t-Boc-aminooxy-PEG3-amine

t-Boc-aminooxy-PEG3-amine is a PEG-based bifunctional linker designed for constructing PROTACs and related targeted protein degradation conjugates. Its protected aminooxy functionality enables controlled installation of oxime-bearing handles, while the PEG spacer provides hydrophilicity and conformational flexibility that can improve solubility and linker tolerance in degrader architectures. The subsequent points describe its structural features and practical considerations for PROTAC synthesis and coupling strategies.

Structure: The molecule contains a tert-butoxycarbonyl-protected aminooxy group and a terminal primary amine separated by a short polyethylene glycol chain. It features an aminooxy linkage and multiple ether units, providing a flexible, hydrogen-bonding-rich scaffold with enhanced aqueous compatibility.

Reactivity: The Boc-protected aminooxy group is typically unmasked under standard acid deprotection conditions to reveal the reactive aminooxy functionality. The resulting aminooxy can form oxime linkages with aldehyde-bearing partners under mild, aqueous-compatible conditions. The terminal amine can be used for amide coupling or other nucleophilic acyl substitutions, enabling modular assembly of PROTAC components; common coupling reagents and bases are selected to preserve oxime integrity during synthesis.