t-Boc-Aminooxy-PEG4-CH2CO2-t-Bu is a PEG derivative with a t-Boc protected aminooxy group and a t-Bu carboxylic acid group. The protected aminooxy can be deprotected under mild acidic conditions and then can be reacted with an aldehyde or ketone group to form a stable oxime linkage. The t-butyl protected carboxyl group can be deprotected under acidic conditions. The hydrophilic PEG linker increases the water solubility of the compound.
