CS237326B2 - Process for preparing carboxyalkyldipeptides - Google Patents

Abstract

A method for preparing carboxyalkyl dipeptides of the general formula I O R, R3 R; Rs O R—C—C—NH—CH—C—N—C—C—Rg (I) I II I R2 o R? and their pharmaceutically acceptable salts and biologically active isomers, consisting in reacting a dipeptide of the general formula II with a compound of the general formula III. The substances of the formula I are useful as inhibitors of the converting enzyme and its antihypertensive agents.

Description

The invention relates to a method for preparing ^carboxyalkyl dipeptides of the general formula I

O Ri R3 R ₄ R5 O

II I I I I II

R—C—C—NH—CH—C—N—C—C—R _e (I)

I II I

R ₂ O R7 where

R and R _(i) are the same or different and represent a hydroxy group, an alkoxy group with 1 to 6 carbon atoms, an alkenoxy group with 1 to 6 carbon atoms, a dialkylaminoalkoxy group with 1 to 6 carbon atoms in the alkyl residue, an acylaminoalkoxy group with 1 to Θ carbon atoms in the alkyl residue and 2 to 12 carbon atoms in the acyl residue, an acyloxyalkoxy group with 1 to 6 carbon atoms in the alkyl residue and 2 to 12 carbon atoms in the acyl residue, an aryloxy group with at least G carbon atoms, an aralkyloxy group with 1 to 4 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue, a substituted aryloxy group with at least 6 carbon atoms or a substituted aralkoxy group with 1 to 3 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue, where the substituent is methyl, halogen or methoxy, amino, alkylamino with 1 to 6 carbon atoms, dialkylamino with 1 to 6 carbon atoms, aralkylamino with 1 to 4 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue or hydroxyamino,

R1 is hydrogen, alkyl of 1 to 20 carbon atoms, including branched acyclic groups, allyl, substituted alkyl of 1 to 4 carbon atoms, where 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 residue, 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, arylthio of at least 6 carbon atoms, carboxy, carboxamido, carbalkoxy of 1 to 3 carbon atoms, phenyl, substituted phenyl, where the substituent is alkyl of 1 to 3 atoms carbon, alkoxy group with 1 to 3 carbon atoms, or halogen, aralkyl with 1 to 4 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue or indolylalkyl with 1 to 3 carbon atoms in the alkyl residue, aralkenyl with 1 to 4 carbon atoms in the alkenyl residue and at least 6 carbon atoms in the aryl residue, substituted aralkyl with 1 to 3 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue, substituted indolylethyl, substituted aralkenyl with 1 to 3 carbon atoms in the alkenyl residue and at least 6 carbon atoms in the aryl residue, where the substituent is halogen or dihalogen, alkyl with 1 to 3 carbon atoms, hydroxy group, alkoxy group with 1 to 3 carbon atoms, amino group, aminomethyl, acylamino group with 2 to 12 carbon atoms, dialkylamino group with 1 to 3 carbon atoms in the alkyl residue, alkylamino group with 1 to 3 carbon atoms, carboxyl, haloalkyl with 1 to 3 carbon atoms, cyano- or sulfonamido group, aralkyl with 1 to 4 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue or indolylethyl, substituted on the alkyl part by an amino group or an acylamino group with 2 to 12 carbon atoms,

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

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

Rg 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, 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 or alkylthioalkyl of 1 to 6 carbon atoms in the alkyl radical, _R4 and _R5 are optionally joined together to form an alkylene bridge of 2 to 4 carbon atoms, an alkylene bridge of 2 to 3 carbon atoms and one sulfur atom, an alkylene bridge of 3 to 4 carbon atoms containing a double bond other than an alkylene bridge. a bridge of 2 to 4 carbon atoms substituted with hydroxy, alkoxy of 1 to 6 carbon atoms or alkyl of 1 to 6 carbon atoms, and their pharmaceutically acceptable salts and biologically active isomers.

Alkyl groups with 1 to 6 carbon atoms or alkenyl groups with 1 to 6 carbon atoms include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, hexyl or vinyl, allyl, butenyl and the like. Ar alkyl groups with 1 to 4 carbon atoms in the alkyl residue and

23732S 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 means phenyl or naphthyl. Heteroaryl groups include, for example, pyridyl, thienyl, furyl, indolyl, benzthienyl, imidazolyl and thiazolyl.

Substituted alkyl residues of the substituent R _x , R j and R ₅ are represented by groups such as

Í1 ir ^CH 2HO-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 _/( and R ₅ , when linked by the carbon and nitrogen atoms to which they are attached, form a 4- to 6-membered ring which may contain one sulfur atom or a double bond.

Preferred rings have the general formula

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

-G

Preferred are compounds of the general formula I, where R is a hydroxy group, an alkoxy group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, an aralkyloxy group with 1 to 4 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue, a dialkylamino group with 1 to 6 carbon atoms in the alkyl residue, an alkoxy group with 1 to 6 carbon atoms, an acylaminoalkoxy group with up to 6 carbon atoms in the alkyl residue and up to 12 carbon atoms in the acyl residue, an acyloxy group with 2 to 12 carbon atoms in the acyl residue, an acyloxy group with 2 to 12 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, where the substituent is methyl, halogen or methoxy,

R ₆ is a hydroxy or amino group,

R ₂ and R ₇ are hydrogen,

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

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

R _x has the meaning defined above.

More preferred compounds are those preferred compounds of general formula I, wherein

R1 is alkyl with 1 to 6 carbon atoms, substituted alkyl with 1 to 4 carbon atoms, where the substituent is an amino group, an arylthio group with at least 6 carbon atoms, an aryloxy group with at least 6 carbon atoms or an arylamino group with at least 6 carbon atoms, an aralkyl with 1 to 4 carbon atoms in the alkyl residue and at least 6 carbon atoms in the aryl residue or an indolylalkyl with 1 to 3 carbon atoms in the alkyl residue or a substituted aralkyl (phenylalkyl or naphthylalkyl) with 1 to 4 carbon atoms in the alkyl residue and a substituted indolylalkyl with 1 to 3 carbon atoms in the alkyl residue, where the substituent fy] is halogen, dihalogen, amino, aminoalkyl with 1 to 6 carbon atoms, hydroxy, alkoxy with 1 to 6 carbon atoms or alkyl with 1 to 6 carbon atoms.

Most preferred are compounds of general formula I, wherein

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

R ₆ is a hydroxy group,

R ₂ and R ₇ are hydrogen,

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

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

Rj is alkyl of 1 to 18 carbon atoms, substituted alkyl of 1 to 4 carbon atoms, where the substituent is an amino group, an arylthio group of at least 6 carbon atoms or an aryloxy group of at least 6 carbon atoms or an indolylalkyl group of 1 to 3 carbon atoms in the alkyl residue, such as indolylethyl, or substituted aralkyl (phenylalkyl or naphthylalkyl) of 1 to 4 carbon atoms in the alkyl residue and substituted indolylethyl, where the substituent (y) is halogen, dihalogen, amino, aminoalkyl of 1 to 6 carbon atoms, hydroxy, alkoxy of 1 to 6 carbon atoms or alkyl of 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 compounds of formula I is carried out by reacting a dipeptide of general formula II

R3 O Rz, 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, which may include suitable protection of any reactive group and R ₄ , R 6 and R ₇ are as defined above, with a compound of formula III

R,.

X—C—COR (III) r ₂ where

R1 is as defined above, which may include suitable protection of any reactive group and X is chlorine, bromine, iodine or sulfonyloxy R and _R2 are as defined above and then optionally removing the protecting groups to obtain a compound of formula I, where R and _R8 are as defined above except for hydroxy and Rj, _R2 , Rg, _R4 and _R7 are as defined above and optionally converting R and/or _R6 by hydrolysis or hydrogenation of a suitable intermediate to a hydroxy group and optionally preparing a salt thereof and optionally isolating the more biologically active isomer by chromatography or fractional crystallization.

The dipeptide of formula II is alkylated with a suitable α-halo acid (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 a benzyl ester of formula I, where Rg is benzyloxy and R is alkoxy, gives compounds of formula I, where R is alkoxy and _R6 is hydroxy, and where _R6 is alkoxy and R is benzyloxy, compounds of formula I, where R is hydroxy and R6 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 general formula I, the carbon atoms to which R _b R _;1 and R _s are attached may be asymmetric. Thus, compounds exist in diastereomeric forms or mixtures thereof. In the synthesis described above, racemates, enantiomers or diastereomers may be used as starting materials. When diastereomeric products are obtained in the synthetic procedures, these may be separated by conventional chromatographic or fractional crystallization methods. In general, partial structures in the S-configuration are preferred, i.e.

Oh R,

II I

R—C—C—NH—,

R ₂ ^R 3 —NH—CHCO— and

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, salts with amino acids such as arginine, lysine, and the like.

Salts can also be prepared with organic and inorganic acids, for example, 1-ICl, HBr, H ₂ SO ₄ , H _{; í} PO/„ methanesulfonic, toluenesulfonic, maleic, fumaric, camphorsulfonic acid. Non-toxic physiologically acceptable salts are preferred, although other salts are also useful, for example in the isolation or purification of the product.

Salts can 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 the salt is insoluble, or in a solvent such as water, which is then removed in vacuo or by freeze-drying or by exchanging the cations of the salt present for another cation on a suitable ion exchanger.

The compounds of the invention inhibit angiotensin converting enzyme and thus block the conversion of the decapeptide angiotensin I to angiotensin II. Angiotensin II is an active substance that increases blood pressure. The blood pressure-lowering effect may be derived from inhibition of its biosynthesis, especially in animals and humans whose hypertension is influenced by angiotensin II. The converting enzyme also degrades the vasodepressor substance bradykinin. Therefore, angiotensin converting enzyme inhibitors may also lower blood pressure by potentiating bradykinin. Although the relative importance of these and other possible mechanisms remains to be confirmed, angiotensin converting enzyme inhibitors are effective antihypertensive agents in various animal models and are useful clinically, 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).

The evaluation of inhibitors of the converting enzyme is carried out in an in vitro enzyme inhibition assay. For example, a useful method is described by Y. Piquilloud, A. Reinharz and M. Roth, Biochem. Biophys. Acta, 206, 136 (1970), which measures the hydrolysis of carbobenzyloxyphenylalanylhistidinyleucine.

In vivo evaluations are performed, for example, in normotensive rats administered angiotensin I according to the technique of J. R. Weeks and J. A. Jones, Proc. Soc. Exp. Biol. Med. 104, 646 (1960) or in the high-renin rat model as reported by S. Koletsky et al., Proc. Soc. Exp. Biol. Med. 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 a reduction in blood pressure by forming compositions such as tablets, capsules or elixirs for parenteral administration. The compounds of the invention can be administered to patients (animals and humans) in need of such treatment in a dosage range of 5 to 500 mg per patient administered several times a day, the total daily dose being in the range of 5 to 2000 milligrams. The dosage 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 are mixtures in which the individual daily doses range from one-fifth of the minimum recommended clinical doses to the maximum recommended levels for the condition in which they are administered individually. To illustrate such mixtures, one antihypertensive compound of the invention clinically effective in the range of 15 to 200 mg per day may be effectively combined at a level of 3 to 200 mg per day with the following antihypertensives and diuretics in the given daily dose range:

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, three-drug mixtures, such as hydrochlorothiazide (15 to 200 mg] plus amiloride (5 to 20 mg] + an angiotensin converting enzyme inhibitor of the invention (3 to 200 mg) or hydrochlorothiazide (15 to 200 mg) -1- timolol (5 to 50 mg) + angiotensin converting enzyme inhibitor of the invention (3 to 200 mg), are effective mixtures in the treatment of high blood pressure in hypertensive patients. The above dosage range is adjusted on a unit basis as needed to achieve a daily dose distribution.

The dose varies depending on the severity of the disease, the patient's weight, and other factors that will be evaluated by the doctor.

The above mixtures are formulated 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 mixed with a physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavoring agent, etc. in a unit dosage form according to accepted pharmaceutical practice. The amount of active ingredient in these mixtures or preparations is such that suitable doses within the given range are achieved.

Examples of adjuvants that can be incorporated into tablets, capsules, etc. are the following substances: a binder, such as tragacanth, gum arabic, corn starch or gelatin, an excipient, such as microcrystalline cellulose, a disintegrant, such as corn starch, pregelatinized starch, alginic acid or the like, a glidant, such as magnesium stearate, a sweetener, such as sucrose, lactose or saccharin, a flavoring, such as peppermint oil, evening primrose oil or cherry oil.

When used as a unit dosage form, a capsule may contain, in addition to the above-mentioned substances, a liquid carrier, such as a fatty oil. Various other materials may be included as a coating or 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 sweetening agent, methyl propyl paraben as a preservative, a coloring agent, and a flavoring agent, such as cherry or orange essential oil.

A sterile composition for injection 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. Buffers, preservatives, antioxidants, etc. may be included as necessary.

The following examples illustrate the process of the invention. The 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 XAD-2 polystyrene resin. Determine the 200-400 mesh fraction and load 440 ml onto a chromatography column. Equilibrate with 0.1 M _NH4OH in a 95:5 (v/v) water-methanol mixture. The column is charged with 350 milligrams of N-(1-carboxy-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 is adjusted to pH 7.5 with sodium hydroxide and treated overnight with sodium cyanoborohydride (0.32 g). Elute with the same solvent as above. The first isomer leaves the column in the volume range of 375 to 400 ml of eluent. The second isomer in the range of 440 to 480 ml, with intermediate fractions containing a mixture of isomers. The fraction containing the first isomer is lyophilized to obtain 130 mg of white solid. Recrystallization with 1 ml of water adjusted to pH 3 gives 94 mg of white needles, melting point 148-151 °C.

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

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

Example 2

N-carboxymethyl-L-alanyl-L-proline

In a small flask equipped with a pH electrode, mix 1.05 g of L-alanyl-L-proline and 1.2 ml of 4 M NaOH. Add 0.53 g of chloroacetic acid in 1.2 ml of 2 M NaOH; adjust the pH to 8 to 9, heat to 85 °C, and maintain the pH at 8 to 9 for 15 minutes by adding sodium hydroxide as needed. Add another 0.53 g of chloroacetic acid and the required amount of sodium hydroxide over 15 minutes. Add a third 0.53 g of chloroacetic acid, maintain the pH at 9 for 15 minutes, maintain at 85 °C for another 15 minutes, and cool.

The reaction mixture is passed through a column of Dowex 50 (H+), washed with water and eluted with 2% pyridine in water. Fractions showing a positive ninhydrin reaction are pooled, concentrated in vacuo to a small volume, and lyophilized.

This material is dissolved in a few ml of water and loaded onto a Dowex 50 (Na+) column. It is eluted with 0.5 M citric acid adjusted to pH 3.3 with sodium hydroxide. The desired product appears first (ninhydrin test), well distinct from unreacted alanylproline. The product fraction is concentrated in vacuo to a weight of about 300 g.

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

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

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

1.77—2.68 (wide m, 4H),

3.63 (s) over 3.28—3.92 (m), (total 4H),

4.05—4.72 (wide m, 2H) overlapped by 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 grams) and L-alanyl-L-proline (0.31 g) in water was adjusted to pH 7 with sodium hydroxide.

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

Purified by gel filtration (LH-20) for spectrographic analysis. The NMR spectrum in DMSO shows an aromatic hydrogen at 7.20, a broad singlet at 4.30, broad multiplets at 3.0-3.9, 2.67 and 1.94, and a 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