m-PEG5-Boc

m-PEG5-Boc is a polyethylene glycol based PROTAC linker building block designed to provide aqueous compatibility, conformational flexibility, and tunable spacing between targeting and recruiting modules. Its Boc-protected functionality enables controlled synthetic elaboration, supporting modular assembly of degraders where linker length and polarity influence productive ternary complex formation. The following sections describe the structure and the practical reactivity considerations for constructing PROTACs using this linker.

Structure: This linker combines a PEG chain with a Boc-protected functional group, featuring ether linkages along the polyethylene glycol backbone and a carbamate motif from the Boc group. The resulting material is typically hydrophilic and conformationally flexible, with chemical stability under standard organic synthesis conditions.

Reactivity: Boc-protected intermediates are commonly used in stepwise PROTAC synthesis, where deprotection is performed under acid-mediated conditions to reveal a reactive amine for subsequent coupling. The freed amine can then participate in amide or carbamate-forming reactions with activated carboxylic acid derivatives. Mild bases and appropriate coupling reagents are generally selected to preserve the PEG ether chain and maintain linker integrity.