Fmoc-L-glutamic acid 1-methyl ester, with CAS number 145038-49-9, is a protected derivative of the amino acid L-glutamic acid. It features an N-terminal 9-fluorenylmethoxycarbonyl (Fmoc) protecting group and a side-chain carboxylic acid protected as a methyl ester. This specific protection pattern makes it a crucial building block in solid-phase peptide synthesis (SPPS) using the Fmoc strategy. Its primary application is as a specialized monomer for the controlled incorporation of glutamic acid residues into synthetic peptides. The methyl ester protection on the side chain allows for selective deprotection under different conditions than the main chain, enabling the synthesis of peptides with free or further modified glutamic acid side chains. It is extensively used in research and development for producing peptide-based pharmaceuticals, diagnostic agents, and biochemical probes. This compound is a staple in peptide chemistry laboratories. Proper handling requires standard precautions for laboratory chemicals, including avoiding inhalation and contact with skin or eyes.