Cysteine Pseudoprolines for Thiol Protection and Peptide Macrocyclization Enhancement in Fmoc-Based Solid-Phase Peptide Synthesis

Contrary to other studies, here we describe cysteine (Cys) pseudoproline-containing peptides with short deprotection times in TFA. The deprotection times fell in the same range as other protecting groups commonly used in SPPS (e.g., 1–3 h). Moreover, when using Cys pseudoprolines as peptide macrocyclization-enhancing moieties a considerable reduction in reaction time was observed compared to a peptide containing trityl protected Cys.