Boc-Tyr(OtBu)-Aib-Gln(Trt)-OH is a protected tripeptide used in peptide synthesis. The Boc (tert-Butoxycarbonyl) group protects the N-terminus of the tyrosine (Tyr) residue, preventing it from reacting during synthesis. The hydroxyl group of tyrosine and the side chain amide group of glutamine (Gln) are protected by OtBu (tert-butyl) and Trt (Trityl) groups, respectively, which shield these functional groups from unwanted reactions until selective deprotection is performed. Aib (α-aminoisobutyric acid), known for its helical-inducing properties, is the middle residue in the sequence. The -OH at the C-terminus indicates a free carboxyl group, allowing for further coupling or modifications. This compound is used to incorporate tyrosine, Aib, and glutamine into peptides, with specific protections to ensure controlled and efficient peptide synthesis.