IE49790B1 - Derivatives of mercaptoacyl amino acids - Google Patents

Abstract

and alkyl esters and salts thereof, wherein R1 is hydrogen, alkanoyl or benzoyl, R2 is hydrogen, alkyl or trifluoromethyl, n is 0 or 1 and A1 and A2 each is an alpha -amino or alpha -imino acid residue, have hypotensive activity and can be incorporated into pharmaceutical compositions.

Description

This invention provides compounds having the formula I Rj-A-pS- (CH2) n-CH-C-A2 and alkyl esters and salts thereof. Such compounds are inhibitors of the action of angiotensin-converting enzyme, and can be used to treat hypertension. In formula I, and throughout the specification, the symbols are as defined below.

R^ is hydrogen, alkanoyl, or benzoyl; R2 is hydrogen, alkyl or trifluoromethyl; n Is 0 or 1; and A-^ and A2 each is an a-amino or a-imino acid residue. The A^ residue is linked to the R^ group through the α-amino or α-imino group and linked to the sulfur atom through the carboxyl group.

The A2 residue is joined to the adjacent carbonyl group through its α-amino or α-imino group.

The two compounds N-(3-(benzoyl-phenylalanylthio) 2-D-methylpropanoyl)-L-proline and N-(2-benzoylphenylalanylthiopropanoyl)-L-3,4-dehydroproline are however excluded from the monopoly claimed in this application.

The term alkyl, as used throughout the specification, refers to groups having 1 to 7 carbon atoms. 49780 The term alkanoyl, as used throughout the specification, refers to alkanoyl groups having 2 to 7 carbon atoms. Acetyl is the preferred alkanoyl group.

The α-amino and α-imino acid residues represented by A^ and A^ can be either naturally occurring or synthetic. Exemplary groups are proline, 4-hydroxyproline, 4-chloroproline, 4-fluoroproline, 4,4-difluoroproline, 4,4-ethylenedioxyproline, 4-methoxyproline, 4-thiazolidinecarboxylic acid, tryptophane, glycine, alanine, leucine, isoleucine, valine and phenylalanine residues.

II R'4 R.-A.,-S-(CH-) -CH-C-N· 11 2 n II P.-OH, and alkyl esters and salts thereof. In fonnula II, and throughout the specification, R^ is hydrogen or fluoro and R^ is hydrogen, hydroxy, methoxy, chloro, or fluoro, or together with the carbon atom to which they are attached R^ and R4 form an ethylenedioxy group.

Those compounds of formula I wherein the α-amino or α-imino residues of and A2 are in the L-configuration are also preferred.

The products of this invention can be prepared by first reacting an α-amino or a-imino acid (with protected nitrogen atom) having the formula R5-Ai with a mercaptoacyl amino acid having the formula III 49780 IV or an alkyl ester thereof. The particular R5 nitrogen protecting group used is not critical; exemplary of the known protecting groups are t-butyloxycarbonyl, benzyloxycarbonyl, and onitrophenylsulfenyl. Any other nitrogen protecting group that can later be removed under mild conditions can also be used, provided that it protects against racemization of A^ during the activation step described below. The R5 group can of course also be alkanoyl or benzyol as defined in Rj, although these groups are not considered protecting groups in the sense that they are not as easily removable as the above-mentioned protecting groups and may not afford protection against racemization.

The novel reaction yields a novel cctipound having the formula or alkyl ester thereof, and is carried out by first activating the carboxyl group of a compound of formula III, using art-recognized procedures. For example, activation can be accomplished by reaction of a compound of formula III with Ν,Ν'-carbonyl-bis-imidazole or with a mixture of base and alkylchloroformates. The reaction of a compound of formula III (with activated carboxyl group) can be accomplished in an organic 'is solvent, e.g., a halogenated hydrocarbon, preferably in the presence of an organic base.

Reaction conditions are not critical, and the reaction can conveniently be carried out at room temperature.

The blocking group Rj can be removed from a compound of formula V, using art-recognized procedures, to yield the corresponding product of formula I wherein Rj is hydrogen.

Those products of fonnula I wherein R^ is alkanoyl or benzoyl caN also be prepared from a product wherein R-^ is hydrogen by reaction with the appropriate alkanoic acid anhydride or benzoyl halide respectively.

The starting materials of formula IV, and methods for their preparation, are described in the literature; see, for example, United States patents 4,046,889, 4,105,776 and 4,053,651.

As described therein an α-amino or α-imino acid (A2) can be coupled with a haloalkanoic acid of the formula VI R, I2 X-(CH,) -CH-C-OH 2 n fi wherein X is a halogen, preferably chlorine or bromine, by one of the known procedures in which the acid VI is activated, prior to reaction with the acid Ag, involving formation of a mixed anhydride, symmetrical anhydride, acid chloride, active ester or use of Woodward reagent K, EEDQ (N-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline) or the like. The product of this reaction is a 40790 compound of formula X-(CH,, -CH-C-A, . n || 2 Subjecting a compound of formula VII to a displacement reaction with the anion of a thioacid of the formula VIII II Rg-C-SH , wherein Rg is alkyl, aryl or arylalkyl, yields a compound having the formula IX R I :,-C-S- (CH,) -CH-C-A, ο ί η μ i which can then be converted to the mercapto conpound of formula IV by ammonolysis. The art also discloses several alternative processes for preparing the compounds of formula IV.

The conpounds of this invention form basic salts with various organic and inorganic bases which are also within the scope of this invention. Such salts include ammonium salts, alkali metal salts like sodium and potassium salts (which are preferred,, alkaline earth metal salts like the calcium and magnesium salts, salts with organic bases e.g., dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, hydrabamine salts, and salts with amino acids like arginine, lysine and the like. The nontoxic, physiologically acceptable salts are preferred, although other salts are also useful, e.g., in isolating or purifying the product.

The compounds of formula X, and the alkyl esters and salts thereof, may ce used as hypotensive agents. They inhibit the conversion of the decapeptide angiotensin I to angiotensin II and, therefore, may be used in reducing or relieving angiotensin related hypertension. The action of the enzyme renin on angiotensinogen, a pseudoglobulin in blood plasma, produces angiotensin I. Angiotensin I is converted by angiotensin converting enzyme (ACE) to angiotensin II. The latter is an active pressor substance which has been implicated as the causative agent in various forms of hypertension in various mammalian species, e.g., rats and dogs. The compounds of this invention intervene in the angiotensinogen-·· (renin, + angiotensin I-»-(ACE)-*angiotensin II sequence by inhibiting angiotensin converting enzyme and reducing or eliminating the formation of the pressor substance angiotensin II. Thus by the administration of a composition containing one or a combination of compounds of formula I, angiotensin dependent hypertension in the species of mammal suffering therefrom is alleviated.

A single dose, or preferably two to four divided daily doses, provided on a basis of about 0.1 to 100 mg. per kilogram of body weight per day, preferably about 1 to 50 mg. per kilogram of body weight per day is appropriate to reduce blood pressure. The substance is preferably administered orally, but parenteral routes such as the subcutaneous, intramuscular, intravenous or intraperitoneal routes can also be employed.

The carpounds of formula I can be formulated with a pharmaceutical carrier for use in tte reduction of blood pressure in compositions such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral administration.

About 10 to 500 mg. of a compound or mixture of compounds of formula I may be ccnpounded with a physiologically acceptable vehicle, carrier, excipient, binder, preservative, stabilizer, flavor, etc., in a unit dosage form as called for by accepted pharmaceutical practice. The amount of active substance in these compositions or preparations is such that a suitable dosage in the range indicated is obtained.

Depending on the nature of the R substituents, the products of formula I may have one or more asymmetric carbons and, therefore, exist in stereoisomeric forms or in racemic mixtures thereof. All of these are within the scope of this invention. In the above described syntheses, one of the enantiomers or the racemate can be used as the starting material. When the racemic starting material is used, the stereoisomers obtained in the product can be separated by conventional techniques; e.g., chranatography or fractional crystallization.

The following examples are specific embodiments of this invention. 0 - 10 Example 1 (S)—1—[3—[(1-Acetyl-L-prolyl)thio]-2-methyl-loxopropyl} -L-proline A) (S)-1-[3-[ (1-(t-Butyloxycarbonyl)-L-prolyl] thio]-2-methyl-l-oxopropyl]-L-proline (t-Butyloxycarbonyl)-L-proline (1.290g) is taken into 10 ml. of dichloromethane with stirring in an ice bath; Ν,Ν'-carbonyl-bisimidazole (972mg) is added. After 1 hour, (S)— 1-(3-mercapto-2-methyl-l-oxopropyl)-L-proline (1.085g) in 5 ml. of dichloromethane and 0.7 ml. of triethylamine is added. After an additional hour, the ice bath is removed and the reaction is allowed to proceed for about 16 hours at room temperature. The dichloromethane is removed in vacuo and the residue is taken into ethyl acetate and washed with 10% potassium sulfate, yielding 2.4 g of material. This material is purified on a silica gel column which is eluted with ethyl acetate: buffer (200:37; buffer is pyridine: acetic acid: water, 20:6:11). The pooled fractions are taken into ethyl acetate and washed with 10% potassium sulfate yielding 1.8 g of the title compound. - 11 B) (S)—1—[3—[(1-Acetyl-L-prolyl)thio]-2-methyl-loxopropyl] -L-proline (S)-1-(3-[[1-(t-Butyloxycarbonyl)-L-prolyl] thio]-2-methyl-l-oxopropyl]-L-proline (1.8g) is treated for 15 minutes at room temperature in 5 ml. of trifluoroacetic acid and 5 ml. of anisole. The reaction mixture is concentrated in vacuo and treated twice with ether:hexane. The residue is dried over potassium hydroxide in vacuo, and acetylated in 10 ml. of anhydrous pyridine using 0.41 ml. of acetic anhydride for 2 hours.

The reaction mixture is concentrated in vacuo, water is removed twice, and the residue is lyophilized. Purification on sulfonated polystyrene cation exchange resin using water as eluant, followed by crystallization from ethyl acetate: ether yields 700 mg. of the title compound, melting point 81-83°C.

Example 2 (5)-1-(2-1 (1-Acetyl-L-prolyl) thio)-1-oxopropyl] L-proline A) (S)-1-[2—[[1-(t-Butyloxycarbonyl)-L-prolyl] thio]-1-oxopropyl]-L-proline (t-Butyloxycarbonyl)-L-proline (1.075g) is taken into 10 ml. of dichloromethane and chilled with stirring in an ice bath; N,N'carbonyl-bis-imidazole (810 mg.) is added. - 12 After 1 hour, S-l-(2-mercapto-2-methyl-1-oxopropyl)L-proline (1.015g) in 5 ml. of dichloromethane and 0.7 ml. of triethylamine is added. After an additional hour, the ice bath is removed and the reaction is allowed to proceed for about 16 hours at room temperature. The mixture is concentrated in vacuo, taken into ethyl acetate and washed with 10% potassium sulfate, yielding 2.0 g of material. The material is purified on a silica gel column which is eluted with ethyl acetate: pyridine: acetic acid: water (120:20:6:11) and crystallized from ethyl acetate: hexane (1:2) yielding 1.076 g, melting point 143-144°C.

B) (S)-l-[2—[(1-Acetyl-L-prolyl)thio]-1-oxopropyl]L-proline (S)-1-12— ([1- (t-Butyloxycarbonyl)-Lprolyl)thio]-1-oxopropyl]L-proline (1.076g) is treated for 15 minutes at room temperature with 5 ml. of trifluoroacetic acid and 2 ml. of anisole. The reaction mixture is concentrated in vacuo and treated twice with ether: hexane. The residue is dried over potassium hydroxide in vacuo and acetylated for 2.5 hours in 5 ml. of anhydrous pyridine with 0.23 ml. of acetic anhydride. The reaction mixture is concentrated to dryness in vacuo and lyophilized from water. Purification on sulfonated polystyrene cation exchange resin followed by lyophilization yields 700 mg. of the title compound. 4-9 79 0 - 13 Example 3 (S)-1-[2-1(N-Acetyl-L-phenylalanyl)thio]-1-oxopropyl]L-proline A) (S)—1—12—[[N-(t-Butyloxycarbonyl)-L-phenylalanyl] thio]-1-oxopropyl]-L-proline (t-Butyloxycarbonyl)-L-phenylalanine(1.325g) is taken into 10 ml. of dichloromethane and chilled with stirring in an ice bath; N,N'-carbonylbis-imidazole (810mgJ is added. After 1 hour, (S)-l-(2-mercapto-l-oxopropyl)-L-proline (1.015g) in 5 ml. of dichloromethane and 0.7 ml. of triethlamine is added. After an additional hour the ice bath is removed and the reaction is allowed to proceed for about 16 hours at room temperature.

The mixture is concentrated in vacuo, taken into ethyl acetate and washed with 10% potassium sulfate, yielding 2.3 g of material. The material is purified on a silica gel column which is eluted with ethyl acetate: buffer (120:37; buffer is pyridine: acetic acid: water, 20:6:11) and crystallized from ether: hexane to yield 1.553 g of the title compound, melting point 59-62°C.

B) (s)-1-[2-[ (N-Acetyl-L-phenylalanyl)thio]-1-oxopropyll-L-proline (SJ-1— 12— [ [N- (t-Butyloxycarbonyl)-L-phenylalanyl] thio)-1-oxopropyl]-L-proline (1.553g) is treated for 15 minutes at room temperature with 6 ml. of - 14 trifluoroacetic acid and 3 ml. of anisole. The reaction mixture is concentrated in vacuo and the residue is triturated with ether to yield 1.1 g of material. This material is acetylated for 2 hours at room temperature in 6 ml. of anhydrous pyridine with 0.28 ml. of acetic anhydride, concentrated in vacuo, taken into ethyl acetate and washed with 10% potassium sulfate. The organic layer is dried and taken to dryness in vacuo. The residue is crystallized from ethyl acetate, yielding 600 mg. of the title conpound, melting point 191-192°C. -.15 Example 4 (S)-1-(3-((1-Benzoyl-L-prolyl)thio]-2-methyl-1oxopropyl)-L-proline By substituting benzoyl chloride for the acetic anhydride in the procedure of Example 1, the title compound is obtained.

Example 5 (S)-1-(3-((l-Acetyl-L-tryptophyl)thio)-2-methyl-loxopropyl]-L-proline By substituting t-butyloxycarbonyl-L-tryptophan for the t-butyloxycarbonyl-L-proline in the procedure of Example 1, the title compound is obtained.

Example 6 (S)-1-(3-((1-Acetyl-L-isoleucyl)thio]-2-methyl-loxopropyl ]-L-proline By substituting t-butyloxycarbonyl-L-isoleucine for the t-butyloxycarbonyl-L-proline in the procedure of Example 1, the title compound is obtained.

- IS Example 7 (S)—1—[3—I(l-Acetyl-L-phenylalanyl)thio]-2-methyl1- oxopropyl)-L-4,4-ethylenedioxyproline 5 By substituting t-butyloxyearbonyl-L-phenylalanine for t-butyloxyearbonyl-L-proline and S-l(3-mercapto-2-methyl-l-oxopropyl)-L-4,4-ethylenedioxyproline for the S-l-(3-mercapto-2-methyl-l10 oxopropyl)-L-proline in the procedure of Example 1, the title compound is obtained.

Examples 8-28 Following the procedure of Example 1, but substituting the amino acid derivative listed in column I for t-butyloxycarbonyl-L-proline and the compound listed in column II for (S)-1-(3-mercapto2- methyl-l-oxopropyl,-L-proline, yields the compound listed in column III.

As used below the symbol Boc refers to tbutyloxycarbonyl and the symbol Ac refers to acetyl. The other symbols are standard nomenclature. ί - 17 Example Column I Column II Column III >1 f-1 ? υ co x cj O υ X CJ o u ffi OJ o y <*) ffi ffi O y I o n U X X u-u CJ X u I to X o Γ7 u ffi ffi u-u OJ ffi u I ω ffi I o OJ ffi U I w ffi I O ro o ffi ffi O-U I Oi ffi V w ffi rH <0 u ffi σ> ffi I υ r—i < I ffi A $ I υ o n οι rd tc Ol o u X Ol o o X Ol o υ Example Column I Column II Column ΙΙΓ X X '<1 =<1 *r — * ι ι -z I o m u X CC 0-0 OJ X u I tn I Cb u I ϋ I O n O X X 0-0 oj X o I tn I Φ r—( H I U rtJ Z I o n o x a 0-0 oi X o I tn I GJ Λ Cb % -d X N O o X oi o o a Ol O O X Ol O O z I o u fn l X X 0-0 I OJ X o I tn X Cb υ o ra I o ω o X X ο—o oi X o I tn ι Φ X Cb I ϋ w o n u X X 0-0 tn ι >1 o o c ο o c X X X X oi O O x Ol O O -z I o n o X X 0-0 OJ X u J tn x < o n O X X o—u OJ X o I cn x z I o n o X X o-o oi X u I cn x “Cl '—z I o cnO X X o-o I cn a H t ϋ ra Q) φ >1 43 43 H Cb I Cb | ϋ | 1 ϋ 1 ϋ U 0 0 0 ra ra ra - 19 Examole Column I Column IT Column III C ι u □ co QJ Gi Gi J3 M G ft • | e< | 1 ϋ o u 0 0 0 CQ CQ CQ CS CS • 49790 - 20 Example Column 1 Column II Column Eli a a a CM CM c o O o U u u a CM O U <1 =<1 Cl -<1 1» a CM O U O m u CC cc u-u I ω ι ω 4C & I ϋ rf O n U X X u-u I co I r-l <0 > I o <*ϊ u a u-u I ω ι φ rd H I £ O co U a a u-u l co I u rf z I o rn U a a u-u ι co I Φ X3 & I o rf a CM o u CM O U <1 = a v- a I o m U a a u-u I ω a a CM O u a CM o 2 z fe z | ( o o I o co U m u n □ u a S K a a J-U u-u I U“U 1 ω ω co a a a 0) 4C &4 I a (0 υ o a ι o a s I a to CM Q) Λ a I ϋ o a > CM - 21 Example Column I Column II Column III ι o r> u a a υ-υ , ω a α M H I υ o a (M - 22 Example 29 (S)-1-[2-f(H-Acetyl-L-tryptophyl)thio]-1-oxopropyl]L-proline By substituting t-butyloxyearbonyl-L-tryptophan or the t-butyloxycarbonyl-L-phenylalanine in the procedure of Example 3, the title compound is obtained.

Claims (21)

1. A compound having the fonnula * 2 R.-A,-S-(CH,) -CH-C-A, ii i η μ i cr such a conpound in alkyl ester or salt form, wherein R^ 5 is hydrogen, alkanoyl or benzoyl; Rg is hydrogen alkyl or trifluoromethyl; n is 0 or 1; and A^ and Ag each is an α-amino or α-imino acid residue/ wherein the A^ residue is linked to the R 1 group through the α-amino or α-imino group and 10 linked to the sulfur atom through the carboxyl group, and wherein the Ag residue is linked to the adjacent carbonyl group through its α-amino or α-imino group, with the proviso that said compound is not N-(-3-(benzoylphenylalanylthio)-2-D-methylpropanoyl)-L-proline or 15 ι N-(2-benzoylphenylalanylthiopropanloyl)-L-3,4,dehydroproline.

' 2. A compound in accordance with claim 1, wherein is hydrogen.

3. A compound in accordance with claim 1 wherein 20 r^ is alkanoyl.

4. A compound in accordance with claim 1, wherein R^ is benzoyl.

5. A compound in accordance with claim 1 wherein Rg is hydrogen. 25

6. A compound in accordance with any one of claims 1 to 4, wherein Rg is alkyl. - 24

7. A compound in accordance with any one of claims 1 to 4, wherein Sj is trifluoromethyl.

8. A compound in accordance with any preceding claim wherein n is 0. 5

9. A compound in accordance with any one of claims 1 to 7, wherein n is 1.

10. A compound in accordance with aiy preceding claim, wherein A^ and each is 4-fluoroproline, 4,4difluoroproline, 4,4-ethylenedioxyproline, 4-methoxy10 proline, 4-thiazolidinecarboxylic acid, tryptophane, glycine, alanine, leucine, isoleucine«valine or phenylalanine - residue.

11. A compound in accordance with claim 10, wherein the α-amino or α-imino residues of A^ and 15 A 2 are in the L—configuration.

12. A compound in accordance with claim 1 having the formula or an alkyl ester of salt thereof, wherein is hydrogen, alkanoyl or benzoyl; R 2 is hydrogen alkyl or trifluoromethyl; n is 0 or 1; R 3 is hydrogen or fluoro and R 4 is hydrogen, hycroxy, methoxy, chloro or 25 fluoro or together with the carbon atom to which - 25 they are attached, Rj and R^ form an ethylenedioxy group.

13. The compound in accordance with claim 1, (S)-1-[3-[(1-acetyl-L-prolyl)thio]-2-methyl-loxopropy1]-L-proline.

14. The compound in accordance with claim 1, (S)-1-[2-[(1-acetyl-L-prolyl)thio)-1-oxopropyl)L-proline.

15. The compound in accordance with claim 1, (S)-1-[2-[ (N-aoetyl-L-phenylalanyl)thio)-1-oxopropylL-proline.

16. A compound of the formula Γ 2 Rg-A^S-iCH^H-CH-C^ Wherein A^, A 2 , Rj and n axe as defined in claim 1 and Rj is a nitrogen atom protecting group.

17. A compound in accordance with Claim 1 or 16 as named or shown in any of the Examples.

18. A pharmaceutical composition comprising a compound according to any one of claims 1 to 15 or 17 (as appendant to claim 1) and a pharmaceutical carrier.

19. A composition in accordance with Claim 18, in the form of a tablet, capsule or elixir for oral administration or a sterile solution or suspension for parenteral administration.

20. A composition in accordance with Claim 18 or 19 which includes an excipient, binder, preservative, stabiliser or flavor.

21. A compound in accordance with any of claims 1 to 15 or 17 (as appendant to claim 1) for use in the treatment of hypertension.