NH2-PEG5-C6-Cl

This PEG-based linker is designed to support PROTAC assembly by providing a flexible, water-compatible spacer between an E3 ligase ligand and a target-binding moiety. Its ether-rich polyethylene glycol character can help tune effective distance and conformational freedom, which are key determinants of ternary complex formation and targeted protein degradation performance. The sections below describe the linker’s structure and practical reactivity considerations for constructing PROTACs in research settings.

Structure: The linker contains a terminal primary amine attached to a PEG chain, incorporating ether linkages that impart hydrophilicity and conformational flexibility. A chlorinated phenyl substituent contributes an aromatic scaffold suitable for downstream derivatization, while the overall structure supports stable, non-ionic spacer behavior under aqueous conditions.

Reactivity: The primary amine enables common PROTAC coupling strategies such as amide-bond formation with activated carboxylic acid derivatives, or nucleophilic substitution with suitably functionalized electrophiles. Practical synthesis typically employs standard peptide-coupling or amide-forming reagents under controlled pH, using polar aprotic solvents compatible with PEG stability. Reaction design should consider chemoselectivity to preserve the aromatic chloride for orthogonal functionalization when required.