t-Boc-N-amido-PEG9-amine

t-Boc-N-amido-PEG9-amine is a PEG-based, amide-containing linker building block designed to support the synthesis of PROTACs by providing a flexible hydrophilic spacer and a protected primary amine handle for controlled coupling chemistry. Its combination of ether-rich chain mobility and amide connectivity helps maintain productive ternary-complex formation characteristics while improving solubility and handling during iterative assembly. The following sections describe the linker’s structural features and practical reactivity considerations in PROTAC construction.

Structure: The linker comprises an ether-rich polyethylene glycol segment connected through an amide motif, terminating in a primary amine that is masked as a tert-butoxycarbonyl (t-Boc) carbamate. It features stable C–N and C–O bonds, with a flexible, conformationally mobile backbone that enhances aqueous compatibility.

Reactivity: The t-Boc group is typically removed under mild acid conditions to reveal the free amine for subsequent PROTAC coupling. Suitable reactions include amide bond formation with activated carboxylic acids (or acid derivatives) and carbamate/urea-forming routes using appropriate electrophiles. Commonly used solvents are polar aprotic media for coupling steps, while deprotection is performed in acid-compatible solvents; reaction design should preserve the integrity of other functional groups and minimize side reactions.