Process for preparing carboxyalkylacylaminoacids

The present invention relates to a process for the preparation of novel carboxyalkylacylamino acids and related compounds which are derivatives of proline, picolic acid, azetidine-2-carboxylic acid and having the general formula 1:

Rs

R4 R1 H2C- (CH) n

IIII

R - OC— (CH)₁₁—CH — CO — N — CH-COR (1), where is

R is hydroxy, -amino or (C 1 -C 4) alkoxy,

R 1 and R 4 are each a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms or a phenylalkyl group having from 1 to 4 carbon atoms in the alkyl moiety,

R 2 is hydroxy, amino, hydroxyamino or (C 1 -C 4) alkoxy,

R3 is hydrogen, hydroxy or (C1-C4) alkyl, m 1, 2 or 3,

η. 0, 1 or 2.

Asterisks indicate asymmetric carbon atoms. The carbon atoms in the acyclic chain are asymmetric. when R 1 or R 4 is other than hydrogen.

The present invention includes proline derivatives, pipecolic acid, azetidine-2-carboxylic acid, and related compounds of Formula 1. In this large group of compounds, some subgroups of compounds are more preferred for their properties than other subgroups of compounds.

Preferred are the compounds of formula (1) in which - R is hydrogen or lower alkoxy, in particular hydroxy, R1 is hydrogen or lower alkyl, R2 is hydroxy, R5 and R4 are each hydrogen, m is 2 and n or 1 or Preferably, R4 is on the adjacent carbon atom

4 with a carbonyl-terminal acid group are derived from proline and have generic design groups. rec 2,

Particularly preferred are compounds which

R4 'Ri / \

R2-OC- (CH) n'-CH-CO-N where is

R 'is hydroxy or (C 1 -C 4) -alkoxy,

R1, R2 is as defined for formula (1),

R4^Ť a hydrogen atom or a (C 1 -C 4) alkyl group, in particular a methyl group and the number 1 or 2.

Of the compounds of formula (2), the subgroups in the series a) to n) are always preferred, and in this series their preference gradually increases over the compounds representing a particularly preferred embodiment:

a) R is hydroxy,

b) n represents 1;

c) n represents 2,

d) R 2 represents hydroxy, ................

e) R2 is hydroxyamino;

f) R2 is -alkoxy, g is R4 is methyl,

h) R4 represents a hydrogen atom,

i) R 1 represents a hydrogen atom_tor methyl,

j) R is hydroxy, R 1 is hydrogen or methyl,

k) R 1 and R 2 are each hydroxy, R 1 and R 4 are each hydrogen or methyl and n is 1 or 2;

l) R and R2 are each hydroxy-

COR '(2), nu, R 1 and R 4 represent each hydrogen atom and n is 2,

m) R 1 and R 2 represent. each hydroxy, R 1 is methyl, R 4 is hydrogen and n is 1,

п) R 1 and R 2 are each hydroxy, R 1 is methyl, R 4 is hydrogen and n is 2. '

Stereoisomers in which proline is in the L-form are particularly preferred.

Alkyl groups referred to in the various symbols are straight or branched chain alkyl groups from methyl to butyl, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, i.e. butyl and the like. Alkoxy groups of the same type having 1 to 4 carbon atoms attached to an oxygen atom, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, i.e. butoxy, and the like. Of the alkyl groups and alkoxy groups, -C 1 -C 2 groups are particularly preferred. A preferred phenylalkyl group is phenylmethyl.

In general, the compounds of the invention are prepared by acylating a compound of formula 3,

Ro

AND

HzC— (CH)_ni

II

HN-CH-COR (3) wherein R 1 -R 3 and m are as defined above, with an acid of formula 4,

R4Ri .li

R 2 = OC- (CH) n-CH-COOH

(4) wherein R 1, R 2, R 4 and n are as defined above, or an equivalent thereof.

In a preferred embodiment, the acid of formula 3a is reacted,

R3

AND

H2C- (CH) m

HN-CH-OOH (3a) wherein R 3 represents a hydrogen atom, a hydroxy group or an alkyl group, and is as defined above, for example proline, hydroxyproline, 4-methylproline, pipecolic acid, 5-hydrcoxypipecolic acid, azetidine-2-carboxylic acid or similarly to the monoester of malonic acid, succinic acid, gluitaric acid, etc. of formula 4a,

About Rd Ri

X - O - C - (C H J 11 - CH - COOH, (4a) wherein X represents a lower alkyl group,

R 1, R d are as defined above, in any known manner in which the acid of formula 4a is activated prior to reaction with the acid of formula 3a, including forming a mixed anhydride, symmetrical anhydride, acid chloride, active ester, Woedward reagent K N, N'-carbonylbisimidazole, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline and the like. (For an overview of these methods, see Methoden der organischen Chemie - Methods of Organic Chemistry - Houben-Weyl, Volume XV, Part 1 and 2, 1974 ..)

The product of this reaction is a compound of formula 5,

Rs

AND

O R4 Ri HaC - (CH),_n

X - O - C - (CH) n - CH - CO - N - CH - COOH ', (5) where ^!R1, R3, R4, X and π are as defined above, which are saponified, for example, with a base such as sodium hydroxide as is known per se. by a process to obtain the free diacid of formula 6,

Rs

AND

R4 R1 HaC- (CH) m

HOOC— (CH)_n—CH — CO — N — CH — COOH, (6) wherein R 1, R 5, R 4 and n are as defined above.

Conversely, the free acid can be esterified in a manner known per se.

In a varied process, an acid ester of formula 3a, for example a lower alkyl ester, can be used to react with the monoester of formula 4a to give a compound of formula 7,

R3

AND

O R4 Ri H2C— (CH)_m r₅C (CH), - CH - CO - N - CH - COR (7) wherein R and R 5 are ester groups, for example alkoxy, and R 1, R 3, R 4, m and n are as defined above.

In addition to the above coupling reagents, other reagents such as dicyclohexylcarbodiinide may also be used.

Ammonolysis of the acid of formula 5 gives the amide of formula 8. R3

AND

Rd Ri HaC - (CH) m

II II II

HaN — C— (CH)_n—CH — CO — N — CH — COOH (9)

<td colspan="2">wherein R1, Rs, Rd and n have the above</td><td rowspan="2">of formula 5, a hydroxamic acid of formula 9 is obtained,</td>

<td>or by Hydroxyaminolysis</td><td>acid</td>

<td></td><td></td><td>Rs</td>

<td>O Rd II 1</td><td>lil</td><td>HaC— (CH)_m 1 1</td>

HO — N'H — C— (CH)_n—CH — CO — N — CH — COOH, (9) wherein R 1, R 5, R d, m and n are as defined above.

The monoester starting material 4a, where n is zero, is obtained from the corresponding malonic acid diester as described in Organic Syntheses 37, 34 (1957) .A succinic acid monoesters of formula 4a (wherein, for example, n is equal to 1) is prepared by alcoholysis corresponding to substituted succinic anhydride It is preferred to prepare products in which the ester group is in the β-position to the alkyl group of the side chain.

Preferably, alkylidene succinic anhydride is used to obtain the requisite reglospecificity in alkofholysis. for the preparation of the starting monoester, for example the anhydride of formula 10,

<img file="CS197285B2_D0001.tif" />

(10) where it represents

R 'is hydrogen, alkyl or phenyl;

R 'is hydrogen or alkyl.

Compound. of formula 10 is treated with an alcohol of formula

ROH, wherein R is as defined above to give the product of formula (11),

R '

I COOH

<img file="CS197285B2_D0002.tif" />

\

COOR (11) wherein R, R and R 'are as defined above, which reduction with hydrogen yields a compound of Formula 12,

Ri COOH

<img file="CS197285B2_D0003.tif" />

COOR wherein R and R 1 are as defined above.

Similarly, in the case of glutaric acids (e.g., n is 2) alkylidene derivatives are used. If such alkylidene derivatives are not readily available, the substituted glutaric anhydride is subjected to alcoholysis and the mono-ester is then carefully purified by traction crystallization of the dicyclohexylammonium salt.

Compounds of formula 1 have one asymmetric carbon atom and two when R 1 or R 4 are different from hydrogen. These carbon atoms are marked with an asterisk in formula 1. The compounds are therefore in diastereoisomeric form or in the form of racemic mixtures. All of these compounds fall under the general formula 1. The racemate or one of the enantiomers may be used as starting materials in the process according to the invention. If racemic starting materials are used, the stereoisomers obtained can be separated by conventional chromatography or by fractional crystallization. Generally Features (! 2)

L-isomer with respect to the carbon atom of the amino acid is the preferred isomeric form.

Compounds prepared by the method of. of the invention form basic salts. with various inorganic or organic bases; these salts are also included in the invention. Such salts include ammonium salts, alkali metal salts such as sodium and potassium, those are preferred, alkaline earth metal salts such as calcium and magnesium salts, organic base salts such as dicyclohexylamine salt, benzathine, N-methyl-D - gucucamine, hydrabamine salt, salts with amino acids such as arginine,. lysine and the like; non-toxic, physiologically acceptable salts are preferred, although other salts are also useful, for example, in the isolation or purification of the product, as exemplified by the examples of the dicyclohexylamine salt.

The salts are prepared in a conventional manner by reacting the free acid product with one or more equivalents of a suitable base to give the desired cation in a solvent or environment in which the salt is insoluble. or¹ in water and removal of water by freeze-drying. Treatment of the salt with an insoluble acid such as a cation exchange resin in a hydrogen form (for example a polystyrene sulfonic acid resin such as Dowex 50) or an aqueous acid and extraction with an organic solvent such as ethyl acetate, dichloromethane or the like can yield the free acid and optionally another salt may be prepared.

In the appended examples, examples of particularly preferred embodiments of the process of the invention are described, and the appended examples are also guidelines for preparing other members of the group of compounds of formula (1).

The compounds of formula I prepared by the process of the invention inhibit the conversion of decapeptiidangiotensin I to angiotensin II and are therefore useful for reducing or eliminating angiotensin-induced hypertension. The action of the -renin enzyme on -angiotensinogen, pseudoglobulin - in blood plasma, results in angiotensin I. Angiotensin I is converted by angiotensin converting enzyme (ACE) to angiotensin II. Angiotensin II is a blood pressure booster that is thought to be the cause of various forms of hypertension in pink mammal species, such as rats and dogs. The compounds prepared by the method of the invention participate in the sequence of renin angiotensin I-angiotensin II by inhibiting the angiotensin-converting enzyme and reducing or eliminating the formation of anglotensin II increasing blood pressure.

Thus, administration of a composition comprising a single compound of Formula 1 or a combination of a compound of Formula 1, or a physiologically acceptable salt thereof, removes angiotensin-induced hypertension in a mammal suffering therefrom. One dose or preferably two to four divided daily doses of about 1 to 1000 mg / kg per day, preferably 10 to 100 mg / kg per day, is suitable for lowering blood pressure, as shown in animal experiments described by SL Engl , TR Schaeffer, Μ. H. Waugh and B. Ruby in Why. Soc. - Exp. Biol. Copper. 143, 483 (197-3). The agent is preferably administered orally, but a parenteral route, such as the subcutaneous, intramuscular, intravenous or intraperitoneal route may also be used.

Compounds of formula 1 wherein R is other than hydroxy and R 2 is amino or alkoxy are converted in the body to two carboxy groups.

The compounds prepared by the method of the invention may be used to lower blood pressure when processed into tablets, capsules or elixirs for oral administration or sterile solutions or suspensions for parenteral administration. - Around. . 10 - to - -509- mg of a compound of formula I or a mixture of - - compounds of formula 1 or a physiologically acceptable salt thereof is treated with physiologically acceptable binders, carriers, excipients, stabilizers, preservatives and fragrances, etc. to unit doses which are suitable for pharmaceutical practice. The amount of active ingredient in such formulations and formulations is such that a suitable dosage will be obtained for the indicated use.

Adjuvants which may be used for tablets, capsules and the like include: binders such as gum tragacanth, acacia, corn starch or gelatin; excipients such as dicalcium phosphate; disintegrants such as cereal starch, potato starch, alginic acid and the like; lubricants such as magnesium stearate; sweetening agents such as sucrose, lactose or saccharide; fragrant substances, such as peppermint, oil of wintergreen, or dusk.

If the dosage form is a capsule, it may contain liquid carriers such as fatty oils in addition to the above-mentioned substances.

Various other substances may also be used, such as¹ are coatings or other physical-modifying unit dosage forms. For example, tab¹ethyls may be coated with shellac, - with sugar or with both shellac and sugar. A syrup or elixir may contain an active compound, a sucrose, a sweetener, methylparaben, and propylparaben as a preservative, a colorant, and a flavoring agent, such as a dim or orange essence.

Sterile injectables may be formulated according to known pharmaceutical practice, such as dissolving or suspending the active ingredient in a binder such as water for injection, natural oils such as sesame oil, coconut oil, peanut oil, cottonseed oil, etc., or as synthetic fatty binders, such as ethyl oleate or the like. If desired, buffers, preservatives, antioxidants and the like can be added.

The process according to the invention is illustrated by the accompanying examples, which describe particularly preferred embodiments of the invention. Temperatures are meant in ° C.

Example 1

L-proline tert-butyl ester

L-proline (230 g) was dissolved in a mixture of water (1 liter) and 5N sodium hydroxide solution (400 ml). The solution was cooled rapidly in an ice bath and 5N sodium hydroxide solution (460 ml) and benzyloxycarbonyl chloride (340 ml) were added with vigorous stirring in five equal portions over a half hour. After stirring at room temperature for 1 hour, the mixture was extracted twice with ether and acidified with concentrated hydrochloric acid. The precipitate is. feniltru197285 is and · dried. 442 g of product are obtained, m.p. 78-80 ° C.

The benzyloxycarbonyl-L-proline thus obtained (180 g) was dissolved in a mixture of dichloromethane (300 ml), liquid isobutylene (800 ml) and concentrated sulfuric acid (7.2 ml), and the solution was then shaken in a pressurized bottle. The pressure was released, the isobutylene was allowed to evaporate and the solution was washed with 5% sodium carbonate solution, water, dried (MgSO4) and evaporated to dryness in vacuo to give benzyloxycarbonyl-L-proline tert-butyl ester. quantity 205 g.

Benzyloxycarbonyl-L-proline tert -butyl ester (205 g) is dissolved in absolute ethanol (1.2 · 1) and hydrogenated under normal pressure with 10% palladium on carbon (10 g) so that it is dissolved in the (24 hours), the catalyst is filtered off and the filtrate is evaporated in a vacuum of 100 mm Hg, and the residue is distilled in vacuo to give L-proline tert-butyl ester and boiling point / 0.13 Hg. Mp 50-51 ° C.

Example 1 and 2

1- (2-Ethoxycarbonylpropanoyl) -L-proline tert-butyl ester

Monoethyl methyl malonate [prepared as described in Organic Syntheses - · Organic Syntheses - 37, 34 (1957)] (2.92 · g) and tert-butyl L-proline ester (3.42 g) was dissolved in dichloromethane (80 mL) . The solution was cooled rapidly with stirring in an ice bath. Dicyclohexylcarbodiimide (4.12 g) was added and the mixture was stirred for 15 minutes in an ice bath and for 16 hours at room temperature. The precipitate was filtered off and the filtrate was evaporated to dryness in vacuo. The residue was dissolved in ethyl acetate and washed with 5% aqueous potassium sulfate solution, water, saturated sodium bicarbonate solution and water. The organic phase was dried (MgSO4) and evaporated to dryness in vacuo to give 1- (4-ethoxycarbonylpropanoyl) -L-proline tert-butyl ester (5.9 g).

Example 3

1- (2-ethoxycarbonylpropanoyl) -L-proline

The ester obtained according to the method of Example 2 (5.9 g) was dissolved in trifluoroacetic acid, the solution was left at room temperature for one hour and then evaporated to dryness in vacuo. The residue was dissolved in a mixture of ethyl acetate and saturated aqueous sodium bicarbonate. The aqueous phase was acidified and extracted with ethyl acetate. The ethyl acetate layer was dried over magnesium sulfate and evaporated to dryness in vacuo to give 1- (2-ethoxycarbonylpropipanoyl) -L-proline in 4.1 g.

He attaches

1- [2-carbo^ιxypropanoyl] -L-proline

1- (2-ethoxycarbonylpropanoyl) -L-proline (4.1 g) was dissolved in a mixture of 1 N sodium hydroxide solution (51 ml) and methanol (51 ml). The mixture was stirred at room temperature for six hours and then evaporated to half volume in vacuo, ion-exchange resin (Bowex 50) (50 ml) was added and the suspension was applied to a column of 150 ml of the same resin. Fractions containing the desired material (positive for the carboxyl reagent) were collected and freeze-dried to give 1- (2-carboxypropanoyl) -L-proline in a yield of 1.5 g.

Example 5

1- (2-carbamoylpropanoyl) -L-proline

1- (2-ethoxycarbonylpropanoyl) -L-proline (2.0 g) was dissolved in 10% methanolic ammonia and the mixture was left at room temperature in a pressurized bottle. When thin layer chromatography analysis indicated that all of the starting material had been converted to an amide, the mixture was evaporated to dryness and the remaining ammonium salt was converted to the free acid with an ion exchange resin (Dowex 50 in hydrogen form) to give 1- ( 2-carbamoylpropanoyl) -L- in a yield of 1.1 g.

Example · 6

1- (2-hydroxycarbamoylpropanoyl) -L-proline as 1- (2-ethoxycarbamoyl) -propanoyl) -L-proline sodium salt (2.4 · g) was dissolved in absolute ethanol (8 ml). An ethanolic solution of hydroxylamine (prepared from hydroxylamine hydrochloride [0.7 g] and sodium ethylate) was added, followed by a solution of sodium (0.23 g) in absolute ethanol (8 ml). of ether (500 mL). The precipitate was filtered off and dried to give 1- (2-hydroxycarbamoylpropanoyl) -L-proline sodium salt in a yield of 2 g. The free acid was prepared by ionic treatment (Dowex 50 in hydrogen form).

Example 7

1- (2-Ethoxycarbonyl-3-phenyl-propanoyl) -L-proline tert-butyl ester

Replacement of monoethyl m-ethyl malonate with monoethylbenzyl malonate (prepared according to the method of R. Fralse-Julleen and C. Frejaville, Bull. Soc. Chem. France, 219, 1970) in the method of Example 2 gives tert-butyl 1- (2-ethoxycarboinyl) ester. -3-phenylpropanoyl) -L-proline.

Example 8

1- (2-ethoxy, carbonyl-3-phenylpropanoyl) -L-proline

Using 1- (2-ethoxycarbonyl-3-phenylpropanoyl-L-proline tert -butyl ester in the method of Example 3) gave 1- (2-ethoxycarbonyl-3-phenylpropanoyl) -L-proline.

Example 9.

1- (2-Carboxy-3-phenylpropanopyridyl) bblproline

Treatment of 1- (2-ethoxycarb (anyl-3-phenylpropanoyl) -L-proline as described in Example 4 affords 1- (2-carboxy-3d).^?enylpropanoyl) -L-proline.

Example 10

1- (2-carbamoyl-3-phenylpropanoyl) -L-proline

Treatment of 1- (2-methoxycarbonyl-3-phenylpropanoyl) -L-proline as in Example 5 affords 1- (2-carbamoyl-3-phenylpropanoyl) -L-proline.

Example 11

1- (2-Hydroxycarbamoyl-3-phenylpropanoyl) -L-proline sodium salt

Treatment of 1- (2-ethoxycarbonyl-3-phenylproranoyl) -L-rroline as described in Example 6 provides 1- (2-hydroxycarbamoyl-3-phenylpropanoyl) -L-proline sodium salt. .

Example 12

1- (3-Methoxycarbonyl-2-methylpropanoyl) -L-proline tert-butyl ester

3-Methoxycarbonyl-2-methylenepropanoic acid (36 g) was dissolved in absolute ethanol (400 mL) and hydrogenated in the presence of 10% palladium on carbon (3.6 g) until no more hydrogen was absorbed. The catalyst is filtered off and the filtrate is evaporated to dryness in vacuo. The residue (37 g) and L-proline tert-butyl ester (42.7 g) were dissolved in methylene chloride (750 mL) and the solution was cooled rapidly with stirring in an ice bath. Dicyclohexylcarbodiimide (51.5 g) was added and the mixture was stirred at room temperature for 18 hours. The precipitate was filtered off and the filtrate was evaporated to dryness in vacuo. The residue was dissolved in ethyl acetate and washed until neutral. The ethyl acetate was dried over magnesium sulfate and evaporated to dryness in vacuo. The residue was dissolved in ether and the acylurea by-product was collected by filtration. The filtrate was evaporated to dryness in vacuo to give 1- (3-methoxycarbonyl-24-methyl} propanoyl) -Lq) roline tert-butyl ester in a yield of 64.7 g.

Example 13

1- (3-methoxycarbonyl-2-methylpropanoyl) -L-proline

1- (3-N-methoxycarbonyl-2-methylrropanoyl) -L-propyl tert -butyl ester is dissolved in trifluoroacetic acid (150 ml) and the solution is left at room temperature for one hour. The trifluoroacetic acid is removed (mostly by evaporation) to dryness It is precipitated several times from ether-hexane (yield 18.3 g).

The product was dissolved in acetonitrile (10 mL) and d-cyclohexylamine was added. The crystals were collected by filtration, suspended in acetonitrile (590 mL), boiled for five minutes, cooled, filtered and dried. These crystals were resuspended in acetonitrile (450 mL) and boiled for five minutes, cooled, filtered and dried to give 13.6 g of product. mp 193-194 ° C; the product is dicyclohexylamine salt of 1- (4-methoxycarbonyl-2-D-methylpropanoyl) -L-proline. 6.2 g of dicyclohexylamine salt of 1- (3-methoxycarbonyl-2-L-methylpropanoyl) -L-proline having a melting point of 138-139 [deg.] C. are obtained from the first acetonitrile mother liquor. These salts are converted to 1- (3-methoxycarbonyl-2-methylrropanoyl) -L-rroline by ion exchange treatment (Dowex 50).

Example 14

1- (3-Carbonyloxy-2-aminoethylpropan-1-ol) -L-proline

Each of the dicyclohexylammonium salts obtained according to Example 13 (19.5 g) was dissolved in a mixture of methanol (137 ml) and 1N sodium hydroxide solution (137 ml) and the solution was stirred at room temperature for five hours. The free diacid is isolated by chromatography on a Dowex 50 ion exchanger. [and)_D²⁵ M.p. = -70.5 (c 2, ethanol). N- (3-carboxy-2-L-methylpropanoyl-L-proline) has a melting point of 132-133 ° C;²⁵ -66.8 ° (c 1.1, ethanol).

Example 15

1- (3-carboxymethyl-2-ethyl-propanoyl) -L-proline.

Treatment of 1- (3-methoxycarbonyl-2-methylpropanoyl-4-proline) as described in Example 5 affords 11 (3-carbamoyl-2-methylpropylpentyl) -L-proline.

Example 16

1- (3-hydroxycarbamoyl-2-methylpropanoyl) -L-proline

Treatment of 1- (3-methylcarbonyl-2-methylpropanoyl) -L-proline as described in Example 6 affords 1- (3-hydroxycarbamoyl-2-methylpropanoyl) -L-proline.

Ex - - 1 ad 17

1- (3-Methoxycarbonyl-1- (3-methoxybenzyl) -p-1-yl] -L-proline tert-butyl ester)

a] 3-Methoxycarbonyl-2-benzylidenepropanoic acid

2-Carboxymethyl-3-phenylpropenoic acid (4.1 g) and acetic anhydride (9 ml) were heated on a steam bath for 70 minutes, evaporated to dryness and the residue triturated with ether to yield 3.6 g. Dissolve in 7 ml of methanol and heat in a steam bath for one hour.

b]

Following the procedure described in Example 12, substituting 3-methoxycarbonyl-2-benzyldepropanoic acid for 3-methoxycarbonyl-2-melthylenepropanoic acid, 1- (3-methoxycarbonyl-2-benzypropanoyl) -1-L-proline tert-butyl ester was obtained.

Example 18

1- (3-Methoxycarbonyl-2-benzylpropanoyl) -L-proline

Treatment of 1- (3-methoxycarbonyl-2-benzylpropanoyl) -L-proline tert-butyl ester as described in Example 13 affords 1- (3-methoxycarbonyl-2-benzzolidinoyl) -L-proline.

Example 19, 1- (3-carboxy-2-benzzopropanoyl) -L-prolie

Treatment of the 1- (3-methoxycarbonyl- 2-benzzpropyeoyl) -L-proline as described in Example 14 affords 1- (3-carboxy-2-benzylpropanoyl) -L-proline.

Example 20

1- (3-carbamozl-2-benzylpropano-1) -L-proline

Treatment of 1- [3-methoxycarbonyl-2-benzepropanoyl] -L-proline as described in Example 5 affords 1- (3-carbamoyl-4-carboxylic acid). iropanoyl] -L-proline.

Example 21

1- (3-Hydroxycarbamyl-2-benzylpropanoyl) -L-proline

Treatment of 1- (3-methoxycarbonyl-2-beezylpropylthioyl) -L-proline as described in Example 6 affords 1- (3-hydroxycarbamoyl-2-benzylpropanoyl) -L-proline.

Example 22

1- (4-carboxybutanoyl) -L-proline

Anhzdrid^F1 glutaric acid (4.6 g) and L-proline; (4.6 g) are suspended in anhydrous pyridine (40 ml) and refluxed for one hour, the mixture is evaporated to dryness in vacuo and the residue is dissolved in water and placed on water. Dowex 50 [75 mL] column and eluted with water to collect the fractions containing the desired material (positive for carboxyl reagent) and evaporate to dryness. The residue was dissolved in acetonitrile (50 mL) and di-cyclohexylamine was added until the pH was alkaline (wet indicator paper) .The crystals were filtered, dried and recrystallized from isopropanol (55 mL) to give the dicyclohexylamine salt 1- (4-carboxzbutaeoyl) -L-prolieu - (14 ° C - mp 170-172 ° C).

The dicyclohexylamine salt is converted back to acid with Dowex 50 in water.

Example 23

1- (4-Methoxycarbonyl-2-methylbutanoyl) -L-proline tert-butyl ester α] 4-methoxycarbonyl-2-methylbutyric acid

2-Methylglutaric acid (14.6 g) and acetonitrile ^j(26 ml) was heated in a steam bath for one hour, the mixture was evaporated to dryness in vacuo and the residue evaporated twice from -toluene, dissolved in methanol (4.7 ml), heated on a steam bath. The residue was dissolved in a mixture of ether (17 ml), dicyclohexylamine - (16.7 ml) and hexane (83 ml), and the crystalline salt was filtered off, stirred and treated with boiling ethyl acetate ( 75 ml]. The insoluble matter is filtered off and the filtrate is concentrated to one third of its volume and quenched. The crystals were filtered off and dried, yielding 11.3 g of 4-methoxycarbonyl-2-methylbutanoic acid as dicyclohexylamine salt, m.p. 97-99.^CC. The salt is converted to the free acid by treatment with Dowex 50.

b] Methoxycarbonyl-2-methylbutanoic acid (3.1 g) and L-proline tert-butyl ester (3.78 g) were dissolved in dichloromethane (40 ml) and the solution was cooled rapidly with stirring in an ice bath and added. Dicyclohexylcarbodiirniide (4.12 g) was stirred for 15 minutes in an ice bath and then for 18 hours at room temperature, the precipitate was filtered off and the filtrate was evaporated to dryness in vacuo. The residue was chromatographed on a silica gel column with chloroform to give 1- (4-methoxycarbonyl-2-methylbutanoyl) -L-proline tert-butyl ester in 3.5 g.

Example 24

1- (4-methoxycarbonyl-2-methylbutanoyl) -L-proline

1- (4-Me. Tert-butyl ester)^andthoxycarbonyl-2-methylbutanoyl) -L-polin (3.4 g) was dissolved in trifluoroacetic acid (2.5 ml) and the solution was left at room temperature for one hour. The trifluoroacetic acid was removed in vacuo and the residue was precipitated The residue was dissolved in acetone / tril (12 mL) and 2 mL of dicyclohexylamine was added. The crystalline salt was isolated by filtration and recrystallization from acetonitrile to give 1.8 g of 1- (4-methoxycarbonyl-2-D-methylbutanoyl) -L-proline dicyrlohexylammonium salt, m.p. 174-175 ° C. also separates in the form of the dicyclohexylamine salt of 1- (4-methoxy)^ιcarbonyl-2-L-methyl-butanoyl] -L-proline isomer. The salt is converted to the acid by treatment with Dowex 50.

Example 25 · (4-Carboxy-2-methylbutanoyl) -L-proline

Each of the long-cyclohexylamoyl salt obtained as described in Example 24 (1.3 g) was dissolved in methanol (9 ml) and N sodium hydroxide solution (9 ml). After five hours, the acid is isolated by ion exchange chromatography on Dowex 50, yield 0.8 g. When sc uses the 1- (4-methoxyoxyboyyl-2-D-methylbutanoyl) -L-proline isomer according to Example 24, the 1- (4-carboxyl-2-carboxylic acid) and after crystallization from acetonitrile has a melting point of 154-156.^CC, yield 594 mg.

i6a]₀25 99 (c 1.3, ethyl alcohol).

Using the same procedure, but using 1- (4-methoxycarbonyl) -2-L-methylbutanoyl) -L-proline (750 mg), gave 1- (4carbioxy-2-L-me).^lthylbutanoyl) -L-prolm (397 mg, mp 156-157 ° C).

1(0-)0²⁵ - 22.5 (c 1.5, ethanol) after crystallization from acetonitrile.

Example 26 '

1- (4-Carbamoyl-2-methylbutanoyl) -L-proline

Treatment of 1- (4-methoxycarbonyl) -2-methylbutanoyl) -L-proline as described in Example 5 affords 1- (4-carbamoyl-2-methylbutanoyl) -L-proline.

Example 27

1- (4-hydroxycarbamoyl-2-methylbutanoyl) -L-proline

Treatment of 1- (4-methoxycarbonyl-2-methylbutanoyl) -L-proline as described in Example 6 affords 1- (4-hydroxycarbamoyl-2-methylbutanoyl) -L-proline.

Example 1 · 28

1- (4-Methoxycarbonyl-2-benzyl) butanoyl-L-proline tert-butyl ester

Treatment of benzylglutaric acid (CA 75, 48 378e) as described in Example 23 affords 1- (4-methoxybutyl-2-butylbutayoyl) -L-proline tert-butyl ester.

EXAMPLE 29 1- (4-Methoxycarbonyl-2-benzylbutanoyl) -L-proline

Treatment of 1- (4-methoxycarbonyl-2-benzylbutanoyl) -L-proline tert-butyl ester as described in Example 24 affords 1- (4-methoxycarbonyl-2-benzylbutanoyl) -L-proline.

Example 30

1- (4-carboxy-2-benzylbutanoyl) -4- (4-carboxylic acid)

Treatment of 1- (4-methoxycarbonyl-2-benzymutancyl) -L-proline by the method. as described in Example 25 gave 1- (4-carboxy-2-benzylbutanoyl) -L-proline.

EXAMPLE 31 · (4-rarbamoyl-2-beylzylbutyl)] -L-pгolin

Treatment of 1- (4-methoxycarbonyl-2-benzylbutanoyl-L-proline) as described in Example 5 affords 1- (4-carbamoyl-2-benzylbutanoyl) -L-proline.

EXAMPLE 32 1- (4-Hydroxycarbamoyl-2-benzylbutanoyl) -L-proline

Treatment of 1- (4-methoxycarbonyl-2-benzylbutanoyl) -L-proline as described in Example 6 affords 1d1-hydroxycarbamoyl-2-benzylbutanoyl) -L-proline.

Example 33

1- (2-ethoxycarbonylpropanoyl) -L-hydroxyproline

Monoethyl methyl malonate (1.46 g) and N-hydroxysuccinimide (1.15 g) were dissolved in ethyl acetate and the solution was cooled rapidly with stirring in an ice-bath. Dicyclohexylcarbodiimide (2.06 g) was added and the mixture was stirred for 15 minutes in an ice bath and over ncc at room temperature. The precipitate is filtered off and the filtrate is evaporated to dryness. The residue was dissolved in pyridine - (15 ml) and added to a mixture of L-4-hydroxyproline (3.30 g), sodium bicarbonate (2.5 g) and water (15 ml). Stir for 18 hours at room temperature, then add water (60 mL) and extract with ethyl acetate. The aqueous phase is acidified (to pH 2) and extracted with ethyl acetate. The ethyl acetate layer was dried over magnesium sulfate and evaporated to dryness to give 1- (2-ethoxycarbonylpropanoyl) -L-hydroxyproline.

Example 34

1- (2-carboxypropanoyl) -L-hydroxyproline

1- (2-Ethoxycarbonylpropanoyl) -L-hydroxyproline was dissolved in a mixture of methanol (20 ml) and 1N sodium hydroxide solution (20 ml). After six hours, the solvent was removed in vacuo to half volume and loaded onto a Dowex 50 ion exchange column (50 mL) and eluted with water to give 1- (2-carboxypropanoyl) -L-hydroxyproline.

Example 35

1- (2-carboxypropanoyl) -L-azetidine-2-carboxylic acid

Using L-azctidine-2-carboxylic acid instead of L-hydroxyproline in the method described in Example 33 and then proceeding as described in Example 34 gives 1- (2-ethoxycarbonylpropanoyl) -L-azetidine-2-carboxylic acid and optionally 1- (2-carboxypropanoyl) -L-azetidine-4-carboxylic acid.

Example 36

1- (2-Carboxypropanil) -L-pipecolic acid

Using L-pipecolic acid instead of β-β-β-imino-proline in the method described in Example 33 and then proceeding as described in Example 34, 1-ct-methoxycarbonylpropanoyl) -L-pipecolic acid is obtained at and optionally Ί1 (2-carboxypeptanpanan) -L-pipecolic acid.

Example 37

Using 3-methoxycarbonyl-2-methyl) propanoic acid in place of monoethyl methyl malonate in the method described in Example 34 affords 1- (B-methoxycarbonyl-4-methylpropanoyl) -L-hydroxypropyl and 1- (3-carboxy-2-methylpropanoyl) -L- hydroxyproline.

Example 38

1- (3-carboxy-2-methylpropanoyl) -1-azideidine-2-carbonyl acid

Using 3-methoxycarbonyl) 2-methylpropanoic acid instead of monoethyl methyl malonate and -L-azetidine-4-carboxylic acid instead of hydroxypropyl in the method described in Example 33, - and then proceeding as described in Example 33. . Example 34 yields 1- (3-methylcarbonyl-2-methylpropylcyl) -1) azetidin-2-carboxylic acid and optionally 1- (3-carboxy-2-methylpropanoyl) -L-azetidine -2-Carboxylic acid.

Example 1 -d - 39

1- (3-carboxy-2-methylpropanoyl) -L-piperic acid

Using 3-methoxycarbonyl-2-methylpropanoic acid instead of monoethyl methyl malonate and L-pipecolic acid instead of hydroxyproline in the method of Example 33 and following the procedure of Example 34 yields 1- (4-methoxycarbonyl-4-methylproppanoyl) -L-pipecolic acid and optionally 1- (3-Carboxy-2-methylpropanoyl) -L-piperecic acid.

Example 1 - d 40

1- (4-Carbonyloxy-2-methylbutancyl) -L-4-carboxylic acid proline

Using 4-methoxycarbonyl-2-methylbutanoic acid in place of monoethyl methyl malonate in the method of Example 33 and then proceeding as described in Example 34, 1- (4-methoxycarbonylphenyl) -2-methylbutancyl) -L-hydroxyproline is obtained. optionally 1- (4-carboxy-2-methylbutanoyl) -L-hydroxyproline.

EXAMPLE 41 1- (4-Carboxy-2-methylbutanoyl) -1-azetidine-2-carboxylic acid

Using 4-methoxycarbonyl-2-methylbutanoic acid in place of monoethyl methyl malonate and L-azetidine-2-carbonyl acid in place of hydroxyproline in the method described in Example 33, and then following the procedure described in Example 34, 1- (4-methoxycarbones 1-2) is obtained. (methylbutanoyl) -L-azetidine-2-carboxylic acid and optionally b- [4'-carboxylic acid (2-methyl-butanoyl) -1H-azetidine-2-carboxylic acid.

Example 42

1- [4-carboxy-2-methylbutanoyl] -L-pipecolic acid

Using 4- (4-methoxycarbonyl-2-methylbutanoic acid instead of monoethyl methyl malonate and L-pipecolic acid instead of hydroxypropine), 1- (4-methoxycarbonyl-2-methylbutanoyl) -1-pipecic acid was obtained as described in Example 33 and then as described in Example 34. and optionally 1- (4-carboxy-2-methyl-11-amino) -L-pipecolic acid.

Example 43:

b- (3-carboxypropanoyl) -L-proline

Succinic anhydride (67 mmol,

6.7 g are dissolved in 100 ml of hot glacial acetic acid and cooled to room temperature. To this solution was added (67 mmol, 7.7 g) of L-proline with stirring. It was left at room temperature for 20 hours and the reaction mixture was evaporated in vacuo. The residue was extracted three times with hot ethyl acetate and cooled to room temperature. Dicyclohexylamine is added to the combined b- (3-carboxypropanoyl) -L-proline extracts and the crystals are recrystallized from hot isopropariol; yield 11.3 g. The dicyclohexylamine salt has a melting point (170) of 175-177 ° C.

Example 44

1- (3-L-carboxybutanoyl) -L-proline

Itaconic anhydride (154 mmol) was dissolved in glacial acetic acid (103 ml), cooled rapidly in an ice bath and stirred. L-Proline (17.7 g) dissolved in 110 ml of glacial acetic acid was added to the mixture. After five minutes, the ice bath was removed and the reaction mixture was left at room temperature for three days. The crude reaction mixture was taken up in one liter of acetonitrile and the insoluble matter was filtered off. The filtrate was evaporated to dryness under vacuum. About 26 g of the residue, 1- (3-carboxy-3-methylenepropanoyl) -L-proline, is recrystallized from water; the yield is 15.3 g, the melting point (82) is 84-85 ° C, after drying for four hours at 50 ° C the melting point is 125-127 ° C.

1- (3-carboxy-3-piperidin-1-yl) -L-proline (3 g) was dissolved in 50 ml of 95% ethanol and 300 mg of 20% palladium on carbon was added.

The suspension is stirred under positive hydrogen pressure for 18 hours. The catalyst was filtered off (Hyflo) and the filtrate evaporated in vacuo to dryness. The crude product is taken up in water and lyophilized, the lyopholate (DL) (3 g) is taken up in 15 ml of acetonitrile and two equivalents of dicyclohexylamine are added. The spray crystalline product was recrystallized from 60 ml of isopropanol, yield 3.17 g, mp (183) 187-189 ° C.

1- (β-L-catboxybutanoyl) -L-proline dicyclohexylamine salt (3 g) is treated with Dowex 50 ion exchange resin in water to isolate free 1- (3-L-carboxybutanoyl) -L-proline which is lyophilized and the lyophilate was recrystallized from acetonitrile-ether. Yield 691 mg, m.p. (122) 124-125 ° C.

Example 45 • (3-D-Carboxybutanoyl) -L-proline

The mother liquor from the crystallization of the dicyclohexylamine salt of Example 44 (isopropanol) is evaporated to dryness and recrystallized from acetonitrile; yield 3.2 g, mp (155) 160-165 ° C. Dissolve the salt (3 g) in 15 ml of water and add 15 ml of Dowex 50 ion exchange resin to adjust the pH below 7. A column of the same ion-exchange resin washed with water is added to a 20 ml column. The product is eluted with water and the fractions which are positive for the carboxyl reagent are lyophilized. The yield was 1.08 g of 1- (3-D-carboxybutanoyl) -L-proline.

Example 46

1- (3-carboxy-bunzylbropanoyl) -L-4-valine

Benzylidene succinic anhydride (1.88 g) was suspended in 20 ml of anhydrous pyridine. Add L-proline (1.15 g) in steam for two and a half hours. Immediately the color darkens. After cooling to room temperature, the insoluble precipitate was filtered off (m.p. 232-233 ° C) and the filtrate was evaporated to dryness in vacuo. The residue was extracted with ether and the ether was decanted off. The residue was taken up in ethyl acetate and washed with 5% potassium sulfate solution and water. The ethyl acetate extracts were filtered and evaporated to dryness in vacuo. The crude product, 1- (3-carboxy-3-uylazyl) -L-proline, was triturated with ether and after 48 hours 2.0 g of product were obtained, m.p. 132-135.^QC.

The crude material (1.9 g) was taken up in 30 ml of 95% ethanol and 200 mg of 10% palladium on carbon was added. Stir under positive hydrogen pressure for 18 hours. The reaction mixture was filtered through Hyflo and the filtrate was evaporated to dryness in vacuo, yield 1.9 g. The product was purified on a diethylaminoethyl Sefadex column with acid ammonium carbonate. 1.4 g are obtained. The ammonium salt was converted to 1- (3-carboxy-3-Uenzylpropanoyl) -L-proline free acid by loading onto a Dowex 50 ion exchange column with aqueous methanol (8: 2). Yield 1.3 g. Load on column ♦

Silica gel (70-230 mesh) in chloroform (60), methanol (40) and 38% acetic acid (20), eluted with the same system and lyophilized. Yield 1.1 g.

Example 47

1- (4-carboxy-3-methylbutanoyl) -L-proline (isomer A)

3-Methyglutaric anhydride (1.28 g) and L-proline tert-butyl ester (1.88 g) were stirred in 5 ml dry tetrahydrofuran in an ice bath for 5 minutes. The bath was removed and the reaction continued at room temperature for three hours. A crystalline precipitate is formed immediately. Ether (10 mL) was added and the crystals were filtered off, yield. mp 168-170 ° C.

The 1- (4-carboxy-3-methylpropanoyl) -L-proline tert-butyl ester thus prepared is dissolved in 10 ml of trifluoroacetic acid and left for one hour at room temperature, evaporated to dryness and taken up in water. and lyophilized. The lyophilisate is taken up in 10 ml of water and added to 55 ml of Dowex 50 ion exchange resin and eluted with water. Carboxylic reagent-positive fractions that do not give the color typical of trifluoroacetic acid are collected and lyophilized. The yield was 1.03 g of 1- (4-carboxy-3-methylbutanoyl) -L-proline. The dicyclohexylamine salt prepared by the method of Example 22 has a melting point of 170-172 ° C.

Example 48

1- (4-carboxy-3-methylbutanoyl) -L-proline (isomer B)

3-Methylglutaric anhydride (1.28 g) and Lproline tert-butyl ester (1.88 g) in 5 ml dry tetrahydrofuran were stirred in an ice bath for 5 minutes. The bath is removed. After 3 hours 10 ml of ether are added. The crystalline precipitate of 1- (4-carboxy-3-methylbutanoyl) -L-proline (isomer A) is filtered off and the filtrate is evaporated to dryness in vacuo. The dicyclohexylamine salt is prepared in isoproylether 1.4 g (m.p. 97-98 ° C). This salt is converted to the free acid by partitioning between ethyl acetate and 5% potassium sulphate solution, yield 922 mg.

The ester is taken up in 10 ml of trifluoroacetic acid and left at room temperature for one hour. It is then evaporated to dryness under vacuum, taken up in water and lyophilized. The lyophilate is taken up in 10 ml of water and added to 54 ml of Dowex 50 resin and eluted with water. The carboxylic reagent positive fractions, which do not give the typical color for trifluoroacetic acid, are collected and lyophilized to give 1- (4-kaaboxx-3-methylbutanool) -L-proline (isomer B) in a yield of 640 mg. The dicyclohexylamine salt was prepared as described in Example 22, mp 189-191 ° C.

EXAMPLE 49 49- (4-Anrboxy-4-methylbutanobl) -L-rroline

(a) 2-methyl-4-benzyloxycarbonylbutyric acid

2-Methylglutaric acid (14.61 g) was heated in steam for one hour with 26 ml of acetyl chloride, then evaporated to dryness in vacuo and the toluene was removed twice in vacuo. To the crystalline solid was added 12.5 ml of benzyl alcohol and heated for one hour in steam. The crude 2-methyl-4-benzyloxycarbonylbutyric acid in an amount of 26.5 g is loaded onto a silica gel column in chloroform and eluted with chloroform. The dicyclohexblammate salt was prepared as described in Example 22 in a yield of 18 g; mp 84-85 ° C. It was converted to 10.2 g of free acid in ethyl acetate and 5% acidic potassium chloride.

o) 4-Me^ιthi-4-methoxycarbonylbutylic acid

The benzyl ester of (a) (10.2 g) is taken up in 20 ml of methanol and treated with excess ether palzomethanol for one hour at room temperature. Evaporate to dryness in vacuo.

This methyl ester (10.7 g) was dissolved in 150 ml of 95% ethanol and reduced under positive hydrogen pressure in the presence of 1 g of 10% palladium on carbon for 18 hours. Filtered through Hyflo, the filtrate was evaporated to dryness in This gave 6.9 g of 4-methb1-4-methoxycarbonylbutyric acid.

c) 1- (4-carboxy-4-methylbutanoyl) -L-proline

The reduction product of (b) (6.8 g) and tert-butyl L-proline (8.0 g) were dissolved in 85 ml of methbleochloride and stirred in an ice bath. To the mixture was added 8.8 g of dicyclohexylknodilmide. After 15 minutes the bath was removed and the reaction continued overnight at room temperature. The dicyclohexylurea is filtered off and the filtrate is evaporated to dryness in vacuo. 1- (4-Carboxy-4-methyl-butaooyl) -L-roline tert-butyl ester was taken up in ethyl acetate and washed with 5% sodium sulfate solution, water, saturated sodium bicarbonate solution, water, dried over magnesium sulfate. and evaporated to dryness in vacuo, yield 14.0 g.

The tert-butyl ester thus obtained (14.0 g) was treated with 75 ml of trifluoroacetic acid for one hour and evaporated to dryness in vacuo. Evaporation was performed twice with ether-hexane to remove excess trifluoroacetic acid. The crude product is extracted into 150 ml of saturated sodium bicarbonate solution and 250 ml of ethyl acetate. The extracts were washed again with saturated sodium bicarbonate solution. The aqueous fraction was acidified to pH 2 with concentrated hydrochloric acid, saturated with sodium chloride, extracted four times with ethyl acetate, washed once with saturated brine, dried over magnesium sulfate and evaporated to dryness in vacuo. The dicyclohexylamine salt was prepared in ether and recrystallized from ethyl acetate. The yield is

9.3 g, melting point (120) 132 DEG-133 DEG C. This salt is converted to the free acid, to 1- (4-carboxy-3-methylbutanoyl) -L-proline.

The dicyclohexylamine salt (8.7 g) was dissolved in 60 ml of methanol and 60 ml of sodium hydroxide was added with stirring. 100 ml of Dow-ex 50 are added to the mixture to adjust the pH to an acidic reaction. Load onto a 300 ml Dowe.x 50 column and elute with water. Fractions that are positive for the carboxyl reagent are collected and filtered to give 4.78 g of b- (4-carboxy-4-methylbutanoyl) -L-proline.

EXAMPLE 50 1- (3-Mellioxy-carbonyl-1-2-nmine 1-ro-1-amino) L-prolinamide

1- (3-Methoxycarbonyl-3-methylpropanoyl) -L-proline (2.4 g) was dissolved in a mixture of dichloromethane (50 ml) and triethylamine.

(1.4 mL). The solution was cooled rapidly in an ice-water bath and isobutyl chloroformate (1.36 g) was added while stirring the mixture. After 10 minutes, ammonia (gaseous) was bubbled through the solution for 15 minutes, still in an ice bath. The reaction mixture was stirred for one hour at room temperature, diluted with methylene chloride (100 mL) and washed with water, 0.1 N hydrochloric acid solution, water and dried over magnesium sulfate. The solvent was removed in vacuo to give b- (3-methoxycarbonyl-2-methylrropanoyl) -L-prolinamide.

Example 51

1- (3-arbox у-2 nne 1у 1p i⁴ o, p-n-oyl) -L-proline

1- (3-methoxyxylbenzyl) -2-methylpropanoyl) -L-prolinamide (1.2 g) was dissolved in a mixture of methanol (10 ml) and N sodium hydroxide solution (15 ml) . The mixture was stirred at room temperature and tested by electrophoresis every hour until the starting ester disappeared. The solution was neutralized with normal hydrochloric acid and evaporated in vacuo to half the volume. This solution was loaded onto a Dowex 50 ion exchange resin column and eluted with water. The carboxylic reagent-positive fraction is collected and freeze-dried to give 1- (3-carboxy-2-methylpiperapolin) -L-proline. ·.

Example 52

1- (3-carboxy-3-methyl-propanoyl) -4-methyl-L-proline, Using 3-methoxycarbonyl-2-methylpropanoic acid instead of monoethyl methyl malonate and 4-methyl-L-proline instead of hydroxyproline in the method as described in Example 33 and then continued as described in Example 34 to give 1- (5-methoxycarbonyl-2-methylproranoyl) -4-methyl-L-proline and optionally b- (3-carboxy-2-methylrroranoyl) -4-methyl- L-proline.

Example 53 b- (3-Carboxy-2-methyl-furanoyl) -5-hydroxy-L-pirecolic acid

Using 3-ethoxycarbonyl-2-dimethylpropanoic acid in place of monoethyl methyl malonate and 5-hydroxy-L-pipecolic acid in place of hydroxyproline in the method described in Example 33 and following the procedure described in Example 34 gave 1- (3-methoxycarbonyl-2). methylpropanoyl) -5-hydroyyl-L-pipecolic acid and optionally 1- (3-carboxy-2-methylpropanoyl) -5-hydroxy-L-pipecolic acid.

Example 54.

1- (4-carboxy-2-methylbutanoyl) -4-methyl-L-proline

Using 4-methoxycarbonyl-2-methylbutanoic acid in place of monoethyl methyl malonate and 4-methyl-L-proline instead of hydroxyproline in the method of Example 33. and proceeding as described in Example 34 to give b- (4-methoxycarbonyl-2-methylbutanoyl) -4-methyl-L-proline and optionally 1- (4-carboxy-2-methylbutanoyl) -4-methyl-L-proline .

Example 55

1- (4-carboxy-2-methylbutanoyl) -5-hydroxy-L-pipecolic acid

Using 4-methoxycarbonyl-2-methylbutanoic acid instead of monoethyl methyl malonate and 5-hydroxyidyl-L-pipecolic acid instead of hydroyyrroline in the manner described in Example 33 and following the procedure described in Example 34, 1- (4-methoxycarbonyl-2- methylbutanoyl) -5-hydroxy-L-pipecolic acid and optionally 1- (4-carboxomethoxy-5-hydroxy-L-pipecolic acid).

Example 56

1- (4-Methoxycarbonyl-2-methylbutanoyl) -L-decamide

Using 1- (4-methoxycarbonyl-2-methylbutanoyl) -L-proline according to Example 24 instead of 1- (S-methoxycarbonyl-4-methylpropanoyl) -L-proline in the manner described in Example · 50 gives 1-methyloxycarbonyl-4-methylbutanoyl) -L-prolinamide.

The racemic forms of the end products according to each of the preceding examples are prepared using the DL-form of the starting amino acid instead of the L-form.

Similarly, the final product in the D-form of each of the preceding examples is prepared using the D-form of the starting amino acid instead of the L-form.

Example 57

1000 tablets each containing 100 mg of 1- (4-carboxy-2-methylbutanoyl) -L-proline are prepared from the following ingredients:

1- (4-carboxy-2-methylbutanoyl) -L-proline 100-0g corn starch 50.0g gelatin 7.5g

Avicel (microcrystalline cellulose) 25.0g magnesium stearate 2.5g

1- (4-Carbonyl-2-methylbutanoyl) -L-proline and corn starch are mixed with an aqueous solution of gelatin, dried and comminuted to a fine powder, admixed with Avicel and magnesium stearate and granulated. 1000 tablets, each containing 100 mg of active ingredient, are compressed.

Example 58

1000 tablets, each containing 200 mg of 1- (3-carboxy-2-methylpropanoyl) -L-proline, are prepared from the following ingredients:

1- (3-carboxy-2-II] ethylpropanoyl] -L-proline200 g lactose · · - 100 '· g

Avicel? ; -^; 1550 g corn starch50 g magnesium stearate5 g

The 1- (3-carboxy-2-methylpropanoyl) -proline, lactose and Avicel are mixed and mixed with the corn starch. Magnesium stearate is added. The dry blend is compressed on a tablet press to 10:30 tablets of 505 mg each containing 200 mg of active ingredient. The tabs were coated with a solution of Methocel E-15 (methylcellulose) containing a coloring agent containing yellow as a colorant.

Example 59

Two pieces of gelatin capsules, each containing 250 mg of 1- (4-carboxy-2-methylbutanoyl) -L-proline, are filled with a mixture of the following ingredients:

1- (4-carboxy-2-methylbutanoyl) -L- [beta] -retin 250mg magnesium stearate 7mg

USP lactose 193mg

Example 60

The solution for injection is prepared as follows:

<td>1- (4-carboxybutanoyl) -L-proline</td><td> 5.50</td>

<td>methylp.arabtn</td><td> ' 5</td>

<td>propylparaben</td><td> 1</td>

<td>sodium chloride</td><td> 25</td>

<td>water for injection qs.</td><td> 6</td>

<td>Active ingredients, preservatives</td><td>additives</td>

sodium chloride is dissolved in three liters of water for injection and the volume is adjusted to 5 liters. The solution is filtered through a sterile filter and aseptically filled into pre-sterilized medicaments, which are then sealed with pre-sterilized rubber caps. Each vial contains 5 ml of a solution with a concentration of 100 mg of active ingredient per ml of injection solution.