Inhibitors of the renal outer medullary potassium channel

1. A compound having structural Formula Ia:

or a pharmaceutically acceptable salt thereof wherein:

Z is

R 1 is

wherein *** indicates attachment to the carbonyl carbon and ** indicates attachment to the tetrazolyl ring in Formula Ia;

X is O, NH or S;

m is an integer selected from 1 or 2;

n is an integer selected from 1 or 2;

X 1 , X 2 and X 3 are each independently selected from C(R 7 ) or N, provided that at least one of X 1 , X 2 and X 3 must be N and at most two of X 1 , X 2 and X 3 are N;

R a is —CN;

R b is —H or —C 1-6 alkyl;

R 2 is —H, —F, —Cl, —C 1-6 alkyl, —C 3-6 cycloalkyl or —OC 1-6 alkyl;

R 3 is —H, —F, —Cl, —CN, —C 1-6 alkyl, —C 3-6 cycloalkyl or —OC 1-6 alkyl;

R 4 is —F, —Cl, —CN, —C 1-6 alkyl, —C 3-6 cycloalkyl, —OC 1-4 alkyl or N-tetrazolyl;

or R 3 and R 4 are joined together with the carbon atoms in the phenyl ring to which they are attached to form:

wherein R is —H or —C 1-4 alkyl;

R 5 is —H, —Cl, —F, —CN, —C 1-4 alkyl, —C 3-6 cycloalkyl or —OC 1-4 alkyl;

provided that when R 3 and R 4 are not joined together, then one and only one of R 3 , R 4 or R 5 is —CN;

R 6 is —H or —C 1-4 alkyl; and

R 7 is —H, —F, —Cl or —C 1-4 alkyl.

2. The compound of claim 1 having structural Formula I:

or a pharmaceutically acceptable salt thereof wherein:

X is O, NH or S;

R 1 is

wherein *** indicates attachment to the carbonyl carbon and ** indicates attachment to the tetrazolyl ring in Formula I;

m is an integer selected from 1 or 2;

n is an integer selected from 1 or 2;

X 1 , X 2 and X 3 are each independently selected from C(R 7 ) or N, provided that at least one of X 1 , X 2 and X 3 must be N and at most two of X 1 , X 2 and X 3 are N;

R 2 is —H, —F, —Cl, —C 1-6 alkyl, —C 3-6 cycloalkyl or —OC 1-6 alkyl;

R 3 is —H, —F, —Cl, —CN, —C 1-6 alkyl, —C 3-6 cycloalkyl or —OC 1-6 alkyl;

R 4 is —F, —Cl, —CN, —C 1-6 alkyl, —C 3-6 cycloalkyl, —OC 1-4 alkyl or N-tetrazolyl;

or R 3 and R 4 are joined together with the carbon atoms in the phenyl ring to which they are attached to form:

wherein R is —H or —C 1-4 alkyl;

R 5 is —H, —Cl, —F, —CN, —C 1-4 alkyl, —C 3-6 cycloalkyl or —OC 1-4 alkyl;

provided that when R 3 and R 4 are not joined together, then one and only one of R 3 , R 4 or R 5 is —CN;

R 6 is —H or —C 1-4 alkyl; and

R 7 is —H, —F, —Cl or —C 1-4 alkyl.

3. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein X is O.

4. The compound of claim 3 or a pharmaceutically acceptable salt thereof wherein m is 1 and R 6 is —H.

5. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 1 is:

6. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 2 is —H or —F; R 3 is —H, —F, —CN or —OCH 3 ; R 4 is —F, —CN or —OCH 3 ; and R 5 is —H, —Cl, —F, —CN, —CH 3 , —CH 2 CH 3 , cyclopropyl or —OCH 3 ; provided that one and only one of R 3 , R 4 or R 5 is —CN.

7. The compound of claim 1 or a pharmaceutically acceptable salt thereof wherein R 3 and R 4 are joined together with the carbon atoms in the phenyl ring to which they are attached to form:

and R is —H or —CH 3 .

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

X is O, NH or S;

R 1 is

wherein *** indicates attachment to the carbonyl carbon and ** indicates attachment to the tetrazolyl ring in Formula Ia;

m is an integer selected from 1 or 2;

n is an integer selected from 1 or 2;

X 1 , X 2 and X 3 are each independently selected from CH or N, provided that at least one of X 1 , X 2 and X 3 must be N and at most two of X 1 , X 2 and X 3 are N;

R a is —CN;

R b is —H or —C 1-3 alkyl;

R 2 is —H or —F;

R 3 is —H, —F, —CN or —OCH 3 ;

R 4 is —F, —CN or —OCH 3 ;

or R 3 and R 4 are joined together with the carbon atoms in the phenyl ring to which they are attached to form:

wherein R is —H or —CH 3 ;

R 5 is —H, —Cl, —F, —CN, —CH 3 , —CH 2 CH 3 , cyclopropyl or —OCH 3 ;

provided that when R 3 and R 4 are not joined together, then one and only one of R 3 , R 4 or R 5 is —CN; and further provided that when R 3 and R 4 are joined together, then R 5 is —H, —Cl, —F, —CH 3 or —CH 2 CH 3 ;

R 6 is —H or —C 1-4 alkyl; and

R 7 is —H, —F, —Cl or —C 1-4 alkyl.

9. The compound of claim 1 having structural Formula II:

or a pharmaceutically acceptable salt thereof wherein:

X is O or NH;

R 1 is:

R 3 is —F, R 4 is —CN and R 5 is —CH 3 ; or

R 3 and R 4 are joined together with the carbon atoms in the phenyl ring to which they are attached to form:

wherein R is —H or —CH 3 , and R 5 is —H.

10. The compound of claim 1 having structural Formula III:

or a pharmaceutically acceptable salt thereof.

11. The compound of claim 1 which is:

6-fluoro-2-methyl-3-[(3R,9aS)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]benzonitrile;

6-fluoro-2-methyl-3-[(3S,9aR)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]benzonitrile;

6-fluoro-2-methyl-3-[(3S,9aS)-8-{[3-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]benzonitrile;

6-fluoro-2-methyl-3-[(3S,9aR)-8-{[3-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]benzonitrile;

6-[(3R,9aS)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]-3,4-dihydro-1H-isochromen-1-one;

(3R)-3-methyl-6-[(3R,9aS)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]-3,4-dihydro-1H-isochromen-1-one;

(3S)-3-methyl-6-[(3R,9aS)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]-3,4-dihydro-1H-isochromen-1-one;

6-Fluoro-2-methyl-3-[(3S,9aR)-8-{[(5S)-2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[d]pyrimidin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]benzonitrile;

6-fluoro-2-methyl-3-[(3R,9aR)-8-{[3-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl]carbonyl}octahydro-2H-pyrazino[1,2-a]pyrazin-3-yl]benzonitrile;

6-fluoro-2-methyl-3-[(3S,9aR)-8-{[3-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl]carbonyl}octahydro-2H-pyrazino[1,2-a]pyrazin-3-yl]benzonitrile;

6-fluoro-2-methyl-3-[(3S,9aS)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[d]pyrimidin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]benzonitrile;

(3S)-3-methyl-6-[(3R,9aR)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]-3,4-dihydro-1H-isochromen-1-one;

or (3S)-3-methyl-6-[(3S,9aR)-8-{[2-(1H-tetrazol-1-yl)-6,7-dihydro-5H-cyclopenta[b]pyridin-5-yl]carbonyl}octahydropyrazino[2,1-c][1,4]oxazin-3-yl]-3,4-dihydro-1H-isochromen-1-one;

or a pharmaceutically acceptable salt thereof.

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

13. The pharmaceutical composition of claim 12 further comprising an active agent selected from losartan, valsartan, candesartan, olmesartan, telmesartan, eprosartan, irbesartan, amlodipine, alacepril, benazepril, captopril, ceronapril, cilazapril, delapril, enalapril, enalaprilat, fosinopril, imidapril, lisinopril, moveltipril, perindopril, quinapril, ramipril, spirapril, temocapril, or trandolapril, amiloride, spironolactone, epleranone or triamterene, or a pharmaceutically acceptable salt thereof.

14. 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.

15. A method for the treatment or prophylaxis of one or more disorders selected from hypertension, acute heart failure, chronic heart failure, pulmonary arterial hypertension, cardiovascular disease, diabetes, endothelial dysfunction, diastolic dysfunction, stable and unstable angina pectoris, thrombosis, myocardial infarction, stroke, cardiac insufficiency, pulmonary hypertonia, atherosclerosis, hepatic cirrhosis, ascitis, pre-eclampsia, cerebral edema, nephropathy, nephrotic syndrome, acute kidney insufficiency, chronic kidney disease, hypercalcemia, Dent's disease, Meniere's disease, or edematous states comprising administering a compound of claim 1 in a therapeutically or prophylactically effective amount as appropriate, to a patient in need thereof.