Used as a protected amino acid derivative in peptide synthesis, enabling selective coupling reactions without side-chain interference. The tert-butoxycarbonyl (Boc) group provides reversible amine protection under mild acidic conditions, while the methyl ester masks the carboxylic acid for later hydrolysis or activation. Commonly employed in solid-phase and solution-phase peptide assembly, it supports the stepwise construction of complex peptides with high purity and yield. Also utilized in the synthesis of pharmaceutical intermediates and bioactive molecules where controlled functional group reactivity is essential.