N3-PEG4-tBu

Azido-PEG4-t-butyl ester is a click chemistry linker containing an azide (N3) and a t-butyl ester moiety. The hydrophilic PEG spacer increases solubility in aqueous media. The azide group is reactive toward alkyne, BCN, DBCO via Click Chemistry . The t-butyl protected carboxyl group can be deprotected under acidic conditions.