Propargyl-PEG1-NH2

Propargyl-PEG1-NH2 is a PEG-based bifunctional linker designed for modular PROTAC assembly, combining a terminal alkyne handle with a primary amine for controlled conjugation to ligands. Its ether-rich, flexible PEG segment helps tune linker solubility and conformational behavior, supporting efficient formation of productive ternary complexes. The molecule is described in detail below, including its structural features and practical reactivity considerations for targeted protein degradation workflows.

Structure: The linker contains a polyethylene glycol segment with repeating ether units, providing conformational flexibility and enhanced hydrophilicity. A terminal propargyl group introduces a carbon–carbon triple bond suitable for click-type coupling, while a primary amine enables nucleophilic functionalization. Overall, it presents ether and amine functionalities with stable covalent linkages.

Reactivity: The terminal alkyne is compatible with azide–alkyne cycloaddition strategies commonly used in PROTAC synthesis, enabling efficient conjugation under copper-catalyzed or copper-free conditions depending on ligand sensitivity. The primary amine can participate in amide bond formation via activated carboxylic acids (e.g., using standard coupling reagents) or in reductive amination workflows. Typical reactions are performed in polar organic solvents or suitable aqueous-organic mixtures, with base selection guided by protecting-group compatibility and amine reactivity.