Boc-Aminooxy-PEG4-CH2CO2H

This Boc-Aminooxy-PEG4-CH2CO2H linker is designed for modular PROTAC assembly, providing an orthogonally protected aminooxy handle for reliable conjugation to targeting ligands and a PEG-based spacer to support productive ternary complex formation. Its flexible, hydrophilic architecture can improve solubility and reduce steric constraints during targeted protein degradation workflows. The following sections describe the linker’s structure and the practical reactivity considerations used when constructing PROTACs with this scaffold.

Structure: The molecule combines a Boc-protected aminooxy functionality with a poly(ethylene glycol) spacer and a terminal carboxylic acid. It contains an aminooxy ether linkage, ether-rich PEG segments, and a carboxyl group capable of forming amide or activated ester derivatives. Overall, it is polar and conformationally flexible.

Reactivity: The Boc group enables controlled deprotection to reveal the aminooxy moiety, which can participate in oxime or related aminooxy coupling strategies under standard aqueous/organic conditions. The terminal carboxylic acid is suitable for formation of activated intermediates (for example, via common coupling reagent chemistries) to generate amide bonds with amine-bearing ligands. PEG flexibility supports efficient conjugation without disrupting PROTAC assembly principles.