Methylamino-PEG3-acid

Methylamino-PEG3-acid is a polyethylene glycol-based PROTAC linker building block designed to provide aqueous solubility, conformational flexibility, and a chemically addressable functional handle for controlled conjugation. Its ether-rich backbone helps position warheads for efficient ternary complex formation, while the terminal acid enables robust coupling strategies commonly used in targeted protein degradation workflows. The following sections describe the linker’s structure and practical reactivity considerations in detail below.

Structure: The linker comprises a short PEG segment featuring repeating ether linkages, terminating in a carboxylic acid and bearing a methylamino substituent. It contains flexible C–O and C–C connectivity, with a polar, hydrogen-bonding-rich environment that supports water compatibility and stable amide/ester-forming chemistry.

Reactivity: The terminal carboxylic acid is suitable for activation toward amide-bond formation with amine-bearing ligands, typically using standard carboxyl-activation reagents under mild base/neutral conditions. Alternatively, it can be coupled via acid chloride or activated ester intermediates to promote efficient conjugation. The methylamino group can participate in selective functionalization depending on protection strategy. Common solvents include polar aprotic media, with reaction progress monitored by chromatographic methods.