m-PEG2-O-Ph-3-NH2

This m-PEG2-O-Ph-3-NH2 linker is a polyethylene glycol–based, aniline-functionalized aromatic linker designed to connect targeting ligands in PROTAC architectures. Its ether-rich PEG segment provides conformational flexibility and improved solubility, while the meta-substituted phenyl core offers a defined attachment scaffold for controlled conjugation. The terminal amine enables straightforward coupling to activated carboxyl or electrophilic groups, supporting modular synthesis of targeted protein degraders. Detailed structural and reactivity considerations are provided below.

Structure: The linker combines a PEG chain with an ether linkage and a meta-disubstituted phenyl ring bearing a terminal primary amine. Its structure contains ether oxygen atoms and aromatic C–C bonds, with a flexible hydrophilic PEG segment that supports favorable solvation and linker dynamics in conjugates.

Reactivity: The primary amine is suitable for amide-bond formation via coupling to activated carboxylic acid derivatives (for example, acid chlorides or activated esters) under standard peptide-coupling conditions. Typical approaches use base and coupling reagents in polar aprotic solvents, proceeding through nucleophilic acyl substitution. For PROTAC assembly, the linker can be introduced as an amine handle to generate stable, non-labile conjugates compatible with subsequent purification and characterization.