Fmoc-N-amido-PEG7-acid

This Fmoc-N-amido-PEG7-acid linker is designed to support PROTAC assembly by providing a protected amide functionality and a flexible polyethylene glycol spacer that can improve effective reach and reduce steric constraints between the target-binding and E3-ligase-binding modules. Its Fmoc group enables orthogonal stepwise synthesis, while the carboxylic acid handle supports reliable conjugation strategies. The following sections describe its structure-related features and practical reactivity considerations for constructing PROTACs in a research setting.

Structure: The linker contains an Fmoc-protected amide linked to a PEG-based polyether chain terminated by a carboxylic acid. It features aromatic carbamate protection, amide and ester-like connectivity within the PEG framework, and multiple ether oxygen atoms that confer flexibility and hydrophilicity.

Reactivity: The carboxylic acid can be activated for coupling to amine-bearing ligands using standard peptide-coupling chemistries, enabling formation of stable amide bonds under mild conditions. The Fmoc protecting group is typically removed with base to reveal the nucleophilic amine for subsequent stepwise conjugation. Solvent systems commonly used for PROTAC linker synthesis include polar aprotic media, and coupling reactions may employ activating agents and bases compatible with Fmoc deprotection and amide formation.