mPEG3-amine

This mPEG3-amine linker is a polyethylene glycol–based amine building block designed for constructing PROTAC conjugates where improved solubility, biocompatible interfaces, and controlled linker presentation are advantageous. Its terminal primary amine enables straightforward coupling to electrophilic warheads or activated handles, supporting modular assembly of targeted protein degraders. The following sections describe the linker’s structure and practical reactivity considerations in PROTAC synthesis.

Structure: mPEG3-amine is a methoxy-terminated PEG chain bearing a terminal primary amine. The polymer backbone consists of repeating ether linkages, providing a flexible, hydrophilic scaffold. The terminal amine offers a basic, nucleophilic functional group suitable for amide or urea formation under coupling conditions.

Reactivity: The primary amine can participate in nucleophilic acyl substitution to form amide bonds with activated carboxylic acids (such as acid chlorides, activated esters, or carboxylic acids under coupling reagents). Typical approaches use amide-coupling catalysts and base in polar organic solvents, proceeding via formation of an activated intermediate followed by amine attack. For PROTAC assembly, select orthogonal functional groups to preserve sensitive handles and minimize PEG chain degradation.