HO-PEG7-OH

This HO-PEG7-OH linker is a polyethylene glycol-based diol designed to serve as a flexible spacer in targeted protein degradation (PROTAC) constructs. Its ether-rich backbone enhances solubility and can improve effective reach and conformational freedom between the recruiting ligand and the target-binding moiety. The subsequent points describe its structural attributes and practical considerations for PROTAC assembly and subsequent conjugation chemistry.

Structure: HO-PEG7-OH is a PEG diol featuring repeating ethylene oxide units connected through ether linkages, capped with terminal hydroxyl groups. The molecule is flexible, polar, and capable of hydrogen bonding, with ether oxygen atoms providing strong solvation and reduced aggregation in typical organic–aqueous workups.

Reactivity: The terminal alcohols enable standard PROTAC linker functionalization via esterification or etherification, including conversion to activated carbonate/ester or mesylate/tosylate intermediates for subsequent nucleophilic substitution. Typical conjugation strategies use coupling reagents compatible with alcohol activation, with inert atmospheres when required, and solvents such as polar aprotic media or mixed organic–aqueous systems. Reaction pathways generally proceed through alcohol activation followed by nucleophilic attack to form stable ester or ether linkages.