m-PEG9-azide

m-PEG9-azide is a polyethylene glycol (PEG) based azide-functionalized linker designed for modular assembly of PROTACs via bioorthogonal “click” chemistry. Its flexible, hydrophilic PEG architecture can improve solubility and facilitate productive spatial presentation of ligands, supporting efficient ternary complex formation. The azide handle enables reliable conjugation to complementary alkyne-bearing partners, and the resulting PROTAC linkages are commonly evaluated for targeted protein degradation; detailed structural and synthetic considerations are provided below.

Structure: The linker consists of a PEG chain terminated with an azide group, providing a flexible, ether-rich backbone with polar oxygen atoms. The azide functionality serves as a reactive handle for cycloaddition, while the ether linkages confer conformational mobility and favorable aqueous compatibility.

Reactivity: The azide group is suited for copper-catalyzed azide–alkyne cycloaddition or strain-promoted azide–alkyne cycloaddition, depending on the alkyne partner and experimental constraints. For copper-catalyzed routes, typical conditions employ a soluble Cu(I) source, an appropriate ligand to control copper speciation, and an aqueous or mixed solvent system compatible with sensitive ligands. The reaction proceeds via formation of a triazole linkage, enabling robust, chemoselective PROTAC assembly under mild conditions.