Boc-D-Tyr(OtBu)-Aib-Gln(Trt)-Gly-OH is a protected tetrapeptide utilized in peptide synthesis. The Boc (tert-Butoxycarbonyl) group safeguards the N-terminus of the D-tyrosine (D-Tyr) residue, while the OtBu (tert-butyl) group protects the hydroxyl group on the D-tyrosine's side chain, preventing premature reactions during synthesis. The second residue, Aib (α-aminoisobutyric acid), is known for its ability to induce helical conformations in peptides. The Gln (Glutamine) residue has its side chain protected by a Trt (Trityl) group, allowing for selective deprotection later in the synthesis process. The final residue, Gly (Glycine), has a free carboxyl group at the C-terminus, denoted by -OH, which can be used for further coupling or modifications. This peptide is specifically designed to incorporate D-tyrosine, Aib, glutamine, and glycine into peptide structures, with carefully selected protective groups to ensure controlled and efficient synthesis.