DK157487B - ANALOGY PROCEDURE FOR THE PREPARATION OF PROLINE DERIVATIVES. - Google Patents

Description

DK 157487B

The present invention relates to an analogous process for the preparation of novel proline derivatives which have been found to be good angiotensin-converting enzyme inhibitors.

The novel proline derivatives have the formula I

R3 R4 R1 Η2ί “^ Η) 2 (I)

2 II

R-S- (gH) n-yH-CO-N gH-COR

wherein R is hydroxy, amino or C 1 -C 7 alkoxy, R 1 and R 4 are each hydrogen, C 1 -C 4 alkyl, phenyl or benzyl, R 2 is hydrogen,

0 M

5 11 5 11 R5-C-, r5_m-c-, r6_s_ egg r7? R 3 is hydrogen, hydroxy or C 1 -C 4 alkyl, R 5 is Οχ-C 7 alkyl, phenyl or phenyl C 1 -C 4 alkyl, R 6 is C 1 -C 7 alkyl or phenyl optionally substituted with halogen, methyl or methoxy, M is 0 or S, n is 0 or 1, R7 is R3 2 (Hg) —CH2 R1 r4 I ii · R-OC-Hg-N-CO-gH- (gH) nS (0) p wherein R, R1, R3, R4 and n have the above meanings, the stars indicating asymmetric carbon atoms. Each of the carbon atoms bearing a substituent R1, R3 and R4 is asymmetric when the substituent is other than hydrogen.

The present invention relates to a process for the preparation of proline and related derivatives of the above Formula I. Within this broad group, certain subgroups are preferred over others because of their properties.

Preferred are such compounds of formula I wherein R is hydroxy or C 1 -C 6 alkoxy, R 1 is hydrogen or alkyl, R 2 is hydrogen, R 5 -CO, R 6 -S- or R 7, R 3 and R 4 are each hydrogen, R is C 1 -C 6 alkyl, especially methyl, or phenyl, R 6 is C 1 -C 6 alkyl, especially methyl or ethyl, n is 0 or 1, especially 1, and in R 7, R, R 3 -, R 3, R 4 and n the same preferred meanings as set forth above.

2

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Particularly preferred are such compounds having the formula R1 (II)

R2-S- (CHO) -CH-CO-N-i-COR

2 n. .

Wherein R is hydroxy or C 1 -C 6 alkoxy, R 1 is hydrogen or C 1 -C 4 alkyl, R 2 is hydrogen, R 5 -CO-, R 6 -S- or R 7, R 5 is C 1 -C 4 alkyl or phenyl, especially the first, R 6 is C 1 -C 6 alkyl and n is 0 or 1.

Within this group of compounds represented by formula II, the following additional preferred subgroups are, in the order a to r of increasing importance, of the compounds which are particularly preferred embodiments: a) R is hydroxy b) n is 1 c) R 2 is hydrogen or C 2 -C 8 alkanoyl d) R 2 is hydrogen e) R 2 is acetyl f) R 1 is hydrogen or C 1 -C 3 alkyl g) R 1 is hydrogen or methyl h) R is hydroxy, R 1 is hydrogen or methyl i) R is hydroxy, R 1 is hydrogen or methyl, R 2 is hydrogen or acetyl and n is 0 or 1 j) R is hydroxy, R 1 and R 2 are each hydrogen and n is 0 k) R is hydroxy, R 1 is hydrogen , R 2 is acetyl and n is 1) R is hydroxy, R 1 is methyl, R 2 is acetyl and n is 1 m) R is hydroxy, R 1 and R 2 are each hydrogen and n is 1 n) R is hydroxy, R 1 is methyl, R 2 is hydrogen, and n is 1 o) R is hydroxy, R 1 is hydrogen, R 2 is C 1 -C 6 alkylthio, and n is 1 r 2 in P) R-OC-I_N-OC-CH (CH 2) n -S-

wherein each R is hydroxy, R 1 is hydrogen or C 1 -C 4 alkyl, especially hydrogen or methyl, and n is 0-1, especially 1 M

2 5 II

q) R 1 is R 5 -M-C- where M is 0 or S.

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It is obvious that combinations of the above, where this is feasible, are among the preferred groups.

The stereoisomers where the proline is in L-form are particularly preferred.

The alkyl groups represented by any of the variables comprise straight and branched chain hydrocarbon groups from methyl to heptyl, e.g. methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl and the like. The alkoxy groups are of the same kind with 1-7 carbon atoms attached to oxygen, e.g. methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy and the like. The C2-C4 groups, especially Cog and C2 groups, of both types are preferred. Phenylmethyl is the preferred phenylalkyl group.

Alkanoyl groups are those having acyl groups of the lower (C 2 -C 7) fatty acids, e.g. acetyl, propionyl, butyryl, isobutyryl and the like. Similarly, the lower alkanoyl groups having up to four carbon atoms and especially acetyl are preferred.

The four common halogens are included in the term "halogen" with chlorine and bromine being preferred. The substituted phenyl groups preferably carry the substituent at the 4-position of the ring. The hydroxyalkyl groups have a hydroxy group on an alkyl chain as described above, preferably on the terminal carbon atom, e.g. hydroxymethyl, 2-hydroxyethyl, etc. The amino (carboxy) alkyl groups have an amino and a carboxy group on an alkyl group as described above, preferably both on one carbon atom, e.g. it terminated as in the preferred 2-amino-2-carboxyethyl group.

The products of formula I and the preferred subgroups can be prepared by various synthetic methods.

The process of the invention for preparing the compounds of formula I is characterized in that:

(a) a compound of formula III

R3 H2C- (CH) 2

I I

HN-CH-COR (III)

wherein R and R 3 have the meanings given above are acylated with an acid of formula IV

4

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R4 R1

2 I I

R 2 -S- (CH) n-CH-COOH (IV) wherein R 1, R 2, R 4 and n have the meanings given above, or a reactive derivative thereof, or b) a compound of formula R 3

Hoc (CH) ->

I I

HN-CH-COR

wherein R and R3 have the meanings given above are acylated with an acid of formula V

R4 R1

I I

X- (CH) n-CH-COOH (V)

wherein R 1, R 4 and n have the meanings given above, X is bromine, chlorine, iodine or tosyloxy, and the resulting product is then subjected to a substitution reaction with the anion of a thiol or thio acid of formula VII

R2-SH (VII) c) a compound of formula R3 H2C- (CH) 2

I I

HN-CH-COR

wherein R and R 3 have the above meanings are acylated with an acid of formula VI

R4 R1

I I

CH = C-COOH (VI) wherein R 1 and R 4 have the meanings given above and that the resulting product is then subjected to an addition reaction with the anion of thiol or thio acid of formula R 2 -SH wherein R 2 has the meaning given above to form of the compound of formula I wherein n is 1 or 5

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d) a compound of formula III

R3 H2C- (CH) 2

I I

NH-CH-COR (III) wherein R and R3 have the above meanings are acylated with a compound of formula R4 R

I I

CHO CH

I I

s-c = o wherein R 1 and R 4 have the meanings given above to form compounds of formula I wherein n is 1 and R 2 is hydrogen, or

e) a compound of formula III

R3 H2C- (CH) 2

I I

NH-CH-COR (III)

wherein R and R3 have the above meanings are acylated with a mercaptoalkanoic acid of formula IX

R4 R1

I I

YS- (CH) n-CH-COOH (IX) wherein R 1, R 4 and n have the meanings given above and Y is R 2 or a protecting group - R 1 R 4 CH 3 °, \ Q 2 ~ CH 2 ~, QJ 'CH 3 CONHCH 2 or R -CH- (CH) n ~ S- which is then removed by conventional methods to form a compound of formula I wherein R 2 is hydrogen and, if desired, ammono lysing a prepared compound of formula I wherein R 2 is R 5 CO-, wherein R5 is as defined above to form a compound of formula I wherein R 2 is hydrogen and, if desired, a prepared compound of formula I wherein R 2 is hydrogen having the halogenated compound 6

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11 5 11 r5-m-c-x wherein R5 and M have the above meanings and X is halogen to form a compound of formula I wherein R2 is

M

5 11 R5-M-C-.

Removal of the protecting group Y may be carried out in a conventional manner such as treatment with hot trifluoroacetic acid, cold trifluoromethanesulfonic acid, mercury acetate, sodium in liquid ammonia, zinc or hydrochloric acid or the like. For an overview of these methods, see "Methoden der Organischen Chemie" (Houben-Weyl), vol. XV, I. Part, page 736 ff. (1974).

When the acid of formula IV is used as an acylating agent, the acylation may occur in the presence of a coupling agent such as dicyclohexyl carbodiimide or the acid may be activated by forming its mixed anhydride, symmetric anhydride, acid chloride, acid ester or use of Woodward reagent K or N-ethoxycarbonyl. -2-ethoxy-l, 2-dihydroquinoline. An overview of these acylation methods is given in "Methoden der Organischen Chemie (Houben.-Weyl), vol. XV / 2, page 1 et seq. (1974).

Compounds of formula III include e.g. proline, hydroxy-proline, 4-methylproline, and their lower alkyl esters. The acylation of such compounds is described in more detail below.

According to a preferred process for the preparation of compounds of formula I, especially where R 2 is R 5 -CO-, an acid or ester of formula III is coupled with a haloalkanoic acid of formula R 4 R

I I

X - (CH) n-CH-COOH (V) where X is halogen, preferably chlorine or bromine. This can be done by one of the known methods in which the acid IV is activated prior to reaction with the acid III, which results in the formation of a mixed anhydride, symmetrical anhydride, acid chloride, active ester or use of Woodward reagent K or EEDQ (N-ethoxycarbonyl-2 ethoxy-l, 2-dihydroxy-droxyquinolin).

The result of this reaction is a compound of formula 7

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R3

4 1 I

R4 R1 H2C- (CH) 2

II II

X- (CH) n-CH-CO-N-CH-COR (X)

This product of formula X is subjected to a rearrangement reaction with the anion of a thioic acid of formula R2-SH (VII) to give a product of formula R3 R4 R1 H2C- (CH) o

, 11 II

R2-S- (CH) n-CH-CO-N-CH-COR (XI) When R2 is R5CO, this product can then be converted to product R3

4 1 I

R4 R1 H2C (CH) 2

II II

HS- (CH) n-CH-CO-N-CH-COR (XII) by ammonolysis. When R2 is a protecting group, the compound of formula XII can then be obtained by removing the protection as described above. When R is an ester group (i.e., R is lower alkoxy), the ester group can be removed, e.g. when R is tert -butoxy or tert-amyloxy, by treating the ester of formula XI or XII with trifluoroacetic acid and anisole to give the corresponding free acid. When other alkoxy groups are present, alkaline hydrolysis will give the corresponding acid.

A variation of this process involves the use of an acrylic acid of formula R4 R1

I I

CH = C-COOH (VI) as starting material. This acrylic acid is first converted to the acid halide form and then reacted with a compound of formula 8

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R3 R4 R1 H2c - (CH) 2 I I I I, λ CH = C-CO-N-CH-COR (XIII) and this intermediate is subjected to the addition reaction with the thiol or thio acid VII as described above.

A tosyloxyalkanoic acid of the formula TJ4 D1 * * (XIV)

CH3 ~ \ 0 / ~ SQ2 ° ~ (CH) n-CH-COOH

may also be used as a means of acylating the acid of formula III, then subjecting the acylation product to the rearrangement reaction, etc. as described above.

The acyl acid of formula VI may also first be reacted with the thio acid of formula VII to produce a product of formula R4 R1 2 1 1 R2-S-CH-CH-C00H (XV) which is converted to its acid halide, e.g. with thionyl chloride, then coupled to the compound of formula III, followed by the same series of steps as described above.

The acid or ester of formula III can also be acylated with a "protected" form of a ω-mercaptoalkanoic acid of formula R4 R

B I I

R8-S- (CH) n-CH-COOH (XVI) where R8 is the "protecting" group. Such "protective" groups may take the form described above.

After the acylation, the protection can be removed from the product by one of the known methods mentioned above.

Yet another acylating agent may be in the form of a thiolactone, e.g. β-propiothiolactone, α-propiothiolactone or α-methyl- / 3-propiothiolactone.

Further details on preferred ways of preparing the compounds are given below and in the particular examples.

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According to a particularly preferred modification, the acid or ester of formula III is acylated with a haloalkanoyl halide of formula R4 R

I I

X - (CH) n-CH-COX (XVII) wherein each X is halogen, preferably chlorine or bromine, R 1 is hydrogen, lower alkyl or phenyl-lower alkyl, and n is 0 or 1. The reaction is carried out in an alkaline medium, eg. dilute alkali metal hydroxide solution, alkali metal bicarbonate or alkali metal carbonate solution at reduced temperature, e.g. ca. 0-15 ° C. The reaction product is subjected to rearrangement with the anion of the thiol or thio acid of formula VII above, also in alkaline medium, preferably alkali metal carbonate solution, and then worked up in the usual manner. The product of this reaction, wherein R 2 in formula I is R 5 -co, is converted to the product wherein R 2 is hydrogen by ammonolysis, e.g. alcoholic ammonia or concentrated ammonium hydroxide solution, or alkaline hydrolysis, e.g. with aqueous metal hydroxide. When an acid of formula III is used as a starting material, the final product obtained as the free carboxylic acid can then be converted to the ester, e.g. by esterification with a diazoalkane such as diazomethane, 1-alkyl-3-p-tolyl triazene such as n-butyl-3-p-tolyl triazene or the like. Treatment of an ester, preferably the methyl ester, with an alcoholic ammonia solution converts the free acid to the amide, i. R is NH 2

According to another variation, an ester, preferably the t-butyl ester, of formula III is treated in an anhydrous medium such as dichloromethane, tetrahydrofuran, dioxane or the like, with a thioalkanonic acid of formula R1 in R2-S- (CH) 2) CH-COOH (XVIII) in the presence of dicyclohexylcarbodiimide, Ν, Ν'-carbonylbisimidazole, ethoxyacetylene, diphenylphosphoryl azide or similar coupling agents at a temperature in the range of ca. 0-10 ° C. The ester group (R) can then be removed, e.g. by treatment with trifluoroacetic acid and anisole at ca. room temperature.

When an ester of formula III wherein R is e.g. is lower alkoxy, especially t-butoxy, acylated with a thiolactone, e.g. Β-propiothiolacone or α-methyl-io-propiothiolactone, the reaction can be carried out for 10 minutes.

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an anhydrous solvent such as tetrahydrofuran, dioxane, methylene chloride or the like at ca. 0 ° C to approx. room temperature. The ester group can be removed with anisole and trifluoroacetic acid as described above.

Similarly, when R2 is

M

5 II R5-M-C-, products of formula I with this substituent are formed by reacting a compound of formula XII with a halogenated compound

M

5 1 R5-H-C-X (XIX) or by reacting a compound of formula X with an alkali metal salt or alkaline earth metal salt of the formula

M

5 in R5-M-C-S-Me (XX) where Me is alkali metal or alkaline earth metal.

The compounds of formula I wherein R 2 is R 6 -S can be prepared by any known method for the synthesis of mixed disulfides, e.g. by reacting a compound of formula XII with a thiosulfinate XXIV, thiosulfonate XXV, sulfenyl halide XXVI, thiosulfate XXVII or sulfenylthiocyanate XXVIII,

0 O

Jl, I

R6-S-S-R6 (XXIV), R6-S-S-R6 (XXV),

II

o R6S-X (XXVI), R6-S-SO3H (XXVII), R6-S-SCN (XXVIII).

In the particular case where R7 is R3

. , I

R4 R1 CH2- (CH) 2

I I I

-S (O) p (CH) n-CH-CO-N-CH-COR

wherein R, R1, R3 and R4 are as indicated for Formula I, the symmetric disulfides can be obtained by direct oxidation of a compound of Formula XII with iodine. Mixed disulfides are obtained by the modification shown in the Examples.

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The compounds of formula I have one or more asymmetric carbon atoms. When R 1, R 3 or R 4 are not hydrogen, the carbon atom to which it is attached is asymmetric. These carbon atoms are indicated by a star of formula I. Accordingly, the compounds occur in stereoisomeric forms or in racemic mixtures thereof.

All of these are within the scope of the invention. The synthesis described above may use the racemate or one of the enantiomers as starting material. When racemic starting material is used in the synthesis, the stereoisomers obtained in the product can be separated by conventional methods of chromatography or fractional crystallization. As a rule, it is the L-isomer with respect to the carbon atoms of the amino acid being the preferred isomeric form. Also, the D-isomer is preferred with respect to the α-carbon atom of the acyl side chain, i.e. the carbon atom bearing R1.

The compounds prepared by the process of the invention form basic salts with various inorganic and organic bases. Such salts include ammonium salts, alkali metal salts such as sodium and potassium salts which are preferred, alkaline earth metal salts such as calcium and magnesium salts, salts with organic bases, e.g. dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, hydrabamine salts, salts with amino acids such as arginine or lysine. The non-toxic, physiologically acceptable salts are preferred.

The salts are commonly formed by reacting the free acid form of the product with one or more equivalents of a suitable base giving the desired cation, in a solvent or medium in which the salt is insoluble, or in water and removing the water by freeze-drying. By neutralizing the salt with an insoluble acid such as a hydrogen cation exchange resin, e.g. polystyrene sulfonic acid resin such as "Dowex 50", or with an aqueous acid and by extraction with an organic solvent, e.g. ethyl acetate, dichloromethane or the like, the free acid form is obtained and, if desired, another salt can be formed.

Further experimental data can be found in the examples relating to the preferred embodiments and also serve as a pattern.

The compounds prepared by the method of the invention inhibit the conversion of the decapeptide angiotension I to 12

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angiotension II and are therefore valuable for reducing or remedying hypertension associated with angiotension. The effect of the enzyme renin on angiotensinogen, a pseudoglobulin in blood plasma, produces angiotensin I. Angiotensin I is converted by the angiotensin converting enzyme (ACE) to angiotensin II. This is an active precursor that has significance as the causative agent of various forms of hypertension in various mammalian species, e.g. rats and dogs. The compounds prepared by the process of the invention interfere with the angiotensin (renin) -> angiotensin I -> angiotensin II sequence by inhibiting angiotensin-converting enzyme and reducing or precluding the formation of the angiotensin II pressor substance. Thus, upon administration of a composition containing one or a combination of compounds of formula I or a physiologically acceptable salt thereof, the hypertension dependent on angiotensin in mammalian species is alleviated. A single dose or preferably 2-4 divided daily doses based on approx. 0.1-100 mg / kg / day, preferably 1-50 mg / kg / day, is appropriate for lowering blood pressure as set forth in the animal experiments described by S.L. Engel, T.R. Schaeffer, M.H. Waugh and B. Rubin in Proc. Soc. Exp.

Biol. With. 143, 483 (1973). The drug is preferably administered orally, but parenteral routes such as subcutaneous, intramuscular intravenously or interperitoneally may be used.

The compounds can be used to achieve a reduction in blood pressure by composition for preparations such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral administration. Ca. 10-500 mg of a compound or mixture of compounds of formula I or a physiologically acceptable salt are mixed with a physiologically acceptable carrier, excipient, binder, preservative, stabilizer, flavoring, etc. to a unit dosage form commonly used in pharmaceutical practice. The amount of active substance in these compositions is such that a suitable dosage is obtained in the range indicated.

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The following examples serve to illustrate the invention and are particularly preferred embodiments.

Example 1 1- (2-Benzoylthioacetyl) -L-proline 5.75 g of L-proline is dissolved in 50 ml of N sodium hydroxide and the solution is cooled in a bath of ice water. 26 ml of 2N sodium hydroxide and 5.65 g of chloroacetyl chloride are added and the mixture is stirred vigorously at room temperature for three hours. A suspension of 7.5 g of thiobenzoic acid and 4.8 g of potassium carbonate in 50 ml of water is added. After stirring for 18 hours at room temperature, the mixture is acidified and extracted with ethyl acetate. The ethyl acetate layer is washed with water, dried over magnesium sulfate and evaporated to dryness in vacuo. The residue weighing 14.6 g is dissolved in 150 ml of ethyl acetate and 11 ml of dicyclohexylamine is added. The crystals are filtered and recrystallized from ethyl acetate to give 5.7 g, mp 151-152 ° C. To convert the salt to the acid, the crystals are dissolved in a mixture of 100 ml of 5% aqueous potassium bisulfate and 300 ml of ethyl acetate. The organic phase is washed once with water, dried with magnesium sulfate and evaporated to dryness in vacuo to give 3.45 g.

Example 2 1- (2-Mercaptoacetyl) -L-proline 3.4 g of 1- (2-benzoylthioacetyl) -L-proline are dissolved in a mixture of 10.5 ml of water and 6.4 ml of concentrated ammonia. After one hour, the reaction mixture is diluted with water and filtered. The filtrate is extracted with ethyl acetate and then acidified with concentrated hydrochloric acid, saturated with sodium chloride and extracted twice with ethyl acetate. The ethyl acetate extracts are washed with saturated sodium chloride and evaporated to dryness to give 1.5 g. The product, 1- (2-mercapto-acetyl) "L-proline is crystallized from ethyl acetate. Melting point 133-135 ° C.

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Example 3 1- (2-Benzoylthioacetyl) -L-proline methyl ester The 1- (2-benzoylthioacetyl) -L-proline prepared in Example 1 is dissolved in methanol and an ethereal solution of diazomethane is added until persistent yellow color. After 15 minutes, a few drops of acetic acid are added and the solvent is removed in vacuo to give the title compound.

Example 4 1- (2-Mercaptoacetyl) -L-prolinamide The product of Example 3 is dissolved in 10% methanolic ammonia and the solution is left to stand in a pressure flask at room temperature.

When thin layer chromatographic analysis shows that the two ester functions have been ammonolized, the reaction mixture is evaporated to dryness to give the title compound.

Example 5 1- (2-Benzoylthioacetyl) -L-hydroxyproline Using L-hydroxyproline in place of the L-proline in the procedure described in Example 1 gives the title compound.

Example 6 1- (2-Mercaptoacetyl) -L-hydroxyproline By treating the product of Example 5 with ammonia as in Example 2, the title compound is obtained.

Example 7 1- (2-Benzoylthiopropanoyl) -L-proline 5.75 g of L-proline is dissolved in 50 ml of aqueous N sodium hydroxide and the solution is cooled in an ice bath with stirring. 25 ml of 2N sodium hydroxide and 8.57 g of 2-bromopropionyl chloride are added in that order and the mixture is removed from the ice bath and stirred at room temperature for one hour. A mixture of 7.5 g of thiobenzoic acid and 4.8 g of potassium carbonate in 50 ml

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15 water is added and the mixture is stirred overnight at room temperature. Acid with concentrated hydrochloric acid, then the aqueous solution is extracted with ethyl acetate and the organic phase is washed with water, dried and evaporated to dryness. The residue, weighing 14.7 g, is chromatographed on a column of 440 g of silica gel with a mixture of benzene and acetic acid (7: 1). The fractions containing the desired material are combined, evaporated to dryness and the residue is precipitated twice with ether / hexane and converted to a dicyclohexylamine salt in ether / hexane, yield 9.4 g, m.p. (142) 148-156 ° C. The dicyclohexylamine salt is converted back to the acid as in Example 1, yield 5.7 g.

Example 8 1- (2-Mercaptopropanoyl) -L-proline 5.7 g of 1- (2-benzoylthiopropanoyl) -L-proline are dissolved in a mixture of 12 ml of water and 9 ml of concentrated ammonium hydroxide with stirring. After one hour, dilute the mixture with 10 ml of water and filter. The filtrate is extracted twice with ethyl acetate, evaporated to one-third of the original volume, acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic phase is washed with saturated sodium chloride, dried and evaporated to dryness in vacuo. The residue, the title compound, is crystallized from ethyl acetate / hexane, yield 3 g, mp (105) 116-120 ° C.

Example 9 1- (3-Benzoylthiopropanoyl) -L-proline 5.75 g of L-proline is dissolved in 50 ml of normal sodium hydroxide and the solution is cooled in an ice bath. 8.5 g of 3-bromopropionyl chloride and 27 ml of 2N sodium hydroxide are added and the mixture is stirred for 10 minutes in an ice bath and three hours at room temperature. A suspension of 7.5 g of thiobenzoic acid and 4.5 g of potassium carbonate in 50 ml of water is added and the mixture is stirred for 18 hours at room temperature. After the mixture is acidified with concentrated hydrochloric acid, the aqueous phase is extracted twice with ethyl acetate. The organic layers are dried over magnesium sulfate and incorporated.

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16 is evaporated to dryness in vacuo to give the title compound in a yield of 7.1 g, mp 101-102 ° C (ethyl acetate / hexane).

Example 10 a) L-proline tert. butyl ester 230 g of L-proline is dissolved in a mixture of 1 liter of water and 400 ml of 5N sodium hydroxide. The solution is cooled in an ice bath and, with vigorous stirring, 460 ml of 5N sodium hydroxide and 340 ml of benzyloxycarbonyl chloride are added in 5 equal portions over half an hour. After stirring for 1 hour at room temperature, the mixture is extracted twice with ether and acidified with concentrated hydrochloric acid. The precipitate is filtered off and dried. Yield 442 g, mp 78-80 ° C.

180 g of the benzyloxycarbonyl-L-proline thus obtained is dissolved in a mixture of 300 ml of dichloromethane, 800 ml of liquid isobutylene and 7.2 ml of concentrated sulfuric acid. The solution is shaken in a pressure flask for 72 hours. The pressure is released, the isobutylene is allowed to evaporate and the solution is washed with 5% sodium carbonate, water, dried over magnesium sulfate and evaporated to dryness in vacuo to give benzyloxycarbonyl-L-pro-tert-butyl ester in a yield of 205 g.

205 g of benzyloxycarbonyl - L-proline tert-butyl ester are dissolved in 1.2 liters of absolute ethanol and hydrogenated at normal pressure with 10 g of 10 palladium on coal until only traces of carbon dioxide can be observed in the outgoing hydrogen gas (24 hours). The catalyst is filtered off and the filtrate is evaporated in vacuo at 30 mm Hg. The residue is distilled in vacuo to give the title compound, boiling point [h [[50-51 ° C].

b) 1- (3-Acetylthiopropanoyl) -L-proline tert-butyl ester 5.13 g of L-proline tert-butyl ester are dissolved in 40 ml of dichloromethane and the solution is cooled in a bath of ice and water. A solution of 6.18 g of dicyclohexylcarbodiimide in 20 ml of dichloromethane is added immediately followed by 4.45 g of 3-acetylthiopropionic acid. After stirring for 15 minutes in the ice-water-hate and filtering for 16 hours at room temperature

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The precipitate is evaporated and the filtrate is evaporated to dryness in vacuo. The residue is dissolved in ethyl acetate and washed neutral. The organic layer is dried over magnesium sulfate and evaporated to dryness in vacuo to give 9.8 g of the title compound.

Example 11 1- (3-Acetylthiopropanoyl) -L-proline 4.7 g of 1- (3-acetylthiopropanoyl) -L-proline tert-butyl ester are dissolved in a mixture of 34 ml of anisole and 68 ml of trifluoroacetic acid and the mixture is kept on room temperature for one hour. The solvents are removed in vacuo and the residue is precipitated from ether / hexane several times. The residue weighing 3.5 g is dissolved in 25 ml of acetonitrile and 2.8 ml of dicyclohexylamine are added. The crystalline salt is filtered and recrystallized from isoprene panol. Yield 3.8 g, mp 176-177 ° C. The salt is genome-converted to 1- (3-acetylthiopropanoyl) -L-proline as in Example 1, yield 1.25 g, mp 89-90 ° C (ethyl acetate / hexane).

Example 12 1- (3-Mercaptopropanoyl) -L-proline tert butyl ester To a solution of 3.42 g of L-proline tert. butyl ester in 10 ml of dry tetrahydrofuran cooled in an ice bath is added 1.76 g of propiothiolactone. After a 5 minute soak in the ice bath and three hours at room temperature, the reaction mixture is diluted with 200 ml of ethyl acetate and washed with 5% potassium bisulfate and water. The organic layer is dried over magnesium sulfate and evaporated to dryness. The residue, the title compound, is crystallized from ether / hexane in 3.6 g yield, mp 57-58 ° C.

Example 13 1- (3-Mercaptopropanoyl) -L-proline Method A 4.9 g of 1- (3-benzoylthiopropanoyl) -L-proline are dissolved in a mixture of 8 ml of water and 5.6 ml of concentrated ammonium hydroxide and the solution is stirred under argon for one hour. The reaction mixture is diluted with water, filtered and the filtrate is extracted with ethyl acetate. The watery fa

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Acidified with concentrated hydrochloric acid, saturated with sodium chloride and extracted with ethyl acetate. The organic layers are washed with saturated sodium chloride, dried over magnesium sulfate and evaporated to dryness in vacuo. The residue, the title compound, is crystallized from ethyl acetate / hexane in a yield of 2.5 g, mp 68-70 ° C.

Method B

Dissolve 0.8 g of 1- (3-acetylthiopropanoyl) -L-proline in 5 ml of 5.5N methanolic ammonia and keep the solution under argon at room temperature. After two hours, the solvent is removed in vacuo, the residue is dissolved in water and placed in an ion exchange column of the H + form. ("Dowex 50" (analytical purity)) and eluted with water. The fractions giving thiol-positive reaction are combined and evaporated to dryness in 0.6 g yield. This product is crystallized from ethyl acetate / hexane as in process A to give the title compound.

Process C

2.3 g of 1- (3-mercaptopropanoyl) -L-proline tert-butyl ester are dissolved in a mixture of 20 ml of anisole and 45 ml of trifluoroacetic acid. After standing for 1 hour at room temperature under argon, the reaction mixture is evaporated to dryness in vacuo and the residue is precipitated several times from ethyl acetate / hexane. The residue, weighing 1.9 g, is dissolved in 30 ml of ethyl acetate and 1.85 ml of dicyclohexylamine is added. The crystalline salt is filtered and recrystallized from isopropanol in a yield of 2 g, mp 187-188 ° C.

This salt is converted to the acid as in Example 1 in a yield of 1.3 g. The product is crystallized from ethyl acetate / hexane as in process A.

salts

Sodium. Dissolve 500 mg of 1- (3-mercaptopropanoyl) -L-proline in a mixture of 2.5 ml of water and 2.5 ml of N sodium hydroxide. The solution is freeze-dried to give the sodium salt.

Magnesium. 500 mg of 1- (3-mercaptopropanoyl) -L-proline, 49.5 mg of magnesium oxide and 10 ml of water are stirred under gentle heating until

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19, complete resolution is obtained. Then, the solvent is removed by freeze-drying to give the magnesium salt.

Calcium. Dissolve 500 mg of 1- (3-mercaptopropanoyl) -2-proline in a mixture of 91 mg of calcium hydroxide and 10 ml of water and freeze-dry the solution to give the calcium salt.

Potassium. Dissolve 500 mg of 1- (3-mercaptopropanoyl) -L-proline in a mixture of 246 mg of potassium bicarbonate and 10 ml of water and freeze-dry to give the potassium salt.

N-methyl-D-glucamine. Dissolve 500 mg of 1- (3-mercaptopropanoyl) -L-proline and 480 mg of N-methyl-D-glucamine in 10 ml of water and freeze-dry to give the N-methyl-D-glucamine salt.

Example 14 1- (3-Mercaptopropanoyl) -L-hydroxyproline

By using L-hydroxyproline in place of the L-proline in the procedure described in Example 7 and then treating the product as given in Method A in Example 13, respectively, 1- (3-benzoylthiopropanoyl) -L-hydroxyproline and 1- (3) are obtained. -mercaptopropanoyl) L - hydroxyproline.

Example 15 1- (3-Mercaptopropanoyl) -4-methyl-L-proline

By using 4-methyl-L-proline instead of the L-proline in Example .9 and then treating the product by the procedure of Example 13, 1- (3-benzoylthiopropanoyl) -4-methyl-L-proline is obtained and 1- (3-mercaptopropanoyl) -4-methyl-L-proline.

Example 16 1- (3-Mercaptopropanoyl) -D-proline

By using D-proline instead of L-proline in the method of Example 9 and then treating the product by the method of Example 13, 1- (3-benzoylthiopropanoyl) -D-proline and 1- (3- mercaptopropanoyl) -D-proline, mp 68-70 ° C.

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Example 17 a) S-Acetylthio-methylpropanoic acid

A mixture of 50 g of thioacetic acid and 40.7 g of methacrylic acid is heated on a steam bath for one hour and then left at room temperature for 18 hours. After being confirmed by NMR spectroscopy that complete reaction of the methacrylic acid is obtained, the reaction mixture is distilled in vacuo and the desired 3-acetylthio-2-methylpropanoic acid is separated in the fraction of boiling point 128.5-131 ° C (2, 6 mm Hg), yield 64 g.

b) 1- (3-Acetylthio-2-methylpropanoyl) -L-proline tert-butyl ester 5.1 g of L-proline t-butyl ester is dissolved in 40 ml of dichloromethane and the solution is stirred and cooled in an ice bath. 6.2 g of dicyclohexylcarbodiimide dissolved in 15 ml of dichloromethane is added immediately followed by a solution of 4.9 g of 3-acetylthio-2-methylpropanoic acid in 5 ml of dichloromethane. After 15 minutes of stirring in an ice bath and 16 hours at room temperature, the precipitate is filtered off and the filtrate is evaporated to dryness in vacuo. The residue is dissolved in ethyl acetate and washed neutral. The organic phase is dried over magnesium sulfate and evaporated to dryness in vacuo. The residue, which is the title compound, is purified by column chromatography (silica gel chloroform), yield 7.9 g.

Example 18 a) 3-Benzoylthio-2-methylpropanoic acid

By using thiobenzoic acid in place of the thioacetic acid in the procedure of Example 17, the title compound is obtained.

b) 1- (3-Benzoylthio-2-methylpropanoyl) -L-proline tert.-butyl ester Using 3-benzoylthio-2-methylpropanoic acid in place of the 3-acetylthio-2-methylpropanoic acid by Example 17 b) method is obtained in the title mentioned in the title.

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Example 19 a) 3-Phenylacetylthio-2-methylpropanoic acid

By using thiophenylacetic acid instead of the thioacetic acid in the process of Example Γ7, the title compound is obtained.

b) 1- (3-Phenylacetylthio-2-methylpropanoyl) -L-proline tert.-butyl ester Using 3-phenylacetylthio-2-methylpropanoic acid in place of the 3-acetylthio-2-methylpropanoic acid by Example 17 b) method is obtained in the title mentioned in the title.

Example 20

1- (3-Acetylthio-2-methylpropanoyl) -L-proline Method A

7.8 g of the 1- (3-acetylthio-2-methyl-propanoyl) -L-proline tert-butyl ester prepared in Example 17 are dissolved in a mixture of 55 ml of anisole and 110 ml of trifluoroacetic acid. After standing for 1 hour at room temperature, the solvent is removed in vacuo and the residue is precipitated several times from ether / hexane. The residue weighing 6.8 g was dissolved in 40 ml of acetonitrile and 4.5 ml of dicyclohexylamine was added. The crystalline salt is boiled with 100 ml of fresh acetonitrile, cooled to room temperature and filtered, yield 3.8 g, mp (165) 187-188 ° C. This material is recrystallized from isopropanol [<x] p -67 ° (C 1.4, EtOH). The crystalline dicyclohexylamine salt is suspended in a mixture of 5% aqueous potassium bisulfate and ethyl acetate.

The organic phase is washed with water and evaporated to dryness. The residue is crystallized from ethyl acetate / hexane to give 1- (3-acetyl-o-thio-2-D-methylpropanoyl-L-proline, m.p. 83-85 C [a] D-162 (c 1.7, EtOH) .

Method B

8.1 g of 3-acetylthio-2-mercaptopropanoic acid and 7 g of thionyl chloride are mixed and the suspension is stirred for 16 hours at room temperature. The reaction mixture is evaporated to dryness and distilled in vacuo (boiling point 80 ° C). These 5.4 g of 3-acetylthio-2-methylpropanoic acid chloride and 15 ml of 2N sodium hydroxide are added to a solution of 3.45 g of L-proline in 30 ml of normal sodium hydroxide cooled in a bath of ice water. After 3

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After stirring at room temperature for 22 hours, the mixture is extracted with ether, the aqueous phase acidified and extracted with ethyl acetate. The organic phase is dried over magnesium sulfate and evaporated to dryness to give 1- (3-acetylthio-2-DL-methylpropanoyl) -L-proline.

Process C

16 g of methacryloyl chloride are added to a solution of 3.45 g of L -., Ι. Η in a mixture of 100 ml of water and 12 g of sodium bicarbonate cooled in a bath of ice water with vigorous stirring. When the addition is complete, the mixture is stirred at room temperature for two hours and then extracted with ether. The aqueous phase is acidified with N hydrochloric acid and extracted with ethyl acetate. The organic phase is evaporated to dryness in vacuo, the residue is mixed with 3.5 g of thiolacetic acid, a few crystals of azobisisobutyronitrile are added and the mixture is heated in a steam bath for two hours. The reaction mixture is dissolved in benzene / acetic acid (75:25) and placed in a column of silica gel. Elution with the same solvent mixture gives 1- (3-acetylthio-2-DL-methylpropanoyl) -L-proline.

Example 21 1- (3-Benzoylthio-2-methylpropanoyl) -L-proline Using 1- (3-benzoylthio-2-methylpropanoyl) -L-proline tert.-butyl ester instead of 1- (3-acetylthio) ) -2-Methylpropanoyl) -1-proline tert-butyl ester in Method A of Example 20 is given the title compound.

Example 22 1- (3-Phenylacetylthio-2-methylpropanoyl) -L-proline Using 1- (3-phenylacetylthio-2-methylpropanoyl) -L-proline tert-butyls instead of 1- (3-acetylthio) (2-Methylpropanoyl) -L-proline tert-butyl ester in Method A of Example 20 is obtained from the title compound.

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Example 23 1- (3-Mercapto-2-D-methylpropanoyl) -L-proline 1- (3-Mercapto-2-methylpropanoyl) -L-proline is obtained by treating the product of each of Examples 20, 21 and 21 as follows. Method: 0.85 g of the thioester is dissolved in 5.5N methanolic ammonia and the solution is kept at room temperature for 2 hours. The solvent is removed in vacuo and the residue is dissolved in water, placed in an ion exchange column of the H + form ("Dowex 50", analytical purity) and eluted with water. The fractions that give positive thiol reaction are pooled and lyophilized. The residue is crystallized from ethyl acetate / hexane, yield 0.3 g. The title compound has a melting point of 103-104 ° C [α] D -131 (C, 2, EtOH).

Example 24 1- (3-Acetylthio-2-methylpropanoyl) -L-proline methyl ester 1- (3-Acetylthio-2-methylpropanoyl) -L-proline is reacted with an ethereal solution of diazomethane according to that of Example 3 described method, thereby obtaining the title mentioned in the title.

Example 25 1- (3-Mercapto-2-methylpropanoyl) -L-prolinamide Using 1- (3-acetylthio-2-methylpropanoyl) -L-proline methyl ester in the process of Example 4 gives the title compound .

Example 26 a) 3-Acetylthio-2-benzylpropanoic acid

By using 2-benzylacrylic acid in place of the methacrylic acid in the process of Example 17, the title compound is obtained.

b) 1- (3-Acetylthio-2-benzylpropanoyl) -L-proline tert-butyl ester

By using 3-acetylthio-2-benzylpropanoic acid in place of the 3-acetylthio-2-methylpropanoic acid in the procedure of Example 15, the title compound is obtained.

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Example 27 1- (3-Acetylthio-2-benzylpropanoyl) -L-proline The product of Example 26 is used instead of the 1- (3-acetylthio-2-methylpropanoyl-L-proline tert-butyl ester in Method A of Example 20, whereby the title mentioned is obtained.

Example 28 1- (3-Mercapto-2-benzylpropanoyl) -L-proline 1- (3-Acetylthio-2-benzylpropanoyl) -L-proline is treated with methanolic ammonia as in Example 23 to give the title compound as an oil, = 0.47 (silica gel, benzene / acetic acid 75:25).

Example 2, Section 1- (3-Mercapto-2-methylpropanoyl) -L-hydroxyproline Using L-hydroxyproline tert-butyl ester tert-butyl ether in the process set forth in Example 17 b), treat the product as in process A in Example 2.0 and then proceed as in Example 23 to obtain respectively 1- (3-acetylthio-2-methylpropanoyl) -L-hydroxyproline - tert.-butyl ester tert.butyl ether, 1- (3-acetylthio-2-methylpropanoyl) - L-hydroxyproline and 1- (3-mercapto-2-methylpropanoyl) -L-hydroxyproline.

Example 30 1- (3-Acetylthiobutanoyl) -L-proline tert.-butyl ester 6.2 g of dicyclohexylcarbodiimide and 4.86 g of 3-acetylthiobutyric acid are added to a solution of 5.1 g of L-proline tert.-butyl ester in 60 ml of dichloromethane while stirring in an ice bath. After 15 minutes, the ice bath is removed and the mixture is stirred at room temperature for 16 hours. The precipitate is filtered, the filtrate is evaporated to dryness and the residue is chromatographed on a silica gel column with chloroform to give the title compound in a yield of 5.2 g.

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Example 31 1- (3-Acetylthiobutanoyl) -L-proline 5.2 g of the 1- (3-acetylthiobutanoyl) -L-proline tert-butyl ester are dissolved in a mixture of 60 ml of trifluoroacetic acid and 30 ml of anisole and the solution is kept at room temperature for one hour. The solvents are removed in vacuo and the residue 1- (3-acetylthiobutanoyl) -L-proline is re-precipitated from ether / hexane several times, yield 4 g. A small aliquot of this material is dissolved in ethyl acetate and dicyclohexylamine is added until is 8-10 (on wet pH paper). The dicyclohexylamine salt immediately crystallizes, mp 175-176 ° C.

Example 32 1- (3-Mercaptobutanoyl) -L-proline 0.86 g of the 1- (3-acetylthiobutanoyl) -L-proline prepared in Example 31 is dissolved in 20 ml of 5.5N methanolic ammonia and the reaction mixture is allowed to stand at room temperature for 2 hours. The solvent is removed in vacuo and the residue is chromatographed on an ion exchange column ("Dowex 50") with water. The fractions containing the title compound are combined and lyophilized, yield 0.6 g. The dicyclohexylamine salt is prepared by the procedure described in Example 31, mp 183-184 ° C.

Example 33 1- [3 - [[(Ethoxy) carbonyl] -thio] -propanoyl] -L-proline 1.2 g of ethyl chloroformate are added to a solution of 2.03 g of 3-mer-captopropanoyl-L-proline for 30 minutes. ml of normal sodium bicarbonate and the mixture is stirred vigorously at 5 ° C for one hour and for two hours at room temperature. After being acidified with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic phase is washed with water, dried with magnesium sulfate and evaporated to dryness to give the title compound.

Example 34 1- [3 - [[(Ethoxy) -thiocarbonyl] -thio] -propanoyl] -L-proline 25 ml of aqueous 2N sodium hydroxide and 8.5 g of 3-bromopropionyl chloride are added to a solution of 5.75 g of L-proline in 50 ml of N sodium hydroxide and

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26 is stirred in an ice bath. After five minutes, the ice bath is removed and stirring is continued at room temperature. After three hours, 9.6 g of ethyl xanthogenic potassium salt is added and the mixture is stirred overnight at room temperature. The solution is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is evaporated to dryness and the residue is chromatographed on a silica gel column with a mixture of benzene and acetic acid (7: 1) as the solvent to give the title compound, mp 94-95 ° C.

Example .35 1- [3 - [[(Benzylthio) carbonyl] thio] propanoyl] -L-proline A solution of 11 ml of benzylthiocarbonyl chloride in 20 ml of dioxane is added in five portions to a solution of 1.6 g of 1- (3-mercaptopropanoyl) -L-proline in 24 ml of normal sodium bicarbonate cooled in an ice bath over 30 minutes. The ice bath is removed and stirring is continued for 2.5 hours at room temperature. After the mixture is acidified with concentrated hydrochloric acid, the aqueous phase is extracted with ethyl acetate. The organic phase is dried over magnesium sulfate and evaporated to dryness to give the title compound.

Example 36 1- [3 - [[(Ethylthio) -thiocarbonyl] -thio] -propanoyl] -L-proline 25 ml of aqueous 2N sodium hydroxide and 8.5 g of 3-bromopropionyl chloride are added to a solution of 5.75 g of L-proline in 50 ml of N sodium hydroxide which is cooled and stirred in an ice bath. After five minutes, the ice bath is removed and stirring is continued at room temperature. After three hours, 10.5 g of ethyl trithiocarbonate potassium salt are added and the mixture is stirred at room temperature overnight. After being acidified with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and evaporated to dryness to give the title compound.

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Example 37 1- [3 - [[(Ethoxy) carbonyl] thio] -2-methylpropanoyl] -L-proline

By using 1- (3-mercapto-2-methylpropanoyl) -L-proline in place of the 3-mercaptopropanoyl-L-proline by the method described in Example 33, the title compound is obtained.

Example 38 1- [3 - [[(Ethoxy) carbonyl] -thio] -butanoyl] -L-proline Using 1- (3-mercaptobutanoyl) -L-proline in place of 3-Elcaptopropanoyl The -L-proline by the procedure described in Example 33 is obtained from the title compound.

Example 39 1- [2 - [[(Benzylthio) carbonyl] thio] propanoyl] -L-proline Using 2-mercaptopropanoyl-L-proline instead of the 3-mer-captopropanoyl-L-proline at the Example 35, the title compound is obtained.

Example 4.0 1- [3 - [[(Ethylthio) -thiocarbonyl] -thio] -propanoyl] -L-proline methyl ester] A solution of 1- [3 - [[(ethylthio) -thiocarbonyl] -thio] -propanoyl] - L-proline in ethyl acetate is treated with an ethereal solution of diazo-methane until a persistent yellow color appears. After removing the yellow color with a few drops of acetic acid, the solvents are removed in vacuo to give the title compound.

Example 41 1- [3 - [[(Phenoxyj-carbonyl] -thio] -propanoyl] -L-proline Using phenylchloroformate instead of ethylchloroformate in the procedure described in Example 33 gives the title compound.

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Example 42 1- [3 - [[(Phenoxy) -carbonyl] -thlo] -butanoyl] -L-proline Using phenyl chloroformate instead of ethyl chloroformate and 4-mercaptobutanoyl-L-proline instead of 3-mercaptopropanoyl-L-proline by the procedure described in Example 33, the title compound is obtained.

Example 43 1- [3- (Ethyldithio) -propanoyl] -L-proline A) 10 g of 3-mercaptopropanoyl-L-proline are added to a solution of 8.4 g of ethyl thiosulfinate in 100 ml of methanol, and the reaction mixture is stirred vigorously at room temperature for 1 hour. four hours. The methanol is removed in vacuo to give the title compound.

B) A solution of 8.4 g of ethyl thiosulfinate in 50 ml of ethanol is added to an aqueous solution of 10 g of 3-mercaptopropanoyl-L-proline maintained at pH 6-7 by careful addition of sodium hydroxide. The mixture is stirred vigorously at room temperature until there is a negative thiol reaction. The mixture is diluted with water, adjusted to pH 8 and extracted with ethyl acetate, the aqueous phase acidified to pH 3 and extracted again with ethyl acetate. This last extract is washed with water, dried and evaporated to dryness to give the title compound.

Example 44 1- [3 - [(4-Methylphenyl) -dithioj-propanoyl] -L-proline A solution of 1.76 g of 4-methylphenylsulphenyl chloride in 20 ml of ether is added to a solution of 2 g of 3-mercaptopropanoyl-L-proline in 20 ml of 0.5N sodium hydroxide cooled in an ice bath. The mixture is stirred vigorously for one hour and the aqueous phase is separated, acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic phase is washed with water, dried and evaporated to dryness to give the title compound.

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Example 45 1- [3- (Phenyldithio) -propanoyl] -L-proline Using phenylthiosulfinate prepared from phenyldisulphide in accordance with U. Weber and P. Hartter, Z. Physiol. Chem., 351, 1384 (1970), instead of the ethylthiosulfinate by the procedure described in Example 43, the title compound is obtained.

Example 46 1- [3 - [(2-Phenylethyl) -dithio] -propanoyl] -L-proline Using 2-phenylethylthiosulfinate, made from phenethyl disulfide, in place of the ethylthiosulfinate described in Example 43, the title mentioned connection.

Example 47 1- [2- (Ethyldithio) -propanoyl] -L-proline Using 2-mercaptopropanoyl-L-proline instead of the 3-mer-captopropanoyl-L-proline by the procedure described in Example 43, the title said connection.

Example 48 1- [3 - [(4-Methylphenyl) -dithio] -butanoyl] -L-proline Using the 3-mercaptobutanoyl-L-proline in place of the 3-mercap-topropanoyl-L-proline at the one described in Example 44 method is obtained in the title mentioned in the title.

Example 49 1- [3- (Ethyldithio) -2-methylpropanoyl] -L-proline methyl ester Using 1- (3-mercapto-2-methylpropanoyl) -L-proline instead of the 3-mercaptopropanoyl-L-proline at the Example 44 and then treating the product with ethereal diazomethane as described in Example 4Ό gives the title compound.

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Example 50 1- [3 - [(4-Methylphenyl) -dithio] -2-methylpropanoyl] -L-hydroxyproline Using 1- (3-mercapto-2-methylpropanoyl) -L-hydroxyproline in place of 3-mercaptopropanoyl The L-proline by the method described in Example 44 is obtained from the title compound.

Example 51.

1- (EDithiobis-t1-propanoyl) -bis-L-proline 0.95 g of 3-mercaptopropanoyl-L-proline is dissolved in 20 ml of water and the pH is adjusted to 6.5 with N sodium hydroxide. An ethanolic solution of iodine is added dropwise, keeping the pH of 6.5 by careful addition of N sodium hydroxide. When a constant yellow color is obtained, the addition of iodine is stopped and the color is removed with a small amount of sodium thiosulfate. The reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic phase is washed with water, dried and evaporated to dryness to give the title compound. The dicyclohexylammonium salt is prepared by adding dicyclohexylamine to a solution of the free acid in acetonitrile, mp 179-180 ° C.

Example 52 1 '- tDithiobis- (2-D-methyl-3-propanoyl) 3-bis-L-proline Using 3-mercapto-2-D-methylpropanoyl-L-proline instead of 3-mercaptopropanoyl-L The proline by the method described in Example 52 is obtained the title compound having a melting point of 236-237 ° C.

Example 53 1,1 '- [Dithiobis- (2-propanoyl) -bis-L-proline Using 2-mercaptopropanoyl-L-proline instead of the 3-mer-captopropanoyl-L-proline by the method described in Example 51 the connection mentioned in the heading is available.

Example 54 1,1 * - (Dithiobisacetyl) -bis-L-hydroxyproline Using 1- (2-mercaptoacetyl) -L-hydroxyproline in place of the 3-mercaptopropanoyl-L-proline the title mentioned in the title.

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Example 55 1,1 '- [Dithiobis- (3-propanoyl)] - bis-4-methafyl-L-proline Using 1- (3-mercaptopropanoyl) -4-methyl-L-proline in place of 3-mercaptopropanoyl The L-proline by the method described in Example 51 is obtained from the title compound.

Example 56 1/1 '- [Dithiobis- (2-benzyl-3-propanoyl)] - hls-L-proline Using 1- (3-merGapto-2-benzylpropanoyl) -L-proline instead of 3-mercaptopropanoyl The L-proline by the method described in Example 51 is obtained from the title compound.

Example 57, 1,1 * - [Dithiobis- (3-butanoyl)] - bis-L-proline Using the 3-mercaptobutanoyl-L-proline instead of the 3-mercaptopropanoyl-L-proline at that of Example 51 · The procedure described is obtained from the compound mentioned in the title.

Example 58 1,11- [Dithiobis (3-propanoyl)] - bis-L-proline methyl ester A solution of 1,1 '- [dithiobis- (3-propanoyl)] - bis-L-proline in methanol is treated with ethereal diazomethane until a constant yellow color is obtained. After 15 minutes, a few drops of acetic acid are added and the solvents removed in vacuo to give the title compound.

Example 59 1,1V- [Dithio- (3-propanoyl)] - bis-L-proline amide A solution of 1,1 '- [dithiobis- (3-propanoyl)] - bis-L-proline methyl ester in methanol is saturated with ammonia during cooling in ice-water bath. The reaction mixture is left at room temperature for 16 hours in a pressure flask and then the solvents are removed in vacuo to give the title compound.

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Example 60 1 / 1'-tDithiobis- (2-phenyl-3-propanoyl) 3-bis-L-proline Using 1- (3-mercapto-2-phenylpropanoyl) -L-proline instead of 3-mercaptopropanoyl The L-proline by the method described in Example 51 is obtained from the title compound.

Example 61 1- [3 - [[3- (2-Carboxy-1-pyrrolidinyl) -3-oxopropyl] -dithio] -2-methylpropanoyl] -L-proline

By using 1,11 - [(sulfinylthio) bis (2-methyl-3-propanoyl)] bis-L-proline in place of the ethylthiosulfinate in the process of Example 43, the title compound is obtained.

Example 62 a) 3-Acetylthio-2-phenylpropanoic acid

By using 2-phenylacrylic acid instead of methacrylic acid in the process described in Example 17 (a), the title compound is obtained.

b) 1- (3-Acetylthio-2-phenylpropanoyl) -L-proline tert-butyl ester

By using 3-acetylthio-2-phenylpropanoic acid in place of the 3-a-cetylthio-2-methylpropanoic acid in the process described in Example 17 (b), the title compound is obtained.

Example 63 1- (3-Mercapto-2-phenylpropanoyl) -L-proline Using 1- (3-acetylthio-2-phenylpropanoyl) -L-proline tert.-butyl ester instead of 1- (3-acetylthio) The 2-methylpropanoyl-L-proline tert-butyl ester by the method described in Example 20 and subjecting the product to ammonolysis as in Example 23 gives the title compound.

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Example 64 a) 3 - [(4-Methoxyphanyl) methylthlo] -2-methylpropanoic acid 15.4 g of p-methoxy-α-toluene thiol (0.1 mole) are added to a solution of 8.6 g of methacrylic acid (0.1 mol) in 50 ml of 2N sodium hydroxide. The mixture is heated on a steam bath for three hours, then refluxed for two hours and cooled. The mixture is extracted with ether, then the aqueous layer is acidified with concentrated HCl and extracted with dichloromethane. The acidic extracts are washed with brine, dried (MgSO4) and evaporated in vacuo. The resulting semi-solid is taken up in 50 ml of dichloromethane, diluted with 50 ml of hexane and cooled. The title compound is collected as a white crystalline solid, mp 74-82 ° C.

b) 1- [3- (4-Methoxyphenyl) methylthio] -2-methylpropanoyl-L-proline-tert-butyl ester 3.6 g of 3 - [(4-methoxyphenyl) methylthio] -2-methylpropanoic acid (0.015 mol ), 2.6 g of L-proline tert-butyl ester (0.015 mol) and 3.1 g of dicyclohexylcarbodiimide (0.015 mol) are dissolved in 50 ml of dichloromethane and stirred for 30 minutes at 0 ° C. The cooling bath is removed and the mixture is stirred overnight (16 hours). The resulting suspension is filtered and the filtrate washed with 5% potassium bisulfate, saturated sodium bicarbonate and brine, then dried (MgSO4) and evaporated in vacuo. The resulting clear oil is placed in a 250 ml silica gel column and chromatographed using 20% ethyl acetate / hexane as eluent. The main fraction (R f = 0.70, silica gel, ethyl acetate) is evaporated to 5.5 g (93%) of 1- [3- (4-methoxyphenyl) methylthio] -2-methylpropanoyl-L-proline tert-butyl ester like a clear oil. = 0.70 (silica gel, ethyl acetate); = 0.60 (silica gel, ether).

c) 1- (3-Mercapto-2-methylpropanoyl) -L-proline 1.2 g of the ester of section a) (0.003 mol), 5 ml of anisole and 0.5 ml of trifluoromethanesulfonic acid are dissolved in 20 ml of trifluoroacetic acid under nitrogen, and the resulting red solution is left at room temperature for one hour. The solution is evaporated in vacuo to a red residue,

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34 which is taken up in ethyl acetate and washed with water, brine, then dried (MgSO4) and evaporated. The residue is repeatedly triturated with hexane and the remaining hexane is evaporated; The oil residue weighs 0.4 g. A portion (180 mg) of this material is subjected to thin-layer preparative chromatography on 2 mm silica gel plates using benzene / acetic acid 75:25 as the eluent. The nitroprusside positive band (R 2 = 0.40) is recovered to give 135 mg of the title compound as an oil. TLC using benzene / acetic acid 75:25 (R f = 0.40) and chloroform / methanol / acetic acid 50:40:10 (R f = 0.62).

Example 65 1- (3-Mercapto-2-D-methylpropanoyl) -L-proline In a blanket of argon, 10.0 g of 1- [3- (acetylthio) -2-D-methylpropanoyl] -L-proline is suspended in 150 ml of water at 10 ° C. To this mixture is added 5N sodium hydroxide and the pH of the solution is maintained at 13 for 1.5 hours. When sodium hydroxide uptake is stopped, the solution is then acidified to pH = 2.0 with concentrated sulfuric acid.

The aqueous solution is then extracted three times with methylene chloride (3 x 150 ml) and the combined methylene chloride fractions are evaporated to an oil. The concentrate is taken up in ethyl acetate, filtered and the filtrate is diluted with 30 ml of hexane. After half an hour, additional hexane is added and then the mixture is cooled to 10 ° C for one hour.

The crystals are filtered and washed with hexane (2 x 25 ml) and dried until the weight is constant to give 6.26 g of the title compound, mp 100-102 ° C.

Example 66 a) 1- [3-Tosyloxy-2-methylpropanoyl] -L-proline

By using 3-tosyloxy-2-methylpropanoic acid chloride in place of the 3-acetylthio-2-methylpropanoic acid chloride in the process described in Example 20B, the title compound is obtained.

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35 b). 1- [3-Acetylthio-2-methylpropanoyl3-L-proline 3.5 g 1- [3-tosyloxy-2-methylpropanoyl] -L-proline is added to a solution of 1.14 g of thiol acetic acid and 3.5 ml of triethylamine in 20 ml of ethyl acetate. The solution is kept at 50 ° C for three hours, cooled, diluted with 100 ml of ethyl acetate and washed with dilute hydrochloric acid. The organic layer is dried and evaporated to dryness in vacuo. The residue is dissolved in acetonitrile and dicyclohexylamine is added. The crystalline precipitate is recrystallized from isopropanol to give 1- [3-acetylthio-2-D-methylpropanoyl) -L-proline dicyclohexylamine salt, m.p. 187-188 ° C, [α] D -67 ° (c 1, 4, EtOH). This salt is converted to the free acid, mp 83-85 ° C (an isomorphic form of mp 104-105 ° C is obtained if the crystallizing solution is inoculated with high melting material).

Example 67 1- (3-Mercaptopropanoyl) -L-proline tert.-butyl ester To a stirred solution of 1.71 g (10 mmol) of proline tert-butyl ester and 1.35 g (10 mmol) of 1- hydroxybenzotriazole hydrate in 20 ml of N, N-dimethylformamide at 0-5 ° C is added 2.06 g (10 mmol) of N, N'-dicyclohexylcarbodiimide. The mixture is stirred for 10 minutes, then 1.06 g (10 mmol) of 3-mercaptopropanoic acid is added in 2 ml of Ν, Ν-dimethylformamide. The mixture is then stirred at 0-5 ° C for one hour and at room temperature overnight.

The precipitated Ν, Ν'-dicyclohexylurea is filtered off and the filtrate is evaporated in vacuo. The residue is taken up in ethyl acetate, washed thoroughly with saturated aqueous sodium bicarbonate, dried and evaporated in vacuo to 2.5 g of oil.

The oil is taken up in ethyl acetate / hexane (1: 1) and placed in a silica gel column of 100 g. Elution with ethyl acetate / hexane (1: 1) gives 1.40 g (54%) of the title compound as a oil that crystallizes on standing. Recrystallization from ether / hexane gives 0.9 g of a colorless crystalline solid, mp 55-60 ° C, identical to the compound of Example 12.

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36

Example 68 1- (3-Mercaptopropanoyl) -L-proline A solution of 75 mg (0.27 mmol) of 1- [3 - [[(ethylamino) carbonyl] thio] propanoyl] -L-proline in 1 1 ml of concentrated ammonium hydroxide and 1 ml of water are left at room temperature for 18 hours under argon. The solution is diluted with a little water and extracted with ether.

The aqueous layer is acidified with cold concentrated hydrochloric acid and extracted with ethyl acetate. The combined extracts are dried and evaporated in vacuo to give a compound identical to the product of Example 13. TLC (silica gel, benzene / acetic acid 7: 3) 0.4.

Example 69 a) Methacryloyl-I-proline 23.0 g (0.2 mole) of L-proline is dissolved in 100 ml of water and stirred in an ice bath. 19.6 ml (0.2 mole) of methacryloyl chloride in 25 ml of methyl isobutyl ketone are added dropwise over three hours. 2N sodium hydroxide solution is added at the same time keeping the reaction mixture pH 7.0. Addition of base is continued for four hours after the addition of acid chloride is complete. The reaction mixture is adjusted to pH 5 with concentrated HCl and extracted with ethyl acetate. The aqueous layer is then acidified to pH 2.5 and carefully extracted with ethyl acetate. The acidic extracts are washed with brine and dried (MgSO4). The ethyl acetate solution is treated with 40 ml of dicyclohexylamine and cooled overnight. The resulting white precipitate is filtered off and dried to give 29 g (39%) of white solid, mp 202-210 ° C. The solid is crystallized from 1.5 liters of acetonitrile / isopropanol (3: 1) to give 19.7 g of methacryloyl-L-proline dicyclohexylamine salt as fine white needles, mp 202-210 ° C.

The salt is dissolved in water / ethyl acetate and the mixture is acidified with concentrated HCl. The resulting suspension is filtered to remove a fine white precipitate which is well washed with ethyl acetate. the filtrate is saturated with sodium chloride and extracted thoroughly with ethyl acetate. The extracts are washed with brine, dried (MgSO 4) and dried

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37 is evaporated to a clear oil which solidifies. Crystallization from ethyl acetate / hexane gives 7.5 g (83%) of the title compound as a white crystalline solid, mp 89-93 ° C. An analytical sample is obtained by recrystallization, mp 95-98 ° C.

b) 1- (3-Acetylthio-2-D-methylpropanoyl) -L-proline 183 mg of methacryloyl-L-proline (0.001 mol) is dissolved in 0.5 ml of thioacetic acid and left at room temperature for 16 hours. in vacuo to a yellow residue. Preparative thin layer chromatography (silica gel, dichloromethane / methanol / acetic acid 90: 5: 5) allows the isolation of 240 mg of a clear oil as the main fraction. TLC (dichloromethane / methanol / acetic acid 90: 5: 5) shows that this material is 1- (3-acetylthio-2-DL-methylpropanoyl) -L-proline corresponding to the product of Example 20 B, = 0.35 ; (benzene / acetic acid 75:25) = 38.

The oil is dissolved in 3 ml of acetonitrile, treated with dicyclohexylamine until the solution is basic and cooled. A white crystalline solid weighing 106 mg, mp 175 * -181 ° C, is collected. Crystallization from isopropanol gives 1- (3-acetylthio-2-D- * methylpropanoyl) -L - proline dicyclohexylamine salt, mp 187-188 ° C, identical to the product of Example 20A.

Example 70 1- [Dithiobis- (2-methyl-3-propanoyl) 3-bis-L-proline Using 3,3'-dithiobis-2-methylpropanoic acid instead of 3-acetylthio-2-methylpropanoic acid at the Example 20, b, the title compound is obtained.

Example 71 1- (3-Mercapto-2-methylpropanoyl) -L-proline 10.0 g of zinc dust is added to a slurry of 5.0 g of the product of Example 159 in 100 ml of 1.0N sulfuric acid and the mixture is stirred at 18 °. C for four hours under a blanket of nitrogen. The solution is then filtered, the zinc is washed with 20 ml of water and the combined filtrates extracted with methylene chloride (3 x 75 ml). The methylene chloride is extracted back with 25 ml of water and then the organic solution is evaporated to an oil. This oil is taken up in 20 ml of ethyl acetate and

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38 is filtered. 15 ml of hexane is added to the filtrate and the mixture is stirred for 15 minutes. Then, another 30 ml of hexane is added and the solution is cooled to 5 ° C for one hour. The mixture is then filtered and the product washed with 2 x 10 ml of hexane and dried to give 4.17 g of white crystals, the title compound. TLC,

Rf = 0.60 (solvent system: benzene / acetic acid 75:25).

Example 72 a) 3-Benzylthio-2-methylpropanoic acid

By using α-toluene thiol instead of p-methoxy-α-toluene thiol in the process described in Example 64 (a), the title compound is obtained.

b) 1- [3- (Benzylthio) -2-methylpropanoyl] -L-proline tert-butyl ester

By using 3-benzylthio-2-methylpropanoic acid in place of the 3 - [(4-methoxyphenyl) methylthio] -2-methylpropanoic acid in the process described in Example 64 (b), the title compound is obtained.

o) 1- [3- (Benzylthio) -2-methylpropanoyl] -L-proline 7.8 g of 1- [3- (benzylthio) -2-methylpropanoyl] -L-proline tert-butyl ester is dissolved in a mixture of 55 ml of anisole and 110 ml of trifluoroacetic acid. After standing at room temperature for 1 hour, the solvent is removed in vacuo and the residue is dissolved in ether, washed several times with saturated sodium chloride, dried over magnesium sulfate and evaporated to dryness in vacuo to give the title compound = 0.5 (silica gel, benzene = acetic acid (3: 1). R f = 0.5 (Silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1).

d) 1- (3-Mercapto-2-methylpropanoyl) -L-proline 0.1 g of 1- [3- (benzylthio) -2-methylpropanoyl (-L-proline) is suspended in 10 ml of boiling liquid ammonia and little is added. pieces of sodium with stirring until the color is constantly blue. The color is removed with a few crystals of ammonium sulfate and the ammonia is allowed to

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39 evaporate under a stream of nitrogen. The residue is dissolved in a mixture of dilute hydrochloric acid and ethyl acetate. The organic layer is dried and evaporated to dryness in vacuo to give the title compound, Rf = 0.35 (silica gel, benzene / acetic acid 3: 1),

Rf = 0.5 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1) identical to the compound of Example 23.

Example 73 a) 3-Triphenylmethylthio-2-methylpropanoic acid

A solution of 1.2 g of 3-mercapto-2-methylpropanoic acid and 2.9 g of triethyl chloride in 50 ml of methylene chloride is kept at room temperature for 2 hours. The mixture is heated in a steam bath for 20 minutes and then evaporated to dryness in vacuo and the residue is dissolved in saturated aqueous sodium bicarbonate and the solution is washed with ethyl acetate. The aqueous phase is acidified to pH 3 and extracted with ethyl acetate. The organic layer is dried and evaporated to dryness to give the title compound. R f = 0.8 (silica gel, benzene / acetic acid 3: 1).

b) 1- [3- (Triphenylmethylthio) -2-methylpropanoyl] -L-proline-tert-butyl ester

By using 3-triphenylmethylthio-2-methylpropanoic acid in place of the 3 - [(4-methoxyphenyl) methylthio] -2-methylpropanoic acid in the process described in Example 64 (b), the title compound is obtained.

c) 1- [3- (Triphenylmethylthio) -2-methylpropanoyl] -L-proline 1.8 g of 3-triphenylmethylthio-2-methylpropanoic acid and 0.8 g of Ν, Ν'-carbonyldiimidazole are dissolved in 10 ml of tetrahydrofuran with stirring. at room temperature. After 20 minutes, the solution is added to a mixture of 0.6 g of L-proline and 1 g of N-methylmorpholine in 20 ml of dimethylacetamide. The resulting mixture is stirred overnight at room temperature, evaporated to dryness and the residue dissolved in a mixture of ethyl acetate and 10% aqueous potassium bisulfate. The organic layer is separated and dried and evaporated to dryness in vacuo to give the title compound. = 0.4 (silica gel, benzene / acetic acid 3: 1), Rf 1.0 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1).

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D) 1- [3-Mercapto-2-methylpropanoyl) -L-proline 5 g of 1- [3- (triphenylmethylthio) -2-methylpropanoyl] -L-proline tert-butyl ester is dissolved in a mixture of 55 ml of anisole and 110 ml of trifluoroacetic acid. After standing for 1 hour at room temperature, the solvents are removed in vacuo and the residue is added to a column of silica gel and eluted with benzene / acetic acid (75:25). The fractions corresponding to the component with Rf 0.40 (TLC silica gel with the same system) are combined and evaporated to dryness to give the title compound. Rf 0.62 (silica gel, chloroform / methanol / acetic acid / water 50:40:10) identical to the compound of Example 23.

Example .74 a) 3- (Tetrahydropyran-2-ylthio) -2-methylpropanoic acid

To a solution of 2.4 g of 3-mercapto-2-methylpropanoic acid and 1.9 g of freshly distilled 2,3-dihydro-4H-pyran in 60 ml of benzene is added 2.8 g of boron trifluoride etherate. After two hours, 4 g of potassium carbonate are added, the mixture is stirred and filtered. The filtrate is evaporated to dryness to give the title compound.

b) 1- [3- (Tetrahydropyran-2-ylthio) -2-methylpropanoyl-L-proline Using 3- (tetrahydropyran-2-ylthio) -2-methylpropanoic acid instead of the 3-triphenylmethylthio-2-methylpropanoic acid at the in Example 73 (c), the title compound is obtained. Rf: 0.8 (silica gel, benzene / acetic acid 3: 1). Rf 0.75 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1).

c) 1- (3-Mercapto-2-methylpropanoyl) -L-proline

A solution of 1 g of 1- [3- (tetrahydropyran-2-ylthio) -2-methylpropanoyl) -L-proline in a mixture of 25 ml of methanol and 25 ml of concentrated hydrochloric acid is left at room temperature for 30 minutes. The solvents are removed in vacuo to give the title compound. R f 0.35 (silica gel, benzene / acetic acid 3: 1), R f 0.5 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1) identical to the compound of Example 23.

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41

Example 75 a) 3-Acetamidomethylthio-2-methylpropanoic acid 2.4 g of 3-mercapto-2-methylpropanoic acid and 1.8 g of N-hydroxymethylacetamide are dissolved in trifluoroacetic acid and the solution is left at room temperature for one hour. The trifluoroacetic acid is removed in vacuo and the residue is dried in vacuo over potassium hydroxide to give the title compound.

b) 1- [3- (Acetamidomethylthio) -2-methylpropanoylJ-L-proline

By using 3-acetamidomethylthio-2-methylpropanoic acid in place of the 3- (tetrahydropyran-2-ylthio) -2-methylpropanoic acid by the process described in Example 74b), the title compound is obtained. Rf 0.2 (silica gel, benzene / acetic acid 3: 1). 0.3 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1).

c) 1- (3-Mercapto-2-methylpropanoyl) -L-proline 1.4 g of 1- [3- (acetamidomethylthio) -2-methylpropanoyl] -L-proline and 1.93 g of mercury acetate are dissolved in a mixture of 25 ml of acetic acid and 25 ml of water. After stirring for one hour on a steam bath, hydrogen sulfide is bubbled again until no more precipitation of mercury sulfide is observed. The mixture is filtered, the precipitate is washed with ethanol and the filtrate is evaporated to dryness in vacuo to give the title compound. R f: 0.35 (silica gel, benzene / acetic acid 3: 1); Rf: 0.5 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1) identical to the compound of Example 23.

Example 76 1- (3-Mercapto-2-methylpropanoyl) -L-proline tert-butyl ester To the 5 ° C cold solution of 1.2 g (10 mmol) of 3-mercapto-2-methylpropanoic acid and 1, 7 g (10 mmol) of L-proline tert-butyl ester in 25 ml of dichloromethane are added 2.26 g of dicyclohexylcarbodiimide in 5 ml of dichloromethane in portions. After two hours at room temperature, 5 drops of acetic acid are added, the mixture is filtered and the filtrate is evaporated to an oily residue. This residue is taken up in 20 ml of petroleum ether / ethyl acetate (3: 1) and placed in a 150 ml silica gel column made of petroleum ether. the fraction eluted with petroleum ether / ethyl acetate

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42 (1: 1) contains the title mentioned in the title. This 0.6 g weight is dried over P2 ° 5 1 vacuum for 12 hours. Rf 0.6 (silica gel, benzene / acetic acid 3: 1), Rf 0.8 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1).

Example 77 1- (3-Mercapto-2-methylpropanoyl) -L-proline Using 1- (3-mercapto-2-methylpropanoyl) -L-proline tert.-butyl ester instead of 1- (3-mercaptopropanoyl) The L-proline tert-butyl ester by the procedure described in Example 13 C gives the title compound. Rf 0.35 (silica gel, benzene / acetic acid 3: 1), Rf 0.8 (silica gel, methyl ethyl ketone / acetic acid / pyridine / water 14: 1: 2: 1).

Example 7 8 1- (3-Mercapto-2-methylpropanoyl) -L-proline Using 1- (3-mercapto-2-methylpropanoyl) -L-proline tert.-butyl ester instead of 1- (3- The mercaptopropanoyl) -L-proline tert-butyl ester by the procedure described in Example 13 C * gives the title compound. R f 0.35 (silica gel, benzene / acetic acid 3: 1), R f 0.5 (silica gel, methyl ethyl ketone / acetic acid / pyrdine / water 14: 1: 2: 1) identical to the compound prepared in Example 23 .

The racemic form of the final product in all the preceding examples is prepared by using the DL form of the amino acid starting material instead of the L form.

Similarly, in the previous examples, the D-form of the final products is prepared by using the D-form of the amino acid starting material instead of the L-form.

Claims (26)

1. Analogous process for preparing a proline derivative of formula R3. , In R4 R1 H2C- (CH) 2, II II R2-S- (CH) n-CH-CO-N-CH-COR (I) wherein R is hydroxy, amino or c1-C7 alkoxy, R1 and R4 is each hydrogen, alkyl, phenyl or benzyl, R 2 is hydrogen, 0 M 5 in 5 11 r5-c-, r5-mc-, R6-S- or R7, R3 is hydrogen, hydroxy or C1- C4 alkyl, R5 is C1-C4 alkyl, phenyl or phenyl-cl -C 4 alkyl, R 6 is C 1 -C 7 alkyl or phenyl optionally substituted with halogen, methyl or methoxy, M is 0 or S, n is 0 or 1, R 7 is R 3 1 4 4 (HC) -CH 2 R1-R4 1111 R-OC-HC-N-CO-CH- (CH) nS wherein R, R1, R3, R4 and n have the above meanings, characterized in that a) a compound of formula III R3 H2C- ( CH) 2 II HN-CH-COR (III) wherein R and R3 have the above meanings are acylated with an acid of formula IV R4 R1> ii R2-S- (CH) n-CH-COOH (IV) wherein R1 , R 2, R 4 and n have the above meanings, or a reactive derivative thereof, or b) a compound of formula R 3 H2 C - (CH) 2 HN-CH-COR wherein R and R 3 have the above meanings , is acylated with an acid of the formula V R4 R1 II X- (CH) n-CH-COOH (V) wherein r1, R4 and n have the meanings given above, X is bromine, chlorine, iodine or tosyloxy and the resulting product is then subjected to a substitution reaction with the anion of a thiol or thioic acid of formula VII R2-SH (VII) c) a compound of formula R3 H2C- (CH) 2 HN-CH-COR wherein R and R 3 has the above meanings, is acylated with an acid of formula VI R 4 R 1 II CH = C-COOH (VI) wherein R 1 and R 4 have the above meanings, and that the resulting product is then subjected to an addition reaction with the anion of thiol or thioic acid of formula R2-SH, in which R2 has the meaning given above, to form the compound of formula I wherein n is 1, or d) a compound of formula III R3 H2C- (CH) 2 (III) II HN-CH -COR wherein R and R3 have the above meanings are acylated with a compound of the formula in DK 157487 B R4 R1 II ch2-ch II s-c = o wherein R1 and R4 have the above meanings to form compounds of the formula I, where n is 1 and R2 is hydrogen, or e) a compound of Formula III R3 H2C ~ (CH) 2 (III) II HN-CH-COR wherein R and R3 have the meanings given above are acylated with a mercaptoalkanoic acid of formula IX R4 R1 II YS- (CH) n-CH-COOH ( IX) wherein R1, R4 and n have the above meanings and Y is R2 or a protecting group R1 R4 CH30- (q) -CH2-, C '' CH3CONHCH2 or R-O-CH- (CH) nS then removed by conventional methods to form a compound of formula I wherein R 2 is hydrogen and then, if desired, ammonylates a prepared compound of formula I wherein R 2 is R 5 CO- wherein R 5 has the meaning given above, to form a compound of formula I wherein R 2 is hydrogen and, if desired, a prepared compound of formula I wherein R 2 is hydrogen having the halogenated compound M 5 R 5-mcx wherein R 5 and M have the meanings given above; and X is halogen to give a compound of formula I wherein R 2 is M 5 11 r 5-mc-. DK 157487 B Process according to claim 1, characterized in that the product has the formula 2. n R -S- (CH) n-CH-CO-N-COR where R is hydroxy or C 1 -C 6 alkoxy, R 1 is hydrogen or C C 1 -C 6 alkyl, R 2 is hydrogen, C 1 -C 7 alkylthio or C 2 -C 6 alkanoyl, n is 0 or 1. Process according to claim 2, characterized in that R is hydroxy. Method according to claim 2, characterized in that n is 1. Process according to claim 2, characterized in that R 2 is hydrogen or C 2 -C 8 alkanoyl. Process according to claim 2, characterized in that R 2 is hydrogen. Process according to claim 2, characterized in that R 2 is acetyl. Process according to claim 2, characterized in that R 1 is hydrogen or (C 1-4 alkyl). Process according to claim 2, characterized in that R 1 is hydrogen or methyl. Process according to claim 2, characterized in that R is hydroxy and R 1 is hydrogen or methyl. A process according to claim 2, characterized in that R is hydroxy, R 1! is hydrogen or methyl, R 2 is hydrogen or acetyl, and n is 0 or 1. DK 157487 B Process according to amber 2, characterized in that R is hydroxy, R 1 and R 2 are each hydrogen and n is 0. Process according to claim 2, characterized in that R is hydroxy, R 1 is hydrogen, R 2 is acetyl and n is 1. Process according to claim 2, characterized in that R is hydroxy, R 1 is methyl, R 2 is acetyl, and n is 1. Process according to claim 2, characterized in that R is hydroxy, R 1 and R 2 are each hydrogen and n is 1. Process according to claim 2, characterized in that R is hydroxy, R 1 is methyl, R 2 is hydrogen and n is 1. Process according to claim 2, characterized in that R is hydroxy, R 1 is hydrogen, R 2 is benoyl and n is 1. Method according to claim 2, characterized in that the product is in L-shape. Method according to claim 16, characterized in that the proline is in L-form. Process according to claim 2, characterized in that R is hydroxy, R 1 is hydrogen, R 2 is C 1 -C 6 alkylthio, and n is 1. Process according to claim 1, characterized in that R 2 is ΓΊ f 1 R-OC - N-OC-CH- (CHn) -S-2 n each R is hydroxy, each R 1 is hydrogen or C 1 -C 7 alkyl, and each n is 0 or 1. DK 157487 B Process according to claim 21, characterized in that each R is hydroxy, each R 1 is hydrogen and each n is 1. Process according to claim 1, characterized in that the product is 1- (3-mercapto-2-D-methylpropanoyl) -L-proline (cap-topril) of the formula H3 p in HS-CH2-CH-CO-N1- COOH (a). (B) Process according to claim 1, characterized in that the product is 1,1 '- [dithiobis- (2-D-methyl-3-propanoyl)] - bis-L-proline. The method according to claim 15, characterized in that the proline is in L-form. Method according to claim 16, characterized in that the proline is in L-form.