(5S)-5-[(pyrrolidin-1-yl)carbonyl]pyrrolidin-2-one
(5S)-5-[(piperidin-1-yl)carbonyl]pyrrolidin-2-one
(2S)-5-oxopyrrolidine-2-carboxylic acid (R)-1-phenylethylamide
(2S)-5-oxopyrrolidine-2-carboxylic acid benzylamide
(S)-2-(1-piperidinylmethyl)pyrrolidine