JPS6318599B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides novel and useful proline derivatives having antihypertensive effects, more specifically, compounds of the general formula () (In the formula, R ₁ means a lower alkyl group.) 1-(3-lower alkanoylthio-
This invention relates to a method for producing 2-methylpropanoyl)prolylphenylalanine. The lower alkyl group represented by R ₁ in the above formula () means a linear or branched alkyl group having 1 to 6 carbon atoms, such as a methyl group,
Examples include ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, and hexyl group. Since the compound of formula () has 3 asymmetric carbon atoms, 8 stereoisomers exist. The compounds of the present invention include these stereoisomers and mixtures thereof, but the configuration of the methyl group at the 2-position of the 3-lower alkanoylthio-2-methylpropanoyl group is D type, and proline and fluorine are present. An isomer in which the enylalanine moiety has an L configuration is preferred. Recently, Cushman et al. synthesized various mercaptoalkanoyl amino acids and examined their angiotensin I convertase inhibitory activity in vitro.
Methylpropanoyl)-L-proline (SQ-
14225) is reported to be particularly effective [Bioche-mistry 16 , 5484 (1977)]. Furthermore, SQ―
It has been reported that 14225 exhibits excellent angiotensin converting enzyme inhibitory effects in vivo, and also exhibits excellent antihypertensive effects based on this inhibitory effect in experimental hypertensive animals [Science
196, 441 (1977)]. JP-A-52-116457 discloses SQ-14225 and related compounds. As a result of extensive research, the inventors have discovered that SQ-
The mercapto group of 14225 is lower alkanoylated,
It was discovered that by converting the carboxyl group of the proline moiety into an amide bond with phenylalanine, a compound with a milder antihypertensive effect and a longer duration of action than SQ-14225 could be obtained, and the present invention completed. The compound of formula () and its physiologically acceptable salts have an excellent antihypertensive effect mainly based on angiotensin converting enzyme inhibitory effect,
Can be useful as an antihypertensive agent. Since its onset of action is mild and its antihypertensive effect lasts for a long time, a stable reduction in blood pressure can be expected, and it is considered to be extremely useful in clinical applications. In other words, it is expected to eliminate the clinical inconvenience caused by a rapid drop in blood pressure and to reduce the number of doses taken. According to the invention, the general formula () (In the formula, R ₁ means the same as above.) A compound represented by or a reactive derivative thereof in the carboxyl group and the general formula () (In the formula, R ₂ means a hydrogen atom or a tert-butyl group.) When R ₂ is a tert-butyl group, the group present in the product is removed. If the product is present as a mixture of stereoisomers, the compound of formula () can be obtained by optionally separating it into individual isomers. The reaction of the compound of formula () or its reactive derivative at the carboxyl group with the compound of formula () can be carried out according to methods known in the art of peptide synthesis. This reaction is usually carried out in a solvent. The solvent used should be appropriately selected depending on the type of raw material compound, etc., and examples thereof include tetrahydrofuran, chloroform, dichloromethane, ethyl acetate, acetone, dimethylformamide, dimethylsulfoxide, pyridine, and water. Each of these solvents, alone,
Moreover, two or more kinds can be mixed and used. This reaction is carried out in the presence of a base if necessary. Specific examples of bases include alkali bicarbonates such as sodium bicarbonate and potassium bicarbonate, alkali carbonates such as sodium carbonate and potassium carbonate, and sodium hydroxide. ，
Alkali hydroxides such as potassium hydroxide or triethylamine, tri-n-butylamine, N
- Examples include organic bases such as methylmorpholine and dicyclohexylamine. The compound of formula () can also be used in the form of an acid addition salt; in this case, the free form of the compound of formula () can be produced by adding an equivalent amount of the base to the reaction system. The reaction temperature varies depending on the type of raw material compound used, but is usually in the range of about -50°C to about 60°C. When the compound of formula () is reacted as such with the compound of formula (), it is advantageously carried out in the presence of a condensing agent such as dicyclohexylcarbodiimide, N,N'-carbonyldiimidazole. Furthermore, the reactive derivatives at the carboxyl group of the compound of formula () include reactive derivatives commonly used in the field of peptide synthesis. Specific examples include acid halides (particularly acid chlorides), mixed acid anhydrides, active esters, symmetrical anhydrides, and acid amide, with the former three being particularly preferred. The removal of the tert-butyl group optionally present in the compound obtained by the above method can be carried out according to a conventional method, for example, by treating the product with trifluoroacetic acid and anisole, the corresponding carboxylic acid can be easily removed. derivatives can be derived. The compound of formula () produced by the above reaction is
It can be isolated and purified by conventional methods such as extraction, chromatography, and recrystallization. The starting compound () or () in the above production method may be a racemate or a stereoisomer. but,
In order to obtain the desired stereoisomer, it is desirable that the configuration of the proline and phenylalanine moieties in the starting compound () correspond to that of the target compound. The configuration of the methyl group at the 2-position of the 3-lower alkanoylthio-2-methylpropanoyl group in the starting compound () may be DL type. When using the DL type, stereoisomers in the product can be separated by conventional methods such as chromatography and fractional recrystallization. The compound of formula () can be converted into salts by treatment with various physiologically acceptable inorganic or organic bases according to conventional methods. Examples of these salts include alkali metal salts (eg, sodium salts, potassium salts), alkaline earth metal salts (eg, calcium salts, magnesium salts), ammonium salts, benzathine salts, hydrabamine salts, and lysine salts. Below, representative compounds of the present invention, 1-(D
-3-acetylthio-2-methylpropanoyl)
-L-prolyl-L-phenylalanine (hereinafter referred to as
It is written as compound A. ) and 1-(D-3-propanoylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine (hereinafter referred to as compound B
It is written as ) and the results of testing the antihypertensive effects of SQ-14225. One group of 5 male STD Wistar rats, 8 weeks old, were used as experimental animals. A silver clip (inner diameter 0.20 mm) was attached to the left renal artery of each rat under ether anesthesia.
The right kidney and renal artery were left intact, and tap water was given as drinking water. Rats treated in this way are usually treated with a direnal Goldblatt with renal hypertension.
This type of rat is thought to have curved renin-angiotensin-dependent hypertension. Blood pressure was 190 10 to 21 days after wearing the clip.
At ~220 mmHg, compounds A, B and SQ-
14225 was orally administered once at 0.1 mmol/Kg each.
Blood pressure was measured over time. Measuring blood pressure with tail
Plethysmograph method (tail)
It was performed non-invasively under anesthesia using the plethysmographic method. The figure shows changes in blood pressure over time. As is clear from the figure, the antihypertensive effects of Compounds A and B are not only expressed more slowly than SQ-14225, but also have a longer duration of action than SQ-14225.
-It is considerably longer than 14225. As described above, the compound of formula () and its physiologically acceptable salts exhibit excellent antihypertensive effects and can be used as antihypertensive agents for the treatment of hypertension. In particular, it is useful for treating hypertension caused by enhancement of the renin-angiotensin system.
Its administration forms include oral administration, parenteral administration,
Although either rectal administration is acceptable, oral administration is preferred. The dosage of the compound of the present invention varies depending on the type of compound, administration method, patient's symptoms, age, etc., but is approximately 0.1 to 200 mg/Kg/day, preferably 0.2 to 50 mg/Kg/day.
mg/Kg/day. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. Reference Example 1 3-Propanoylthio-2-methylpropanoic acid A mixture of 50 g of thiopropanoic acid and 34.1 g of methacrylic acid was heated on a boiling water bath for 3 hours, and then left overnight at room temperature. The reaction mixture was distilled under reduced pressure to a boiling point of 135
The target compound is obtained by separating the fraction at ~138°C (2 mmHg). Reference example 2 3-propanoylthio-2-methylpropanoic acid chloride 3-propanoylthio-2-methylpropanoic acid
Mix 19.7 g and 16 g of thionyl chloride and stir at room temperature overnight. The reaction mixture was distilled under reduced pressure and the boiling point
The target compound is obtained by separating the fraction at 135-137°C (35 mmHg). Example 1 1-(D-3-acetylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine L-prolyl-L-phenylalanine tert-
Dissolve 1.0 g of butyl ester in dichloromethane. This solution was cooled to around -30°C, 0.32 g of N-methylmorpholine was added with stirring, and then 3
-Acetylthio-2-methylpropanoyl chloride
Drop 0.57g. After stirring for 30 minutes, stir for an additional hour at room temperature. The reaction solution was washed successively with 4% sodium bicarbonate, water, 10% citric acid, and water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography and eluted with chloroform to obtain 1-(3-acetylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine tert-butyl ester. This is dissolved in a mixed solution of 10 ml of anisole and 20 ml of trifluoroacetic acid, and left at room temperature for 1 hour. The reaction solution was concentrated to dryness under reduced pressure. Dissolve the residue in a small amount of ethanol,
Add an appropriate amount of n-hexane and leave to stand. The precipitated crystals are taken and recrystallized repeatedly from a mixed solvent of ethanol and n-hexane to obtain the target compound.
Melting point 155-156℃ [α] ²⁵ _D = -81.3゜ (c = 1.02, ethanol) IR ν ^KBr _nax cm ^-1 : 3240, 1740, 1685, 1645, 1620 Example 2 1-(D-3-acetylthio- 2-Methylpropanoyl)-L-prolyl-L-phenylalanine 0.52g of L-prolyl-L-phenylalanine
Dissolve in 2 ml of 1N sodium hydroxide. Add 0.36 g of 3-acetylthio-2-methylpropanoyl chloride to this solution while stirring vigorously under ice cooling.
Add 1 ml of 2N sodium hydroxide. After stirring the solution for 3 hours at room temperature, it is washed with ether, acidified and extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and then concentrated to dryness under reduced pressure. Dissolve the residue in a small amount of ethanol, add an appropriate amount of n-hexane, and leave to stand. The precipitated crystals are taken and recrystallized repeatedly from a mixed solvent of ethanol and n-hexane to obtain the target compound. Example 3 1-(D-3-propanoylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine L-prolyl-L-phenylalanine tert-
Dissolve 0.70 g of butyl ester in dichloromethane. This solution was cooled to around -30°C, 0.22 g of N-methylmorpholine was added with stirring, and then 3
-Drop 0.43 g of propanoylthio-2-methylpropanoyl chloride. After stirring for 30 minutes, stir for an additional hour at room temperature. The reaction solution was washed successively with 4% sodium bicarbonate, water, 10% citric acid, and water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography and eluted with chloroform to obtain 1-(3-propanoylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine tert-butyl ester. This ester is dissolved in a mixed solution of 10 ml of anisole and 20 ml of trifluoroacetic acid and left at room temperature for 1 hour. The reaction solution was concentrated to dryness under reduced pressure, and the residue was subjected to silica gel column chromatography and eluted with chloroform-methanol (98:2) to obtain 1-
(3-propanoylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine is obtained. Dissolve this in an appropriate amount of diethyl ether, add seeds of the target compound, and leave in the refrigerator. The precipitated crystals are collected and recrystallized repeatedly from a mixed solvent of diethyl ether and petroleum ether to obtain the target compound. Melting point 107-140℃ [α] ²⁰ _D = -81.1゜ (c = 1.00, ethanol) IR ν ^KBr _nax cm ^-1 : 3220, 1730, 1670, 1635, 1610 Example 4 1-(D-3-propanoylthio- 2-Methylpropanoyl)-L-prolyl-L-phenylalanine 3-propanoylthio-2-methylpropanoic acid
0.30g and dicyclohexylcarbodiimide 0.35g
was dissolved in 10 ml of dichloromethane, 0.54 g of L-prolyl-L-phenylalanine tert-butyl ester was added thereto, stirred for 1 hour on an ice-water bath, and then further stirred at room temperature overnight. The reaction solution was concentrated under reduced pressure, ethyl acetate was added to the residue, and after cooling, the precipitated crystals were removed. 4% sodium bicarbonate solution,
Wash sequentially with water, 10% citric acid, and water, dry over anhydrous sodium sulfate, and concentrate under reduced pressure. The residue was subjected to silica gel column chromatography and eluted with chloroform to give 1-(3-propanoylthio-2-methylpropanoyl)-L-prolyl-L.
-Phenylalanine tert-butyl ester is obtained. This ester is reacted and treated in the same manner as in the third paragraph of Example 3 to obtain the target compound.

[Brief explanation of the drawing]

The drawing shows compound A(1), compound B(2) and SQ―
14 is a graph showing changes in blood pressure over time when 14225(3) was administered to direnal Goldblatt rats with renal hypertension. Each point represents the average value, and the vertical line represents the average error.

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ means a lower alkyl group.) The compound represented by or its reactive derivative in the carboxyl group and the general formula (In the formula, R ₂ means a hydrogen atom or a tert-butyl group.) When R ₂ is a tert-butyl group, the group present in the product is removed. and, if the product is present as a mixture of stereoisomers, optionally separating it into individual isomers. (In the formula, R ₁ means the same as defined above.) 1-(3-lower alkanoylthio-
2-Methylpropanoyl)prolylphenylalanine production method.