Azido-PEG1-CH2COOH

This Azido-PEG1-CH2COOH linker is designed for modular PROTAC synthesis, providing an azide handle for bioorthogonal conjugation and a terminal carboxylic acid for controlled attachment to targeting and E3 ligase-binding motifs. Its polyethylene glycol segment improves aqueous compatibility and can help tune linker flexibility and effective intramolecular reach in degradation constructs. The details below describe its structure and practical reactivity considerations for assembling PROTACs.

Structure: The molecule contains an azide functional group, a short polyethylene glycol segment, and a terminal carboxylic acid. It features ether linkages within the PEG chain, an aliphatic methylene spacer, and typical carbonyl and ionic carboxylate chemistry, supporting water-compatible, polar behavior.

Reactivity: The azide group is suitable for strain-promoted or copper-catalyzed azide–alkyne cycloaddition to connect PROTAC fragments under mild, orthogonal conditions. The carboxylic acid can be activated for amide-bond formation using standard coupling chemistries, enabling attachment to primary amines on ligands. Typical approaches employ dry organic solvents or buffered media compatible with azide stability, with careful control of pH and exclusion of strong nucleophiles that could interfere with functional groups.