Hydroxy-PEG4-t-butyl acetate

This Hydroxy-PEG4-t-butyl acetate linker is designed for use in PROTAC assembly, providing a hydrophilic polyethylene glycol segment that can improve solubility and enable flexible spatial positioning between the target-binding ligand and the E3-recruiting module. Its protected hydroxyl functionality supports controlled conjugation strategies, while the acetate ester motif offers a practical handle for downstream functionalization. The detailed Structure and Reactivity parameters are provided below.

Structure: The linker contains a polyethylene glycol chain bearing a terminal hydroxyl group that is masked as a t-butyl acetate ester. It features ether linkages within the PEG backbone, an ester linkage to the acetate, and a tertiary-butyl group that confers acid-labile protection. Overall polarity is enhanced by the PEG segment.

Reactivity: The protected hydroxyl can be deprotected under mild acidic conditions to regenerate the free alcohol for subsequent coupling. Ester hydrolysis proceeds via nucleophilic acyl substitution, typically using aqueous or mixed solvents compatible with PEG. For PROTAC construction, the regenerated alcohol can be converted to activated derivatives (for example, via standard esterification or ether-forming coupling chemistries) under base and coupling reagent conditions, with catalysts chosen to preserve the PEG chain integrity.