Thiol-PEG4-alcohol

This Thiol-PEG4-alcohol linker is designed for modular PROTAC assembly, providing a PEG-based spacer that improves solubility and supports efficient conjugation to targeting ligands and E3-recruiting moieties. Its terminal thiol functionality enables controlled coupling strategies, while the alcohol handle supports versatile downstream derivatization. These features make it a practical building block for constructing well-defined targeted protein degraders; detailed structural and reactivity considerations are provided below.

Structure: The linker comprises a polyethylene glycol chain terminated by an alcohol and a thiol group, connected through ether and carbon–heteroatom linkages. Its flexible, hydrophilic PEG backbone promotes aqueous compatibility, while the thiol provides a reactive sulfur center for chemoselective conjugation.

Reactivity: The thiol can participate in thiol–maleimide or thiol–disulfide exchange–type coupling, enabling formation of stable thioether or disulfide-linked intermediates under mild, reducing-compatible conditions. Typical workflows employ aqueous or mixed aqueous/organic solvents buffered to maintain thiol integrity, with careful control of oxidation state; catalysts are generally unnecessary for standard thiol addition reactions.