KR890000769B1 - Process for preparing of proyline derivatives - Google Patents

Abstract

Title compds. (I)[R=cyclopropane carbonyl, cyclohexane carbonyl, etc.; A=glycine, sarcocine, etc. were prepd.. Thus, 5.97g N- cyclohexane carbonyl-D-alanine was dissolved in 100ml THF and treated with 5.84g carbonyldiimidazole at -20 to -15≰C. After 1hr, the mixt. was teated with 3.6g 3-mercapto-2-D-methylpropanoic acid at -15≰C -10≰C for 1hr, stirred for 1hr at room temp. and concd.. The resulting precipitate was dissolved in 40ml H2O, extd. with ethylacetate and dried with MgSO4 to give 7.50g 3-(Ncyclohexane carbonyl-D-alanylthio) -2-D-methyl propanoic acid.

Description

Preparation of Proline Derivatives

The present invention is of general formula (I)

Wherein R is an acyl group bound to an α-amino group of an amino acid selected from the group consisting of cyclopropanecarbonyl, cyclohexanecarbonyl and adamantane carbonyl groups, A is a residue of glycine, salcosine or α-D-amino acids And a novel proline derivative represented by the α-carbonyl group forming a thiol ester bond with a sulfur atom, and a salt thereof which is acceptable as a medicament.

Compounds similar to the compound represented by formula (I), for example, a compound in which R is a benzoyl group, an acetyl group, a t-butyloxycarbonyl group, and A is an L-α-amino acid are described in British Patent Application 20503 59A. . EP 9898Al also describes compounds wherein R is a benzoyl group, an acetyl group, a t-butyloxycarbonyl group, a cyclopentanecarbonyl group and the like and A is an L-α-amino acid. EP 35383Al also describes compounds wherein R is a benzoyl group and A is a D-phenylalanyl group. However, there is no document specifically describing the compound represented by the general formula (I). That is, the compound represented by general formula (I) is useful as a medicament as a novel compound of the non-patent literature also mentioned later.

In the general formula (I), the amino acid residue represented by A is a residue of glycine, salcosine or α-D-amino acid, and examples of α-D-amino acid include D-alanine, D-leucine, D-asparagine and D- Methionine, D-glutamine, D-phenylalanine, D-tryptophan, D-ornithine, D-phenylglycine, D-threonine, D-glutamic acid, D-arginine, D-cysteine, D-aspartic acid, D-histidine, D- Neutral amino acids such as isoleucine, D-proline, D-lysine, D-serine, D-tyrosine, D-valine, acidic or basic amino acids or aliphatic amino acids, amino acids with aromatic or heterocycles, alicyclic amino acids There is a number. Moreover, functional groups, such as a hydroxyl group, a melcapto group, an amino group, and a carboxyl group, which these amino acids have may be substituted by lower alkyl group, benzyl group, lower alkanoyl group, etc.

Preferred examples of A include glycine, salcosine, D-alanine, D-leucine, D-methionine, D-glutamine, D-phenylalanine, D-tryptophan and D-phenylglycine.

In the structural formula represented by general formula (I)

There is a subsidiary carbon in the form, D-type, L-type and mixed DL forms thereof. These are all included in the scope of the present invention, among which D-type and DL-type are preferable in terms of bioactivity. In addition, the group in general formula (I)

That is, the proline residues also include D- and L-form stereoconfigurations and mixed DL-types thereof, all of which are included in the scope of the present invention, and L- and DL-types are preferable in terms of bioactivity.

Examples of acceptable salts for the proline derivatives represented by the general formula (I) include alkali metal salts such as sodium or potassium, alkaline earth metal salts such as calcium and magnesium, and salts with basic amino acids such as arginine and lysine. Among them, calcium salts and lysine salts are preferable.

The present invention provides a general formula (II) as a preparation method of the proline derivative represented by the general formula (I) as described above or an acceptable salt thereof.

(Wherein A 'is glycine, salcosine or, optionally, an α-D-amino acid residue having a protecting group, and R has the same meaning as in the preceding). )

(Wherein R 'means a hydrogen atom or a protecting group of a carboxyl group) or a reactive derivative thereof, and then reacts with a salt which is acceptable as a medicament depending on the purpose if the protecting group is present in the reaction product. It is a manufacturing method characterized by converting.

When the compound represented by the general formula (II) has a functional group such as a melcapto group, a hydroxyl group, an amino group, or a carboxyl group in a free state in which A in the general formula (I) is not involved in the reaction, they are protected. It also means derivatives in some cases.

When protecting a functional group that cannot be involved in the reaction present in A ', a group that can be removed under relatively mild conditions among those conventionally used in the field of peptide synthesis is used.

For example, the protection of the mercapto group is an aralkyl group such as trityl, benzyl, and p-methoxybenzyl, the protection of hydroxyl is benzyl, the protection of amino is t-butyloxycarbonyl, and the protection of carboxyl is t- Each of the butyl groups can be used, and all of them can be removed by applying hydrogen fluoride, trifluoroacetic acid or hydrogen chloride. The protection of the carboxyl group can also be carried out using a silyl group substituted with a lower alkyl group, for example trimethylsilyl group, which is removed by treatment with water. In the formula (III), when R 'represents a protecting group of the carboxyl group, the protecting group and the removing means are the same as those of the carboxyl group described above.

The reactive derivative of the compound represented by formula (II) refers to a derivative in which the carboxyl group is involved in the reaction. Activation means an activation means commonly used in the field of peptide synthesis such as active amide, acid halide, active ester, mixed acid anhydride, etc. It is done by employing. Among them, active esters with N-hydroxy succinimide, mixed acid anhydrides with monocarbonate and active amides with carbonyldiimidazole are preferred examples. Carbodiimides such as dicyclohexylcarbodiimide may be used as a condensing agent to form an amide bond between the carboxyl group and the imino group.

The reactive derivative of the compound represented by general formula (III) means the derivative in which the imino group of the compound is activated, and activation can be performed by applying the means normally used in the field of peptide synthesis. For example, a method of introducing and activating a silyl group such as a trimethylsilyl group, a so-called phosphazo method using a phosphorus compound such as phosphorus trichloride (Ann. Chem., 572 96 (1951)), a phosphite ester such as tetraethyl ester of pyrophosphate The phosphite ester method using these, and also what is called a N-carboxy anhydride method (NCA method), etc. are mentioned.

The reaction is carried out using an inert organic solvent such as tetrahydrofuran, dioxane, dimethylformamide, hexanemethylphosphotriamide, chloroform, dichloromethane, acetonitrile and the like.

The reaction is usually carried out under cooling to room temperature. That is, usually -50 degreeC-20 degreeC, Preferably it is -30-10 degreeC.

The reaction time varies depending on the reaction temperature, the compound provided to the reaction, the solvent, and the like, and is usually selected in the range of 0.5 to 48 hours, preferably 1 to 6 hours.

After the amide formation reaction is carried out, when the product has a protecting group it is removed. Thus, the removal can be performed using the means described for each protector.

Isolation and purification of the target product from the reaction mixture can be carried out according to a conventional method. For example, various chromatographic chromatography using a porous polymer such as silica gel, dextran crosslinked polymer, styrene-divinylbenzene or acrylic acid ester can be applied. In this case, the solvent is appropriately selected from chloroform, ethyl acetate, methanol, ethanol, tetrahydrofuran, benzene, water, acetonitrile and the like. It is also possible to apply the method of isolating the product in the form of an organic salt such as dicyclohexylamine and treating it with an acid such as hydrochloric acid and potassium hydrogen sulfate to liberate the target compound.

Since the compound of the general formula (I) thus obtained has a carboxyl group at the proline moiety, salts with various basic substances can be formed if desired, and salts with basic substances which can be accepted as pharmaceuticals are particularly important. These salts can be produced by a conventional method, that is, by treating the carboxyl groups with sugar molar amounts of the aforementioned bases.

The compound represented by general formula (II) which is a starting material of this invention can be manufactured easily by the following method.

General formula (VI)

R-OH

Wherein R is the same as the foregoing, or the reactive derivative in the carboxyl group and the general formula (VII)

H ₂ NA ″ -COOR ″

C=O을 제외한 기를 뜻하며, R″은 수소원자 또는 카르복실기의 보호기를 뜻한다.)로 나타내는 아미노산류 또는 그 반응성 유도체를 반응시키고,이어서 R″가 보호기인 경우는 이를 제거하여 일반식(VIII)(Wherein A ″ represents the group NH and the group from the amino acid residues

A group excluding C = O, and R ″ means a protecting group of a hydrogen atom or a carboxyl group.) And an amino acid group or a reactive derivative thereof, and then, when R ″ is a protecting group, it is removed to remove the general formula (VIII).

R-NH-A ″ -COOH

Wherein R and A ″ are the same as the former, and then the compound represented by the general formula (VIII) or a reactive derivative thereof and the general formula (IX)

(Wherein R '' 'refers to a hydrogen atom or a protecting group of a carboxyl group) and then reacts with R' '' as a protecting group to form a compound represented by formula (II). have.

As an example of the reactive derivative of the carboxyl group of the compound represented by general formula (VI), what is normally used in the field of peptide synthesis, such as an active amide, an acid halide, an active ester, a mixed acid anhydride, is mentioned.

When R ″ of the amino acids represented by the general formula (VII) means a protecting group, examples of suitable protecting groups include t-butyl group (which can be detached by hydrogen fluoride, trifluoroacetic acid or hydrogen chloride), benzyl group (such as palladium). The catalytic reduction can be carried out by catalytic reduction), lower alkyl groups such as methyl group and ethyl group (which can be removed by hydrolysis under alkaline conditions).

A reactive derivative of amino acids represented by the general formula (VII) is a derivative in which an amino group is activated, for example, a method of introducing a silyl group such as a trimethylsilyl group, a so-called phosphazo method, a phosphite ester method, an N-carboxoxy anhydride method, or the like. Derivatives obtained by applying an activation method commonly used in the field of synthesis.

Carbodiimides such as dicyclohexyl carbodiimide may be used as a catalyst to form an imide bond between the compound represented by the general formula (VI) and the amino acids represented by the general formula (VII).

The reaction is carried out using an inert organic solvent such as tetrahydrofuran, dioxane, dimethylformamide, hexamethylphosphotriamide, chloroform, dichloromethane, acetonitrile and the like. The reaction is usually carried out under cooling to room temperature. That is, usually -50-20 degreeC, Preferably it is -30-10 degreeC.

The reaction time varies depending on the reaction temperature, the compound provided to the reaction, the solvent, and the like, and is usually selected in the range of 0.5 to 48 hours, preferably 1 to 6 hours.

In the formula (VII), when R ″ is a protecting group, the removal from the reaction product can be carried out by applying the conventional method described above.

Isolation and purification of the compound represented by general formula (VIII) from the reaction mixture are carried out by a conventional method. For example, a method of recrystallization from ethyl acetate, n-hexane, acetone or water, or decomposition of an acid through chromatography or organic salt described as an isolation and purification means of a compound represented by the general formula (I) may be applied. There is.

The reaction of the compound represented by the general formula (VIII) or the reactive derivative thereof with the compound represented by the general formula (IX) is carried out by condensation of carbodiimide such as dicyclohexylcarbodiimide with the former carboxyl group and the latter melcapto group. It can be made to use by using the reactive derivative of the compound represented by general formula (VIII) other than the method of making it react.

Examples of the reactive derivative of the compound represented by the general formula (VIII) include active amides, acid halides, active esters, mixed acid anhydrides and the like. Among them, active amides with carbonyldiimidazole are one of preferred examples.

The compound represented by general formula (IX) may be protected or liberated by the carboxyl group. Preferred examples of the protecting group include those capable of leaving under acidic conditions such as t-butyl group.

Thiol ester formation reaction is carried out using an inert organic solvent such as tetrahydrofuran, dioxane, dimethylformamide, hexamethylphosphotriamide, chloroform, dichloromethane, acetonitrile as a solvent.

The reaction is usually carried out under cooling to room temperature. That is, it is usually -50 to 20 ° C, preferably -30 to 10 ° C when the compound represented by the general formula (VIII) is used in the form of an active amide or an acid halide, and -10 to 10 ° C when used in the form of an acid anhydride. to be.

The reaction time varies depending on the reaction temperature, the compound provided to the reaction, the solvent, and the like, and is usually selected in the range of 0.5 to 48 hours, preferably 1 to 6 hours. After the thiol ester formation reaction is carried out, if R '' 'in the product is a protecting group, it is removed. Thus, the removal can be carried out by, for example, a conventional method of reacting hydrogen fluoride, trifluoroacetic acid or hydrogen chloride in the case of t-butyl group.

Isolation and purification of the target product from the reaction mixture can be carried out according to a conventional method. For example, a method of recrystallization from an organic solvent such as ethyl acetate or n-hexane, or other method for isolating and purifying the compound represented by the general formula (I) and decomposing it to an acid through chromatography or organic salt as described above. This can be done by applying the commercial method.

Another method for producing a compound of the present invention is represented by general formula (IV)

R-A'-OH

Wherein R and A 'are the same as the above.

(Wherein R 'is the same as the former) and reacted with the compound represented by the above, and if necessary, if a protecting group is present, it is removed and converted into a salt that can be accepted as a medicament depending on the purpose.

Compounds represented by the general formula (IV) are protected in the case where A in the general formula (I) has a functional group such as a melcapto group, a hydroxyl group, an amino group, or a carboxyl group in a free state in which A cannot participate in the reaction. It also means derivatives in some cases.

In the case of protecting a functional group that cannot be involved in the reaction present in A ', a group that can be removed under relatively mild conditions among those commonly used in the field of peptide synthesis is used.

For example, the protection of the mercapto group is an aralkyl group such as trityl, benzyl and p-methoxybenzyl groups, the protection of hydroxyl groups is benzyl, the protection of amino groups is t-butyloxycarbonyl and the protection of carboxyl groups is t-butyl Each of the groups can be used to remove them, and all of them can be removed by applying hydrogen fluoride or hydrogen chloride.

The carboxyl group can also be protected using a silyl group substituted with a lower alkyl group, for example trimethylsilyl group, which is removed by treatment with water.

In the general formula (V), when R 'represents a protecting group of a carboxyl group, the protecting group and the removing means are the same as described above.

The reactive derivative of the compound represented by general formula (IV) means the derivative | guide_body which activated the carboxyl group which participates in reaction, and activation is performed by taking the form of active amic acid halide, active ester, mixed acid anhydride, etc. Among them, active amides with carbonyldiimidazole are one of preferred examples. Moreover, carbodiimides, such as dicyclohexyl carbodiimide, can be used as a condensing agent, and the carboxyl group and a melcapto group can be made to react.

The reaction of the compound represented by formula (IV) or its reactive derivative with the compound represented by formula (V) is carried out in a solvent, and examples of the solvent include tetrahydrofuran, dioxane, dimethylformamide, hexamethylphosphotriamide, chloroform, Inert organic solvents such as difluoromethane and acetonitrile are used. The reaction is usually carried out under cooling to room temperature. In other words, when the compound represented by general formula (IV) is usually used in the form of an active amide or an acid halide, it is -30 to 10 ° C, or -10 when it is used in the form of an acid anhydride. It is -10 degreeC.

The reaction time varies depending on the reaction temperature, the compound provided to the reaction, the solvent, and the like, and is usually selected in the range of 0.5 to 48 hours, preferably 1 to 6 hours. After the thiol ester formation reaction, the product is removed if it has a protecting group. Thus the removal can be done using the means described for each protector.

Isolation and purification of the target product from the reaction mixture can be carried out according to the conventional method as described above. For example, various chromatographic chromatography using porous polymers such as silica gel, dextran crosslinked polymer, styrene-divinylbenzene or acrylic acid ester can be applied. At this time, the solvent is appropriately selected from chloroform, ethyl acetate, methanol, ethanol, tetrahydrofuran, benzene, water acetonitrile and the like. It is also possible to apply the method of isolating the product in the form of an organic salt such as dicyclohexylamine and treating it with an acid such as hydrochloric acid and potassium hydrogen sulfate to liberate the target compound.

The objective compound of the present invention, i.e., the proline derivative represented by the general formula (I) and its acceptable salt as a medicament thereof, inhibits angiotensin converting enzyme and thus prevents the production of angiotensin-II from angiotensin-I, thereby causing hypertension It is useful for treatment and as a therapeutic agent for heart failure.

Next, the result of measuring the inhibitory activity of angiotensin converting enzyme with respect to some of the target compounds of this invention is shown.

(1) How to measure

Angiotensin converting enzyme extracted from rabbit lung was used. 0.111M boric -Na ₂ CO ₃ buffer (pH 8.3) 0.6ml, 25mM benzoyl-glycyl Heath peptidyl-leucine (substrate) 0.111M boric -Na ₂ CO ₃ buffer (pH 8.3) containing 0.2ml and the sample compound (according to the invention Compound of interest) 0.1 ml of 0.111 M boric acid-Na ₂ CO ₃ buffer (pH 8.3) containing 10 ⁻⁸ to 10 ⁻³ M was placed in a test tube and preincubated at 37 ° C. for 5 to 10 minutes. Next, 0.1 ml of a solution of an enzyme (acetone powder) extracted from the rabbit lung was added, and incubation was performed at 37 ° C for 30 minutes. The benzoyl glycine produced by the enzyme was extracted with ethyl acetate under acidic hydrochloric acid, and quantified by ultraviolet absorption at 228 nm. In the case of no inhibitory activity, the enzyme activity was 100 and the relative activity of the enzyme when the sample compound was added was determined, and the concentration of the sample compound when the relative activity was 50% was obtained (I ₅₀ value). ).

(2) Measurement result

compound

No. 1 N- [3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

No. 2 N- [3- (N-cyclopropanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

No. 3 N- [3- (N-cyclohexanecarbonylglyciylthio) -2-D-methylpropanoyl] -L-proline

No. 4 N- [3- (N-cyclohexanecarbonyl-N-methylglyciylthio) -2-D-methylpropanoyl] -L-proline

No. 5 N- [3- (N-cyclopropanecarbonylglyciylthio) -2-D-methylpropanoyl] -L-proline

No. 6 N- [3- (N-adamantanecarbonylglycilothio) -2-D-methylpropanoyl] -L-proline

No. 7 N- [3- (N-cyclohexanecarbonyl-D-phenylalanylthio) -2-D-methylpropanoyl] -L-proline

No. 8 N- [3- (N-cyclohexanecarbonyl-D-loylsilthio) -2-D-methylpropanoyl] -L-proline

No. 9 N- [3- (N-cyclohexanecarbonyl-D-tryptiphylthio) -2-D-methylpropanoyl] -L-proline

No. 10 N- [3- (N-cyclohexanecarbonyl-D-phenylglyciylthio) -2-D-methylpropanoyl] -L-proline

No. 11 N- [3- (N-cyclohexanecarbonyl-D-methionylthio) -2-D-methylpropanoyl] -L-proline

No. 12 N- [3- (N-cyclohexanecarbonyl-D-glutaminylthio) -2-D-methylpropanoyl] -L-proline

No. 13 N- [3- (N-adamantanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

The objective compound of the present invention has such a function and is superior in sustainability compared to a known compound, for example, 3-mercapto-2-D-methylpropanoyl-L-proline (common name captopril captopril) and 1 It is desirable in terms of blood pressure management because it can reduce the number of doses per day.

In addition, the target compound of the present invention is that the known compound, such as captopril, may cause symptoms of orthostatic hypotension due to the rapid suppression at the beginning of administration (Lancet Vol. 1, No. 8115, p 557 (1979. 3. 10)) In the compound of interest of the present invention, the coercive action at the beginning of administration is alleviated, so that orthostatic hypotension is less likely to appear. In addition, drugs having free melcapto groups, such as captopril, exhibit various side effects that are thought to be due to the melcapto group. For example, palate abnormalities, the appearance of urine proteins, granulocytopenia, skin diseases with fever have been reported. Lancet Vol. 1, No. 8160, p 150 (19 January 1980): Vol. 2, No. 8186, p 129 (July 19, 1980): South African Medical Journal Vol. 58, 172 (1980). On the other hand, the target compound of the present invention is less likely to produce a mercapto group because its thiol ester bond is less likely to be hydrolyzed in vivo, and therefore, there is little concern that the thiol ester bond may have the above side effects, which are thought to be caused by the melcapto group. .

The proline derivative represented by the general formula (I) and salts which can be used as medicaments thereof are prepared as tablets, capsules, granules, powders, syrups, elixirs or the like for oral administration or as sterile solutions or suspensions for parenteral administration. I can do it.

Therefore, it can be used as a pharmaceutical composition which is used as an adjuvant, such as excipients, carriers, binders, stabilizers, flavors, etc., which are one kind or several kinds of pharmaceutical compounds of the present invention as active ingredients.

Oral dosages for adults are usually from 0.5 mg to 2 g per day, preferably from about 1 mg to 50,000 mg per day. In the case of parenteral administration, it is usually 0.1 mg to 600 mg, preferably about 0.3 to 30 0 mg per day.

Next, specific examples of the compound of the present invention will be described with reference to Examples, but the present invention is not limited to these Examples.

Example 1

Synthesis of Raw N-Substituted Amino Acids

(A) 4.5 g of D-alanine is dissolved in 230 ml of an aqueous 1N-Na ₂ CO ₃ solution and stirred. 100 ml of tetrahydrofuran solution containing 9.0 g of cyclohexanecarbonyl chloride was added dropwise to the solution at 5 to 10 DEG C, stirred at the same temperature for 30 minutes, and then stirred at room temperature for 1.5 hours, and then 2N-HCl solution was added to the reaction solution to pH. Let it be 1-2. Ethyl acetate is added to extract the organic layer. The organic layer is washed with saturated brine, dried over magnesium sulfate, and the filtrate is concentrated under reduced pressure to obtain a crude compound. Recrystallization from ethyl acetate-n-hexane yields 4.65 g of n-cyclohexanecarbonyl-D-alanine.

[α] _D = + 26.6 °

(B) 3.0 g of an ester of adamantanecarboxylic acid and N-hydroxy succinimide are dissolved in 30 ml of tetrahydrofuran solution, and 5 ml of water containing 0.89 g of D-alanine and 1.1 g of triethylamine is added thereto at 5 ° C. Stir overnight. Concentrate under reduced pressure, remove THF, add water to the residue, and add 2N-HCl solution to pH 1-2. Hereinafter, 0.38 g of N-adamantanecarbonyl-D-alanine is obtained as described above.

[α] _D = + 11.6 ° (C = 1.0, MeOH)

The following compounds are obtained using the method (a) or (b).

Example 2

(A) 3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methyl-propanoic acid

5.97 g of N-cyclohexanecarbonyl-D-alanine is dissolved in 100 ml of dry tetrahydrofuran solution. 5.84 g of carbonyldiimidazole was added to this solution at -20 ° C to -15 ° C, stirred at the same temperature for 1 hour, and then 3.60 g of 3-melcapto-2-D-methylpropanoic acid was added to -15 ° C to -10 ° C. Stir at 1 ° C. and at room temperature. Concentrated under reduced pressure, the solvent was distilled off, 40 ml of water was added to the residue, and the mixture was extracted with ethyl acetate at pH 1-2 with 2N-HCl solution. The organic layer is washed twice with saturated brine and then dried over magnesium sulfate. Concentrate the filtrate under reduced pressure to give crude compound. Recrystallization from ethyl acetate-n-hexane yields 7.50 g (83%) of prism phase crystals of the colorless title compound. m, p. 149 ~ 152 ℃

[α] = + 46.4 ° (C = 1.07, MeOH)

NMR (CD ₃ OD, δ): 1.20 (3H, d), 1.35 (3H, d), 1.20-2.0 (11H, m), 2.40-2. 80 (1H, m), 3.05 (2H, m), 4.50 (1H, m)

(B) 3- (N-cyclohexanecarbonyl-D-phenylglyciylthio) -2-D-methylpropanoic acid

2.61 g of N-cyclohexanecarbonyl-D-phenylglycine, 1.95 g of carbonyldiimidazole, and 1.20 g of 3-melcapto-2-D-methylpropanoic acid were used to perform the same procedure as described above for the title compound. 2.07 g (57%) of yellow oil are obtained.

[α] _D = -48.7 ° (C = 1.19, MeOH)

NMR (CDCl ₃ , δ): 1.24 (3H, d), 1.20 ~ 2.10 (11H, m), 2.40 ~ 2.80 (1H, m), 3.10 (2H, m), 5.75 (1H, d), 6.40 ~ 6.80 (1H, m), 7.30 (5H, s), 8.90 (1H, s)

(C) 3- (N-cyclohexanecarbonyl-D-loisylthio) -2-D-methylpropanoic acid

(1) N-cyclohexanecarbonyl-D-leucine, 1.95 g of carbonyldiimidazole, and 1.20 g of 3-melcapto-2-D-methylpropanoic acid were treated as described in (a) above to give the title compound as an oil. Obtain 2.40 g (70%).

[α] _D = + 12.2 ° (C = 1.03, MeOH)

NMR (CDCl ₃ , δ): 0.95 (6H, d), 1.28 (3H, d), 1.20-2.10 (11H, m), 2.40-2. 80 (1H, m), 3.10 (2H, m), 4.70 (1H, m), 6.00-6.30 (1H, m), 9.20 (1H, s)

(D) 3- (N-cyclohexanecarbonyl-D-glutaminylthio) -2-D-methylpropanoic acid

2.56 g of N-cyclohexanecarbonyl-D-glutamine, 1.95 g of carbonyldiimidazole, and 1.20 g of 3-melcapto-2-D-methylpropanoic acid were used to perform the same procedure as in (A). (20%). m.p. 146 ~ 149 ℃

[α] _D = + 10.8 ° (C = 1.05, MeOH)

NMR (CD ₃ OD, δ): 1.20 (3H, d), 1.20-2.10 (11H, m), 2.30 (4H, m), 2.40-2.80 (1H, m), 3.05 (2H, m), 4.50 ( 1H, m)

(E) 3- (N-cyclopropanecarbonyl-glyciylthio) -2-D-methylpropanoic acid

0.78 g of N-cyclopropanecarbonylglycine, 1.06 g of carbonyldiimidazole, and 0.66 g of 3-melcapto-2-D-methylpropanoic acid were used to treat 0.70 g of the title compound as oil. 52%).

[α] = -33.8 ° (C = 1.01, MeOH)

NMR (CDCl ₃ , δ): 0.70 to 1.20 (4H, m), 1.25 (3H, d), 1.30 to 1.80 (1H, m), 2. 40 to 2.80 (1H, m), 3.14 (2H, m) , 4.20 (2H, d), 7.30 (1H, s)

(F) 3- (N-adamantanecarbonyl-glysilthio) -2-D-methylpropanoic acid

2.38 g of N-adamantanecarbonylglycine, 1.95 g of carbonyldiimidazole, and 1.20 g of 3-melcapto-2-D-methylpropanoic acid were used to treat 1.08 g (32) of the title compound. %) Melting Point 132 ℃ (Decomposition)

[α] _D = -8.3 ° (C = 1.01, MeOH)

NMR (CD ₃ OD, δ): 1.25 (3H, d), 1.65 ~ 2.30 (15H, m), 2.40 ~ 2.80 (1H, m), 3.14 (2H, m), 4.06 (2H, d)

3- (N-cyclohexanecarbonyl-D-phenylalanylthio) -2-D-methylpropanoic acid

(1) N-cyclohexanecarbonyl-D-phenylalanine, 1.0 g of carbonyldiimidazole, and 0.60 g of 3-melcapto-2-D-methylpropanoic acid were treated in the same manner as described above to obtain the title compound as an oil. Obtain 1.5 g (79%).

[α] _D = + 13.9 ° (C = 1.02, MeOH)

NMR (CDCl ₃ , δ): 1.25 (3H, d), 1.20 ~ 2.0 (10H, m), 2.1 ~ 3.0 (2H, m), 3.0 ~ 3.4 (4H, m), 4.95 (1H, t), 6.19 (1H, d), 7.24 (5H, s), 10.12 (1H, s)

(A) 3- (N-cyclohexanecarbonyl-D-methionylthio) -2-D-methylpropanoic acid

The title compound in the oily form was treated with 0.325 g of N-cyclohexanecarbonyl-D-methionine, 0.25 g of carbonyldiimidazole, and 0.15 g of 3-melcapto-2-D-methylpropanoic acid as described above in (A). Yield 0.29 g (64%).

[α] _D = -7.9 ° (C = 1.0, MeOH)

NMR (CDCl ₃ , δ): 1.26 (3H, d), 1.2 ~ 2.0 (10H, m), 2.09 (3H, s), 2.0 ~ 3.2 (8H, m), 4.5 ~ 5.0 (1H, m), 6.62 (1H, d), 10.07 (1H, s)

3- (N-cyclohexanecarbonyl-D-tryptiphylthio) -2-D-methylpropanoic acid

Rubber-labeled compound treated as (A) using 0.157 g of N-cyclohexanecarbonyl-D-tryptophan, 0.1 g of carbonyldiimidazole and 0.06 g of 3-melcapto-2-D-methylpropanoic acid To 0.17 g (82%).

[α] _D = -7.1 ° (C = 1.0, MeOH)

NMR (CDCℓ ₃ , δ): 1.26 (3H, d), 1.2 ~ 2.4 (11H, m), 2.5 ~ 2.9 (1H, m), 3.0 ~ 3.3 (2H, m), 3.35 (2H, d), 4.87 (1H, t), 6.4-6.9 (2H, br s), 6.9-7.8 (5H, m), 10.5 (1H, s)

Example 3

(A) N- [3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

1.51 g of 3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoic acid was dissolved in 40 ml of dry tetrahydrofuran solution, 0.61 g of triethylamine and ethyl chloroformic acid at -5 ° C. Add 0.65 g and stir. After 5 minutes, a solution obtained by dissolving 0.58 g of L-proline and 0.61 g of triethylamine in 5 ml of mole was added, and stirred at 0 ° C. for 1 hour and at room temperature for another 30 minutes. After concentration under reduced pressure, the solvent is distilled off, water is added to the residue, and the mixture is extracted with ethyl acetate to pH 1-2 with 2N-HCl aqueous solution. The organic layer is washed twice with saturated brine and then dried over magnesium sulfate. The filtrate was concentrated under reduced pressure, ethyl acetate was distilled off, and the residue was added to silica gel chromatography and eluted with a mixture of chloroform and methanol (100: 1 to 100: 2). Fractions containing the desired product are collected and concentrated under reduced pressure to obtain 0.3 g of the titled compound as rubber.

(B) The compound (a) can be produced by the following method.

6.03 g of 3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoic acid and 2.3 g of N-hydroxy pumpkin acid were dissolved in 50 ml of dry tetrahydrofuran solution, and 0-5 ° C. 4.3 g of dicyclohexylcarbodiimide was added and stirred overnight while maintaining the temperature. After completion of the reaction, the precipitate is filtered off and the insolubles are washed with a small amount of tetrahydrofuran. The filtrate and tax solution are collected, concentrated under reduced pressure, and the residue is filtered by adding ethyl acetate. The ethyl acetate solution was washed in order of 0.5N HCl, water, aqueous Na ₂ CO ₃ solution and saturated brine, and then dried over magnesium sulfate. Concentrate under reduced pressure, and solidify by adding a mixed solution of ethyl acetate and hexane (1:10) to the residue. Quantity 6.90g (87%) mp 113 ~ 116 ℃

[α] _D = + 14.2 ° (C = 1.05, MeOH)

NMR (CDCl ₃ , δ): 1.38 (6H, d), 1.20-2.20 (11H, m), 2.82 (4H, s), 2.8-3. 30 (3H, m), 4.75 (1H, m), 6.30 (1H, br s)

3.98 g of this active ester was dissolved in 40 ml of THF, and 5 ml of water and 1.26 ml of N-ethylmorpholine, in which 1.15 g of L-proline was dissolved, were added to the solution, followed by stirring overnight. After concentration under reduced pressure, the solvent was distilled off, and water was added to the residue. The ethyl acetate layer was washed with saturated brine, dried over magnesium sulfate and the filtrate was concentrated under reduced pressure. The residue was added to silica gel column chromatography, eluted with a mixed solution of chloroform and methanol (100: 1 to 100: 2), and then concentrated under reduced pressure to obtain 1.45 g of the compound. This material was confirmed to be the same as the compound of (A) by NMR data.

(C) The compound of (A) was also obtained by the following method.

4.52 g of 3- (N-cyclohexanecarbonyl-D-alanylthio) -D-methylpropanoic acid is dissolved in 5 ml of thionyl chloride, and 1 drop of dimethylformamide is added to the solution and stirred overnight at room temperature. Concentrate under reduced pressure to distill the solvent, add 2 ml of dry toluene, and distill the solvent again under reduced pressure. 10 ml of dry tetrahydrofuran solution is added to the residue and stirred. 2.3 g of L-proline and 2.5 g of Na ₂ CO ₃ are dissolved in 25 ml of water, and a tetrahydrofuran solution containing the acid chloride is added dropwise at 5 to 10 ° C. under stirring. After stirring at the same temperature for 1 hour and at room temperature for 2 hours, the reaction mixture is extracted with chloroform. The aqueous layer was adjusted to pH 1-2 with 2N HCl aqueous solution, extracted with chloroform, and the chloroform layer was washed twice with saturated brine and dried over magnesium sulfate. After concentration under reduced pressure, the residue was eluted with a mixture of chloroform and methanol (100: 1 to 100: 2) in silica gel column chromatography, and then concentrated under reduced pressure to obtain 1.6 g of the rubbery compound. This substance was confirmed to be identical with the compound obtained in the above (A) by NMR data.

(D) The compound of (A) was also obtained by the following method.

3.01 g of 3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoic acid and 1.71 g of t-butyl ester of L-proline are dissolved in 50 ml of dry dichloromethane and stirred under ice-cooling 2.15 g of clohexylcarbodiimide is added. After stirring for 0.5 hours at the same temperature, it is left at 5 ℃ overnight. After filtering the reaction solution, the insolubles were washed with dichloromethane. Collect the filtrate and washings with 1N aqueous hydrochloric acid solution, water, 1N aqueous NaHCO ₃ solution, saturated NaCl, dry over MgSO _4, and concentrate under reduced pressure to give rubbery N- [3- (N-cyclohexanecarbonyl-D-alanyl 4.3 g of t-butyl esters of thio) -2-D-methylpropanoyl] -L-proline are obtained. 4.0 g of this ester was dissolved in 30 ml of anisole, 10 ml of trifluoroacetic acid was added thereto, stirred at room temperature for 1 hour, and concentrated under reduced pressure. The excess trifluoroacetic acid was distilled off, and the residue was purified by silica gel column chromatography (2 cm x 35 cm) with methanol. Eluate with a mixture of chloroform (1: 100-3: 100). Fractions containing the desired product are collected and concentrated under reduced pressure to obtain 3.4 g of the title compound as a rubber.

This substance was confirmed to be identical with the compound obtained in Example 3 (A) by the Rf values of NMR and TLC.

Next, the physical properties of the target compound obtained in Example 3 and the other compounds obtained by applying any of Examples 3 (a) to (d) are shown in a table.

In the table, the Rf values ① and ② of the thin layer chromatography (TLC) depend on the following developing solvents, respectively.

① CHCl ₃ : MeOH: AcOH (2: 1: 0.003)

② n-BuOH: AcOH: H ₂ O (4: 1: 1)

Example 4

Various salts of N- [3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline obtained in Examples 3 and 5 will be described.

(a) Ca salt

3.98 g of the compound obtained in Example 3 or 5 was dissolved in 40 ml of methanol, 0.84 g of calcium acetate-hydrate was added and heated to reflux for 1 hour. After filtering the insolubles, the filtrate is concentrated under reduced pressure. Chloroform was added to the residue, filtered and concentrated under reduced pressure. Diethyl ether was added to the residue, filtered, and air dried to obtain 3.40 g of Ca salts of Examples 3 and 5.

[α] _D = -47.2 ° (C = 1.0, MeOH)

(b) Mg salt

3.09 g of the compound of Example 3 or 5 and 0.772 g of magnesium acetate tetrahydrate were used and treated with the following Ca salt to obtain 2.42 g of the Mg salt of Examples 3 and 5.

[α] _D = -46.6 ° (C = 1.0, MeOH)

(c) lysine salt

1.19 g of the compound of Example 3 or 5 was dissolved in 22 ml of methanol, 0.416 g of lysine was added, stirred at room temperature for 1 hour, and then concentrated under reduced pressure. Chloroform was added to the residue, concentrated under reduced pressure after filtration, and dimethyl ether was added to the residue to obtain 1.54 g of the lysine salt of Examples 3 and 5.

[α] _D = -23.1 ° (C = 1.0, MeOH)

(d) Na salt

2.27 g of the compound of Example 3 or 5 was dissolved in 25 ml of methanol, 0.514 g of sodium acetate was added thereto, stirred at room temperature for 30 minutes, and concentrated under reduced pressure. 200 ml of a mixture of methanol and chloroform (3: 100 V / V) was added to the residue, followed by filtration and concentration under reduced pressure. Methanol was dissolved in the residue, filtered and concentrated under reduced pressure. Ethyl acetate was added to the resulting residue, which was then filtered to give 1.85 g of Na salts of Examples 3 and 5.

[α] =-26.7 ° (C = 1.0, MeOH)

(e) dicyclohexylamine salt

13.1 g of the compound of Example 3 or 5 was dissolved in 120 ml of acetonitrile, 6 ml of dicyclohexylamine was added under stirring, stirred for a further 30 minutes, and left overnight. Precipitate the precipitate to air dry. The crude crystals are suspended in 300 ml of acetonitrile and heated to reflux for 30 minutes. After cooling, the crystals are filtered off and air dried to obtain 12.2 g of the dicyclohexylamine salt of Examples 3 and 5.

[α] _D = -24.5 ° (C = 1.0, MeOH)

Example 5

N- [3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

5.98 g of N-cyclohexanecarbonyl-D-alanine is dissolved in 80 ml of dry tetrahydrofuran and 5.84 g of carbonyldiimidazole are added with stirring at -18 ° C under ice cooling. After stirring at the same temperature for about 1 hour, 6.29 g of N- (3-mercapto-2-D-methylpropanoyl) -L-proline was added, stirred for 30 minutes, and further stirred at room temperature for 1 hour. After completion of the reaction, the mixture was concentrated under reduced pressure, the solvent was distilled off, 50 ml of water was added to the residue, and the mixture was extracted with ethyl acetate after pH 1 ~ 2 with 2N-HCl aqueous solution. The ethyl acetate solution was washed with saturated aqueous NaCl solution, dried over MgSO _{4, and} concentrated under reduced pressure. 120 ml of acetonitrile is added to the obtained residue and dissolved, and 6 ml of dicyclohexylamine (DCHA) is added thereto, followed by stirring at room temperature for 1 hour. After standing overnight, the precipitate is filtered off and air dried to yield 14.35 g of crude DCHA salt. The crude DCHA salt is suspended in 300 ml of acetonitrile, heated to reflux for 30 minutes, cooled, filtered, and air dried to yield 12.20 g of a white DCHA salt. 12.20 g of DCHA salt is suspended in 90 ml of ethyl acetate, and 60 ml of 0.5N KHSO ₄ aqueous solution is added and shaken. The organic layer was washed with distilled water, dried over MgSO _{4, and} concentrated under reduced pressure to obtain 8.64 g of the title compound as a rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 6

N- [3- (N-cyclohexanecarbonylglyciylthio) -2-D-methylpropanoyl] -L-proline

1.02 g of N-cyclohexanecarbonyl-glycine is dissolved in 10 ml of dry tetrahydrofuran and 20 ml of dry tetrahydrofuran solution containing 1.07 g of carbonyldiimidazole is added with stirring at -20 ° C under ice-cooling. After stirring for 1 hour at the same temperature, 6 ml of dry tetrahydrofuran solution of 1.09 g of N- (3-mercapto-2-D-methylpropanoyl) -L-proline was added thereto, followed by 30 minutes at -20 ° C for 1 hour at room temperature. Stir. After completion of the reaction, the mixture was concentrated under reduced pressure, and the solvent was distilled off. The residue was eluted with a mixture of methanol and chloroform (1: 100-3: 100) in column chromatography using silica gel (2cm × 35cm). Fractions containing the desired product are collected and concentrated under reduced pressure to obtain 1.16 g of the title compound (rubber). This material was confirmed to be the same by the Rf of NMR and TLC.

Example 7

N- [3- (N-cyclopropanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

635 mg of N-cyclopropanecarbonyl-D-alanine and 0.70 ml of triethylamine were dissolved in 14 ml of dry tetrahydrofuran solution, 0.48 ml of chloroformic acid ethyl ester was added while stirring at -15 ° C under ice-cooling, and stirred for 15 minutes while maintaining the temperature. Then, 1.09 g of N- (3-mercapto-2-D-methylpropanoyl) -L-proline and 0.7 ml of dry tetrahydrofuran solution of 0.70 ml of triethylamine were added. After stirring for 15 minutes at the same temperature, the mixture is further stirred at 5 ° C overnight. After completion of the reaction, the reaction mixture was concentrated under reduced pressure at 30-35 ° C., and the solvent was distilled off, and 10 ml of water was added to the residue. The chloroform solution is washed with saturated aqueous NaCl solution, dried over MgSO _{4, and} concentrated under reduced pressure. The residue is eluted with silica gel column chromatography (2 cm x 35 cm) with a mixture of chloroform (1: 100-3: 100). Collect the fractions containing the desired product and concentrate under reduced pressure to give 395 mg of the title compound (rubber).

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 8

N- [3- (N-cyclohexanecarbonyl-N-methylglyciylthio) -2-D-methylpropanoyl] -L-proline

In Example 6, instead of N-cyclohexanecarbonyl-glycine, 1.09 g of N-cyclohexanecarbonyl-N-methylglycine, 1.09 g of carbonyldiimidazole, and N- (3-melcapto-2-D-methyl The same procedure as in Example 6 was carried out using 1.09 g of propanoyl) -L-proline to obtain 0.76 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 9

N- [3- (N-cyclopropanecarbonylglyciylthio) -2-D-methylpropanoyl] -L-proline

0.96 g of N-cyclopropanecarbonylglycine, 1.09 g of carbonyldiimidazole and N- (2-melcapto-2-D-methylpropanoyl) instead of N-cyclohexanecarbonyl-glycine for Example 6 The same procedure as in Example 6 was carried out using 1.09 g of -L-proline to obtain 0.4 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 10

N- [3- (N-adamantanecarbonylglylthio) -2-D-methylpropanoyl] -L-proline

1.42 g of N-adamantanecarbonylglycine, 1.09 g of carbonyldiimidazole and N- (3-melcapto-2-D-methylpropanoyl instead of N-cyclohexanecarbonyl-glycine for Example 6 1.09 g of) -L-proline was used in the same manner as in Example 6 to obtain 1.07 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 11

N- [3- (N-cyclohexanecarbonyl-D-phenylalanylthio) -2-D-methylpropanoyl] -L-proline

In Example 6, instead of N-cyclohexanecarbonyl-glycine, 1.54 g of N-cyclohexanecarbonyl-D-phenylalanine, 1.09 g of carbonyldiimidazole, and N- (3-melcapto-2-D-methylpro Panoyl) -L-proline was used in the same manner as in Example 6 using 1.09 to obtain 0.97 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 12

N- [3- (N-cyclohexanecarbonyl-D-loylsilthio) -2-D-methylpropanoyl] -L-proline

1.20 g of N-cyclohexanecarbonyl-D-leucine, 0.97 g of carbonyldiimidazole and N- (3-melcapto-2-D-methylprop instead of N-cyclohexanecarbonyl-glycine for Example 6 The same procedure as in Example 6 was carried out using 0.98 g of panoyl) -L-proline to obtain 1.17 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 13

N- [3- (N-cyclohexanecarbonyl-D-tryptiphylthio) -2-D-methylpropanoyl] -L-proline

In Example 6, instead of N-cyclohexanecarbonyl-glycine, 1.75 g of N-cyclohexanecarbonyl-D-tryptophan, 1.09 g of carbonyldiimidazole, and N- (3-melcapto-2-D-methylpro The same procedure as in Example 6 was carried out using 1.09 g of panoyl) -L-proline to obtain 0.8 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 14

N- [3- (N-cyclohexanecarbonyl-D-phenylglyciylthio) -2-D-methylpropanoyl] -L-proline

1.30 g of N-cyclohexanecarbonyl-D-phenylglycine, 0.97 g of carbonyldiimidazole and N- (3-melcapto-2-D-methyl instead of N-cyclohexanecarbonyl-glycine for Example 6 The same procedure as in Example 6 was carried out using 0.98 g of propanoyl) -L-proline to obtain 0.35 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 15

N- [3- (N-cyclohexanecarbonyl-D-methionylthio) -2-D-methylpropanoyl] -L-proline

1.30 g of N-cyclohexanecarbonyl-D-methionyl, 1.09 g of carbonyldiimidazole and N- (3-melcapto-2-D-methyl instead of N-cyclohexanecarbonyl-glycine for Example 6 The same procedure as in Example 6 was carried out using 1.09 g of propanoyl) -L-proline to obtain 0.59 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 16

N- [3- (N-cyclohexanecarbonyl-D-glutaminylthio) -2-D-methylpropanoyl] -D-proline

0.5 g of N-cyclohexanecarbonyl-D-glutamine, 0.41 g of carbonyldiimidazole and N- (3-melcapto-2-D-metalprop instead of N-cyclohexanecarbonyl-glycine for Example 6 0.41 g of panoyl) -L-proline was used in the same manner as in Example 6 to obtain 0.3 g of the title compound in the form of rubber.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 17

N- [3- (N-adamantanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline

1.2 g of N-adamantanecarbonyl-D-alanine and 0.97 g of carbonyldiimidazole and N- (3-melcapto-2-D-methyl instead of N-cyclohexanecarbonyl-glycine for Example 6 Treatment with 0.98 g of propanoyl) -L-proline in the same manner as in Example 6 to obtain 1.02 g of the rubbery title compound.

This material was confirmed to be the same by the Rf of NMR and TLC.

Example 18

N- [3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-prolinedicyclohexylamine salt

(1) 241 g of 3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoic acid was suspended in 1.3 l of dry dichloromethane, and then 117 ml of triethylamine was added at -15 ° C under stirring. Subsequently, 104 ml of pivaloyl chloride is added dropwise at −5 ° C. or lower and stirred for a further 30 minutes.

(2) 101 g of L-proline was suspended in 1.2 l of dry dichloromethane, followed by stirring to add 112 ml of trimethylsilyl chloride at -15 ° C, and then 122 ml of triethylamine at -5 ° C or lower, followed by stirring at -15 ° C for 30 minutes. do. The solution obtained in (1) is added to this solution, and the mixture is stirred for 15 minutes at room temperature under cooling for 1 hour. After the reaction was completed, 1 l of cold distilled water was added under cooling, 90 ml of concentrated hydrochloric acid was added dropwise, and the organic layer was separated after stirring for 10 minutes. The organic layer is washed twice with saturated brine and dried over magnesium sulfate. 326 ml of dicyclohexylamine and 800 ml of acetonitrile were added to the filtrate, stirred for 30 minutes, and then 800 ml of acetonitrile was added four more times at 10-minute intervals and allowed to stand overnight at 5 ° C. The precipitate is filtered off and air dried to obtain the crude compound indicated. The crude compound was dissolved by heating in 3 l of dichloromethane, and then filtered. The filtrate was stirred at room temperature for 30 minutes, and then 750 ml of acetonitrile was added four times at 10 minute intervals and left overnight at 5 ° C. The precipitate is filtered off and air dried to yield 404 g of a colorless title compound. Melting Point 190 ~ 191 ℃

[α] _D = -24.5 ° (C = 1.0, MeOH)

Example 19

N- [3- (N-cyclohexanecarbonyl-D-alanylthio) -2-D-methylpropanoyl] -L-proline calcium salt

404 g of the dicyclohexylamine salt obtained in Example 18 are suspended in 2 l of ethyl acetate, and then 2.5 l of 0.5N KHSO ₄ is added under stirring and stirred for 10 minutes. The organic layer is aliquoted, washed with distilled water and dried over magnesium sulfate. The filtrate was concentrated under reduced pressure and 1.2l of acetone was added to the resulting residue to dissolve. 1.2l of distilled water and 36.6g of calcium carbonate were added to the acetone solution, and the mixture was stirred vigorously at a bath temperature of 40 ° C. After cooling, the filtrate was concentrated under reduced pressure. 1 L of acetone is added to the obtained residue and stirred for 5 hours. The precipitate is filtered off and dried under reduced pressure after air drying to give 212 g of a colorless powder of the title compound.

[α] _D = -47.2 ° (C = 1.0, MeOH)

Claims (5)

General formula

(Ⅰ) Wherein R is an acyl group bonded to an α-amino acid group of an amino acid selected from the group consisting of cyclopropanecarbonyl, cyclohexanecarbonyl and adamantanecarbonyl groups, and A is a residue of glycine, salcosine or α-D-amino acid And its α-carbonyl group form a thiol ester bond with a sulfur atom.), Or a pharmaceutically acceptable salt thereof.

(Ⅱ) (Wherein A 'is a glycine salcosine or, optionally, an α-D-amino acid residue having a protecting group, and R has the same meaning as above).

(Ⅲ) A compound represented by (wherein R 'represents a protecting group of a hydrogen atom or a carboxyl group) or a reactive derivative thereof is reacted at -50 to 20 ° C in an inert organic solvent, and then desorbed when a protecting group is present in the reaction product. Production of a proline derivative or a pharmaceutically acceptable salt thereof. 2. The preparation of a proline derivative or a pharmaceutically acceptable salt thereof according to claim 1, wherein the reactive derivative of the compound represented by formula (II) is an active amide, an acid halide, an active ester or a mixed acid anhydride. The proline derivative according to claim 1 or a pharmaceutically acceptable compound thereof, which is reacted with a compound represented by the general formula (III) or a reactive derivative thereof in the presence of the compound carbodiimide represented by the general formula (II). Preparation of a proline derivative or a pharmaceutically acceptable salt thereof. The method for preparing a proline derivative or a pharmaceutically acceptable salt thereof according to claim 1, wherein the reactive derivative of the compound represented by formula (III) is a compound having a silyl group introduced therein. 2. The preparation of a proline derivative or a pharmaceutically acceptable salt thereof according to claim 1, wherein the inert organic solvent is tetrahydrofuran, dioxane, dimethylformamide, hexamethylphosphotriamide, chloroform, dichloromethane or acetonitrile.