonia, zinc and hydrochloric acid or the like. In connection with these methods, reference is made to Methods of Organic Chemistry (Houben-Weyl), Vol. XV, part 20 I, p. 736 et seq. (1974).

When the acid of the formula IV is used as an acylating agent, the acylation can be accomplished in the presence of a coupling agent, such as dicyclohexylcarbo-diimide or the like, or the acid can be activated by forming its mixed anhydride, symmetrical anhydride, acid chloride. ride, acid ester or use of the Woodward reagent, K, N-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline, or the like. In connection with the acylation methods, reference is made to Methods of Organic Chemistry (Houben-Weyl), Vol. XV, Part II, p. 1 ff.

30 (1974).

Compounds of the formula 3 include azetidine-2-carboxylic acid and its lower alkyl esters. The acylation of such compounds is described in more detail below.

35 According to a preferred method of preparing 8104047 S? - 4 - compounds of the formula 1, especially of compounds in which 1 * 2 represents R 2 -CO-, an acid or ester of the formula 3 is coupled with a haloalkanoic acid of the formula 5, wherein X is halogen, preferably chlorine or bromine, represents. This can be accomplished by using any of the known procedures wherein the acid 4 is reacted with the acid 3 to react by forming a mixed anhydride, symmetrical anhydride, acid chloride or active ester or using Woodward reagent K, EEDQ (N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline) or the like. The product of this reaction is a compound of the formula 10. The product of the formula 10 is subjected to a displacement reaction with the anion of a thioic acid of the formula 7 to form a product of the formula 11 wherein R 2 represents R 1. CO, which product can then be converted by ammonolysis into the product of formula 12. When R2 is a protecting group, the compound of formula 12 can be obtained by removing the protecting group in the manner described above. When R is an ester group (ie, R represents lower alkoxy), the ester group can be removed, for example when R represents tert-butoxy or tert-amyloxy, by treating the ester of formula 11 or 12 with trifluoroacetic acid and anisole, whereby the corresponding free acid is obtained. When other alkoxy groups are present, the corresponding acid will be obtained by alkaline hydrolysis.

A variation of this procedure involves the use of an acrylic acid of the formula 6 as starting material. This acrylic acid is first converted to the acid halide form and then reacted with a compound of the formula 3 to form a compound of the formula 13 and this intermediate 30 is subjected to the addition reaction with the thiol or thioic acid 7 as described above.

A tosyloxyalkanoic acid of the formula 14 can also be used as the agent for the acylation of the acid of the formula 3, after which the acylation product is subjected to the displacement reaction, etc., as described above.

8104047 é * »% - 5 -

On the other hand, the acrylic acid of the formula 6 can first be reacted with the thioic acid of the formula 7 to form a product of the formula 15, which is converted into its acid halide, for example with. thionyl chloride, and then is coupled with the compound of formula 3, further following the procedure described above.

The acid or ester of the formula III can also be acylated with a "protected form of a ω-mercaptoalkanoic acid of the formula 16, wherein Rg is the" protecting "group.

Such "protecting" groups can be in the form described above.

After acylation, the protecting group can be removed from the product by any of the known methods described above.

Yet another acylating agent is a thiolactone, for example β-propiothiolactone, α-methyl-3-propiothiolactone or the like.

Further details regarding the preferred methods of preparing the compounds of the invention are set forth in the specific examples below.

In a particularly preferred modification of the process, the acid or ester of the formula 3 is acylated with a haloalkanoyl halide of the formula 17, wherein each X independently represents a halogen, preferably chlorine or bromine, R represents hydrogen, lower alkyl or phenyl-lower alkyl and n is 0, 1 or 2. This reaction is effected in an alkaline medium, for example, a dilute alkali metal hydroxide solution, alkali metal hydrogen carbonate or alkali metal carbonate solution, at a reduced temperature, for example about 0-15 ° C. The reaction product is subjected to a placement reaction with the anion of the thiol or thioic acid of the formula 7, also in an alkaline medium, preferably an alkali metal carbonate solution, and then worked up in the usual manner. The product of this reaction, wherein R 1 -CO in the formula 1, is converted into the product, wherein R 2 8104047

0 V.

- 6 - represents hydrogen, by ammonolysis, for example with alcoholic ammonia or concentrated ammonium hydroxide solution, or by alkaline hydrolysis, for example with aqueous metal hydroxide. When an acid of the formula III is used as starting material, the final product obtained as the free carboxylic acid can then be converted into its ester, for example, by esterification with a diazoalkane, such as diazomethane, an 1-alkyl-3-p-to- lyl triazene, such as 1-butyl-3-p-tolyl triazene or the like.

The treatment of an ester, preferably the methyl ester, with an alcoholic ammonia solution converts the free acid into the amide, ie a product in which R represents N 11.

In another variation of the process, an ester, preferably the t-butyl ester of the formula 3, in an anhydrous medium, such as dichloromethane, tetrahydrofuran, dioxane or the like, is treated with a thioalkanoic acid of the formula 18 in the presence of dicyclohexylcarbodiimide , N, N'-carbonyl bisimidazole, ethoxyacetylene, diphenylphosphoryl azide or analogous coupling agents at a temperature of about 0-10 ° C. The ester group (R) can then be removed, for example by treatment with trifluoroacetic acid and anisole at room temperature.

When an ester of the formula 3 (eg R is lower alkoxy, especially t-butoxy) is acylated with a thiolactone, eg β-propiothiolactone, α-methyl-β-propio-thiolactone or the like, the reaction can be carried out in a anhydrous solvent, such as tetrahydrofuran, dioxane, methylene chloride or the like, at about 0 ° C to about room temperature. The ester group can then be removed with anisole and trifluoroacetic acid as described above.

Products of the formula 1 have one or more asymmetric carbon atoms. When R ^, R ^ or R ^ have a meaning other than hydrogen, the carbon atom to which this substituent is attached is asymmetric. These carbon atoms are indicated by an asterisk in formula 1. The compounds therefore exist in stereoisomeric forms or in racemic mixtures 8104047-7 thereof. All these forms and mixtures are within the scope of the invention. In the syntheses described above, the starting materials may be the racemate or one of the enantiomers. When the racemic starting material is used in the synthesis, the stereoisomers obtained in the product can be separated using conventional chromatographic or fractional crystallization methods. Generally, with respect to the carbon atom of the amino acid, the L isomer is the preferred isomeric form. Also preferred is the D isomer with respect to the α-carbon atom in the acyl side chain (ie, the carbon atom that bears it).

The compounds of the invention form basic salts with different inorganic and organic bases, which salts are also within the scope of the invention.

Such salts include ammonium salts, alkali metal salts such as sodium and potassium salts (which are preferred), alkaline earth metal salts such as the calcium and magnesium salts, salts with organic bases, eg the dicyclohexylamine salt, benzathine, N-methyl-D-glucamine - hydrabaminel salts, salts with amino acids, such as arginine, lysine and the like. The non-toxic, physiologically acceptable salts are preferred, although other salts are also useful, for example, in the isolation or purification of the product, as illustrated in the examples for the case of the dicyclohexylamine salt.

The salts are conventionally formed by reacting the free acid form of the product with one or more equivalents of the appropriate base, which provides the desired cation, in a solvent or medium in which the salt is insoluble, or in water and removal of the water by freeze drying.

By neutralizing the salt with an insoluble acid, such as a cation exchange resin in the hydrogen form (eg polystyrene sulfonic acid resin such as Dowex 50) or with an aqueous acid and extraction with an organic solvent, eg ethyl acetate, dichloromethane or the like, the free acid form and, if desired, another salt are formed.

8104047 * <r v - 8 -

Further experimental details are indicated in the examples, which describe preferred embodiments and also serve as a model for the preparation of other members of the group.

The compounds of the invention inhibit the conversion of the decapeptide angiotensin I to angiotensin II and are therefore useful for lowering angiotensin-related hypertension. Angiotensin I is formed by the action of the enzyme renin on angiotensinogen, a pseudoglobulin in blood plasma. Angiotensin I is converted into angiotensin II by angiotensin converting enzyme (ACE). The latter is an active blood pressure raising agent, which is considered to be the cause of different forms of hypertension in different mammalian species, for example rats and dogs. The compounds of the invention block the conversion of angiotensin (renin) angiotensin I to angiotensin IX by inhibiting the angiotensin converting enzyme and reducing or eliminating the formation of blood pressure-increasing angiotensin II. By administration of a composition containing one or more compounds of the formula I and / or physiologically acceptable salts thereof, angiotensin-induced hypertension in suffering mammals can be reduced. A single dose or preferably 2-4 daily divided doses based on about 0.1-100 mg per kg per day and preferably about 1-50 mg per kg per day is suitable for lowering blood pressure, as shown by the animal experiments described by SL Engel, T.R. Schaeffer, M.H. Waugh, and B. Rubin, Proc. Soc. Exp. Biol. Med. 143, 483 (1973). The substance is preferably administered orally, but parenteral administration, such as subcutaneous, intramuscular, intravenous or intraperitoneal administration, can also be used.

The compounds of the invention can be used to lower blood pressure in the form of preparations, such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral administration. About 10-500 mg of a compound or mixture of 8104047-9 compounds of formula 1 or physiologically acceptable salts thereof are mixed with physiologically acceptable carriers, binders, preservatives, stabilizers, flavors, etc. to form a unit dosage form as 5 required in pharmaceutical practice. The amount of active substance in these preparations is such that an appropriate dose is obtained within the above range.

Examples of additives that can be included in tablets, capsules and the like are the following: a binder such as gum tragacanth, acacia gum, corn starch or gelatin, a carrier such as dicalcium phosphate, a disintegrant such as corn starch, potato starch, alginic acid and the like, a lubricant, such as magnesium stearate, a sweetener, such as sucrose, lactose or saccharin, and a flavoring agent such as peppermint, wintergreen or cherry oil. When the unit dosage form is a capsule, it may additionally contain, in addition to the materials of the above type, a liquid carrier, such as a fatty oil. Various other materials may be present as coatings or to further modify the unit dose physical form. For example, tablets can be coated with shellac, sugar or both. A syrup or elixir may contain the active compound, sucrose as a sweetener, methyl and propyl parabens as preservatives, a colorant and a flavoring agent such as cherry or orange flavor.

Sterile preparations for injection can be prepared according to conventional pharmaceutical procedures by dissolving or suspending the active substance in a carrier, such as water for injection, a naturally occurring vegetable oil, such as sesame oil, coconut oil, peanut oil, cottonseed oil, etc., 30 or a synthetic fat, such as ethyl oleate or the like. If necessary, buffers, preservatives, anti-oxidants and the like can be included.

The invention is further illustrated but not limited by the following examples.

35 8104047.> "V - 10 -

Example_I

1- (2-Benzoylthioacetyl) -L-azetidine-2-carboxylic acid L-azetidine-2-carboxylic acid (5.05 g) is dissolved in N. sodium hydroxide (50 ml) and the solution is cooled in an ice-water bath. Sodium hydroxide 2N (26 ml) and chloroacetyl chloride (5.65 g) are added and the mixture is added for 3 hours. stirred vigorously at room temperature. A suspension of thiobenzoic acid (7.5 g) and potassium carbonate (4.8 g) in water (50 ml) is added. After stirring at room temperature for 18 hours, the reaction mixture is acidified and extracted with ethyl acetate. The ethyl acetate layer is washed with water, dried over magnesium sulfate and evaporated to dryness in vacuo. The residue (14.6 g) is dissolved in ethyl acetate (150 ml) and dicyclohexylamine (11 ml) is added. The crystals are filtered and recrystallized from ethyl acetate. In order to convert the salt to the acid, the crystals are dissolved in a mixture of 5% aqueous potassium hydrogen sulfate (100 ml) and ethyl acetate (300 ml). The organic phase is washed once with water, dried over magnesium sulfate and evaporated to dryness in vacuo.

Example II

1- (2-Mercaptoacetyl) -L-azetidine-2-carboxylic acid.

1- (2-Benzoylthioacetyl) -L-azetidine-2-carboxylic acid (3.29 g) is dissolved in a mixture of water (10.5 ml) and concentrated ammonia (6.4 ml). After 1 hour, the reaction mixture is diluted with water and filtered. The filtrate is extracted with ethyl acetate and then acidified with concentrated hydrochloric acid, saturated with sodium chloride and extracted 2 times with ethyl acetate. The ethyl acetate extracts are washed with saturated sodium chloride and evaporated to dryness;

The product, 1- (2-mercaptoacetyl-L-azetidin-2-carboric acid) is crystallized from ethyl acetate.

35 8104047 - 11 -

Example ^ III

a) Tert-butyl ester of L-azetidine-2-carboxylic acid.

L-Azetidine-2-carboxylic acid (202 g) is dissolved in a mixture of water (1 L) and 5 N sodium hydroxide (400 ml).

The solution is cooled in an ice bath, and with vigorous stirring, 5N sodium hydroxide (460ml) and benzyloxycarbonyl chloride (340ml) are added in five equal portions over a 30 minute period. After stirring for 1 hour at room temperature, the mixture becomes 10 Extracted 2 times with ether and acidified with concentrated hydrochloric acid. The precipitate is filtered off and dried.

The benzyloxycarbonyl-L-azetidine-2-carboxylic acid thus obtained is dissolved in a mixture of dichloromethane (300 ml), liquid isobutene (800 ml) and concentrated sulfuric acid (7.2 ml). The solution is shaken in a pressure bottle for 72 hours. The pressure is released and the isobutene is allowed to evaporate, then the solution is washed with 5% sodium carbonate, water, dried over magnesium sulfate and evaporated to dryness in vacuo to give benzyloxycarbonyl-L-azetidine-2-carboxylic acid t-butyl ester.

Benzyloxycarbonyl-L-azetidine-2-carboxylic acid tert.-butyl ester (109 g) is dissolved in absolute ethanol (1.2 L) and hydrogenated at normal pressure with 10% Pd on carbon (10 g) until only one trace remains carbon dioxide is observed in the effluent hydrogen gas (24 hours). The catalyst is filtered off and the filtrate concentrated in vacuo at 30 mm Hg. The residue is distilled in vacuo to give the t-butyl ester of azetidine-2-carboxylic acid.

b) 1- (3-Acetylthiopropanoyl) -L-azetidin-2-carboxylic acid tert-butyl-30 ester.

L-Azetidine-2-carboxylic acid tert-butyl ester (4.71 g) is dissolved in dichloromethane (40 ml) and the solution is cooled in an ice water bath. A solution of dicyclohexylcarbo-35 diimide (6.18 g) in dichloromethane (20 ml) is added, 8104047

* V

- 12 - immediately followed by 3-acetylthiopropionic acid (4.45 g). After 15 min, stirring in the ice-water bath and 16 hours at room temperature, the precipitate is filtered off and the filtrate evaporated in vacuo. The residue is dissolved in ethyl acetate and washed until neutral reaction. The organic layer is dried over magnesium sulfate and evaporated to dryness in vacuo to give the title compound.

Example_IV

1- (3-Acetylthiopropanoyl) -L-azetidine-2-carboxylic acid.

10 '1- (3-Acetylthiopropanoyl) -L-azetidine-2-carboxylic acid tert.-butyl ester (4.5 g) is dissolved in a mixture of anisole (34 ml) and trifluoroacetic acid (68 ml) and the mixture is Kept at room temperature for 1 hour. The solvents are removed in vacuo and the residue is precipitated several times from ether-hexane. The residue (3.5 g) is dissolved in acetonitrile (25 ml) and dicyclohexylamine (2.8 ml) is added. The crystalline salt is filtered off and recrystallized from isopropanol; yield 3.8 g; mp, 176-177 ° C. The salt is again converted into 1- (3-acetylthiopropanoyl) -azetidine-2-carboxylic acid as in Example I.

Example V

1- (3-Mercaptopropanoyl) -L-azetidine-2-carboxylic acid.

1- (3-Acetylthiopropanoyl) -L-azetidine-2-carboxylic acid (0.75 g) is dissolved in 5.5 N, methanolic ammonia (5 ml) and the solution is kept in an argon atmosphere at room temperature. After 2 hours, the solvent is removed in vacuo, the residue is dissolved in water and the solution is placed in an ion exchange exchanger column in the H + cycle / Dowex 50 (analytical grade) and eluted with water. The fractions giving a positive thiol reaction are collected and evaporated to dryness; this product is crystallized from ethyl acetate-hexane to give the title compound.

35 8104047 <- 13 -

Example_VI

1- (3-Acetylthio-2-methylpropanoyl) -L-azetidin-2-carboxylic acid tert-butyl ester.

5 L-Azetidine-2-carboxylic acid tert-butyl ester (4.8 g) is dissolved in dichloromethane (40 ml) and the solution is stirred and cooled in an ice bath. Dicyclohexylcarbodiimide (6.2 g) dissolved in dichloromethane (15 ml) is added followed immediately by a solution of 3-acetylthio-2-methylpropanoic acid 10 (4.9 g) in dichloromethane (5 ml). After stirring in the ice bath for 15 min and at room temperature for 16 hours, the precipitate is filtered off and the filtrate is evaporated in vacuo. The residue is dissolved in ethyl acetate and washed until neutral reaction. The organic phase is dried over magnesium sulfate and evaporated to dryness in vacuo.

The residue, 1- (3-acetylthio-2-methylpropanoyl) -L-azetidine-2-carboxylic acid tert-butyl ester, is purified by column chromatography (silica gel chloroform).

Example_VII

1- (3-Acetylthio-2-methylpropanoyl) -L-azetidine-2-carboxylic acid.

20

The 1- (3-acetylthio-2-methylpropanoyl) -L-azetidin-2-carboxylic acid tert-butyl ester of Example VI (7.3 g) is dissolved in a mixture of anisole (55 ml) and trifluoroacetic acid (110 ml).

After storage for 1 hour at room temperature, the solvent is removed in vacuo and the residue precipitated several times from ether hexane. The residue (6.8 g) is dissolved in acetonitrile (40 ml) and dicyclohexylamine (4.5 ml) is added. The crystalline salt is boiled with fresh acetonitrile (100 ml), cooled to room temperature and filtered. This material is crystallized from isopropanol. The crystalline dicyclohexylamine salt is suspended in a mixture of 5% aqueous potassium hydrogen sulfate and ethyl acetate. The organic phase is washed with water and evaporated to dryness. The residue is crystallized from ethyl acetate-hexane to give 1- (3-acetylthio-2-D-methylpropanoyl-L-35 azetidine-2-carboxylic acid).

8104047-14 - Y22 Keeld_viii 1- (3-Mercapto-2-D-methylpropanoyl) -L-azetidine-2-carbonic acid.

The thioester (0.80 g) is dissolved in 5.5 N.

Methanolic ammonia and the solution is kept at room temperature for 2 hours. The solvent is removed in vacuo and the residue dissolved in water, applied to an ion exchanger column in the H + cycle (Dowex 50, analytical grade) and eluted with water. The fractions giving a positive thiol reaction are combined and frozen dry. The residue is crystallized from ethyl acetate-hexane.

Example_IX

1- (4-Benzoylthiobutanoyl) -L-azetidine-2-carboxylic acid.

To a solution of L-azetidine-2-carboxylic acid (2.53 g) in normal sodium hydroxide (25 ml), cooled in an ice bath, 2 N, sodium hydroxide (12.5 ml) and 4-chlorobutyryl chloride (3.5 g) added. The reaction mixture is stirred at room temperature for 3.5 hours and a suspension of thio-20 benzoic acid (3.75 g) and potassium carbonate (2.4 g) in water (25 ml)

will be added. After stirring overnight at room temperature, the reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and evaporated to dryness in vacuo. The residue is chromatographed on a column of silica gel with benzene acetic acid (7: 1). The fractions containing the desired material are combined and evaporated to dryness. A small sample of this material is dissolved in ethyl acetate and dicyclohexylamine is added to a pH of 8-10 (determined with a wet pH paper-30). The dicyclohexylamine salt crystallizes immediately. Example X.

1- (4-Mercaptobutanoyl) -L-azetidine-2-carboxylic acid.

1- (4-Benzylthiobutanoyl) -L-azetidine-2-carboxylic acid (1.01 g) is dissolved in a mixture of water (4 ml) and 8104047-15 concentrated ammonia (2.7 ml). After stirring at room temperature for 1 hour, the mixture is diluted with water, filtered, extracted with ethyl acetate and the aqueous phase concentrated in vacuo. The resulting ammonium salt of 1- (4-mercaptobutanoyl) -L-proline 5 is purified by ion exchange chromatography on a column of diethylaninoethyl-Sephadex (cross-linked dextran) with a gradient of ammonium hydrogen carbonate. The ammonium salt is dissolved in water (2 ml) and applied to a column of Dowex 50 sulfonic acid resin (analytical grade) in the hydrogen form and the free acid is eluted with water. The. fractions containing the desired material (positive reaction with sulfhydryl reagent and carboxyl reagent) are combined and lyophilized to yield 1- (4-mercaptobutanoyl) -L-azetidine-2-carboxylic acid. The dicyclohexylammonium salt is prepared according to the procedure of Example IX.

8104047

Claims (4)

A process for the preparation of a therapeutic preparation having an antihypertensive effect, characterized in that a compound of the formula 1, in which R is a hydroxy or amino-5 group or a lower alkoxy group, R 1 and R 4 are each a hydrogen atom, an optionally substituted lower alkyl group or a phenyl group, R 1 is a hydrogen atom or a group COR 2, wherein R 8 represents a phenyl, a lower alkyl phenyl or phenyl lower alkyl group, and R 1 represents a hydrogen atom or a hydroxy or lower alkyl group and n = 0, 1 or 2 and m = 1, or a base salt thereof, in a form suitable for therapeutic use. 2. Process for preparing a compound suitable for use in the process according to claim 1, characterized in that a compound of the formula 1, wherein R, R 1, R 2, R 1, R 1, m and n have the same meaning as in claim 1, prepared in a manner customary for such compounds. 20 8104047. * v '·. Rtg.nr.i 115,777 R4 R) Ri, Rl, 1, 1 J. IV Rj-S— (ChJ - CH — COOH X - (CH) ,, - CH — COX 16 17 Ri Μ MI η II Ri-S- (CH8) W — CH- COOH 18 Ry-MC-Xg Rj — MCS -Me ^ g M Rii Rj — N = C = Μ Η I 'I 0 21 Ri-NH-CS- (CH) W — Ch-COOH i_s_R 22 24 lower alkyl— CO - NHCH ^ OH 0 po μ ά Ré - s - s - r6 R <; S - xo 25 26 Rt — S —S0JH R & —S - SCN 27 28 f »(HO —— CH, R, Ri ^ I * IS I1 I R-OC — HC-N-CO-CH- (CH \ —S (oL * *« Λ Λ, p 29 ER Squibb & Sons »Inc. of Princeton, New Jersey · ι II mu« r «y · Ver, St .V, America 8104047 * 'Rj .1. ReK. No .: 113.777" 4 R, h4c- (ch ) ^ R, —s—- (C Η) -CH - CO —N-— CH — COR * '*' n ^. · * ·? »H * c - (Crt)». 3 HN - CH— COR * 1 Rt, I 4 Rj— S— (chJ „- CH — COOH HJ *}! R4 Ri X— (CH ^ -CH — COOH 5 CH = -C —COOH g (ίΗ) - ίΗ 8 Ri— SH s_c 7 S0 RJ, R, Ί * ys- (ch) -ch-cor g R4 Rf h2c - (ch] w 10 x— (CH) eT— CH-CO— N-- CH-COR Rj R4 Rl H * C - (CH) ,. R ^ —S— (ch) „- CH - CO —N— CH — COR 1» 11 Rk R, HS— (ch) - CH —CO— N — CH —COR R 12 1 fty R ·) HjC - (CH) W CH ~ C— CO— N-CH — COR 13 r4 R,. I-Λ I I CH ^ / ySO ^ O-fCH ^ -CH-COOH R u r i1 is Rg — S —CH - CH - COOH E.R. Squibb 4 Sons, Inc. 8104047 ta Princeton, New Jersey Var. St. America