t-Boc-Aminooxy-PEG-t-butyl ester is a compound commonly used in pharmaceutical research and development. It belongs to the class of aminooxy functionalized polyethylene glycol (PEG) reagents, which contain both PEG and aminooxy functional groups. The aminooxy functional group is a versatile tool in medicinal chemistry that can be used for conjugation, crosslinking, and labeling of various biomolecules. The t-Boc protecting group on the aminooxy group can be easily removed under mild conditions, allowing for efficient functionalization of the PEG polymer. The resulting PEG conjugates possess improved solubility, stability, and pharmacokinetic properties, which makes them useful for drug delivery applications.