Benzyl-PEG4-alcohol

Benzyl-PEG4-alcohol is a polyethylene glycol-based linker building block designed to provide a flexible, hydrophilic spacer for PROTAC architectures. Its ether-rich backbone can improve solubility and enable productive spatial positioning between a ligand warhead and an E3-recruiting moiety. The benzyl end group offers a chemically addressable handle for further functionalization, supporting robust linker assembly strategies. Detailed structural and reactivity considerations are provided below.

Structure: The molecule comprises an oligo(ethylene glycol) chain terminating in a primary alcohol, with a benzyl substituent at the other end. It features multiple ether linkages along the PEG backbone and a benzylic carbon–carbon bond, yielding a flexible, polar scaffold with hydrogen-bonding capability from the terminal hydroxyl group.

Reactivity: The terminal alcohol enables common PROTAC linker derivatization via activation to form esters or carbamates, or via substitution to introduce electrophiles compatible with ligand conjugation. Typical approaches use alcohol-activation reagents and base in polar organic solvents, followed by nucleophilic coupling under mild conditions. The PEG ether chain is generally stable under standard coupling chemistries, supporting stepwise synthesis of bifunctional degraders.