Aminooxy-PEG-CH2CO2tBu is a compound used in pharmaceutical research and development. It is classified as an aminooxy-functionalized polyethylene glycol (PEG) derivative, containing a tert-butyl ester group at one end and an aminooxy group at the other end. The aminooxy group in Aminooxy-PEG-CH2CO2tBu is a versatile functional group that can be used for various bioconjugation reactions, including the formation of oxime bonds with aldehydes or ketones. This compound has been widely utilized in the development of protein and peptide therapeutics, drug delivery systems, and diagnostic imaging agents. The tert-butyl ester group at one end of the molecule provides protection for the aminooxy group during synthesis and can be easily removed by mild acidic hydrolysis. The introduction of functional groups like the aminooxy group in Aminooxy-PEG-CH2CO2tBu has greatly facilitated the development of novel pharmaceutical products with improved properties, such as enhanced stability, solubility, and specificity.