Aminooxy-PEG4-azide

Aminooxy-PEG4-azide is a bifunctional PROTAC linker designed to connect a primary amine or carbonyl-derived handle to an azide-bearing partner for modular assembly. Its PEG-based spacer provides conformational flexibility and improved solubility, which can help maintain productive ternary complex formation in targeted protein degradation workflows. The molecule’s reactive aminooxy group enables chemoselective oxime formation, while the azide handle supports bioorthogonal conjugation strategies.

Structure: The linker contains an aminooxy functionality paired with a PEG ether chain terminating in an azide group. Ether linkages in the PEG segment confer flexibility and hydrophilicity, while the azide provides a stable, orthogonal functional handle. The aminooxy group is primed for condensation with carbonyls to form oxime linkages.

Reactivity: For PROTAC construction, the aminooxy group typically reacts with aldehydes or ketones under mild, aqueous-compatible conditions to generate oxime bonds via chemoselective condensation. The terminal azide is commonly used in copper-free or copper-assisted azide–alkyne cycloaddition, depending on the desired labeling environment and compatibility with sensitive ligands. Solvent systems are often selected to balance oxime formation and click efficiency, with reaction pH and temperature tuned to maintain ligand integrity.