Antagonists of the muscarinic acetylcholine receptor M4

1. A compound of formula (I):

or a pharmaceutically acceptable salt thereof, wherein:

A is

Q is selected from NR a and O;

m is 0, 1, or 2;

R 1 is selected from halo, phenyl, and a 5- or 6-membered heteroaryl having 1, 2, or 3 heteroatoms independently selected from N, O, and S, wherein the phenyl and heteroaryl are unsubstituted or substituted with 1, 2, or 3 substituents independently selected from halo, C 1 -C 4 alkyl, and —NHCOR j , and R j is C 1 -C 4 alkyl;

R 2 is selected from hydrogen, C 1 -C 4 alkyl, halo, and OR f ;

R 3 is selected from hydrogen and C 1 -C 4 alkyl;

R 4 is selected from —(CR g R h ) p —Y′, and C 1 -C 8 alkyl;

R 5 is selected from hydrogen, C 1 -C 4 alkyl, halo, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, and C 1 -C 4 haloalkoxy;

R 6 is hydrogen; or R 6 is taken together with R 5 and the carbon atoms to which they are attached to form a C 3 -C 6 cycloalkyl;

Y′ is selected from C 3 -C 10 cycloalkyl, C 3 -C 8 cycloalkenyl, phenyl, a 5- to 6-membered monocyclic heterocycle having 1 or 2 heteroatoms independently selected from N, O, and S, and a 5- to 6-membered monocyclic heteroaryl having 1, 2, or 3 heteroatoms independently selected from N, O, and S, wherein Y′ is unsubstituted or substituted with one or two substituents independently selected from halo and C 1 -C 4 alkyl;

each R a and R f is independently selected from hydrogen and C 1 -C 4 alkyl;

R g is hydrogen;

R h is hydrogen; and

p is 0 or 1.

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

Q is NR a ; and

R a is hydrogen.

3. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

Q is O.

4. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 2 is hydrogen.

5. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 3 is hydrogen.

6. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

R 6 is hydrogen.

7. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein

m is 2; and

one R 5 is taken together with R 6 and the carbon atoms to which they are attached, form a C 3 cycloalkyl ring.

8. The compound of claim 1 , wherein the compound is a compound of formula (Ia):

or a pharmaceutically acceptable salt thereof.

9. The compound of claim 1 , wherein the compound is a compound of formula (Ib):

or a pharmaceutically acceptable salt thereof.

10. The compound of claim 1 , wherein the compound is selected from:

N-(4-(6-((2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptan-6-yl)amino)pyridazin-3-yl)phenyl)acetamide;

N-(6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)-2-((tetrahydro-2H-pyran-4-yl)methyl)-2-azaspiro[3.3]heptan-6-amine;

2-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-N-(6-(2-chloro-5-fluorophenyl)pyridazin-3-yl)-2-azaspiro[3.3]heptan-6-amine;

N-(6-(2-chloro-5-fluorophenyl)pyridazin-3-yl)-2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptan-6-amine;

N-(6-(2-chloro-5-fluorophenyl)pyridazin-3-yl)-2-(cyclohexylmethyl)-2-azaspiro[3.3]heptan-6-amine;

N-(6-(2-chloro-5-fluorophenyl)pyridazin-3-yl)-2-((tetrahydro-2H-pyran-3-yl)methyl)-2-azaspiro[3.3]heptan-6-amine;

N-(6-(2-chloro-5-fluorophenyl)pyridazin-3-yl)-2-((tetrahydro-2H-pyran-4-yl)methyl)-2-azaspiro[3.3]heptan-6-amine;

2-(adamantan-1-ylmethyl)-N-(6-(2-chloro-5-fluorophenyl)pyridazin-3-yl)-2-azaspiro[3.3]heptan-6-amine;

N-(6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)-2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptan-6-amine;

N-(4-(6-((2-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-2-azaspiro[3.3]heptan-6-yl)amino)pyridazin-3-yl)phenyl)acetamide;

6-(1,4-dimethyl-1H-pyrazol-5-yl)-N-((2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptan-6-yl)methyl)pyridazin-3-amine;

N-((2-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-2-azaspiro[3.3]heptan-6-yl)methyl)-6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-amine;

6-(1,3-dimethyl-1H-pyrazol-4-yl)-N-((2-(2,3,3-trimethylbutyl)-2-azaspiro[3.3]heptan-6-yl)methyl)pyridazin-3-amine;

N-((2-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-2-azaspiro[3.3]heptan-6-yl)methyl)-6-(2-chloro-5-fluorophenyl)pyridazin-3-amine;

6-(1,3-dimethyl-1H-pyrazol-4-yl)-N-((2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptan-6-yl)methyl)pyridazin-3-amine;

N-((2-(cyclohexylmethyl)-2-azaspiro[3.3]heptan-6-yl)methyl)-6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-amine;

N-(4-(6-(((2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptan-6-yl)methyl)amino)pyridazin-3-yl)phenyl)acetamide;

N-(4-(6-(((2-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-2-azaspiro[3.3]heptan-6-yl)methyl)amino)pyridazin-3-yl)phenyl)acetamide;

N-(4-(6-(((2-(cyclohexylmethyl)-2-azaspiro[3.3]heptan-6-yl)methyl)amino)pyridazin-3-yl)phenyl)acetamide;

6-chloro-N-((7-(3,3-dimethylbutyl)-7-azadispiro[2.1.3 5 .1 3 ]nonan-1-yl)methyl)pyridazin-3-amine;

2-(cyclohexylmethyl)-6-(((6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)oxy)methyl)-2-azaspiro[3.3]heptane;

6-(((6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)oxy)methyl)-2-(3,3-dimethylbutyl)-2-azaspiro[3.3]heptane;

2-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)-6-(((6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)oxy)methyl)-2-azaspiro[3.3]heptane;

2-benzyl-6-(((6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)oxy)methyl)-2-azaspiro[3.3]heptane; and

6-(((6-(1,3-dimethyl-1H-pyrazol-4-yl)pyridazin-3-yl)oxy)methyl)-2-((3-methylpyridin-2-yl)methyl)-2-azaspiro[3.3]heptane,

or a pharmaceutically acceptable salt thereof.

11. A pharmaceutical composition comprising a compound of claim 1 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

12. A method for antagonizing mAChR M 4 in a subject in need thereof, comprising a step of administering to the subject a therapeutically effective amount a compound of claim 1 , or a pharmaceutically acceptable salt thereof.

13. The method of claim 12 , wherein the subject has a neurodegenerative disorder, a movement disorder or a brain disorder.

14. The method of claim 13 , wherein the subject has a movement disorder.

15. The method of claim 12 , wherein the subject has a disorder selected from Parkinson's disease, drug-induced Parkinsonism, dystonia, Tourette's syndrome, dyskinesias, schizophrenia, cognitive deficits associated with schizophrenia, excessive daytime sleepiness, attention deficit hyperactivity disorder (ADHD), Huntington's disease, chorea, cerebral palsy, and progressive supranuclear palsy.

16. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is a 5-membered heteroaryl having 1 or 2 nitrogen atoms, wherein the heteroaryl is unsubstituted or substituted with 1 or 2 substituents independently selected from C 1 -C 4 alkyl.

17. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is pyrazolyl having 2 substituents independently selected from C 1 -C 4 alkyl.

18. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein R 1 is 1,3-dimethyl-1H-pyrazol-4-yl or 1,4-dimethyl-1H-pyrazol-5-yl.

19. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein Y′ is selected from cyclohexyl, adamantyl, bicyclo[2.2.1]hept-5-enyl, phenyl, tetrahydropyranyl, and pyridinyl; wherein Y′ is unsubstituted or substituted with one or two substituents independently selected from halo and C 1 -C 4 alkyl.

20. The compound of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the group —CHR 3 R 4 has a formula selected from: