Fmoc-D-Gln(Trt)-OH is primarily used in solid-phase peptide synthesis (SPPS) as a building block for constructing peptides. The Fmoc (fluorenylmethyloxycarbonyl) group acts as a protective group for the amino group, ensuring selective deprotection during the synthesis process. The Trt (trityl) group protects the side chain of glutamine, preventing unwanted reactions. This compound is particularly valuable in synthesizing complex peptides with specific sequences, especially in pharmaceutical research and development. Its application extends to the production of therapeutic peptides, peptide hormones, and other biologically active molecules, where precise control over amino acid incorporation is critical.