2,5-Pyrrolidinedione, 3-amino-, (3S)-

(S)-Aspartimide is a byproduct formed during solid-phase peptide synthesis (SPPS) of aspartic acid-containing peptides.¹ Aspartimide is formed by cyclization of aspartic acid during Fmoc removal or peptide coupling.²

1. Ruczyński, J., Lewandowska, B., Mucha, P., et al. Problem of aspartimide formation in Fmoc-based solid-phase peptide synthesis using Dmab group to protect side chain of aspartic acid J. Pept. Sci. 14(3),335-341(2008).
2. Neumann, K., Farnung, J., Baldauf, S., et al. Prevention of aspartimide formation during peptide synthesis using cyanosulfurylides as carboxylic acid-protecting groups Nat. Commun. 11(1),982(2020).