Bromoacetamido-PEG4-t-butyl ester is a PEG linker containing a bromide group and a t-butyl protected carboxyl group. The hydrophilic PEG spacer increases solubility in aqueous media. The bromide (Br) is a very good leaving group for nucleophilic substitution reactions. The t-butyl protected carboxyl group can be deprotected under acidic conditions.
Bromoacetamido-PEG4-C2-Boc is a PEG- and Alkyl/ether-based PROTAC linker can be used in the synthesis of PROTACs[1].
[1] Darren H. Wakefield, et al. Poly(vinyl ester) Polymers for In Vivo Nucleic Acid Delivery. US20130121954A1.