Azetidine derivatives

1. A method of treatment of a disease or medical condition which benefits from inhibition of FAAH activity, wherein the disease or condition is selected from vomiting, nausea, depression, anxiety, spinal cord injury, and schizophrenia, comprising administering to a subject suffering such disease or condition an effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof:

wherein

Ar 1 is optionally substituted phenyl or optionally substituted monocyclic heteroaryl having 5 or 6 ring atoms;

Ar 2 is optionally substituted phenyl, optionally substituted monocyclic heteroaryl having 5 or 6 ring atoms or optionally substituted fused bicyclic heteroaryl having 5 or 6 ring atoms in each fused ring; and

Ar 3 is a divalent radical selected from the group consisting of optionally substituted phenylene and optionally substituted monocyclic heteroarylene radicals having 5 or 6 ring atoms.

2. The method as claimed in claim 1 wherein Ar 1 is optionally substituted phenyl.

3. The method as claimed in claim 1 wherein Ar 2 is phenyl, pyridyl, pyrimidinyl, pyrazinyl or pyridazinyl, any of which being optionally substituted.

4. The method as claimed in claim 1 wherein Ar 2 is 3-pyridyl, pyrimidin-4-yl, pyrazin-2-yl or pyridazin-3-yl, any of which being optionally substituted.

5. The method as claimed in claim 1 wherein Ar 3 is an optionally substituted divalent phenylene or pyridinylene radical.

6. The method as claimed in claim 5 wherein Ar 3 is an optionally substituted divalent 1,4-phenylene or a 2,5-pyridinylene radical of formula:

wherein the bond marked with a single asterisk is attached to Ar 1 and the bond marked with a double asterisk is attached to the oxygen.

7. The method as claimed in claim 1 wherein any optional substituents in Ar 1 , Ar 2 and Ar 3 are independently selected from chloro, fluoro, bromo, cyclopropyl, methyl, mono-, di- or tri-methyl, trifluoromethyl, difluoromethyl, monofluoromethyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, 2-methoxyethoxy, 2-benzyloxy-ethoxy, 2-hydroxy-ethoxy, mono-, di- or tri-fluoromethoxy, cyano, hydroxyl; —CO 2 R 1 and —SO 2 R 1 wherein R 1 is hydrogen, methyl or ethyl; tetrazolyl; —NR 2 R 3 , —CH 2 NR 2 R 3 and —C(═O)NR 2 R 3 wherein R 2 and R 3 are independently hydrogen, methyl or ethyl.

8. The method as claimed in claim 1 wherein:

Ar 2 is 3-pyridyl, pyrimidin-4-yl, pyrazin-2-yl or pyridazin-3-yl;

Ar 3 is an optionally substituted divalent 1,4-phenylene or a 2,5-pyridinylene radical of formula:

wherein the bond marked with a single asterisk is attached to Ar 1 and the bond marked with a double asterisk is attached to the oxygen; and

Ar 1 is optionally substituted phenyl.

9. The method as claimed in claim 8 wherein Ar 1 is phenyl, 2-fluorophenyl, 3-(2-methoxy-ethoxy)-phenyl, or 2-methoxy-5-(2-methoxy-ethoxy)-phenyl.

10. The method as claimed in claim 8 wherein Ar 2 is pyridazin-3-yl.

11. The method as claimed in claim 1 , wherein the compound is selected from the group consisting of

3-(biphenyl-4-yloxy)-azetidine-1-carboxylic acid phenylamide,

3-(biphenyl-4-yloxy)-azetidine-1-carboxylic acid (3-fluoro-phenyl)-amide,

3-(biphenyl-4-yloxy)-azetidine-1-carboxylic acid (2-fluoro-phenyl)-amide,

3-(biphenyl-4-yloxy)-azetidine-1-carboxylic acid pyridin-3-ylamide,

3{-5-[3-(2-methoxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyrimidin-4-ylamide,

3{-5-[3-(2-methoxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyrazin-2-ylamide,

3{-5-[3-(2-ethoxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3{-5-[3-(2-ethoxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyridin-3-ylamide,

3{-5-[3-(2-benzyloxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-{5-[3-(2-hydroxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-{5-[2-methoxy-5-(2-methoxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-[5-(2,5-dimethoxy-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-(5-phenyl-pyridin-2-yloxy)-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-[5-(2,6-difluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-{5-[2-chloro-5-(2-methoxy-ethoxy)-phenyl]-pyridin-2-yloxy}-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-[5-(2-fluoro-phenyl]-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyrazin-2-ylamide,

3-[5-(2-methoxy-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyridazin-3-ylamine,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-[5-(2-fluoro-3-methoxy-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyridazin-3-ylamide,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid (6-methyl-pyridazin-3-yl)-amide,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid (6-methoxy-pyridazin-3-yl)-amide,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid (5-methyl-[1,3,4]oxadiazol-2-yl)-amide,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid pyridazin-4-ylamide,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid (5-methyl-pyridazin-3-yl)-amide,

3-[5-(2-fluoro-phenyl)-pyridin-2-yloxy]-azetidine-1-carboxylic acid (4-methyl-pyridazin-3-yl)-amide,

or a pharmaceutically salt thereof.

12. The method of claim 1 , wherein the disease or condition is selected from vomiting and nausea.

13. The method of claim 1 , wherein the disease or condition is selected from depression, anxiety, spinal cord injury, and schizophrenia.