Bis-PEG15-acid

Bis-PEG15-acid, is a polyethylene glycol-based bifunctional acid designed to connect two ligating fragments while providing conformational flexibility and improved aqueous compatibility. Its PEG-rich architecture can help maintain productive geometry for ternary complex formation and reduce non-specific interactions. The molecule is intended for researchers constructing targeted protein degradation (PROTAC) conjugates, and the following points describe its structure and practical reactivity considerations in PROTAC synthesis.

Structure: Bis-PEG15-acid is a PEG-based bis-functional linker featuring ether-rich polymer segments and terminal carboxylic acid functionality. The structure contains multiple C–O and C–C connections within the PEG backbone, offering high polarity and water solubility, with an acid group suitable for coupling chemistry.

Reactivity: The carboxylic acid termini enable standard PROTAC linker coupling to amine- or alcohol-containing warheads via amide or ester-forming activation. Typical approaches include converting the acid to an activated ester or using carbodiimide-mediated coupling under mild, aqueous or mixed-solvent conditions, often with base and coupling reagents. PEG linkers generally tolerate common organic solvents and do not require specialized catalysts beyond those used for amide/ester bond formation.