Positive allosteric modulators of the α7 nicotinic acetylcholine receptor and uses thereof

1. A compound of formula (I) or a salt thereof:

wherein

R 1 is selected from optionally substituted aryl, optionally substituted heteroaryl (excluding optionally substituted porphyrins), or optionally substituted heterocyclyl;

R 2 is selected from C 1 -C 4 alkyl, C 3 -C 5 alkenyl, F, Br, Cl, CN, or C 1 -C 4 haloalkyl;

R 3 is selected from hydrogen, C 1 -C 4 alkyl, C 3 -C 5 alkenyl, F, Br, Cl, CN, or C 1 -C 4 haloalkyl; or

R 2 and R 3 together form C 4-9 cycloalkyl or C 4-9 cycloalkenyl;

R 4 is selected from optionally substituted heteroaryl, optionally substituted heterocyclyl, or optionally substituted aryl;

R 5 is selected from hydrogen or optionally substituted alkyl;

wherein when both R 2 and R 3 are Cl, R 4 is an optionally substituted heteroaryl or optionally substituted heterocyclyl, and

provided that the following compounds are excluded:

2. A compound of formula (II) or a salt thereof:

wherein

R 1 is selected from optionally substituted aryl, optionally substituted heteroaryl or optionally substituted heterocyclyl;

R 2 and R 3 together form C 4-9 cycloalkyl;

R 4 is selected from optionally substituted heteroaryl, optionally substituted heterocyclyl, or optionally substituted aryl; and

R 5 is selected from hydrogen or optionally substituted alkyl.

3. A compound according to claim 1 , represented by formula (Ia), or a salt thereof:

wherein

each R 1 ′ is independently selected from the group consisting of cyano, halo, nitro, optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aryloxy, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted C 3-7 cycloalkyl, —OR, —C(O)R, —C(O)OR, —OC(O)R (where R is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted C 3-7 cycloalkyl, optionally substituted heterocyclyl, optionally substituted heteroaryl, and optionally substituted aryl), —C(O)NR′R″, —NR′C(O)R″, —S(O) 2 —NR′R″ and —NR′R″ (where R′ and R″ are independently selected from hydrogen or lower alkyl), —S(O)R′″ (where R′″ is lower alkyl, or cycloalkyl), —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH), or any two adjacent R 1 ′ together form heterocyclyl or heteroaryl;

n is 0 or an integer from 1 to 5;

R 2 is selected from C 1 -C 4 alkyl, C 3 -C 5 alkenyl, F, Br, Cl, CN, or C 1 -C 4 haloalkyl;

R 3 is selected from hydrogen, C 1 -C 4 alkyl, C 3 -C 5 alkenyl, F, Br, Cl, CN, or C 1 -C 4 haloalkyl; or

R 2 and R 3 together form C 4-9 cycloalkyl or C 4-9 cycloalkenyl;

R 4 is selected from optionally substituted heteroaryl, optionally substituted heterocyclyl, or optionally substituted aryl;

R 5 is selected from hydrogen or optionally substituted alkyl;

wherein when both R 2 and R 3 are Cl, R 4 is an optionally substituted heteroaryl or optionally substituted heterocyclyl, and

provided that the following compounds are excluded:

4. A compound according to claim 1 , represented by formula (Ib), or a salt thereof:

wherein

each R 1 ′ is independently selected from the group consisting of cyano, halo, nitro, optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aryloxy, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted C 3-7 cycloalkyl, —OR, —C(O)R, —C(O)OR, —OC(O)R (where R is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted C 3-7 cycloalkyl, optionally substituted heterocyclyl, optionally substituted heteroaryl, and optionally substituted aryl), —C(O)NR′R″, —NR′C(O)R″, —S(O) 2 —NR′R″ and —NR′R″ (where R′ and R″ are independently selected from hydrogen or lower alkyl), —S(O)R′″ (where R′″ is lower alkyl, or cycloalkyl), —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH), or any two adjacent R 1 ′ together form heterocyclyl or heteroaryl;

n is 0 or an integer from 1 to 5;

R 2 is selected from C 1 -C 4 alkyl, C 3 -C 5 alkenyl, C 1 -C 4 haloalkyl, F, Cl or Br;

R 3 is selected from hydrogen, C 1 -C 4 alkyl, C 3 -C 5 alkenyl, C 1 -C 4 haloalkyl, or Br; or

R 2 and R 3 together form C 4-9 cycloalkyl or C 4-9 cycloalkenyl;

R 4 is selected from optionally substituted heteroaryl, optionally substituted heterocyclyl, or optionally substituted aryl;

R 5 is independently selected from hydrogen, or optionally substituted alkyl;

provided that the following compound is excluded:

5. A compound according to claim 1 , represented by formula (Ic), or a salt thereof:

wherein

each R 1 ′ is independently selected from the group consisting of cyano, halo, nitro, optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aryloxy, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted C 3-7 cycloalkyl, —OR, —C(O)R, —C(O)OR, —OC(O)R (where R is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted C 3-7 cycloalkyl, optionally substituted heterocyclyl, optionally substituted heteroaryl, and optionally substituted aryl), —C(O)NR′R″, —NR′C(O)R″, —S(O) 2 —NR′R″ and —NR′R″ (where R′ and R″ are independently selected from hydrogen or lower alkyl), —S(O)R′″ (where R′″ is lower alkyl, or cycloalkyl), —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH), or any two adjacent R 1 ′ together form heterocyclyl or heteroaryl;

n is 0 or an integer from 1 to 5;

R 2 is selected from C 1 -C 4 alkyl, C 3 -C 5 alkenyl, C 1 -C 4 haloalkyl, F, Cl or Br;

R 3 is selected from hydrogen, C 1 -C 4 alkyl, C 3 -C 5 alkenyl, C 1 -C 4 haloalkyl, or Br; or

R 2 and R 3 together form C 4-9 cycloalkyl or C 4-9 cycloalkenyl;

R 4 is selected from heteroaryl which may be independently substituted by one to three substituents selected from halogen, C 1-6 alkyl, C 1-6 alkoxy, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, C 1-6 haloalkoxy, —OH, phenyl, benzyl, phenoxy, benzyloxy, benzoyl, —NH 2 , —NHC 1-4 alkyl, —N(C 1-4 alkyl) 2 , —CN, —NO 2 , mercapto, —S(O) 2 NH 2 , —S(O) 2 NHC 1-4 alkyl, —S(O) 2 N(C 1-4 alkyl) 2 , C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, CO 2 H, —S(O)R′″ (where R′″ is lower alkyl or cycloalkyl) and —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH); or aryl which may be independently substituted by one to three substituents selected from halogen, C 2-6 alkyl, C 1-6 alkoxy, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, C 1-6 haloalkoxy, —OH, phenyl, benzyl, phenoxy, benzyloxy, benzoyl, —NH 2 , —NHC 1-4 alkyl, —N(C 1-4 alkyl) 2 , —CN, —NO 2 , mercapto, —S(O) 2 NH 2 , —S(O) 2 NHC 1-4 alkyl, —S(O) 2 N(C 1-4 alkyl) 2 , C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, CO 2 H, —S(O)R′″ (where R′″ is lower alkyl or cycloalkyl) and —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH); and

R 5 is independently selected from hydrogen, or lower alkyl.

6. A compound according to claim 1 , represented by formula (IIa), or a salt thereof:

wherein

each R 1 ′ is independently selected from the group consisting of cyano, halo, nitro, optionally substituted lower alkyl, optionally substituted aryl, optionally substituted aryloxy, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted C 3-7 cycloalkyl, —OR, —C(O)R, —C(O)OR, —OC(O)R (where R is selected from hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted C 3-7 cycloalkyl, optionally substituted heterocyclyl, optionally substituted heteroaryl, and optionally substituted aryl), —C(O)NR′R″, —NR′C(O)R″, —S(O) 2 —NR′R″ and —NR′R″ (where R′ and R″ are independently selected from hydrogen or lower alkyl), —S(O)R′″ (where R′″ is lower alkyl, or cycloalkyl), —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH), or any two adjacent R 1 ′ together form heterocyclyl or heteroaryl;

n is 0 an integer from 1 to 5;

R 2 and R 3 together form C 4-9 cycloalkyl;

R 4 is selected from optionally substituted heteroaryl, optionally substituted heterocyclyl, or optionally substituted aryl; and

R 5 is independently selected from hydrogen or optionally substituted alkyl.

7. A compound according to claim 1 or salt thereof, wherein R 1 is an optionally substituted aryl or optionally substituted heteroaryl group.

8. A compound according to claim 2 , or salt thereof, wherein R 1 is an optionally substituted aryl or optionally substituted heteroaryl group.

9. A compound according to claim 1 , or salt thereof, wherein R 4 is selected from heteroaryl or aryl each of which may be independently substituted by one to three substituents selected from halogen, C 1-6 alkyl, C 1-6 alkoxy, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, C 1-6 haloalkoxy, —OH, phenyl, benzyl, phenoxy, benzyloxy, benzoyl, —NH 2 , —NHC 1-4 alkyl, —N(C 1-4 alkyl) 2 , —CN, —NO 2 , mercapto, —S(O) 2 NH 2 , —S(O) 2 NHC 1-4 alkyl, —S(O) 2 N(C 1-4 alkyl) 2 , C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, CO 2 H, —S(O)R′″ (where R′″ is lower alkyl or cycloalkyl) and —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH).

10. A compound according to claim 1 , or salt thereof, where R 4 is selected from:

wherein

Hal is a halogen;

m is 0, 1 or 2; and

each R 6 is independently selected from halogen, hydroxy, CN, NO 2 , haloalkyl, aryl, heteroaryl, C 1-3 alkoxy, C 1-3 alkyl, or CO 2 R′ (where R′ is a lower alkyl or H);

or

(b) a heteroaryl substituted from 1 to 3 times from a group selected from C 1 -C 3 alkyl, C 1-6 alkoxy, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, C 1-6 haloalkoxy, —OH, phenyl, benzyl, phenoxy, benzyloxy, benzoyl, —NH 2 , —NHC 1-4 alkyl, —N(C 1-4 alkyl) 2 , —CN, —NO 2 , mercapto, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, CO 2 H, —S(O)R′″ (where R′″ is lower alkyl or cycloalkyl) and —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH).

11. A compound according to claim 10 , or a salt thereof, wherein the heteroaryl is pyridinyl, pyrazolyl or thiazolyl.

12. A compound according to claim 1 , or a salt thereof, wherein R 2 and R 3 are C 1 -C 4 alkyl.

13. A compound according to claim 1 , or a salt thereof, wherein R 2 and R 3 are methyl or ethyl.

14. A compound according to claim 1 , or a salt thereof, wherein R 5 is hydrogen or C 1-3 alkyl.

15. A compound according to claim 3 , or a salt thereof, wherein n is 0, 1, 2, or 3, and R 1 ′, when present, is halogen, C 1-6 alkyl, C 1-6 alkoxy, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 haloalkyl, C 1-6 haloalkoxy, —OH, phenyl, benzyl, phenoxy, benzyloxy, benzoyl, —NH 2 , —NHC 1-4 alkyl, —N(C 1-4 alkyl) 2 , —CN, —NO 2 , mercapto, —S(O) 2 NH 2 , —S(O) 2 NHC 1-4 alkyl, —S(O) 2 N(C 1-4 alkyl) 2 , C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, CO 2 H, —S(O)R′″ (where R′″ is lower alkyl or cycloalkyl) and —S(O) 2 R′″ (where R′″ is lower alkyl, cycloalkyl or OH).

16. A method for the treatment of cognitive deficits associated with neurodegeneration or neuropsychiatric diseases, said method including the step of administering a compound according to claim 1 , or a pharmaceutically acceptable salt thereof, or a composition comprising a compound according to claim 1 , or a pharmaceutically acceptable salt thereof.

17. A method for the treatment of inflammatory diseases, said method including the step of administering a compound according to claim 1 , or a pharmaceutically acceptable salt thereof, or a composition comprising a compound according to claim 1 , or a pharmaceutically acceptable salt thereof.

18. A method of positively modulating α7nAChRs in a cell by contacting the cell with a compound according to claim 1 , or a salt thereof, to said cell.