Pharmaceutical compounds

1. A compound of the formula (1):

or a salt thereof, wherein:

R 1 is selected from NR 5 R 6 ; an optionally substituted 5- or 6-membered ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof; or

R 1 is linked to R 2 to form an optionally substituted spirocyclic group;

R 2 is selected from hydrogen; fluorine; cyano; hydroxy; amino; and a C 1-3 non-aromatic hydrocarbon group which is optionally substituted with one to six fluorine atoms and wherein one of the carbon atoms of the hydrocarbon group may optionally be replaced by a heteroatom selected from O, N and S and oxidized forms thereof, or R 2 is linked to R 1 to form an optionally substituted spirocyclic group;

R 4 is H or a C 1-6 non-aromatic hydrocarbon group which is optionally substituted with one to six fluorine atoms and wherein one or two, but not all, carbon atoms of the hydrocarbon group may optionally be replaced by a heteroatom selected from O, N and S and oxidised forms thereof;

R 5 is COR 7 , a non-aromatic C 1-6 hydrocarbon group optionally substituted with one or more fluorine atoms or optionally substituted with a 5- or 6-membered ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof, or R 5 can be joined together with R 6 to form an optionally substituted monocyclic or bicyclic ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof,

R 6 is hydrogen, a non-aromatic C 1-6 hydrocarbon group optionally substituted with one or more fluorine atoms or optionally substituted with a 5- or 6-membered optionally substituted ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof, or R 6 can be joined together with R 5 or R 7 to form an optionally substituted monocyclic or bicyclic ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof,

R 7 is a non-aromatic C 1-6 hydrocarbon group optionally substituted with one or more fluorine atoms, or R 7 can be joined together with R 6 to form an optionally substituted monocyclic or bicyclic ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof.

2. The compound according to claim 1 wherein R 1 is selected from NR 5 R 6 ; an optionally substituted 5- or 6-membered ring containing 1 or 2 heteroatoms selected from O or N; or R 1 is linked to R 2 to form an optionally substituted spirocyclic ring having 3, 4 or 5 atoms containing 0, 1 or 2 heteroatoms selected from O or N.

3. The compound according to claim 1 wherein R 1 is linked to R 2 to form an optionally substituted spirocyclic ring having 3, 4 or 5 atoms containing 0, 1 or 2 heteroatoms selected from O or N, wherein the optional substituents are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino or a further fused ring.

4. The compound according to claim 1 wherein R 1 is an optionally substituted 5- or 6-membered aromatic ring containing 1 or 2 nitrogen heteroatoms, wherein the optional substituents are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino.

5. The compound according to claim 2 wherein R 1 is NR 5 R 6 .

6. The compound according to claim 5 wherein R 5 is selected from COR 7 , a non-aromatic C 1-6 hydrocarbon group optionally substituted with a 6-membered aromatic ring containing 0, 1, or 2 nitrogen heteroatoms, or R 5 can be joined together with R 6 to form an optionally substituted monocyclic or bicyclic ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof, or R 7 can be joined together with R 6 to form an optionally substituted monocyclic or bicyclic ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof.

7. The compound according to claim 6 wherein R 5 is selected from COCH 3 , a non-aromatic C 1-6 hydrocarbon group or R 5 can be joined together with R 6 to form an optionally substituted monocyclic ring, wherein the optional substituents are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino, wherein the C 1 -C 3 alkyl or C 1 -C 3 alkoxy groups can have an optional substituent selected from halogen, cyano, oxo, hydroxyl or amino, or R 5 is COR 7 where R 7 can be joined together with R 6 to form an optionally substituted monocyclic ring, wherein the optional substituents are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino, wherein the C 1 -C 3 alkyl or C 1 -C 3 alkoxy groups can have an optional substituent selected from halogen, cyano, oxo, hydroxyl or amino.

8. The compound according to claim 5 wherein R 6 is selected from hydrogen, a non-aromatic C 1-6 hydrocarbon group optionally substituted with a 6-membered optionally substituted aromatic ring containing 0, 1, or 2 nitrogen heteroatoms, or R 6 can be joined together with R 5 or R 7 to form an optionally substituted monocyclic or bicyclic ring containing 0, 1, 2 or 3 heteroatoms selected from O, N and S and oxidized forms thereof.

9. The compound according to claim 8 wherein R 6 is selected from hydrogen, a non-aromatic C 1-6 hydrocarbon group optionally substituted with an optionally substituted phenyl ring, wherein the optional substituents on the phenyl ring are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino, wherein the C 1 -C 3 alkyl or C 1 -C 3 alkoxy groups can have an optional substituent selected from halogen, cyano, oxo, hydroxyl or amino, or R 6 can be joined together with R 5 or R 7 to form an optionally substituted monocyclic ring wherein the optional substituents are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino, wherein the C 1 -C 3 alkyl or C 1 -C 3 alkoxy groups can have an optional substituent selected from halogen, cyano, oxo, hydroxyl or amino.

10. The compound according to claim 1 wherein R 2 is H or R 2 is linked to R 1 to form an optionally substituted spirocyclic ring having 3, 4 or 5 atoms containing 0, 1 or 2 heteroatoms selected from O or N, wherein the optional substituents are selected from C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, cyano, oxo, hydroxyl or amino or a further fused ring.

11. The compound according to claim 1 wherein R 1 and R 2 together represent a moiety which is selected from:

12. A compound according to claim 1 wherein R 4 is selected from H, methyl, ethyl, ethynyl and 1-propynyl.

13. A compound according to claim 1 wherein the compound is selected from:

Ethyl 7-[4-(1H-pyrazol-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-(4-chloro-1H-pyrazol-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-(4-methyl-1H-pyrazol-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-(6-methoxypyridin-2-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-(2-methoxypyridin-3-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-(2-oxo-1,2-dihydropyridin-3-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-cyano-4-(pyridin-2-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-{4-[(2R)-4,4-difluoro-2-(hydroxymethyl)pyrrolidin-1-yl]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(6-azaspiro[2.5]oct-6-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(3-oxo-2,8-diazaspiro[4.5]dec-8-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(2-oxo-1-oxa-3,8-diazaspiro[4.5]dec-8-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(4-ethyl-2-oxo-1-oxa-3,8-diazaspiro[4.5]dec-8-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(2-oxo-1,2-dihydro-1′H-spiro[indole-3,4′-piperidin]-1′-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-{4-[acetyl(2-methylpropyl)amino]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-{4-[acetyl(2,2-dimethylpropyl)amino]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(4-{acetyl[(1-methylcyclopropyl)methyl]amino}piperidin-1-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(4-{acetyl[(1-methylcyclobutyl)methyl]amino}piperidin-1-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-{4-[acetyl(benzyl)amino]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-(2-oxo-1,4′-bipiperidin-1′-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Ethyl 7-[4-(2-oxoazepan-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(4-(N-((1-methylcyclobutyl)methyl)acetamido)piperidin-1-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(4-(N-benzylacetamido)piperidin-1-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(1H-pyrazol-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(4-chloro-1H-pyrazol-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(4-methyl-1H-pyrazol-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(6-methoxypyridin-2-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(2-methoxypyridin-3-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(2-oxo-1,2-dihydropyridin-3-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-cyano-4-(pyridin-2-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-{4-[(2R)-4,4-difluoro-2-(hydroxymethyl)pyrrolidin-1-yl]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(6-azaspiro[2.5]oct-6-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate

Methyl 7-(3-oxo-2,8-diazaspiro[4.5]dec-8-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(2-oxo-1-oxa-3,8-diazaspiro[4.5]dec-8-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(4-ethyl-2-oxo-1-oxa-3,8-diazaspiro[4.5]dec-8-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(2-oxo-1,2-dihydro-1′H-spiro[indole-3,4′-piperidin]-1′-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-{4-[acetyl(2-methylpropyl)amino]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-{4-[acetyl(2,2-dimethylpropyl)amino]piperidin-1-yl}-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(4-{acetyl[(1-methylcyclopropyl)methyl]amino}piperidin-1-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(4-{acetyl[(1-methylcyclobutyl)methyl]amino}piperidin-1-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-(2-oxo-1,4′-bipiperidin-1′-yl)-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

Methyl 7-[4-(2-oxoazepan-1-yl)piperidin-1-yl]-3-oxa-9-azabicyclo[3.3.1]nonane-9-carboxylate;

or a salt thereof.

14. A pharmaceutical composition comprising a compound as defined in claim 1 and a pharmaceutically acceptable excipient.

15. A method of treating a cognitive disorder or psychotic disorder or for the treatment or lessening the severity of acute, chronic, neuropathic, or inflammatory pain comprising administering an effective amount of the compound according to claim 1 to a subject in need thereof.

16. The method according to claim 15 wherein the cognitive disorder is Alzheimer's disease.

17. The method according to claim 15 wherein the cognitive disorder is dementia with Lewy bodies.

18. The method according to claim 15 wherein the psychotic disorder is schizophrenia.