Amino-PEG5-acetic acid

Amino-PEG5-acetic acid, is a polyethylene glycol-based bifunctional building block designed to connect ligands in targeted protein degradation (PROTAC) constructs. Its PEG-rich scaffold provides conformational flexibility and aqueous compatibility, supporting productive ternary-complex formation. The amino and carboxylic acid functionalities enable straightforward conjugation to diverse warheads, facilitating modular PROTAC synthesis. Detailed structural and reactivity considerations are provided below.

Structure: The molecule contains a PEG chain bearing terminal amino and acetic acid groups, providing a flexible, hydrophilic backbone. It features ether linkages within the PEG segment, along with an amine and a carboxylic acid for functional-group interconversion. These features support water solubility and stable covalent attachment to PROTAC partners.

Reactivity: The amino group can be used for amide-bond formation with activated carboxylic acids, or for coupling to carboxylate-bearing ligands via common peptide-coupling chemistries. The carboxylic acid can be activated using standard coupling reagents to react with amines under mild base/solvent conditions. Typical approaches rely on nucleophilic acyl substitution facilitated by carbodiimide or uronium-type activators, with solvents such as DMF or DMSO and controlled pH to preserve linker integrity.