CS237327B2 - Method of preparation of carboxyalkyl dipeptide - Google Patents

Description

The invention relates to a process for the preparation of carboxyalkyldipeptides of the formula I

OR, R ₃ R ₄ R ₅ O r_C -C-NH-CH-C-N-C-C-R ₆ (I)

I II I

Ø2 o R7 where

R and R _c are identical or different and represent hydroxy, alkoxy of 1 to 6 carbon atoms, alkenoxy with X to 6 carbon atoms, dialkylaminoalkoxy having 1 to 6 carbon atoms in the alkyl radical, acylaminoalkoxyskupinu 1 to 6 and rucksack atoms in the alkyl residue 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 the C1 -C4 alkyl radical and at least 6 carbon atoms in the aryl radical, substituted aryloxy of at least 6 carbon atoms or substituted aralkoxy of 1 to 3 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical wherein the substituent is methyl, halogen or methoxy, amino, alkylamino of 1 up to 6 carbon atoms, dialkylamino of 1 to 6 carbon atoms, aralkylamino of 1 to 4 carbon atoms in the alkyl radical u and at least 6 carbon atoms in the aryl radical or a 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, imidazolyl, indolyl, mercapto, alkylthio of 1 to 3 carbon atoms, arylthio 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 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, aralkenyl of 1 to 3 4 carbon atoms in the alkenyl radical 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, hydroxy, alkoxy of 1 C 1 -C 3 alkyl, 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 C 2 -C 12 acylamino,

R2 and R7 are hydrogen or alkyl of 1 to 6 carbon atoms,

R ₃ is hydrogen, alkyl of 1 to 6 carbon atoms, phenylalkyl of 3 to 6 carbon atoms, aminomethyl-phenylalkyl of 1 to 6 carbon atoms, hydroxyphenylalkyl of 1 to 6 carbon atoms, hydroxyalkyl of 1 to 6 carbon atoms, acetylaminoalkyl (C 1 -C 6) acylaminoalkyl (C 1 -C 6) alkyl and 2 to 12 C-acyl radicals, (C 1 -C 6) aminoalkyl, (C 1 -C 6) dirlamino amino (C 1 -C 6) haloalkyl C 1 -C 6 guanidinoalkyl, C 1 -C 6 imidazolylalkyl, C 1 -C 6 indolylalkyl, C 1 -C 6 mercaptoalkyl and C 1 -C 6 alkylthioalkyl,

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

R ₃ is hydrogen, alkyl of 1 to 6 carbon atoms, phenyl, phenylalkyl of 1 to 6 carbon atoms, hydroxyphenylalkyl of 3 to 6 carbon atoms, hydroxyalkyl of 1 to 6 carbon atoms, aminoalkyl of 1 to 6 carbon atoms, guanidinoalkyl of 1 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 8 are optionally joined together to form (C 2 -C 4) alkylene, (C 2 -C 3) alkylene bridge, (C 3 -C 4) double bond alkylene or (C 2 -C 4) alkylene bridge substituted by hydroxy, (C 1 -C 6) alkoxy carbon atoms 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 Aralkyl groups having 1 to 4 carbon atoms in the alkyl radical and 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 radicals of R _b, R ₃ and R ₅ are represented by the groups as

HO-CH ₂ -, HS-CH? -, H ₂ N- (CH _{2) 4} -, CH ₃ -S- (CH _{2) 2} -, H ₃ N- (CH _{2) 3} -,

NH

II

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

R ₄ and R ₄ 'when connected by a carbon and nitrogen atom to which they are attached form a 4- to 6-membered ring which may contain one atom. sulfur or double bond.

Preferred rings have the general formula

wherein Y is CH ₂ , S or CHOCH ₃ , or the formula

Preferred are compounds of formula I wherein

R is hydroxy, C 1 -C 6 alkoxy, C 1 -C 6 alkoxy, C 1 -C 4 aralkyloxy of at least 6 carbon atoms in the aryl radical, C 1 -C 6 dialkylamino, C 1 -C 6 alkoxy, C 1 -C 6 acylaminoalkoxy and C 2 -C 12 acyl, C 2 -C 12 acyloxy, C 1 -C 6 alkoxy wherein the substituent is methyl, halogen or a methoxy group,

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 8 are joined to form the preferred rings as above wherein Y is CH 3, S or

CH — OCH ₃ ,

R 1 is as defined above.

More preferred compounds are those preferred compounds of formula I wherein

R ₁ is alkyl of 1 to 8 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 4 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical or indolylalkyl having 1 to 3 carbon atoms in the alkyl radical; substituted C1-C4-aralkyl (phenylalkyl or naphthylalkyl) and substituted C1-C3-indolylalkyl in the alkyl radical, wherein the substituent (yj is halogen, dihalogen, amino, C1-C6 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 ₇ and R ₇ are hydrogen,

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

R ₄ and R ₅ are joined by a carbon atom and a nitrogen atom to form proline, 4-thiaproline, 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 (C 1 -C 4) aralkyl (phenylalkyl or naphthylalkyl) and substituted indolylethyl, wherein the substituent (s) is halogen, dihalogen, amino, C 1 -C 6 aminoalkyl, hydroxy, C 1 -C 6 alkoxy C 1 -C 6 alkyl or C 1 -C 6 alkyl.

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 an amine of formula II

O Rl

II I

R - C - C - NH ₂ (II) r ₃ wherein R ₍ as defined above, and may include appropriate protection of any reactive group and R and R ₂ are as defined above, with a ketone of formula III

R 6 is R 8, R 8

O = C — C — N — C — CO — R _o (ΪΠ)

R ₇ wherein _R and R ₅ are as defined above, and may include suitable protection of any reactive groups, and the R / "R ₆ and R ₇ have the abovementioned meaning, then optionally the protective group is removed to give the compound of formula I wherein R 1 and R 2 _(i) are as defined above in addition to the hydroxy group, and R _h R ₂ , R ₃ , R ₄ , R ₅ and R ₇ are as defined above and optionally converted into R and / or Rf by hydrolysis or hydrogenation of the appropriate intermediate optionally preparing a salt thereof and optionally recovering the more biologically active isomer by chromatography or fractional crystallization.

The amino acid (or ester, amide or hydroxamic acid) of formula II is condensed with a ketone of formula III in an aqueous solution, preferably near neutral, or in a suitable organic solvent (e.g. CH ₂ CN) in the presence of sodium cyanoborohydride to give a compound of formula I _(R2 = H).

In a particular case where R 1 has a α-amino substituent, carbonyl and amine groups can normally be protected as β-lactam functions.

When R @ 1 and R _{@ 1} is a carboxyl protecting group, such as an alkoxy group or a benzyloxy group or the like, it can be converted by known methods, such as hydrolysis or hydrogenation, to a compound of formula I wherein R and / or R _{@ 1} is hydroxy.

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

In the products of formula (I), the carbon atoms to which R _b R 8 ₍ and R 8 attached) may be asymmetric. Thus, compounds exist in diastereoisomeric 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 synthetic processes, they can be separated by conventional chromatographic or fractional crystallization methods.

O Rj

II I

R — C — C — NH—,

I r ₃

R.) —NH — CHCO— a

R 1, R 3 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. Salts with organic and inorganic acids such as HCl, HBr, H ₂ SO ₄ , H ₃ PO ₄ , methanesulfonic, toluenesulfonic, maleic, fumaric, camphorsulfonic acid can also be prepared. Non-toxic physiologically acceptable salts are preferred, 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 environment in which the salt is insoluble or in a solvent such as water, which is then removed under vacuum or sublimation. drying or exchanging the cations 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 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, particularly in animals and humans whose hypertension is affected by angiotensin II. Further, the converting enzyme breaks down the vasodepressor bradykinin. Therefore, angiotensin converting enzyme inhibitors may 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 renoivascular, malignant, and essential hypertension. For example, D. W. Cushman et al., Biochemistry 16, 5484 (1977).

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

For example, in vivo evaluations are performed in normal pressure rats administered angiotensin I, according to the technique). 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, the total daily dose being in the range of 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 mgj), chlorothiazide (125 to 2000 mgj, ethacrynic acid (15 to 200 mg), amiloride (5 to 20 milligrams), furosemide (5 to 80 mgj, propanolol (20 to 480 mg), timolol (5 to 20 mg) 50 mg) and methyldopa (65 to 2000 mg) In addition, there are mixtures with three drugs such as hydrochlorothiazide (15 to 200 mgj plus amiloride (5 to 20 mg) + converting enzyme inhibitor of the invention (3 to 200 mgj or hydrochlorothiazide (15 to 200 mg)). up to 200 mg) + timolol (5 to 50 mg) + converting enzyme inhibitor according to the invention (3 to 200 mg), an effective mixture for the treatment of hypertension in hypertensive patients. distribution of daily allowance.

The dosage varies depending on the severity of the disease, the weight of the patient, and other factors assessed by the physician. The above compositions are formulated into pharmaceutical formulations as set forth 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 it will achieve appropriate dosages within a given range.

Examples of adjuvants that may be incorporated into ^; tablets, capsules and the like are: a binder such as gum 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 stearate magnesium, a sweetener such as sucrose, lactose or saccharin, a flavoring agent such as peppermint essential oil, oil of wintergreen 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 sweetening agent, methyl and propylparaben as a preservative, a colorant, 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. Buffers, preservatives, antioxidants and the like can be incorporated as desired.

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

Example 1

A. N- (1-Carboxy-3-phenylpropyl) -L-lysyl-L-proline (hydrochloride salt)

A solution of 2-oxo-4-phenylbutyric acid and ε-t-BOC-L-lysyl-L-proline in water was adjusted to pH 7 with sodium hydroxide and treated with sodium cyanoborohydride at room temperature for several days. Essentially the entire ε-t-BOC protecting group is cleaved off when the product adsorbs on a strongly acidic ion exchanger. Crude N- (1-carboxy-3-phenylpropyl) -L-lysyl-L-prolip was eluted from resin with 10% ammonia, lyophilized and purified by gel filtration chromatography (LH-20). The NMR spectrum of the resulting hydrochloride salt of the product agrees with the structure, and the mass spectrum shows a molecular ion at 693 m / e for the tetrasilylated species Chromatography on XAD-2 resin using 3.5 % acetonitrile in 0.1 M ammonium hydroxide gave Na- [1- (S-carboxy-3-phenylpropyl) -L-lysyl-L-proline.

B. N-α- [1- (S-Carboxy-3-phenylpropyl) -L-lysyl-L-proline

A solution of 2-oxo-4-phenylbutyric acid and Ν-ε-tertBoc-L-lysyl-L-proline in water was adjusted to pH 7 with sodium hydroxide and treated with sodium cyanohorohydride at room temperature for several days. The product is adsorbed on a strongly acidic ion exchanger and eluted with 2% pyridine in water. Product-rich fractions were distilled off and treated with 4 N HCl in ethyl acetate to remove the t-Boc protecting group. The resulting hydrochloride salt is converted to the free base by adsorption on a strongly acidic ion exchanger and eluting with 2% pyridine in water. Lyophilization of the product-rich fractions gave N - < - &gt; - (1-carboxy-3-phenylpropyl) -L-lysyl-L-proline as a white fluffy solid. The NMR spectrum was consistent with the structure. The mass spectrum shows the molecular ion at 549 for the disilylated species. Chromatography gave the desired isomer.

Example 2

N- (1-methoxycarbonyl-3-methylthiopropyl) -alanyl-L-proline

A solution of pyruvoyl-L-proline (185 mg), L-methionine methyl ester (600 mg), and sodium cyanoborohydride (200 mg) in 20 mL of methanol was made neutral with dilute methanolic sodium hydroxide solution. After; After standing at room temperature for three days, the product is adsorbed on a strongly acidic ion exchanger and eluted with 2% pyridine in water to give 80 mg of the product. The NMR spectrum shows OCH ₃ at 3.95 δ, S - CH ₃ at 2.2 δ and CH - CH ₃ at 1.55 and 1.7 5. The silyl material mass spectrogram shows the expected molecular ion at 404 m / e.

Example 1 a d 3

N- [1-Methoxycarbonyl-2- (3-indolyl) ethyl] -alanyl-L-proline

In the same manner as in Example 2, tryptophan methyl ester was condensed with pyruvoyl-L-proline in the presence of sodium cyanoborohydride to give N- (1-methoxy-12-carbonyl-2- (3-indolyl) ethyl) -alanyl-L-proline.

NMR spectrum in CDCl _i shows aromatic protons at 6.9 to 7.7, protons adjacent to the aromatic nucleus and adjacent to nitrogen at 2.8 to 3.9; aliphatic methylene protons at 1.4-2.7 and alaninomethyl at 1.0-1.4. The mass spectrogram of the silyl material shows an ion at 516 m / e consistent with a dlsilylated material having a loss of the CH _{: J} group.

Example 4

N- [1 (S) -methoxycarbonyl-2- (1H-imidazol-5-ylethyl) -DL-alanyl-L-proline

The method described in Example 2 condenses L-histidine methyl ester with pyruvoyl-L-proline in the presence of sodium cyanoborohydride to give N- [1-methoxycarbonyl-2- (1H-imidazol-4-yl) ethyl] -DL-alanyl-L -proline. The NMR spectrum in D _2.0 shows imidazole protons at 8.6 and 7.3; imidazole adjacent protons and methyl ester protons at 3.7 and alanylmethyl at 1.1-1.38.

Example 5

N- [1 (S) -ethoxycarbonyl-5-aminopentyl] -D, L-alanyl-L-proline

A solution of ε-benzoyloxycarbonyl-L-lysine-ethyl ester hydrochloride (2.94 g) in water (10 mL) was basified with 15 mL of saturated aqueous potassium bicarbonate solution and extracted with CH ₂ Cl ₂ .

The extract was dried with magnesium sulfate and concentrated to dryness. The residue, ε-benzyloxycarbonyl-L-lysine-ethyl ester, was dissolved in tetrahydrofuran (20 ml) and pyruvoylproline (555 mg) and powdered molecular sieve No. 4A (1.0 g) were added. The mixture was stirred at room temperature for 4 hours. 630 mg of sodium cyanoborohydride in 1 ml of CH ₃ OH was added over two hours and the mixture was stirred overnight. It was then filtered, concentrated to dryness and the residue partitioned between 10 mL of water and 15 mL of CH ₂ Cl ₂ (15 mL).

The aqueous phase is adsorbed on a strongly acidic ion exchanger and eluted with 4% pyridine in water to give 470 mg of N- [1 (S) -ethoxycarbonyl-5-benzyl oxycarbonylaminopentyl] -D, L-alanyl-L-proline . The protecting group is removed by hydrogenation in a 1: 1 mixture of ethanol and water to 10% palladium on carbon catalyst at 39 psig. The mixture was filtered and the filtrate was evaporated to dryness. The residue in methanol is chromatographed on a LH-20 column to give the desired N- [1 (S) -ethoxycarbonyl-5-amino-pentyl] -D, L-alanyl-L-proline. The NMR spectrum (D ₂ O) and the mass spectrum of the following trimethylsilylation confirm the structure.

The mass spectrum of the silylated 2H7u material gives a peak at 559 m / e for the trisilylated derivative and a peak at 487 m / e for the disilylated derivative.

Example 6

N- [1-carboxy-2- (S) -amino-3-phenylpropyl] -D, L-alanyl-h-proline

2-Amino-4-phenyl-3- (S) -3-phthaloylaminobutanoic acid is condensed with pyruvoyl-L-proline using sodium cyanoborohydride in methanol in a neutral medium to give N- (1-carboxy-3-phenyl- 2-phthaloylamino-D, L-alanyl-L-proline as a mixture of isomers.

This material was refluxed in ethanol with one equivalent of hydrazine for 1.5 hours, cooled, the phthalhydrazide was filtered off and the desired product isolated by chromatographic methods to give the title compound.

Thin layer chromatography of silica gel with 10 EtoAc: 5 pyridine: 1 HOAc:

: 3 H ₂ O gives a spot with R _f = 0.15.

Example 7

N * [1-carboxy-2- (S-benzoylamino-3-phenylpropyl) -D, L-alanyl-L-proline

A solution of N-phthaloyl-3-amino-4-phenyl-2-hydroxybutyronitrile in ethanol saturated with aqueous ammonia was allowed to stand at room temperature for 3 days. The solvent * was removed in vacuo and the residue was refluxed in concentrated hydrochloric acid for 6 hours. Evaporate to dryness and purify the residue on a Dowex® 50 (H ⁺ ) ion exchange column, eluting sequentially with water-methanol 10: 1, water-pyridine 50: 1 and finally with 0.5 M ammonium hydroxide solution. The desired 2,3-diamino-4-phenylpropionic acid is isolated from this last eluent by concentration to dryness. A solution of the copper complex of this amino acid is prepared and benzoylated in situ with benzoyl chloride under basic conditions using the method described by R, Roeske et al., J. Am. Chem. Soc., 78, 5883 (1956). The copper complex is cleaved with hydrogen sulfide to give 2-amino-3- (S-benzoylamino-4-phenylbutyric acid) This intermediate is condensed with pyruvoyl-2-proline using sodium cyanoborohydride in methanol. in neutral medium to give the desired N- [1-carboxy-2- (S-benzoylamino-3-phenylpropyl) -D, L-alanyl-L-prolm as a mixture of isomers, which may be separated, if appropriate, by chromatographic methods.

The mass spectrum shows a peak at 596 m / e for the dislylylated molecular ion minus 15. The NMR spectrum shows the absorbance for two phenyls at 7.0-7.5 δ and diastereomeric methyls at 1.1 δ.

Claims (1)

A process for the preparation of carboxyalkyldipeptides of the formula I OR, R _{: {} R &lt; ₄ &gt; -rf Ί; ^;; f · ιι ii. ·.? Rc = C-NH-CH-C-N-C-C-R _(; R ₂ O · 'R- where' R 1 and R 2 _(i) are the same or different and are hydroxy, C 1 -C 6 alkoxy, C 1 -C 6 alkenoxy, C 1 -C 6 dialkylaminoalkoxy, C 1 -C 6 acylaminoalkoxy 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 aryl atoms of the aryl radical, substituted aryloxy group of at least 6 carbon atoms or substituted aralkoxy of 1 to 3 carbon atoms in the alkyl radical and at least 6 carbon atoms in the aryl radical, wherein the substituent is methyl, halogen or a methoxy, amino, C1-4alkylamino group (C 1 -C 6) dialkylamino, (C 1 -C 4) -alkylamino; hunting the residue and at least 6 carbon atoms in the aryl residue or a hydroxyamirio 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, imidazolyl, 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 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, aralkenyl of 1 to 3 4 carbon atoms in the alkenyl radical 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, C1-C3 alkyl, hydroxy, C1-C3 alkoxy, amino, amlnomethyl, C2-C12 acylamino, C1-C4 dialkylamino C 3 -C 3 alkyl, 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 5 and R 2 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 to 6 carbon atoms, hydroxyalkyl of 1 to 6 carbon atoms, acetylaminoalkyl of 1 up to 6 carbon atoms, acylaminoalkyl of 1 to 6 carbon atoms in the alkyl radical and 2 to 12 carbon atoms in the acyl radical, aminoalkyl of 1 to 6 carbon atoms, dimethylaminoalkyl of 1 to 6 carbon atoms, haloalkyl of 1 to 6 carbon atoms, guanidinoalkyl (C 1 -C 6), (C 1 -C 6) imidazolylalkyl, (C 1 -C 6) indolylalkyl, (C 1 -C 6) mercaptoalkyl and (C 1 -C 6) alkylthioalkyl, R ₄ is hydrogen or alkyl of 1 to 6 carbon atoms, R 5 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 C 1 -C 8 imidazolylalkyl; 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, R ₄ and R 5 are optionally joined together to form an alkylene bridge of 2 to 4 carbon atoms, C 2 -C 3 alkylene bridge, C 1 -C 4 alkylene bridge or C 2 -C 4 alkylene bridge substituted by hydroxy, C 1 -C 6 alkoxy or C 1 -C 6 alkyl Or a pharmaceutically acceptable salt or biologically active isomer thereof, characterized in that an amine of formula II is reacted. OR ₄ II I. R — C — c — nh ₂ (II) ^R 2 wherein R 1 is as defined above, and may include appropriate protection of any reactive group, and R and R ₂ are as defined above, with a ketone of formula III R ₃ OR ₄ R 5 O = C — C — N — C — CO — Rg (III) I 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, then optionally protecting groups to give a compound of formula I wherein R and R 8 are as defined above, except for the hydroxy group and R _b R ₂ , R ₃ , R ₄ , R ₅ and R ₇ are as defined above and optionally converted by R and / or R g by hydrolysis or hydrogenation of a suitable intermediate to the hydroxy group and optionally forming a salt thereof and optionally isolating the more biologically active isomer by chromatography or fractional crystallization.