Substituted bicyclic heteroaryl allosteric modulators of nicotinic acetylcholine receptors

1. A compound having the formula I:

or a pharmaceutically acceptable salt thereof, wherein:

X is selected from

Y is 4 substituents, each independently selected from H, (C 1 -C 4 )alkyl, halogen, and OH, wherein said alkyl is optionally substituted with one or more halogen or OH;

A is a bicyclic heteroaryl ring which is substituted with 0 to 4 R groups each independently selected from OH, oxo, amino, amido, carboxyl, keto, CN, alkoxy, S(O) m -alkyl, halogen, aminoalkyl, hydroxyalkyl, alkyl, cycloalkyl, alkynyl, aryl, heteroaryl, and heterocyclyl, wherein said amino, amido, carboxyl, keto, alkoxy, S(O) m -alkyl, aminoalkyl, hydroxyalkyl, alkyl, cycloalkyl, alkynyl, aryl, heteroaryl and heterocyclyl are optionally substituted with one or more substituents independently selected from F, Cl, Br, OH, oxo, CF 3 , OCF 3 , CN, (C 1 -C 6 )alkyl, O(C 1 -C 4 )alkyl, S(O) m —(C 1 -C 4 )alkyl, C═O(C 1 -C 4 )alkyl, (C═O)NR 7 R 8 , (C═O)OR 7 , (C 2 -C 4 )alkynyl, (C 3 -C 6 )cycloalkyl, O(C 3 -C 6 )cycloalkyl, C═O(C 3 -C 6 )cycloalkyl, aryl, heteroaryl and heterocyclyl, wherein said alkyl, aryl, heteroaryl and heterocyclyl are optionally independently substituted with one or more halogen, CF 3 , OH and oxo;

R 1 is H or (C 1 -C 4 )alkyl;

R 2 is H or (C 1 -C 4 )alkyl;

R 3 is H, halogen or (C 1 -C 4 )alkyl, wherein said alkyl is optionally substituted with one or more halogen;

R 4 is H, halogen or (C 1 -C 4 )alkyl, wherein said alkyl is optionally substituted with one or more halogen;

or, R 3 and R 4 optionally can come to together to form a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl ring wherein said ring may be optionally substituted with one or more substituents independently selected from OH, halogen, or (C 1 -C 4 )alkyl;

R 5 is H or (C 1 -C 4 )alkyl;

R 6 is H or (C 1 -C 4 )alkyl;

R 7 is H or (C 1 -C 4 )alkyl, wherein said alkyl is optionally substituted with one or more halogen;

R 8 is H or (C 1 -C 4 )alkyl, wherein said alkyl is optionally substituted with one or more halogen;

R a is H or (C 1 -C 4 )alkyl;

R b is H or (C 1 -C 4 )alkyl; and

m is 0, 1, or 2.

2. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein X is

3. The compound according to claim 2 , or a pharmaceutically acceptable salt thereof, wherein Y is H.

4. The compound of according to claim 3 , or a pharmaceutically acceptable salt thereof, wherein A is selected from benzoxazolyl, quinazolinyl, tetrahydrobenzoxazolyl, oxazolopyridinyl, quinoxalinyl, imidazopyridazinyl, benzothiazolyl, dihydrocyclopentaoxazolyl, naphthyridinyl, pyrazolopyridinyl, cinnolinyl, isoquinolyl, thienopyridinyl, indazolyl, tetrahydropyrazolopyridinyl, furopyridinyl, dihydropyridooxazinyl, tetrahydrobenzothiazolyl, tetrahydroquinazolinyl, benzoxazinyl, benzimidazolyl, thiazolopyridinyl, quinolinyl, pyridopyrimidinyl, phthalazinyl, pyridopyrazinyl, thienoxazole, and thienothiazole each optionally substituted with 1 to 2 R groups independently selected from halogen, CN, (C 1 -C 6 )alkyl, O(C 1 -C 6 )alkyl, NR 7 R 8 , (C 3 -C 6 )cycloalkyl, aryl, heteroaryl and heterocyclyl, wherein said alkyl, NR 7 R 8 , (C 3 -C 6 )cycloalkyl, aryl, heteroaryl and heterocyclyl are each optionally substituted with one or more substituents independently selected from halogen, CN, (C 1 -C 6 )alkyl, (C═O)O(C 1 -C 4 )alkyl, and phenyl.

5. The compound according to claim 4 , or a pharmaceutically acceptable salt thereof, wherein R 5 , R 6 , R a and R b are independently H or methyl.

6. The compound according to claim 5 , or a pharmaceutically acceptable salt thereof, wherein R 3 and R 4 are independently H, F or methyl.

7. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, having the formula:

or a pharmaceutically acceptable salt thereof, wherein;

A is selected from benzoxazolyl, quinazolinyl, tetrahydrobenzoxazolyl, oxazolopyridinyl, quinoxalinyl, imidazopyridazinyl, benzothiazolyl, dihydrocyclopentaoxazolyl, naphthyridinyl, pyrazolopyridinyl, cinnolinyl, isoquinolyl, thienopyridinyl, indazolyl, tetrahydropyrazolopyridinyl, furopyridinyl and dihydropyridooxazinyl, each optionally substituted with 1 to 2 R groups independently selected from F, Cl, (C 1 -C 4 )alkyl, O(C 1 -C 4 )alkyl and CF 3 ;

R 3 is H, F or methyl; and

R 4 is H, F or methyl.

8. The compound of claim 1 which is selected from the group consisting of

4-[(1R,3R)-3-(1,3-Benzoxazol-2-yl)-2,2-dimethylcyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(6-Fluoro-1,3-benzoxazol-2-yl)-2,2-dimethylcyclopropyl]benzenesulfonamide;

4-[(1R,2R)-2-(Quinazolin-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1R,2R)-2-(4,5,6,7-Tetrahydro-1,3-benzoxazol-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1R,2R)-2-(1,3-Benzoxazol-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-2,2-Dimethyl-3-([1,3]oxazolo[5,4-b]pyridin-2-yl)cyclopropyl]benzenesulfonamide;

4-[trans-2-(Quinoxalin-2-yl)cyclopropyl]benzenesulfonamide;

4-((1R,3R)-3-(Imidazo[1,2-b]pyridazin-2-yl)-2,2-dimethylcyclopropyl)benzenesulfonamide;

4-((1S,3S)-3-(Benzo[d]thiazol-2-yl)-2,2-dimethylcyclopropyl)benzenesulfonamide;

4-((1S,3S)-3-(6-Fluorobenzo[d]thiazol-2-yl)-2,2-dimethylcyclopropyl)benzenesulfonamide;

4-[(1R,3R)-3-(5,6-Dihydro-4H-cyclopenta[d][1,3]oxazol-2-yl)-2,2-dimethylcyclopropyl] benzenesulfonamide;

4-[(1R,3R)-2,2-Dimethyl-3-(5,6,7,8-tetrahydroquinazolin-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(4,4-Dimethyl-4H-3,1-benzoxazin-2-yl)-2,2-difluorocyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(4-Methoxy-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1R,2R)-2-(6-Fluoro-1,3-benzoxazol-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(4,6-Difluoro-1,3-benzothiazol-2-yl)-2,2-dimethyl-cyclopropyl] benzenesulfonamide;

4-[(1S,3S)-3-(1,3-Benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(6-Chloro-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(5-Chloro-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(1,3-Benzoxazol-2-yl)-2,2-difluoro-cyclopropyl]benzenesulfonamide;

4-[(1R,3S)-3-(1,3-Benzothiazol-2-yl)-2,2-difluoro-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(1H-Benzimidazol-2-yl)-2,2-difluorocyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(4,6-Difluoro-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(6-Fluoro-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(1,3-Benzothiazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1S,2S)-2-(1,3-Benzoxazol-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(6-Chloro-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(5-Chloro-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1S,2S)-2-(6-Fluoro-1,3-benzoxazol-2-yl)cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(4,6-Difluoro-1,3-benzothiazol-2-yl)-2,2-dimethyl-cyclopropyl] benzenesulfonamide;

4-[(1R,3R)-3-(6-Fluoro-1,3-benzothiazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-3-(5-Methoxy-1,3-benzoxazol-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(1,3-Benzoxazol-2-yl)-2,2-difluoro-cyclopropyl]benzenesulfonamide;

4-[(1S,3R)-3-(1,3-Benzothiazol-2-yl)-2,2-difluoro-cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-2,2-Dimethyl-3-quinazolin-2-yl-cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-3-(5-Fluoroquinazolin-2-yl)-2,2-dimethyl-cyclopropyl]benzenesulfonamide;

4-[(1S,3S)-2,2-Dimethyl-3-(4,5,6,7-tetrahydro-1,3-benzoxazol-2-yl)cyclopropyl] benzenesulfonamide;

4-[(1R,3R)-2,2-Difluoro-3-(4,5,6,7-tetrahydro-1,3-benzoxazol-2-yl)cyclopropyl] benzenesulfonamide;

4-[(1R,3R)-2,2-Dimethyl-3-quinazolin-2-yl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-2,2-Dimethyl-3-oxazolo[5,4-c]pyridin-2-yl-cyclopropyl]benzenesulfonamide;

4-[(1R,3R)-2,2-Dimethyl-3-(4,5,6,7-tetrahydro-1,3-benzoxazol-2-yl)cyclopropyl] benzenesulfonamide;

4-[(1R,3R)-3-(5,7-Difluoro-1-methyl-benzimidazol-2-yl)-2,2-dimethyl-cyclopropyl] benzenesulfonamide;

4-[(1S,3S)-3-(4,4-Dimethyl-4H-3,1-benzoxazin-2-yl)-2,2-difluorocyclopropyl]benzenesulfonamide;

4-[2-(2-Methyl-1,3-benzothiazol-4-yl)cyclopropyl]benzenesulfonamide;

4-[2-(7-Chloro-1,5-naphthyridin-3-yl)cyclopropyl]benzenesulfonamide;

4-(2-Pyrazolo[1,5-a]pyridin-3-ylcyclopropyl)benzenesulfonamide;

4-(2-Quinoxalin-6-ylcyclopropyl)benzenesulfonamide;

4-[2-[3-(Trifluoromethyl)cinnolin-7-yl] cyclopropyl]benzenesulfonamide;

4-[2-(3-Chloro-7-isoquinolyl)cyclopropyl]benzenesulfonamide;

4-(2-Thieno[2,3-c]pyridin-2-ylcyclopropyl)benzenesulfonamide;

4-[2-(1,7-Naphthyridin-2-yl)cyclopropyl]benzenesulfonamide;

4-[2-(1-Methylindazol-5-yl)cyclopropyl]benzenesulfonamide;

4-[2-(4,5,6,7-Tetrahydropyrazolo[1,5-a]pyridin-2-yl)cyclopropyl]benzenesulfonamide;

4-(2-Furo[2,3-b]pyridin-5-ylcyclopropyl)benzenesulfonamide;

4-[2-(2-Methylindazol-6-yl)cyclopropyl]benzenesulfonamide;

4-[2-(4-Methyl-2,3-dihydropyrido[3,2-b][1,4]oxazin-7-yl)cyclopropyl]benzenesulfonamide; and

4-[2-(5,6,7,8-Tetrahydroquinolin-3-yl)cyclopropyl]benzenesulfonamide;

or a pharmaceutically acceptable salt thereof.

9. A pharmaceutical composition comprising (i) a pharmaceutically acceptable carrier and (ii) a compound according to claim 1 or a pharmaceutically acceptable salt thereof.

10. The pharmaceutical composition of claim 9 , further comprising a second therapeutic agent selected from the group consisting of acetylcholinesterase inhibitors; NMDA receptor antagonists; antipsychotics; MAO-B inhibitors; and levodopa.

11. A method of treating a patient with cognitive impairments associated with Alzheimer's disease, Parkinson's disease, and schizophrenia, the method comprising administering to the patient the compound according to claim 1 , or a pharmaceutically acceptable salt thereof, in an amount effective to treat the patient.

12. A method of modulating α7 nAChR activity in a mammal comprising administering to the mammal an effective amount of compound according to claim 1 or a pharmaceutically acceptable salt thereof.

13. A method of treating a patient with mild to moderate dementia of the Alzheimer's type, the method comprising administering to the patient the compound according to claim 1 or a pharmaceutically acceptable salt thereof, in an amount effective to treat the patient.