m-PEG2-O-Ph-NH2

This m-PEG2-O-Ph-NH2 linker is a polyethylene glycol-based, aniline-terminated building block designed to connect targeting ligands in PROTAC architectures. Its ether-rich PEG segment supports aqueous compatibility and conformational flexibility, while the terminal aniline enables robust conjugation strategies to assemble degraders. The balanced polarity and linker dynamics can help maintain productive ternary complex formation. Detailed structural and reactivity considerations are provided below for researchers planning PROTAC synthesis and optimization.

Structure: The linker contains a short PEG chain bearing an ether linkage and a para-substituted phenyl core connected through an oxygen atom. A terminal primary aniline provides a nucleophilic aromatic amine. Overall, the structure combines flexible polyether segments with aromatic rigidity, supporting solubility and adaptable spatial presentation.

Reactivity: The primary aniline is suited for amide bond formation via activated carboxylic acids or acid chlorides, and for urea/carbamate-type linkages using appropriate coupling reagents. Typical PROTAC assembly uses standard peptide-coupling conditions with bases and polar aprotic solvents, followed by purification to remove coupling byproducts. The PEG ether segment is generally stable under mild coupling conditions, enabling reliable stepwise conjugation to targeting ligands.