This compound, methyl 2-((2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)ethyl)amino)acetate, is a protected building block used in solid-phase peptide synthesis (SPPS). It incorporates an Fmoc-protected ethylenediamine moiety linked to a glycine methyl ester, serving as a spacer or non-natural amino acid analog to introduce flexibility into peptide chains. The fluorenylmethoxycarbonyl (Fmoc) group protects the primary amine, allowing selective deprotection with mild bases like piperidine during stepwise peptide assembly without affecting other functionalities. This enables the construction of complex peptides, peptidomimetics, and modified proteins. It is essential in pharmaceutical development for bioactive peptides and in biochemical research to investigate molecular interactions and functions.