1-benzyl-4-(R)-<1-(S)-ethyl>-2-pyrrolidone

4-acetyl-1-benzyl-2-pyrrolidinone

ethyl [L-(trans)]-4-[(t-butoxycarbonyl)amino]-2-pentenoate

ethyl (S)-4-[(tert-butoxycarbonyl)amino]-3-oxopentanoate

1-benzyl-4-(1-hydroxyiminoethyl)-2-pyrrolidone