DK148902B - METHOD OF ANALOGUE FOR THE PREPARATION OF TRH-ANALOGUE DERIVATIVES OF N-SUBSTITUTED HISTIDYL PROLINAMIDE OR PHARMACEUTICALLY USED ACID ADDITION SALTS - Google Patents

Description

148902

The present invention relates to an analogous method for preparing novel TRH analog derivatives of histidyl-prolinamide or pharmaceutically useful acid addition salts thereof, one or both of the amino acids of this dipeptidamide being optically active or racemic, but preferably present in the L configuration. The derivatives of N-substituted histidylprolinamide prepared by the process according to the invention are compounds of the general formula I or salts of these compounds with pharmaceutically usable acids, in which formula R and R are the same or different and (with the proviso, 1 2 that not both symbols R and R can simultaneously mean hydrogen) represents hydrogen, alkyl groups of up to 6 carbon atoms or 2 cyclohexyl or benzyl group, or together with the nitrogen atom to which they are attached form a piperidine ring, and Z represents one of the groups a) -NH-CO-CH- (which can also be written in the tautomeric form • 4 c R R6 -N = C - CH -) or b). - C - S - CH0 ~ I4 ic 2 OH R r5 3 4 wherein R together with R represents a further bond between the carbon atoms to which they are attached or, when Z is the group b), R ~ * represents a hydrogen atom, while R 3 and R 2 are the same or different and represent hydrogen or alkyl groups having 1-3 carbon atoms.

As to the carboxylic acid of formula II attached to the dipeptide

I t '1 3

• 1 RJ

In I / TT

.C C XI

COOH I

H

preferably it is the orotic acid, thiomorpholine- (5) -one- (3) -carboxylic acid or thiomorpholine- (6) -methyl- (5) -one- (3) -carboxylic acid.

When Z is the group b) and / or when R and R are different from each other, the acid residues of the acids of formula II may also be in racemic or optically active form (with up to two centers of asymmetry, as indicated by the inserts in the following formula for thiomorpholine ((6) -methyl- (5) -one- (3) -carboxylic acid), preferably in L-besides, in the compounds of the parent I: "3 ^ S-CH2 H ^ f | 2" * C /

COOH

N

H

2

Preferably, if R is hydrogen, R represents a straight chain alkyl group of 1-6 carbon atoms, especially of 1-4 carbon atoms.

2

Due to the basicity of the histidine residue, the compounds of formula I are capable of forming salts with acids. Therefore, in the process according to the invention, the preparation of salts of these compounds with pharmaceutically (in salt form) useful inorganic or organic acids, such as e.g. hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, propionic acid, benzoic acid, salicylic acid, phenylacetic acid or benzenesulfonic acid.

The compounds obtained by the process according to the invention exhibit biological properties which are very similar to those of pyroglutamyl-histidyl-prolinamide, usually referred to as "Thyrotropin-Releasing-Hormone" or "TRH" in terms of efficacy, but lasting considerably longer than the known product. In addition, it is of therapeutic importance that the ratio of the central stimulating effects to the endocrinological effects of the compounds obtained by the process according to the invention in comparison with the known product (TRH) is offset in favor of the pharmacologically valuable properties. The compounds of this invention are active in parenteral and oral administration, where the onset of action occurs rapidly, e.g. by parenteral administration after approx. 10 minutes.

The prevailing symptoms correspond to central stimulation in pharmacological tests. If test animals are given equal doses of TRH and a product obtained by the process of the invention, it appears that the latter acts centrally stimulating several times longer than TRH.

The toxicity of the compounds is very low, so that the compounds e.g. can be used as psychostimulants or as anti-depressants. The products can be used for both humans and animals. Suitable pharmaceutically useful formulations are tablets, dragons, granules, capsules, drops, juices or syrups, spray preparations for intranasal administration or for administration of the substances via the bronchi, as well as aqueous, sterile solutions for parenteral administration.

From Swedish Patent Specification No. 400,074 and from the specification to Danish Patent Application No. 994/75, TRH analogues are known in which the ring in the pyroglutamyl residue in TRH (pyroglutamyl-histidyl-proline-amide) is replaced by various, mainly 5-membered heterocyclic rings. , and the terminal NH 2 group is unsubstituted. In the disclosure of Danish Patent Application No. 4637/75 published after the priority date of the present invention, TRH analogs are described in which the ring in the pyroglutamyl residue is substituted with various 6-membered heterocyclic rings and wherein the terminal NH 2 group is also unsubstituted. These last TRH analogs are distinguished by the above-mentioned known TRH analogs i.a. know that they are more resistant to enzymatic degradation caused by enzymes found in the body. It has now surprisingly been found that the compounds prepared by the process of the present invention differ only from the compounds disclosed in the specification for Danish Patent Application No. 4637/75 in that they are alkyl, cyclohexyl or benzyl substituted therein. terminal Nik, group,, is. even more resistant to said enzymatic degradation. These conditions will be evident from the experimental data set out in the table below.

Table

Degradation of TRH and its analogues of the formula A-His-Pro-B, caused by various enzymes present in the body (% of TRH cleavage).

Compound A B Pyroglutamate- Desamidase _aminopeptidase_ TRH t-i -NH- (100) (100)

H

Example 3 c

Swedish Manufacturers / V

writing 400,074 -NH, 92.5 96.1

H

Example 1

Danish ans. V

No. 994/75 Λ, η 0 li -NH0 201.7 94.6 Γ o

Ϊ »A

0 * SAo- _1®2 0 1 ° 4'4

N

T I -NH 2 0 66.8 0

H

._ \ _____ 5 148902 _Table (continued) _

Compound A B Pyroglutamate Desamidase _aminopeptidase_

Current Description _

Examples / 2 and 9 µ / -NHCH 3 0 8.2

r I

Example 4V S -mc.Ua \ 4 9 0 0 H -

Example 3 / -NH - ^ H - O 0

Example 6 20 O -NHCH, O 7.9

Example ΐ I

1, 8 and 10

H

Neither for the compounds of Example 5 (A = orotyl, B = -NH “CgH13)) and Example 7 (A = orotyl, B = -NHC ^CgH₂) any degradation caused by pyroglutamate aminopeptidase or desamidase was observed.

The process according to the invention is characterized by the characterizing part of the claim.

Thus, the compounds of general formula I can be prepared according to process a) of the invention by reacting an N-substituted histidyl proline amide of formula III (see claim), wherein R dg R has the above meanings and wherein the two amino acids are present in the desired optical configuration, with an acid 3 of formula II wherein R and Z have the above meanings, in the presence of a water-binding agent, especially a carbodiimide (preferably; dicyclohexylcarbodiimide), or with a functional derivative of. an acid of formula II, e.g. an acid halide, an anhydride or a mixed anhydride, an azide or an activated ester.

6 148902

For the preparation of the compounds of formula I, it is also possible to proceed by the process b) according to the invention, by reacting a compound of formula IV (see claim) wherein R 1 and Z have the above meanings, in the presence of a water-binding agent, in particular a carbodiimide, preferably dicyclohexylcarbodiimide, or a functional derivative of a compound of formula IV, e.g. an acid halide, a mixed anhydride or an activated ester, with a compound of formula V (see claim), 12 wherein R and R have the above meanings.

The compounds of formula I can also be obtained according to process c) of the invention by reacting a compound 3 of formula VI (see claim) wherein R and Z have the above meanings and W represents a hydroxy or acyloxy group, nitrophenoxy, tri or pentachlorophenoxy, pentafluorophenoxy, pyridyloxy, phenylmercapto, p-nitrophenylmercapto or cyanoomethyloxy group or an N-hydroxysuccinimide group having an amine of formula VII (see R), wherein R the above meanings.

In particular, as mixed anhydrides of acids of formulas II and IV, those derived from mono esters of carbonic acid with aliphatic alcohols containing 1-4 carbon atoms, or e.g. of trimethylacetic acid (pivalic acid). Suitable activated esters of said acids are derived e.g. of p-nitrophenol, tri- or pentachlorophenol,, pentafluorophenol, U-hydroxysuccinimide, 2- or 4-hydroxypyridine, thiophenyl, p-nitrothiophenol, glycolic acid nitrile, l-hydroxybenzotriazole, and other in the peptide chemistry of

The compounds obtained by the process according to the invention are relatively stable and can therefore be purified by e.g. precipitation and recrystallization, but also by column chromatography, countercurrent distribution, etc.

The process according to the invention is further elucidated by means of the following examples, in which all temperature indications are uncorrected and whose execution did not emphasize the attainment of optimal yields.

7 148902

Example 1 a) To a solution of 12/7 g of methylamine in 350 ml of absolute tetrahydrofuran is added 71 g of benzyloxycarbonyl-L-proline-N-hydroxy-succinimide ester with stirring at 0 ° C. The mixture is stirred for 15 minutes at 0 ° C and for 2 hours at room temperature, the solvent is evaporated in vacuo, the residue is taken up in vinegar ester and the vinegar ester solution is washed successively with 5% potassium hydrogen sulfate solution, saturated sodium hydrogen carbonate solution and water. Evaporation of the acetic acid solution dried over sodium sulfate gives 46 g (85%) of benzyloxycarbonyl-L-proline methylamide in the form of a colorless, viscous oil which crystallizes fully at 3-5 ° C but melts again at room temperature. .

b) 102.3 g of benzyloxycarbonyl-L-proline methylamide is hydrogenated in methanolic solution in the presence of freshly prepared palladium and 22.3 ml of glacial acetic acid. After filtration of the catalyst, 100 ml of ca. 4 N hydrochloric acid, evaporate the solution in vacuo and repeat the evaporation three times after the addition of some ml of ethanol (absolute). The crystalline residue is recrystallized from methanol-ether (60: 200). After drying in vacuo over phosphorus pentoxide, 49.7 g (77%) of L-proline-methylamide hydrochloride is obtained, m.p. 165 ° C. [α] D = -55.3 ° (c = 1, methanol).

c) In a cooled suspension of 60.8 g of benzyl-oxycarbonyl-L-histidine hydrazide in 400 ml of dimethylformamide, 228 ml of a 4.38 M solution of hydrogen chloride in absolute tetrahydrofuran is added. At -15 to -20 ° C, 24.0 ml of tert-butyl nitrite is added dropwise in such a way that the temperature does not exceed -15 ° C. Upon completion of drip, stir for another 30 minutes at -15 ° C. The reaction solution is then cooled to -45 ° C and drops of 139.0 ml of triethylamine in such a way that the temperature does not exceed -30 ° C. Then 32.9 g of L-proline methylamide hydrochloride and then 27.8 ml of triethylamine (absolute) are added. After 15 minutes of reaction time, another 22.0 ml of N-methylmorpholine is added, the temperature is allowed to rise within 24 hours with stirring to room temperature and then the precipitate is extracted. The residue obtained by evaporation of the filtrate is dissolved in 300 ml of water with the addition of some hydrochloric acid. The solution is added to concentrated ammonia solution to pH 9, thereby separating an oil. The aqueous layer is decanted off and the oil is dissolved in tetrahydrofuran. After the addition of an equal amount of vinegar ester, several times with water. The organic phase dried over sodium sulfate is evaporated in vacuo. After drying in vacuo over phosphorus pentoxide, 46.5 g (58%) of benzyloxycarbonyl-L-histidyl-L-proline methylamide is obtained in the form of a foamy solidified mass, [α] 4 = -40 D) 30 g of benzyloxycarbonyl-L-histidyl-L-proline methylamide are dissolved in 100 ml of glacial acetic acid and after addition of 100 ml of a 40% solution of hydrogen bromide in glacial acetic acid is stirred. for 1 hour at room temperature. The precipitate which is precipitated by the addition of 500-600 ml of dry ether is extracted, washed with dry ether and dried over phosphorus pentoxide / potassium hydroxide in vacuo. Thus, hydrobromide of L-histidyl-L-proline-methylamide and 12.8 g of thiomorpholine-βίο, L) -phyllethyl-5-one-3- (L) -carboxylic acid and 10.5 g of 1-hydroxybenzotriazole are dissolved in 150 ml of dimethylformamide and, while cooling in an ice bath, is added to the equivalent salt bromide equivalent of triethylamine and then 15.0 g of Ν, Ν'-dicyclohexylcarbodiimide dissolved in slightly dimethylformamide. The mixture is stirred for 10 minutes in the ice bath and then for 12 hours at room temperature. The precipitated precipitate is aspirated, the filtrate is evaporated in vacuo and the residue thus obtained is dissolved in 150 ml of water.

After, leave in refrigerator at cubicle. The precipitate is suctioned off at 3 ° C. The filtrate is added with an equal volume of methanol and stirred with a cation exchange resin, namely the product known by the trade name "Dowex ^ BO WX 4 (acid form)". The resin adsorbate is aspirated, washed with methanol and water, suspended in methanol-water (1: 1) and added with stirring 1N ammonia water to pH 9.5. The resin is aspirated and the filtrate is evaporated in vacuo. The residue is crystallized by a little water. After twice recrystallization of water and subsequent drying in vacuo over phosphorus pentoxide, 9.4 g of thiomorpholine-6 (D, L) -methyl-5-one-3 (L) -carbonyl-L-histidyl-L-proline-methylamide are obtained. mp. 138-139 ° C. [α] p 4 = -48.0 ° (c - 1, methanol).

Example 2

Proceed as in Example 1D, however, using 11.4 g orotonic acid (anhydrous) instead of thiomorpholine-6 (D, L) -methyl-5-one-3 (L) carboxylic acid. The evaporation residue from the eluate from the ion exchanger is twice covered by ethanol / ether (4: 1) and once by ethanol. The dough product is then taken up in water and lyophilized. After further drying over phosphorus pentoxide, 5.4 g of orotyl-L-histidyl-L-24-proline-methylamide is obtained. The melting point is uncharacteristic, [α] D = -46.6 (0 = 1, methanol).

9 148902

The combined mother liquors are evaporated and covered with hot isopropanol several times. After drying in vacuo, an additional 3.6 g of the desired product is obtained.

Example 3

Proceed as in Example 1, but instead of using benzyloxycarbonyl-L-histidyl-L-proline-methylamide 35 g (0.073 mol) of benzyloxycarbonyl-L-histidyl-L-proline-cyclohexylamide and (as in e.g. 2) uses 11.4 g of orotic acid (anhydrous). Further purification of the purified product as in Example 1d with a cation exchanger is carried out by chromatography on a silica gel column and eluting with ethanol-water (5: 1). Evaporation of the eluate gives orotyl-L-24 o histidyl-L-proline-cyclohexylamide in a yield of 8.6 g. [A] p = -54.3 (c = 0.3, methanol).

Example 4 a) Proceed as in Example 1a, however, instead of methylamine, 20.0 ml of n-butylamine are reacted, which is reacted with 69.2 g of benzyloxycarbonyl-L-proline-N-hydroxysuccinimide ester. The final product is recrystallized from vinegar ester petroleum ether (100: 100). After drying in vacuo, 49.8 g (82%) of benzyloxycarbonyl-L-proline-n-butylamide are obtained, m.p. 84-85 ° C [α] 25 = -48.9 ° (c = 1, methanol).

b) 60.8 g of benzyloxycarbonyl-L-proline-n-butylamide is hydrogenated as in Example 1b in the presence of 11.6 ml of glacial acetic acid, after completion of hydrogenolysis 50 ral 4 N hydrochloric acid is added and worked up as described.

The L-proline-n-butylamide hydrochloride obtained after evaporation of the ethanol is used after drying in vacuo without further treatment in the next step.

c) Proceed as in Example 1c, however, instead of the L-proline-methylamide hydrochloride used therein, the L-proline obtained from 60.8 g of benzyloxycarbonyl-L-proline-n-butylamide obtained in Example 4b is used. -n-butyl amide hydrochloride. The residue obtained after evaporation of the filtered reaction mixture in vacuo is added with water and ammonia (to pH 9.5). Then it is extracted several times with vinegar ester. The combined acetic acid extracts are shaken several times with water, 10% soda solution and again with water. From the vinegar ester solution, after drying over sodium sulfate, the solvent is evaporated and dried in vacuo benzyloxycarbonyl-L-histidyl-L-proline-n-butylamide as a foamy-dried mass. Yield: 53 g (60%).

[α] D -47.6 ° (c = 1, methanol).

D) Proceed as in Example 1D, however, using 33.1 g of benzyloxycarbonyl-L-histidyl-L-proline-n-butylamide and (as in Example 2) 11.4 g of orotic acid. The eluate from the ion exchanger is evaporated in vacuo. The foamy product thus obtained is purified by chromatography on a silica gel column prepared in methanol (grain size 0.063-0.200 mm).

Elute with methanol. In this way, 10.8 g (33.4%) of α2-2 o morphic orotyl-L-histidyl-L-proline-n-butylamide is obtained. [α] D = -55.0 ° (c = 0.5, methanol).

Example 5

Proceed as in Example 1, however, using 35.2 g of benzyloxycarbonyl-L-histidyl-L-proline-n-hexylamide and (as in Example 2) 11.4 g of orotic acid. After evaporation of the dimethylformamide, the residue is taken up in methanol-water (1: 1) and treated as in Example 1D with a cation exchange resin. The evaporation residue from the eluate from the ion exchanger is added to 50 ml of water and dissolved by the addition of 4 N hydrochloric acid to pH 3. A slight haze is filtered off. The filtrate is evaporated in vacuo. The residue is twice recrystallized from water-saturated n-butanol. The thus obtained substance is dissolved in water and the solution is then extracted several times with n-butanol. The combined organic extracts are evaporated in vacuo to give, after drying, 7.9 g (21%) of orotyl-L-histidyl-L-proline-n-hexylamide hydrochloride, m.p. 180-185 ° C.

[α] p = -57.8 ° (c = 1, methanol).

The combined mother liquors are evaporated and subjected to countercurrent distribution in a system of n-butanol and water. In this way, an additional 5.7 g (15%) of the desired product is obtained.

Example 6 a) 24.9 g of benzyloxycarbonyl-L-proline are dissolved in 150 ml of absolute tetrahydrofuran, with stirring, 13.9 ml of triethylamine is added, cooled to -15 ° C and at this temperature a solution of 13 ml of chloroacetic acidobutyl ester is added dropwise in 50 ml. absolute tetrahydrofuran, stirring for a further 5 minutes at -15 ° C and then dripping at this temperature a solution of 10.1 ml of piperidine in 50 ml of absolute tetrahydrofuran. After further stirring for 2 hours at room temperature, evaporate in vacuo, take up the residue in vinegar ester and extract the vinegar ester solution with water, 5% potassium hydrogen sulfate solution, saturated sodium bicarbonate solution and water. After evaporation of the acetic acid solution dried over sodium sulfate, the residue is treated with ether and recrystallized from vinegar ester-petroleum ether (50:75). After drying, 21.2 g (67%) of benzyloxycarbonyl-L-proline piperidide is obtained, m.p. 92 ° C. [et] 33 = -21.9 ° (c = 1, methanol).

b) 63.2 g of benzyloxycarbonyl-L-proline piperidide are treated with hydrogen as in Example 1b in the presence of 11.6 ml of glacial acetic acid, after completion of hydrogenolysis 50 ml of 4 N hydrochloric acid is added and worked up as described. The L-pro-lin piperidide hydrochloride obtained after evaporation of the ethanol is used directly after drying in the next step.

c) Proceed as in Example 1c, however, instead of the L-proline-methylamide hydrochloride used therein, the L-proline-piperide obtained from 63.2 g of benzyloxycarbonyl-L-proline-piperidide used in Example 6b is used. hydrochloride. The residue obtained after evaporation of the filtered reaction mixture in vacuo is worked up in an analogous manner as in Example 4c. The oil formed after evaporation of the vinegar ester solution is dissolved in a little methanol and again precipitated by the addition of ether. After coating off the above solution and removing the solvent residues in vacuo, benzyloxycarbonyl-L-histidyl-L-proline piperidide is obtained as a foamy solidified mass. Yield: 46.5 g (51%). [α] 33 = -51.3 ° (c = 1, methanol).

d) Proceed as in Example 1, however, using 33.6 g of benzyloxycarbonyl-L-histidyl-L-proline-piperidide and (as in Example 2) 11.4 g of orotic acid (anhydrous). The eluate from the ion exchanger is evaporated in vacuo and lyophilized. The further purification is carried out by chromatography on a column of ethanol prepared from silica gel. Ethanol is eluted. 10.9 g (32%) of amorphous orotyl-L-histo-24-dyl-L-proline-piperidide is thus obtained. [α] D = -62.5 (c = 0.5, methanol).

Example 7 a) Proceed as in Example 6a, however, using 11.2 ml of benzylamine instead of the pipidine. For purification, recrystallized from vinegar ester petroleum ether (150: 150) several times. After drying in vacuo, 24.3 g (72%) of benzyloxycarbonyl-L-proline-benzylamide are obtained, m.p. 93-94 ° C. [α] 33 = -43.5 ° (c = 1, methanol).

b) 67.7 g of benzyloxycarbonyl-L-proline-benzylamide is dissolved in 300 ml of glacial acetic acid, this solution is added 240 ml of a 40% solution of hydrogen bromide in glacial acetic acid and stirred for 90 minutes at room temperature. Then it is evaporated in vacuo. The residue is dissolved in a little methanol and precipitated again by the addition of ether. After removing the above solution, the residue is rinsed twice with ether and then dried in vacuo. The L-proline-benzyl-amide hydrobromide thus obtained is used without further treatment in the next step.

c) The mixture is carried out in an analogous manner as in Example 1c, however, instead of using the L-proline methyl amide hydrochloride, in Example 7b, it uses from L-proline-benzylamide-derived 67.7 g of benzyloxycarbonyl-L-proline-benzylamide. hydrobromide. The reaction mixture is worked up as described in Example 4c. After evaporation of the acetic acid solution and drying in vacuo, benzyloxycarbonyl-L-histidyl-L-proline benzylamide is obtained as a foamy solidified mass. Yield 80.7 g (85%). [α] 33 = -39.1 ° (c = 1, methanol).

d) Proceed as in Example 1, however, using 35.6 g of benzyloxycarbonyl-L-histidyl-L-proline-benzylamide and (as in Example 2) 11.4 g of orotic acid. The evaporation residue from the eluate from the ion exchanger is purified by column chromatography as described in Example 4d. This gives 11.7 g (33.3%) of amorphous orotyl-L-histidyl-L-proline benzyl amide [α] 33 = -50.5 ° (c = 1, methanol).

Example 8 410 mg of thiomorpholine-6- (D, L) -methyl-5-one-3-carbonyl-L-histidyl-L-proline [m.p. Dissolve in water, add 1 ml of 1N hydrochloric acid and freeze-dry. The residue obtained and 126 mg of N-hydroxysuccinimide are dissolved in 12 ml of dimethylformamide and, with stirring at room temperature, a solution of 206 mg of N, N'-dicyclohexylcarbodiimide in 3.4 ml of tetrahydrofuran is added. After stirring at room temperature for 2 hours, the thus obtained solution of the ester of thiomorpholine-6- (D, L) -methyl-5-one-3-carbonyl-L-histidyl-L-proline and N-hydroxysuccinimide is added 2 ml. and approx.

40% aqueous methylamine solution. Stir for another 5-10 minutes at room temperature and then evaporate under reduced pressure. The residue is added to water and filtered. The filtrate is added to an equal volume of methanol and then worked up in the manner described in Example 1 to give the same product as Example 1 in a yield of 87 mg.

Example 9 587 mg of orotyl-L-histidine is dissolved in 25 ml of water with the addition of 2 ml of 1 N hydrochloric acid and then lyophilized. The residue and 288 mg of 1-hydroxybenzotriazole and 329 mg of L-proline-N-methylamide

Claims (1)

Dissolve hydrochloride in 10 ml of dimethylformamide. While stirring at room temperature, 0 566 ml of triethylamine and a solution of 412 mg of N, N'-dicyclohexylcarbodiimide in 7.4 ml of dimethylformamide are successively added. After stirring for another 15 hours at room temperature, the filtrate is filtered off and the filtrate is evaporated under reduced pressure. The residue is added to water and filtered and an equal volume of methanol is added to the filtrate. As in Example 1, one is treated with a cation exchange resin, washed with methanol and water and then eluted in methanol / water under ammonia addition to pH 9.5. The evaporation residue from the eluate is worked up as described in Example 2 to give the same product as in Example 2 in a yield of 289 mg. Example 10 Proceed as in Example 9, however, using 625 mg of thiomorpholine-6-methyl-5-one-3-carbonyl-L-histidine instead of the orotyl-L-histidine and the eluate obtained from the cation exchange resin as in Example ld. In this way the same product as in Example 1d is obtained in a yield of 257 mg. Analogous Process for the Preparation of TRH Analogous Derivatives of N-Substituted Histidyl Prolinamide of the General Formula I years in 2 \> .r1 cr \ C0 - NH CH- CO - N_L CO - H 1 2 wherein R and R are the same or different and (with the proviso that 1 2 not both symbols R and R may simultaneously mean hydrogen) represents hydrogen, alkyl groups of up to 6 carbon atoms or a cyclohexyl or benzyl group, or together with the nitrogen atom to which they are attached form a piperidine ring and Z represents one of the groups a) - NH - CO - CH- ( N = C-CH-) or R4 Ah R4 R6 b) -C-S -CHO-k5 wherein R together with R represents an additional bond between the carbon atoms to which they are attached or when Z is the group b ) R3 CC represents a hydrogen atom while R and R are the same or different and represent hydrogen or alkyl groups of 1-3 carbon atoms, or salts thereof with pharmaceutically useful acids, characterized in that a) reacting a compound of the general formula CH2 R1 ΗΛί - CH - CO - NL CO -, III A 'NT 1 2 wherein R and R have the above meanings, with a carboxylic acid having the general one formula - Z_ / n /> / 1 '' 'II' 'R3 C c "COOH H wherein R and Z have the above meanings, in the presence of a water-binding agent or with a functional derivative of an acid of formula II or b) reacting a compound of the general formula I for 3h i! R 3 V in X 10 - NH - CH - COOH H wherein R 2 and Z have the above meanings, in the presence of a water-binding agent, or a functional derivative of a compound of formula IV with a compound of the general formula