mPEG6-CH2CH2COONHS ester

This mPEG6-CH2CH2COONHS ester is a polyethylene glycol–based activated ester designed for efficient conjugation in PROTAC workflows. Its NHS-activated carboxylate enables rapid amide bond formation with primary amines, supporting modular assembly of targeted protein degraders while improving solubility and handling of PROTAC components. The subsequent points describe the structure and practical reactivity considerations in detail.

Structure: The molecule contains an mPEG chain linked through an ethylene spacer to an NHS-activated carboxylate. It features an amide-forming activated ester functional group, ether linkages within the PEG segment, and a terminal N-hydroxysuccinimide leaving group. Overall, it is designed to enhance aqueous compatibility.

Reactivity: Suitable for coupling reactions that convert the NHS ester into a stable amide with primary amines under mild, aqueous or mixed-solvent conditions. The process proceeds via nucleophilic acyl substitution, where the amine attacks the activated carbonyl and the NHS group departs. Commonly used bases and buffering systems help maintain amine nucleophilicity while minimizing hydrolysis; reactions are typically performed promptly to limit water-driven deactivation.