Fmoc-N-Amido-PEG2-alcohol

Fmoc-N-Amido-PEG2-alcohol, provides a PEG-based spacer bearing an Fmoc-protected amide motif and a terminal alcohol handle. Its flexible, hydrophilic architecture is well suited for connecting targeting ligands to E3-recruiting warheads while supporting solubility and minimizing steric interference. The subsequent points describe the structural features and practical synthetic considerations for assembling PROTAC constructs.

Structure: The linker contains an Fmoc-protected nitrogen within an amide linkage, coupled to a short polyethylene glycol segment terminating in a primary alcohol. It features aromatic carbamate-derived functionality, amide and ether bonds, and a flexible PEG chain that enhances hydrophilicity and conformational adaptability.

Reactivity: The terminal alcohol enables conversion to PROTAC-ready coupling partners via standard alcohol activation and subsequent nucleophilic substitution or acylation. The Fmoc group can be removed under base-promoted conditions to reveal a reactive amine for amide-bond formation. Typical PROTAC linker assembly strategies use orthogonal protection, mild coupling reagents, and polar aprotic solvents to maintain PEG integrity and suppress side reactions.