Imidazoisoindole neuropeptide S receptor antagonists

1. A compound of the formula:

wherein:

R 1 is hydrogen or C 1-6 alkyl;

R 2 is hydrogen or C 1-6 alkyl;

R 3a is selected from the group consisting of:

(1) hydrogen,

(2) halogen,

(3) —CN, and

(4) C 1-6 alkyl;

R 4 is selected from the group consisting of:

(1) —CH 2 CH 2 —(C═O)-heterocycle, where the heterocycle is unsubstituted or substituted with one or more substituents selected from R 13 , and

(2) —CH 2 CH 2 —(C═O)—NR 15 R 16 , where R 15 and R 16 are independently selected from hydrogen and —C 1-6 alkyl, which is unsubstituted or substituted with phenyl;

R 13 is selected from the group consisting of:

(1) halogen,

(2) hydroxyl,

(3) —(C═O) m —O n —C 1-6 alkyl, where m is 0 or 1, n is 0 or 1 (wherein if m is 0 or n is 0, a bond is present) and where the alkyl is unsubstituted or substituted with one or more substituents selected from R 14 ,

(4) —O n —(C 1-3 )perfluoroalkyl,

(5) —(C═O) m —O n C 3-6 cycloalkyl, where the cycloalkyl is unsubstituted or substituted with one or more substituents selected from R 14 ,

(6) —(C═O) m —C 2-4 alkenyl, where the alkenyl is unsubstituted or substituted with one or more substituents selected from R 14 ,

(7) —(C═O) m —C 2-4 alkynyl, where the alkenyl is unsubstituted or substituted with one or more substituents selected from R 14 ,

(8) —(C═O) m —O n -phenyl or —(C═O) m —O n -napthyl, where the phenyl or is unsubstituted or substituted with one or more substituents selected from R 14 ,

(9) —(C═O) m —O n -heterocycle, where the heterocycle is unsubstituted or substituted with one or more substituents selected from R 14 ,

(10) —(C═O) m —NR 15 R 16 ,

(11) —S(O) 2 —NR 15 R 16 ,

(12) —S(O) q —R 17 , where q is 0, 1 or 2 and where R 17 is —C 1-6 alkyl, which is unsubstituted or substituted with phenyl;

(13) —CO 2 H

(14) —CN, and

(15) —NO 2 ;

R 14 is selected from the group consisting of:

(1) hydroxyl,

(2) halogen,

(3) C 1-6 alkyl,

(4) —C 3-6 cycloalkyl,

(5) —O—C 1-6 alkyl,

(6) —O(C═O)—C 1-6 alkyl,

(7) —NH—C 1-6 alkyl,

(8) phenyl,

(9) heterocycle,

(10) —CO 2 H, and

(11) —CN;

or a pharmaceutically acceptable salt thereof.

2. The compound of claim 1 wherein R 1 is hydrogen and R 2 is hydrogen.

3. A compound which is selected from the group consisting of:

5-(4-bromophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-2-methyl-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-3-methyl-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-2-ethyl-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-3-ethyl-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-2-methyl-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-3-methyl-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindol-7-ol;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-2-(trifluoromethyl)-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-2-(trifluoromethyl)-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-6-methoxy-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-8-methoxy-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-9-methoxy-5H-imidazo[2,1-a]isoindole;

3-[5-(4-chlorophenyl)-6-methoxy-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-diethylpropanamide;

2-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-diethylacetamide;

5-(4-bromophenyl)-5-[2-(4,4-dimethylpiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{2-oxo-2-[4-(1H-pyrazol-4-yl)piperidin-1-yl]ethyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-oxo-2-(4-phenylpiperidin-1-yl)ethyl]-5H-imidazo[2,1-a]isoindole;

5-{2-[(1s,4s)-7-azabicyclo[2.2.1]hept-7-yl]-2-oxoethyl}-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(hexahydrofuro[3,2-b]pyridin-4(2H)-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(3,3-difluoropyrrolidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(4,4-difluoropiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(4-fluoropiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-oxo-2-(4-pyridin-4-ylpiperidin-1-yl)ethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(2-ethylpiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(3-methylpiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(3,3-dimethylpiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(3,4-dihydroisoquinolin-2(1H)-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-[2-(2-benzylpyrrolidin-1-yl)-2-oxoethyl]-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

5-[2-(2-azaspiro[4.4]non-2-yl)-2-oxoethyl]-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-oxo-2-(2-phenylpyrrolidin-1-yl)ethyl]-5H-imidazo[2,1-a]isoindole;

2-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-(3-hydroxy-1,1-dimethylbutyl)acetamide;

2-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-pyridin-2-ylacetamide;

2-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-cyclohexyl-N-methylacetamide;

2-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethyl-N-(1-methylethyl)acetamide;

5-(4-bromophenyl)-5-[2-(octahydroquinolin-1(2H)-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[2-(3,5-dimethylpiperidin-1-yl)-2-oxoethyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-(2-oxo-2-pyrrolidin-1-ylethyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-(3-oxo-3-piperidin-1-ylpropyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-(3-oxo-3-pyrrolidin-1-ylpropyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-cyclopropylpropanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-diethylpropanamide;

5-(4-bromophenyl)-5-[3-(3,3-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[4-(1H-pyrazol-4-yl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(4-phenylpiperidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(4-pyridin-4-ylpiperidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2-ethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(2-propylpiperidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3-methylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3,5-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-cyclohexyl-N-(1-methylethyl)propanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-cyclohexyl-N-methylpropanamide;

5-(3-azepan-1-yl-3-oxopropyl)-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylethyl)propanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(2-methylpropyl)propanamide;

5-(4-bromophenyl)-5-[3-(4,4-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(1,4-dioxa-8-azaspiro[4.5]dec-8-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

1-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidine-3-carboxamide;

5-[3-(1,4′-bipiperidin-1′-yl)-3-oxopropyl]-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(4-pyrrolidin-1-ylpiperidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[3-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(octahydro-2H-pyrido[1,2-a]pyrazin-2-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-[4-(1-morpholin-4-ylethyl)piperidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[2-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethyl-N-(tetrahydrofuran-2-ylmethyl)propanamide;

5-(4-bromophenyl)-5-[3-oxo-3-(3-phenylpiperidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[4-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

(1-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidin-4-yl)(pyridin-3-yl)methanol;

5-(4-bromophenyl)-5-{3-[3-(morpholin-4-ylmethyl)piperidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-[4-(morpholin-4-ylmethyl)piperidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3-methoxypiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(1,4-dioxa-7-azaspiro[4.5]dec-7-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3-fluoropiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

6-(1-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidin-4-yl)pyridin-2(1H)-one;

5-(4-bromophenyl)-5-[3-(4-cyclopropylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2,6-dimethylmorpholin-4-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(2-phenylmorpholin-4-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(2-pyridin-3-ylmorpholin-4-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3,3-difluoropiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-[(1S,4S)-2-oxa-5-azabicyclo[2.2.1]hept-5-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-(3-morpholin-4-yl-3-oxopropyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(4,4-difluoropiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2-methylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-[2-(methoxymethyl)pyrrolidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[3-(trifluoromethyl)pyrrolidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3-methylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(3,3-difluoropyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(2-phenylpyrrolidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-oxo-3-(3-phenylpyrrolidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(4-fluoropiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(4,4-dimethyl-1,3-oxazolidin-3-yl)-3-oxopropyl]-5H-imidazo[2,1-]isoindole;

5-(4-bromophenyl)-5-[3-(2-methylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[3-(2,6-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-[3-(2-azabicyclo[2.2.1]hept-2-yl)-3-oxopropyl]-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-tert-butyl-N-methylpropanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-tert-butyl-N-ethylpropanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-tert-butyl-N-(2-methoxyethyl)propanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-(dicyclopropylmethyl)propanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-dimethylpropanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-dipropylpropanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(2-methoxyethyl)propanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylpropyl)propanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethyl-N-(1-methylethyl)propanamide;

5-{3-[(1s,4s)-7-azabicyclo[2.2.1]hept-7-yl]-3-oxopropyl}-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

5-[3-(8-azabicyclo[3.2.1]oct-8-yl)-3-oxopropyl]-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-diethylpropanamide;

5-(4-chlorophenyl)-5-[3-(3,3-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2-ethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-{3-oxo-3-[4-(thiophen-2-ylcarbonyl)piperazin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(3-methylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(3,5-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(3-azepan-1-yl-3-oxopropyl)-5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylethyl)propanamide;

1-{3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidine-3-carboxamide;

5-(4-chlorophenyl)-5-{3-oxo-3-[3-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-{3-oxo-3-[2-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2-methylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-{3-[2-(methoxymethyl)pyrrolidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-(3-oxo-3-piperidin-1-ylpropyl)-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(3,4-dihydro-1,5-naphthyridin-1(2H)-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,3-dihydro-1H-pyrrolo[2,3-b]pyridin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,3-dihydro-1H-pyrrolo[2,3-c]pyridin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-methyl-N-pyridin-4-ylpropanamide;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-methyl-N-pyridin-2-ylpropanamide;

5-(4-chlorophenyl)-5-[3-(4,4-dimethyl-1,3-oxazolidin-3-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2-methylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,6-dimethylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-[3-(2-azabicyclo[2.2.1]hept-2-yl)-3-oxopropyl]-5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindole;

N-tert-butyl-3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-methylpropanamide;

N-tert-butyl-3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethylpropanamide;

N-tert-butyl-3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-(2-methoxyethyl)-propanamide;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-dimethylpropanamide;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-dipropylpropanamide;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(2-methoxyethyl)propanamide;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylpropyl)propanamide;

3-[5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethyl-N-(1-methylethyl)propanamide;

5-(3-azetidin-1-yl-3-oxopropyl)-5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindole;

5-{3-[(1s,4s)-7-azabicyclo[2.2.1]hept-7-yl]-3-oxopropyl}-5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindole;

5-[3-(8-azabicyclo[3.2.1]oct-8-yl)-3-oxopropyl]-5-(4-chlorophenyl)-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-7-methoxy-5H-imidazo[2,1-a]isoindole;

5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

N,N-diethyl-3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanamide;

5-[3-(3,3-dimethylpiperidin-1-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

5-[3-(2-ethylpiperidin-1-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-{3-oxo-3-[4-(thiophen-2-ylcarbonyl)piperazin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-[3-(3-methylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-[3-(3,5-dimethylpiperidin-1-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

5-(3-azepan-1-yl-3-oxopropyl)-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylethyl)propanamide;

1-{3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidine-3-carboxamide;

5-(4-fluorophenyl)-5-{3-oxo-3-[3-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-{3-oxo-3-[2-(trifluoromethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-[3-(2-methylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-{3-[2-(methoxymethyl)pyrrolidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-(3-oxo-3-piperidin-1-ylpropyl)-5H-imidazo[2,1-a]isoindole;

5-(4-fluorophenyl)-5-[3-(2-methylpiperidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindole;

5-[3-(2,6-dimethylpiperidin-1-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

5-[3-(2-azabicyclo[2.2.1]hept-2-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

N-tert-butyl-3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-methylpropanamide;

N-tert-butyl-N-ethyl-3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanamide;

N-tert-butyl-3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-(2-methoxyethyl)propanamide;

3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-dipropylpropanamide;

3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylpropyl)propanamide;

N-ethyl-3-[5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-(1-methylethyl)propanamide;

5-{3-[(1s,4s)-7-azabicyclo[2.2.1]hept-7-yl]-3-oxopropyl}-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

5-[3-(8-azabicyclo[3.2.1]oct-8-yl)-3-oxopropyl]-5-(4-fluorophenyl)-5H-imidazo[2,1-a]isoindole;

4-{5-[3-(2,5-dimethylpyrrolidin-1-yl)-3-oxopropyl]-5H-imidazo[2,1-a]isoindol-5-yl}benzonitrile;

5-(4-bromophenyl)-5-{3-oxo-3-[4-(pyrrolidin-1-ylmethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-chlorophenyl)-7-methoxy-5-{3-oxo-3-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-[4-(2,5-dimethylpyrrolidin-1-yl)-4-oxobutyl]-5H-imidazo[2,1-a]isoindole;

4-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-bis(1-methylethyl)butanamide;

4-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethyl-N-methylbutanamide;

5-(4-bromophenyl)-5-(4-oxo-4-piperidin-1-ylbutyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{4-oxo-4-[4-(1-pyrrolidin-1-ylethyl)piperidin-1-yl]butyl}-5H-imidazo[2,1-a]isoindole;

(1-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidin-4-yl)methanol;

5-(4-bromophenyl)-5-{3-[(2R,5R)-2,5-dimethylpyrrolidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-methyl-N-(1-methylcyclopentyl)-propanamide;

5-(4-bromophenyl)-5-[3-oxo-3-(2-propylpyrrolidin-1-yl)propyl]-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-methyl-N-(1-methylpiperidin-4-yl)propanamide;

N-benzyl-3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethylpropanamide;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-(2,4-dimethylcyclopentyl)-N-methylpropanamide;

(1-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperidin-4-yl)(pyridin-2-yl)methanol;

1′-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}-3H-spiro[2-benzofuran-1,4′-piperidin]-3-one;

5-(4-bromophenyl)-5-{3-[4-(5-methyl-1,3,4-oxadiazol-2-yl)piperidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-(3-{3-[(2-methyl-1H-imidazol-1-yl)methyl]piperidin-1-yl}-3-oxopropyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-[4-(3-methyl-1H-pyrazol-5-yl)piperidin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[4-(1H-pyrazol-1-ylmethyl)piperidin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-[4-(cyclopentylmethyl)piperazin-1-yl]-3-oxopropyl}-5H-imidazo[2,1-a]isoindole;

2-(4-{3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]propanoyl}piperazin-1-yl)cyclohexanol;

5-{3-[4-(1-azabicyclo[2.2.2]oct-3-yl)piperazin-1-yl]-3-oxopropyl}-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-{3-oxo-3-[4-(2-pyrrolidin-1-ylethyl)piperazin-1-yl]propyl}-5H-imidazo[2,1-a]isoindole;

5-(4-bromophenyl)-5-(3-{4-[(2-methyl-1,3-thiazol-4-yl)methyl]piperazin-1-yl}-3-oxopropyl)-5H-imidazo[2,1-a]isoindole;

5-[3-(4-benzylpiperazin-1-yl)-3-oxopropyl]-5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindole;

3-[5-(4-bromophenyl)-5H-imidazo[2,1-a]isoindol-5-yl]-N-ethyl-N-(2-methoxyethyl)propanamide;

3-[5-(4-chlorophenyl)-7-methoxy-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-diethylpropanamide; and

3-[5-(4-chlorophenyl)-7-methoxy-5H-imidazo[2,1-a]isoindol-5-yl]-N,N-dipropylpropanamide;

or a pharmaceutically acceptable salt thereof.

4. A pharmaceutical composition which comprises an inert carrier and a compound of claim 1 or a pharmaceutically acceptable salt thereof.