Hydroxy-PEG13-Boc

Hydroxy-PEG13-Boc is a polyethylene glycol-based linker that provides a defined spacer length and terminal hydroxyl group for modular conjugation workflows. The tert-butyl ester-protected carboxyl functionality enables stepwise assembly of conjugates under standard organic synthesis conditions. Its PEG character helps tune hydrophilicity and conformational presentation, which can improve practical handling and downstream coupling strategies. The following sections describe its structure and the reactivity considerations relevant to PROTAC construction.

Structure: The linker comprises a hydrophilic PEG chain terminated by a hydroxyl group and a tert-butyl ester-protected carboxyl handle. It contains repeating ether linkages, a tert-butyl ester-protected carboxyl group, and a terminal alcohol. These features confer strong hydrogen-bonding capacity and favorable aqueous compatibility.

Reactivity: The tert-butyl ester can be cleaved using acid-mediated conditions to reveal the carboxylic acid when that handle is needed during PROTAC synthesis. The terminal hydroxyl supports formation of activated derivatives or coupling partners, commonly via standard functional-group interconversion routes. For assembly, the hydroxyl group can be functionalized independently, while the carboxylic acid can be revealed by controlled ester deprotection and activated for subsequent coupling. Solvent choice and temperature are selected to maintain linker stability and minimize side reactions.