mPEG-t-Butyl Ester

mPEG-t-butyl ester is a protected intermediate subclass widely employed in multi-step bioconjugation and organic synthesis, where the tert-butyl ester group ensures reaction orthogonality by preventing unwanted side reactions. Representative structures such as mPEG₁₁-OCH₂CH₂COOtBu combine tunable PEG spacer lengths with acid-labile protection, enabling tailored solubility and controlled deprotection under mild acidic conditions—though their utility inherently requires an additional processing step to reveal the active carboxyl functionality.