Benzyl-PEG4-Boc is widely used in organic synthesis and pharmaceutical research as a versatile protecting group and linker. Its primary application is in peptide synthesis, where the Boc (tert-butyloxycarbonyl) group protects amines during the reaction process, ensuring selective coupling and preventing unwanted side reactions. The PEG4 (polyethylene glycol) spacer enhances solubility and flexibility, making it valuable in bioconjugation and drug delivery systems. It is also employed in the development of prodrugs and targeted therapies, where the benzyl group can be modified or cleaved to release active compounds. Additionally, it serves as a building block in the creation of complex molecules, enabling controlled release and improved pharmacokinetics in drug design.