N-(Azido-PEG3)-N-Boc-PEG3-acid

This N-(Azido-PEG3)-N-Boc-PEG3-acid linker is designed for modular PROTAC assembly, providing a chemically addressable azide handle for bioorthogonal conjugation and a protected carboxyl functionality for controlled coupling. Its PEG-rich, flexible architecture supports productive ternary complex formation and improves solubility and linker dynamics in targeted protein degradation workflows. Detailed structural and reactivity considerations for constructing PROTACs are provided below.

Structure: The linker contains an azide-bearing PEG segment and a Boc-protected amine, together with a terminal carboxylic acid. It features ether-rich PEG chains, an azide functional group, and carbamate protection, enabling orthogonal functionalization. The overall structure is flexible, polar, and well-suited for aqueous PROTAC chemistry.

Reactivity: The azide group is compatible with copper-free or copper-catalyzed azide–alkyne cycloaddition strategies commonly used to connect PROTAC fragments under mild conditions. The Boc group can be removed with standard acid-mediated deprotection to reveal an amine for subsequent amide or carbamate-forming couplings. The carboxylic acid enables activation (for example, via common coupling reagents) to form stable amide bonds with targeting ligands, typically in polar aprotic solvents with controlled pH.