Bromo-PEG4-MS

Bromo-PEG4-MS is a PEG-based bromo-functional linker designed for efficient conjugation in PROTAC workflows, enabling reliable spatial separation between the target-binding ligand and the E3 ligase-recruiting moiety. Its ether-rich polyethylene glycol scaffold supports favorable solubility and conformational flexibility, which can improve productive ternary complex formation. The bromo handle provides a chemically addressable site for linker installation, and the following sections describe its structure and practical reactivity considerations in detail below.

Structure: The linker comprises a polyethylene glycol chain bearing a terminal bromo substituent, with multiple ether linkages that confer flexibility and hydrophilicity. The carbon–bromine bond serves as the primary functional handle, while the ether oxygens provide hydrogen-bonding capacity and influence overall polarity and solvation behavior.

Reactivity: The terminal bromo group is suitable for nucleophilic substitution-based coupling, commonly using amines or other nucleophiles under standard organic synthesis conditions. Reaction design typically relies on halide displacement principles, with solvent choice and base selection tuned to promote substitution while minimizing side reactions such as elimination. For PROTAC assembly, the linker is generally functionalized to install the appropriate attachment chemistry to the ligands, followed by purification-compatible handling to preserve reactivity.