t-Boc-N-amido-PEG4-bromide

This t-Boc-N-amido-PEG4-bromide linker is designed for modular assembly of PROTACs by providing a PEG-based spacer that can improve solubility, conformational flexibility, and effective reach between the target-binding ligand and the E3-recruiting moiety. Its bromide handle enables controlled functionalization, while the protected amide functionality supports downstream coupling strategies. The following points describe the structure and practical reactivity considerations for constructing PROTAC architectures in a research setting.

Structure: The linker contains a poly(ethylene glycol) chain terminating in a bromide leaving group and an N-amido motif protected as a tert-butoxycarbonyl (t-Boc) derivative. It features ether linkages within the PEG segment, an amide bond, and a carbon–bromine bond at the terminus, contributing to polarity and solvation.

Reactivity: The bromide terminus is suitable for nucleophilic substitution with amines or other nucleophiles under conditions that favor alkylation, enabling attachment to ligand fragments bearing nucleophilic sites. The t-Boc group can be removed using standard acidolysis to reveal an amine for subsequent amide-forming couplings. Typical workflows employ dry polar aprotic solvents, inert atmosphere where appropriate, and coupling reagents compatible with amide bond formation.