Boc-Aminooxy-PEG5-amine

t-Boc-Aminooxy-PEG5-amine compound contains a Boc-protected aminooxy group and an amino group. The amino group is reactive with carboxylic acids, activated NHS esters. The protected aminooxy can be deprotected under mild acidic conditions and then can react with an aldehyde or ketone group to form a stable oxime linkage. The hydrophilic PEG spacer increases solubility in aqueous media.