N-(Azido-PEG3)-N-Boc-PEG4-acid is a PEG-based PROTAC linker with a terminal azide group and is used in the synthesis of PROTACs[1]
PROTACs contain two different ligands connected by a linker; one is a ligand for an E3 ubiquitin ligase and the other is for the target protein. PROTACs exploit the intracellular ubiquitin-proteasome system to selectively degrade target proteins.
[1]. Kanazaki K, et al. Feasibility of poly(ethylene glycol) derivatives as diagnostic drug carriers for tumor imaging. J Control Release. 2016 Mar 28;226:115-23.