Inhibitors of the renal outer medullary potassium channel

1. A compound having structural Formula I:

or a pharmaceutically acceptable salts thereof wherein:

Z 1 is

wherein the dashed line represents an optional double bond;

Z 2 is

R 1 is —H, —CH 3 , —CF 3 , —CHF 2 , —CH 2 F or —CH 2 OH;

R 2 is —H, oxo or —C 1-6 alkyl;

R 4 is —H, —OH, oxo, —F or —C 1-6 alkyl;

provided that when R 4 is —OH, oxo or —F, then R 2 is not oxo;

R 6 is —H, —OH, oxo, —F or —C 1-6 alkyl;

R 8 is —H, oxo or —C 1-6 alkyl;

provided that when R 6 is —OH, oxo or —F, then R 8 is not oxo;

R 3 , R 5 , R 7 , and R 9 are each independently —H or —C 1-6 alkyl;

provided that R 3 is absent when R 2 is oxo, R 5 is absent when R 4 is oxo, R 7 is absent when R 6 is oxo, and R 9 is absent when R 8 is oxo;

R 1a is —H, halo or —C 1-3 alkyl optionally substituted with one to three of —F;

one of R 1b and R 1c is —CN, —NO 2 or tetrazolyl, and the other is —H, halo, —O—C 1-3 alkyl, —COOC 1-3 alkyl or —C 1-3 alkyl optionally substituted with one to three of —F;

one of R 1d , R 1e and R 1f is —CN, —NO 2 or tetrazolyl, and each of the others is independently —H, halo, —O—C 1-3 alkyl, —COOC 1-3 alkyl or —C 1-3 alkyl optionally substituted with one to three of —F;

R 2a is —H, halo or —C 1-3 alkyl optionally substituted with one to three of —F;

one of R 2b and R 2c is —CN, —NO 2 or tetrazolyl, and the other is —H, halo, —O—C 1-3 alkyl, —COOC 1-3 alkyl or —C 1-3 alkyl optionally substituted with one to three of —F;

one of R 2d , R 2e and R 2f is —CN, —NO 2 or tetrazolyl, and each of the others is independently —H, halo, —O—C 1-3 alkyl, —COOC 1-3 alkyl or —C 1-3 alkyl optionally substituted with one to three of —F; and

R a and R b are each independently —H, halo, —O—C 1-3 alkyl, —COOC 1-3 alkyl or —C 1-3 alkyl optionally substituted with one to three of —F.

2. The compound of claim 1 or a pharmaceutically acceptable salt thereof having structural Formula II:

3. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein Z 1 is z1-a, z1-b, z1-d, z1-g or z1-h.

4. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein Z 1 is z1-c, z1-e or z1-f.

5. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein Z 1 is z1-a, z1-b, z1-d, z1-g or z1-h and Z 2 is z2-a or z2-b, and

(1) R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 and R 9 are each —H; or

(2) one or both of R 4 and R 6 are independently —OH, oxo or —F, and R 1 , R 2 , R 3 , R 5 , R 7 and R 8 are each —H.

6. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein Z 1 is z1-e or z1-f and R 2 is —H or oxo and R 3 is —H.

7. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein Z 1 is z1-a, z1-b, z1-d, z1-g or z1-h and Z 2 is z2-c, and

(1) R 2 , R 3 , R 4 and R 5 are each —H; or

(2) R 4 is —OH, oxo or —F, and R 2 , R 3 and R 5 are each —H.

8. The compound of claim 1 or a pharmaceutically acceptable salt thereof which is:

1,4-bis[2-(4-nitrophenyl)ethyl]piperazin-2-one;

6-(4-(4-nitrophenethyl)-3-oxopiperazin-1-yl)-5,6,7,8-tetrahydronaphthalene-2-carbonitrile;

6-{4-[2-(4-Nitrophenyl)ethyl]-2-oxopiperazin-1-yl}-5,6,7,8-tetrahydronaphthalene-2-carbonitrile;

6-{2-Oxo-4-[2-(1-oxo-1,3-dihydro-2-benzofuran-5-yl)ethyl]piperazin-1-yl}-5,6,7,8-tetrahydronaphthalene-2-carbonitrile;

2-{2-Oxo-4-[2-(1-oxo-1,3-dihydro-2-benzofuran-5-yl)ethyl]piperazin-1-yl}-2,3-dihydro-1H-indene-5-carbonitrile; or

6-{4-[(2R)-2-Hydroxy-2-(4-methyl-1-oxo-1,3-dihydro-2-benzofuran-5-yl)ethyl]-2-oxopiperazin-1-yl}-5,6,7,8-tetrahydronaphthalene-2-carbonitrile.

9. A pharmaceutical composition comprised of a compound of claim 1 and a pharmaceutically acceptable carrier.

10. The pharmaceutical composition of claim 9 further comprising one or more additional active agent selected from losartan, valsartan, candesartan, olmesartan, telmesartan, eprosartan, irbesartan, azilsartan, hydrochlorothiazide, amlodipine, alacepril, benazepril, captopril, ceronapril, cilazapril, delapril, enalapril, enalaprilat, fosinopril, imidapril, lisinopril, moveltipril, perindopril, quinapril, ramipril, spirapril, temocapril, trandolapril, amiloride, spironolactone, epleranone, triamterene or acetazolamide or a pharmaceutically acceptable salt thereof.

11. A method for causing diueresis, natriuresis or both, comprising administering a compound of claim 1 in a therapeutically effective amount to a patient in need thereof.

12. A method for the treatment of one or more disorders selected from hypertension, acute heart failure, chronic heart failure, and pulmonary arterial hypertension comprising administering a compound of claim 1 in a therapeutically effective amount as appropriate, to a patient in need thereof.