Azido-PEG3-acid

This Azido-PEG3-acid linker is designed for modular PROTAC synthesis, providing a flexible polyethylene glycol spacer terminated with an azide handle and a carboxylic acid for conjugation. Its ether-rich chain supports favorable solubility and conformational adaptability, while the azide enables bioorthogonal “click” coupling to complementary alkynes. These features facilitate efficient assembly of targeted protein degraders, and the following points describe its structure and practical use in PROTAC workflows in detail.

Structure: The linker contains a PEG-based polyether backbone featuring repeating ether linkages that confer flexibility and hydrophilicity. A terminal azide group provides a stable azide functional handle, while a terminal carboxylic acid enables acid-mediated coupling. Overall, it is an amphiphilic, polar small-molecule scaffold suitable for conjugation chemistry.

Reactivity: The azide moiety is commonly used in copper-catalyzed azide–alkyne cycloaddition or strain-promoted azide–alkyne cycloaddition, enabling selective formation of a triazole linkage under mild, bioorthogonal conditions. The carboxylic acid can be activated for amide or ester bond formation using standard coupling reagents and bases, typically in polar aprotic solvents. Reaction design should account for PEG solvation and preserve azide integrity during activation and coupling steps.