L-Phenylalanine benzyl ester hydrochloride is primarily used in peptide synthesis as a building block. It serves as a protected form of L-phenylalanine, where the benzyl ester group safeguards the carboxyl group during the synthesis process. This compound is particularly valuable in solid-phase peptide synthesis (SPPS) and solution-phase peptide synthesis, enabling the creation of complex peptides and proteins. Additionally, it is employed in the preparation of peptide-based pharmaceuticals and bioactive compounds, contributing to advancements in drug development and therapeutic research. Its stability and compatibility with various coupling reagents make it a reliable choice in organic and medicinal chemistry applications.