17-(Fmoc-amino)-5-oxo-6-aza-3,9,12,15-tetraoxaheptadecanoic Acid

This linker is designed for assembling PROTAC architectures by providing a chemically stable, hydrophilic spacer that can connect an E3 ligase-binding ligand to a target-binding ligand. Its ether-rich scaffold and protected amino functionality support modular conjugation strategies, helping researchers tune linker length, solubility, and functional-group compatibility for efficient targeted protein degradation workflows. The detailed structural and synthetic considerations are provided below.

Structure: The molecule contains a lactam-like carboxylic acid motif alongside multiple ether linkages that confer pronounced polarity and conformational flexibility. An Fmoc-protected amino group enables controlled amide formation without premature side reactions. Overall, it features stable C–O ether bonds, an acid functionality, and aromatic Fmoc chemistry.

Reactivity: For PROTAC construction, the carboxylic acid can be activated for amide coupling to a ligand bearing an appropriate amine, typically using standard coupling chemistries such as carbodiimide-based activation in compatible polar solvents. The Fmoc group supports orthogonal protection during synthesis and can be removed under base-promoted conditions to reveal the free amine for subsequent conjugation. Reaction design should account for maintaining ether stability and minimizing competing hydrolysis.