4-[4-(2-cyclopentyloxy-5-methylsulfonylbenzoyl)piperazin-1-yl]-3-fluorobenzonitrile 4-[4-[2-(cyclopentoxy)-5-methylsulfonyl-benzoyl]piperazin-1-yl]-3-fluoro-benzonitrile 4-[4-[[2-(cyclopentoxy)-5-methylsulfonylphenyl]-oxomethyl]-1-piperazinyl]-3-fluorobenzonitrile 4-[4-[2-(cyclopentoxy)-5-mesyl-benzoyl]piperazin-1-yl]-3-fluoro-benzonitrile 4-[4-(2-cyclopentyloxy-5-methylsulfonyl-phenyl)carbonylpiperazin-1-yl]-3-fluoro-benzonitrile