SE431643B - THERAPEUTICALLY ACTIVE HALOGEN-SUBSTITUTED PROLINE DERIVATIVES CONTAINING SULFUR AND PROCEDURE FOR THEIR PRODUCTION - Google Patents

Description

The L-configuration of the proline group is particularly preferred.

The lower alkyl groups represented by Any of the variables include straight and branched chain hydrocarbon groups from methyl to heptyl, for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl and the like. The C1-C4 groups, especially the C1 and C2 groups, are preferred.

The lower alkanoyl groups are the acyl groups of the lower (C 2 -C 7) fatty acids, for example acetyl, propionyl, butyryl and the like. Likewise, these lower alkanoyl groups have up to 4 carbon atoms and especially acetyl is preferred.

The halogens are the four common halogens, with chlorine, bromine and fluorine being preferred, especially fluorine.

The products of formula I can be prepared via various synthetic methods.

In general, these compounds can be synthesized by coupling the acid of formula (II) e Ra Ta R - s - (CH) 5-cH coon to the amino acid of formula _ RR '(III) 2 2 X / ///' c \ \\\ H2? CF2 HN than cooR1 by any method that can be used to form amide bonds. See, for example, "Methoden der Organischen Chemie", (Houben-Weyl), Part I, p. 376 et seq., Part III, p. 1 et seq. (1974) 7901510-3 The acids of formula 11, wherein n is l can is obtained by adding a thioacid R-SH to an appropriately substituted acrylic acid.

As the temporary protection of the mercapto group in the compounds of formula II, R may be a p-methoxybenzyl group. This group is then removed with trifluoroacetic acid and mercury acetate.

The acids of formula II, wherein n is 0, are obtained by an exchange reaction using a thioacid R-SH and a 2-halogen acid.

When R 7 is lower alkyl, to give a product of the formula VR: R 12 R 1 * h C [than I4 V3 3. 2 = L alkyl -co-s- (cH> -¿-c. ~; -Co-N cooal, the product can be transferred to the product 1 Rz R 2 vr R4 1813 Hzfl1 CH 2 Hs-- (CH) n- c1z- co -NC °° R1 by conventional alkaline hydrolysis or ammonolysis, when R1 is an ester group (ie R1 is lower alkyl, obtained when an ester of the starting acid V is used), the ester group can be removed in a known manner For example, when R1 is tert-butoxy or tert-amyloxy, treatment of the ester of formula V or VI with trifluoroacetic acid and anisole corresponding to free When other alkoxy groups are present, alkaline hydrolysis gives the corresponding acid.

When an acid of formula II is used as starting material or when the final product is obtained in the form of the free carbonic acid, this acid can be converted to its ester, for example by esterification with a diazoalkane, such as diazomethane, 1-alkyl-3-p-tolyl -triazen, such as 1n-butyl-3-p-tolyltriazine and the like. In a variation of the process, an ester, preferably the methyl or t-butyl ester of formula V, is treated in an anhydrous medium such as dichloromethane, tetrahydrofuran, dioxane or the like with an acylthioalkanoic acid of formula Ra TB alkyl - C0-5- ( CH 2 -CGOH in the presence of dicyclohexylcarbodiimide, N, N'-carbonylbisimidazole, ethoxyacetylene, diphenylphosphoryl azide or similar coupling agents at a temperature in the range of about 0-10 ° C. The ester group can then be removed, for example by treatment with trifluoroacetic acid and anisole at approximately room temperature to give the free acid (R1 = H).

One way, preferably when n is 1, R is CF 3 and R 3 is H, is to react a thioacid of the formula alkyl-COSH with an acrylic acid derivative of the formula VIII R2 // R R4 R3 O in I 'I H2' CHR6) m ca ec fl- c ~ ._ N _-- L ~ cooRl and then continue as above. The compounds of the formula Valkyl are obtained from 3-trifluoromethylacrylic acid and an ester of the formula / formula according to the method described in Example 79g1510-3. Halogenated compounds of the formula V which are used as starting materials can be prepared according to known methods, for example Biochemistry 3, 2509 (Aust. . J. Chem. 29, 1493 (1967), J. Amer. Chem. Soc. §§, 4709 (1964), J. Med. Chem. gg, ll76 (1977).

The products of formula I have one or more asymmetric Centraq, the basic being indicated down an asterisk in the formula I.

The compounds thus exist in stereoisomeric forms or in racemic mixtures thereof. All are within the scope of the invention. The syntheses described above may use the crude material or one of the enantiomers as starting material. When the racemic starting material is used in the synthesis process, the resulting stereoisomers can be separated by conventional chromatographic or fractional crystallization methods. In general, the L-isomer with respect to the basic asymmetric carbon atom is the preferred isomeric form.

The compounds according to the invention form basic salts with various inorganic or organic bases, which is also within the scope of the invention. Such salts include ammonium salts, alkali metal salts, such as sodium and potassium salts (which are preferred), alkaline earth metal salts, such as calcium and magnesium salts, salts with organic bases, e.g. dicyclohexylamine salts, benzatin, N-methyl-D-glucamine, hydrabamine salts, salts with amino acids such as arginine, lysine and the like. The non-toxic, physiologically acceptable salts are preferred, although other salts are also useful, e.g. when isolating and purifying the product.

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

Further experimental details are described in the examples, which constitute preferred embodiments and also serve as models for the production of other members of the group.

The compounds of the invention are useful as hypotensive agents. They prevent the conversion of the decapeptide angiotensin I to angiotensin II and are therefore useful for the reduction or alleviation of angiotensin-dependent hypertension. The action of the enzyme renin on angiotensinogen, a pseudoglobulin in blood plasma, produces angiotensin I. Angiotensin I is converted by angiogenesis-converting enzyme (ACE) to angiotensin II. The latter is an active compressor substance, which has been considered to be the causative agent of violet forms of hypertension in various mammalian species, such as rats and dogs. The compounds of the invention intervene in the angiotensinogen-9 (renin) syangiotensin I-a (ACE) -9 angiotensin II sequence by preventing the angiotensin converting enzyme and by reducing or eliminating the formation of the pressor substance angiotensin II. Thus, when administering a composition containing one or a combination of compounds of formula I or a physiologically acceptable salt thereof, angiotensin-dependent hypertension is alleviated in mammalian species suffering therefrom. A single dose, or preferably two to four divided daily doses, prepared on the basis of about 0.1 to 100 mg / kg / day, preferably about 1-50 mg / kg / day, is suitable for reducing blood pressure as shown in the animal experiments described. of SL Engel, T.R. Schaeffer, M.H. Waugh and B. Rubin, Proc.

Soc. Exp. Biol. With. lay; (1973). The substance is preferably administered orally, but parenteral administration, such as subcutaneous, intramuscular, intravenous or intraperitoneal, may also be used. The compounds of the invention may be used to effect a reduction in blood pressure by the preparation of compositions, such as in the form of tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral administration. Approximately 10-500 mg of a compound or mixture of compounds of formula I, or their physiologically acceptable salts, are mixed with a physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizing agent, flavoring agent, etc. in a unit dosage form according to the usual pharmaceutical practice. The amount of active substance in these compositions or preparations is such that a suitable dose is obtained within the stated range.

Examples of adjuvants which may be incorporated into the tablets, capsules or the like are as follows: a binder such as gum tragacanth, acacia, corn starch or gelatin; an excipient such as dicaloium phosphate or microcrystalline cellulose; a disintegrant such as corn starch, note starch, alginic acid or the like, a lubricant such as magnesium stearate; a sweetener such as sucrose, lactose or saccharin; a flavoring agent, such as peppermint, oil of evergreens or cherries. When the dosage unit form is a capsule, it may contain, in addition to the above-mentioned materials, a liquid carrier, such as a fatty oil. Various other materials may be present as coating materials or to otherwise modify the physical form of the dosage unit. For example, the tablets may be coated with shellac, sugar or both. A syrup or elixir may contain the active compound, sucrose as a sweetening agent, methyl and propyl parabens as a preservative, a coloring and flavoring agent such as cherry or orange flavor.

Sterile compositions for injection can be prepared according to conventional pharmaceutical practice by dissolving or suspending the active substance in a vehicle, such as water for injection, a naturally occurring vegetable oil, such as soybean oil, coconut oil, peanut oil, cottonseed oil, etc. The invention is further illustrated by the following examples and exhibits particularly preferred embodiments. All temperatures are given in degrees Celsius.

Example 1 1- (4,4,4-Trifluoro-2-butenoyl) -L-nrolin 7.0 g (0.1 mol) of boric acid anhydride (prepared by melting boric acid in a platinum crucible and crushing under nitrogen) is combined with 32 .2 g (0.173 mol) of ethyl s-hyaroxy-z: nwl trifluorobutanoate in a 50 ml flask equipped with a Dean ~ Stark trap and the mixture is heated at 180 ° on a salt bath until all the anhydride has dissolved ( 6 hours). The heat is increased to 3500, during which time 23 ml of distillate accumulates in the trap. The distillate is returned to the reaction flask and the heating step is repeated. This process is repeated 4 times to ensure complete dehydration of the hydroxyester. The distillate is dissolved in petroleum ether, dried over phosphorus pentoxide and distilled to give 10 g of 4,4,4-trifluoro-2-butyric acid ethyl ester (b.p. 115-1200) and 650 mg of 4,4,4-trifluoro-2-butyric acid (b.p. 1500, 53-550 recrystallization from pentane).

The ester is combined with 24 ml of 10% sodium hydroxide in water and stirred at 250 for 6 hours. The mixture is diluted with water and extracted with methylene chloride to remove unreacted material. The aqueous layer was adjusted to pH 3 with concentrated hydrochloric acid and the mixture was extracted with 3 x 50 ml of methylene chloride. The organic layers were combined, dried over sodium sulfate, concentrated and the residue distilled to give crystalline 4,4,4-trifluoro-2-butyric acid (b.p. 145-1530). Recrystallized from pentane, the acid melts at 54-55 ° C, yield 4.6 g.

A mixture of 4.91 g (35 mmol) of 4,4,4-trifluoro-2-butyric acid, 4.73 g (35 mmol) of hydroxybenzotriazole, 6.00 g (35 mmol) of L-proline-t-butyl ester and 7.22 g (35 mmol) of dicyclohexylcarbodiimide in 200 ml of methylene chloride are stirred under nitrogen overnight at room temperature. The mixture is filtered, the filtrate is washed with 2 x 50 ml of 5% sodium hydrogen sulphate and with 2 x 50 ml of saturated sodium hydrogen carbonate, dried over sodium sulphate and concentrated to give an oil. This is dissolved in ether and the solution is cooled and filtered free of precipitate. The filtrate is concentrated to give a solid (m.p. 95 DEG-10 DEG C., 3.7 g), which according to TLC (silica gel EM 50/50, EtOAc / CH2Cl spot. 2, PF = 0.85) shows a single mixture of the above-obtained 1- (4,4,4-trifluoro-2-butenoyl) -L-proline-t-butyl ester (4.0 g, 13.6 mmol) is mixed with 60 ml of trifluoroacetic acid and 13 ml of anisole and stirred under a nitrogen curtain for an hour. The solvents are removed in vacuo and the residue, dissolved in 10 ml of ether, is poured into 500 ml of pentane. This precipitation procedure is repeated and the residue is allowed to stand at 0 ° C for 72 hours, during which time crystallization occurs. 1- (4,4,4-Trifluoro-2-butenoyl) -L-proline is recrystallized from ethyl acetate / hexane; yield 2.48 g, melting point 119 ~ 120 °.

Example gel 2- (1- (3-mercapto-4,4,4-trifluorobutanoyl) -L-nrolin 1.5 ml thiolacetic acid is combined with 720 mg (3 mmol) 1- (4,4,4-trifluoro-2-butenoyl) -L-proline under argon and the mixture is stirred at room temperature overnight. the excess thiolacetic acid is removed in vacuo and the remaining 1- (3-acetylthio-4,4,4-trifluorobutanoyl) -L-proline is mixed with aqueous ammonia (15 ml concentrated NH 3 + 15 ml water) and stirred for 2 hours at room temperature. The mixture is then diluted with ice and acidified with concentrated hydrochloric acid. The acidic mixture is extracted with 3 x 50 ml of methylene chloride, the extracts are dried over sodium sulphate and concentrated to an oil. This is purified by dissolving in water (distilled twice), treating the solution with carbon and filtering through a millipore filter (0.4 m followed by 0.08 m). Lyophilization of the solution gives 700 mg of 1- (3-mercapto--4,4,4-trifluorobutanoyl) -L-proline in the form of a colorless glass.

Rf (benzene: acetic acid 7: 1) 0.24. 7901510-3 10 Exemgel 3.

Cis-1- [D-3- (acetylthio) -2-methyldropanoyl] -4-fluoro-L-proline 4.5 g (0.02l mol) of cis-4-fluoro-L-proline hydrobromide and 4.2 g (0.023 mol) of D-3-acetylthio-2-methylpropanoic acid chloride is allowed to react in 50 ml of water in the presence of sodium carbonate to stabilize the pH at 8.0-8.2 during the acylation (about 20 minutes). The mixture is worked up after a further hour by washing with 2 x 50 ml of ethyl acetate, supernatant with ethyl acetate, acidified with hydrochloric acid to pH 2, saturated with sodium chloride and the layers separated. The aqueous phase is extracted with additional ethyl acetate and the organic layers are combined, dried and evaporated. The solid residue from the ethyl acetate evaporation is rubbed with ether and the evaporation is repeated; weight of the colorless product, 5.4 g (93%), melting point 146-14s ° <5. 33 °), [α] 26 -1320 (c = 1, methanol). The dicyclohexylamine salt is prepared V D by adding dicyclohexylamine to cis-1- [D-3- (acetylthio) -7-2-methylpropanoyl-4-fluoro-L-proline in 70 ml of ethyl acetate. 8.1 g of the salt which crystallizes out are obtained, m.p. 202 DEG-204 DEG (S. 1a7 DEG); talšö -72 ° from 80 ml of isopropanol gives 7.0 g, m.p. 205-2070 (p. 190 °). (c = 1, methanol). Crystallization [m] š6-740. A sample recrystallized from ethanol shows no further change in the melting point of [a] D. 16.9 g of the dicyclohexylamine salt are converted back to the free acid by partitioning between 10% potassium hydrogen sulphate and ethyl acetate (60 ml of 10% KHSO 4; 4 x 50 ml of ethyl acetate extractions).

The organic layers are combined and evaporated to dryness to give 4.1 g (71%) of a colorless free acid, m.p. 154-1560 (p. 1400) [α] D 6-1420 (c = 1, methanol). 7901510-3 H Exemgel 4.

Cis-4-fluoro-1- (D-3-mercapto-2-methylneroanooyl) -L-nrolin 3.9 g (0.014 mol) cis-1- [D-3- (acetylthio) -2-methylpropanoyl] -4-fluoro-L-proline is hydrolyzed in 22 ml of water containing 9 ml of concentrated ammonium hydroxide. The reaction mixture is acidified with hydrochloric acid and extracted with ethyl acetate. The organic layer is concentrated to dryness to give 3.3 g of a glassy product, which crystallizes slowly on drying at 0.2 mm Hg and 500. The material is triturated with 20 ml of ethyl acetate (with slight heating under argon), diluted with 25 ml of hexane, rubbed and cooled overnight (under argon). After filtration under argon, washing with hexane and drying in vacuo, the colorless solid, cis-4-fluoro-1- (D-3-mercapto-2-methylpropanoyl) -L-proline, weighs 2.8 g (85%) , m.p. 135-1370 (S. 132), fdlšó -1160 (c = 1; methanol).

Example 5- 1- [3- (Acetylthio) -2-chloroprooanoyl] -L-proline (isomer A) 1.44 g of L-proline and 667 mg of sodium carbonate are dissolved in 17 ml of water and stirred on an ice bath. To this solution is added 2 g of sodium carbonate in 8.5 mg of water, and immediately thereafter 2.5 g of 3-acetylthio-2-chloropropanoic acid chloride are added. The ice bath is removed. After 30 minutes a precipitate forms which is solubilized by adding 17 ml of water. After a total period of 1.5 hours, the reaction mixture is extracted twice with ethyl acetate. The aqueous layer is cooled, acidified with concentrated hydrochloric acid, saturated with sodium chloride, extracted with ethyl acetate, dried over magnesium sulfate and concentrated to dryness in vacuo to give the product as a crude oil, yield 3.3 g.

The oil is introduced into a 100 g silica gel column and eluted with benzene / acetic acid, 7: 1, to give 2 g of the product, which crystallizes from water to give 450 mg of 1- [3- (acetylthio) -2-chloropropanoyl ] -L-proline, melting point III-1130, [α] D -1700 (c = 1; ethanol).

Example Gel 6. 1- [3- (Acetylthio) -2-chloropropanoyl] -L-proline (isomer B) The aqueous mother liquors from Example 22 are lyophilized and chromatographed on silica gel with benzene / acetic acid, 7: 1. The fractions containing UV-absorbing material, which according to TLC are found to be homogeneous, are combined, concentrated to dryness and crystallized from water, yield 800 mg, melting point 90-1090, [a] š5_-40 (c = 2 , 1; ethanol). The mother liquors are concentrated to dryness by freeze-drying and the remaining 1- [3- (acetylthio) -2-chloropropanoyl-L-proline (isomer B) is crystallized from ether / hexane; yield 380 mg, m.p. 108-1100, falâs + 17.60 (c = 1.25; ethanol).

Example 7, 1- [3- (Acetylthio) -2-bromopropanoyl] -L-proline Using the 3-acetylthio-2-bromopropanoic acid chloride: instead of 3-acetylthio-2-chloropropanoic acid chloride in the procedure of Example 5, 1- [3 - (acetylthio) -2-bromopropanoyl] -L-proline, m.p. 109 DEG-110 DEG, [.alpha.] D @ 202 DEG (c = 1.39; ethanol).

Example 8. 3- (4-Methoxybenzyl) -thio-2-trifluoromethylpropanoic acid The mixture of 3.9 g of 1-trifluoromethylacrylic acid and 4.3 g of 4-methoxybenzylthio is stirred at 100-110 ° for one hour. The mixture is allowed to cool to room temperature and the solid is recrystallized from cyclohexane, m.p. 72-740.

Example 9. 9-E3- (4-Methoxybenzyl) -thio-2-trifluoromethylpropanoyl] -L-proline-tert-butyl ester 7 A solution of 6.5 g of 3- (4-methoxybenzyl) -thio-2-trifluoromethylpropanoyl acid and 3.76 g of proline-tert-butyl ester in 500 ml of dichloromethane are stirred at 0 DEG C. and treated with 4.53 g of acyclohexylcarboyamide.

After 30 minutes at 0 DEG C. and overnight at room temperature, the mixture is filtered and the filtrate is washed until neutral. The organic layer is dried and concentrated to dryness in vacuo. TLC [silica gel methylene chloride / ethyl acetate (9515)] shows two major spots Rf 0.46 and 0.51 corresponding to the two diastereoisomers. Example 90 1- (3-mercapto-2-trifluoromethylpropanoyl)) - L-uroline A solution of 4.47 g of 1- [3- (4-methoxybenzyl) -thio-2-trifluoromethyl-propancyl] -L-proline The tert-butyl acetate of Example 37 and 10 ml of anisole are cooled to 100 DEG and 10 ml of trifluoroacetic acid are added, followed by 3.18 g of mercury acetate. The bath is removed and the mixture is stirred at room temperature for one hour.

The mixture is concentrated to dryness in vacuo and the residue is triturated with ether / hexane. The insoluble material is suspended in water and hydrogen sulfide is bubbled through for 10 minutes. The precipitate is removed by filtration and the filtrate is lyophilized to give the product, 1- (3-mercapto-2-trifluoromethylpropanoyl) -L-proline as an amorphous solid. Rf 0.29-0.31 (silica gel-benzeneacetic acid, 7: 1).

Example 11 D-3-acetylthio-2-methyloropanoic acid chloride A suspension of 150 g (690 mmol) of 1- (D-3-mercapto-2-methyl-propanoyl) -L-proline in 1274 ml of water and 426 ml of concentrated hydrochloric acid (5,526 mol) reflux under nitrogen with stirring for 8 hours. The resulting solution is kept at room temperature overnight and then extracted with 400 ml of chloroform (10 times). The combined chloroform extracts are dried over magnesium sulphate under nitrogen and then evaporated. To the residue, 81.2 g, are added 176 ml (1.809 mol) of acetic anhydride and 180 ml of pyridine and the mixture is kept at room temperature for 20 hours.

The mixture is then evaporated and the oily residue is dissolved in 1000 ml of ethyl acetate and washed successively with 200 ml of 5% hydrochloric acid / saturated sodium chloride (wash pH 2), 200 ml of saturated sodium chloride solution (2 times, pH in the second wash: 7 ) od1där ~ after the solvent is removed. To the clear oily residue, [96.9 q, 86.5%, ia] š5 = -61.80 (cHc13)] was added as ml (1.173 mol) of freshly distilled thionyl chloride and the resulting solution was stirred at room temperature with gas evolution for 18 hours. The excess thionyl chloride is evaporated in vacuo and a 500-bath and the residue is distilled under reduced pressure to give 56.9 g of D-3-acetylthio-2-methylpropanoic acid chloride, b.p. 40-44 ° <ø, 17-o, 2 mm Hg ). [α] D 25 -42.50 (C 2; methanol). 7901510-3 Example 12.

Trans-1- [D-3- (acetylthio) -2-methyl-1-oxonropyl] -4-fluoro-L-orolin A) - Trans-1-carbobenzyloxy-4-fluoro-L-proline A solution of 6.2 g of trans-1-carbobenzyloxy-4-fluoro-L-nrolin methyl ester in 50 ml of methanol are treated dropwise at 0-50 with 11.5 ml of 2N sodium hydroxide solution and after one hour at 0 DEG C. the solution is allowed to warm to room temperature overnight.

The reaction mixture is concentrated under reduced pressure to about half the original volume and then diluted with 100 ml of water. The aqueous reaction mixture is extracted with ether and the ether extracts are discarded. The aqueous solution is acidified, while cooling, with dilute hydrochloric acid to pH 2 and then extracted with ethyl acetate (4 x 50 ml). The combined ethyl acetate extracts are dried over anhydrous magnesium sulfate and then concentrated under reduced pressure to give the desired product. This is purified by transfer to the cyclohexylamine salt, m.p. 194-1960, [m] š5 -440 methanol). (c = 1% in The free acid is obtained by suspending cyclohexylamine salt in 25 ml of ethyl acetate with 22 ml of 1N hydrochloric acid and extracting the aqueous layer with 4 x 35 ml of ethyl acetate. The combined ethyl acetate extracts are dried over anhydrous magnesium sulphate and the solvent is concentrated under reduced pressure to form the desired trans-1-carbobenzyloxy-4-fluoro-L-proline.

B) Trans-4-fluoro-L-oroline hydrobromide A mixture of 3 g of trans-1-carbobenzyloxy-4-fluoro-L-proline and 15 ml of hydrogen bromide in acetic acid (30-32%) is stirred for one hour and then added 150 ml of anhydrous ether. The solvent is decanted off from the precipitate, which is then triturated with fresh ether and finally with methyl ethyl ketone. The trans-4-fluoro--L-proline hydrobromide melts at 162-1640 (decomposition), [α] -5-300 (c = 1% in methanol). C) Trans-1- [D-3- (acetylthio) -2-methyl-1-oxopropyl] -4-fluoro-L-Broline To a stirred solution of 1.9 g of trans-4-fluoro-L-proline hydro- bromide in 25 ml of cold water, add 1 g of sodium carbonate for adjustment of the pH to 8.2. Then, with continuous cooling (50) and stirring, 1.8 g of D-3-acetylthio-2-methylpropionyl chloride in 2.5 ml of ether are added dropwise, while maintaining the pH at about 8.2-8.3 by dropwise addition of a 25% aqueous sodium carbonate solution. Stirring and cooling are continued for one hour after the addition is complete.

The reaction mixture is extracted with ethyl acetate (2 x 25 ml) and the extracts are discarded. To the aqueous layer is added 50 ml of ethyl acetate, and while stirring and cooling, concentrated hydrochloric acid is added dropwise to a pH of 2.0. The aqueous layer is saturated with sodium chloride and the ethyl acetate layer is separated. The aqueous layer is extracted with additional ethyl acetate (3 x 25 mL), the combined ethyl acetate extracts are dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired product. The dicyclohexylamine salad is prepared by dissolving the product in 25 ml of ethyl acetate and adding a solution of 1.8 g of dicyclohexylamine in 35 ml of ethyl acetate. The precipitated salt is filtered and recrystallized from isopropanol to give the dicyclohexylamine salt of trans-1- [D-3- (acetylthio) -2-methyl-1-oxopropyl] -4-fluoro-L-proline; m.p.

The free acid is recovered by dissolving the dicyclohexylamine salt in 5% aqueous acidic potassium sulfate and extracting with ethyl acetate. The ethyl acetate solution is dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired trans-1- [D-3- (acetylthio) -2-methyl-1-oxopropyl] -4-fluoro-L-proline.

Example gel 13- Trans-4-fluoro-1- (D-3-mercanto-2-methyl-1-oxonronyl) -L-proline Argon is passed through a cooled solution of 4.2 ml of concentrated ammonium hydroxide in 16 ml of water. To this solution is added, with stirring in an argon atmosphere, 1.8 g of trans-1- [D-3- (acetylthio) -2-methyl-1-oxopropyl] -4-fluoro-L-proline. The reaction mixture is stirred for a further two hours and then extracted with ethyl acetate, which is then discarded. The aqueous layer is stirred, 30 ml of ethyl acetate are added and the aqueous layer is acidified with concentrated hydrochloric acid. The aqueous layer is saturated with sodium chloride 790151G-3 fe and the ethyl acetate layer is separated. The aqueous layer is extracted with ethyl acetate (3 x 30 ml). The combined ethyl acetate extracts are dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired trans-4-fluoro-1- [D--3-mercapto-2-methyl-1-oxopropyl) -L-proline; Idlâñ -112 ° (c = 1% in methanol).

Example 14-14 {D-3- (acetylthio) -2-methyl-1-oxopropyl] -4,4-difluoro-L-proline A) -1-carbobenzyloxy-4,4-difluoro-L-uroline methyl ester To a cooled stirred solution of 3.3 g of 1-carbobenzyloxy-4-keto-L-proline methyl ester in 80 ml of methylene dichloride is added dropwise to 3.3 ml of diethylamino sulfur trifluoride. The reaction mixture is allowed to remain at room temperature overnight. About 100 g of crushed ice is added with stirring and the reaction mixture is stirred for 45 minutes. The organic layer is separated and the aqueous layer is extracted with methylene chloride (2 X 40 ml). The combined extracts are dried over anhydrous magnesium sulfate and then concentrated under reduced pressure to give the desired 1-carbobenzyloxy-4,4-difluoro-L-proline methyl ester.

B) 1-Carbobenzyloxy-4,4-difluoro-L-proline I A solution of 5.6 g of 1-carbobenzyloxy-4,4-difluoro-L-proline methyl ester in 50 ml of methanol is treated dropwise with 11.5 ml of 2N sodium hydroxide solution at 0-50. The reaction mixture is left at 0 ° for one hour and then allowed to warm to room temperature overnight. The reaction mixture is concentrated under reduced pressure to about half its original volume and then diluted with 100 ml of water. The aqueous reaction mixture is extracted with ether and the ether extracts are discarded.

The aqueous solution is acidified while cooling with dilute hydrochloric acid to pH 2 and then extracted with ethyl acetate (3 x 50 ml). The ethyl acetate extracts are combined and washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated to give the desired product, 1-carbobenzyloxy-4,4-difluoro-L-proline. This is purified by conversion to the cyclohexylamine salt. melting point 150 ° -5 °, [alpha = -24 ° (c = 1 in ethanol). 7901510-3 X? The free acid is obtained by treating an aqueous solution of the cyclohexylamine salt with hydrochloric acid and extracting the mixture with ethyl acetate (4 x 30 ml). The ethyl acetate extracts are dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired 1-carbobenzyloxy-4,4-difluoro-L-proline.

C) 4,4-Difluoro-L-proline hydrobromide A mixture of 2.4 g of 1-carbobenzyloxy-4,4-difluoro-L-proline and 12 ml of hydrogen bromide in acetic acid (30-32%) is stirred for 30 minutes at room temperature and then 300 ml of anhydrous ether are added. The mixture is cooled and the precipitated solid is filtered and dried under reduced pressure. The desired 4,4-difluoro-L-proline hydrobromide melts at 163-165 ° (dec. 9); lmlšs = -140 (c = 1% in methanol).

D) 1- [D-3- (acetylthio) -2-methyl-1-oxoproyl] -4,4-difluoro-L-Eroline To a stirred solution of 2.7 g of 4,4-difluoro-L-proline hydrochloride bromide in 30 ml of water, cooled to 50, solid carbonate was added to adjust the pH to 8.4. Then, with continuous cooling and stirring, 2.4 g of D-3-ethylthio-2-methylpropionyl chloride in 3 ml of anhydrous ether were added dropwise, while maintaining the pH of the solution at 8.1-8.3 by adding a 25% aqueous sodium carbonate solution. Stirring and cooling are continued for one hour after the addition is complete. The reaction mixture is extracted with ethyl acetate (2 x 25 ml) and the extracts are discarded. To the aqueous layer is added 50 ml of ethyl acetate, while stirring and cooling, concentrated hydrochloric acid is added dropwise to a pH of 2.0. The aqueous layer is saturated with sodium chloride and the ethyl acetate layer is separated. The aqueous layer is extracted with ethyl acetate (3 x 25 ml) and the combined ethyl acetate extracts are dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired product. The dicyclohexylamine salt is prepared by dissolving the product in 40 ml of ethyl acetate and adding a solution of 2.3 g of dicyclohexylamine in 5 ml of ethyl acetate. The precipitated salt is filtered and recrystallized from ethanol. The dicyclohexylamine salt of 1- [D-3- (acetylthio) -2-methyl-oxopropyl] -4,4-difluoro-L-proline melts at 225-2270; 7901519-3 was 25 D = -70 ° (c = 0.5% in methanol).

[Q] -The free acid is recovered by dissolving the dicyclohexylamine salt in 5% aqueous potassium sulfate and extracting with ethyl acetate. The ethyl acetate solution is dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired 1- [D-3- (acetylthio) -2-methyl-1-oxopropyl] -4,4-difluoro-L-proline.

Example 1-4,4-Difluoro-1- (D-3-mercapto-2-methyl-1-oxonronyl) -L-nrolin Argon is passed through a cooled solution of 4.6 ml of concentrated ammonium hydroxide in 11 ml of water. To this solution is added, with stirring in an argon atmosphere, 2.1 g of 1- [D-3- (acetylthio) -2-methyl-1-oxoprooyl] -4,4-difluoro-L-proline. The reaction mixture is stirred for a further two hours and then extracted with ethyl acetate, which is discarded. The aqueous layer is stirred, 30 ml of ethyl acetate are added and the aqueous layer is acidified with concentrated hydrochloric acid. The aqueous layer is saturated with sodium chloride and the ethyl acetate layer is separated. The aqueous layer is extracted with ethyl acetate (3 X 25 ml). The combined ethyl acetate extracts are dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give the desired 4,4-difluoro-1- (D-3-mercapto-2-methyl-1-oxopropyl) -L-proline as a syrup; optical rotation j fl jšö -§5 ° (c = 1; methanol).

Example gel 16 cis-4-chloro-1- (3-acetylthio-2-D-methyl-propanoyl) -L-proline Cis-4-chloro-L-proline, hydrobromide (3.5 g) and D-3-acetylthio Methyl propionyl chloride (2.8 g) was reacted in 40 ml of water containing 2.3 g of sodium carbonate (the acid chloride was first dissolved in 4 ml of ether). The reaction mixture was maintained at pH 8.2-8.4 by adding 8 ml of 25% sodium carbonate solution for 10 minutes. The reaction mixture was stirred for an additional hour and the product was extracted with ethyl acetate to give 3.6 g of a viscous oil which formed a dicyclohexylamine salt in ethyl acetate, m.p. 189-1920 (sintering at 185 DEG C.), which was recrystallized from isopropanol, m.p. -192 ° C (sintering at 1880). 7991510-3 I? Example 17 Cis-4-chloro-1- (3-mercapto-2D-methylpropanoyl} -L-proline The product from Example 16 (1.6 g) was hydrolyzed in 9 ml of H 2 O containing 4 ml of concentrated ammonium hydroxide to give 1.2 g product which, after trituration with hexane, gave 1.1 g of a colorless solid, mp 138-1400; [&] š6-790 (c = 1, ethanol).

Claims (11)

Compounds of the general formula (I) RR '2 \\\ C //' 2 R4 R3 HZC CH2 n _______ ¿_ Rs- (cu m lm cH-co - N * HC ° R 1 wherein R is hydrogen, lower alkanoyl or p-methoxybenzyl; n is 0 or 1; R 1 is hydrogen or lower alkyl; R 2 and R 12 are each hydrogen or halogen; R 3 is hydrogen, lower alkyl or CF 3 and may also be halogen when n is 1; R 4 is hydrogen, lower alkyl or trifluoromethyl; at least one of R 2, R '2, R 3 and R 4 is halogen or CF 3 as represented by the symbols and only R 2 and R' 2 may both be halogen at the same time, and basic salts thereof. A compound according to claim 1 having the formula 122 R 12 R 1; R 1 wherein R is hydrogen, lower alkanoyl or p-methoxybenzyl, R 1 is hydrogen or lower alkyl; R 2, R '2 and R 6 are each hydrogen or halogen; R 3 is hydrogen, lower alkyl, halogen or trifluoromethyl; R 4 is hydrogen, lower alkyl or trifluoromethyl; and n is 0 or 1; with the exception that at least one of R 2, R 3, R 4 and R 5 is a halogen substituent represented by the symbol, only R 2 7901510 And R '2 can both be halogen and when R 3 is halogen n must be 1; and basic salts thereof. A compound according to claim 1 having the formula R 2 R 5 R 4 T 3 R - s - (LH) -C- 'CO * N C °° R 1 wherein R is hydrogen, lower alkanoyl or pemethoxybenzyl, R 1 is hydrogen or lower alkyl; R 2 and R 5 are each hydrogen or fluorine; R 3 and R 4 are each hydrogen or trifluoromethyl, one being hydrogen and the other being trifluoromethyl; and n is 0 or 1; and basic salts thereof. A compound according to claim 1 having the formula R R 2 R 4 R 5 I R s- (cHyIT-cn-co-N cooR 1 wherein R and R 1 have the meaning given in claim 2; R 2 and R 5 are each hydrogen or fluorine; R 3 is hydrogen, halogen or lower alkyl; R 3 is halogen when both R 2 and R 5 are hydrogen and R 3 is other than halogen when R 2 and R 5 are halogen; R 4 is hydrogen; and n is 0 or 1; and basic salts thereof. A compound according to claim 1 having the formula RR '2 2 \ / / C \ HC CH 114 1 | 23 2' 2 R * s-'ïcrnn c fl-co- N cH-cooR 7901516-3 'd wherein R is hydrogen , lower alkanoyl or p-methoxybenzyl; n is 0 or 1; R 1 is hydrogen or lower alkyl; R 2 and R 12 are each hydrogen or halogen; R 3 and R 4 are each hydrogen, lower alkyl or trifluoromethyl, not more than one being trifluoromethyl, and at least one of R 2, R '2, R 3 or R 4 is a halogen substituent represented by the symbol; and basic salts thereof. A process for the preparation of compounds of the general formula m 2 \ C / 1: 4 1: 3 Hzrl: N R- S-- (CEÜ-ñr-CH-CO-- wherein R is hydrogen, lower alkanoyl or pemethoxybenzyl; n is 0 or 1; R 1 is hydrogen or lower alkyl; R 2 and R 12 are each hydrogen or halogen; R 3 is hydrogen, lower alkyl or CF 3 and may also be halogen when n is 1; R 4 is hydrogen, lower alkyl or trifluoromethyl, at least one of R 2, R 2, R 3, R 4 and R 6 is halogen or CF 3 may both be halogen simultaneously, and basic salts thereof, characterized in that the acid is coupled to the formula as represented by the symbols and only R2 and R'2 (IIY R R3 CH --- ~ COOH to the amino acid of the formula 7901510 ~ 3 33 (III) 'Rz R 2 \ C »/ z cr: Hzï I 2 HN CH COORI wherein R is lower alkanoyl or p-methoxybenzyl, and optionally hydrolyzes the product to a product wherein R is hydrogen. 7. A process according to claim 6, characterized in that R is hydrogen or lower alkanoyl; R 1 is hydrogen or lower alkyl; R 2 and R 12 are hydrogen or halogen; R 3 is hydrogen or * lower alkyl; R 4 is hydrogen or lower alkyl. 8. A process according to claim 6, characterized in that R is hydrogen or lower alkanoyl; R 1 is hydrogen or lower alkyl; R 2 and R 12 are each hydrogen or fluorine; R 3 is hydrogen or lower alkyl and R 4 is hydrogen or lower alkyl. 9. A process according to claim 6, characterized in that R is hydrogen and R 2 and R '2 are each fluorine. 10. A process according to claim 6, characterized in that R, R 2, R 12 and R 4 are all hydrogen and R 3 is trifluoromethyl. in ll. A process according to claim 6, characterized in that R and R1 are hydrogen; R 2 is hydrogen or fluorine; R '2 is fluorine; R 3 is methyl; R4 is hydrogen and n is l. 7901510-3 SUMMARY Compounds of the general formula (I) R 2 * \\ R4 R3 Rs-4ca) E-cH-co-- /// FIZ C \\\\\\ CH2 c [IN cm-cooal 'k H2 wherein R is hydrogen, lower alkanoyl or p-methoxybenzyl; n is 0 or 1; R 1 is hydrogen or lower alkyl; R 2 and R 12 are each hydrogen or halogen; R 3 is hydrogen, lower alkyl or CF 3 and may also be halogen when n is 1; R 4 is hydrogen, lower alkyl or trifluoromethyl; at least one of R 2, R '2, R 3 and R 4 is halogen or CF 3 as represented by the symbols and only R 2 and R' 2 may both be halogen simultaneously, and basic salts thereof. The compounds are useful as hypotensive agents.