N-(Biotin)-N-bis(PEG1-alcohol)

N-(Biotin)-N-bis(PEG1-alcohol), is designed to provide a biotin handle alongside flexible, hydrophilic PEG-based spacers that support effective conjugation and improved solubility in aqueous systems. Its structural features help maintain productive geometry between targeting and E3-recruiting elements, which is central to targeted protein degradation workflows. Detailed structural and reactivity considerations are provided below to guide experimental assembly of PROTAC constructs.

Structure: The linker incorporates a biotin-derived amide motif connected to an N-substituted center bearing two short PEG alcohol substituents. It contains amide and ether linkages, with terminal hydroxyl groups that enable hydrogen bonding and aqueous compatibility. Overall, it is a flexible, polar scaffold suitable for bioconjugation-oriented PROTAC designs.

Reactivity: The biotin-associated amide linkage supports standard bioconjugation strategies, while the terminal PEG alcohol groups enable derivatization via hydroxyl-reactive coupling chemistries commonly used in PROTAC synthesis. Typical approaches include formation of activated carbonate/ester intermediates or other alcohol-derivatization routes under mild base or coupling conditions, using polar aprotic solvents. Reaction planning should account for maintaining linker solubility and minimizing hydrolysis of activated intermediates.