t-Boc-Aminooxy-PEG4-azide

t-Boc-Aminooxy-PEG4-azide is a PEG-based bifunctional linker designed for PROTAC construction, enabling efficient conjugation between an aminooxy-containing handle and azide-reactive partners. Its polyethylene glycol segment provides hydrophilicity and conformational flexibility, which can help accommodate varied warhead geometries and improve practical coupling efficiency. The t-Boc protecting group supports controlled stepwise synthesis, while the azide functionality enables orthogonal “click” style attachment in targeted protein degradation workflows.

Structure: The linker contains a PEG chain that imparts water-compatible, flexible spacing, flanked by an aminooxy functionality and an azide group. It features carbamate-protected aminooxy chemistry and ether linkages typical of PEG backbones, with stable covalent C–O and N–N/N–N–C connectivity appropriate for bioconjugation.

Reactivity: The t-Boc group is typically removed under mild acid conditions to expose the aminooxy for subsequent oxime or related condensation chemistry with carbonyl-bearing ligands. The azide enables copper(I)-catalyzed azide–alkyne cycloaddition or strain-promoted azide–alkene/alkyne coupling, depending on partner functionality. Standard PROTAC linker assembly commonly employs polar aprotic solvents and inert atmosphere where required to preserve sensitive intermediates and maintain coupling efficiency.