DEPBT | CAS 165534-43-0 | ≥98%

DEPBT — 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one — is a phosphate-type peptide coupling reagent valued for low-racemisation amide bond formation. On activation it forms a 3-hydroxy-1,2,3-benzotriazin-4(3H)-one-derived active ester in situ, delivering the low-epimerisation behaviour of the benzotriazinone leaving group from a single crystalline reagent. It is particularly suited to couplings where epimerisation at the activated residue is the principal risk. DEPBT is supplied as a white to almost-white crystalline solid, soluble in common peptide-coupling solvents such as THF and DMF.

Common Scientific Applications

• Amide and peptide bond formation: a tertiary amine base generates the carboxylate of the N-protected acid, which attacks the phosphorus centre of DEPBT; the intermediate rearranges to a benzotriazinone-derived active ester, which the amine then aminolyses to give the amide.
• Low-racemisation segment coupling: the benzotriazinone-derived active ester preserves configuration at the activated C-terminal residue, making DEPBT well suited to fragment or segment condensation, where racemisation is otherwise severe.
• Racemisation-prone residues: couples readily epimerised substrates such as arylglycines and phenylglycine derivatives with high retention of configuration.
• Reduced side-chain protection: DEPBT couplings often avoid the need to protect the side-chain hydroxy groups of tyrosine, serine and threonine, or the imidazole of histidine.
• Cyclic peptides and macrolactamisation: mediates head-to-tail cyclisation of linear peptides and the synthesis of cyclic peptides such as cyclopenta- and cycloheptapeptides.
• Solution- and solid-phase synthesis: applied in both solution and solid-phase peptide synthesis, including the assembly of complex, racemisation-sensitive peptides and natural products.

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.