Boc-Aminooxy-PEG3-acid

Boc-Aminooxy-PEG3-acid is a PEG-based PROTAC linker building block designed to connect a hydroxylamine (aminooxy) handle to carboxylic-acid functional groups while providing conformational flexibility and improved solubility in common coupling media. Its aminooxy functionality supports oxime-formation strategies used in targeted protein degradation workflows, enabling robust conjugation between ligands and E3 ligands. The details below describe its structure and practical reactivity considerations for PROTAC synthesis.

Structure: The molecule contains a protected aminooxy group, a poly(ethylene glycol) spacer, and a terminal carboxylic acid. It features ether linkages within the PEG chain, an amide-containing Boc protecting group, and a carboxylic acid for subsequent coupling. These functionalities support hydrophilicity and modular attachment chemistry.

Reactivity: The aminooxy group is suited for oxime bond formation with aldehyde-bearing ligands under mildly acidic to neutral conditions, typically in the presence of water-compatible buffers. The carboxylic acid can be activated for amide coupling to complementary amines using standard carbodiimide or acid-activator approaches. Boc protection is generally removed prior to oxime or coupling steps, following established deprotection protocols.