2-oxo-1-pyrrolidine derivatives, processes for preparing them and their uses

1. A method of treating epilepsy in a mammal comprising administering to the mammal an effective amount of a compound having the structural formula (I)

or a geometric isomer, enantiomer, diastereomer, or pharmaceutically acceptable salt thereof, optionally together with a pharmaceutically acceptable carrier or diluent, wherein

R 1 is hydrogen;

R 2 is hydrogen;

R 3 is

(a) a substituted or unsubstituted heterocycle selected from the group consisting of imidazo[1,2-a]pyridin-3-yl, imidazo[1,2-a]pyrimidin-3-yl, imidazo[1,2-b][1,2,4]triazin-7-yl, imidazo[1,2-b]pyridazin-3-yl, 5,6,7,8-tetrahydroimidazo[1,2-b]pyridazin-3-yl, imidazo[2,1-b][1,3,4]thiadiazol-5-yl, imidazo[2,1-b][1,3]thiazol-5-yl, 1H-imidazol-4-yl, 1H-imidazol-5-yl, 1H-indo1-2-yl, 1H-indol-3-yl, isoxazol-4-yl, 1H-pyrazol-4-yl, 1H-pyrazol-5-yl, 1H-pyrazolo[1,5-a]pyrimidin-3-yl, 1H-pyrazolo[3,4-b]pyridin-3-yl, 1H-pyrrolo[2,3-b]pyridin-3-yl, 1H-pyrrolo[2,3-c]pyridin-2-yl, 1H-pyrrolo[2,3-c]pyridin-3-yl, 1H-pyrrolo[3,2-b]pyridin-3-yl, 1H-pyrrolo[3,2-c]pyridin-2-yl, 1H-pyrrolo[3,2-c]pyridin-3-yl, 1,3,4-thiadiazol-2-yl, 1,3-thiazol-5-yl, and indolizin-3-yl; or

(b) a substituted or unsubstituted heterocycle selected from the group consisting of 1H-1,2,3-benzotriazol-1-yl, 1H-imidazo[4,5-b]pyridin-1-yl, 3H-imidazo[4,5-b]pyridin-3-yl, 7H-imidazo[4,5-c]pyridazin-7-yl, 1H-indol-1-yl, 2,3-dihydro-1H-indol-lyl, 9H-purin-9-yl, 1H-pyrazolo[3,4-b]pyridin-1-yl, 2H-pyrazolo[3,4-b]pyridin-2-yl, 1H-pyrrolo[2,3-b]pyridin-1-yl, 1H-pyrrolo[3,2-b]pyridin-1-yl, 8H-isothiazolo[5,4-b]indol-8-yl, 1H-1,2,4-triazol-yl, and 1H-pyrrol-1-yl;

R 4 is C 1-12 alkyl optionally substituted by halogen or C 1-4 alkoxy; C 2-12 alkenyl optionally substituted by halogen; or C 2-12 alkynyl optionally substituted by halogen;

R 5 is hydrogen.

2. The method according to claim 1 , wherein the mammal is a human.

3. The method according to claim 2 , wherein R 4 is n-propyl; 2,2,2-trifluoroethyl; 2-chloro-2,2-difluoroethyl; 2-bromo-2,2-difluoroethyl; or 2,2-difluorovinyl.

4. The method according to claim 2 , wherein R 3 is a heterocycle selected from the group consisting of imidazo[1,2-a]pyrimidin-3-yl, imidazo[1,2-b][1,2,4]triazin-7-yl, imidazo[1,2-b]pyridazin-3-yl, 5,6,7,8-tetrahydroimidazo[1,2-b]pyridazin-3-yl, imidazo[2,1-b][1,3,4]thiadiazol-5-yl, imidazo[2,1-b][1,3]thiazol-5-yl, 1H-imidazol-4-yl, 1H-imidazol-5-yl, isoxazol-4-yl, 1H-pyrazol-4-yl, 1H-pyrazol-5-yl, 1H-pyrazolo[1,5-a]pyrimidin-3-yl, 1H-pyrazolo[3,4-b]pyridin-3-yl, 1H-pyrrolo[2,3-b]pyridin-3-yl, 1H-pyrrolo[2,3-c]pyridin-2-yl, 1H-pyrrolo[2,3-c]pyridin-3-yl, 1,3-thiazol-5-yl, and indolizin-3-yl.

5. The method according to claim 2 , wherein R 3 is imidazo[1,2-a]pyridin-3-yl.

6. The method according to claim 2 , wherein R 3 is a heterocycle selected from the group consisting of 3H-imidazo[4,5-b]pyridin-3-yl, 1H-indol-1-yl, 1H-pyrrolo[2,3-b]pyridin-1-yl, 1H-pyrrolo[3,2-b]pyridin-1-yl, and 1H-pyrrol-1-yl.

7. The method according to claim 2 , wherein R 1 , R 2 and R 5 are hydrogen;

R 4 is C 1-6 alkyl optionally substituted by halogen; C 2-6 alkenyl optionally substituted by halogen; or C 2-12 alkynyl optionally substituted by halogen; and

R 3 is a heterocycle selected from the group consisting of imidazo[1,2-b]pyridazin-3-yl, imidazo[2,1-b][1,3,4]thiadiazol-5-yl, imidazo[2,1-b][1,3]thiazol-5-yl, 1H-imidazol-4-yl, 1H-imidazol-5-yl, 1H-pyrazol-4-yl, 1H-pyrazolo [1,5-a]pyrimidin-3-yl, 1H-pyrrolo [2,3-b]pyridin-3-yl, and 1,3-thiazol-5-yl.

8. The method according to claim 2 , wherein

R 1 , R 2 and R 5 are hydrogen;

R 4 is C 1-6 alkyl optionally substituted by halogen; C 2-6 alkenyl optionally substituted by halogen; or C 2-12 alkynyl optionally substituted by halogen; and

R 3 is a heterocycle selected from the group consisting of 3H-imidazo[4,5-b]pyridin-3-yl, 1H-imidazo[4,5-b]pyridin-1-yl, and 1H-pyrrolo[2,3-b]pyridin-1-yl.

9. The method according to claim 2 wherein the compound is selected from the group consisting of:

1-(imidazo[1,2-a]pyridin-3-ylmethyl)-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(4-methylphenyl)imidazo[1,2-a]pyridin-3-yl]methyl 1-4-propylpyrrolidin-2-one;

1-{[2-(4-chlorophenyl)-6-methylimidazo[1,2-a]pyridin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(5-methylimidazo[1,2-a]pyridin-3-yl)methyl]-4-phenylpyrrolidin-2-one;

1-(imidazo[1,2-a]pyridin-3-ylmethyl)-4-phenylpyrrolidin-2-one;

1-[(6-methylimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromoimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(8-methylimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-iodoimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[8-chloro-6-(trifluoromethyl)imidazo[1,2-a]pyridin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(7-methylimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6,8-dibromoimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6,8-dichloroimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-chloroimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloroimidazo[1,2-a]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-cydopropyl-6-fluoroimidazo[1,2-a]pyridin-3-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-chloro-2-cyclopropylimidazo[1,2-a]pyridin-3-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-(imidazo[1,2-a]pyrimidin-3-ylmethyl)-4-propylpyrrolidin-2-one;

1-{[2-(4-chlorophenyl)imidazo[1,2-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-(imidazo[1,2-a]pyrimidin-3-ylmethyl)-4-phenylpyrrolidin-2-one;

1-[(6-chloroimidazo[1,2-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(6-phenylimidazo[1,2-b][1,2,4]triazin-7-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(4-methylphenyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(4-chlorophenyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(6-chloroimidazo[1,2-b]pyridazin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-chloroimidazo[1,2-b]pyridazin-3-yl)methyl]-4-phenylpyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,3,5-trifluorophenyl)pyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-phenylpyrrolidin-2-one;

1-{[6-methoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(6-chloro-2-cyclopropylimidazo[1,2-b]pyridazin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[6-isopropoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-(benzyloxy)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-cyclopropyl-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-(dimethylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-methoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2-chloro-2,2-difluoroethyl)-1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[6-(methylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-hydroxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-(methylthio)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

4-(2-bromo-2,2-difluoroethyl)-1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[6-(methylsulfonyl)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-(methylsulfinyl)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2,2-trifluoroethyl)pyrrolidin-2-one;

1-[(6-chloro-2-cyclobutylimidazo[1,2-b]pyridazin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[6-chloro-2-(4-methylphenyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[6-amino-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-(ethylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-propylpyrrolidin-2-one;

4-propyl-1-{[6-(propylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2-bromo-2,2-difluoroethyl)-1-{[6-(propylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-(propylamino)-2-trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-methoxy-2-(4-methylphenyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-propyl-1-{[6-pyrrolidin-1-yl-2-trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2-bromo-2,2-difluoroethyl)-1-{[6-methoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[6-(cyclopropylamino)-2-trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-chloro-2-cyclopropylimidazo[1,2-b]pyridazin-3-yl)methyl]-442,2-difluorovinyl)pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-(isopropylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[2-cyclopropyl-6-(propylamino)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-({2-cyclopropyl-6-[(2-fluoroethyl)amino]imidazo [1,2-b]pyridazin-3-yl}methyl)-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-({2-cyclopropyl-6-[(2,2-difluoroethyl)amino]imidazo [1,2-b]pyridazin-3-yl}methyl)-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-({2-cyclopropyl-6-[(2,2,2-trifluoroethyl)amino]imidazo [1,2-b]pyridazin-3-yl}methyl)-4-(2,2-difluorovinyl)pyrrolidin-2-one;

4-(2,2-difluoroethyl)-1-{[2-(trifluoromethyl)imidazo [1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[2-cyclopropyl-6-(cyclopropylamino)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-chloro-2-cyclobutylimidazo[1,2-b]pyridazin-3-yl)methyl]-442,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-chloro-2-cyclopropylimidazo[1,2-b]pyridazin-3-yl)methyl]-4-(3-chloro-4-fluorophenyl)pyrrolidin-2-one;

1-{[6-(butylamino)-2-(trifluoromethyl)imidazo [1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[6-(cyclobutylamino)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(2-cyclopropyl-6-methoxyimidazo[1,2-b]pyridazin-3-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-ethoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-isopropoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-{[6-(cyclopropylmethoxy)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[6-(cyclobutylmethoxy)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[6-(cyclopropyloxy)-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-propoxy-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

3-{[4-(2,2-difluorovinyl)-2-oxopyrrolidin-1-yl]methyl}-2-(trifluoromethyl)imidazo[1,2-b]pyridazine-6-carbonitrile;

4-(2,2-difluorovinyl)-1-{[6-thien-3-yl-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-phenyl-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-methyl-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-{[6-pyridin-3-yl-2-(trifluoromethyl)imidazo[1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

4-propyl-1- {[2-(trifluoromethyl)-5 ,6,7,8-tetrahydroimidazo [1,2-b]pyridazin-3-yl]methyl}pyrrolidin-2-one;

1-[(6-methylimidazo[2,1-b][1 ,3 ,4]thiadiazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[6-(4-methylphenyl)imidazo[2,1-b][1,3,4]thiadiazol-5-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(2-cyclopropyl-6-phenylimidazo[2,1-b][1,3,4]thiadiazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-methylimidazo[2,1-b][1,3 ]thiazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-chloroimidazo[2,1-b][1,3 ]thiazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2,6-dichloroimidazo[2,1-b][1,3 ]thiazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[1-(1H-imidazol-4-yl)propyl]pyrrolidin-2-one;

1-[(5-methyl- 1H-imidazol-4-yl)methyl]pyrrolidin-2-one;

1-[(2-methyl- 1H-imidazol-4-yl)methyl]pyrrolidin-2-one;

1-(1H-imidazol-4-ylmethyl)-4-propylpyrrolidin-2-one;

1-({1-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-imidazol-4-yl}methyl)-4-propylpyrrolidin-2-one;

1-[(5-chloro-1H-imidazol-4-yl)methyl]-4(2,3,5-trifluorophenyl)pyrrolidin-2-one;

1-[(5-bromo-1H-imidazol-4-yl)methyl]-4(2,3,5-trifluorophenyl)pyrrolidin-2-one;

1-(1H-imidazol-5-ylmethyl)pyrrolidin-2-one;

1-[(1-methyl- 1H-imidazol-5-yl)methyl]pyrrolidin-2-one;

1-methyl-5-[(2-oxopyrrolidin-1-yl)methyl]-1H-imidazole-4-carbonitrile;

1-(1H-imidazol-5-ylmethyl)-4-phenylpyrrolidin-2-one;

1-[(1-methyl- 1H-imidazol-5-yl)methyl]-4-phenylpyrrolidin-2-one;

1-[(4-methoxy-1-methyl- 1H-imidazol-5-yl)methyl]pyrrolidin-2-one;

1-[(1-methyl- 1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-methyl-5-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-imidazole-4-carbonitrile;

1-methyl-5-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-imidazole-4-carboxamide;

N-benzyl-2-{5-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]- 1H-imidazol-1-yl}acetamide;

1-methyl-5-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-imidazole-2-carbonitrile;

1-[(4-chloro-1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-methyl-5-{[2-oxo-4-(2,3,5-trifluorophenyl)pyrrolidin-1-yl]methyl}-1H-imidazole-4-carbonitrile;

1-[(4-bromo-1-methyl-1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2,4-dichloro-1-methyl-1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

benzyl 1-methyl-5-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]- 1H-imidazol-2-ylcarbamate;

1-[(4-chloro-1-methyl-1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-bromo-1-methyl-1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1-methyl-1H-imidazol-5-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2,4-dichloro-1H-imidazol-5-yl)methyl]-442,3 ,5-trifluorophenyl)pyrrolidin-2-one;

1-[(2,4-dichloro-1-methyl-1H-imidazol-5-yl)methyl]-442,3 ,5-trifluorophenyl)pyrrolidin-2-one;

1-[(2-chloro-1-methyl-1H-imidazol-5-yl)methyl]-442,3 ,5-trifluorophenyl)pyrrolidin-2-one;

1-[(4-bromo-1-methyl-1H-imidazol-5-yl)methyl]-4-(2,3 ,5-trifluorophenyl)pyrrolidin-2-one;

1-[(4-chloro-1-methyl-1H-imidazol-5-yl)methyl]-442,3 ,5-trifluorophenyl)pyrrolidin-2-one;

1-(1H-indol-2-ylmethyl)-4-propylpyrrolidin-2-one;

1-(1H-indo1-3-ylmethyl)-4-propylpyrrolidin-2-one;

3-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-indole-5-carbonitrile;

1-[(2-methyl- 1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(7-methoxy-1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-nitro-1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

4-propyl-1-{[6-(trifluoromethyl)-1H-indo1-3-yl]methyl}pyrrolidin-2-one;

1-[(5-nitro-1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(7-fluoro-1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-chloro-2-methyl-1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[1H-indo1-3-yl(phenyl)methyl]-4-propylpyrrolidin-2-one;

1-[1-(1H-indol-3-yl)propyl]-4-propylpyrrolidin-2-one;

1-[2-furyl(1H-indo1-3-yl)methyl]-4-propylpyrrolidin-2-one;

3-[(2-oxo-4-propylpyrrolidin-1-yl)(phenyl)methyl]-1H-indole-5-carbonitrile;

1-(isoxazol-4-ylmethyl)-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-methylpyrazolo [1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-methylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-thien-2-ylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

4-propyl-1-[(2-thien-2-ylpyrazolo [1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

1-[(6-bromo-2-cyclopropylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-tert-butylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-tert-butyl-6-cyclopropylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[2-(2-furyl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(2-methyl-6-thien-2-ylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-methyl-6-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[2-methyl-6-(1H-pyrrol-2-yl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-({6-[(1E)-hex-1-enyl]-2-methylpyrazolo[1,5-a]pyrimidin-3-yl}methyl)-4-propylpyrrolidin-2-one;

1-[(6-chloro-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[2-methyl-6-(phenylethynyl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-hydroxy-2-methylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-methyl-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-[(2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

1-[(6-methoxy-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-chloropyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-[(5,6-dimethyl-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-[(6-fluoro-5-methyl-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

1-[(5-methoxypyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[2-(4-bromophenyl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[2-(4-fluorophenyl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-[(6-methyl-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-[(5-methyl-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

4-(2,2-difluorovinyl)-1-[(2-thien-2-ylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]pyrrolidin-2-one;

1-{[2-(4-chlorophenyl)-6-methylpyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[2-(4-chlorophenyl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-chloro-2-phenylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4(2,2-difluorovinyl)pyrrolidin-2-one;

1-{[6-chloro-2-(4-chlorophenyl)pyrazolo[1,5-a]pyrimidin-3-yl]methyl}-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(2-cyclopropyl-5-methylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(5-chloro-2-cyclopropylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(5-chloro-2,6-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)methyl]-4(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(5-bromo-1H-pyrazolo[3,4-b]pyridin-3-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[2,3-b]pyridin-3-ylmethyl)pyrrolidin-2-one;

1-[(2-isopropyl-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-phenyl-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

4-propyl-1-[(2-propyl-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]pyrrolidin-2-one;

1-[(6-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(1-benzoyl-6-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-phenyl-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-bromo-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(7-oxido-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[2,3-c]pyridin-2-ylmethyl)pyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[2,3-c]pyridin-3-ylmethyl)pyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[3,2-b]pyridin-3-ylmethyl)pyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[3,2-c]pyridin-2-ylmethyl)pyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[3,2-c]pyridin-3-ylmethyl)pyrrolidin-2-one;

4-propyl-1-(1,3,4-thiadiazol-2-ylmethyl)pyrrolidin-2-one;

1-[(2-amino-1,3-thiazol-5-yl)methyl]pyrrolidin-2-one;

1-(1,3-thiazol-5-ylmethyl)pyrrolidin-2-one;

1-[(2-chloro-1,3-thiazol-5-yl)methyl]-4(2,3,5-trifluorophenyl)pyrrolidin-2-one;

1-{[2-(dimethylamino)-1,3-thiazol-5-yl]methyl}-4(2,3,5-trifluorophenyl)pyrrolidin-2-one;

1-{[2-(methylamino)-1,3-thiazol-5-yl]methyl}-4-(2,3,5-trifluorophenyl)pyrrolidin-2-one;

1-[(2-pyrrolidin-1-yl-1,3-thiazol-5-yl)methyl]-4(2,3,5-trifluorophenyl)pyrrolidin-2-one;

5-{[2-oxo-4-(2,3,5-trifluorophenyl)pyrrolidin-1-yl]methyl}-1,3-thiazol-2(3H)-one;

1-[(2-fluoroindolizin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-(1H-1,2,3-benzotriazol-1-ylmethyl)-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-chloro-1H-imidazo[4,5-b]pyridin-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-phenyl-1H-imidazo[4,5-b]pyridin-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-(3H-imidazo[4,5-b]pyridin-3-ylmethyl)-4-propylpyrrolidin-2-one;

1-[(6-bromo-3H-imidazo[4,5-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-chloro-3H-imidazo[4,5-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-phenyl-3H-imidazo[4,5-b]pyridin-3-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-bromo-2-cyclopropyl-3H-imidazo[4,5-b]pyridin-3-yl)methyl]-4(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(3-chloro-7H-imidazo[4,5-c]pyridazin-7-1)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-methyl- 1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-methyl- 1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-phenyl-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-fluoro-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-bromo-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-chloro-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-(2,3-dihydro-1H-indol-1-ylmethyl)-4-propylpyrrolidin-2-one;

1-[(5-fluoro-2-phenyl-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-indole-2-carbonitrile;

1-[(2-bromo-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2,5-dichloro-1H-indol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(6-amino-9H-purin-9-yl)methyl]-4-propylpyrrolidin-2-one;

4-propyl-1-(9H-purin-9-ylmethyl)pyrrolidin-2-one;

1-{[6-(cyclopropylamino)-9H-purin-9-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[6-(benzylamino)-9H-purin-9-yl]methyl}-4-propylpyrrolidin-2-one;

4-propyl-1-{[6-(propylamino)-9H-purin-9-yl]methyl}pyrrolidin-2-one;

1-({6-[(cyclopropylmethyl)amino]-9Hpurin-9-yl}methyl-4-propylpyrrolidin-2-one;

4-propyl-1-[(6-pyrrolidin-1-yl-9H-purin-9-yl)methyl]pyrrolidin-2-one;

1-[(5-bromo-3-phenyl-1H-pyrazolo[3,4-b]pyridin-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-bromo-2H-pyrazolo[3,4-b]pyridin-2-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-bromo-3-phenyl-2H-pyrazolo[3,4-b]pyridin-2-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-pyrroIo[2,3-b]pyridin-1-yl)methyl]-4-propylpyrrolidin-2-one;

4-propyl-1-(1H-pyrrolo[3,2-b]pyridin-1-ylmethyl)pyrrolidin-2-one;

1-(8H-isothiazolo[5,4-b]indo1-8-ylmethyl)-4-propylpyrrolidin-2-one;

1-[(2,5-dichloro-1H-pyrrol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-pyrrol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-b enzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-benzimidazol-1-yl)methyl]-4-phenylpyrrolidin-2-one;

2-chloro-1-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-benzimidazole-5-carbonitrile;

2-chloro-1-[(2-oxo-4-propylpyrrolidin-1-yl)methyl]-1H-benzimidazole-6-carbonitrile;

4-propyl-1-[(2,5 ,6-trichloro-1H-benzimidazol-1-yl)methyl]pyrrolidin-2-one;

1-[(2-chloro-6-methoxy-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-5-methoxy-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-6-nitro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-5-nitro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-6-methyl-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-benzimidazol-1-yl)methyl]-4-(2,2-difluorovinyl)pyrrolidin-2-one;

1-[(6-bromo-2-chloro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(5-bromo-2-chloro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-6-fluoro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-5-fluoro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2,6-dichloro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2,5-dichloro-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-{[2-chloro-6-(trifluoromethyl)-1H-benzimidazol-1-yl]methyl}-4-propylpyrrolidin-2-one;

1-{[2-chloro-5-(trifluoromethyl)-1H-benzimidazol-1-yl]methyl}-4-propylpyrrolidin-2-one;

1-[(2-chloro-1H-benzimidazol-1-yl)methyl]pyrrolidin-2-one;

1-[(2-chloro-6-hydroxy-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one;

1-[(2-chloro-5-hydroxy-1H-benzimidazol-1-yl)methyl]-4-propylpyrrolidin-2-one; and

a geometric isomer, an enantiomer, a diastereomer, or a pharmaceutically acceptable salt thereof.

10. A method of treating epilepsy in a mammal, the method comprising administering to the mammal a therapeutically effective amount of a compound of formula (I),

or a geometric isomer, enantiomer, diastereomer, or pharmaceutically acceptable salt thereof, optionally together with a pharmaceutically acceptable carrier or diluent, wherein

R 1 , R 2 and R 5 are hydrogen,

R 4 is a C 1-6 alkyl optionally substituted by halogen, a C 2-6 alkenyl optionally substituted by halogen, or C 2-12 alkynyl optionally substituted by halogen,

R 3 is selected from the group consisting of;

imidazo[1,2-b]pyridazin-3-yl;

imidazo[2,1-1)][1,3,4]thiadiazol-5-y 1 ;

imidazo[2,1-b][1,3]thiazol-5-yl;

1H-imidazol-4-yl;

1H-imidazol-5-yl;

1H-pyrazol-4-yl;

1H-pyrazolo[1,5-a]pyrimidin-3-yl;

1H-pyrrolo[2,3-b]pyridin-3-yl;

1,3-thiazol-5-yl;

and optionally substituted by methyl, n-propyl, trifluoromethyl, cyclopropyl, bromine, chlorine, fluorine, iodine, methoxy, ethoxy, propoxy, isopropoxy, cyclopropyloxy, cyclopropylmethoxy, cyclobutylmethoxy, amino, methylamino, cyclopropylamino, cyclobutylamino, 1-pyrrolidinyl, cyano, phenyl, benzyl or 3-thienyl,

and wherein the disease or condition is selected from the group consisting of epilepsy, dyskinesia induced by dopamine replacement therapy, chronic pain, and neuropathic pain.

11. The method according to claim 10 , wherein the mammal is a human.

12. The method according to claim 2 , wherein R 1 , R 2 and R 5 are hydrogen,

R 4 is a C 1 - 6 alkyl optionally substituted by halogen, a C 2-6 alkenyl optionally substituted by halogen, or C 2-12 alkynyl optionally substituted by halogen, and

R 3 is

3H-imidazo[4,5-b]pyridin-3-yl,

1H pyrrolo[3,2-b]pyridin-l-yl,

1H-pyrrol-1-yl, or

2-chloro-1H-benzimidazol-1-yl,

optionally substituted by trifluoromethyl, cyclopropyl, bromine, chlorine, fluorine, methoxy or cyano.

13. The method according to claim 2 , wherein the heterocycles of R 3 are optionally substituted with methyl, n-propyl, trifluoromethyl, cyclopropyl, bromine, chlorine, fluorine, iodine, methoxy, ethoxy, propoxy, isopropoxy, cyclopropyloxy, cyclopropylmethoxy, cyclobutylmethoxy, amino, methylamino, cyclopropylamino, cyclobutylamino, 1-pyrrolidinyl, cyano, phenyl, benzyl or 3-thienyl.

14. The method according to claim 2 , wherein R 3 is substituted or unsubstituted imidazo[2,1-b][1,3,4]thiadiazol-5-yl.

15. The method according to claim 2 , wherein the R 3 heterocycle is optionally substituted with from 1to 5substituents selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, cycloalkyl, heterocycloalkyl, amino, aryl, heteroaryl, alkoxy, halogen, cyano, hydroxy, mercapto, nitro, amido, sulfanyl, sulfinyl, and sulfonyl.