The fluorenylmethoxycarbonyl protecting group (Fmoc) is a base-labile amine protecting group used in organic synthesis, particularly in peptide synthesis. It is popular for its stability toward acids and hydrolysis and its selective removal by weak bases, such as piperidine, without affecting most other protecting groups or sensitive functional groups. Fmoc protection is especially advantageous in solid-phase peptide synthesis (SPPS), where its compatibility with other reagents and ease of removal streamline synthesis workflows. Upon deprotection, Fmoc yields a byproduct (Dibenzofulvene) that can be monitored by UV spectroscopy, allowing for efficient reaction tracking.