CH622503A5 - Processes for the preparation of proline derivatives and of related compounds - Google Patents

Description

The present invention relates to processes for the preparation of proline derivatives and related compounds of general formula I:

R,

r4

r,

H2C- (CH) „

55

R2-S- (C H) n-C H-CO-N — C H-COR * * *

wherein R is a hydroxyl group, NH2 or lower alkoxy; R 1 and R 4 are each a hydrogen atom, a group 1 lower alkyl, phenyl or phenyl-lower alkyl; R2 is a hydrogen atom, a lower alkyl, phenyl, substituted phenyl group where the substituent of the phenyl group is a halogen atom, a lower alkyl or lower alkoxy group, phenyl-lower alkyl, diphenyl-lower alkyl, triphenyl- lower alkyl, lower alkyl-thiomethyl, phenyl-lower alkyl-thiomethyl, lower alkanoyl-amidomethyl,

O

m m

60

R5-C -, Rj-M-C -, R5-NH-C -, R6 — S- or R7; R3 is a hydrogen atom, a hydroxyl or lower alkyl group; R5 is a lower alkyl, phenyl or phenyl-lower alkyl group; R6 is lower alkyl, phenyl, substituted phenyl 65 (where the substituent of the phenyl group is a halogen atom, a lower alkyl or lower alkoxy group), hydroxy-lower alkyl or aminocarboxy-lower alkyl; R7 is a group i

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4

R.

n (HC) CH2

o) R is a hydroxyl group, R] is a hydrogen atom, R2 is a lower alkyl-thio group and n = 1 p) R2 is the group

Ri

I

R.

R-OC-HC —N-CO-C H - (C H) n-S (0) p;

* * *

M is O or S; m = 1 to 3; n and p each have the value 0 to 2.

The asterisks indicate asymmetric carbon atoms. Each of the carbon atoms carrying a substituent Rt, R3 and R4 is asymmetric when this substituent is other than hydrogen.

In its broad aspect, the invention includes proline and related derivatives of formula I above. In this large group, because of their properties, certain subgroups are preferred over others.

In general, the compounds of formula I are preferred in which R is a hydroxyl or lower alkoxy group;

Rj is a hydrogen atom or a lower alkyl group; R2 is a hydrogen atom, an R5-CO-, R6-S- or R7 group; R3 and R4 are each a hydrogen atom; R5 is a lower alkyl group, in particular methyl or phenyl; Rg is a lower alkyl group, in particular methyl or ethyl; m = 2, n = 0.1 or 2 and especially 1; and R7 where R, Rb R3, R4, m and n have the same preferences as above and p = 0.

Particularly preferred are the compounds of formula II:

ROCK'

n r,

N - OC - C H - (CH2) n-S-;

10

Ri

I

R2-S- (CH2) n-C H-CO-N-

*

HORN

wherein R is a hydroxyl or lower alkoxy group; Rj is a hydrogen atom or a lower alkyl group; R2 is a hydrogen atom, R5-CO-, R6-S- or R7; R5 is a lower alkyl or phenyl group, and in particular lower alkyl; R6 is a lower alkyl group; and n = 0.1 or 2.

In the group of compounds represented by formula II, the following subgroups are even more preferred in order (a to r), preferably increasing for the compounds which are preferred embodiments:

a) R is a hydroxyl group b) n = 1

c) R2 is a hydrogen atom or a lower alkanoyl group d) R2 is a hydrogen atom e) R2 is an acetyl group f) R, is a hydrogen atom or a lower alkyl group g) R! is a hydrogen atom or a methyl group h) R is a hydroxyl group, R] is a hydrogen atom or a methyl group i) R is a hydroxyl group, Rj is a hydrogen atom or a methyl group, R2 is a hydrogen atom or an acetyl group and n = 0.1 or 2

j) R is a hydroxyl group, R! and R2 each represents a hydrogen atom and n = 0

k) R is a hydroxyl group, Rj is a hydrogen atom, R2 is an acetyl group and n = 1

1) R is a hydroxyl group, Rj is a methyl group, R2 is an acetyl group and n = 1

m) R is a hydroxyl group, R, and R2 each represent a hydrogen atom and n = 1

n) R is a hydroxyl group, R, is a methyl group, R2 is a hydrogen atom and n = 1

each R is a hydroxyl group; Rj is a hydrogen atom or a lower alkyl group, especially hydrogen or a methyl group; and n has the value 0 to 2 and in particular 1

M

q) R2 is a group R5-M-C - where M is O or S

M

R) R2 is a group R5-NH-C - where M is O or S and preferably S.

It will be understood that combinations of the foregoing, where applicable, are among the preferred groups.

Particularly preferred are the stereoisomers in which the proline is in the L- form.

Lower alkyl groups represented by either variant include straight or branched chain hydrocarbon groups ranging from methyl to heptyl, for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl , pentyle, isopentyle, etc. The lower alkoxy groups are of the same kind having from 1 to 7 carbon atoms linked to oxygen, for example methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t-butoxy, etc. Preferred are those at c, -c4, especially Ci and C2 of the two types. The phenylmethyl group is the preferred phenyl-lower alkyl group.

The lower alkanoyl groups are those having the acyl groups of the lower fatty acids in Q-C7, for example acetyl, propionyl, butyryl, isobutyryl, etc. Likewise, lower alkanoyl groups having up to 4 carbon atoms and in particular the acetyl group are preferred.

The four common halogens are included by the term "halogen" but chlorine and bromine are preferred. The substituted phenyl groups preferably carry the substituent in the 4- position of the ring. The hydroxy-lower alkyl groups have a hydroxyl group on an alkyl chain such as those described above, in particular on the terminal carbon atom, for example hydroxymethyl, 2-hydroxyethyl, etc. The aminocarboxy-lower alkyl groups have an amino group and a carboxy group on a lower alkyl group such as those described above and preferably both on a carbon atom, for example on the terminal carbon atom as in the group Preferred 2-amino-2-carboxyethyl.

The products of formula I and the preferred subgroups can be prepared by various synthetic methods. 55 The methods according to the invention are defined in claims 1 and 13. According to the first method, the compounds of formula I are prepared by acylation of a compound of formula III:

R3 I

H2C— (C H) m

I I HN - C H-COR

with an acid of formula IV:

at

5

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r4 rj

I I R2-S- (C H) n-C H-COOH

or its chemical equivalent.

Thus, the final product can be prepared not only by direct acylation with an acid of formula IV, but also by intermediates such as (a) w-halo-alkanoic acids of formula V:

r4

I

Ri

X- (C H) „- C H-COOH

in which X is a bromo, chloro or iodo radical, or (b) a tosyloxyalkanoic acid, i.e. X in formula V

is a tosyloxy group (CH3-

-S020-) or (c) a substituted acrylic acid of formula VI:

R4 R]

I I

C H = C-COOH

The product of this acylation is then subjected to a displacement or an addition with the anion of a thiol or thioacid of formula VII:

R2-SH

The acylation can also be carried out with a thiolactone of formula VIII:

R4 R]

I I (C H2) n — C H

wo in which n = 1 or 2, or a mercapto-alkanoic acid of formula IX:

r4

I

r,

Y-S- (C H) n-C H-COR

in which Y is R2 or, moreover, if a product of formula I is desired in which R2 is a hydrogen atom, then Y can also be a protective group such as:

(a) CH3O-

-CH2—,

(b)

CX,

(c) CH3CONHCH2,

r, r4

I I

(d) R-O-C-C H- (C H) „- S-

or another sulfur protecting group. "Deprotection" can be carried out by known means such as treatment with hot trifluoroacetic acid, cold sulfuric trifluoromethane acid, mercuric acetate, sodium in liquid ammonia, zinc and hydrochloric acid, etc. For a review of these methods, see "Methoden der Organischen Chemie" (Houben-Weyl), Vol. XV, part. I, page 736 and seq. (1974).

30

When the acid of formula IV is used as acylating agent, the acylation can be carried out in the presence of a coupling agent such as dicyclohexylcarbodi-imide, etc., or the acid can be activated by formation of its mixed anhydride, symmetrical anhy-i, acid chloride, acid ester or using the reagent of Woodward K, N-ethoxycarbonyI-2-ethoxy-l, 2-dihydroquinoline, etc. For an account of acylation processes, see "Methoden der Organischen Chemie" (Hou-ben-Weyl), Vol. XV, part. II, page 1 and seq. (1974). 1 Compounds of formula III include, for example, proline, hydroxyproline, 4-methylproline, pipecoli-que acid, 5-hydroxypipecolic acid, azetidine-2-carboxy-acid, their lower alkyl esters , etc. The acylation of such compounds is described in more detail below.

According to a preferred process for the preparation of compounds of formula I, in particular when R2 is the group R5-CO-, an acid or an ester of formula III is coupled with a haloalkanoic acid of formula V:

I R4 Rj I I X- (C H) n-C H-COOH

in which X is a halogen atom, preferably chlorine or bromine. It can be carried out by one of the known methods where the acid IV is activated before the reaction with the acid III, which implies the formation of a mixed anhydride, a symmetrical anhydride, an acid chloride , an active ester or the use of Woodward K's reagent, EEDQ (N-ethoxycarbo-nyI-2-ethoxy-1,2-dihydroxyquinoline), etc.

The product of this reaction is a compound of formula X:

r3

I

H2C— (C H) m r4

I

laugh I

X - (C H) n- C H- CO - N —C H-COR

The product of formula X is subjected to a displacement reaction with the anion of a thio-acid of formula VII:

R2-SH

to obtain a product of formula XI:

r3

45

r4

r,

H2C- (CH) n

I I

R2- S - (C H) n-C H - CO - N - C H-COR

When R2 is the group R5CO, we can then convert this product to product XII:

r3

R4 RJ I I HS - (C H) n- C H - CO

H2C- (CH),

-NOT

-C H-COR

by ammonolysis. When R2 is a protective group, the compound of formula XII can then be obtained by "deprotection" wl as described above. When R is an ester group (that is to say R is a lower alkoxy group), the ester group can be removed for example when R is a t-butoxy or t-amyl-oxy group by treatment of the ester of formula XI or XII with trifluoroacetic acid and anisole to obtain the corresponding free acid f-5. When other alkoxy groups are present, alkaline hydrolysis gives the corresponding acid.

According to a variant of this process, an acrylic acid of formula VI is used:

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6

r4 r,

i i

C H = C-COOH

as a starting material. This acrylic acid is first converted to an acid halide and then it is reacted with a compound of formula III to obtain a compound of formula XIII:

r3

i

R4 R, H2C- (CH) m

II II CH = C —CO —N —CH-COR

and this intermediate is subjected to the addition reaction with thiol or thio-acid VII as described above.

It is also possible to use a tosyloxyalkanoic acid of formula XIV:

R4 Rj

CH3- —S020- (C H) „- C H - COOH

as an agent for acylating the acid of formula III, then the acylation product is subjected to the displacement reaction, etc., as described above.

Alternatively, the acrylic acid of formula VI can first be reacted with the thio-acid of formula VII to obtain a product of formula XV:

R4 R,

I I

R2-S-C H-C H-COOH

which is converted to its acid halide, for example with thionyl chloride, then it is coupled to the compound of formula III and the same sequence is then carried out as above.

The acid or ester of formula III can also be acylated with a “protected” form of an o-mercapto-alkanoic acid of formula XVI:

R4 Rj

I I Rg-S- (C H) n-C H-COOH

in which R8 is the "protecting" group. Such "protecting" groups can have the form described above.

After acylation, the product can be "deprotected" by one of the known methods mentioned above.

Another acylating agent can be a thiolactone, for example ß-propiothiolactone, a-nrethyl-ß-propiothiolac-tone, etc.

Further details of the preferred modes of preparation of the present compounds will be found in the following and in the examples.

According to a variant which is particularly preferred, the acid or the ester of formula III is acylated with a halo-alkanoyl halide of formula XVII:

R4 R!

I I X- (C H) n-C H-COX

in which each X is independently a halogen atom, preferably chlorine or bromine, Ri is a hydrogen atom, a lower alkyl or phenylalkyl group and n = 0.1 or 2. This reaction is carried out in a alkaline medium, for example a dilute solution of alkali metal hydroxide, an alkali metal bicarbonate or an alkali metal carbonate solution at reduced temperature, for example about 0 ° to 15 ° C. The reaction product is subjected to a displacement with the anion of the thiol or thio-acid of formula VII above also in an alkaline medium, preferably an alkali metal carbonate solution, then treatment is carried out in a known manner. The product of this reaction where R2 in formula I is R5-CO is converted into the product where R2 is a hydrogen atom by ammonolysis, for example an alcoholic solution of ammonia or concentrated ammonium hydroxide or by hydrolysis alkaline, for example with an aqueous hydroxide of a metal. When an acid of formula III is used as starting material, the final product obtained as free carboxylic acid can then be converted into its ester, for example by esterification with a diazo-alkane such as diazomethane, a 3-alkyl -p-tolyl-triazene such as ln-butyl-3-p-tolyltria-zene, etc. Treatment of an ester, preferably methyl ester, with an alcoholic solution of ammonia, converts the free acid to the amide, i.e. R is NH2.

According to another variant, an ester, preferably the t-butylester of formula III, is treated in an anhydrous medium such as dichloromethane, tetrahydrofuran, dioxane, etc. with a thio-alkanoic acid of formula XVIII:

r!

i

R2-S- (CH2) n— C H -COOH

in the presence of dicyclohexylcarbodi-imide, N, N'-carbonyl-bis-imidazole, ethoxyacetylene, diphenylphospho-ryl azide or similar coupling agents at a temperature between about 0 and 10 ° C. It is then possible to remove the ester group R, for example by treatment with trifluoroacetic acid and anisole at approximately room temperature.

When an ester of formula III (for example R is a lower alkoxy group, in particular t-butoxy) is acylated with a thiolactone, for example ß-propiothiolactone, α-methyl-ß-propiothiolactone, etc. conduct the reaction in an anhydrous solvent such as tetrahydrofuran, dioxane, methylene chloride, etc., at a temperature of about 0 ° C at room temperature. The ester group can be removed with anisole and trifluoroacetic acid as described above.

M II

Similarly, when R2 is the group Rs-M-C -, products of formula I carrying this substituent are formed by reacting a compound of formula XII with the halogenated compound XIX:

M

II

R5-M-C -X

or, alternatively, reacting a compound of formula X with an alkali metal salt or an alkaline earth metal salt of formula XX:

M

II

R5-M-C —S-Me in which Me represents the alkali metal or the alkali metal.

M II

When R2 is the group R5-NH-C -, products of formula I having this substituent are prepared by reacting a

5

10

15

20

25

30

35

40

45

50

55

60

fi5

7

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compound of formula XII with the appropriate isocyanate or substituted isothiocyanate of formula XXI:

R5-N = C = M

As a variant, the same products can be prepared by coupling an acid of formula XXII:

M R4 Ri Il I!

R, -NH-C -S- (C H) n- C H-COOH

with an amino acid of formula III.

Compounds of formula I are prepared in which R2 is a lower alkyl, phenyl, substituted phenyl, lower phenylalkyl, triphenyl lower alkyl, lower alkyl-thiomethyl or phenyl lower alkyl-thiomethyl by reacting a compound of formula XII with the corresponding halide R2X or by reacting a compound of formula X with the corresponding thiol R2SH as described above.

When R2 is a lower alkanoyl-amidomethyl group, the compound of formula II is prepared by condensation of a compound of formula XII with the corresponding hydroxymethyl-lower alkanoyl-amide of formula XXIII:

lower alkyl-CO-NHCH2OH

in the presence of an acid catalyst such as trifluoroacetic acid.

Products of formula I in which R2 is the group R6-S can be prepared by any of the known methods for the synthesis of mixed disulfides, for example by the reaction of a compound of formula XII with a thiosulfinate of formula XXIV , a thiosulfonate of formula XXV, a sulfenyl halide of formula XXVI, a thiosulfate of formula XXVII or a sulfenyl thiocyanate of formula XXVIII.

O

O

(XXIV) R6-S -S-R6, (XXV) R6-S -S-R6, (XXVI) R6S-X,

II

o

(XXVII) R6-S-S03H, (XXVIII) R6-S-SCN In the particular case where R7 is:

r3

I

R4 R, CH2— (C H) n Il II -S (0) p- (C H) n- C H- CO - N C H-COR,

R, Rj, R3 and R4 are the same as the corresponding substituents in formula I and p = 0, symmetrical disulfides can be obtained by direct oxidation of a compound of formula XII with iodine. When p = 1 or 2, these products are obtained by the stepwise oxidation of the corresponding compound where p = 0. Mixed disulfides are obtained by the modification indicated in the examples.

The products of formula I have one or more asymmetric carbon atoms. When Rx, R3 or R4 is other than hydrogen, the carbon atom to which it is attached is asymmetric. These carbon atoms are indicated by an asterisk in formula I. Thus, the compounds exist in stereoisomeric forms or in their racemic mixtures. All of these are within the scope of the invention. The synthesis described above can use the racemate or one of the enantiomers as starting material. When the racemic product is used as a starting material for the synthesis process, the stereoisomers obtained in the product can be separated by conventional methods of chromatography or fractional crystallization. In general, the L— isomer relative to the carbon atom of the amino acid represents the preferred isomer form. We prefer ? also the D- isomer with respect to the carbon atom a in the acyl side chain (that is to say the carbon atom bearing ri).

The present compounds form basic salts with various inorganic and organic bases which are also within the scope of the invention. These salts include ammonium salts, alkali metal salts such as the preferred sodium and potassium salts, alkaline earth metal salts such as calcium and magnesium salts, salts with bases organic, e.g. dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, hydrabamine salts, salts with amino acids such as arginine, lysine, etc. Physiologically acceptable non-toxic salts are preferred although other salts are also useful, for example to isolate or purify the product as illustrated in the examples in the case of the dicyclohexylamine salt.

The salts are formed in known manner by reacting the product in the form of free acid with one or more equivalents of the appropriate base providing the desired cation in a solvent or a medium in which the salt is insoluble or in water, then separating the water by lyophilization. By neutralizing the salt with an insoluble acid such as a cation exchange resin in hydrogen form (for example, a polystyrene-sulfonic acid resin such as "Dowex 50") or with an aqueous acid and then extraction with an organic solvent , for example ethyl acetate, dichloromethane, etc., the product can be obtained in the form of free acid and, if desired, another salt can be formed.

Further experimental details are found in the examples which are preferred embodiments and which also serve as a model for the preparation of other members of the group.

The present compounds inhibit the conversion of the decapepid which is angiotensin I into angiotensin II and therefore they are useful for reducing or relieving hypertension in relation to angiotensin. The action of renin which is an enzyme on 40 angiotensinogen which is a pseudoglobulin in the blood plasma, produces angiotensin I. Angiotensin I is converted by an enzyme converting angiotensin (ACE) into angiotensin II. The latter is a substance which is a hypertensive and which has been implicated as the causative agent of various forms of hypertension in various species of mammals, for example rats and dogs. The present compounds are involved in the sequence angiotensin (renin) - »angiotensin I -» angiotensin II by inhibiting the enzyme which converts angiotensin and by reducing or suppressing the formation of angiotensin II. Thus, by the administration of a composition containing one or more of the compounds of formula I or one of their physiologically acceptable salts, the hypertension which depends on angiotensin in the mammalian species which suffer from it is relieved. A single dose or preferably two to 55 four daily shared doses given at about 0.1 to 100 mg per kg per day and preferably 1 to 50 mg per kg per day are suitable for reducing blood pressure as indicated in the animal model experiments described by SL Engel, TR Schaeffer, MH Waugh and B. Rubin, Proc. 60 Soc. Exp. Biol. Med. 143.483 (1973). Preferably, the substance is administered orally but it is also possible to use parenteral routes such as the subcutaneous, intramuscular, intravenous or intraperitoneal route.

The present compounds can be used to obtain the reduction of blood pressure by putting them into composition for forms such as tablets, capsules or elixirs for oral administration or in solution or suspension.

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sterile for parenteral administration. Approximately 10 to 500 mg of a compound or a mixture of compounds of formula I or their physiologically acceptable salt is composed with a vehicle, an excipient, a binding agent, a preservative, a stabilizing agent, a flavor , etc., physiologically acceptable in a unit dosage form satisfying established pharmaceutical practice. The amount of active substance in these compositions or preparations is such that an appropriate dose in the range indicated is obtained.

Examples of the adjuvants which can be incorporated into tablets, capsules, etc. are the following: a binding agent such as gum tragacanth, acacia, corn starch or gelatin; an excipient such as dicalcium phosphate; a disintegrating agent such as corn starch, potato starch, alginic acid, etc; a lubricating agent such as magnesium stearate; a sweetening agent such as sucrose, lactose or saccharin; an aroma such as the essence of peppermint, the essence of wintergreen or cherry. When the unit dose form is a capsule, it may contain, in addition to the abovementioned substances, a liquid vehicle such as a fatty oil. Various other substances may be present as coatings or to otherwise modify the physical form of the dose unit. For example, the tablets can be coated with shellac, sugar or both. A syrup or elixir may contain the active compound, saccharose as a sweetening agent, methyl and propyl paraben as a preservative, a color and an aroma such as that of cherry or orange.

Sterile compositions for injection can be prepared according to established pharmaceutical practice by dissolving or suspending the active substance in a vehicle such as water for injection, a natural vegetable oil such as sesame oil , coconut oil, peanut oil,

cottonseed oil, etc., or a synthetic fatty vehicle such as ethyl oleate, etc., or a synthetic fatty vehicle such as ethyl oleate, etc. Buffering agents, preservatives, antioxidants, etc. can be incorporated as required.

The following examples illustrate the invention. All temperatures are in degrees centigrade. 40

Example 1

l- (2-benzoylthio-acetyl) -L-proline 45

5.75 g of L-proline are dissolved in 50 ml of sodium hydroxide N and the solution is cooled in an ice-water bath. 26 ml of 2N sodium hydroxide and 5.65 g of chloroacetyl chloride are added, then the mixture is vigorously stirred at room temperature for 3 h. A suspension of 7.5 g of thiobenzoic acid and 4.8 g of potassium carbonate in 50 ml of water is added. After 18 h of stirring at room temperature, the reaction mixture is acidified and extracted with ethyl acetate. The ethyl acetate layer is washed with water, dried over magnesium sulfate and washed.

concentrated to dryness under vacuum. The 14.6 g of residue are dissolved in 150 ml of ethyl acetate and 11 ml of dicyclohexylamine are added. The crystals are filtered and recrystallized from ethyl acetate to obtain 5.7 g which melts at 151-152 ° C. To convert the salt to the acid, the crystals are dissolved in a glass (f) (1

mixture of 100 ml of 5% aqueous potassium bisulfate and 300 ml of ethyl acetate. The organic phase is washed once with water, dried over magnesium sulfate and concentrated to dryness under vacuum to obtain 3.45 g.

Example 2 l- (2-mercapto-acetyl) -L-proline

3.4 g of 1- (2-benzoylthio-acetyl) -L-proline are dissolved in a mixture of 10.5 ml of water and 6.4 ml of concentrated ammonia. After 1 h, the reaction mixture is diluted with water and then 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 concentrated to dryness to give 1.5 g. The product, i.e. 1- (2-mercapto-acetyl) -L-proline, is crystallized from ethyl acetate; it melts at 133-135 ° C.

Example 3

1- (2-Benzoylthio-acetyl) -L-proline methyl ester

The 1- (2-benzoylthio-acetyl) -L-proline obtained in Example 1 is dissolved in methanol and an ethereal solution of diazomethane is added until there is a persistent yellow color. After 15 min a few drops of acetic acid are added and the solvent is removed in vacuo to obtain the methyl ester of 1- (2-benzoylthio-acetyl) -L-proline.

Example 4 1- (2-Mercaptoacetyl) -L-proline amide

The product of Example 3 is dissolved in 10% methanolic ammonia and the solution is kept at room temperature in a pressure-tolerant flask. When the analysis by thin layer chromatography indicates that the two ester functions are ammonolysed, the reaction mixture is concentrated to dryness to obtain the amide of 1- (2-mercapto-acetyl) -L-proline.

Examples l- (2-benzoylthio-acetyl) -L-hydroxyproline

By substituting L-hydroxyproline for L-proline in the process of Example 1, l- (2-benzoylthioacetyl) -L-hydroxyproline is obtained.

Example 6 1 - (2-mercapto-acetyl) -L-hydroxyproline

By treating the product of Example 5 with ammonia as in Example 2, we obtain l- (2-mercapto-acetyl) -L-hydroxyproline.

Example 7

1- (2-Benzoylthio-acetyl) -L-azetidine-2-carboxylic acid By substituting L-azetidine-2-carboxylic acid for L-proline in the process of Example 1, the acid 1 is obtained - (2-benzoylthio-acetyl) -L-azetidine-2-carboxylic.

Example 8

1 - (2-mercapto-acetyl) -L-azetidine-2-carboxylic acid

By treating the product of Example 7 with ammonia as in Example 2, we obtain l- (2-mercapto-acetyl) -L-azetidine-2-carboxylic acid.

Example 9

1- (2-Benzoylthio-acetyl) -L-pipecolic acid

By substituting L-pipecolic acid for L-proline in the process of Example 1, l- (2-benzoylthio-acetyl) -L-pipecolic acid is obtained.

Example 10 Acid 1 - (2-mercapto-acetyl) -L-pipecolic

By treating the product of Example 9 with ammonia as in Example 2, we obtain l- (2-mercapto-acetyl) -L-pipecolic acid.

Example 11

l- (2-benzoylthiopropanoyl) -L-proline

5.75 g of L-proline are dissolved in 50 ml of hydroxide

9

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aqueous sodium N and the solution is refrigerated in an ice bath with stirring. 25 ml of 2N sodium hydroxide and 8.57 g of 2-bromopropionyl chloride are added in this order and the mixture is removed from the ice bath and stirred at room temperature for 1 h. A mixture of 7.5 g of thiobenzoic acid and 4.8 g of potassium carbonate in 50 ml of water is added and the mixture is stirred overnight at room temperature. After acidification with concentrated hydrochloric acid, the aqueous solution is extracted with ethyl acetate and the organic phase is washed with water, dried and concentrated to dryness. The 14.7 g of residue are chromatographed on a 440 g of silica gel column with a 7: 1 mixture of benzene: acetic acid. The fractions containing the desired substance are combined, concentrated to dryness and the residue is precipitated twice with ether-hexane and it is converted to a dicyclohexylamine salt in ether-hexane and 9.4 is obtained. g which melt at (142) 148-156 ° C. The dicyclohexylamine salt is reconverted to the acid as in Example 1 and 5.7 g are obtained.

Example 12 l- (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 1 h, the mixture is diluted with 10 ml of water and filtered. The filtrate is extracted twice with ethyl acetate, it is concentrated to one third of the original volume, it is acidified with concentrated hydrochloric acid and it is extracted with ethyl acetate. The organic phase is washed with saturated sodium chloride, dried and concentrated to dryness under vacuum. The residue is crystallized, that is to say l- (2-mercaptopropanoyl) -L-proline from a mixture of ethyl acetate and hexane and 3 g are obtained which melt ( 105) at 116-120 ° C.

Example 13

l- (3-benzoylthiopropanoyl) -L-proline

5.75 g of L-proline are dissolved in 50 ml of normal sodium hydroxide and the solution is refrigerated 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 min in the ice bath and then 3 h at ordinary 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 h at room temperature. After acidification with concentrated hydrochloric acid, the aqueous phase is extracted twice with ethyl acetate. The organic layers are dried over magnesium sulphate and concentrated to dryness under vacuum to obtain l- (3-benzoylthiopropanoyl) -L-pro-line; 7.1 g are obtained which melts at 101-102 ° C (ethyl acetate-hexane).

Example 14 L-proline tert-butyl ester

230 g of L-proline are dissolved in a mixture of 1 liter of water and 400 ml of 5N sodium hydroxide. The solution is refrigerated in an ice bath and then, with vigorous stirring, 460 ml of 5N sodium hydroxide and 340 ml of benzyloxycarbonyl chloride in five aliquots are added over the course of 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 and dried. 442 g are obtained, which melts at 78-80 ° C.

The 180 g of the benzyloxycarbonyl-L-proline thus obtained are 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 stirred in a pressure bottle for 72 h. 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 concentrated to dryness under vacuum to obtain 205 g of benzyloxycarbonyl-L-5 proline t-butyl ester.

205 g of benzyloxycarbonyl-L-proline t.butyl ester are dissolved in 1.2 liters of absolute ethanol and hydrogenated at normal pressure with 10 g of 10% palladium on carbon until only a trace of carbon dioxide in the hydrogen-io which is the exit gas (24 h). The catalyst is filtered off and the filtrate is concentrated in vacuo to 30 mm Hg. The residue is distilled in vacuo to obtain the L-proline t-butyl ester which boils at 50-51 ° C / l mm.

15 Example 15

1- (3-acetylthiopropanoyl) -L-proline tert-butylester

5.13 g of L-proline t-butylester are dissolved in 40 ml of dichloromethane and the solution is refrigerated in an ice-water bath. A solution of 6.18 g of dicyclohexylcarbo-2o di-imide in 20 ml of dichloromethane is added and then immediately 4.45 g of 3-acetylthiopropionic acid are added. After 15 minutes of stirring in the ice-water bath and 16 hours at ordinary temperature, the precipitate is separated by filtration and the filtrate is concentrated to dryness under vacuum. The residue is dissolved in ethyl acetate and washed until neutral. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo to obtain 9.8 g of 1- (3-acetylthio-propanoyl) -L-proline t-butylester.

3o Example 16

l- (3-acetylthiopropanoyl) -L-proline

4.7 g of 1- (3-acetylthiopropa-nucleus) -L-proline t-butyl ester are dissolved in a mixture of 34 ml of anisole and 68 ml of trifluoroacetic acid and the mixture is kept at room temperature. -35 ordinary tures for 1 hour The solvents are removed in vacuo and the residue is precipitated from ether-hexane several times. The 3.5 g of residue is dissolved in 25 ml of acetonitrile and 2.8 ml of dicyclohexylamine are added. The crystalline salt is filtered and recrystallized from isopropanol. 3.8 g are obtained, which melt at 176-177 ° C. The salt is reconverted to l- (3-acetylthio-propanoyl) -L-proline as in Example 1 and 1.25 g is obtained which melt at 89-90 ° C (ethyl acetate-hexane).

45 Example 17

1- (3-mercaptopropanoyl) -L-proline tert-butyl ester

1.76 g of propiothiolactone are added to a solution of 3.42 g of L-proline t-butyl ester in 10 ml of dry tetrahydrofuran refrigerated in an ice bath. After storing for 5 min in the ice bath and 3 h at room temperature, the reaction mixture is diluted with 200 ml of ethyl acetate and washed with 5% potassium bisulfate and then water. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue 55, that is to say the 1- (3-mercaptopropanoyl) -L-proline t-butylester, is crystallized from ether-hexane and 3.7 g are obtained which melt at 57- 58 ° C.

Example 18 M 1- (3-mercaptopropanoylj-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 kept with stirring under argon „5 for 1 h. The reaction mixture is diluted with water, filtered and the filtrate is extracted with ethyl acetate. The aqueous phase is acidified with concentrated hydrochloric acid, saturated with sodium chloride and extracted with acetate

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ethyl. The organic layers are washed with saturated sodium chloride, dried over magnesium sulfate and concentrated to dryness in vacuo. The residue is crystallized, that is to say l- (3-mercaptopropanoyl) -L-proline from ethyl acetate and hexane and 2.5 g are obtained which melt at 68- 70 ° C.

Method B

0.8 g of 1- (3-acetylthiopropanoyl) -L-proIine is dissolved in 5 ml of 5.5N methanolic ammonia and the solution is kept under argon at room temperature. After 2 h, the solvent is removed under vacuum, the residue is dissolved in water and it is applied to an ion exchange column on the H + cycle (“Dowex 50”, analytical quality) and it is eluted with some water. The fractions which give a positive thiol reaction are combined and concentrated to dryness to obtain 0.6 g. This product is crystallized from ethyl acetate-hexane as in process A to obtain l- (3-mercaptopropanoyl) -L-proline.

Method C

2.3 g of 1- (3-mercaptopropa-nucleus) -L-proline t-butyl ester are dissolved in a mixture of 20 ml of anisole and 45 ml of trifluoroacetic acid. After having kept for 1 h at room temperature under argon, the reaction mixture is concentrated to dryness under vacuum and the residue is precipitated from ethyl acetate-hexane several times. The 1.9 g of residue are dissolved in 30 ml of ethyl acetate and 1.85 ml of dicyclohexylamine are added. The crystalline salt is filtered and recrystallized from isopropanol to obtain 2 g which melts at 187-188 ° C.

The salt is converted to the acid as in Example 1 and 1.3 g are obtained. The product is crystallized from ethyl acetate-hexane as in process A.

Salts:

sodium

500 mg of l- (3-mercaptopropanoyl) -L-proline are dissolved in a mixture of 2.5 ml of water and 2.5 ml of sodium hydroxide N. The solution is lyophilized to obtain 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 with gentle heating until completely dissolved. Then the solvent is removed by lyophilization to obtain the magnesium salt. calcium

500 mg of 1- (3-mercaptopropanoyl) -2-proline are dissolved in a mixture of 91 mg of calcium hydroxide and 10 ml of water, then the solution is lyophilized to obtain the calcium salt.

potassium

500 mg of 1- (3-mercaptopropanoyl) -L-proline are dissolved in a mixture of 246 mg of potassium bicarbonate and 10 ml of water and lyophilized to obtain the potassium salt.

N-methyl-D-glucamine

500 mg of 1- (3-mercaptopropanoyl) -L-proline and 480 mg of N-methyl-D-glucamine are dissolved in 10 ml of water and lyophilized to obtain the N-methyl-D-glucamine salt.

Example 19

1 - (3-mercaptopropanoyl) -L-hydroxyproline

By substituting L-hydroxyproline for L-proline in the method of Example 11 and then treating the product by Method A of Example 18, we obtain l- (3-benzoylthiopro-panoyl) -L-hydroxyproline and 1- (3-mercaptopropanoyl) -L-hydroxyproline respectively.

Example 20

1- (3-mercaptopropanoyl) -L-azetidine-2-carboxylic acid

By substituting the t-butyl ester of L-azetidine-2-car-

boxylic (prepared by substitution of proline in L-azetidine-2-carboxylic acid in Example 14) for L-proline t-butylester in the process of Example 15, treating the product as in Example 16 and l- (3-acetylthiopropanoyl) -L-azetidine-2-carboxylic acid thus obtained by method B of Example 18, the t- butyl ester of l- (3-acetylthio-propanoyl acid) is obtained ) -L-azetidine-2-carboxylic acid and l- (3-mercap-topropanoyl) -L-azetidine-2-carboxylic acid respectively.

Example 21

L- (3-mercaptopropanoyl) -L-pipecolic acid

By substituting the t-butyl ester of L-pipecolic acid (prepared by substituting L-pipecolic acid for L-proline in Example 14) for the t-butyl ester of L-proline in the process of Example 15 and by treating the product by method C of Example 18, the t- butyl ester of l- (3-mercapto-propanoyl) -L-pipecolic acid and l- (3-mercaptopropanoyl) -L- are obtained. pipecolic respectively.

Example 22 l- (3-mercaptopropanoyl) -4-methyl-L-proline

By substituting 4-methyl-L-proline for L-proline in the method of Example 13 and then treating the product by Method A of Example 18, we obtain l- (3-benzoylthiopro-panoyl) -4-methyl-L-proline and 1- (3-mercaptopropanoyl) -4-methyl-L-proline.

Example 23

Acid 1 - (3-mercaptopropanoyl) -5-hydroxy-L-pipecolic

By substituting 5-hydroxy-L-pipecolic acid for L-proline in the method of Example 13 and then treating the product by Method A of Example 18, we obtain the acid l- (3- benzoylthiopropanoyI) -5-hydroxy-L-pipecolic and l- (3-mercaptopropanoyl) -5-hydroxy-L-pipecolic acid.

Example 24 l- (3-mercaptopropanoyl) -D-proline

By substituting D-proline for L-proline in the method of Example 13 and then treating the product by Method A of Example 18, we obtain the l- (3-benzoylthiopropanoyl) -D-pro-line and 1- (3-mercaptopropanoyl) -D-pro! ine which melts at 68-70 ° C.

EXAMPLE 25 3-acetylthio-2-methylpropanoic acid

Heated in a water bath for 1 h a mixture of 50 g of thio-acetic acid and 40.7 g of methacrylic acid and then kept at room temperature for 18 h. After confirming by NMR spectroscopy that the complete reaction of methacrylic acid has taken place, the reaction mixture is distilled in vacuo and the desired 3-acetylthio-2-methylpropanoic acid is separated in the boiling fraction at 128.5 -131 ° C / 2.6 mm Hg; the yield is 64 g.

Example 26 3-Benzoylthio-2-methylpropanoic acid

By substituting thiobenzoic acid for thioacetic acid in the process of Example 25, 3-benzoyl-thio-2-methylpropanoic acid is obtained.

Example 27 3-Phenylacetylthio-2-methylpropanoic acid

By substituting thiophenylacetic acid for thioacetic acid in the process of Example 25, 3-phenylacetylthio-2-methylpropanoic acid is obtained.

Example 28

tert-butylester del- (3-acetylthio-2-methylpropanoyl) -L-proline 5.1 g of L-proline t-butylester are dissolved in 40 ml of

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dichloromethane and the solution is stirred and refrigerated in an ice bath. 6.2 g of dicyclohexylcarbodiimide dissolved in 15 ml of dichloromethane are added, then a solution of 4.9 g of 3-acetylthio-2-methylpro-panoic acid in 5 ml of dichloromethane is immediately added. After having been stirred for 15 min in the ice bath and 16 h at room temperature, the precipitate is separated by filtration and the filtrate is concentrated to dryness under vacuum. The residue is dissolved in ethyl acetate and washed until neutral. The organic phase is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue, i.e. the 1- (3-acetylthio-2-methylpropanoyl) -L-proline t-butyl ester, is purified by column chromatography (silica gel-chloroform) and 7.9 g are obtained.

Example 29 15

l- (3-acetylthio-2-methylpropanoyl) -L-proline Method A

7.8 g of 1- (3-acetylthio-2-me-thylpropanoyl) -L-proline t-butyl ester of Example 28 are dissolved in a mixture of 55 ml of anisole and 110 ml of trifluoro- acetic. After keeping for 1 hour at room temperature, the solvent is removed in vacuo and the residue is precipitated several times from ether-hexane. The 6.8 g of residue are dissolved in 40 ml of acetonitrile and 4.5 ml of dicyclohexylamine are added. The crystalline salt is boiled with 100 ml of fresh acetonitrile, 25

refrigerate to room temperature and filter to obtain 3.8 g which melts (165) at 187-188 ° C. This substance is recrystallized from isopropanol. It has a value [a] D = —67 ° (Cl, 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 concentrated to dryness. The residue is crystallized from ethyl acetate-hexane to obtain l- (3-acetyl-thio-2-D-methylpropanoyl) -L-proIine which melts at 83-85 ° C and has

25 35

a value [a] ^ = —162 (c, 1.7, EtOH).

Method B

8.1 g of 3-acetylthio-2-methylpropanoic acid and 7 g of thionyl chloride are mixed, then the suspension 40 is stirred for 16 h at ordinary temperature. The reaction mixture is concentrated to dryness and distilled under vacuum (m.p. = 80 ° C). 5.4 g of this 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 sodium hydroxide. normal refrigerated in an ice water bath. After stirring for 3 h at room temperature, the mixture is extracted with ether, the aqueous phase is acidified and extracted with ethyl acetate. The organic phase is dried over magnesium sulfate and concentrated to dryness to obtain 1- (3-50

acetylthio-2-DL-methylpropanoyl) -L-proline.

Method C

4.16 g of methacryloyl chloride are added to a solution of 3.45 g of L-proline in a mixture of 100 ml of water and 12 g of sodium bicarbonate chilled in an ice and water bath. shaking vigorously. When the addition is complete, the mixture is stirred at room temperature for 2 h and then extracted with ether. The aqueous phase is acidified with N hydrochloric acid and extracted with ethyl acetate. The organic phase is concentrated to dryness under vacuum, 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 water bath for 2 h. The reaction mixture is dissolved in a 75:25 mixture of benzene-acetic acid and applied to a column of silica gel. Elution with the same solvent mixture gives 1- (3-acetylthio-2-DL-methylpro-panoyl) -L-proline.

Example 30

1- (3-Benzoylthio-2-methylpropanoyl) -L-pro-line tert-butyl ester

By substituting 3-benzoylthio-2-methylpropanoic acid for 3-acetylthio-2-methylpropanoic acid in the process of Example 28, the t- (3-benzoylthio-2-methylpropanoyl) t-butylester is obtained -L-proline.

Example 31

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

By substituting 3-phenylacetylthio-2-methylpropanoic acid for 3-acety-2-methylpropanoic acid in the process of Example 28, the t- (3-phe-nylacetylthio) t-butylester is obtained. 2-methylpropanoyl) -L-proline.

Example 32

l- (3-benzoylthio-2-methylpropanoyl) -L-proline

By substituting 1- (3-benzoylthio-2-me-thylpropanoyI) -L-proIine t-butyl ester for 1- (3-acetyl-2-methylpropanoyl) -L-proline t-butyl ester in process A of l Example 29, l- (3-benzoylthio-2-methylpropanoyl) -L-proline is obtained.

Example 33

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

By substituting 1- (3-phenylacetylthio-2-methylpropanoyl) -L-proline t-butyl ester for 1- (3-acetylthio-) t-butyl ester

2-methylpropanoyl) -L-proline in process A of Example 29, 1- (3-phenylacetylthio-2-methylpropanoyl) -L-proline is obtained.

Example 34

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 29, 32 and 33 as follows:

0.85 g of the thioester is dissolved in 5.5N methanolic ammonia and the solution is kept at room temperature for 2 h. The solvent is removed in vacuo and the residue is dissolved in water, applied to an ion exchange column on the H + cycle ("Dowex 50", analytical grade) and eluted with water. The fractions which give a positive thiol reaction are combined and lyophilized. The residue is crystallized from ethyl acetate-hexane and 0.3 g is obtained. 1- (3-mercapto-2-D-methylpropanoyl) -L-proline melts at 103-104 ° C and has a value [a] D = —131 (C, 2, EtOH).

Example 3 5

1- (3-acetylthio-2-methylpropanoyl) -L-proline methyl ester

The 1- (3-acetylthio-2-methylpropanoyl) -L-pro-line is reacted with an ethereal solution of diazomethane according to the process described in Example 3 to obtain the methyl ester of 1- (3-acetylthio-2- methylpropanoyl) -L-proline.

Example 36

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

By substituting the methyl ester of 1- (3-acetylthio-2-methyl-propanoyl) -L-proline in the process of Example 4, the amide of 1- (3-mercapto-2-methylpropanoyl) -L is obtained. -proline.

EXAMPLE 37 3-Acetylthio-2-Benzylpropanoic Acid

By substituting 2-benzylacrylic acid for methacrylic acid in the process of Example 25, 3-acé-tylthio-2-benzylpropanoic acid is obtained.

Example 38

1- (3-acetylthio-2-benzylpropanoyl) -L-proline tert-butyl ester By substituting 3-acetylthio-2-benzylpropanoic acid for

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3-acetylthio-2-methylpropanoic acid in the process of Example 22, the t-butyl ester of l- (3-acetylthio-2-benzylpropanoyI) -L-proline is obtained.

Example 39 1- (3-acetylthio-2-benzylpropanoyl) -L-proline

The product of Example 38 is substituted for the 1- (3-acetylthio-2-methylpropanoyl) -L-proline t-butyl ester in Method A of Example 29 to obtain 1- (3-acetylthio-2- benzylpro-panoyl) -L-proline.

Example 40 l- (3-mercapto-2-benzylpropanoyl) -L-proline

The l- (3-acetylthio-2-benzylpropanoyl) -L-proline is treated with methanolic ammonia according to the method of Example 34 to obtain l- (3-mercapto-2-benzylpropanoyi) -L-pro- line in the form of an oil which has an Rf value = 0.47 (silica gel, 75:25 mixture of benzene-acetic acid).

Example 41

l- (3-mercapto-2-methylpropanoyl) -L-hydroxyproline

By substituting the t-butyl ester t-butyl ether of L-hydroxyproline in the method of Example 28, by treating the product according to Method A of Example 29 and then continuing as in Example 34, the t- is obtained. 1- (3-acetylthio-2-methylpropanoyl) -L-hydroxyproline butyl ester, 1- (3-acetylthio-2-methylpropanoyl) -L-hydroxyproline t-butyl ether and l- (3-mercapto-2-methylpropanoyl ) -L-hydroxyproline respectively.

Example 42

1- (3-mercapto-2-methylpropanoyl) -L-azetidine-2-carboxylic acid

By substituting the t-butyl ester of L-azetidine-2-carboxylic acid in the process of example 28, by treating the product according to process A of example 29 and then continuing as in example 34, the t- butyl ester of l- (3-acetylthio-2-methylpropanoyl) -L-azetidine-2-carboxylic acid, 1,3-acetylthio-2-methylpropanoyl) -L-azetidine-2-carboxy is obtained -lique and l- (3-mercapto-2-methylpropanoyl) -L-azéti-dine-2-carboxyIique acid.

Example 43

1- (3-mercapto-2-methylpropanoyl) -L-pipecolic acid

By substituting L-pipecolic acid in the method of Example 28, by treating the product according to Method A of Example 29 and then continuing as in Example 34, the acid t-butyl ester is obtained. - (3-acetylthio-2-methyl! Propa-nucleus) -L-pipecolic acid l- (3-acetylthio-2-methylpropa-nucleus) -L-pipecolic acid l- (3-mercapto- 2-methylpropa-noyl) -L-pipecolic respectively.

Example 44

l- (4-benzoylthiobutanoyl) -L-proline

To a solution of 2.88 g of L-proline in 25 ml of normal sodium hydroxide refrigerated in an ice bath, 12.5 ml of 2N sodium hydroxide and 3.5 g of 4- chloride are added. chlorobutyryia. The reaction mixture is stirred at room temperature for 3.5 h and a suspension of 3.75 g of thiobenzoic acid and 2.4 g of potassium carbonate in 25 ml of water is added. After stirring overnight at room temperature, the reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue is chromatographed on a silica gel column with a 7: 1 mixture of benzene: acetic acid. The fractions containing the desired substance are combined and concentrated to dryness to obtain 1.35 g.

A small aliquot of this substance is dissolved in ethyl acetate and dicyclohexylamine is added until pH = 8-10 (on wet paper at pH). The dicyclohexylamine salt separates by crystallization immediately. It melts at 159-161 ° C.

Example 45 l- (4-mercaptobutanoyl) -L-proline

1.08 g of 1- (4-benzoylthiobutanoyl) -L-proline are dissolved in a mixture of 4 ml of water and 2.7 ml of concentrated ammonia. After stirring for 1 hour at room temperature, the mixture is diluted with water, filtered, extracted with ethyl acetate and the aqueous phase is concentrated in vacuo. This ammonium salt of 1- (4-mercaptobutanoyl) -L-proline is purified by ion exchange chromatography on a column of diethylaminoethyl- "Sephadex" (crosslinked dextran) with a gradient of ammonium bicarbonate; 0.7 g is obtained. Dissolve the ammonium salt in 2 ml of water and apply it to a column of sulfonic acid resin - "Dowex 50" of analytical quality in H + form and elute the free acid with water. . The fractions containing the desired substance (positive towards the sulfhydryl reagent and the carboxyl reagent) are combined and lyophilized to obtain l- (4-mercaptobutanoyl) -L-proline. The dicyclohexylammonium salt is prepared by the method of Example 44; it melts at 157-158 ° C.

Example 46 4-Bromo-2-methylbutanoic acid

1.04 g of ethyl 4-bromo-2-methylbutanoate (G. Jones and J. Wood, "Tetrahedron", 21.2961 (1965)) are dissolved in 50 ml of dichloromethane and the mixture is cooled to -10 ° C. A 1M solution of boron tribromide in dichloromethane (50 ml) is added dropwise with stirring and the stirring is continued for 1 h - 10 ° C 2 h at 25 ° C. The reaction is terminated by carefully adding water . The layers are separated and the organic phase is washed with water, dried and concentrated to dryness to obtain 4-bromo-2-methylbutanoic acid.

Example 47 l- (4-benzoylthio-2-methylbutanoyl) -L-proline a) 8 g of 4-bromo-2-methylbutanoic acid and 7 g of thionyl chloride are mixed and the mixture is stirred for 16 h at ordinary temperature. The reaction mixture is concentrated to dryness and distilled in vacuo.

b) To a solution of 2.88 g of L-proline in 25 ml of normal sodium hydroxide refrigerated in an ice bath, 12.5 ml of 2N sodium hydroxide and 3.9 g of chloride D are added. 4-bromo-2-methylbutanoic acid obtained in step a). The reaction mixture is stirred at room temperature for 3.5 h and a suspension of 3.75 g of thiobenzoic acid and 2.4 g of potassium carbonate in 25 ml of water is added. After stirring overnight at room temperature, the mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue is chromatographed on a silica gel column with a 7: 1 mixture of benzene: acetic acid. The fractions containing the desired product, that is to say l- (4-benzoylthio-2-methylbutanoyl) -L-proline, are combined and concentrated to dryness under vacuum.

Example 48 l- (4-mercapto-2-methylbutanoyl) -L-proline

By substituting l- (4-benzoylthio-2-methylbutanoyl) -L-proline for l- (4-benzoylthiobutanoyl) -L-proline in the process of Example 45, l- (4-mercapto- 2-methylbu-tanoyl) -L-proline.

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Example 49 A 4-bromo-2-benzylbutanoic acid

By substituting ethyl 4-bromo-2-benzylbutanoate (prepared by the method of G. Jones and J. Wood "Tetrahedron", 21, 2961 (1965), starting from diethyl benzylmalonate) for 5 4-bromo- Ethyl 2-methylbutanoate in the process of Example 46, 4-bromo-2-benzylbutanoic acid is obtained.

Example 50

l- (4-benzoylthio-2-benzylbutanoyl) -L-proline m

By substituting 4-bromo-2-benzylbutanoic acid for 4-bromo-2-methylbutanoic acid in the process of Example 47, we obtain l- (4-benzoylthio-2-benzylbutanoyl) -L-pro -line.

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Example 51 l- (4-mercapto-2-benzylbutanoyl) -L-proline

By substituting l- (4-benzoylthio-2-benzylbutanoyl) -L-proline for l- (4-benzoy! Thiobutanoyl) -L-proline in the process of Example 45, l- (4- mercapto-2-benzylbutanoyl) -L-proline.

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Example 52 l- (4-mercaptobutanoyl) -L-hydroxyproline

By substituting L-hydroxyproline for L-proline in the process of Example 44 and subjecting the product to ammonolysis as in Example 45, there is obtained l- (4-benzoylthiobutanoyI) -L-hydroxyproline and 1- (4-mercaptobu-tanoyl) -L-hydroxyproline respectively.

Example 53

1- (4-mercaptobutanoyl) -L-azetidine-2-carboxylic acid By substituting L-azetidine-2-carboxylic acid for L-proline in the process of Example 44 and subjecting the product to ammonolysis as in example 45, l- (4-benzoylthiobutanoyl) -L-azetidine-2-carboxy-lique acid and l- (4-mercaptobutanoyl) -L-azetidine-2-carboxy-lique acid are obtained respectively .

Example 54 A cide l- (4-mercaptobutanoyl) -L-pipecolic

By substituting L-pipecolic acid for L-proline in the process of Example 44 and subjecting the product to ammonolysis as in Example 45, we obtain l- (4-benzoylthiobutanoyl) -L acid -pipecolic and l- (4-mercapto-butanoyl) -L-pipecolic acid respectively.

Example 55

1- (3-acetylthiobutanoyl) -L-proline tert-butyl ester 50

6.2 g of dicyclohexylcarbodi-imide and 4.86 g of 3-acetylthiobutyric acid are added to a solution of 5.1 g of L-proline t-butyl ester in 60 ml of dichloromethane stirred in an ice bath. After 15 min, the ice bath is removed and the mixture is stirred at room temperature for 16 h. The precipitate is filtered, the filtrate is concentrated to dryness and the residue is chromatographed on a silica gel column with chloroform to obtain 5.2 g of 1- (3-acetylthiobutanoyl) -L-proline t-butylester.

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Example 56 l- (3-acetylthiobutanoyl) -L-proline

The 5.2 g of 1- (3-acetylthiobuta-nucleus) -L-proline t-butyl ester of Example 55 are dissolved in a mixture of 60 ml of trifluoroacetic acid and 30 ml of anisole and the ,,,

solution at room temperature for 1 h. The solvents are separated under vacuum and the residual 1- (3-acetylthiobutanoyl) -L-proIine is reprecipitated from ether-hexane several times to obtain 4 g. The dicyclohexylamine salt is prepared by the method of Example 44, it melts at 175-176 ° C.

Example 57 1 - (3-mercaptobutanoyl) -L -proline

0.86 g of the 1- (3-acetylthiobutanoyl) -L-proline of Example 56 is dissolved in 20 ml of 5.5N methanolic ammonia and the reaction mixture is kept at room temperature for 2 h. The solvent is removed in vacuo and the residue is chromatographed on an ion exchange column (Dowex 50) with water. The fractions containing the desired 1- (3-mercap-tobutanoyl) -L-proline are combined and lyophilized to give 0.6 g. The dicyclohexylamine salt is prepared by the method of Example 44, it melts at 183-184 ° C.

Example 58

l- [3 - [[(ethoxy) carbonyl] thio] propanoyl] -L-proline

1.2 g of ethyl chloroformate are added to a solution of 2.03 g of 3-mercaptopropanoyl-L-proline in 30 ml of normal sodium bicarbonate and the mixture is vigorously stirred at 5 ° C. for 1 h and then for 2 h at room temperature. After acidification with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic phase is washed with water, dried over magnesium sulfate and concentrated to dryness to obtain l- [3 - [[(ethoxy) -carbonyl] thio] -propanoyl] -L-proline.

Example 59

l- [3 - [[(ethoxy) thiocarbonyl] thio] propanoyl] -L-proline

25 ml of 2N aqueous 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 sodium hydroxide N which is refrigerated and stirred in a ice. After 5 min, the ice bath is removed and the stirring is continued at room temperature. After 3 h, 9.6 g of potassium salt of ethylxantogenic acid are 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 concentrated to dryness under vacuum and the residue is chromatographed on a silica gel column with a 7: 1 mixture of benzene-acetic acid as solvent to obtain l- [3 ~ [[(ethoxy) thiocar-bonyI] thio ] propanoyl] -L-proline which melts at 94-95 ° C.

Example 60

l- [3 - [[(benzylthio) carbonyl] thio] propanyol] -L-proline

A solution of 11 ml of benzylthio-carbonyl chloride in 20 ml of dioxane in five portions is added to a solution of 1.6 g of l- (3-mercaptopropanoyl) -L-proline in 24 ml of refrigerated normal sodium bicarbonate in an ice bath for 30 min. The ice bath is removed and stirring is continued for 2.5 h at room temperature. After acidification with concentrated hydrochloric acid, the aqueous phase is extracted with ethyl acetate. The organic phase is dried over magnesium sulfate and concentrated to dryness to obtain l- [3 - [[(benzylthio) carbonyl] thio] propanoyl] -L-proline.

Example 61

l- [3 - [[(ethylthio) thiocarbonyl] thio] propanoyl] -L-proline

25 ml of 2N aqueous 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 sodium hydroxide N which is refrigerated and stirred in a ice. After 5 min, the ice bath is removed and the stirring is continued at room temperature. After 3 h, 10.5 g of potassium salt of ethyltrithiocarbonate are added and the mixture is stirred at room temperature overnight. After acidification with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. We dry the diaper

622 503

14

organic on magnesium sulfate and concentrated to dry proline with 3-mercaptopropanoyl-L-proline in the process for obtaining l- [3 - [[- ethylthiothiocarbonyl] -thio] propanoyl] - Example 58, l- [3 - [[(ethoxy) carbonyl] thio] -2-me-L-proIine is obtained. thylpropanoyl] -L-proline.

Example 62 „Example 67

3-ff (methylamino) thiocarbonyl] thio] propionic acid l- [3 - [[(ethoxy) carbonyl] thio] butanoyl] -L-proline

4 g of methyl isothiocyanate are added to a solution of En substituting l- (3-mercaptobutanoyl) -L-proline for 5.3 g of 3-mercaptopropionic acid in a mixture of 250 3-mercaptopropanoyl-L-proline in the method of Example ml of Pyridine and 100 ml of 0.5N sodium hydroxide. We keep gg ^ we obtain the l- [3 - [[(ethoxy) carbonyl] thio] butanoyl] -the solution at 40 ° C for 2 h then concentrated to dryness under] () L-proline empty. The residue is dissolved in 100 ml of water, acidified with concentrated hydrochloric acid and extracted with ether. On Example 68

dry concentrates the organic phase to obtain the 3 - [[(me- Acid 1 - [3 - [[(ethoxy) thiocarbonyl] thio] propanoyl] -L-azetidine-thylamino) thiocarbonyl] thio] propionic acid 86-87 ° C. 2-carboxylic

By substituting L-azetidine-2-carboxylic acid for Example 63 L-proline in the process of Example 59, the tert-butyl ester of 1 - [3 - [[((methylamino) thiocarbonyl] thio)] is obtained ] -pro- l- [3 - [[(ethoxy) thiocarbonyl] thio] propanoyl] -L-azetidine-2-car-panoyl] -L-proline boxylic.

To a solution of 1.71 g of L-proline t-butyl ester and 1.35 g of hydroxybenzotriazole in 10 ml of dichloromethane (Example 69)

managed and stirred in an ice bath, 2.06 g of Acid 1 ~ [3 - [[(ethoxy) thiocarbonyl] thio] propanoyl] -L-pipecoli-

dicyclohexylcarbodi-imide and 1.79 g of 3-methylaminothioic carbonylthiopropionic acid. After 15 min, the bath is removed and the L-pipecolic acid is substituted for L-proline in the stirring process, overnight. The precipitate is separated by the method of Example 59, the acid 1- [3 - [[(ethoxy) thio-filtration is obtained and the filtrate is diluted with ethyl acetate and carbonyl] thio ] propanoyl] -L-pipecolic.

wash until neutral. The organic phase is concentrated to dryness to obtain the t-butyl ester of 1 - [3 - [[(methylamino) -thiocarbo- Example 70

nyl] thio] propanoyI] -L-proline which melts at 129-130 ° C. l- [4 - [[(benzylthio) carbonyl] thio] butanoyl] -L-proline

By substituting 4-mercaptobutanoyl-L-proline for 3-mer-Example 64 30 captopropanoyl-L-proline in the process of Example 60, 1- [3 - [[(methylamino) thiocarbonyl] thio] propanoyl] -L-proline obtains l- [4 - [[(benzylthio) carbonyl] thio] butanoyl] -L-proline.

A) 0.98 g of 1- (methylamino-thiocarbonylthiopropanoyl) -L-proline t-butylester are dissolved in a mixture of 3.6 g Example 71

anisole and 7.5 ml of trifluoroacetic acid. After 1 h at 1-ß'll (benzylthio) carbonyl] thio] propanoyl] -L-proline at room temperature, the mixture is concentrated to dryness under vacuum under substitution of the 2-mercaptopropanoyl-L-proline and the precipitate the residue from ether-hexane three times. 3-Mercaptopropanoyl-L-proline in the process of the example Chromatography this substance on a column of silica gel 60, we obtain l- [2 - [[(benzylthio) carbonyl] thio] propanoyl] -with a mixture 75: 25 of benzene: acetic acid like L-proline.

solvent to obtain l- [3 - [[(methylamino) thiocarbonyl] thio] - Example 72

propanoyl] -L-proline which has an Rf value = 0.4 (silica gel 40- [3 - [[(ethylthio) thiocarbonyl] thio] propanoyl] -benzene methyl ester: benzene: acetic acid (75:25)). The dicyclohexylammo- L-proline nium salt melts at 127-129 ° C. A solution of l- [3 - [[(ethylthio) thiocarbonyl] -

B) 4 g of methyl isothiocyanate are added to a thio] propanoyl] -L-proline solution in ethyl acetate with a solution of 10.1 g of 3-mercaptopropanoyl-L-proline in a mixture. ethereal diazomethane until a color of 250 ml of pyridine and 100 ml of 0.5N sodium hydroxide is obtained. 45 persistent yellow. After destroying the color yellow with

The solution is kept at 40 ° C for 2 h and concentrated to dry a few drops of acetic acid, the solvents are separated under vacuum. The residue is dissolved in 100 ml of water, it is acidified empty to obtain the methyl ester of 1- [3 - [[(ethylthio) thiocarbo-with concentrated hydrochloric acid and it is extracted with acetate nyl ] thio] propanoyl] -L-proline.

ethyl. The organic phase is concentrated to dryness to obtain l- [3 - [[(methyIamino) thiocarbonyI] thio] propanoyl] -L-proline. 50 Example 73

Acid 1 - [3 - [[(methylamino) thiocarbonyl] thio] propanoyl] -5-hy-Example 65 droxy-L-pioecolic l- [3 - [[(ethylamino) carbonyl] thio] propanoyl] -L-proline En substituting 1- [3-mercaptopropanoyl) -5-hydroxy- acid

0.45 ml of ethyl isocyanate is added to a solution of L-pipecolic with 3-mercaptopropanoyl-L-proline in pro-1 g of 1- (3-mercaptopropanoyl) -L-proline in a mixture of 55 yielded B of Example 64, we obtain the acid l- [3 - [[(methylami-5 ml of sodium hydroxide N and 5 ml of pyridine. No heating) thiocarbonyl] thio] propanoyl] -5 -hydroxy-L-pipecolic. the solution at 40 ° C for 4 h and concentrated in vacuo. The residue is distributed between 0, IN hydrochloric acid and Example 74

ethyl acetate. The organic layer is washed with water, it is amide from 1- [3 - [[(methylamino) thiocarbonyl] thio] -2-methylpro-dry over magnesium sulfate and it is concentrated to dryness for 60 panoyl] - L-proline obtain l- [3 - [[(ethylamino) carbonyl] thio] propanoyl] -L-pro- By substituting the amide of l- (3-mercapto-2-methylpropa-

line. The dicyclohexylammonium salt is prepared by adding the nucleus) -L-proline to 3-mercaptopropanoyl-L-proline in dicyclohexylamine to a solution of the free acid in the acetate process B of Example 64, amide of 1- [3 - [[(methyl; it melts at 150-152 ° C. thylamino) thiocarbonyl] thio] -2-methylpropanoyl] -L-proline.

65

Example 66 Example 75

l-13 - [[(ethoxy) carbonyl] thio] -2-methylpropanoyl] -L-proline l- [3 - [[(phenoxy) carbonyl] thio] propanoyl] -L-proline

By substituting 1- (3-mercapto-2-methylpropanoyl) -L- By substituting phenyl chloroformate for chlorofor-

15

622 503

ethyl miate in the process of Example 58, l- [3 - [[(phenoxy) carbonyl] thio] propanoyl] -L-proline is obtained.

Example 76

l- [3 - [[(phenoxy) carbonyl] thio] butanoyl] -L-proline?

By substituting phenyl chloroformate for ethyl chloroformate and 4-mercaptobutanoyl-L-proline for 3-mer-captopropanoyl-L-proline in the process of Example 58, l- [3- [[(phenoxy) carbonyl] thio] butanoyl] -L-proIine.

Example 77

l- [3 - [[(phenylamino) carbonyl] thio] propanoyl] -L-proline

By substituting phenyl isocyanate for ethyl isocyanate in the process of Example 65, l- [3 - [[(phenylamino) carbonyl] thio] propanoyl] -L-proline is obtained. 5

Example 78

l- [3 - [[(phenethylamino) carbonyl] thio] propanoyl] -L-proline

By substituting phenethyl isocyanate for ethyl isocyanate in the process of Example 65, l- [3- 1 () [[(phenethylamino) carbonyl] thio] propanoyl] -L-proline is obtained.

Example 79

l- [3 - [[(ethylamino) carbonyl] thio] -2-benzylpropanoyl] -L-pro-line 25

By substituting l- (3-mercapto-2-benzyIpropanoyl) -L-proline for l- (3-mercaptopropanoyl) -L-proIine in the process of Example 65, l- [3 - [[ (ethylamino) carbonyl] -thio] -2-benzylpropanoyl] -L-proline.

30

Example 80

l - (3-methylthiopropanoyl) -L-proline

A) 51 g of methyl 3-methylthiopropionate are saponified with 150 ml of a 10% sodium hydroxide solution

for 30 min at 100 ° C. The cooled solution is extracted with ether and then acidified. The crude acid thus obtained is distilled and converted to acid chloride with thionyl chloride.

A solution of 11.5 g of L-proline in 100 ml of sodium hydroxide N is refrigerated in an ice bath and 6.9 g of 3-methylthiopropanoic acid chloride is added dropwise to 40 drops with vigorous stirring. 10 min lesson. After 5 h the reaction mixture is acidified and extracted with ethyl ether to obtain l- (3-methylthiopropanoyl) -L-proline. The dicyclohexylammonium salt is prepared by adding the dicyclohexylamine to a solution of the free acid in ethyl acetate; it melts at 169-171 ° C.

B) 71 g of methyl iodide are added to a solution of 115 g of 1- (3-mercaptopropanoyl) -L-proline ethylester and 11.5 g of sodium in 400 ml of ethanol. The reaction is allowed to continue overnight, the ethanol is removed in vacuo and the residue is dissolved in a mixture of ethyl acetate and water.

The organic layer is dried and concentrated to dryness under vacuum. The 98 g of 1- (3-methylthio-propanoyl) -L-proline ethylester obtained are suspended in a mixture of 200 ml of methanol and 200 ml of 5N sodium hydroxide and the mixture is stirred at room temperature for 5 h. The methanol is separated under vacuum and the aqueous phase is extracted with ethyl acetate, it is acidified and it is re-extracted with ethyl acetate. This last organic phase is washed with water, dried and concentrated to dryness to obtain l- (3-methylthiopropanoyl) -L-proline. 60

Example 81

l- [3- (4-chlorophenylthio) propanoyl) -L-proline

25 ml of 2N aqueous sodium hydroxide and 8.5 g 65 of 3-bromopropionyl chloride are added to a solution of 5.75 g of L-proline in 50 ml of sodium hydroxide N, refrigerated and stirred in an ice bath. After 5 min, the ice bath is removed and the stirring is continued for 3 h at ordinary temperature. The reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness in vacuo. The residue is dissolved in a mixture of 8 g of 4-chlorobenzenethiol, 4.2 g of sodium hydroxide and 300 ml of ethanol. The solution is heated at reflux for 6 h. The solvent is removed in vacuo and the residue is dissolved in water, acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness in vacuo to give l- [3- (4-chlorophenylthio) propanoyl] -L-proline.

Example 82

l - [[(3-benzylthiomethyl) thio] propanoyl] -L-proline

8.1 g of l- (3-mercaptopropanoyl) -L-proline are dissolved in 100 ml of boiling liquid ammonia and small pieces of sodium are added until a persistent blue color is obtained which is destroyed then with a small piece of ammonium chloride. 6.9 g of benzyl thiomethyl chloride are added and the ammonia is allowed to evaporate. The last traces of ammonia are separated under vacuum, the residue is dissolved in water and extracted with ethyl acetate. The aqueous phase is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness to obtain l - [[(3-benzyl-thiomethyI) thio] propanoyl] -L-proline.

Example 83

l - [[(3-acetamidomethyl) thio] propanoyl] -L-proline

2 g of 1- (3-mercaptopropanoyl) -L-proline and 0.89 g of N-hydroxymethylacetamide are dissolved in 10 ml of trifluoroacetic acid and the solution is kept at ordinary temperature for 1 h. The excess trifluoro-roacetic acid is separated under vacuum and the residue is precipitated several times from e-ther-hexane. Finally, the residue is distributed between dilute hydrochloric acid and ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness to obtain l - [[(3-acetamidomethyl) thio] propanoyl] -L-proline.

Example 84 l- (methylthio-acetyl) -L-proline

By substituting methyl methyl thioacetate for methyl 3-methylthiopropionate in process A of Example 80, one obtains l- (methylthio-acetyl) -L-proline which melts at 123-124 ° C.

Example 85 1 - (benzylthio-acetyl) -L-proline

By substituting benzylthio-acetyl chloride for 3-methylthiopropanoyl chloride in process A of Example 80, one obtains l- (benzylthio-acetyl) -L-proline which melts at 86-88 ° C.

Example 86

l- [3 - [(2-phenylethyl) thio] propanoyl] -L-proline

By substituting phenethyl bromide for methyl iodide in process B of Example 80, l- [3 - [(2-phenylethyl) thio] propanoyl] -L-proline is obtained.

Example 87

l- [3 - [(triphenylmethyl) thio] propanoyl] -L-proline

By substituting triphenylmethyl chloride for methyl iodide in process B of Example 80, l- [3 - [(triphenylmethyl) thio] propanoyl] -L-proline is obtained.

Example 88

1- (3-methylthio-2-methylpropanoyl) -L-proline amide By substituting 1- (3-mercapto-2-methylpropa-) amide

622 503

16

nuclei) -L-proline to the ethyl ester of 1- (3-mercaptopropanoyl) -L-proline in process B of Example 80 and eliminating the saponification step, the amide of 1- (3-methyl) is obtained -thio-2-methylpropanoyl) -L-proline.

Example 89

1 - (3-methylthiopropanoyl) -L-azetidine-2-carboxylic acid

By substituting L-azetidine-2-carboxylic acid for L-proline in process A of Example 80, we obtain l- (3-methylthiopropanoyl) -L-azetidine-2-carboxylic acid.

Example 90

l- [3- (4-methoxyphenylthio) propanoyl] -L-proline

By substituting 4-methoxybenzenethiol for 4-chlorobenzè-nethiol in the process of Example 81, 1- [3- (4-methoxyphenylthio) propanoyl] -L-proline is obtained.

Example 91

1- (3-methylthiopropanoyl) -L-pipecolic acid

By substituting L-pipecolic acid for L-proline in process A of Example 80, l- (3-methylthio-propanoyl) -L-pipecolic acid is obtained.

Example 92

l- [2- (4-chlorophenylthio) propanoyl] -L-proline

By substituting 2-bromopropionyl chloride for 3-bromopropionyl chloride in the process of Example 81, 1- [2- (4-chlorophenylthio) propanoyl] -L-proline is obtained.

carefully adding sodium hydroxide. The mixture is vigorously stirred at room temperature until a negative thiol reaction is obtained. The mixture is diluted with water, adjusted to pH = 8 and extracted with ethyl acetate, the aqueous phase is acidified to pH 3 and again extracted with acetate. 'ethyl. The latter extract is washed with water, dried and concentrated to dryness to obtain l- [3- (ethyldithio) propanoyl] -L-proline.

io Example 98

l- [3 - [(4-methylphenyl) dithio] propanoyl] -L-proline

A solution of 1.76 g of 4-methylphenylsulfenyl chloride in 20 ml of ether is added to a solution of 2 g of 3-mercaptopropanoyl-L-proline in 20 ml of chilled 0.5N sodium hydroxide in an ice bath. The mixture is vigorously stirred for 1 h 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 concentrated to dryness to obtain l- [3 - [(4-20 methylphenyl) dithio] propanoyl] -L-proline.

Example 99 l- [3- (phênyldithio) propanoyl] -L-proline

By substituting phenyl thiosulfinate (prepared from phenyl disulfide according to U. Weber and P. Hartter, Z. Physiol. Chem., 351.1384 (1970)) for ethyl thiosulfinate in the process of the example 97, we obtain l- [3- (phenyldi-thio) propanoyl] -L-proIine.

Example 93 30

1- [3 - [(diphenylmethyl) thio] -2-benzylpropanoyl] -L-proline 0.92 g of diphenylmethanol and 1.5 g of 1- (3-

mercapto-2-benzylpropanoyl) -L-proline in 10 ml of trifluoroacetic acid and the solution is kept at room temperature for 30 min. Excess trifluoroacetic acid is removed in vacuo to give 1- [3 - [(diphenylmethyl) thio] -

2-benzylpropanoyl] -L-proline.

Example 94

l- [4- (4-chlorophenylthio) butanoyl] - L-proline 40

By substituting 4-bromopropionyl chloride for 3-bromopropionyl chloride in the process of Example 81, 1- [4- (4-chlorophenylthio) butanoyl] -L-proline is obtained.

45

Example 95

l- [3 - [(benzylthiomethyl) thio] butanoyl] -L-proline

By substituting 3-mercaptobutanoyl-L-proline for 3-mer-captopropanoyl-L-proIine in the process of Example 82, l- [3 - [(benzylthiomethyl) thio] butanoyl] -L-proline is obtained .

50

Example 96

l- [4 - [(acetamidomethyl) thio] -2-methylbutanoyl] -L-proline

By substituting l- (4-mercapto-2-methylbutanoyl) -L-pro-line for l- (3-mercaptopropanoyI) -L-proIine in the process of Example 83, l- [4- [(acetamidomethyl) thio] -2- 55 methylbutanoyl] -L-proline.

Example 97

l- [3- (ethyldithio) propanoyl] -L-proline H1

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 vigorously stirred at room temperature for 4 h. The methanol is separated in vacuo to obtain l- (3-ethyldithiopropanoyl) -L-proline. h5

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 in

Example 100 l- [3 - [(2-phenylethyl) dithio] propanoyl] -L-proline

By substituting 2-phenylethyl thiosulfinate (prepared from phenethyl disulfide) for ethyl thiosulfinate in the process of Example 97, l- [3 - [(2-phenyl-ethyl) dithio] propanoyl is obtained ] -L-proline.

Example 101 l- [3 - [(2-hydroxyethyl) dithio] propanoyï] -L-proline

To a solution of 21 g of l, the - [(sulfinylthio) -bis- (3-propa-noyl)] -bis -L-proline in 100 ml of methanol, 4.2 g of mercaptoethanol are added and the mixture is stirred vigorously mix the reaction mixture at room temperature for 4 h. The methanol is removed in vacuo and the residue is purified by chromatography on a silica gel column to obtain l- [3 - [(2-hydroxyethyl) dithio] propanoyl] -L-proline.

Example 102

l- [2- (ethyldithio) propanoyl] -L-proline

By substituting 2-mercaptopropanoyl-L-proline for 3-mercaptopropanoyl-L-proline in the process of Example 97, l- [2- (ethyldithio) propanoyl] -L-proline is obtained.

Example 103 l- [3 - [(4-methylphenyl) dithio] butanoyl] -L-proline

By substituting 3-mercaptobutanoyl-L-proline for 3-mer-captopropanoyl-L-proline in the process of Example 98, l- [3 - [(4-methylphenyl) dithio] butanoyl] -L is obtained -proline.

Example 104

1- [3- (ethyldithio) -2-methylpropanoyl] -L-proline methyl ester

By substituting l- (3-mercapto-2-methylpropanoyl) -L-proline for 3-mercaptopropanoyl-L-proline in the process of Example 97 and then treating the product with ethereal diazomethane as in the process of l Example 72, the methyl ester of 1- [3- (ethyldithio) -2-methylpropanoyl] -L-pro-line is obtained.

17

622 503

Example 105 Example III

1 - [3- (ethyldithio) propanoyl] -L-azetidine-2-carboxylic acid 1,1 '- [dithiobis (2-D-methyl-3-propanoyl)] - bis-L-proline

By substituting 3-mercaptopropanoyI-L-azetidine-2- By substituting 3-mercapto-2-D-methylIpropanoyl-L-pro-

3-mercaptopropanoyl-L-proline carboxylic acid in the pro line to 3-mercaptopropanoyl-L-proline in the ceded method of Example 97, l- [3- (ethyldithio) pro- acid is obtained In Example 110, the l, l - [dithiobis (2-D-methyl-3-pro-

panoyl] -L-azetidine-2-carboxylic. panoyl)] - bis-L-proline which melts at 236-237 ° C.

Example 106 Example 112

l- [3 - [(4-methylphenyl) dithio] -2-methylpropanoyl] -L-hydroxy- 1,1 '- [dithiobis (2-propanoyl)] - bis-L-proline proline! u By substituting 2-mercaptopropanoyl-L-proline for the

By substituting 1- (3-mercapto-2-methylpropanoyl) -L-hy- 3-mercaptopropanoyl-L-proline in the process of example droxyproline for 3-mercaptopropanoyl-L-proline in pro 110, obtains l, r- [dithiobis (2-propanoyl)] - bis-L-proline. yielded from Example 98, we obtain l- [3 - [(4-methylphenyl) -

dithio] -2-methylpropanoyl] -L-hydroxyproline. Example 113

15 1,1 '- (dithiobis-acetyl) -bis-L-hydroxyproline

Example 107 By substituting 1- (2-mercapto-acetyl) -L-hydroxyproline for

1- [4- (ethyldithio) butanoyl] -L-pipecolic acid 3-mercaptopropionyl-L-proline in the process of the example

By substituting 4-mercaptobutanoyl-L-pipecolic acid for 110, one obtains 1,1 '- (dithiobis-acetyl) -bis-L-hydroxyproline. 3-mercaptopropanoyl-L-proline in the process of the example

97, we obtain the acid l- [4- (ethyldithio) butanoyl] -L-pipecoli- y, Example 114

than. 1,1 '- (dithiobis-acetyl) -bis-L-azetidine-2-carboxylic acid

By substituting l- (2-mercapto-acetyl) -L-azetidine-2-

Example 108 carboxylic 3-mercaptopropanoyl-L-proline in pro-

Acid l- [3- (ethyldithio) propanoyl] -5-hydroxy-L-pipecolic ce, fude I ^ example 110, we obtain the acid l, l '- (dithiobis-acé

By substituting 1- (3-mercaptopropanoyl) -5-hydroxy-25 ^ 1S "" azetldme-2-carboxy acid.

L-pipecolic to 3-mercaptopropanoyl-L-proline in pro- Example 115

yielded from Example 97, we obtain l- [3- (ethyldithio) pro Adde hr. [duhiobis (3-propanoyl)] - bis-L-pipecolic panoyl] -5-hydroxy-L-pipecohque. By substituting 3-mercaptopropanoyl-L-pipecolic acid

30 to 3-mercaptopropanoyl-L-proline in the process of Example

Example 109 pie 110, we obtain the acid l, l - - [dithiobis (3-propanoyl)] - bis-L-

l- [3 - [(2-amino-2-carboxyethyl) dithio] propanoyl] -L-proline pipecolic

A 0.5 M solution of thiocyanogen in glacial acetic acid is prepared by shaking for 10 min in a flask. Example 116

sealed 600 mg of dry lead thiocyanate with a solution of l. r. [dithiobis (3-propanoyl)] - bis-4-methyl-L-proline

75 [of bromine in 3 ml of acetic acid. After having separated By substituting i- (3-mercaptopropanoyl) -4-methyl-L-

lead bromide and excess lead thiocyanate with, ine à, a 3_mercaptopropanoyl-L-proline in the centrifugation process, 2.5 ml of this solution is mixed with 25 ml rexempIe 110, 1 is obtained, 1 '- [dithiobis (3-propanoyl)] - bis-

d a 0.41 M solution of prior cysteine hydrochloride-4-methyl-L-proline neutralized with dilute sodium hydroxide. This mixture is immediately added to 0.75 ml of a 1.0 40 solution

M of 3-mercaptopropanoyl-L-proline previously neutralized. ,.

with dilute sodium hydroxide. After 20 minutes, titrate the ^ u .. [duhiobis0.pro ^^ i)]. ^. 5.hydro ^ .L.pipé.

mix until an incipient brown color appears,.

with alcoholic iodine and the pH is adjusted to 3. The Tn substituting the l- (3-mercaptopropanoyl) -5-hydroxy-precipitate acid is separated by filtration and the fiteat is applied to a column of Liecoli at 3 -mercaptopropanoyl-L-proline in cation exchange proresin (Dowex 50) The yielded column is washed with v 110, the acid l, l - - [dithio-bis (3-is obtained with water until no more propanoyl)] - bis-5-hydroxy-L-pipecolic acid substance is removed.

then elute with a pyndine-acetate buffer of pH = 6.0.

The fractions containing cysteine disulfide and t? 7 no>

, T Example 118

3-mercaptopropanoyl-L-prolme, and they are concentrated to dryness. • ltV, [diMom2.berayi.3.propanoyl)] - bis-L.proline

By substituting l- (3-mercapto-2-benzylpropanoyl) -L-

Example 110 proline with 3-mercaptopropanoyl-L-proline in the process for

1,1 '- [dithiobis (3-propanoyl)] - bis-L-proline example 110, one obtains l, l - [dithiobis (2-benzyl-3-propa-

0.95 g of 3-mercaptopropanoyl-L-proline is dissolved in 55 nuclei)] - bis-L-proline.

20 ml of water and the pH is adjusted to 6.5 with sodium hydroxide N. An ethanolic solution is added dropwise. Example 119

iodine while maintaining the pH at 6.5 by adding with precau- Acid 1,1 '- [dithiobis (2-methyl-3-propanoyl)] - bis-L-pipecolic tion of sodium hydroxide N. When a color is obtained By substituting the acid l- (3-mercapto-2-methylpropanoyl) -

persistent yellow, the addition of iodine is stopped and o0 L-pipecolic with 3-mercaptopropanoyl-L-proline is destroyed in the pro-

color with a small amount of sodium thiosulfate. We yield from example 110, we obtain the acid 1,1 '- [dithiobis (2-

acidifies the reaction mixture with hydrochloric acid (methyl-3-propanoyl)] - bis-L-pipecolic.

concentrated and extracted with ethyl acetate. The organic phase is washed with water, dried and concentrated to dryness Example 120

to obtain l, l - [dithiobis (3-propanoyl)] - bis-L-proline. On ft5 l, the - [dithiobis (4-butanoyl)] - bis-L-proline prepares the dicyclohexylammonium salt by adding 4-mercaptobutanoyl-L-proline to the 3-mer-

dicyclohexylamine to a solution of the free acid in acetonaptopropanoyl-L-proline in the method of Example 110, trilating; it melts at 179-180 ° C. obtains l, l - [[dithiobis (4-butanoyl)] - bis-L-proline.

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18

Example 121 1,1 '- [dithiobis (2-benzyl-4-butanoyl)] - bis-L-proline

By substituting l- (4-mercapto-2-benzylbutanoyl) -L-pro-line for 3-mercaptopropanoyl-L-proline in the process of Example 110, 1,1 '- [dithiobis (2 -benzyl-4-buta-noyl)] - bis-L-proline.

Example 122 1.1 '- [dithiobis (3-butanoyl)] - bis-L-proline

By substituting 3-mercaptobutanoyl-L-proline for 3-mer-captopropanoyl-L-proline in the process of Example 110, we obtain l, l - - [dithiobis (3-butanoyl)] - bis-L -proline.

Example 123

1,1 'methyl ester - [dithiobis (3-propanoyl)] - bis-L-proline

A solution of l, l - [dithiobis (3-propanoyl)] - bis-L-proline in methanol is treated with ethereal diazomethane until a persistent yellow color is obtained. After 15 min, add a few drops of acetic acid and separate the solvents under vacuum to obtain the 1,1 '- [dithiobis (3-propanoyl)] - bis-L-proline methyl ester.

Example 124

1,1 'amide - [dithiobis (3-propanoyl)] - bis-L-proline

A 1.1 '- [dithiobis (3-propanoyl)] - bis-L-proline methyl ester solution is saturated in methanol with ammonia while cooling in an ice-water bath. The reaction mixture is kept for 16 h at ordinary temperature in a pressure flask and then the solvents are separated in vacuo to obtain the amide of 1, l - [[dithiobis (3-propanoyl)] - bis-L-proline.

Example 125

l, l - - [dithiobis (2-phenyl-3-propanoyl)] - bis-L-proline

By substituting l- (3-mercapto-2-phenylpropanoyl) -L-proline for 3-mercaptopropanoyl-L-proline in the process of Example 110, 1,1 '- [dithiobis (2-phenyl) is obtained -3-propa-noyl)] -bis-L-proline.

Example 126 1.1 '- [(sulfinylthio) -bis- (3-propanoyl)] - bis-L-proline

While cooling in an ice bath, 0.12 mole of peracetic acid is added to a stirred solution of 40 g of 1.1 '- [dithiobis (3-propanoyl)] - bis-L-proline in 500 ml of glacial acetic acid. The reaction mixture is allowed to stand overnight at room temperature and then the solvent is removed in vacuo to obtain 1,1 '- [(sulfinyIthio) -bis- (3-propanoy-1)] - bis-L-proline.

Example 127

1,1 '- [(sulfonylthio) -bis- (3-propanoyl) J-bis-L-proline

2.0 ml of a 30% hydrogen peroxide solution are added to a solution of 4 g of l, l - [dithiobis (3-propanoyl)] - bis-L-pro-line in 80 ml of glacial acetic acid and the solution is kept for 30 h at room temperature. The solvent is separated under vacuum to obtain l, l - [(sulfonylthio) -bis- (3-propa-noyl)] - bis-L-proIine.

Example 128

1,1 '- [(sulfinylthio) -bis- (2-propanoyl)] - bis-L-proline

By substituting l, l - [dithiobis (2-propanoyl)] - bis-L-pro-line for l, l - [dithiobis (3-propanoyl)] - bis-L-proline in the process of l 'Example 126, 1.1' - [(suifinylthio) -bis- (2-propanoyl)] - bis-L-proline is obtained.

Example 129

Acid l, r - [(sulfinylthio) -bis-acetyl] -bis-L-azetidine-2-carboxy-lique

By substituting the acid l, l - (dithiobis-acetyl) -bis-L-azéti-

1,1 '- [- dithiobis (3-propanoyl)] - bis-L-pro-line carboxylic dine in the process of Example 126, 1,1' - [(sulfinylthio) -bis acid is obtained -acetyl] -bis-L-azetidine-2-carboxylic.

Example 130

l, l - - [(sulfinylthio) -bis- (3-propanoyl)] - bis-4-methyl-L-proline

By substituting l, l - [dithiobis (3-propanoyl)] - bis-4-me-thyl-L-proline for l, l - [dithiobis (3-propanoyl)] - bis-L-proIine in the method of Example 126, one obtains l, l - [(sulfinyl-thio) -bis- (3-propanoyl)] - bis-4-methyl-L-proline.

Example 131

1,1 '- [(sulfinylthio) -bis- (2-benzyl-3-propanoyl)] - bis-L-proline Substituting l, l - - [dithiobis (2-benzyl-3-propanoyl)] - bis -L-proline at l, l - - [dithiobis (3-propanoyl)] - bis-L-pro! Ine in the process of example 126, one obtains l, l '- [(sulfinyl-thio) -bis- (2-benzyl-3-propanoyl)] - bis-L-proline.

Example 132 1.1 '- [(sulfinylthio) -bis- (4-butanoyl)] - bis-L-proline

By substituting l, l - [dithiobis (4-butanoyl)] - bis-L-proline for l, l - [dithiobis (3-propanoyl)] - bis-L-proline in the process of Example 126 , we obtain 1,1 '- [(sulfinylthio) -bis- (4-buta-noyl)] - bis-L-proline.

Example 133 l, l - [(sulfinylthio) -bis- (3-butanoyl)] - bis-L-proline

By substituting l, l - [dithiobis (3-butanoyl)] - bis-L-proline for l, l - [dithiobis (3-propanoyI)] - bis-L-proline in the method of the example 126, we obtain l, l - - ((sulfinylthio) -bis- (3-buta-noyl)] - bis-L-proline.

Example 134

1,1 '- [(sulfìnylthio) -bis- (2-methyl-3-propanoyl)] - bis-L-proline

By substituting l, l - [dithiobis (2-methyl-3-propanoyl)] - bis-L-proline for l, l - [dithiobis (3-propanoyl)] - bis-L-proline in the process from Example 126, there is obtained l, l - - ((sulfinyl-thio) -bis- (2-methyl-3-propanoyl)] - bis-L-proline.

Example 135

1,1 '- [(sulfinylthio) -bis- (2-phenyl-3-propanoyl)] - bis-L-proline

By substituting l, l - [dithiobis (2-phenyl-3-propanoyl)] - bis-L-proline for l, l - [dithiobis (3-propanoyl)] - bis-L-proline in the process from Example 126, 1.1 '- [(suifinyl-thio) -bis- (2-phenyl-3-propanoyl)] - bis-L-proline is obtained.

Example 136

l- [3 - [[3- (2-carboxy-1-pyrrolidinyl) -3-oxopropyl] -dithio] -2-methylpropanoylJ-L-proline

By substituting l, l - [(sulfinylthio) -bis- (2-methyl-3-pro-panoyl)] - bis-L-proline for ethyl thiosulfinate in the process of Example 97, the l- [3 - [[3- (2-carboxy-1-pyrrolidinyl) -3-oxopropyl] -dithio] -2-methylpropanoyl] -L-proline.

Example 137

1,1 '- [(sulfonylthio) -bis-acetyl)] rbis-L-hydroxyproline

By substituting l, l - (dithiobis-acetyl) -bis-L-hydroxypro-line for l, l - [dithiobis (3-propanoyl)] - bis-L-proline in the process of Example 127 , we obtain l, l - [(sulfonylthio) -bis-acetyl)] - bis-L-hydroxyproline.

Example 138

Acid 1,1 '- [(sulfonylthio) -bis- (3 -propanoyl)] - bis-L-pipecolic

By substituting l, l - - [dithiobis (3-propanoyl)] - bis-L-pipecolic for l, l - - [dithiobis (3-propanoyl)] - bis-L-proline in the process of l 'Example 127, 1.1' - [(suIfonylthio) -bis- (3-propanoyl)] - bis-L-pipecolic acid is obtained.

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25

30

35

40

45

50

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622 503

Example 139

1,1 '-f (sulfonylthio) -bis- (3-propanoyl)] - bis-5-hydroxy-L-pipecolic acid

By substituting the acid l, l - [dithiobis (3-propanoyl)] - bis-5-hydroxy-L-pipecolic for 1,1 '- [dithiobis- (3-propanoyI)] - bis- 5 L- proline in the method of Example 127, 1.1 '- [(suIfonylthio) -bis- (3-propanoyI)] - bis-5-hydroxy-L-pipe-colic acid is obtained.

Example 140 10

Acid 1, l - [(sulfonylthio) -bis- (2-methyl-3-propanoyl) J-bis-L-pipecolic

By substituting l, l - - [dithiobis (2-methyl-3-propa-noyl)] - bis-L-pipecolic for l, l - [[dithiobis (3-propanoyI)] - bis-L- proline in the process of Example 127, 15 l acid is obtained, l - [(sulfonylthio) -bis- (2-methyl-3-propanoyl)] - bis-L-pipecolic acid.

Example 141

1,1 '- [(sulfonylthio) -bis- (2-benzyl-4-butanoyl)] - bis-L-proline 2o

By substituting 1,1 '- [dithiobis (2-benzyl-4-butanoyl)] - bis-L-proline for l, r- [dithiobis (3-propanoyl)] - bis-L-pro! Ine in the method of Example 127, one obtains l, l - [(sulfonylthio) -bis- (2-benzyl-4-butanoyl)] - bis-L-proline.

25

EXAMPLE 142 3-acetylthio-2-phenylpropanoic acid

By substituting 2-phenylacrylic acid for methacrylic acid in the process of Example 25, 3-acé-tylthio-2-phenylpropanoic acid is obtained.

30

1- (3-acetylthio-2-phenylpropanoyl) -L-proline tert-butyl ester By substituting 3-acetylthio-2-phenylpropanoic acid for 3-acetyl-2-methyl-propanoic acid in the process of Example 28 , 1- (3-acetylthio-2-phenylpropanoyl) -L-proline t-butyl ester is obtained.

Example 143 l- (3-mercapto-2-pkenylpropanoyl) -L-proline

By substituting 1- (3-acetylthio-2-phenyl-propanoyl) -L-proline t-butyl ester for 1- (3-acetylthio-2-me-thylpropanoyl) -L-proline t-butyl ester in the process of example 29 and by subjecting the product to ammonolysis as in example 34, one obtains l- (3-acetylthio-2-phenylpropanoyl) -L-proline and l- (3-mercapto-2-phenylpropanoyl ) -L-proIine. 45

Example 144 1- [3- (acetylthio) -DL-propanoyl] pipecolic acid

6.5 g of pipecolic acid are suspended in 200 ml of dimethylacetamide. 8.3 g of 50 3-acetylthiopropanoyl chloride at 23 ° C are added dropwise to the suspension. A clear solution is formed and the temperature rises to 28 ° C. To this clear solution is added 10.1 g of N-methylmorpholine.

A precipitate is immediately formed and the temperature rises to 34 ° C. The mixture is heated in a water bath for 1 h and then it forms a clear solution. Upon cooling, the precipitated solid is filtered to obtain 5.1 g of 1- [3- (acetythio) -DL-propanoyl] pipecolic acid which melts at 190-200 ° C. The solvent is separated and the mixture is triturated. viscous residue with isopropyl ether to obtain 7.8 g of product which melts at 60

98-101 ° C. Recrystallization from acetone-hexane gives a solid substance with constant melting point which melts at 102-104 ° C; has an Rf value = 0.72 (silica gel, 7: 2 mixture of benzene: acetic acid).

65

EXAMPLE 145 DL-1- (3-Mercaptopropanoyl) -Pipecolic Acid

12 ml of concentrated ammonium hydroxide are stirred under nitrogen at 10 ° C. for approximately 15 minutes and then 6.6 g of l- [3- (acetylthio) -DL-propanoyl] -pipecolic acid are added to 5-10 ° C. A clear solution is formed after 2-3 minutes. The ice bath is removed and the solution is stirred at room temperature under nitrogen for 45 min. The solution is strongly acidified with 20% HCl (cooling) and the precipitated oil is extracted with three times 150 ml of ethyl acetate. The ethyl acetate extracts are dried over magnesium sulfate and the solvent is removed to obtain 6.0 g of DL-1- (3-mercapto-propanoyl) -pipecolic acid which has an Rf value of 0, 77 (silica gel, 7: 1 mixture of benzene: acetic acid).

Example 146 1- (3-Mercaptopropanoyl) -L-pipecolic acid

By substituting L-pipecolic acid for DL-pipecoli-que acid in the process of Example 144 and then subjecting the product to the process of Example 145, we obtain l- [3- (acetylthio ) propanoyl] -L-pipecolic and l- (3-mercapto-propanoyl) -L-pipecolic acid having an Rf value = 0.80 (silica gel,

20

7: 1 mixture of benzene: acetic acid); value [a] ^ = - 51.5 (c, 1.0 absolute ethanol).

Example 147

1- [3- (acetylthio) -2-methylpropanoyl] -DL-pipecolic acid 6.5 g (0.05 m) of pipecolic acid is suspended in 200 mg of dimethylacetamide, and added dropwise 9, 0 g (0.05 m) of 3-acetylthio-2-methylpropanoyl chloride. The temperature rises to 29 ° C and a clear solution is formed. 10.1 g of N-methylmorpholine are then added at once and the temperature rises to 34 ° C. The mixture is heated in a water bath for 1 h and then a clear solution is formed. It is left to stand at room temperature overnight and the precipitated solid is filtered off to obtain 6.1 g which melts at 203-204 ° C. The solvent is separated off and the viscous residue is triturated with water and 20% HCl. The yellow oil is extracted with three times 150 ml of ethyl acetate. The ethyl acetate extracts are dried over magnesium sulphate and separated to obtain 14 g of l- [3- (acetylthio) -2-methylpropanoyl] -DL-pipecolic acid in the form of a viscous oil. .

Example 148

1- (3-Mercapto-2-methylpropanoyl) -DL-pipecolic acid

Aqueous NH4OH (30 ml of water and 20 ml of concentrated NH4OH) is stirred under nitrogen at 10 ° C for 15 min. This is added to 13.0 g (0.05 m) of l- [3- (acetylthio) -2-me-thy! Propanoyl] -DL-pipecolic acid and the solution obtained is stirred for 10 min under l 'nitrogen; then at room temperature for 50 min. It is then treated with water and 20% HCl and the yellow oil is extracted with three times 150 ml of ethyl acetate. The ethyl acetate extract is dried over magnesium sulfate and separated to obtain 11.1 g of l- (3-mercapto-2-methylpropanoyl) ~ DL-pipecolic acid in the form of an oil viscous. The Rf value = 0.62 (silica gel, 7: 2 mixture of benzene: acetic acid).

Example 149

3 - [(4-methoxyphenyl) methylthio] -2-methylpropanoic acid 15.4 g (0.1 mole) of p-methoxy-a-toluenethiol is added to a solution of 8.6 g (0.1 mole) d methacrylic acid in 50 ml of 2N sodium hydroxide. The mixture is heated in a water bath for 3 h and then heated under reflux for 2 h and cooled. The mixture is extracted with ether and then the aqueous layer is acidified with concentrated HCl and extracted with dichloromethane. The acid extracts are washed with brine, dried over MgSO4 and evaporated in vacuo. The semi-solid substance obtained is taken up in 50 ml of dichlorome-

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thane, dilute with 50 ml of hexane and refrigerate. 3 - [(4-methoxyphenyl) methylthio] -2-methylpropanoic acid is isolated in the form of a crystalline solid which melts at 74-82 ° C (5.5 g).

5

Example 150

1- [3- (4-methoxyphenyl) methylthio] -2-methyl-propanoyl-L-proline tert-butylester

3.6 g (0.015 mole) of 3 - [(4-methoxyphé-nyl) methylthio] -2-methylpropanoic acid, 2.6 g (0.015 mole) of L-proline io t-butyl ester and 3 are dissolved. 1 g (0.015 mole) of dicyclohexyl-carbodi-imide in 50 ml of dichloromethane and the mixture is stirred for 30 min at 0 ° C. The cooling bath is removed and the mixture is stirred overnight (16 h). The suspension obtained is filtered and the filtrate is washed with 5% potassium bisulfate, saturated sodium bicarbonate and brine, then dried over MgSO4 and evaporated in vacuo. The clear oil obtained is applied to a 250 ml silica gel column and chromatographed using 20% ethyl acetate / hexane as eluent. The main fraction is evaporated (R (= 0.70, silica gel, ethyl acetate) until 5.5 g (93%) of 1- [3- (4- methoxyphenyl) methylthio] -2-methylpropanoyl-L-proline in the form of a clear oil. R {= 0.70 (silica gel, ethyl acetate); Rf = 0.60 (silica gel,

ether). 25

Example 151 l- (3-mercapto-2-methylpropanoyl) -L-proline

1.2 g (0.003 mole) of the ester of Example 150, 5 ml of anisole and 0.5 ml of trifluoromethane sulfonic acid are dissolved in 20 ml of trifluoroacetic acid under nitrogen and the red solution obtained is left to stand for 1 hour at room temperature. The solution is evaporated in vacuo until a red residue is obtained which is taken up in ethyl acetate and washed with water, brine and then dried over MgSO 4 and 35 qu 'we evaporate. The residue is triturated several times with hexane and the residual hexane is evaporated; the oily residue represents 0.4 g. Part of this material (180 mg) is subjected to preparative thin layer chromatography on 2 mm silica gel plates using a 75:25 40 mixture of benzene / acetic acid as the eluent. The main positive band is isolated with nitroprusside (nitroprusside) (Rf = 0.40) to obtain 135 mg of l- (3-mercapto-2-methylpropanoyl) -L-proline in the form of an oil. Thin layer chromatography using a 75:25 mixture of benzene: acetic acid 45 (R {= 0.40) and a 50:40:10 mixture of chloroform:

methanol: acetic acid (Rf = 0.62).

Example 152

l- (3-mercapto-2-D-methylpropanoyl) -L-proline 50

Under an argon blanket, 10.0 g of 1- [3- (acetylthio) -2-D-methylpropanoyl] -L-proline are suspended in 150 ml of water at 10 ° C. To this is added mixture of 5N sodium hydroxide and the pH of the solution is maintained at 13 for 1.5 h. After this time, when the absorption of sodium hydroxide has ceased, the solution is 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 concentrated until an oil is obtained. fi (} The concentrate is taken up in ethyl acetate, filtered and the filtrate is diluted with 30 ml of hexane. A new quantity of hexane is added after half an hour and then the mixture is cooled to 10 °. C for 1 h.

The crystals are filtered and washed with twice 25 ml of hexane and dried to constant weight to obtain l- (3-mercapto-2-D-methylpropanoyl) -L-proline in the form of 6.26 g white crystals that melt at 100-102 ° C.

Example 153 1 - [3-tosyloxy-2-methylpropanoyl] -L-proline

By substituting 3-tosyloxy-2-methylpro-panoic acid chloride for 3-acetylthio-2-methylpropanoic acid chloride that in the process of Example 29 B, 1- [3-tosyloxy- 2-methylpropanoyl] -L-proline.

Example 154 l- [3-acetylthio-2-methylpropanoyl] -L-proline

3.5 g of l- [3-tosyloxy-2-methylpropanoyl] -L-proline are added to a solution of 1.14 g of thiolacetic acid and 3.5 ml of triethylamine in 20 ml of ethyl acetate . The solution is kept at 50 ° C for 3 h, cooled, diluted with 100 ml of ethyl acetate and washed with dilute hydrochloric acid. The organic layer is dried and concentrated to dryness under vacuum. The residue is dissolved in acetonitrile and dicyclohexylamine is added. The crystalline precipitate is recrystallized from isopropanol in order to obtain the dicyclohexylamine salt of the melting 1- [3-acetylthio-2-D-methylpropanoyl] -L-proline.

at 187-188 ° C, at a value [a] =

-67 ° (c 1.4, EtOH).

This salt is converted into the free acid which melts at 83-85 ° C (an isomorphic form is obtained which melts at 104-105 ° C if the crystallization solution is seeded with a substance with a high melting point).

Example 155 1- (3-Mercaptopropanoyl) -L-proline t-butyl ester

To a stirred solution of 1.71 g (10 mmol) of proline t-butylester and 1.35 g (10 mmol) of 1-hydroxybenzo-triazole hydrate in 20 ml of N, N-dimethylformamide 0-5 ° C, 2.06 g (10 mmol) of N, N'-dicyclohexylcarbodi-imide are added. The mixture is stirred for 10 min, then 1.06 g (10 mmol) of 3-mercaptopropanoic acid is added in 2 ml of N, N-dimethylformamide. The mixture is then stirred at 0-5 ° C for 1 h and then at room temperature overnight.

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

The oil is taken up in a 1: 1 mixture of ethyl acetate: hexane and applied to a column of 100 g of silica gel. Elution with a 1: 1 mixture of ethyl acetate: hexane gives 1.40 g (54%) of 1- (3-mercaptopropa-noyl) -L-proline t-butyl ester as an oil. which crystallizes when abandoned. Recrystallization from ether-hexane gives 0.9 g of a colorless crystalline solid which melts at 55-60 ° C. and which is identical to the compound of Example 17.

Example 156 1 - (3-mercaptopropanoyl) -L-proline

A solution of 75 mg (0.27 mmol) of 1- [3 - [[(ethylamino) carbonyl] thio] propanoyl] -L-proline is allowed to stand in 1 ml each of concentrated ammonium hydroxide and water to room temperature for 18 h under argon. The solution is diluted with a small amount of 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 concentrated in vacuo to obtain a compound which is identical to the product of Example 18. Thin layer chromatography (silica gel; 7: 3 benzene mixture: acetic acid). Rf = 0.4.

Example 157

Methacryloyl-L-proline

23.0 g (0.2 mole) of L-proline are dissolved in 100 ml of water

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622 503

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 dropwise over 3 h. A 2N sodium hydroxide solution is added simultaneously, keeping the pH of the reaction mixture at 7.0. The addition of the base is continued for 4 h after the addition of the acid chloride has been completed. 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 extracted thoroughly with ethyl acetate. The extracts, 0 acids are washed with brine and dried over MgSO4. The ethyl acetate solution is treated with 40 ml of dicyclohexylamine and refrigerated overnight. The white precipitate obtained is filtered and dried and 29 g (39%) of white solid are obtained which melts at 202-210 ° C. The solid is crystallized from 1.5 liters of a mixture 3: 1 of acetonitrile: isopropanol to obtain 19.7 g of dicyclohexylamine salt of methacryloyl-L-proline in the form of fine white needles which melt at 202-210 ° C.

The salt is dissolved in a mixture of water and ethyl acetate and the mixture is acidified with concentrated HCl. The suspension obtained is filtered to separate a fine white precipitate which is washed well with ethyl acetate. The filtrate is saturated with sodium chloride and extracted thoroughly with ethyl acetate. The extracts are washed with brine, dried over MgSO4 and evaporated until a clear oil which solidifies. Crystallization from ethyl acetate / hexane gives 7.5 g (83%) of methacryloyl-L-proline in the form of a white crystalline solid which melts at 89-93 ° C. An analytical sample is obtained by recrystallization; it melts at 30

95-98 ° C.

Example 158 l- (3-acetylthio-2-D-methylpropanoyl) -L-proline

183 mg (0.001 mole) of methacryloyl-L-proline is dissolved in 0.5 ml of thiolacetic acid and allowed to stand at room temperature for 16 h. The solution is evaporated in vacuo until a yellow residue is obtained. Preparative thin layer chromatography (silica gel, 90: 5: 5 mixture of dichloromethane: methanol: acetic acid) allows 40 240 mg of a clear oil to be isolated as the main fraction. Thin layer chromatography (90: 5: 5 mixture of dichloromethane: methanol: acetic acid) shows that this substance is l- (3-acetylthio-2-DL-methylpropanoyI) -L-proline which corresponds to the product of Example 29 B. Rf = 0.35 45 (75:25 mixture of benzene: acetic acid), Rf = 0.38.

The oil is dissolved in 3 ml of acetonitrile, treated with dicyclohexylamine until the solution is basic and refrigerated. 106 mg of a white crystalline solid is isolated, which melts at 175-181 ° C. Crystallization from isopropanol gives the dicyclohexylamine salt of 1- (3-acetyl-thio-2-D-methylpropanoyl). ) -L-proline which melts at 187-188 ° C, identical to this product in Example 29 A.

Example 159 l- [dithiobis- (2-methyl-3-propanoyl)] - bis-L-proline

By substituting 3,3'-dithiobis-2-methylpropanoic acid for 3-acetylthio-2-methylpropanoic acid in the process of Example 29 B, we obtain l- [dithiobis- (2-methyl-3 -propa-noyI)] - bis-L-proline. Miss

Example 160 l- (3-mercapto-2-methylpropanoyl) - L-proline

10.0 g of zinc powder are added to a suspension of 5.0 g of the product of Example 159 in 100 ml of sulfuric acid h5 1.0 N and the mixture is stirred at 18 ° C for 4 h under a nitrogen blanket. The solution is then filtered, the zinc is washed with 20 ml of water and the combined filtrates are extracted with three times 75

ml of methylene chloride. The methylene chloride washes are again exhausted with 25 ml of water and then the organic solution is concentrated until an oil is obtained. This oil is taken up in 20 ml of ethyl acetate and filtered. 15 ml of hexane are added to the filtrate and the mixture is stirred for 15 min. A new volume of 30 ml of hexane is then added and the solution is cooled to 5 ° C for one hour. The mixture is then filtered and the product is washed with twice 10 ml of hexane and dried to obtain 4.17 g of product in the form of white crystals, i.e. l- (3-mercapto -2-methylpropa-nucleus) -L-proline. Thin layer chromatography, Rf = 0.60 (75:25 mixture of benzene: acetic acid as solvent).

Example 161 3-Benzylthio-2-methylpropanoic acid

By substituting α-toluenethiol for p-methoxy-cc-toluene-thiol in the process of Example 149, 3-benzylthio-2-methylpropanoic acid is obtained.

Example 162

1- [3- (benzylthio) -2-methylpropanoyl] -L-proline t-butylester By substituting 3-benzylthio-2-methylpropanoic acid for 3 - [(4-methoxyphenyl) methylthio] -2- acid methylpropanoic acid In the process of Example 150, the t- butyl ester of 1- [3- (benzylthio) -2-methylpropanoyl] -L-proline is obtained.

Example 163 1 - [3- (benzylthio) -2 ~ methylpropanoyl] -L-proline

7.8 g of 1- [3- (benzylthio) -2-methylpropanoyl] -L-proline t-butyl ester are dissolved in a mixture of 55 ml of anisole and 110 ml of trifluoroacetic acid. After keeping for 1 hour at room temperature, the solvent is removed under vacuum and the residue is dissolved in ether, washed several times with saturated sodium chloride, dried over magnesium sulphate and dried. evaporated to dryness under vacuum to obtain l- [3- (benzylthio) -2-methylpropanoyl] -L-proline. Rf = 0.5 (silica gel, 3: 1 benzene mixture: acetic acid), R {= 0.5. (Silicagel, 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water.)

Example 164 1 - (3-mercapto-2-methylpropanoyl) -L-proline

0.1 g of l- [3- (benzylthio) -2-methyl-propanoyl] -L-proline is suspended in 10 ml of boiling liquid ammonia and small pieces of sodium are added with stirring until let it appear a persistent blue color. The color is destroyed with a few crystals of ammonium sulphate and the ammonia is allowed to 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 concentrated to dryness under vacuum to obtain l- (3-mercapto-2-methylpropa-noyl) -L-proline. Rf = 0.35 (silica gel; 3: 1 mixture of benzene: acetic acid), Rf = 0.5 (silica gel; 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water) which is identical to the compound from example 34.

EXAMPLE 165 3-Triphenylmethylthio-2-methylpropanoic acid

A solution of 1.2 g of 3-mercapto-2-methylpropanoic acid and 2.9 g of trityl chloride in 50 ml of methylene chloride is kept at room temperature for 2 hours. The mixture is heated in a water bath for 20 min then evaporated to dryness under vacuum 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 concentrated to dryness to obtain 3-triphenylmethyl-thio-2-methylpropanoic acid. Rf = 0.8 (silica gel, 3: 1 mixture of benzene: acetic acid).

622 503

22

Example 166

1- [3- (triphenylmethylthio) -2-methylpropa-noyl] -L-proline tert-butylester

By substituting 3-triphenylmethylthio-2-methylpro-panoic acid for 3 - [(4-methoxyphenyl) methylthio] -2-methylpropanoic acid in the process of Example 150, t-butylester is obtained of 1- [3- (triphenylimethylthio) -2-methylpropanoyl] -L-proline.

Example 167 10

l- [3- (triphenylmethylthio) -2-methylpropanoyl] - L-proline

1.8 g of 3-triphenylmethylthio-2-methyl-propanoic acid and 0.8 g of N, N'-carbonyldi-imidazole are dissolved in 10 ml of tetrahydrofuran with stirring at room temperature.

After 20 min, the solution is added to a mixture of 0.6 g of 15 L-proline and 1 g of N-methylmorpholine in 20 ml of dimethylacetamide. The mixture obtained is stirred overnight at room temperature, concentrated to dryness and the residue is dissolved in a mixture of ethyl acetate and 10% aqueous potassium bisulfate. The organic layer is separated and dried and concentrated to dryness in vacuo to give 1- [3- (triphenylmethylthio) -2-methylpropanoyl] -L-proline. Rf = 0.4 (silica gel, 3: 1 mixture of benzene: acetic acid), Rf = 1.0 (silica gel, 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water). 25

Example 168 l- (3-mercapto-2-methylpropanoyl) -L-proline

5 g of 1- [3- (triphenylmethyl-thio) -2-methylpropanoyl] -L-proline t-butyl ester are dissolved in a mixture of 55 ml of anisole and 110 ml of trifluoroacetic acid. After having kept 1 hour at room temperature, the solvents are separated under vacuum and the residue is applied to a column of silica gel balanced with a 75:25 mixture of benzene: acetic acid and eluted with the same solvent. The fractions corresponding to the components having an Rf value of 0.40 are combined (thin layer chromatography; silica gel with the same mixture of solvents) and concentrated to dryness to obtain l- (3-mercapto-2-methylpro- panoyl) -L-proline. Rf = 0.62 (silica gel, 50:40:10 mixture of chloroform / methanol: acetic acid: water) which is identical 40 to the compound of Example 34.

Example 169 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, 2.8 g are added boron trifluoride etherate. After 2 h, 4 g of potassium carbonate are added, the mixture is stirred and filtered. The filtrate is concentrated to dryness to obtain 3- (tetrahydropyran-2-ylthio) -2-methylpropanoic acid.

Example 170

l- [3- (tetrahydropyran-2-ylthio) -2-methylpropanoyl] -L-proline

By substituting 3- (tetrahydropyran-2-ylthio) -2-methylpropanoic acid for 3-triphenylmethylthio-2-methyl-pro-panoic acid in the process of Example 167, the l- [3- (tetrahydropyran-2-ylthio) -2-methylpropanoyl] -L-proline. Rf = 0.8 (silica gel, 3: 1 mixture of benzene: acetic acid). Rf = 0.75 (silica gel, 14: 1: 2: 1 mixture of methyl ethyl ketone: 60 acetic acid: pyridine: water.

Example 171 l- (3-mercapto-2-methylpropanoyl) -L-proline

A solution of 1 g of 1- [3- (tetrahydropyran-2-fi5 ylthio) -2-methylpropanoyl] -L-proline is kept in a mixture of 25 ml of methanol and 25 ml of concentrated hydrochloric acid for 30 min. The solvents are separated in vacuo to give l- (3-mercapto-2-methylpropanoyl) -L-proline. Rf = 0.35 (silica gel, 3: 1 mixture of benzene: acetic acid), Rf = 0.5 (silica gel, 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water) identical to the compound of l 'example 34.

EXAMPLE 172 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 kept at ordinary temperature for 1 h. The trifluoroacetic acid is separated in vacuo and the residue is dried in vacuo over potassium hydroxide to obtain 3-acetamidomethylthio-2-methylpropanoic acid.

Example 173

l- [3- (acetamidomethylthio) -2-methylpropanoyl] -L-proline

By substituting 3-acetamidomethylthio-2-methylpro-panoic acid for 3- (tetrahydropyran-2-ylthio) -2-methylpro-panoic acid in the process of Example 170, the l- [3- (acetamidomethylthio) -2-methylpropanoyl] -L-proline. Rf = 0.2 (silica gel, 3: 1 mixture of benzene: acetic acid), Rf = 0.3 (silica gel, 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water).

Example 174 l- (3-mercapto-2-methylpropanoyl) -L-proline

1.4 g of 1- [3- (acetamidomethylthio) -2-methyl-propanoyl] -L-proline and 1.93 g of mercuric acetate are dissolved in a mixture of 25 ml of acetic acid and 25 ml of water. After 1 hour of stirring in a water bath, hydrogen sulfide is bubbled through until no more precipitation of mercuric sulfide is observed. The mixture is filtered, the precipitate is washed with ethanol and the filtrate is concentrated to dryness under vacuum to obtain l- (3-mercapto-2-methylpropanoyl) -L-proline. Rf = 0.35 (silica gel, 3: 1 benzene mixture: acetic acid). Rf = 0.5 (silica gel, 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water). This compound is identical to that of Example 34.

Example 175

1- (3-Mercapto-2-methylpropanoyl) -L-proline tert-butylester

To the cold solution (5 ° C) of 1.2 g (10 mmol) of 3-mercapto-2-methylpropanoic acid and 1.7 g (10 mmol) of t-bu-tylester of L-proline in 25 ml of dichloromethane, 2.26 g of dicyclohexylcarbodi-imide in 5 ml of dichloromethane are added in portions. After 2 h at room temperature, 5 drops of acetic acid are added, the mixture is filtered and the filtrate is evaporated until an oily residue is obtained. This residue is taken up in 20 ml of a 3: 1 mixture of petroleum ether: ethyl acetate and it is applied to a 150 ml silica gel column prepared in petroleum ether. The fraction eluted with a 1: 1 mixture of petroleum ether: ethyl acetate contains the product, that is to say the 1- (3-mercapto-2-methyl-propanoyl) -L t-butyl ester. -proline. This fraction (0.6 g) is dried over P205 under vacuum for 12 h. Rf = 0.6 (silica gel, 3: 1 mixture of benzene: acetic acid), Rf = 0.8 (silica gel, 14: 1 mixture: 2: 1 of methyl ethyl ketone: acetic acid: pyridine: water).

Example 176 l- (3-mercapto-2-methylpropanoyl) -L-proline

By substituting the 1- (3-mercapto-2-methyl ~ propanoyl) -L-proline t-butylester for the 1- (3-mercaptopropa-nucleus) -L-proline t-butylester in the process of Example 18 C, l- (3-mercapto-2-methylpropanoyl) -L-proline is obtained. R {= 0.35 (silica gel, 3: 1 mixture of benzene: acetic acid), Rf = 0.5 (silica gel, 14: 1: 2: 1 mixture of methyl ethyl ketone: acetic acid: pyridine: water). The compound is identical to that of Example 34.

23

622 503

The racemic form of the final product of any of the preceding examples is prepared using the starting amino acid of the DL- form instead of that of the L- form.

Likewise, form D- of the end products of any of the preceding examples is prepared using the starting amino acid of form D- instead of that of form L-.

VS

Claims (22)

622,503 CLAIMS 1. Process for the preparation of a compound of formula: r3 I H2C- (C H) m 2 2. Method according to claim 1, characterized in that acyl a compound of formula: R3 I H2C— (C H) m I HN —C H-COR with a compound of formula: R4 R! I I (CH2) -CH I I S C = 0 in which n = 1 or 2 to form a product of formula I where n = 1 or 2 and R2 is a hydrogen atom, the other symbols having the same meaning as above. 3. Method according to claim 1 or 2, characterized in that said acylation is carried out in the presence of a coupling agent. 4. Method according to claim 1 or 2, characterized in that the acid is in an activated form. 4 1 I! I I R2-S- (C H) n-C H-CO-N - CH -COR wherein R is a hydroxyl group, NH2 or lower alkoxy; R, and R4 are each a hydrogen atom, a lower alkyl, phenyl or lower phenylalkyl group; R2 is a hydrogen atom, a lower alkyl, phenyl, substituted phenyl group where the substituent of the phenyl group is a halogen atom, a lower alkyl or lower alkoxy group, phenyl lower alkyl, diphenyl lower alkyl, triphenyl lower alkyl, alkyl lower-thiomethyl, phenyl-lower alkyl-methyl, lower alkanoyl-amido-methyl, O M M He II II R5 — C -, R5 — M — C—, Rg — NH — C -, R (, - S— or R7; R3 is a hydrogen atom, a hydroxyl group or a lower alkyl group; R5 is an alkyl group lower, phenyl or lower phenylalkyl; R6 is a lower alkyl, phenyl, substituted phenyl group where the substituent of the phenyl group is a halogen atom, a lower alkyl or lower alkoxy group, hydroxy lower alkyl or amino (carboxy) lower alkyl ; r3 I m (HC) CH2 Ri r4 II II R7 is R-OC-HC —N -CO-C H- (C H) n-S (0) p-; M is O or S; m is 1,2 or 3; n and p each = 0.1 or 2; as well as their basic salts, characterized in that a compound of formula: r3 is acylated I H2C (C H) m I I (H) HN C H-COR with an acid of formula: R4 R] I I X- (CH) n-C H-COOH (m) or a functional derivative of this acid, in which formula X is an R2S or bromo, chloro, iodo or tosyloxy radical and then when X is different from R2S, in that the product obtained is then subjected to a displacement reaction with the anion of a thiol or thio-acid of formula: R2-SH 5 where R, R [, R4 and n have the same meaning as above and m = 2. 5 5. Method according to claim 1 or 2, characterized in that a product of formula I is reacted in which R2 is a hydrogen atom with a halogenated compound of formula M II R5-M-C -X where X is a halogen atom to form a product in which R2 is the group M II R5-M-C -. 6. Method according to claim 1 or 2, characterized in that a product of formula I in which R2 is a hydrogen atom is reacted with a compound of formula R5-N = C = M to form a product where R2 is the group M II R5-NH-C -. 7. Method according to claim 1, characterized in that R is a hydroxyl or lower alkoxy group, Rx is a hydrogen atom or a lower alkyl group, R2 is a hydrogen atom, an R5-CO group, R ^ -S- or R7, R3 and R4 are each a hydrogen atom, R5 is a lower alkyl or phenyl group, Rg is a lower alkyl group, R7 is the group: n TT R-OC-I N-CO-C H- (C H) „- S- where R, Rl5 R4 and n have the same meaning as above and m = 2. 8. Method according to claim 2, characterized in that R is a hydroxyl or lower alkoxy group, Rj is hydrogen or a lower alkyl group, R3 and R4 are each hydrogen and m is 2. 9. Method according to claim 1 or 2, characterized in that the product has the formula: ? O R2-S- (CH2) n-C H-CO-N 1— COR wherein R is a hydroxyl group, R, is a hydrogen atom or a lower alkyl group, and R2 is a hydrogen atom. 10 10. Method according to claim 1, characterized in that the product has the formula: 11. Method according to claim 1, characterized in that the product is l- (3-mercapto-2-D-methylpropanoyl) -L-proline. 12. Method according to claim 1, characterized in that a compound of formula I is prepared in which R2 is a lower alkanoyl, benzoyl, or lower alkanoyl-amidomethyl group, then in that this group is replaced by a hydrogen atom. 13. Process for the preparation of a compound of formula I in which n is equal to 1, and the other symbols have the same meaning as in claim 1, characterized in that a compound of formula is acylated: r3 I h2c- (ch) m I I hn -c h-cor with an acid of formula: R4 R) I I c h = c -cooh and in that the product obtained is subjected to an addition reaction with a thiol or thio-acid of formula R2-sh. 14. The method of claim 13, characterized in that said acylation is carried out in the presence of a coupling agent. 15. The method of claim 13, characterized in that the acid is in an activated form. 15 16. Method according to claim 13, characterized in that a product of formula I is reacted in which R2 is a hydrogen atom with a halogenated compound of formula m II r5-m-c -x where X is a halogen atom to form a product in which R2 is the group m R5-m-c -. 17. The method of claim 13, characterized in that a product of formula I in which R2 is a hydrogen atom is reacted with a compound of formula R5-N = C = M to form a product where R2 is the group 18. The method of claim 13, characterized in that R is a hydroxyl or lower alkoxy group, Rj is a hydrogen atom or a lower alkyl group, R2 is a hydrogen atom, a group R5-CO, R6- S- or R7, R3 and R4 are each a hydrogen atom, R5 is a lower alkyl or phenyl group, R6 is a lower alkyl group, R7 is the group: wherein R is a hydroxyl group, Rj is a hydrogen atom or a lower alkyl group, and R2 is a hydrogen atom. 19. The method of claim 13, characterized in that R is a hydroxyl or lower alkoxy group, Rj is hydrogen or a lower alkyl group, R3 and R4 are each In of hydrogen and m is 2. 20. Method according to claim 13, characterized in that the product has the formula: laughed I R2-S- (CH2) „- C H-CO-N HORN m R5-NH-C-. 20 ■ 25 30 35 40 45 50 55 60 r. I R-j-S- (CHT) „- C H-CO-N HORN rock- not. 622 503 Ri R4 I I n-co-c h- (c h) n — s— in which R is a hydroxyl group, R! is a hydrogen atom or a lower alkyl group, and R2 is a benzoyl or lower alkanoyl group. 21. Method according to claim 13, characterized in that the product has the formula: 25 Ri I R2-S- (CH2) n-C H-CO-N HORN in which R is a hydroxyl group, R! is a hydrogen atom or a lower alkyl group, and R2 is a benzoyl or lower alkanoyl group. 22. Method according to claim 13, characterized in that the product is l- (3-mercapto-2-D-methylpropanoyl) -L-pro-line.