(2R)-2-cyclohexyl-2-[(3S,4S)-3-[[4-[3-(3-fluoro-4-methylphenyl)propyl]piperidin-1-yl]methyl]-4-phenylpyrrolidin-1-yl]acetic acid;(2R)-2-cyclohexyl-2-[(4S)-3-[[4-[3-(4-fluorophenyl)propyl]-4-hydroxypiperidin-1-yl]methyl]-4-phenylpyrrolidin-1-yl]acetic acid;2-[(3S,4S)-3-[[4-[3-(3,4-difluorophenyl)propyl]-4-methylpiperidin-1-yl]methyl]-4-phenylpyrrolidin-1-yl]-4-methylpentanoic acid;2-[(3S,4S)-3-[[4-[3-(3,4-difluorophenyl)propyl]-4-methylpiperidin-1-yl]methyl]-4-phenylpyrrolidin-1-yl]pentanoic acid;(3R)-3-[(3S,4S)-3-[[4-[3-(4-fluorophenyl)propyl]-4-hydroxypiperidin-1-yl]methyl]-4-phenylpyrrolidin-1-yl]-4-methylpentan-2-one