CS237326B2 - Method of preparation of carboxyalkyldipeptide - Google Patents

Abstract

Process for preparing carboxyalkyldipeptides of general interest of Formula I R, R, R; Rs O R — C — C — NH — C — N — C — C — Rg (I) I II I R2 o R? and pharmaceutically acceptable salts thereof and biologically of the active isomer in the reaction dipeptide of formula II with the compound of formula III. The compounds of formula I are useful as inhibitors converting enzyme and its antihypertensive agent.

Description

The invention relates to a method for preparing carboxylic xyalkyldipeptidů ¹ of the formula I

O R 1 R ₄ R 5 O

II. I

R — C — C — NH — CH — C — N — C — C — R _e (I)

I II I

R ₂ O R 7 where

R and R _(i) are the same or different and are hydroxy, (C1-C6) alkoxy, (C1-C6) alkenoxy, (C1-C6) dialkylaminoalkoxy, (C1-C6) acylaminoalkoxy) and 2 to 12 carbon atoms in the acyl radical, acyloxyalkoxy having 1 to 6 carbon atoms in the alkyl radical and 2 to 12 carbon atoms in the acyl radical, aryloxy of at least G carbon atoms, aralkyloxy of 1 to 4 carbon atoms in the alkyl radical and at least 6 aryl-substituted carbon atoms, substituted aryloxy of at least 6 carbon atoms or substituted aralkoxy of 1 to 3 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl radical, wherein the substituent is methyl, halogen or methoxy, amino, alkylamino of 1 to 6 carbon atoms, dialkylamino of 1 to 6 carbon atoms, aralkylamino of 1 to 4 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical or hydroxyamino group,

R 1 is hydrogen, alkyl of 1 to 20 carbon atoms which includes branched acyclic groups, allyl, substituted alkyl of 1 to 4 carbon atoms wherein the substituent is halogen, hydroxy, alkoxy of 1 to 3 carbon atoms, aryloxy of at least 6 carbon atoms , amino, alkylamino, dialkylamino of 1 to 3 carbon atoms in the alkyl radical, acylamino of 2 to 12 carbon atoms, arylamino of at least 6 carbon atoms, and guanidino, imidazoyl, indolyl, mercapto, alkylthio of 1 to 3 carbon atoms, at least 6 carbon atoms, carboxy, carboxamido, carbalkoxy of 1 to 3 carbon atoms, phenyl, substituted phenyl wherein the substituent is alkyl of 1 to 3 carbon atoms, alkoxy of 1 to 3 carbon atoms, or halogen, aralkyl of 1 to 4 atoms carbon in the alkyl radical and at least 6 carbon atoms in the aryl radical or indolylalkyl of 1 to 3 carbon atoms in the alkyl radical, aralkenyl of 1 to 4 alkenyl and at least 6 carbon atoms in the aryl radical, substituted aralkyl of 1 to 3 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical, substituted indolylethyl, substituted aralkenyl of 1 to 3 carbon atoms in the alkenyl radical and at least 6 carbon atoms in the aryl radical wherein the substituent is halogen or dihalogen, alkyl of 1 to 3 carbon atoms, hydroxy, alkoxy of 1 to 3 carbon atoms, amino, aminomethyl, acylamino of 2 to 12 carbon atoms, dialkylamino of 1 to 3 atoms C 1 -C 3 alkylamino, carboxyl, C 1 -C 3 haloalkyl, cyano or sulfonamido, C 1 -C 4 aralkyl and at least 6 C aryl or indolylethyl, substituted on the alkyl moiety with amino or acylamino of 2 to 12 carbon atoms,

R ₂ and R 7 are hydrogen or alkyl of 1 to 6 carbon atoms, R ₃ is hydrogen, alkyl of 1 to 6 carbon atoms, phenylalkyl of 1 to 6 carbon atoms, ammomethylphenylalkyl of 1 to 6 carbon atoms, hydroxyphenylalkyl of 1 up to 6 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, acetylaminoalkyl of 1-6 carbon atoms, acylaminoalkyl of 1-6 carbon atoms in the alkyl moiety and 2-12 carbon atoms in the acyl moiety, aminoalkyl of 1-6 carbon atoms; carbon atoms, dimethylaminoalkyl of 1 to 6 carbon atoms, haloalkyl of 1 to 6 carbon atoms, guanidinoalkyl of 1 to 6 carbon atoms, imidazolylalkyl of 1 to 6 carbon atoms, indolylalkyl of 1 to 6 carbon atoms, mercaptoalkyl of 1 to 6 carbon atoms and alkylthioalkyl of 1 to 6 carbon atoms in the alkyl radical,

R ₄ is hydrogen or alkyl of 1 to 6 carbon atoms,

R 8 is hydrogen, alkyl of 1 to 6, carbon atoms, phenyl, phenylalkyl of 1 to 6 carbon atoms, hydroxyphenylalkyl of 1 to 6 carbon atoms, hydroxyalkyl of 1 to 6 carbon atoms, aminoalkyl of 1 to 6 carbon atoms. (C 1 -C 6) guanidinoalkyl, (C 1 -C 6) imidazolylalkyl, (C 1 -C 6) indolylalkyl, (C 1 -C 6) mercaptoalkyl or (C 1 -C 6) alkylthioalkyl, R ₄ and R ₅ are optionally linked together to form a C 2 -C 4 alkylene bridge, C 2 -C 3 alkylene bridge with one sulfur atom, a C 3 -C 4 alkylene bridge containing a double bond of a C 2-4 alkylene unsubstituted C 2 -C 4 alkylene bridge, C 1 -C 6 alkoxy or C 1 -C 6 alkyl, and pharmaceutically acceptable salts and biologically active isomers thereof.

C 1 -C 6 alkyl or C 1 -C 6 alkenyl include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl or vinyl, allyl, butenyl and the like. C1-C4 groups in the alkyl radical; and

23732S with at least 6 carbon atoms in the aryl radical include, for example, benzyl, p-methoxybenzyl and the like.

Halogen means chlorine, bromine, iodine or fluorine. Aryl represents phenyl or naphthyl. Heteroaryl groups include, for example, pyridyl, thienyl, furyl, indolyl, benzthienyl, imidazolyl and thiazolyl.

Substituted alkyl residues of R _x, R and R ₅ is shown as moieties

I1 ir 2HO ^CH-CH ₂ - HS-CH ₂ -, H ₂ N- (CH _{2) 4} -, CH ₃ -S- (CH _{2] 2-,} H ₂ N- (CH _{2) 3} -,

NH

II

H ₂ N - C - NH - (CH ₂ ) ₃ - and the like.

R _{1 (} and R ₅ , when connected by a carbon and nitrogen atom to which they are attached) form a 4- to 6-membered ring which may contain a single sulfur atom or a double bond.

Preferred rings have the general formula

where ¥ is CH ₂ , S or CHOCH ₃ , or the formula

-G

Preferred are compounds of formula (I) wherein R is hydroxy, (1-6C) alkoxy, (1-6C) alkoxy, (1-4C) aralkyloxy, and at least 6 (aryl) aryl, (1- (1-6C) dialkylamino). up to 6 carbon atoms in the alkyl radical, alkoxy of 1 to 6 carbon atoms, acylaminoalkoxy of up to 6 carbon atoms in the alkyl radical and up to 12 carbon atoms in the acyl radical, acyloxy of 2 to 12 carbon atoms in the acyl radical carbon atoms, alkoxy of 1 to 6 carbon atoms, wherein the substituent is methyl, halogen or methoxy;

R ₆ is hydroxy or amino,

R ₂ and R ₇ are hydrogen,

R ₃ is alkyl of 1 to 6 carbon atoms or aminoalkyl of 1 to 6 carbon atoms,

R ₄ and R 5 are joined to form preferred rings as above wherein Y is CH ₂ , S or CH-OCH 3,

R _x is as defined above.

More preferred compounds are those preferred compounds of formula I wherein

R 1 is alkyl of 1 to 6 carbon atoms, substituted alkyl of 1 to 4 carbon atoms wherein the substituent is amino, arylthio of at least 6 carbon atoms, aryloxy of at least 6 carbon atoms or arylamino of at least 6 carbon atoms, aralkyl of 1 to 6 carbon atoms 4 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical or indolylalkyl of 1 to 3 carbon atoms in the alkyl radical or substituted aralkyl (phenylalkyl or naphthylalkyl) of 1 to 4 carbon atoms in the alkyl radical and substituted indolylalkyl of 1 to 3 atoms carbon in an alkyl moiety wherein the substituent phyl is halogen, dihalogen, amino, C 1 -C 6 aminoalkyl, hydroxy, C 1 -C 6 alkoxy, or C 1 -C 6 alkyl.

Most preferred are compounds of formula I wherein

R is a hydroxy or alkoxy group having 1 to 6 carbon atoms,

R ₆ is hydroxy,

R ₂ and R ₇ are hydrogen,

R ₃ is methyl or aminoalkyl of 1 to 6 carbon atoms,

R ₄ and R ₃ are linked by a carbon atom and a nitrogen atom to form proline, 4-thioproline, or 4-methoxyproline,

R 1 is alkyl of 1 to 18 carbon atoms, substituted alkyl of 1 to 4 carbon atoms wherein the substituent is amino, arylthio of at least 6 carbon atoms or aryloxy of at least 6 carbon atoms or indolylalkyl of 1 to 3 carbon atoms in the alkyl radical, such as indolylethyl, or substituted (C1-C4) aralkyl (phenylalkyl or naphthylalkyl) and substituted indolylethyl, wherein substituent (s) is halogen, dihalogen, amino, (C1-C6) aminoalkyl, hydroxy, (C1-C6) alkoxy or alkyl having 1 to 6 carbon atoms.

Preferred, more preferred and most preferred compounds also include pharmaceutically acceptable salts.

The compounds of the invention are useful as converting enzyme inhibitors and as antihypertensives.

The process for preparing the compounds of formula I is carried out by reacting the dipeptide of formula II

R3 O R2, Rg

I III I

H ₂ N — CH — C — N — C — COR ₆ (II) r ₇ where

R ₃ and R ₅ are as defined above, and may include appropriate protection of any reactive group, and R ₄ , R 8 and R ₇ are as defined above, with a compound of formula III

R ,.

X - C - COR (III) r ₂ where

R 1 is as defined above, and may include appropriate protection of any reactive group and X is chloro, bromo, iodo or sulfonyloxy, R 1 and R ₂ are as defined above, and then optionally deprotected to give a compound of formula I wherein R and R ₈ are as defined above except hydroxy, and R, _R2, Rg, _R4, and _R7 are as defined above and optionally converted R and / or R ₆ by hydrolyzing or hydrogenating the appropriate intermediate to hydroxy, and optionally prepared as a salt and optionally isolating the more biologically active isomer by chromatography or fractional crystallization.

The dipeptide of formula (II) is alkylated with a suitable N-haloacid (ester or amide) or α-sulfonyloxy acid (ester or amide) of formula III under basic conditions in water or an organic solvent.

Reductive cleavage of the benzyl ester of formula I wherein Rg is benzyloxy and R is alkoxy, to obtain a compound of formula I wherein R is alkoxy and R ₆ is hydroxy and R ₆ is alkoxy and R is benzyloxy, the compound of formula I wherein R is hydroxy and R e is alkoxy.

The starting materials required for the above process are known in the literature or can be prepared by known methods from known starting materials.

In the product of formula (I), the carbon atoms to which R _b R ₁₁ and R 8 _are attached may be asymmetric. Thus, the compounds exist in diastereomeric forms or mixtures thereof. Racemates, enantiomers or diastereomers can be used as starting materials in the synthesis described above. When rheomeric products are obtained in the synthetic procedures of diastere8, these can be separated by conventional chromatographic or fractional crystallization methods. In general, partial structures, ie.

O R,

II I

R — C — C — NH—,

R ₂ ^R 3 —NH — CHCO— a

R ₄ R ₅ O —N — C — C—

R ₇ amino acids of formula I.

The compounds of the invention form salts with various inorganic and organic acids and bases, which are also included within the scope of the invention. These salts include ammonium salts, alkali metal salts such as sodium and potassium, which are preferred, alkaline earth metal salts such as calcium and magnesium salts, salts with organic bases such as dicyclohexylamine salts, N-methyl-D-glucamine, amino acid salts, such as arginine, lysine and the like.

May also be prepared salts with organic and inorganic acids such as L-ICI, HBr, H ₂ SO _4, H _i PO / "methanesulfonic, toluenesulfonic, maleic, fumaric, camphorsulfonic. Preferred are non-toxic physiologically acceptable salts, although other salts are also useful, for example, in isolating or purifying the product.

Salts may be formed by conventional methods, such as by reacting the free acid or free base of the product with one or more equivalents of a suitable base or acid in a solvent or medium in which it is present. a salt insoluble, or in a solvent such as water, which is then removed in vacuo or by freeze-drying or by cation exchange of the salt present with another cation on a suitable ion exchanger.

The compounds of the invention inhibit angiotensin converting enzyme and thus block the conversion of the angiotensin I decapeptide to antigiotensin II. Angiotensin II is an active substance that increases blood pressure. The blood pressure lowering effect may be derived from inhibition of its biosynthesis, particularly in animals and humans whose hypertension is affected by angiotensin II. Further, the converting enzyme breaks down the vasodepressor bradykinin. Therefore, angioten237326 sin converting enzyme inhibitors can also reduce blood pressure by potentiating bradykinin. Although the relative importance of these and other possible mechanisms must be confirmed, angiotensin converting enzyme inhibitors are effective antihypertensive agents in various animal models and are clinically useful, for example, in many patients in human therapy with renovascular, malignant and essential hypertension. See, for example, D. W. Cushman et al., Biochemistry 16, 5484 (1977).

Evaluation of converting enzyme inhibitors is performed in an in vitro enzyme inhibition assay. For example, a useful method is reported by Y. Piquilloud, A. Reinharz and M. Roth, Biochem. Biophys. Acta, 206, 136 (1970), by which the hydrolysis of carbobenzyloxyphenylalanylsthidinyl leucine is measured.

For example, in vivo evaluations are performed in normal pressure rats administered angiotensin I according to the technique of J. R. Weeks and J. A. Jones, Proc. Soc. Exp. Biol. Copper. 104, 646 (1960) or in the high renin rat model, as reported by S. Koletsky et al., Proc. Soc. Exp. Biol. Copper. 125, 96 (1967).

The compounds of the invention are useful as antihypertensives in the treatment of hypertensive mammals, including humans, and can be administered to achieve blood pressure lowering by forming into compositions such as tablets, capsules, or elixirs for parenteral administration. The compounds of the invention may be administered to patients (animals and humans) in need of such treatment in a dosage range of 5 to 500 mg per patient when administered several times a day, with a total daily dose ranging from 5 to 2000 milligrams. The dose will vary depending on the severity of the disease, the weight of the patient and other factors as determined by the physician.

The compounds of the invention may also be administered in admixture with other diuretics or antihypertensives. Typical compositions are those whose individual daily doses range from one fifth of the minimally recommended clinical doses to the maximum recommended levels for a single administration condition. To illustrate these compositions, one antihypertensive agent of the invention clinically effective in the range of 15 to 200 mg per day can be effectively mixed at a level in the range of 3 to 200 mg per day with the following antihypertensive agents and diuretics over a given dose range per day:

hydrochlorothiazide (15 to 200 mg), chlorothiazide (125 to 2000 mg), ethacrynic acid (15 to 200 mg), amiloride (5 to 20 mg), furosemide (5 to 80 mg), propanolol (20 to 480 mg), timolol (5 to 50 mg), and methyldopa (65 to 2000 mg). In addition, mixtures with three drugs such as hydrochlorothiazide (15-200 mg) plus amiloride (5-20 mg) + converting enzyme inhibitor of the invention (3-200 mg) or hydrochlorothiazide (15-200 mg) -1-timolol (5 up to 50 mg) + converting enzyme inhibitor of the invention (3 to 200 mg), an effective composition for the treatment of hypertension in hypertensive patients, The above dosage range is adjusted on a unit basis as necessary to achieve a daily dose distribution.

The dose will vary depending on the severity of the disease, the weight of the patient and other factors that will be evaluated by the physician.

The above mixtures are formed into pharmaceutical preparations as described below.

About 10 to 500 mg of a compound or mixture of compounds of Formula I or a physiologically acceptable salt is admixed with a physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavoring, etc. in unit dosage form according to accepted pharmaceutical practice. The amount of active ingredient in such compositions or compositions is such that appropriate dosages within the range will be achieved.

Examples of adjuvants that can be incorporated into tablets, capsules and the like are the following: a binder such as tragacanth, acacia, corn starch or gelatin, an excipient such as microcrystalline cellulose, a disintegrant such as corn starch, pregelatinized starch, alginic acid and the like; a glidant such as magnesium stearate; a sweetener such as sucrose, lactose or saccharin; an aromatic agent such as peppermint oil, wintergreen oil or cherry oil.

When used as a unit dosage form of a capsule, it may contain, in addition to the above, a liquid carrier such as a fatty oil. Various other materials may be included as a coating or may otherwise modify the physical form of the dosage unit. For example, tablets may be coated with shellac, sugar, or both. A syrup or elixir may contain the active compound, sucrose as a sweetener, methyl propylparaben as a preservative, a coloring agent and a flavoring such as cherry or orange essential oil.

The sterile injectable mixture may be formulated according to conventional pharmaceutical practice by dissolving or suspending the active ingredient in a vehicle, such as water for injection, a naturally occurring vegetable oil, such as sesame oil, coconut oil, peanut oil, cottonseed oil etc. or a synthetic fatty vehicle. such as ethyl oleate or the like. Depending on the needs, buffers, preservatives, antioxidants and the like can be incorporated.

The following examples illustrate the process of the invention. Preferred diastereomers of these examples are isolated by column chromatography or traction crystallization.

Example 1

N- (1-carboxy-3-phenylpropyl) -L-alanyl-L-proline

Grind and sieve with XAD-2 polystyrene resin. A 200-400 mesh fraction is determined and 440 ml is loaded onto a chromatography column. Equilibrate with 0.1 M NH ₄ OH in a 95: 5 water / methanol (v / v) mixture. The column is packed with 350 mg of N- (1-caroxy-3-phenylpropyl) -L-alanyl -L-proline, dissolved in 10 ml of the same solvent, prepared as follows: A mixture of 4-phenyl-2-oxobutyric acid (1.49 g) and L-alanyl-L-proline (0.31 g) in water was treated with hydroxide. sodium pH 7.5 and treated overnight with sodium cyanoborohydride (0.32 g). Eluted with the same solvent as above. The first isomer exits the column in a volume range of 375-400 ml of eluent. The second isomer in a range of 440-480 ml. Fractions containing the first isomer were lyophilized to give 130 mg of a white solid, and recrystallized with 1 ml of water adjusted to pH 3 to give 94 mg of white needles, m.p. 148-151 ° C.

This is the more efficient isomer and has the S, S, S configuration as determined by X-ray; [α] _D = -67.0 °, (0.1 M HCl after drying under vacuum with phosphorus pentoxide. NMR spectrum (DMSO) shows a single doublet for methyl protons at 1.22 ppm. Lyophilization of the fraction containing the second isomer yields 122 milligrams. Recrystallization of 103 mg of 2.5 ml of water adjusted to pH 3 gave 64 mg of feather white crystals, m.p. 140-145 ° C, [α] _D = -101.6 ° (0.1 M HCl). drying.

NMR spectrum (DMSO) shows methyl doublet at 1.17 ppm.

Example 2

N-carboxymethyl-L-alanyl-L-proline

In a small flask equipped with a pH electrode, 1.05 g of L-alanyl-L-proline and 1.2 ml of 4 M NaOH were mixed. 0.53 g of chloroacetic acid in 1.2 ml of 2 M NaOH are added; The pH is adjusted to 8-9, heated to 85 ° C and maintained at pH 8-9 by adding sodium hydroxide as needed for 15 minutes. Add an additional 0.53 g of chloroacetic acid and the necessary amount of sodium hydroxide over 15 minutes. 0.53 g of chloroacetic acid is added a third time, the pH is maintained at up to 9 minutes for 15 minutes, maintained at 85 ° C for a further 15 minutes and cooled.

Pass the reaction mixture through a Dowex 50 (H +) column, wash with water and elute with 2% pyridine in water. Fractions showing a positive ninhydrin reaction were combined, concentrated in vacuo to a small volume, and lyophilized.

This material was dissolved in a few ml of water and loaded onto a Dowex 50 (Na +) column. Elute with 0.5 M sodium hydroxide adjusted to pH 3.3 with sodium hydroxide. The desired product is the first (ninhydrin assay), well different from unreacted alanylproline. The product fraction was concentrated in vacuo to a weight of about 300 g.

This solution is loaded onto a Dowex 50 (H +) column. Wash with water, then elute the product with 2% pyridine in water. The product fraction was concentrated in vacuo to a small volume and lyophilized. 417 mg of N-carboxymethyl-L-alanyl L-proline are obtained.

NMR Spectrum (D ₂ O, MeOH internal standard):

1.58 ppm (d, 1 = 6) with a small fraction at 1.53 (d, J = 6) (total 3H),

1.77-2.68 (broad m, 4H)

3.63 (s) above 3.28-3.92 (m), (total 4H),

4.05-4.72 (broad m, 2H) overlaid with a water peak at 4.68.

Example 3

N- (1-carboxy-3-phenylpropyl) -L-alanyl-L-proline

A mixture of 4-phenyl-2-oxobutyric acid (1.49 g) and L-alanyl-L-proline (0.31 g) in water was adjusted to pH with sodium hydroxide.

7.5 and treated with sodium cyanoborohydride (0.32 g) overnight. The product was adsorbed on a strongly acidic ion exchanger and eluted with 2% pyridine in water to give 0.36 g of crude diastereomeric product, N- (1-carboxy-3-phenylpropyl) -L-alanyl-L-proline.

Purify by gel filtration (LH-20) for spectrographic analysis. The NMR spectrum in DMSO shows aromatic hydrogen at 7.20, broad singlet at 4.30, broad multiplets at 3.0-3.9, 2.67 and 1.94 and doublet at 1.23 and 1.15. The mass spectrum shows a molecular ion at 492 m / e for the ditrimethylsilylated species.

Claims (1)

P R'ED TΕ T A process for the preparation of carboxyalkyldipeptides of the formula I O Rj R ;; R ₄ Rg O R — C — C — NH — CH — C — N — C — C — R ₆ (I) I II I r ₂ or ₇ where R and R _they are the same or different and are hydroxy, alkoxy of 1 to 6 carbon atoms, alkenoxy having 1 to 6 carbon atoms, dialkylaminoalkoxy having 1 to 6 carbon atoms in the alkyl radical, acylaminoalkoxyskupinu having 1 to 6 carbon atoms in the alkyl radical and 2 to 12 carbon atoms in the acyl radical, acyloxyalkoxy of 1 to 6 carbon atoms in the alkyl radical and 2 to 12 carbon atoms in the acyl radical, aryloxy of at least 6 carbon atoms, aralkyloxy of 1 to 4 carbon atoms in the alkyl radical and at least 6 atoms a substituted aryl aryloxy group having at least 6 carbon atoms or a substituted aralkoxy group having 1 to 3 carbon atoms in the alkyl group and at least 6 carbon atoms in the aryl group wherein the substituent is methyl, halogen or methoxy, amino, alkylamino having 1 to 6 atoms C 1 -C 6 dialkylamino, C 1 -C 4 aralkylamino in the alkyl radical and at least 6 carbon atoms in the aryl radical or hydroxyarino, R 1 is hydrogen, alkyl of 1 to 20 carbon atoms which includes branched acyclic groups, allyl, substituted alkyl of 1 to 4 carbon atoms, wherein the substituent is halogen, hydroxy, alkoxy of 1 up to 3 carbon atoms, aryloxy of at least 6 carbon atoms, amino, alkylamino, dialkylamino of 1 to 3 carbon atoms in the alkyl radical, acylamino of 2 to 12 carbon atoms, arylamino of at least 6 carbon atoms, and guanidino, imidazolyl, indolyl, mercapto , (C 1 -C 3) alkylthio, (C 1 -C 3) arylthio, carboxy, carboxamido, (C 1 -C 3) carbalkoxy, phenyl, substituted phenyl, wherein the substituent is (C 1 -C 3) alkyl, (C 1 -C 3) alkoxy carbon or halogen, aralkyl having 1 to 4 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical or ind. (C 1 -C 3) -alkylalkyl, (C 1 -C 4) -alkenyl and at least 6 C-aryl-substituted, (C 1 -C 3) -substituted alkyl in alkyl and at least 6 C-aryl , substituted indolylethyl, substituted aralkenyl of 1 to 3 carbon atoms in the alkenyl radical and at least 6 carbon atoms, in the aryl radical wherein the substituent is halogen or dihalogen, alkyl of 1 to 3 carbon atoms, hydroxy, alkoxy of 1 to 3 carbon atoms , amino, aminomethyl, C 2 -C 12 acylamino, C 1 -C 3 dialkylamino, C 1 -C 3 alkylamino, carboxyl, C 1 -C 3 haloalkyl, cyano- or sulphonamido, aralkyl 1-4 carbon atoms in the alkyl moiety and at least 6 carbon atoms in the aryl moiety or indolylethyl substituted on the alkyl moiety with amino or acylamine C 2 -C 12 R ₂ and R ₇ are hydrogen or alkyl of 1 to 6 carbon atoms, R ₃ is hydrogen, alkyl of 1 to 6 carbon atoms, phenylalkyl of 1 to 6 carbon atoms, aminomethyl-phenylalkyl of 1 to 6 carbon atoms, hydroxyphenylalkyl of 1 up to 6 carbon atoms, hydroxyalkyl of 1 to 6 carbon atoms, acetylaminoalkyl of 1 to 6 carbon atoms, acylaminoalkyl of 1 to 6 carbon atoms in the alkyl and 2 to 12 carbon atoms of the acyl residue, aminoalkyl of 1 to 6 carbon atoms, dimethylaminoalkyl C 1 -C 6 haloalkyl, C 1 -C 6 haloalkyl, C 1 -C 6 guanldinoalkyl, C 1 -C 6 imidazolylalkyl, C 1 -C 6 indolylalkyl, C 1 -C 6 indercaptoalkyl and C 1 -C 6 alkylthioalkyl up to 8 carbon atoms in the alkyl radical, R ₄ is hydrogen or alkyl of 1 to 6 carbon atoms, R ₃ is hydrogen, alkyl of 1 to 8 carbon atoms, phenyl, phenylalkyl of 1 to 6 carbon atoms, hydroxyphenylalkyl of 1 to 6 atoms C 1 -C 6 hydroxyalkyl, C 1 -C 6 hydroxyalkyl C 1 -C 6 guanidinoalkyl, C 1 -C 6 imidazolylalkyl, C 1 -C 6 indolylalkyl, C 1 -C 6 mercaptoalkyl or C 1 -C 6 alkylthioalkyl, R ₄ and R _{4 5} are optionally joined together to form a C 2 -C 4 alkylene bridge, C 2 -C 3 alkylene bridge, a C 1 -C 4 alkylene bridge or a C 2 -C 4 allylene bridge hydroxy, C 1 -C 6 alkoxy or C 1 -C 6 alkyl, and pharmaceutically acceptable salts and biologically active isomers thereof, characterized in that the dipeptide of the formula II is reacted 237 Rs OR ₄ R5 I II H ₂ N — CH — C — N — C — COR ₆ (II) R ₇ where R ₃ and R ₅ are as defined above and may include appropriate protection of any reactive group and R ₄ , R ₆ , R 7 are as defined above, with a compound of formula III X - C - COR (III) wherein R ₁ is as defined above, and may include appropriate protection of any reactive group and X is chlorine, thunder, iodine or sulfonyloxy, and R and R ₂ are as defined above, and then optionally deprotected to give a compound of formula I wherein R and R ₆ are as defined above except for hydroxy and R @ _b R @ _2, R _3, R _4, R ₅ and R ₇ are as defined above and optionally converted R and / / or R ₆ by hydrolyzing or "hydrogenation of the appropriate intermediate to hydroxy and optionally preparing a salt thereof and optionally isolating the more biologically active isomer by chromatography or fractional crystallization. R ₂