EP0513016A1 - Cycloalkyl-substituted glutaramide diuretic agents - Google Patents

Abstract

The invention relates to compounds represented by the formula: (I); where: A completes a closed carbocyclic chain with 4-7 elements, which can be saturated or mono-unsaturated and which can optionally be fused with another closed carbocyclic chain with 5 or 6 elements saturated or unsaturated; R represents H, C1-C6 alkyl, benzyl or an alternative biolabile ester group; R1 represents H or C1-C4 alkyl; R2 represents H, OH, C1-C4 alkyl, C1-C4 alkoxy, halo or CF3; R3 represents CH2 OH or CO2R4, where R4 is identical to R defined above; and R5 is defined as being able to comprise a range of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl and substituted alkyl groups containing in particular a methoxyethyl, an S-lysylaminomethyl, an N2-acetyl-S-lysylaminomethyl and an N2-methanesulphonyl-S- lysylaminomethyl. These compounds are atriopeptidase inhibitors, useful in the treatment of hypertension, heart failure, kidney failure and other disorders.

Description

"Cycloalkyl-substituted glutaramide diuretic agents

This invention relates to a series of cycloalkyl-substituted glutaramide derivatives which are diuretic agents having utility in a variety of therapeutic areas including the treatment of various cardiovascul ar disorders such as hypertension, heart failure and renal insuffici ency.

According to the specification of our European patent applications EP-A-0274234 and EP-A-0343911 we describe and claim certain cycloalkyl-substituted glutaramide derivatives as diuretic agents. The present invention provides further related compounds having a 2,3-d-hydroindene substituent.

The cxxnpcunds are inhibitors of the zinc- dependent, neutral endopeptidase E.C.3.4.24.11. This enzyme is involved in the breakdown of several peptide hormones, including atrial

natriuretic factor (ANF), which is secreted by the heart and which has potent vasodilatory, diuretic and natriuretic activity. Thus, the compoun ds of the invention, by inhibiti ng the neutral endopeptidase E.C.3.4.24.11, can potentiate the biological effects of ANF, and in particular the conpcunds are diuretic agents having utility in the treatment of a number of disorders, including hypertension, heart failure, angina, renal insufficiency, premenstrual syndrome, cyclical oedema, Menieres disease, hyperaldosteronism (primary and secondary) pulmonary oedema, ascites, and hypercalciuria. In addition, because of their ability to potentiate the effects of ANF the compounds have utility in the treatment of glaucoma. As a further result of their ability to inhibit the neutral endopeptidase E.C.3.4.24.11 the compounds of the invention may have activity in other therapeutic areas ircluding for example the treatment of asthma, innflammation, pain, epilepsy, affective disorders, dementia and geriatric confusion, obesity and gastrointestinal disorders

(especially diarrhoea and irritable bowel syndrome), the

modulation of gastric acid secretion and the treatment of hyperreninaemia and leukaemia.

The compounds of the present invention are of the formula:

(I) wherein A completes a 4 to 7 membered carbocyclic ring which may be saturated or mono-unsatu rated and which may optionally be fused to a further saturated or unsaturated 5 or 6 membered carbocyclic ring ;

R is H, C₁-C₆ alkyl, benzyl or an alternative biolabile ester-forming group;

R¹ is H or C₁-C₄ alkyl;

R² is H, OH, C₁-C₄ alkyl, C₁-C₄ alkoxy, halo or CF₃; R³ is CH₂OH or CO ₂R ⁴ wherein R ⁴ is as previously defined for R;

and R ⁵ is C₁-C₆ alkyl, C₂-C₆ alkenyl, C₂-C₈ alkynyl,

C₃-C₇ cycloalkyl, or C₃-C₇ cycloalkenyl,

or R ⁵ is C₁-C₆ alkyl substituted by halo, hydroxy, C₁-C₆.

alkoxy, C₁-C₆ alkoxy (C₁-C₆)alkoxy, C₃-C₇ cycloalkyl, C₃-C₇ cycloalkerryl, aryl, aryloxy, heterocyclyl, -NR⁶R⁷,

-NR⁸COR⁹, -NR⁸SO₂R¹⁰, -CONR⁶R⁷ or R⁶R⁷N-(C₁-C₆)alkoxy; or R ⁵ is C₁-C₆ alkyl substituted by a group of the formula:

2

R¹⁴

ON R¹⁵

wherein R⁶ and R⁷ are each inde pendently H, C₁-C₄ alkyl, C₃-C₇ cycloalkyl, aryl, aryl (C₁-C₄)alkyl, C₂-C₆ alkoxyal kyl, or heterocyclyl; or the two groups R⁶ and R⁷ are taken together with the nitrogen to which they are attached to form a pyrrolidirfyl, piperidino, morpholino, piperazinyl or N-(C₁-C₄)alkyl-piperazinyl group;

R⁸ is H or C₁-C₄ alkyl;

R⁸ is C₁-C₄ alkyl, CF₃, aryl, aryl(C₁-C₄)alkyl, aryl(C₁-C₄)alkoxy, heterocyclyl, C₁-C₄ alkoxy or NR⁶ R ⁷ wherein R⁶ and R⁷ are as previously defined;

R¹⁰ is C₁-C₄ alkyl, C₃-C₇ cycloalkyl, aryl or heterocyclyl;

R¹¹ is H, C₁-C₆ alkyl, aryl or C₃-C₇ cycloalkyl;

R¹² is R¹¹CONR¹¹-, R¹¹SO₂NR¹¹-, R¹⁶R¹⁷N- (CH₂ )_p-, or

R¹¹O-, wherein each R¹¹ is as previously defined above;

R¹³ and R¹⁴ are each independently H or C₁-C₆ alkyl; or

R¹³ is H and R¹⁴ is C₁-C₆ alkyl which is substituted by

OH, C₁-C₄ alkoxy, SH, SCH₃, NH₂, aryl(C₁-C₆)alkyl-

OCONH-, NH₂CO- , CO₂H, guanidino, aryl, or heterocyclyl; or the two groups R¹³ and R¹⁴ are joined together to form, with the carbon atom to which they are attached, a

5 or 6 member ed carbocylic ring which may be saturated or mono-unsaturated and which may optionally be substituted by C₁-C₄ alkyl or fused to a further 5 or 6 membered saturated or unsaturated carbocy clic ring; or R¹³ is H, and R¹² and R¹⁴ are linked to form a

2-(N-CO R¹¹-4-aminopyrrolidinyl) group;

R¹⁵ is R¹⁶R¹⁷NCO-, R¹¹OCO-, R¹¹OCH₂- or heterocyclyl, wherein R¹¹ is as previously defined above;

R¹⁶ and R¹⁷ are each independently H orC₁- C₆ alkyl; and p is 0 or an integer of from 1 to 6;

and pharrmaceutically acceptable salts thereof and bioprecursors therefor.

In the above definition, unless otherwise indicated, alkyl groups having three or more carbon atoms may be straight or branched-chain . The term aryl as used herein means an arotatic hydrocarbon group such as phenyl, naphthyl or biphenyl which may optionally be substituted with one or more OH, CN, CF₃, C₁-C₄ alkyl, C₁-C₄ alkoxy groups or halo atoms. Halo means fluoro, chloro, bromo or iodo.

The term heterocyclyl means a 5 or 6 membered nitrogen, oxygen or sulphur containing heterocyclic group which, unless otherwise stated, may be saturated or unsaturated and which may optionally include a further oxygen or one to three nitrogen atoms in the ring and which may optionally be benzofused or substituted with for example, one or more halo, C₁ -C₄ alkyl, hydroxy, carbamcyl, benzyl, oxo, amino or mono or di-( C₁ -C₄ alkyl)amino or ( C₁ -C₄ alkanoyl)amino groups. Particular examples of heterocycles include pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, imiidazolyl, pyrazolyl, triazolyl, tetrazolyl, furanyl,

tetrahydrofuranyl, tetrahydropyranyl, dioxanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, indolyl, isoindolinyl, quinolyl,

quinoxalinyl, quinazolinyl and benzimidazolyl, each being optionally substituted as previously defined.

The compounds of formula (I) may contain several asymmetric centres and thus they can exist as enantiomers and diastereomers . The invention includes both mixtures and the separated individual isomers .

The pharmaceutically acceptable salts of the compounds of formula (I) containing an acidic centre are those formed with bases which form non-toxic salts. Examples include the alkali metal salts such as the sodium, potassium or calcium salts or salts with amines such as diethylamine. Compounds having a basic centre can also form acid addition salts with pharmaceutically acceptable acids. Examples include the hydrochloride

hydrobromide , sulphate or bisulphate, phosphate or hydrogen phosphate, acetate, citrate, fumarate, gluconate, lactate, maleate, succinate and tartrate salts.

The term bioprecursor in the above definition means a pharmaceu tically acceptable biologically degradable derivative of the compound of formula (I) which, upon administration to an animal or human being, is converted in the body to produce a compound of the formula (I).

A preferred group of compounds of the formula (I) are those wherein A is (CH₂)₄ and R¹ and R² are H, i.e. compounds of the formula (II) below wherein R, R³ and R⁵ are as previously defined for formula (I):

Also preferred are those compounds of formulae (I) and (II) wherein R and R⁴ (when R³ is CO₂R⁴ ) are both H (diacids) as well as biolabile mono and di-ester derivatives thereof wherein one or both of R and R⁴ is a biolabile ester-forming group.

The term biolabile ester-forming group is well understood in the art as meaning a group which provides an ester which can be readily cleaved in the body to liberate the corresponding diacid of formula (I) wherein R and R⁴ are both H. A number of such ester groups are well known, for example in the penicillin area or in the case of the ACE-inhibitor antihypertensive agents.

In the case of the compounds of formulae (I) and (II) such biolabile pro-drug esters are particularly advantageous in providing compounds of the formula (I) suitable for oral

administration. The suitability of any particular ester-forming group can be assessed by conventional animal or in vitro enzyme hydrolysis studies. Thus, desirably for optimum effect, the ester should only be hydrolysed after absorption; accordingly, the ester should be resistant to hydrolysis before absorption by digestive enzymes but should be readily hydrolysed by, for example, liver enzymes. In this way the active diacid is released into the bloodstream following oral absorption.

In addition to lower alkyl esters (particularly ethyl) and benzyl esters, suitable biolabile esters include alkancyloxyalkyl esters, including alkyl, cycloalkyl and aryl substituted

derivatives thereof, aryloxyalkyl esters, aroyloxyyalkyl esters, arylalkyloxyalkyl esters, arylesters, aralkylesters, and haloalkyl esters wherein said alkancyl groups have from 2 to 8 carbon atoms and said alkyl groups have from 1 to 8 carbon atoms and are branched or straight chain and said aryl groups are phenyl, naphthyl or indanyl optionally .substituted with one or more C₁-C₄ alkyl or C₁-C₄ alkoxy groups or halo atoms.

Thus examples ofR⁴ and R⁴ when they are biolabile

ester-forming groups other than ethyl and benzyl include:

1-(2,2-diethylbutyryloxy)ethyl, 2-ethylpropionyloxymethyl,

1-(2-ethylpropionyloxy)ethyl, 1-(2,4-dimethylbenzoyloxy)ethyl, 1-(benzcyloxy)benzyl, 1-(benzoyloxy)ethyl, 2-methyl-1- propiorryloxypropyl, 2,4,6-trimethylbenzoyloxymethhyl, 1-(2,4,6- trimethyl-benzyloxy )ethyl, pivaloyloxyrnethyl, phenethyl,

phenpropyl, 2,2,2-trifluoroethyl, 1- or 2-naphthyl, 2,4- dimethylphenyl, 4-t-butyl-phenyl, 5-(4-methyl-1,3-dioxalynyl - 2-onyl)methyl and 5-indarryl.

Compounds of the formulae (I) and (II) wherein R is benzyl or t-butyl and R⁴ is ethyl are valuable irrtermediates for the preparation of the diacids wherein R and R⁴ are both H.

In a further preferred group of compounds R⁵ is methylene substituted by a group of the formula -NHCOCR ¹² R ¹³R^{1 4}, particularly where R¹² is NH₂, R¹¹CONH- or R¹¹SO₂NH-, R¹³ is H andR ¹⁴is -(CH₂)₄NH₂. Particularly preferred are such groups derived from S-lysine; thus especially preferred R ⁵substitutents of this type include S-lysyl-aminomethyl , N²-acetyl-S-lysylaminome thyl andN²-methanesulphonyl-S-lysyl-aminomethyl.

In further groups of preferred Compounds R ⁵is C₁-C₆ alkyl, or C₁-C₆ alkyl substituted by C₁-C₆ alkoxy, particularly

methoxyethyl; or R⁵ is C₁-C₆ alkyl substituted by phenyl.

Particularly preferred individual compounds of the invention include:

2-{1-[2(S)-carboxy-3- (S-lysylamino)propyl]cyclopentyl- carbonylamino} -2,3-dihydroindene-2-carboxylic acid,

2-{1-[2 (S)-carboxy -3-(N²-methanesulphonyl-S-lysylamino)- prppyl]cyclcpentylcarbonylamino} -2,3-dihydroindene-2-carboxylic acid, and 2-{1-[2(S)-carboxy-3-(N²-methanesulphony l-S-lysylamino)- propyl]cyclopentylcarbonylamino}-2-h ydroxymethyl-2,3-dihydroindene and biolabile ester derivatives thereof.

The compounds of formula (I) are prepared by a number of different processes. The basic procedure involves the synthesis of a partially protected cycloalkyl-substi tuted glutaric acid derivative which is coupled to an amine to give the desired glutaramide. The carboxylic acid group in the amine, if free, or any reactive groups in R⁵, may require protection during the coupling step and such protecting groups are removed in the final stages of the process.

The synthetic route is illustrated in Scheme 1 wherein A, R¹ and R ² are as previously defined, R^5' is as defined for R⁵ with any reactive group therein protected if necessary, R ¹⁸ is as defined for R excluding H, or is a conventional carboxylic acid protecting group, and R ^3' is either CH₂OH or CO₂R¹⁹ wherein R¹⁹ is as previously defined forR⁵ excluding H or is a conventional carboxylic acid protecting group:

The reaction of the compounds of formula (III) and (IV) is achieved using conventional amide coupling techniques. Thus in one process the reaction is achieved with the reactants dissolved in an organic solvent, e.g. dichloromethane, using a diimide condensing agent, for example 1-ethyl-3-(dimethylaminopropyl)- carbodiimide, or N,N'-dicyclohexylcarbodiimide, advantageously in the presence of 1-hydroxybenzotriazole and an organic base such as 4-methylmorpholine. The reaction is generally complete after a period of from 12 to 24 hours at room temperature and the product is then isolated by conventional procedures, i.e. by washing with water or filtration to remove the urea by-product and evaporation of the solvent. The product may be further purified by crystallisation or chromatography, if necessary. The compounds of formula (V) include compounds of formula (I) wherein R and R⁴ are

C₁-C₆ alkyl or benzyl.

In some cases the coupled product, in protected form, may be subjected to conventional chemical transformation reactions to allow preparation of further compounds of formula (V). Thus for example compounds of formula (V) wherein R^5' contains an ester group may be hydrolysed or hydrogenated to generate the carboxylic acid which may be further reacted, for example with an amine, to give amide derivatives.

Similarly compounds wherein R^5' contains a substituted or protected amino group (for example a benzylamino, dibenzylamino, benzyloxycarbonylamino or t-butyloxycarbonylamino group) may be converted to the free amines by hydrogenation or protonolysis as appropriate. The amines produced may be further reacted, thus for example reaction with a sulphonyl halide yields the corresponding sulphonamides, acylation with an acid chloride or anhydride yields the corresponding amides, reaction with an isocyanate yields urea derivatives and reaction with a chloroformate yields the carbamate products respectively. All these transformations are entirely conventional and appropriate conditions and reagents for their performance will be well known to those skilled in the art as will other variations and possibilities.

The diesters of formula (V) wherein R^3' is CO₂R¹⁹ may be further reacted to give the monoester of diacid derivatives of formula (I) wherein one or both of R and R⁴ are H. The conditions used will depend on the precise nature of the groups R¹⁸ and R¹⁹ present in the compound of formula (V) and a number of variations are possible. Thus for example when both of R¹⁸ and R¹⁹ are benzyl, hydrogenation of the product will yield the diacid of formula (I) wherein R³ is OX₂R⁴ and R and R⁴ are both H.

Alternatively if one of R¹⁸ and R¹⁹ is benzyl and the other is alkyl, hydrogenation will yield a monoester product. This can be hydrolysed, if desired, again to yield the diacid product. When one of R¹⁸ and R¹⁹ is t-butyl, treatment of the compound of formula (V) with trifluoroacetic acid yields the c orresponding acid. The diester product wherein R¹⁸ and R¹⁹ are benzyl or lower alkyl can also be treated with trimethylsilyl iodide to produce the dicarboxylic acid product. If some other carboxylic acid protecting group is used for R¹⁸ or R¹⁹ then clearly appropriate conditions for its removal must be employed in the final step to give the ester or diacid product of formula (I). In the case where R^3' is CH₂OH a single deprotection step is required to produce the compounds of formula (I) using deprotection methods as appropriate to the particular R¹⁸ group present in the compound of formula (V). In the case where the ring A or the substituent R⁵ is unsaturated, the deprotection must be effected by non-reductive methods, thus for example if either of R and R⁴ is benzyl, they may be removed by treatment with trimethylsilyl iodide.

As well as removing any protecting group which may be present in R^5', a number of chemical transformation reactions are possible on the final mono-ester or diacid products as previously

described. In each case the product may be obtained as the free carboxylic acid or it may be neutralised with an appropriate base and isolated in salt form. In a variant of the above procedure, compounds of the formula (I) wherein R⁵ is C₁-C₆ alkyl substituted by -NR⁸COR⁹, -NR⁸SO₂R¹⁰, -NR¹¹COCR¹²R¹³R¹⁴ or -NR¹¹SO₂CR¹²R¹³R¹⁴ are prepared by a process which involves acylating or sulphonylating a compound of the formula:

wherein R²⁰ is as defined for R⁸ or R¹¹, R¹⁸ and R^3' are as previously defined and Y is a C₁-C₆ alkyl group; by reaction with an acid of the formula R⁹CO₂H, R¹⁰SO₃H, R¹²R¹³R¹⁴CCO₂H, or

R¹²R¹³R¹⁴CSO₃H, or an activated derivative thereof. The resulting amide or sulphonamide product is then deprotected if required and the mono- or diester product cleaved to yield the carboxylic acids of formula (I) wherein R is H and R³ is CH₂OH or CO₂H as

previously described.

The compounds of formula (VI) are prepared following the procedures shown in Scheme 1 but using a compound of formula (III) having R^5' as a protected amine derivative. Thus, for example R^5' can contain a bis-[(1S)-phenylethyl]aminomethyl substituent.

Hydrogenation of the coupled product gives the corresponcling free amine of formula (VI) wherein R²⁰ is H and Y is CH₂. This route is of particular value for the preparation of compounds having

2(S) stereochemistry in the glutaramide backbone. The starting cycloalkyl-substituted glutaric acid mono esters of formula III may be prepared as described in our European patent applications EP-A-0274234, 89305180.5 and 89304698.7.

The amines of formula (IV) are generally known compounds or they are prepared by appropriate synthetic procedures in accordance with literature precedents. Thus in one procedure the compounds of formula (IV) wherein R³ is CH₂OH may be prepared by reduction of the corresponding acid, or lower alkyl ester for example using sodium borohydride.

Appropriate coupling and protecting methods for all of the above steps and alternative variations and procedures will be well known to those skilled in the art by reference to standard text books and to the examples provided hereafter.

As previously mentioned, the compounds of the invention are potent inhibitors of the neutral endopeptidase (E.C.3.4.24.11). This enzyme is involved in the breakdown of a number of peptide hormones and, in particular, it is involved in the breakdown of atrial natriuretic factor (ANF). This hormone consists of a family of related natriuretic peptides, secreted by the heart, of which the major circulating form in humans is kncwn to be the 28 amino-acid peptide referred to as alpha-hANP. Thus, by preventing the degradation of ANF, by endopeptidase E.C.3.4.24.11, the compounds of the invention can potentiate its biological effects and the compounds are thus diuretic and natriuretic agents of utility in a number of disorders as previously described.

Activity against neutral endopeptidase E.C.3.4.24.11 is assessed using a procedure based on the assay described by J.T. Gafford, R.A. Skidgel, E.G. Erdos and L.B. Hersh, Biochemistry, 1983, 32, 3265-3271. The method involves determining the

concentration of co mpound required to reduce by 50% the rate of release of radiolabelled hippuric acid from hippuryl-L- phenylalanyl-L-arginine by a neutral endopeptidase preparation from rat kidney.

The activity of the compounds as diuretic agents is

determined by measuring their ability to increase urine output and sodium ion excretion in saline loaded conscious mice, In this test, male mice (Charles River CD1, 22-28 g) are acclimatised and starved overnight in metabowls. The mice are dosed intravenously via the tail vein, with the test compound dissolved in a volume of saline solution equivalent to 2.5% of body weight. Urine samples are collected each hour for two hours in pre-weighed tubes and analysed for electrolyte concentration. Urine volume and sodium ion concentration from the test animals are c ompared to a control group which received only saline.

For administration to man in the curative or prophylactic treatment of hypertension, congestive heart failure or renal insufficiency, oral dosages of the compounds will generally be in the range of from 4-800 mg daily for an average adult patient (70 kg). Thus for a typical adult patient, individual tablets or capsules contain from 2 to 400 mg of active compound, in a suitable pharmaceutically acceptable vehicle or carrier for administration singly, or in multiple doses, once or several times a day. Dosages for intravenous administration would typically be within the range 1 to 400 mg per single dose as required. In practice the physician will determine the actual dosage which will be most suitable for an individual patient and it will vary with the age, weight and response of the particular patient. The above dosages are exemplary of the average case but there can, of course, be individual instances where higher or lower dosage ranges are merited, and such are within the scope of this

invention.

For human use, the compounds of the formula (I) can be administered alone, but will generally be administered in

admixture with a pharmaceutical carrier selected with regain to the intended route of administration and standard pharmaceutical practice. For example, they may be administered orally in the form of tablets containing such excipients as starch or lactose, or in capsules or ovules either alone or in admixture with excipients, or in the form of elixirs or suspensions containing flavouring or colouring agents. They may be injected

parenterally, for example, intravenously, intramuscularly or subcutaneously. For parenteral administration, they are best used in the form of a sterile aqueous solution which may contain other substances, for example, enough salts or glucose to make the solution isotonic with blood.

The compounds may be administered alone but may also be administered together with such other agents as the physician shall direct to optimise control of blood pressure or to treat congestive heart failure, renal insufficiency or other disorders in any particular patient in accordance with established medical practice. Thus the compounds can be co-administered with a variety of cardiovascular agents, for example with an ACE inhibitor such as captopril or enalapril to facilitate the control of blood pressure in treatment of hypertension; or with digitalis, or another cardiac stimulant, or with an ACE inhibitor, for the treatment of congestive heart failure. Other possibilities include co-administration with a calcium antagonist (e.g.

nifedipine, amlodopine or diltiazem) a bete-blocker (e.g.

atenolol) or an alpha-blocker (e.g. prazosin or doxazosin) as shall be determined by the physician as appropriate for the treatment of the particular patient or condition involved.

In addition to the above, the compounds may also be

administered in conjunction with exogenous ANF, or a derivative thereof or related peptide or peptide fragment having

diuretic/natriuretic activity or with other ANF-gene related peptides (e.g. as described by D. L. Vesely et al, Biochem.

Bicphys. Res. Comm., 1987, 143, 186).

Thus in a further aspect the invention provides a

phaπtaceutical composition comprising a compound of the formula (I), or a pharmaceutically acceptable salt thereof or bioprecursor therefor, together with a pharmaceutically acceptable diluent or carrier.

The invention also includes a compound of the formula (I), or a pharmaceutically acceptable salt thereof or bioprecursor therefor, for use in medicine, particularly for use as a diuretic agent for the treatment of hypertension, congestive heart failure or renal insufficiency in a human being.

The invention further includes the use of a compound of the formula (I) for the manufacture of a medicament for the treatment of hypertension, heart failure, angina, renal insufficiency, premenstrual syndrome, cyclical oedema, Mesnieres disease, hyperaldosteronism, pulmonary oedema, ascites, hypercalciuria, glaucoma, asthma, inflammation, pain, epilepsy, affective disorders, dementia and geriatric confusion, obesity,

gastrointestinal disorders (including diarrhoea), hyperreninaemia, leukaemia, and the modulation of gastric acid secretion.

The preparation of the compounds of the invention will now be more particularly illustrated by reference to the following experimental Examples. The purity of compounds was routinely monitored by thin layer chromatography using Merck Kieselgel 60 F₂₅₄ plates. ¹H-Nuclear magnetic reasonance spectra were recorded using a Nicolet QE-300 spectrometer and were in all cases consistent with the proposed structures.

EXAMPLE 1

2-{1-[2(R,S)-Carboxy-4-phenylbutyl]cyclopentylcarbonylamino}- 2,3-dihydroindene-2-carboxylic acid

(a) 2-Amino-2,3-dihydroindene-2-carboxylic acid, benzyl ester

A mixture of 2-amino-2,3-dihydroindene-2-carboxylic acid hydrochloride (R. M. Pinder, B. H. Butcher, D. A. Buxton and D J Howells, J. Med. Chem., 1971, 14, 892), (11.33 g, 0.053 m), benzyl alcohol (27.5 ml, 0.27 m), para-toluenesulphonic acid monohydrate (12.1 g, 0.064 m) and benzene (150 ml) was boiled under reflux with continuous removal of water using a Dean-Stark trap. After 48 hours, further quantities of benzyl alcohol (27.5 ml, 0.27 m) and benzene (100 ml) were added, and the reaction allowed to continue under reflux for a further 72 hours. The cool reaction mixture was diluted with diethyl ether and the resulting white precipitate collected by filtration and washed with diethyl ether. The crude tosylate salt was then dissolved in water and this solution basified with 1M aqueous sodium hydroxide solution, then extracted with ethyl acetate. The combined extracts were washed with saturated brine, dried (anhydrous Na₂SO₄) and filtered. Evaporation under vacuum of the filtrate gave an oil (7.6 g, 53.6 %) which solidified at room temperature over-night. Crystallisation of a sample from hexane afforded the pure product as a white solid, m.p. 55-55.5°C. Found: C,75.98; H,6.38; N,5.18.

C₁₇H₁₇NO₂ requires C,76.38; H,6.41; N,5.24% (b) 2-{1-[2(R,S)-Εthoxycarbonyl-4-phenylbutyl]cyclopentyl- carbonylamino}-2,3-dihydr oindene-2-carboxylic acid, benzyl ester

Qxalyl chloride (470 mg, 3.74 mmol) was added at room temperature to a stirred solution of 1-[2(R,S)-ethoxycarbonyl-4- phenylbutyl]cyclopentane carboxylic acid (600 mg, 1.87 mmol) in dry dichloromethane (10 ml) containing dry dimethylformamide (2 drops). After 2 hours the solvent was removed under vacuum and the residual oxalyl chloride evaporated azeotropically using dry dichloromethane (3 x 10 ml).

The crude acid chloride was dissolved in dry dichloromethane (15 ml), then the resulting solution added dropwise to a stirred, ice-cold solution of the product from step (a) (500 mg, 1.87 mmol) and dry triethylamine (210 mg, 2.06 mmol) in dry dichloromethane (25 ml); stirring was continued for 1 hour at 0ºC, then for 16 hours at room temperature. The reaction mixture was diluted with dichloromethane (60 ml), washed successively with water, 1M hydrochloric acid, water, saturated aqueous sodium bicarbonate solution and water, dried (anhydrous Na₂SO₄) and filtered.

Evaporation under vacuum of the filtrate afforded a brown gum (880 mg) which was purified by chromatography on silica gel using an ethyl acetate in hexane elution gradient (0-25%). Evaporation under vacuum of the appropriate fractions provided the required product as a clear oil, which subsequently formed a white waxy solid; crystallisation from diethyl ether-hexane gave the pure product (437 mg, 41.1%), m.p. 89-90°C. Found: C,76.21; H,7.22; N,2.48. C₃₆H₄₁NO₅ requires C,76.16; H,7.28; N,2.47%. 2-{1-[2 (R,S)-Carboxy-4-phen ylbutyl]cyclopentylcarbonylamino}- 2,3-dihyd roin dene-2-c arboxylic acid

(c) A 1M aqueous solution of sodium hydroxide (5 ml, 5 mmol) was added at room temperature to a stirred solution of the above product (430 mg, 0.76 mmole) in 1,4-dioxan (10 ml) and methanol (2.5 ml). After 5 days, the reaction mixture was diluted with water (40 ml), its pH adjusted to 7 with 2M hydrochloric acid, and the organic solvents removed by evaporation under vacuum. The resulting mixture was washed with diethyl ether, acidified to pH 2 with 2M hydrochloric acid, then extracted with ethyl acetate. The combined extracts were washed with saturated brine, dried

(anhydrous Na₂SO₄), filtered, and evaporated under vacuum.

Crystallisation of the residue from ethyl acetate-hexane gave the required product as a white solid (200 mg, 56.6%). Found:

C,71.30; H,6.88; N.3.25. C₂₇H₃₁NO₅; 0.17 CH₃CO₂C₂H₅ requires C,71.59; H,7.02; N,3.02%.

EXAMPLE 2

2-{1-[2 (R,S)-Carboxy-4-m ethoxybutyl]c yclopentylcarbonyl- a_mino}-2 ,3-dihydroindene-2-carboxylic acid

(a) 2-{1-[2(R,S)-Benzyloxycarbonyl-4-m ethoxybutyl]cyclopentyl- carbonyla m i no}-2,3-dih ydroindene-2-carboxylic acid, benzyl ester

The procedure of Example 1(b) was followed using 1-[2 (R,S)- benzyloxycarb onyl-4- methoxybutyl]cyclopentane carboxylic acid (334 mg, 1 mmole) and 2-amino-2,3-di hydroindene-2-carboxylic acid benzyl ester (267 mg, 1 mmol) , to furnish the required diester (430 mg, 72.5%) . Found: C,72.95; H,7.03 ; N,3.08. C_{3 6}H₄₁NO₆; 0.5 H₂O requires C,72.75; H,7.14; N,2.36%. (b) 2-{1-[2 (R,S)-Carboxy-4-methoxy butyl]cyclopentylcarbonyl- amino}-2 ,3-di hydroi n dene-2-carboxylic acid

A solution of the above product (390 mg, 0.67 mmol) in ethanol (20 ml) was hydrogenated over 10% palladium on charcoal (39 mg) at 15 p.s.i. (1 bar) and room temperature for 1 hour. The catalyst was removed by filtration through a pad of Arbocel

(upper) and Hyflo (lower), then the filtrate evaporated under vacuum, and residual ethanol removed azeotropically with

dichloromethane to provide the required product as a white solid (235 mg, 87.2%), m.p. 142-144°C. Found: C,65.17; H,7.29; N,3.32. C₂₂H₂₉NO₆ requires C,65.49; H,7.25; N,3.47%.

EXΑMPLE 3

2-{1-[2 (R,S_ -Carboxy-3-(S-lysyla mino)prepyl]c yclopentyl- carbon ylamino }-2,3-dihydroin dene-2-carboxylic acid

(a) 2-Amino-2,3-dihydroindene-2-ca rboxylic acid, ethyl ester, hydrochloride

A stirred, ice-cold solution of 2-amino-2,3-dihydroindene-2- carbcoylic acid hydrochloride (2.48 g, 11.6 mmol) in absolute ethanol was saturated with dry hydrogen chloride. The resulting suspension was stirred at room temperature overnight, then warmed to 40ºC and treated further with dry hydrogen chloride until a clear solution was obtained (2 hours) . After a further 4 hours at 40ºC, the reaction mixture was evaporated to dryness under vacuum, then the residue crystallised from ethanol-diethyl ether to give the pure product (2.41 g, 85.8%) , m.p. 189-193°C. Found: C,59.74; H,6.69; N,5.76. C₁₂H₁₅NO₂ ; HCl requires C,59.63; H,6.67; N,5.79%. (b) 2-{1[2(R,S)-tert-Butoxycarbonyl-3-(dibenzylamino)propyl]- cyclopentylcarbonylamino}-2,3-dihydroindene-2-carboxylic acid, ethyl ester

To a stirred, ice-cold solution of 2(R,S)-tert-butoxycarbonyl- 3-(dibenzylamino)propylcyclopentane carboxylic acid hydrochloride (7.84 g, 0.016 m), 1-hydroxybenzotriazole (2.16 g, 0.016 m) and 4-methylmorpholine (4.86 g, 0.048 m) in dry dichloromethane (100 ml) was added 1-(3-dimethylaminopropyl)-3-ethylcarabodiimide hydrochloride (6.13 g, 0.032 m); stirring was continued for 1 hour at 0ºC, then for 16 hours at room temperature. The

dichloromethane was removed by evaporation under vacuum at room temperature, and the residue partitioned between diethyl ether and water. The ether phase was separated, washed with water, dried (anhydrous Na₂SO₄) and filtered; subsequent evaporation under vacuum at room temperature of the filtrate provided the crude activated ester (9.33 g, 95.4%) as a hemi-solvate with

dichloromethane, of sufficient purity for further progression.

To a stirred solution of this activated ester (3.24 g, 5.3 mmol) in dry dichloromethane (40 ml) at 0°C was added

2-amino-2,3-dihydroindene-2-carboxylic acid ethyl ester (1.09 g, 5.3 mmol) and 4-dimethylaminopyridine (0.71 g, 5.8 mmol). After 0.5 hours the solvent was removed by evaporation under vacuum and the resulting viscous oil allowed to stand at room temperature for 3 days before partitioning between diethyl ether and water. The ether phase was separated, washed with water, dried (anyhdrous MgSO₄) and filtered. Evaporation under vacuum of the filtrate furnished an oil which was purified by chromatography on silica gel using a dichloromethane in hexane elution gradient (20-100%). Evaporation of the appropriate fractions provided the required product (2.10 g, 61.2%). Found: C,73.92; H,7.88; N,4.55.

C₄₀H₅₀N₂O₅0.5 H₂O requires C,74.15; H,7.94; N,4.33%.

(c) 2-{1-[3-Amino-2(R,S)-tert-butoxycarbonylpropyl]cyclopentyl- carbonylamino}-2,3-dihydroindene-2-carboxylic acid, ethyl ester

A solution of the above diester (2.7 g, 4.2 mmol) in a mixture of ethanol (6 ml) and water (0.5 ml) was hydrogenated over 20% palladium hydroxide on charcoal (270 mg) at 50 p.s.i. (3.45 bar) and room temperature for 16 hours. The catalyst was removed by filtration through a pad of Arbooel (upper) and Hyflo (lower), then the filtrate evaporated under vacuum, and residual solvents removed azeotropically with dichloromethane, to afford the required product (1.92 g, 99.6%). Pound: C,67.64; H,8.44; N,5.89. C₂₆H₃₈N₂O₅ requires C,68.09; H,8.35; N,6.11%.

(d) 2-{1-[2(R,S)-tert-Butyloxycarbonyl-3-(N², N⁶-di-benzyloxy- carbonyl-S-lysyl-amino)propyl]cyclopentylcarbonylamino}-2,3- dihydroindene-2-carboxylic acid, ethyl ester

1-(3-Dimethylaminopropyl)-3-ethlcarbodiimide hydrochloride

(944 mg, 4.92 mmol) was added to a stirred solution of the above amino (1.13 g, 2.46 mmol), 1-hydroxybenzotriazole (322 mg, 2.46 mmol), N², N⁶-di-benzyloxycarbonyl-S-lysine (1.02 g, 2.46 mmol) and 4-methylmorpholine (746 mg, 7.38 mmol) in dry dichloromethane (25 ml) at 0ºC. Stirring was continued for 0.5 hours at 0°C, then for 16 hours at room temperature, before removal of the solvent under vacuum. The residue was partitioned between diethyl ether and water, then the ether phase washed with 1M hydrochloric acid and water, dried (anhydrous Na₂SO₄) and filtered. Evaporation under vacuum of the filtrate, followed by chromatography of the residual oil on silica gel using a diethyl ether in hexane elution gradient (0-50%), gave the required product (1.30 g, 61.8%).

Found: C,67.31; H,7.40; N,6.09. C₄₈H₆₂N₄O₁₀ requires C,67.42; H,7.31; N,6.55%.

(e) 2-{1-[2(R,S)-Carboxy-3-(N², N⁶-di-benzyloxycarbonyl-S-lysyl- amino)propyl]cyclopentylcarbonylamino}-2,3-dihydroindene-2- carboxylic acid, ethyl ester

Trifluoroacetic acid (5 ml) was added dropwise to a stirred solution of the above product (1.28 g, 1.5 mmol) in dry

dichloromethane (10 ml) at 0ºC. The ice-bath was removed, stirring continued for 1 hour at room temperature, then the reaction mixture evaporated under vacuum. The crude product was dissolved in ethyl acetate and residual trifluoroacetic acid removed by washing the solution with saturated aqueous sodium bicarbonate solution. Drying (anhydrous Na₂SO₄), filtration and evaporation under vacuum of the ethyl acetate solution, followed by azeotropic removal of residual solvent with dichloromethane, afforded the required product (1.12 g, 90.4%). Found: C,63.85; H,6.66; N,6.59. C ₄₄H₅₄N₄O₁₀; 1.5 H₂O requires C,63.98; H,6.96; N,6.78%.

(f) 2-(1-[2(R,S)-Carboxy-3-(S-lysylamino)propyl]cyclopentyl- carbonylamino}-2,3-dihydroindene-2-carboxylic acid, ethyl ester

A solution of the above product (1.10 g, 1.33 mmol) in a mixture of ethanol (7 ml) and water (0.5 ml) was hydrogenated over 10% palladium on charcoal (110 mg) at 60 p.s.i. (4.1 bar) and room temperature for 16 hours. Work-up as described above for Example 2 (b) provided the required product as a beige foam (740 mg, 98.9%). Found: C,59.98; H,7.56; N,9.52. C₂₈H₄₂N₄O₆; 1.75 H₂O requires C,59.82; H,8.16; N,9.97%. (g) 2-{1-[2(R,S)-Carboxy-3-(S-lysyla mi no)propyl]cyclopentyl- car bon yl amin o}-2 ,3-d ihydroi ndene-2-carboxylic acid

A solution of the above ester (700 mg, 1.24 mmol) in 1M aqueous sodium hydroxide solution (7.5 ml, 7.5 mmol) was allowed to stand at room temperature for 16 hours, then loaded onto a column of strongly acidic ion-exchange resin. The column was washed to neutrality using distilled water, then eluted with 5% aqueous pyridine. Evaporation under vacuum of the appropriate foactions gave a glass which was dissolved in distilled water; freeze drying of this aqueous solution provided the required product (370 mg, 55.4%). Found: C,57.58; H,7.95; N,10.31.

C₂₆H₃₈N₄O₆; 2H₂O requires C,57.97; H,7.86; N,10.40%.

EXAMPLE 4

2-{1-[3-(N²-Acetyl-S-lysylamino)-2(R,S)-carboxypropyl]cyclo- pentyl carbonylamino}-2,3-dihydroi nde ne-2-carboxylic acid

The pro cedure of Example 3 was followed but using

N²-aoetyl-N⁶-tenzyloxycarbonyl-S-lysine in step (d) . Deprotection gave the title co mpound. Found: C,58.30; H,7.58; N,10.07.

C₂₈H₄₀N₄O₇; 1.75 H₂O requires C,58.36; H,7.61; N,9.72%.

EXAMPLE 5

2-(1-[2(R,S)-Carboxy-3-(N²-methanesulphonyl-S-lysylamino)- propyl]cyclopentylcarbonyla mi no}-2,3-dihydroindene-2-carboxylic acid

The procedure of Example 3 was followed but using N⁶- ben zyloxyca rbo nyl-N²-methanesulponyl-S-lysine in step (d) .

Deprotection gave the title compound. Found: C,53.99; H,7.13; N,9.31. C₂₇H₄₀N₄O₈S; H₂O requires C,54.17; H,7.07; N,9.36%. EXAMPLE 6

2-{1-[2(S)-Carboxy-3-(S-lysylamino)propyl]cyclopentyl- carbonylamin o}-2,3-dihydroindene-2-carboxylic acid

(a) 2-{1-[2(S)-tert-Butoxycarbonyl-3-{(S,S)-alpha, alpha¹- dimethyldibenzylamino}propyl]cyclopentylcarbonylamino}-2,3- dihydroindene-2-carboxylic acid, ethyl ester

The procedure of Example 3 was followed but using 1-{2(S)- tert-butoxycarbonyl-3-[(S,S)-alpha, alpha¹-1-dimethyldibenzyl- amino)prcpyl]cyclopentane carboxylic acid in step (b) to give the title product, in 79.1% yield. Found: C, 75.45; H,8.30; N,4.01. C₄₂H₅₄N₂O₅ requires C,75.64; H,8.16; N,4.20%.

(b) 2-{1-[3-Amino-2(S)-tert-butoxycarbonylpropyl]cyclopentyl- carbonylamino}-2,3-dihydroindene-2-carboxylic acid, ethyl ester

Hydrogenation of the above product as described in Example 3(c) gave the 2(S) isomer of the amine in 99.1% yield. Rf

(silica) 0.50 (dichloromethane-methanol, 9:1).

(c) 2-{1-[2(S)-Carboxy-3-(S-lysylamino)propyl]cyclopentyl- carbonylamino}-2,3-dihydroindene-2-carboxylic acid

The above amine was coupled to N², N⁶-di-benzyloxycarbonyl-S- lysine following the proc edure of Example 3(d) and the product deprotected as described in Example 3 steps (e) to (g) to give the title compound. Found: C,56.71; H,7.48; N,9.16. C₂₆H₃₈N₄O₆; 2.5 H₂O requires C,57.02; H,7.91; N,10.23%. EXAMPLE 7

2-{1-[2(S)-Carboxy-3-(N²- meth anesulphonyl-S-lysylamino)- propyl]cyclcpentylcarbonylamino}-2,3-dihydr oindene-2-carboxylic acid

The procedure of Example 6 was followed but using N⁶- ben zyloxy-carbonyl-N ²-methanesulphonyl-S-lysine in the coupling step to give the title compound. Found: C,53.60; H,7.27; N,8.82.

C₂₇H₄₀N₄O₈S; 1.5 H₂O requires C,53.36; H,7.13; N,9.22%.

EXAMPLE 8

2-{1-[2 (R,S) -C ar boxypentyl] cyclopentylcarbonylamino}-2- hydroxymethyl-2,3-dihydroindene

(a) 2-Am ino-2-hydroxym ethyl-2,3-d ihydroindene

A solution of 2-amino-2,3-dihydroindene-2-carboxylic, ethyl ester, hydrochloride (1.7 g, 7.03 mmol) in 50% aqueous ethanol (15 ml), was added dropwise to a stirred, ice-cold solution of sodium borohydride (1.11 g, 29.4 mmol) in 50% aqueous ethanol (35 ml), then the reaction mixture heated under reflux for 3 hours.

The bulk of the ethanol was removed by evaporation under vacuum, and the residual suspension saturated with sodium chloride then extracted with ethyl acetate. The combined extracts were washed with saturated brine, dried (anhydrous MgSO₄), filtered and evaporated under vacuum. Crystallisation of the resulting white solid (1.05 g) from ethyl acetate-hexane afforded the required product (0.99 g, 84.8%), m.p. 89.5-90.5°C. Found: C,72.32;

H,8.02; N,8.17. C₁₀H₁₃NO; 0.15 H₂O requires C,72.39; H,8.08;

N,8.44%.

(b) 2-{1[(R,S)-Benzyloxycarbonylpentyl]cyclopentylcarbonylamino}- 2-hydroxymethyl-2,3-dihydroindene 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (767 mg, 4 mmol) was added to a stirred, ice-cold mixture of 1- [2(R,S)-benzyloxycarbonylpentyl]cyclopentane carboxylic acid (637 mg, 2 mmol), 1-hydroxybenzotriazole (270 mg, 2 mmol),

4-methylmorpholine (202 mg, 2 mmol), the product from step (a) above (332 mg, 2 mmol) and dry dichloromethane (10 ml). Stirring was continued for 0.5 hours at 0ºC, then for 24 hours at room temperature.

The dichloromethane was removed by evaporation under vacuum, and the residue partitioned between diethyl ether and water. The ether phase was separated, washed with water, 1M hydrochloric acid, water, saturated aqueous sodium bicarbonate solution and water, then dried (anhydrous MgSO₄) and filtered. Evaporation under vacuum of the filtrate furnished an oil which was purified by chromatography on silica gel using diethyl ether-hexane (1:1) as eluent. Evaporation under vacuum of the appropriate fractions provided the required product (180 mg, 19.0%). Found: C,73.75; H,7.84; N,3.06. C₂₉H₃₇NO₄; 0.5 H₂O requires C,73.69; H,8.10;

N,2.96%.

(c) 2-{1-[2(R,S)-Carboxypentyl]cyclopentylcarbonylamino}-2- hydroxymethyl-2,3-dihydroindene

A solution of the above product (170 mg, 0.36 mmol) in a mixture of ethanol (20 ml) and water (1 ml), was hydrogenated over 5% palladium on charcoal at 50 p.s.i. (3.45 bar) and room temperature, to give the title product as a white solid (115 mg, 83.5%), m.p. 126-128°C, after trituration with diethyl ether- hexane (1:1). Found: C,69.04; H,8.15; N,3.63. C₂₂H₃₁NO₄; 0.5 H₂O requires C,69.08; H,8.43; N,3.66%. EXAMPLE 9

2-{1-[2 (R,S)-Carboxy-4-ph enylbutyl]cyclopentylcarbonylamino}- 2-hydroxymethyl-2 ,3-dihydroindene

(a) 2-{1-[2 (R,S) -Benzyloxycarbo nyl-4-phenylbutyl]cyclopentyl- carbonylamino}-2-hydroxymethyl-2,3-dihydroindene

The procedure of Example 8(b) was followed using 1-[2 (R,S)- benzyloxycarbonyl-4-phenylbutyl]cyclopentanecarboxylic acid as starting material and allowing the reaction mixture to stand at room temperature for a further 5 days. The required product was obtained as an oil (19.9%) . Rf (silica) 0.15 (diethyl ether- hexane, 1:1) .

(b) 2-{1-[2 (R,S)-Carboxy-4-p hen y lbutyl]cyclopentylcarbonylamino}- 2-hydroxymethyl-2,3-dihydroindene

Hydrogenation of the above product as described in Example 8(c) , followed by chromatography on silica gel using ethyl acetate as eluent and evaporation under vacuum of the appropriate

fractions, followed by trituration of the residue with diethyl ether-hexane (1:4) , gave the required product (62.4%) as a white solid, m.p. 140-143°C. Found: C,73.76; H,7.62; N,3.12.

C₂₇H₃₃NO₄; 1/4 H₂O requires C,73.69; H,7.67; N,3.18%.

EXAMPLE 10

2-{1-[2 (R,S)-C arboxy-3-(S-lysylam ino)propyl]cyclopentyl- carbo nylamino}-2-hydroxymethyl-2,3-dihydroindene

(a) 2-{1-[2 (R,S)-tert-Butoxycarbonyl-3-(dibenzylamino )propyl] cyclopentylcarbon yla mino}-2-hydroxymethyl-2,3-dihydroindene

4-Methylmorpholine (1.78 g, 17.6 mmol) was added to a stirred solution of the N-hydroxy benzot riazole-derived activated ester hemi-solvate with dichloromethane of 2(R,S)-tert-butoxycarbonyl-3- (dibenzylamino)propylcyclcpentane carboxylic acid (Example 3b) (9.78 g, 16 mmol) and 2-a m ino -2-hydroxymethyl-2,3-di hydro indene (2.65 g, 16 mmol) in dry dichloromethane (50 ml) at room

temperature. After 2 hours the solvent was removed by evaporation under vacuum and the residue allowed to stand at room temperature for 2 days before being partitioned between diethyl ether and water. The ether phase was separated, washed with water, dried (an hydrous MgSO₄) and filtered. Evaporation under vacuum of the filtrate, followed by purification of the residue by

c h ro matography on silica gel using a dichloro methane in hexane elution gradient (20-100%) , afforded the required product (3.30 g, 33.6%) . Found: C, 75.09; H,8.02; N,4.69. C₃₈H₄₈N₂O₄, 0.2 CH₂Cl₂ requires C,74.75; H,7.95; N,4.57%.

(b) 2-{1-[3-Am ino-2(R,S)-tert-b utoxyca rbonylpropyl]cyclopentyl- carbonylamino}-2-hydroxymethyl-2,3-d ihydroindene

The above product was hydrogenated as described in Example 3 (c) to give the title amine in 98.2% yield. Found: C,68.96;

H,8.88; N,6.63. C₂₄H₃₆N₂O₄ requires C,69.20; H,8.71; N,6.73%.

(c) 2-{1-[2 (R,S)-tert-Butoxycarbonyl-3-(N², N⁶-di-benzyloxy- carbon yl-S-lysylam ino)propyl]cyclopentylcarbonylamino}-2-hydroxy- methyl-2,3-di hydroindene

The above amine was coupled to N², N ⁶-dibenzyloxycarbonyl-S- lysine following the pro cedure of Exa mple 3 (d) but using a gradient of diethyl ether-hexane (1:8 to 1:1) followed by ethyl acetate as eluents for c hro matographic purification to give the product in 62.0% yield. Found: C,67.59; H,7.53; N,6.75.

C₄₆H₆₀N₄O₉ requires C,67.96; H,7.44; N,6.89%. (d) 2-{1-[2(R.S)-Carboxy-3-(N², N⁶-di-benzyloxycarbonyl-S-lysyl- amino)propyl]cyclopentylcarbonylamino}-2-hydroxymethyl-2,3- dihydroindene

A stirred, ice-cold solution of the above product (1.24 g, 1.52 mmol) in dry dichloromethane (20 ml) was saturated with dry hydrogen chloride. After a further 2 hours at 0ºC, the reaction mixture was evaporated under vacuum and the residue azeotroped with dichloromethane to provide the title product as a white foam (1.05 g, 85.3%). Found: C,64.28; H,6.83; N,7.21. C₄₂H₅₂N₄O₉; 1.5 H₂O requires C,64.35; H,7.07; N,7.15%.

(e) 2-{1-[2(R,S)-Carboxy-3-(S-lysylamino)propyl]cyclopentyl- carbonylamino}-2-hydroxymethyl-2,3-dihydroindene

The above product was hydrogenated following the procedure of Example 3(f) to give the required title acid as a white foam (79.7%). Found: C,61.20; H,8.14; N,10.41. C₂₆H₄₀N₄O₅; 1.25 H₂O requires C,61.09; H,8.38; N,10.96%.

EXAMPLE 11

2-{1-[2(S)-Carboxy-3-(N²-meth anesulphonyl-S-lysylamino)- propyl]cyclopentylcarbonylamino}-2-hydroxymethyl-2,3-dihydroindene

The procedure of Example 10 was followed but losing the N-hydroxybenzotriazole-derived activated ester of 2(S)-tert- butyloxycarbonyl-3-[(S,S)-alpha, alpha ¹-dimethyldibenzylamino]- propylcyclopentane carboxylic acid as starting material in step (a) and coupling with N⁶-tert-butyloxycarbonyl-N²-methane- sulphonyl-S-lysine in step (c). Deprotection as previously described gave the product which was dissolved in a little distilled water and freeze dried to give the title product as a white solid. Found: C,51.50; H,7.38; N,8.67. C₂₇H₄₂N₄ O₇S; HCl; 1.5 H₂O requires C,51.46; H,7.36; N,8.89%.

Claims

1. A compound having the formula-:

(I) wherein A completes a 4 to 7 membered carbocyclic ring which may be saturated or mono-unsaturated and which may optionally be fused to a further saturated or unsaturated 5 or 6 membered carbocyclic ring ; R is H, C₁-C₆ alkyl, benzyl or an alternative biolabile ester-forming group;

R¹ is H or C₁-C₄ alkyl;

R is H, OH, C₁-C₄ alkyl, C₁-C₄alkoxy, halo or CF₃;

R³ is CH₂OH or CO₂R⁴ wherein R⁴ is as previously defined for R;

and R⁵ is C₁-C₆ alkyl, C₂-C₆ alkenyl, C₂-C₆ alkynyl,

C₃-C₇ cycloalkyl, or C₃-C₇ cycloalkenyl,

or R⁵ is C₁-C₆ alkyl substituted by halo, hydroxy, C₁-C₆

1 6 alkoxy, C₁-C₆ alkoxy(C₁-C₆)alkoxy, C₃-C₇ cycloalkyl, C₃-C₇ cycloalkenyl, aryl, aryloxy, heterocyclyl, -NR⁶R⁷, -NR⁸COR⁹, -NR⁸SO₂R¹⁰, -CONR⁶R⁷ or R⁶R⁷N-(C₁-C₆)alkoxy; or R is C₁-C₆ alkyl substituted by a group of the formula:

or

wherein R⁶and R⁷ are each independentlyH, C₁-C₄ alkyl, C₃-C₇ cycloalkyl, aryl, aryl(C₁-C₄)alkyl, C₂-C₆ alkoxyalkyl, or heterocyclyl; or the two groups R⁶and R⁷ are taken together with the nitrogen to which they are attached to form a pyrrolidinyl, piperidino, morpholino, piperazinyl or N-(C₁-C₄)alkyl-piperazinyl group;

R⁸ is H or C₁-C₄ alkyl;

R is C₁-C₄ alkyl, CF₃, aryl, aryl(C₁-C₄)alkyl, aryl(C₁-C₄)alkoxy, heterocyclyl, C₁-C₄ alkoxy or NR⁶R⁷ wherein R⁶ and R⁷are as previously defined; R¹⁰ is C₁-C₄ alkyl, C₃-C₇ cycloalkyl, aryl or heterocyclyl;

R¹¹ is H, C₁-C₆ alkyl, aryl or C₃-C₇ cycloalkyl;

R¹² is R¹¹CONR¹¹-, R¹¹SO₂NR¹¹-, R¹⁶R¹⁷N-(CH₂)_p-, or

R¹¹0-, wherein each R¹¹ is as previously defined above; R¹³ and R¹⁴ are each independently H or C₁-C₆ alkyl; or R¹³ is H and R¹⁴ is C₁-C₆ alkyl which is substituted by

CH, C₁-C₄alkoxy, SH, SCH₃, NH₂, aryl(C₁-C₆)alkyl-

OCONH-, NH₂CO-, CO₂H, guanidino, aryl, or heterocyclyl; or the two groups R¹³ and R¹⁴ are joined together to form, with the carbon atom to which they are attached, a

5 or 6 membered carbocyclic ring which may be saturated or mono-unsaturated and which may optionally be substituted by C₁-C₄ alkyl or fused to a further 5 or 6 membered saturated or unsaturated carbocyclic ring; or R¹³ is H, and R¹² and R¹⁴ are linked to form a

2-(N-COR¹¹-4-aminopyrrolidinyl) group;

R¹⁵ is R¹⁶R¹⁷NCO-, R¹¹OCO-, R¹¹OCH₂- or heterocyclyl, wherein R¹¹ is as previously defined above;

R¹⁶ and R¹⁷ are each independently H or C₁-C₆ alkyl; and p is 0 or an integer of from 1 to 6;

and pharmaceutically acceptable salts thereof and bioprecursors therefor.

2. A compound according to claim 1 wherein A is (CH₂)₄ and R¹ and R² are H having the formula

wherein R, R³ and R⁵are as previously defined for formula (I).

3. A compound as claimed in claim 1 or claim 2 wherein R is H,

R³ is CO₂R⁴ and R⁴ is H.

4. A compound as claimed in claim 1 or claim 2 wherein R³ is

CO₂R⁴ and one or both of R and R⁴is a biolabile ester- farming group and said group is ethyl, benzyl,1-(2,2-diethyl- butyryloxy)-ethyl, 2-etnylpropionyloxymethyl, 1-(2-ethyl- propionyloxy)ethyl, 1-(2,4-dimethylbenzoyloxy)ethyl,

1-(benzoyloxy)benzyl, 1-(benzoyloxy)ethyl, 2-methyl-1- propionyloxypropyl, 2,4,6-trimethyl-benzoyloxymethyl, 1-

(2,4,6-trimethyl-benzyloxy)ethyl, pivaloyloxymethyl, phenethyl, pherpropyl, 2,2,2-trifluoroethyl, 1- or 2-naphthyl, 2,4-dimethyl- phenyl, 4-t-butyl-phenyl, 5-(4-methyl-1,3-dioxolenyl-2-onyl)- methyl or 5-indanyl.

5. A compound as claimed in any one of claims 1 to 4 wherein R⁵ is methylene substituted by a group of the formula -NHCOCR¹²R¹³R¹⁴, and R¹² is NH₂, R¹¹CONH- or R¹¹SO₂NH-, R¹³ is H and R¹⁴ is

-(CH₂)₄NH₂.

6. A compound as claimed in any one of claims 1 to 4 wherein R⁵ is C₁-C₆ alkyl, C₁-C₆alkyl substituted by C₁-C₆ alkoxy or C₁-C₆ alkyl substituted by phenyl.

7. A compound according to claim 1 wherein said compound is-:

2-{1-[2(S)-carboxy-3-(S-lysylamino)propyl]cyclcpentyl- carbonylamino}-2,3-dihydroindene-2-carboxylic acid,

2-{1-[2(S)-carboxy-3-(N²-methanesulphonyl-S-lysylamino)-- propyl]cyclcpentylcarbonylamino}-2,3-dihydroindene-2-carboxylic acid, or 2-{1-[2(S)-carboxy-3-(N²-methanesulphonyl-S-lysylamino)- propyl]cyclopentylcartonylamino}-2-hydroxymethyl-2,3- dihydroindene; or a biolabile ester derivatives thereof.

8. A process for preparing a coπpound of the formula (I) as claimed in claim 1 which comprises subjecting a compound of the formula-:

wherein A, R¹and R² are as previously defined, R^5' is as defined for R⁵ with any reactive group therein protected if necessary, R¹⁸ is as defined for R excluding H, or is a conventional carboxylic acid protecting group, and R^3' is either CH₂OH or CO₂R¹⁹ wherein R¹⁹ is as previously defined for R⁴ excluding H or is a

conventional carboxylic acid protecting group;

to a hydrolysis and/or hydrogenation and/or other deprotection reaction to remove any protective group present in R^5' and to remove one or both of R¹⁸ and R¹⁹, if present, to yield the corresponding dicarboxylic acid of formula (I) wherein R and R⁴ are both H, or to yield the corresponding mono-ester product wherein one of R and R⁴ is H and the other is a biolabile ester-fonning group; or in the case where R^3' is CH₂OH, to yield the mono-carboxylic acid where R is H; and optionally forming a pharmaceiitically acceptable salt of the product.

9. A process for preparing a compound of the formula (I)

5

wherein R is C₁-C₆alkyl substituted by -NR⁸COR⁹, -NR⁸SO₂R¹⁰, -NR¹¹COCR¹²R¹³R¹⁴ or -NR¹¹SO₂CR¹²R¹³R¹⁴ which comprises acylating or sulphonating a compound of the formula:

wherein R²⁰ is as defined for R⁸or R¹¹, R¹⁸ and R^3' are as previously defined and Y is a C₁-C₆ alkyl group; by reaction with an acid of the formula R⁹CO₂H, R¹⁰SO₃H, R¹²R¹³R¹⁴CCO₂H, or

R¹²R¹³R¹⁴CSO₃H, or an activated derivative thereof, followed by deprotection if required and hydrogenation or hydrolysis of the mono- or diester product to yield the carboxylic acid of formula (I) wherein R is H and R³ is CH₂OH or CO₂H, and optionally forming a pharmaceutically acceptable salt of the product.

10. A process as claimed in claim 8 or claim 9 wherein R¹⁸ and R¹⁹ are independently selected from t-butyl, ethyl and benzyl and said groups are removed by treatment with trifluoroacetic acid, aqueous alkali or catalytic hydrogenation respectively, to yield the compound of formula (I) wherein R and R⁴ (if present) are both

H.

11. A pharmaceutical composition comprising a compound of the formula (I) or (II) as claimed in any one of claims 1 to 7 or a pharmaceutically acceptable salt thereof or bioprecursor therefor, together with a pharmaceutically acceptable diluent or carrier.

12. A compound of the formula (I) or (II) as claimed in any of claims 1 to 7 or a pharmaceutically acceptable salt thereof or bioprecursor therefor, for use in medicine, particularly for the treatment of hypertension, heart failure or renal insufficiency.

13. A process for preparing a compound having the formula- :

(I) wherein A completes a 4 to 7 membered carbocyclic ring which may be saturated or mono-unsaturated and which may optionally be fused to a further saturated or unsaturated 5 or 6 m e mbered carbocyclic ring ; R is H, C₁ -C₆ alkyl, benzyl or an alternative biolabile ester-forming group;

R¹ is H or C₁-C₄ alkyl;

R² is H, OH, C₁-C₄ alkyl, C₁ -C₄ alkoxy, halo or CF₃;

R³ is CH₂OH or CO₂R⁴ wherein R⁴ is as previously defined for R;

and R⁵ is C₁-C₆ alkyl, C₂-C₆ alkenyl, C₂-C₆ alkynyl,

C₃-C₇ cycloalkyl, or C₃-C₇ cycloalkenyl,

or R⁵ is C₁ -C₆ alkyl substituted by halo, hydroxy, C₁-C₆ alkoxy, C₁-C₆ alkoxy(C₁-C₆)alkoxy, C₃-C₇ cycloalkyl, C₃-C₇ cycloalkenyl, aryl, aryloxy, heterocyclyl, -NR⁶ R⁷, -NR⁸COR⁹, -NR⁸SO₂R¹⁰, -CONR⁶R⁷ or R⁶R⁷N-(C₁-C₆ )alkoxy; or R is C₁-C₆ alkyl substituted by a group of the formula:

- or

wherein R⁶and R⁷ are each independently H, C₁-C₄ alkyl, C₃-C₇ cycloalkyl, aryl, aryl(C₁-C₄)alkyl, C₂-C₆ alkoxyalkyl, or heterocyclyl; or the two groups R⁶ and R⁷are taken together with the nitrogen to which they are attached to form a pyrrolidinyl, piperidino, morpholino, piperazinyl or N-(C₁-C₄)alkyl-piperazinyl group;

R⁸ is H or C₁-C₄ alkyl;

R⁹ is C₁-C₄ alkyl, CF₃, aryl, aryl(C₁-C₄)alkyl, aryl(C₁-C₄)alkoxy, heterocyclyl, C₁-C₄ alkoxy or NR⁶R⁷ wherein R⁶ and R⁷ are as previously defined;

R¹⁰ is C₁-C₄ alkyl, C₃-C₇ cycloalkyl, aryl or heterocyclyl;

R¹¹ is H, C₁-C₆ alkyl, aryl or C₃-C₇ cycloalkyl;

R¹² is R¹¹CONR¹¹-, R¹¹SO₂NR¹¹-, R¹⁶R¹⁷N-(CH₂)_p-, or

R¹¹0-, wherein each R¹¹ is as previously defined above; R¹³ and R¹⁴ are each independently H or C₁-C₆ alkyl; or R¹³ is H and R¹⁴ is C₁-C₆ alkyl which is substituted by

CH, C₁-C₄ alkoxy, SH, SCH₃, NH₂, aryl(C₁-C₆)alkyl-

OCONH-, NH₂CO-, CO₂H, guanidino, aryl, or heterocyclyl; or the two groups R¹³ and R¹⁴ are joined together to form, with the carbon atom to which they are attached, a

5 or 6 membered carbocyclic ring which may be saturated or mono-unsaturated and which may optionally be substituted by C₁-C₄ alkyl or fused to a further 5 or 6 membered saturated or unsatorated carbocyclic ring; or R¹³ is H, and R¹² and R¹⁴ are linked to form a

2-(N-COR¹¹-4-aminopyrrolidinyl) group;

R¹⁵ is R¹⁶R¹⁷NCO-, R¹¹OCO-, R¹¹OCH₂- or heterocyclyl, wherein R¹¹ is as previously defined above;

R¹⁶ and R¹⁷ are each independently H or C₁-C₆ alkyl; and p is 0 or an integer of from 1 to 6;

which comprises subjecting a compound of the formula:

wherein A, R¹and R²are as previously defined, R^5' is as defined for R⁵ with any reactive group therein protected if necessary, R¹⁸ is as defined for R excluding H, or is a conventional carboxylic acid protectαng group, and R^3' is either CH₂OH or CO₂R¹⁹ wherein

R¹⁹ is as previously defined for R⁴excluding H or is a

conventional carboxylic acid protecting group;

to a hydrolysis and/or hydrogenation and/or other deprotection reaction to remove any protective group present in R^5' and to remove one or both of R¹⁸and R¹⁹, if present, to yield the corresponding dicarboxylic acid of formula (I) wherein R and R⁴ are both H, or to yield the corresponding mono-ester product wherein one of R and R⁴is H and the other is a biolabile

ester-forming group; or in the case where R^3' is CH₂OH, to yield the mono-carboxylic acid where R is H, and optionally forming a pharmaceutically acceptable salt of the product.

14. A process for preparing a compound of the formula (I) wherein R⁵ is C₁-C₆ alkyl substituted by -NR⁸COR⁹, -NR⁸SO₂R¹⁰,

-NR¹¹COCR¹²R¹³R¹⁴ or -NR¹¹SO₂CR¹²R¹³R¹⁴ which comprises acylating or sulphorating a compound of the formula:

wherein R²⁰ is as defined for R⁸ or R¹¹, R¹⁸ and R^3' are as previously defined and Y is a C₁-C₆ alkyl group; ty reaction with an acid of the formula R⁹CO₂H, R¹⁰SO₃H, R¹²R¹³R¹⁴CCO₂H, or

R¹²R¹³R¹⁴CSO₃H, or an activated derivative thereof, followed by deprotection if required and hydrogenation or hydrolysis of the mono- or diester product to yield the carboxylic acid of formula (I) wherein R is H and R³ is CH₂OH or CO₂H; and optionally forming a pharmaceutically a∞eptable salt of the product.

15. A process as claimed in claim 13 or claim 14 wherein R¹⁸ and R¹⁹ are independently selected from t-butyl, ethyl and benzyl and said groups are removed by treatment with trifluoroacetic acid, aqueous alkali or catalytic hydrogenation respectively, to yield the compound of formula (I) wherein R and R⁴ (if present) are both

H.

16. A process according to claim 13 or claim 14 wherein A is (CH₂) ₄ and R¹ and R² are H to give a compound having the formula

wherein R, R³ and R⁵ are as previously defined for formula (I).

17. A process as claimed in claim 13 or claim14 wherein R is H, R³ is CO₂R⁴ and R⁴ is H.

18. A process as claimed in claim 13 wherein R⁵ is methylene substituted by a group of the formula -NHCOCR¹²R¹³R¹⁴, and R¹² is

NH₂, R¹¹CONH- or R¹¹SO₂NH-, R¹³ is H and R¹⁴ is -(CH₂)₄NH₂.

7. A process as claimed in claim 1 wherein R⁵ is C₁-C₆ alkyl,

C₁-C₆ alkyl substituted by C₁ -C₆ alkoxy or C₁-C₆ alkyl substituted by phenyl.

19. A process acoording to claim 13 wherein said compound of formula (I) produced is-:

2-{1-[2 (S)-carboxy-3-(S-lysyla mino)propyl]cyclopentyl- carbonylami n o}-2,3-d ihydroi ndene-2-carboxylic acid,

2-{1-[2 (S)-carboxy-3-(N²-methanesulphonyl-S-lysyla m ino)- propyl]cyclcpentylcarbonyla mino}-2,3-dihydroindene-2-carboxylic acid, or

2-{1-[2(S)-carboxy-3-(N²-methanesulphonyl-S-lysylamino)- propyl]cyclcpentylcarbonylamino}-2-hydroxymethyl-2,3- dihydroindene; or a biolabile ester derivatives thereof.