m-PEG3-aminooxy-Boc

This m-PEG3-aminooxy-Boc linker is designed for incorporation into PROTAC architectures where controlled, hydrophilic spacing and chemoselective conjugation are advantageous. The aminooxy functionality enables formation of stable oxime linkages with carbonyl-bearing partners, while the Boc-protected amine supports orthogonal synthetic handling. Together, these features facilitate modular assembly of targeted protein degraders; the following sections describe the structure and reactivity considerations in detail.

Structure: The linker contains a PEG-based ether chain providing water-compatible flexibility, terminated by an aminooxy group suitable for oxime chemistry. A Boc-protected amine offers a stable, masked nucleophile under standard conditions, with carbamate-type bonding that can be selectively unmasked during synthesis.

Reactivity: Aminooxy groups typically react with aldehydes or ketones to form oxime linkages under mild, acid-catalyzed conditions, often using compatible aqueous/organic solvent mixtures. Boc deprotection is commonly achieved with acid (for example, trifluoroacetic acid in suitable solvents) to reveal the amine for subsequent coupling steps. For PROTAC construction, the linker is best used in sequential, orthogonal steps to preserve oxime-forming capability and maintain functional-group compatibility.