Endothelin receptor antagonists

Abstract

Novel furans and thiophenes, pharmaceutical compositions containing these compounds and their use as endothelin receptor antagonists are described.

Description

FIELD OF INVENTION

The present invention relates to furans and thiophenes, pharmaceutical compositions containing these compounds and their use as endothelin receptor antagonists.

Endothelin (ET) is a highly potent vasoconstrictor peptide synthesized and released by the vascular endothelium. Endothelin exists as three isoforms, ET- 1, ET-2 and ET-3. [Unless otherwise stated "endothelin" shall mean any or all of the isoforms of endothelin]. Endothelin has profound effects on the cardiovascular system, and in particular, the coronary, renal and cerebral circulation. Elevated or abnormal release of endothelin is associated with smooth muscle contraction which is involved in the pathogenesis of cardiovascular, cerebrovascular, respiratory and renal pathophysiology. Elevated levels of endothelin have been reported in plasma from patients with essential hypertension, acute myocardial infarction, subarachnoid hemorrhage, atherosclerosis, and patients with uraemia undergoing dialysis.

In vivo, endothelin has pronounced effects on blood pressure and cardiac output. An intravenous bolus injection of ET (0.1 to 3 nmol/kg) in rats causes a transient, dose-related depressor response (lasting 0.5 to 2 minutes) followed by a sustained, dose-dependent rise in arterial blood pressure which can remain elevated for 2 to 3 hours following dosing. Doses above 3 nmol/kg in a rat often prove fatal.

Endothelin appears to produce a preferential effect in the renal vascular bed. It produces a marked, long-lasting decrease in renal blood flow, accompanied by a significant decrease in GFR, urine volume, urinary sodium and potassium excretion. Endothelin produces a sustained antinatriuretic effect, despite significant elevations in atrial natriuretic peptide. Endothelin also stimulates plasma renin activity. These findings suggest that ET is involved in the regulation of renal function and is involved in a variety of renal disorders including acute renal failure, cyclosporine nephrotoxicity, radio contrast induced renal failure and chronic renal failure.

Studies have shown that in vivo, the cerebral vasculature is highly sensitive to both the vasodilator and vasoconstrictor effects of endothelin. Therefore, ET may be an important mediator of cerebral vasospasm, a frequent and often fatal consequence of subarachnoid hemorrhage.

ET also exhibits direct central nervous system effects such as severe apnea and ischemic lesions which suggests that ET may contribute to the development of cerebral infarcts and neuronal death.

ET has also been implicated in myocardial ischemia (Nichols et al. Br. J. Pharm. 99: 597-601, 1989 and Clozel and Clozel, Circ. Res., 65: 1193-1200, 1989) coronary vasospasm (Fukuda et al., Eur. J. Pharm. 165: 301-304, 1989 and Luscher, Circ. 83: 701, 1991) heart failure, proliferation of vascular smooth muscle cells, (Takagi, Biochem & Biophys. Res. Commun.; 168: 537-543, 1990, Bobek et al., Am. J. Physiol. 258:408-C415, 1990) and atherosclerosis, (Nakaki et al., Biochem. & Biophys. Res. Commun. 158: 880-881, 1989, and Lerman et al., New Eng. J. of Med. 325: 997-1001, 1991). Increased levels of endothelin have been shown after coronary balloon angioplasty (Kadel et al., No. 2491 Circ. 82: 627, 1990).

Further, endothelin has been found to be a potent constrictor of isolated mammalian airway tissue including human bronchus (Uchida et al., Eur J. of Pharm. 154: 227-228 1988, LaGente, Clin. Exp. Allergy 20: 343-348, 1990; and Springall et al., Lancet, 337: 697-701, 1991). Endothelin may play a role in the pathogenesis of interstitial pulmonary fibrosis and associated pulmonary hypertension, Glard et al., Third International Conference on Endothelin, 1993, p. 34 and ARDS (Adult Respiratory Distress Syndrome), Sanai et al., Supra, p. 112.

Endothelin has been associated with the induction of hemorrhagic and necrotic damage in the gastric mucosa (Whittle et al., Br. J. Pharm. 95: 1011-1013, 1988); Raynaud's phenomenon, Cinniniello et al., Lancet 337: 114-115, 1991); Crohn's Disease and ulcerative colitis, Munch et al., Lancet, Vol. 339, p. 381; Migraine (Edmeads, Headache, February 1991 p 127); Sepsis (Weitzberg et al., Circ. Shock 33: 222-227, 1991; Pittet et al., Ann. Surg. 213: 262-264, 1991), Cyclosporin-induced renal failure or hypertension (Eur. J. Pharmacol., 180: 191-192, 1990, Kidney Int, 37: 1487-1491, 1990) and endotoxin shock and other endotoxin induced diseases (Biochem. Biophys. Res. Commun., 161: 1220-1227, 1989, Acta Physiol. Scand. 137: 317-318, 1989) and inflammatory skin diseases. (Clin Res. 41:451 and 484, 1993).

Endothelin has also been implicated in preclampsia of pregnancy. Clark et al., Am. J. Obstet. Gynecol. March 1992, p. 962-968; Kamor et al., N. Eng. J. of Med., Nov. 22, 1990, p. 1486-1487; Dekker et al., Eur J. Ob. and Gyn. and Rep. Bio. 40 (1991) 215-220; Schiff et al., Am. J. Ostet. Gynecol. February 1992, p. 624-628; diabetes mellitus, Takahashi et al., Diabetologia (1990) 33:306-310; and acute vascular rejection following kidney transplant, Watschinger et al., Transplantation Vol. 52, No. 4, pp. 743-746.

Endothelin stimulates both bone resorption and anabolism and may have a role in the coupling of bone remodeling. Tatrai et al. Endocrinology, Vol. 131, p. 603-607.

Endothelin has been reported to stimulate the transport of sperm in the uterine cavity, Casey et al., J. Clin. Endo and Metabolism, Vol. 74, No. 1, p. 223-225, therefore endothelin antagonists may be useful as male contraceptives. Endothelin modulates the ovarian/menstrual cycle, Kenegsberg, J. of Clin. Endo. and Met., Vol. 74, No. 1, p. 12, and may also play a role in the regulation of penile vascular tone in man, Lau et al., Asia Pacific J. of Pharm., 1991, 6:287-292 and Tejada et al., J. Amer. Physio. Soc. 1991, H1078-H1085. Endothelin also mediates a potent contraction of human prostatic smooth muscle, Langenstroer et al., J. Urology, Vol. 149, p. 495-499.

Thus, endothelin receptor antagonists would offer a unique approach toward the pharmacotherapy of hypertension, renal failure, ischemia induced renal failure, sepsis-endotoxin induced renal failure, prophylaxis and/or treatment of radio-contrast induced renal failure, acute and chronic cyclosporin induced renal failure, cerebrovascular disease, myocardial ischemia, angina, heart failure, asthma, pulmonary hypertension, pulmonary hypertension secondary to intrinsic pulmonary disease, atherosclerosis, Raynaud's phenomenon, ulcers, sepsis, migraine, glaucoma, endotoxin shock, endotoxin induced multiple organ failure or disseminated intravascular coagulation, cyclosporin-induced renal failure and as an adjunct in angioplasty for prevention of restenosis, diabetes, preclampsia of pregnancy, bone remodeling, kidney transplant, male contraceptives, infertility and priaprism and benign prostatic hypertrophy.

SUMMARY OF THE INVENTION

This invention comprises compounds represented by Formula (I) and pharmaceutical compositions containing these compounds, and their use as endothelin receptor antagonists which are useful in the treatment of a variety of cardiovascular and renal diseases including but not limited to: hypertension, acute and chronic renal failure, cyclosporine induced nephrotoxicity, benign prostatic hypertrophy, pulmonary hypertension, migraine, stroke, cerebrovascular vasospasm, myocardial ischemia, angina, heart failure, atherosclerosis, and as an adjunct in angioplasty for prevention of restenosis.

This invention further constitutes a method for antagonizing endothelin receptors in an animal, including humans, which comprises administering to an animal in need thereof an effective amount of a compound of Formula (I).

DETAILED DESCRIPTION OF THE INVENTION

The compounds of this invention are represented by structural Formula (I): ##STR1## D is O or S; P is tetrazol-5-yl, CO.sub.2 R.sub.6 or C(O)N(R.sub.6)S(O).sub.q R.sub.10 ;

R.sup.a is hydrogen or C.sub.1-6 alkyl; R.sub.1 is independently hydrogen, Ar or C.sub.1-6 alkyl; R.sub.2 is Ar, C.sub.1-8 alkyl, C(O)R.sub.14 or ##STR2## R.sub.3 and R.sub.5 are independently R.sub.13 OH, C.sub.1-8 alkoxy, S(O).sub.q R.sub.11, N(R.sub.6).sub.2, Br, F, I, Cl, CF.sub.3, NHCOR.sub.6 R.sub.13 CO.sub.2 R.sub.7, --X--R.sub.9 --Y or --X(CH.sub.2).sub.n R.sub.8 wherein each methylene group within --X(CH.sub.2).sub.n R.sub.8 may be unsubstituted or substituted by one or two --(CH.sub.2).sub.n Ar groups; R.sub.4 is independently R.sub.11, OH, C.sub.1-5 alkoxy, S(O).sub.q R.sub.11, N(R.sub.6).sub.2, Br, F, I, Cl or NHCOR.sub.6, wherein the C.sub.1-5 alkoxy may be unsubstituted or substituted by OH, methoxy or halogen; R.sub.6 is independently hydrogen or C.sub.1-8 alkyl; R.sub.7 is independently hydrogen, C.sub.1-10 alkyl, C.sub.2-10 alkenyl or C.sub.2-8 alkynyl, all of which may be unsubstituted or substituted by one or more OH, N(R.sub.6).sub.2, CO.sub.2 R.sub.12, halogen or XC.sub.1-10 alkyl; or R.sub.7 is (CH.sub.2).sub.n Ar; R.sub.8 is independently R.sub.11, CO.sub.2 R.sub.7, CO.sub.2 C(R.sub.11).sub.2 O(CO)XR.sub.7, PO.sub.3 (R.sub.7).sub.2, SO.sub.2 NR.sub.7 R.sub.11, NR.sub.7 SO.sub.2 R.sub.11, CONR.sub.7 SO.sub.2 R.sub.11, SO.sub.3 R.sub.7, SO.sub.2 R.sub.7, P(O)(OR.sub.7)R.sub.7, CN, CO.sub.2 (CH.sub.2).sub.m C(O)N(R.sub.6).sub.2, C(R.sub.11).sub.2 N(R.sub.7).sub.2, C(O)N(R.sub.6).sub.2, NR.sub.7 C(O)NR.sub.7 SO.sub.2 R.sub.11 tetrazole or OR.sub.6 ; R.sub.9 is independently a bond, C.sub.1-10 alkylene, C.sub.1-10 alkenylene, C.sub.1-10 alkylidene, C.sub.1-10 alkynylene, all of which may be linear or branched, or phenylene, all of which may be unsubstituted or substituted by one of more OH, N(R.sub.6).sub.2, COOH or halogen; R.sub.10 is independently C.sub.1-10 alkyl, N(R.sub.6).sub.2 or Ar; R.sub.11 is independently hydrogen, Ar, C.sub.1-8 alkyl, C.sub.2-8 alkenyl, C.sub.2-8 alkynyl, all of which may be unsubstituted or substituted by one or more OH, CH.sub.2 OH, N(R.sub.6).sub.2 or halogen; R.sub.12 is independently hydrogen, C.sub.1-6 alkyl, C.sub.2-6 alkenyl or C.sub.2-7 alkynyl; R.sub.13 is independently divalent Ar, C.sub.1-10 alkylene, C.sub.1-10 alkylidene, C.sub.2-10 alkenylene, all of which may be unsubstituted or substituted by one or more OH, CH.sub.2 OH, N(R.sub.6).sub.2 or halogen; R.sub.14 is independently hydrogen, C.sub.1-10 alkyl, XC.sub.1-10 alkyl, Ar or XAr; R.sub.15 is independently C.sub.1-6 alkyl or phenyl substituted by one or two C.sub.1-6 alkyl, OH, C.sub.1-5 alkoxy, S(O).sub.q R.sub.6, N(R.sub.6).sub.2, Br, F, I, Cl, CF.sub.3 or NHCOR.sub.6 ; X is independently (CH.sub.2).sub.n, O, NR.sub.6 or S(O).sub.q ; Y is independently CH.sub.3 or X(CH.sub.2).sub.n Ar; Ar is independently: ##STR3## naphthyl, furyl, oxozolyl, indolyl, pyridyl, thienyl, oxazolidinyl, thiazolyl, isothiazolyl, pyrazolyl, triazolyl, tetrazolyl, imidazolyl, imidazolidinyl, thiazolidinyl, isoxazolyl, oxadiazolyl, thiadiazolyl, morpholinyl, piperidinyl, piperazinyl, pyrrolyl, or pyrimidyl; all of which may be unsubstituted or substituted by one or more Z.sub.1 or Z.sub.2 groups; A is independently C.dbd.O, or (C(R.sub.6).sub.2).sub.m ; B is independently --CH.sub.2 -- or --O--; Z.sub.1 and Z.sub.2 are independently hydrogen, XR.sub.6, C.sub.1-8 alkyl, (CH.sub.2).sub.q CO.sub.2 R.sub.6, C(O)N(R.sub.6).sub.2, CN, (CH2).sub.n OH, NO.sub.2, F, Cl, Br, I, N(R.sub.6).sub.2, NHC(O)R.sub.6, X(CH.sub.2).sub.n R.sub.8, O(CH.sub.2).sub.m C(O)NR.sub.a SO.sub.2 R.sub.15, (CH.sub.2).sub.m OC(O)NR.sub.a SO.sub.2 R.sub.15, O(CH.sub.2).sub.m NR.sub.a C(O)NR.sub.a SO.sub.2 R.sub.15, or tetrazolyl which may be substituted or unsubstituted by C.sub.1-6 alkyl, CF.sub.3 or C(O)R.sub.6 ; Ar' is naphthyl, furyl, oxozolyl, indolyl, pyridyl, thienyl, oxazolidinyl, thiazolyl, isothiazolyl, pyrazolyl, triazolyl, tetrazolyl, imidazolyl, imidazolidinyl, thiazolidinyl, isoxazolyl, oxadiazolyl, thiadiazolyl, morpholinyl, piperidinyl, piperazinyl, pyrrolyl, or pyrimidyl; all of which may be unsubstituted or substituted by one or more XR.sub.9 --Y, Z.sub.1 or Z.sub.2 groups; m is independently 1 to 3; n is independently 0 to 6; q is independently 0, 1 or 2; provided n is 1-6 in Formula (I) when R.sub.2 is furyl; and further provided that R.sub.3, R.sub.4 and R.sub.5 are not O--O(CH.sub.2).sub.n Ar; or a pharmaceutically acceptable salt thereof.

All alkyl, alkenyl, alkynyl and alkoxy groups may be straight or branched.

The compounds of the present invention may contain one or more asymmetric carbon atoms and may exist in racemic and optically active form. All of these compounds and diastereoisomers are contemplated to be within the scope of the present invention.

The preferred compounds are:

E-3-[4-n-Butyl-3-[(7-carboxy-4-methoxy)naphthyl]thien-2-yl]-2-[(2-methoxy-4,5-methylenedioxyphenyl)methyl]-2-propenoic acid E-3-[4-n-Butyl-3-[4-(2-carboxyphenyl)methoxy-2-methoxypyrimidyl]thien-2-yl]-2-[(2-methoxy-4,5-methylenedioxyphenyl)methyl]-2-propenoic acid E-3-[2-n-Butyl-3-[(7-carboxy-4-methoxy)naphthyl]fur-4-yl]-2-[(2-methoxy-4,5-methylenedioxyphenyl)methyl]-2-propenoic acid E-3-[2-n-Butyl-3-[4-(2-carboxyphenyl)methoxy-2-methoxypyrimidyl]fur-4-yl]-2-[(2-methoxy-4,5-methylenedioxyphenyl)methyl]-2-propenoic acid

The present invention provides compounds of Formula (I). ##STR4## which can be prepared by a process comprising: treating an aryl halide of Formula (2)

Ar'--X (2) with an appropriate alkyllithium reagent such as n-butyllithium in tetrahydrofuran followed by addition of a borate such as triisopropyl borate and acidic work up affords a boronic acid of Formula (3). Ar'--B(OH).sub.2 (3) Reaction of boronic acid of Formula (3) with a compound of Formula (4) ##STR5## in the presence of a suitable base such as potassium carbonate with a palladium catalyst such as tetrakis(triphenylphosphine)palladium(O) in a mixture of toluene, ethanol and water at approximately 80-100.degree. C. provides a compound of Formula (5) ##STR6## A compound of Formula (4) may be prepared from a dibromide of Formula (6) by ##STR7## monohalogen-metal exchage using an appropriate alkyllithium reagent such as n-butyllithium in tetrahydrofuran followed by addition of an alkylating agent (eg. N,N-dimethylformate or R.sup.a COCl). Knoevenagel condensation of an aldehyde of Formula (5) with a half acid of Formula (7) ##STR8## in a solvent such as benzene at reflux, in the presence of piperidium acetate with azeotropic removal of water using a Dean-Stark apparatus, affords an ester of Formula (8). ##STR9## Saponification of an ester of Formula (8) using aqueous sodium hydroxide in a solvent such as ethanol provides, after acidification with aqueous hydrochloric acid, an acid of Formula (1), wherein P.dbd.COOH.

In order to use a compound of the Formula (I) or a pharmaceutically acceptable salt thereof for the treatment of humans and other mammals it is normally formulated in accordance with standard pharmaceutical practice as a pharmaceutical composition.

Compounds of Formula (I) and their pharmaceutically acceptable salts may be administered in a standard manner for the treatment of the indicated diseases, for example orally, parenterally, sub-lingually, transdermally, rectally, via inhalation or via buccal administration.

Compounds of Formula (I) and their pharmaceutically acceptable salts which are active when given orally can be formulated as syrups, tablets, capsules and lozenges. A syrup formulation will generally consist of a suspension or solution of the compound or salt in a liquid carrier for example, ethanol, peanut oil, olive oil, glycerine or water with a flavouring or colouring agent. Where the composition is in the form of a tablet, any pharmaceutical carrier routinely used for preparing solid formulations may be used. Examples of such carriers include magnesium stearate, terra alba, talc, gelatin, agar, pectin, acacia, stearic acid, starch, lactose and sucrose. Where the composition is in the form of a capsule, any routine encapsulation is suitable, for example using the aforementioned carriers in a hard gelatin capsule shell. Where the composition is in the form of a soft gelatin shell capsule any pharmaceutical carrier routinely used for preparing dispersions or suspensions may be considered, for example aqueous gums, celluloses, silicates or oils and are incorporated in a soft gelatin capsule shell.

Typical parenteral compositions consist of a solution or suspension of the compound or salt in a sterile aqueous or non-aqueous carrier optionally containing a parenterally acceptable oil, for example polyethylene glycol, polyvinylpyrrolidone, lecithin, arachis oil, or sesame oil.

Typical compositions for inhalation are in the form of a solution, suspension or emulsion that may be administered as a dry powder or in the form of an aerosol using a conventional propellant such as dichlorodifluoromethane or trichlorofluoromethane.

A typical suppository formulation comprises a compound of Formula (1) or a pharmaceutically acceptable salt thereof which is active when administered in this way, with a binding and/or lubricating agent, for example polymeric glycols, gelatins, cocoa-butter or other low melting vegetable waxes or fats or their synthetic analogues.

Typical transdermal formulations comprise a conventional aqueous or non-aqueous vehicle, for example a cream, ointment, lotion or paste or are in the form of a medicated plaster, patch or membrane.

Preferably the composition is in unit dosage form, for example a tablet, capsule or metered aerosol dose, so that the patient may administer to themselves a single dose.

Each dosage unit for oral administration contains suitably from 0.1 mg to 500 mg/Kg, and preferably from 1 mg to 100 mg/Kg, and each dosage unit for parenteral administration contains suitably from 0.1 mg to 100 mg, of a compound of Formula (I) or a pharmaceutically acceptable salt thereof calculated as the free acid. Each dosage unit for intranasal administration contains suitably 1-400 mg and preferably 10 to 200 mg per person. A topical formulation contains suitably 0.01 to 1.0% of a compound of Formula (I).

The daily dosage regimen for oral administration is suitably about 0.01 mg/Kg to 40 mg/Kg, of a compound of Formula (I) or a pharmaceutically acceptable salt thereof calculated as the free acid. The daily dosage regimen for parenteral administration is suitably about 0.001 mg/Kg to 40 mg/Kg, of a compound of the Formula (I) or a pharmaceutically acceptable salt thereof calculated as the free acid. The daily dosage regimen for intranasal administration and oral inhalation is suitably about 10 to about 500 mg/person. The active ingredient may be administered from 1 to 6 times a day, sufficient to exhibit the desired activity.

No unacceptable toxicological effects are expected when compounds of the invention are administered in accordance with the present invention.

The biological activity of the compounds of Formula (I) are demonstrated by the following tests:

I. Binding Assay

A) CHO cell membrane preparation

CHO cells stably transfected with human ET.sub.A and ET.sub.B receptors were grown in 245 mm.times.245 mm tissue culture plates in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum. The confluent cells were washed with Dulbecco's phosphate-buffered saline containing a protease inhibitor cocktail (5 mM EDTA, 0.5 mM PMSF, 5 ug/ml of leupeptin and 0.1 U/ml of aprotinin) and scraped in the same buffer. After centrifugation at 800.times.g, the cells were lysed by freezing in liquid nitrogen and thawing on ice followed by homogenization (30 times using a glass dounce homogenizer) in lysis buffer containing 20 mM Tris HCl, pH 7.5, and the protease inhibitor cocktail. After an initial centrifugation at 800.times.g for 10 min to remove unbroken cells and nuclei, the supernatants were centrifuged at 40,000.times.g for 15 min and the pellet was resuspended in 50 mM Tris HCI, pH 7.5, and 10 mM MgCl.sub.2 and stored in small aliquots at -70.degree. C. after freezing in liquid N.sub.2. Protein was determined by using the BCA method and BSA as the standard.

(B) Binding studies

[.sup.125 I]ET-1 binding to membranes prepared from CHO cells was performed following the procedure of Elshourbagy et al. (1993). Briefly, the assay was initiated in a 100 ul volume by adding 25 ul of [.sup.125 I]ET-1 (0.2-0.3 nM) in 0.05% BSA to membranes in the absence (total binding) or presence (nonspecific binding) of 100 nM unlabeled ET-1. The concentrations of membrane proteins were 0.5 and 0.05 ug per assay tube for ET.sub.A and ET.sub.B receptors, respectively. The incubations (30.degree. C., 60 min) were stopped by dilution with cold buffer (20 mM Tris HCI, pH 7.6, and 10 mM MgCl.sub.2) and filtering through Whatman GF/C filters (Clifton, N.J.) presoaked in 0.1% BSA. The filters were washed 3 times (5 ml each time) with the same buffer by using a Brandel cell harvester and were counted by using a gamma counter at 75% efficiency.

The following example is illustrative and are not limiting of the compounds of this invention.

EXAMPLE 1

Formulations for pharmaceutical use incorporating compounds of the present invention can be prepared in various forms and with numerous excipients. Examples of such formulations are given below.

Inhalant Formulation

A compound of Formula I, (1 mg to 100 mg) is aerosolized from a metered dose inhaler to deliver the desired amount of drug per use.

______________________________________Tablets/Ingredients Per Tablet______________________________________1. Active ingredient 40 mg (Cpd of Form. I)2. Corn Starch 20 mg3. Alginic acid 20 mg4. Sodium Alginate 20 mg5. Mg stearate 1.3 mg 2.3 mg______________________________________ Procedure for tablets Step 1 Blend ingredients No. 1, No. 2, No. 3 and No. 4 in a suitable mixer/blender. Step 2 Add sufficient water portion-wise to the blend from Step 1 with careful mixing after each addition. Such additions of water and mixing until the mass is of a consistency to permit its conversion to wet granules. Step 3 The wet mass is converted to granules by passing it through an oscillating granulator using a No. 8 mesh (2.38 mm) screen. Step 4 The wet granules are then dried in an oven at 140.degree. F. (60.degree. C.) until dry. Step 5 The dry granules are lubricated with ingredient No. 5. Step 6 The lubricated granules are compressed on a suitable tablet press. Parenteral Formulation

A pharmaceutical composition for parenteral administration is prepared by dissolving an appropriate amount of a compound of formula I in polyethylene glycol with heating. This solution is then diluted with water for injections Ph Eur. (to 100 ml). The solution is then steriled by filtration through a 0.22 micron membrane filter and sealed in sterile containers.

Claims

1. A compound of Formula (I): ##STR10## D is S; P is CO.sub.2 R.sub.6 or C(O)N(R.sub.6)S(O).sub.q R.sub.10 ;

R.sup.a is hydrogen or C.sub.1-6 alkyl;

R.sub.1 is independently hydrogen, Ar or C.sub.1-6 alkyl;

R.sub.2 is Ar, C.sub.1-8 alkyl, C(O)R.sub.14 or ##STR11## R.sub.3 and R.sub.5 are independently R.sub.13 OH, C.sub.1-8 alkoxy, S(O).sub.q R.sub.11, N(R.sub.6).sub.2, Br, F, I, Cl, CF.sub.3, NHCOR.sub.6 R.sub.13 CO.sub.2 R.sub.7, --X--R.sub.9 --Y or --X(CH.sub.2).sub.n R.sub.8 wherein each methylene group within --X(CH.sub.2).sub.n R.sub.8 may be unsubstituted or substituted by one or two --(CH.sub.2).sub.n Ar groups;

R.sub.4 is independently R.sub.11, OH, C.sub.1-5 alkoxy, S(O).sub.q R.sub.11, N(R.sub.6).sub.2, Br, F, I, Cl or NHCOR.sub.6, wherein the C.sub.1-5 alkoxy may be unsubstituted or substituted by OH, methoxy or halogen;

R.sub.6 is independently hydrogen or C.sub.1-8 alkyl;

R.sub.7 is independently hydrogen, C.sub.1-10 alkyl, C.sub.2-10 alkenyl or C.sub.2-8 alkynyl, all of which may be unsubstituted or substituted by one or more OH, N(R.sub.6).sub.2, CO.sub.2 R.sub.12, halogen or XC.sub.1-10 alkyl; or R.sub.7 is (CH.sub.2).sub.n Ar;

R.sub.8 is independently R.sub.11, CO.sub.2 R.sub.7, CO.sub.2 C(R.sub.11).sub.2 O(CO)XR.sub.7, PO.sub.3 (R.sub.7).sub.2, SO.sub.2 NR.sub.7 R.sub.11, NR.sub.7 SO.sub.2 R.sub.11, CONR.sub.7 SO.sub.2 R.sub.11, SO.sub.3 R.sub.7, SO.sub.2 R.sub.7, P(O)(OR.sub.7)R.sub.7, CN, CO.sub.2 (CH.sub.2).sub.m C(O)N(R.sub.6).sub.2, C(R.sub.11).sub.2 N(R.sub.7).sub.2, C(O)N(R.sub.6).sub.2, NR.sub.7 C(O)NR.sub.7 SO.sub.2 R.sub.11, or OR.sub.6 ;

R.sub.9 is independently a bond, C.sub.1-10 alkylene, C.sub.1-10 alkenylene, C.sub.1-10 alkylidene, C.sub.1-10 alkynylene, all of which may be linear or branched, or phenylene, all of which may be unsubstituted or substituted by one of more OH, N(R.sub.6).sub.2, COOH or halogen;

R.sub.10 is independently C.sub.1-10 alkyl, N(R.sub.6).sub.2 or Ar;

R.sub.11 is independently hydrogen, Ar, C.sub.1-8 alkyl, C.sub.2-8 alkenyl, C.sub.2-8 alkynyl, all of which may be unsubstituted or substituted by one or more OH, CH.sub.2 OH, N(R.sub.6).sub.2 or halogen;

R.sub.12 is independently hydrogen, C.sub.1-6 alkyl, C.sub.2-6 alkenyl or C.sub.2-7 alkynyl;

R.sub.13 is independently divalent Ar, C.sub.1-10 alkylene, C.sub.1-10 alkylidene, C.sub.2-10 alkenylene, all of which may be unsubstituted or substituted by one or more OH, CH.sub.2 OH, N(R.sub.6).sub.2 or halogen;

R.sub.14 is independently hydrogen, C.sub.1-10 alkyl, XC.sub.1-10 alkyl, Ar or XAr;

R.sub.15 is independently C.sub.1-6 alkyl or phenyl substituted by one or two C.sub.1-6 alkyl, OH, C.sub.1-5 alkoxy, S(O).sub.q R.sub.6, N(R.sub.6).sub.2, Br, F, I, Cl, CF.sub.3 or NHCOR.sub.6 ;

X is independently (CH.sub.2).sub.n, O, NR.sub.6 or S(O).sub.q ;

Y is independently CH.sub.3 or X(CH.sub.2).sub.n Ar;

Ar is independently:

Ar is independently: ##STR12## naphthyl, furyl, thienyl; all of which may be unsubstituted or substituted by one or more Z.sub.1 or Z.sub.2 groups;

A is independently C.dbd.O, or (C(R.sub.6).sub.2).sub.m ;

B is independently --CH.sub.2 -- or --O--;

Z.sub.1 and Z.sub.2 are independently hydrogen, XR.sub.6, C.sub.1-8 alkyl, (CH.sub.2).sub.q CO.sub.2 R.sub.6, C(O)N(R.sub.6).sub.2, CN, (CH.sub.2).sub.n OH, NO.sub.2, F, Cl, Br, I, N(R.sub.6).sub.2, NHC(O)R.sub.6, X(CH.sub.2).sub.n R.sub.8, O(CH.sub.2).sub.m C(O)NR.sub.a SO.sub.2 R.sub.15, (CH.sub.2).sub.m OC(O)NR.sub.a SO.sub.2 R.sub.15, or O(CH.sub.2).sub.m NR.sub.a C(O)NR.sub.a SO.sub.2 R.sub.15, or which may be substituted or unsubstituted by C.sub.1-6 alkyl, CF.sub.3 or C(O)R.sub.6 ;

Ar' is naphthyl, furyl, thienyl; all of which may be unsubstituted or substituted by one or more XR.sub.9 --Y, Z.sub.1 or Z.sub.2 groups;

m is independently 1 to 3;

n is independently 0 to 6;

q is independently 0, 1 or 2;

provided n is 1-6 in Formula (I) when R.sub.2 is furyl; and further provided that R.sub.3, R.sub.4 and R.sub.5 are not O--O(CH.sub.2).sub.n Ar;

or a pharmaceutically acceptable salt thereof.

2. A compound of claim 1 chosen from the group consisting of:

E-3-[4-n-Butyl-3-[(7-carboxy-4-methoxy)naphthyl]thien-2-yl]-2-[(2-methoxy-4,5-methylenedioxyphenyl)methyl]-2-propenoic acid.

3. A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier.

4. A method of treatment of diseases caused by an excess of endothelin comprising administering to a subject in need thereof, an effective amount of an endothelin receptor antagonist of claim 1.

5. A method of treating renal failure, hypertension, pulmonary hypertension or heart failure which comprises administering to a subject in need thereof, an effective amount of a compound of claim 1.