EEDQ | CAS 16357-59-8 | ≥95%

EEDQ — N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline — is a dihydroquinoline condensing reagent for amide and peptide bond formation. It activates a carboxylic acid as a mixed ethyl carbonic anhydride in situ, in the presence of the amine partner and without added tertiary amine base. EEDQ is supplied as an off-white to white crystalline solid, soluble in common organic solvents and aqueous-organic mixtures but insoluble in water.

Common Scientific Applications

• Direct amide and peptide coupling: EEDQ reacts with the carboxylic acid to form a mixed ethyl carbonic anhydride in situ; the amine attacks this intermediate as it forms, giving the amide with quinoline, ethanol and carbon dioxide as by-products.
• One-step, low-racemisation coupling: couples acylamino acids with amino acid esters in a single step with suppression of racemisation under standard solution-phase conditions.
• DNA-compatible amide coupling: reported in on-DNA amide-coupling studies for DNA-encoded library synthesis, with substrate-dependent performance.
• Polysaccharide and materials modification: employed in the regioselective quaternisation of chitosan and amphiphilic chitosan derivatives, and in the preparation of amide-modified QCM sensor surfaces.
• Carboxyl-group-selective protein modification: used in biochemical studies to covalently modify accessible protein carboxylates, including enzyme active-site studies such as F1-ATPase labelling.

Further Reading

For guidance on selecting between carbodiimides, aminium/uronium salts, phosphonium salts and other reagent classes for amide and peptide bond formation, see NorrChemica's Lab Journal guide: Choosing a Coupling Reagent for Amide and Peptide Bond Formation.