Amino-PEG3-t-butyl acetate

Amino-PEG3-t-butyl acetate is a PEG-based PROTAC linker building block designed to provide a flexible hydrophilic spacer while presenting a protected amino functionality for controlled conjugation. Its ether-rich backbone supports solubility and productive ternary-complex formation, and the t-butyl acetate moiety enables orthogonal handling during stepwise synthesis. The following sections describe the structure and practical reactivity considerations for incorporating this linker into targeted protein degradation constructs.

Structure: The linker contains a short poly(ethylene glycol) segment with an ether-rich backbone that confers conformational flexibility. An amino group is present as a functional handle, while a t-butyl acetate group provides an acid-labile protecting group. The molecule features ester and amine functionalities connected through stable C–N and C–O bonds.

Reactivity: This linker is typically used in PROTAC assembly via orthogonal protection/deprotection strategies and amide or carbamate-forming coupling from the amino handle. The t-butyl acetate group is compatible with conditions that preserve ester integrity, then can be removed under acid-promoted conditions to reveal the reactive amine. Common coupling approaches employ activated carboxylic acids or activated esters, using amide/carbamate chemistry in polar aprotic solvents with base to drive nucleophilic substitution.