(2S)-N-[(2S)-3-(2-tert-butyl-3H-imidazol-4-yl)-1-[(2S)-2-carbamoylpyrrolidin-1-yl]-1-oxopropan-2-yl]-5-oxopyrrolidine-2-carboxamide (2S)-N-[(1S)-1-[(2-tert-butyl-3H-imidazol-4-yl)methyl]-2-[(2S)-2-carbamoylpyrrolidin-1-yl]-2-oxo-ethyl]-5-oxo-pyrrolidine-2-carboxamide (2S)-N-[(1S)-1-[(2-tert-butyl-3H-imidazol-4-yl)methyl]-2-[(2S)-2-carbamoyl-1-pyrrolidinyl]-2-oxoethyl]-5-oxo-2-pyrrolidinecarboxamide (2S)-N-[(1S)-1-[(2-tert-butyl-3H-imidazol-4-yl)methyl]-2-[(2S)-2-carbamoylpyrrolidin-1-yl]-2-keto-ethyl]-5-keto-pyrrolidine-2-carboxamide (2S)-N-[(2S)-1-[(2S)-2-aminocarbonylpyrrolidin-1-yl]-3-(2-tert-butyl-3H-imidazol-4-yl)-1-oxo-propan-2-yl]-5-oxo-pyrrolidine-2-carboxamide