三乙二醇单对甲苯磺酸酯，2-(2-(2-Hydroxyethoxy)ethoxy)ethyl 4-methylbenzenesulfonate [Tos-PEG3]；98%

是基于 PEG 的 PROTAC linker，可用于 PROTAC 的合成。Tos-PEG3 (结构 1) 可用于合成 3'-氨基氧基寡核苷酸固体载体。
PEG3-Tos is a PEG derivative containing a hydroxyl group and a tosyl group. The hydrophilic PEG spacer increases solubility in aqueous media. The hydroxyl group enables further derivatization or replacement with other reactive functional groups. The tosyl group is a very good leaving group for nucleophilic substitution reactions.