1,2-substituted cyclopentanes as orexin receptor antagonists

1. A compound of formula

wherein

R 1 represents a 5- or 6-membered heteroaryl group optionally substituted by at least one substituent selected from halogen, cyano, hydroxyl, C 3 -C 6 cycloalkyl, C 1 -C 3 alkyl, C 1 -C 3 alkoxy, C 1 -C 3 alkoxycarbonyl, C 1 -C 3 alkoxycarbonylamino, C 1 -C 3 haloalkyl, C 1 -C 3 haloalkoxy, —NR 4 R 5 , C 3 -C 6 cycloalkylamino, C 1 -C 3 alkylcarbonyloxy, C 1 -C 3 alkylcarbonylamino, sulphonamido, C 1 -C 3 alkylsulphonyl, C 1 -C 3 alkylsulphonylamino and —C(O)NR 6 R 7 ;

L represents NR 12 ;

R a represents a hydrogen atom;

R b represents a hydrogen atom;

X represents CF 2 ;

R 2 represents a hydrogen atom;

R 3 represents a phenyl group or a 5- or 6-membered heteroaryl group, all optionally substituted by at least one substituent independently selected from halogen, hydroxyl, cyano, C 1 -C 3 alkyl, C 1 -C 3 haloalkyl, C 1 -C 3 hydroxyalkyl, C 1 -C 3 alkoxy, C 1 -C 3 haloalkoxy, C 2 -C 4 alkenyl, C 1 -C 3 alkylcarbonyloxy, C 1 -C 3 alkoxycarbonyl, —NR 8 R 9 , —C(O)NR 10 R 11 , C 3 -C 6 cycloalkyl, C 3 -C 6 cycloalkyloxy, C 3 -C 6 cycloalkylmethyl or a 5- or 6-membered heteroaryl group, the heteroaryl group itself being optionally substituted by at least one substituent independently selected from C 1 -C 6 alkyl, C 1 -C 6 alkoxy and C 1 -C 6 haloalkoxy;

R 4 and R 5 each independently represent a hydrogen atom or a C 1 -C 3 alkyl or C 3 -C 6 cycloalkyl group, or R 4 and R 5 may together with the nitrogen atom to which they are attached form a 4- to 7-membered saturated heterocyclic ring optionally substituted by at least one substituent independently selected from halogen, hydroxyl and C 1 -C 3 alkoxy;

R 6 and R 7 each independently represent a hydrogen atom or a C 1 -C 3 alkyl or C 3 -C 6 cycloalkyl group, or R 6 and R 7 may together with the nitrogen atom to which they are attached form a 4- to 7-membered saturated heterocyclic ring optionally substituted by at least one substituent independently selected from halogen and hydroxyl;

R 8 and R 9 each independently represent a hydrogen atom or a C 1 -C 3 alkyl or C 3 -C 6 cycloalkyl group, or R 8 and R 9 may together with the nitrogen atom to which they are attached form a 4- to 7-membered saturated heterocyclic ring optionally substituted by at least one substituent independently selected from halogen, hydroxyl and C 1 -C 3 alkoxy;

R 10 and R 11 each independently represent a hydrogen atom or a C 1 -C 3 alkyl or C 3 -C 6 cycloalkyl group, or R 10 and R 11 may together with the nitrogen atom to which they are attached form a 4- to 7-membered saturated heterocyclic ring optionally substituted by at least one substituent independently selected from halogen and hydroxyl; and

R 12 represents a hydrogen atom;

or a pharmaceutically acceptable salt thereof.

2. The compound according to claim 1 , wherein R 1 represents a 5- or 6-membered heteroaryl group containing one or two ring heteroatoms independently selected from nitrogen, oxygen and sulphur, the heteroaryl group being optionally substituted by one or two substituents independently selected from halogen, C 1 -C 3 alkyl, and C 1 -C 3 haloalkyl.

3. The compound according to claim 1 , wherein R 1 represents a 5- or 6-membered heteroaryl group selected from pyridinyl, pyrimidinyl and pyrazinyl.

4. The compound according to claim 3 , wherein R 1 represents a group selected from:

(i) 4-(trifluoromethyl)pyridin-2-yl,

(ii) 5-(trifluoromethyl)pyridin-2-yl,

(iii) 5-(trifluoromethoxy)pyridin-2-yl,

(iv) 6-(trifluoromethyl)pyridin-2-yl,

(v) 6-(trifluoromethyl)pyridin-2-yl,

(vi) 5-chloropyridin-2-yl,

(vii) 5-bromopyridin-2-yl,

(viii) 3-fluoro-5-(trifluoromethyl)pyridin-2-yl,

(ix) 3-chloro-5-(trifluoromethyl)pyridin-2-yl,

(x) 3-bromo-5-(trifluoromethyl)pyridin-2-yl,

(xi) 5-bromo-3-methoxypyridin-2-yl,

(xii) 3-methyl-5-(trifluoromethyl)pyridin-2-yl,

(xiii) 5-(trifluoromethyl)pyrimidin-2-yl,

(xiv) 5-ethylpyrimidin-2-yl,

(xv) 5-(trifluoromethyl)pyrazin-2-yl,

(xvi) 5-chloropyrazin-2-yl,

(xvii) 5-(ethyl)pyrazin-2-yl,

(xviii) 5-(cyclopropyl)pyrazin-2-yl,

(xix) 5-(isopropyl)pyrazin-2-yl,

(xx) 3-methyl-5-(trifluoromethyl)pyrazin-2-yl,

(xxi) 3-ethyl-5-(trifluoromethyl)pyrazin-2-yl,

(xxii) 3-cyclopropyl-5-(trifluoromethyl)pyrazin-2-yl, and

(xxiii) 3-isopropyl-5-(trifluoromethyl)pyrazin-2-yl.

5. The compound according to claim 4 , wherein R 1 represents (xxi) 3-ethyl-5-(trifluoromethyl)pyrazin-2-yl.

6. The compound according to claim 1 , wherein R 3 represents a 5- or 6-membered heteroaryl group selected from pyridinyl, pyrimidinyl and pyrazinyl, all optionally substituted as claimed in claim 1 .

7. The compound according to claim 1 , wherein R 3 represents a phenyl group optionally substituted by at least one substituent independently selected from fluorine, chlorine, C 1 -C 3 alkyl, C 1 -C 3 alkoxy or a 5- or 6-membered heteroaryl group, the heteroaryl group itself being optionally substituted by one or two substituents independently selected from C 1 -C 2 alkyl, C 1 -C 2 alkoxy and C 1 -C 2 haloalkoxy.

8. The compound according to claim 1 , wherein R 3 represents a group selected from:

(i) 2-fluorophenyl,

(ii) 2-chlorophenyl,

(iii) 2-methylphenyl,

(iv) 2-cyclopropylphenyl,

(v) 2-methoxyphenyl,

(vi) 2-ethoxyphenyl,

(vii) 2-(difluoromethoxy)phenyl,

(viii) 3-methylphenyl,

(ix) 3-methoxyphenyl,

(x) 2,6-difluorophenyl,

(xi) 2,6-dichlorophenyl,

(xii) 2,6-dimethoxyphenyl,

(xiii) 2,6-diethoxyphenyl,

(xiv) 2-ethoxy-5-methylphenyl,

(xv) 2,5-dimethoxyphenyl,

(xvi) 2-fluoro-6-methoxyphenyl,

(xvii) 5-fluoro-2-methoxyphenyl,

(xviii) 3-fluoro-2-methoxyphenyl,

(xix) 2-(1H-1,2,4-triazol-1-yl)phenyl,

(xx) 2-(2H-1,2,3-triazol-2-yl)phenyl,

(xxi) 5-methyl-2-(1H-1,2,3-triazol-1-yl)phenyl,

(xxii) 5-methyl-2-(2H-1,2,3-triazol-2-yl)phenyl,

(xxiii) 5-fluoro-2-(1H-1,2,3-triazol-1-yl)phenyl,

(xxiv) 5-fluoro-2-(2H-1,2,3-triazol-2-yl)phenyl,

(xxv) 2-(3-methyl-1,2,4-oxadiazol-5-yl)phenyl,

(xxvi) 2-(pyrimidin-2-yl)phenyl,

(xxvii) 5-fluoro-2-(pyrimidin-2-yl)phenyl,

(xxviii) 2-(1H-pyrazol-1-yl)phenyl,

(xxix) 2-(1H-imidazol-1-yl)phenyl,

(xxx) 2-(1H-1,2,3-triazol-1-yl)phenyl,

(xxxi) 2-(pyrimidin-2-yl)-5-fluorophenyl,

(xxxii) 2-fluoro-6-(2H-1,2,3-triazol-2-yl)phenyl,

(xxxiii) 2-methoxy-5-methylphenyl,

(xxxiv) 2-chloro-6-(2H-1,2,3-triazol-2-yl)phenyl,

(xxxv) 2-(5-methyl-1,3,4-oxadiazol-2-yl)phenyl,

(xxxvi) 5-trifluoromethyl-2-(2H-1,2,3-triazol-2-yl)phenyl,

(xxxvii) 2-fluoro-6-(pyrazol-1-yl)phenyl,

(xxxviii) 5-fluoro-2-(pyrazol-1-yl)phenyl,

(xxxix) 5-methyl-2-(pyrazol-1-yl)phenyl,

(xl) 2-bromo-6-methoxyphenyl,

(xli) 2-methoxy-6-(pyrazol-1-yl)phenyl,

(xlii) 5-chloro-2-(2H-1,2,3-triazol-2-yl)phenyl,

(xliii) 3-fluoro-2-(2H-1,2,3-triazol-2-yl)phenyl,

(xliv) 5-trifluoromethyl-2-(1H-1,2,3-triazol-1-yl)phenyl,

(xlv) 5-chloro-2-(1H-1,2,3-triazol-1-yl)phenyl,

(xlvi) 2,3-difluoro-6-(2H-1,2,3-triazol-2-yl)phenyl,

(xlvii) 5-cyclopropyl-2-(2H-1,2,3-triazol-2-yl)phenyl,

(xlviii) 5-chloro-2-(pyrazol-1-yl)phenyl,

(xlix) 3,5-difluoro-2-(2H-1,2,3-triazol-2-yl)phenyl,

(l) 2-(difluoromethyl)phenyl,

(li) 2-(trifluoromethyl)phenyl,

(lii) 3,6-difluoro-2-(2H-1,2,3-triazol-2-yl)phenyl,

(liii) 2-cyclopropyl-6-fluorophenyl,

(liv) 2-(5-ethoxypyrimidin-2-yl)phenyl,

(lv) 3-(pyrimidin-2-yl)pyridin-2-yl,

(lvi) 3-ethoxy-6-methylpyridin-2-yl,

(lvii) 3-(pyrazol-1-yl)pyridin-2-yl,

(lviii) 3-(piperidin-1-yl)pyridin-2-yl,

(lix) 3-(trifluoromethoxy)pyridin-2-yl,

(lx) 3-(ethoxy)pyridin-2-yl,

(lxi) 3-(cyclopropyl)pyridin-2-yl,

(lxii) 3-chloropyridin-2-yl,

(lxiii) 3-bromopyridin-2-yl,

(lxiv) 3-methoxypyridin-2-yl,

(lxv) 3-(propan-2-yloxy)pyridin-2-yl,

(lxvi) 6-bromo-3-methoxypyridin-2-yl,

(lxvii) 3-methoxy-6-methylpyridin-2-yl, and

(lxviii) 3-(2H-1,2,3-triazol-2-yl)pyridin-2-yl.

9. The compound according to claim 8 , wherein R 3 represents (lxviii) 3-(2H-1,2,3-triazol-2-yl)pyridin-2-yl.

10. A pharmaceutical composition comprising the compound of formula (I) or a pharmaceutically acceptable salt thereof as claimed in claim 1 , in association with a pharmaceutically acceptable adjuvant, diluent or carrier, and optionally one or more other therapeutic agents.

11. The composition according to claim 10 , wherein the one or more other therapeutic agents are selected from carbamazepine, olanzapine, quetiapine, verapamil, lamotrigine, oxcarbazepine, risperidone, aripiprazole, ziprasidone and lithium.

12. The compound according to claim 1 , wherein the compound is selected from the group consisting of N-(4,4-Difluoro-2-{[5-(trifluoromethyl)pyrazin-2-yl]amino}cyclopentyl)-2-(2H-1,2,3 -triazol-2-yl)benzamide;

N-(4,4-Difluoro-2-{[5-(trifluoromethyl)pyrimidin-2-yl]amino}cyclopentyl)-2-(2H-1,2,3-triazol-2-yl)benzamide;

N-(4,4-Difluoro-2-{[5-(trifluoromethyl)pyridin-2-yl]amino}cyclopentyl)-2-(2H-1,2,3-triazol-2-yl)benzamide;

N-(4,4-Difluoro-2-{[5-(trifluoromethyl)pyridin-2-yl]amino}cyclopentyl)-2-(2H-1,2,3-triazol-2-yl)benzamide;

N-(4,4-Difluoro-2-{[5-(trifluoromethyl)pyrazin-2-yl]amino}cyclopentyl)-2-(2H-1,2,3-triazol-2-yl)benzamide;

N-[(1S,2S)-4,4-Difluoro-2-{[5-(trifluoromethoxy)pyridin-2-yl]amino}cyclopentyl]-2-(2H-1,2,3-triazol-2-yl)benzamide;

N-[(1S,2S)-4,4-Difluoro-2-{[3-fluoro-5-(trifluoromethyl)pyridin-2-yl]amino}cyclopentyl]-2-(2H-1,2,3 -triazol-2-yl)benzamide;

N-[(1S,2S)-2-{[5-(Difluoromethoxy)pyridin-2-yl]amino}-4,4-difluorocyclopentyl]-2-(2H-1,2,3-triazol-2-yl)benzamide;

enantiomers thereof and pharmaceutically acceptable salts of any of the foregoing.

13. A pharmaceutical composition comprising the compound according to claim 12 , in association with a pharmaceutically acceptable adjuvant, diluent or carrier, and optionally one or more other therapeutic agents.

14. The composition according to claim 13 , wherein the one or more other therapeutic agents are selected from carbamazepine, olanzapine, quetiapine, verapamil, lamotrigine, oxcarbazepine, risperidone, aripiprazole, ziprasidone and lithium.

15. The compound according to claim 1 , wherein R 1 represents 3-ethyl-5-(trifluoromethyl)pyrazin-2-yl and R 3 represents 3-(2H-1,2,3-triazol-2-yl)pyridin-2-yl.

16. The compound according to claim 1 , wherein the compound is N-[(1S,2S)-2-{[3 -ethyl-5-(trifluoromethyl)pyrazin-2-yl]amino}-4,4-difluorocyclopentyl]-3 -(2H-1,2,3-triazol-2-yl)picolinamide.

17. A pharmaceutical composition comprising the compound according to claim 15 , in association with a pharmaceutically acceptable adjuvant, diluent or carrier, and optionally one or more other therapeutic agents.

18. The composition according to claim 17 , wherein the one or more other therapeutic agents are selected from carbamazepine, olanzapine, quetiapine, verapamil, lamotrigine, oxcarbazepine, risperidone, aripiprazole, ziprasidone and lithium.