Aminooxy-PEG3-bromide

Aminooxy-PEG3-bromide is a PEG-based bifunctional linker designed to connect PROTAC ligands through oxime-forming chemistry, enabling efficient assembly of targeted protein degradation constructs. Its ether-rich, flexible scaffold helps tune linker length and conformational freedom, which can improve productive ternary complex formation. The bromide handle supports controlled functionalization for downstream conjugation. The following points describe the molecule’s structure and practical reactivity considerations in PROTAC synthesis.

Structure: The linker comprises a short poly(ethylene glycol) chain terminated by an aminooxy group and a bromide leaving group. It contains ether linkages that confer flexibility and water compatibility, alongside an aminooxy functional group capable of forming oxime linkages. The bromide provides a site for substitution chemistry.

Reactivity: Aminooxy-PEG3-bromide is commonly used in PROTAC linker construction via nucleophilic substitution at the bromide to install a desired partner, followed by oxime ligation with an aldehyde-bearing moiety. Oxime formation typically proceeds under mildly acidic aqueous or mixed solvent conditions, favoring condensation while minimizing side reactions. Solvents such as alcohols or aqueous buffers are often employed, with careful control of pH and aldehyde concentration to drive selective oxime generation.