PyAOP is a phosphonium salt derived from HOAt, is generally more efficient than BOP and PyBOP as coupling reagent.

CAS: 156311-83-0

Synonym: (7-Azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate




Molecular Formula


Molecular Weight

521.38 [gr/mol]


White to off white crystalline powder

Storage Conditions

Store in a cool and dry place


  • This pyrrolidino derivative PyAOP does not release the toxic HMPA in the activation step.
  • PyAOP, as other phosphonium salts, cannot react with free amine function and therefore does not terminate the peptide growing as the aminium salts do, through the formation of guanidine derivatives.
  • It is special advantageous for cyclization reactions.


  • On the Use of PyAOP, a Phosphonium Salt Derived from HOAt, in Solid-Phase Peptide Synthesis
    F. Albericio, M. Cases, J. Alsina, S. A. Triolo, L. A. Carpino, and S. A. Kates. Tetrahedron Lett., 1997, 38, 4853-4856.
  • Advantageous Applications of Azabenzotriazole (Triazo1opyridine)-based Coupling Reagents to Solid-phase Peptide Synthesis
    L. A. Carpino,  A. El-Faham, C. A. Minorb, and F. Albericio J. Chem. Soc., Chem. Commun., 1994, 201-203.

Request an Information or Quotation