endo-BCN-PEG3-NH-Boc

endo-BCN-PEG3-NH-Boc, is designed to connect a bioorthogonal BCN (bicyclononyne) handle to a PEG-based spacer while providing a protected amine for controlled functionalization. Its combination of a strain-promoted cycloaddition motif and a flexible hydrophilic tether supports efficient conjugation strategies and can improve solubility and linker accessibility in targeted protein degradation workflows. The

Structure: The linker incorporates an endo-oriented bicyclononyne core for strain-promoted reactivity, coupled to a polyethylene glycol spacer that imparts flexibility and hydrophilicity. An amide-adjacent protected amine (Boc) enables orthogonal downstream derivatization. Multiple carbon–carbon and carbon–nitrogen bonds define a stable, non-labile scaffold suitable for bioconjugation.

Reactivity: BCN-based PROTAC assembly typically relies on strain-promoted azide–alkyne cycloaddition principles, proceeding without external catalysts under mild conditions. For Boc-handling steps, deprotection is commonly performed using acid-mediated conditions to reveal a free amine for subsequent coupling. Conjugation reactions are generally conducted in compatible aqueous or mixed solvent systems, with base or coupling reagents selected according to the intended amide/urea formation chemistry.