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The chloro-phosphonium coupling reagent PyCloP was developed as an alternative to the BOP reagent, avoiding the release of the toxic HMPA in the activation step.

CAS: 133894-48-1

Synonym: Chlorotripyrrolidinophosphonium hexafluorophosphate




Molecular Formula

C12H24ClN3P · PF6

Molecular Weight

421.73 [gr/mol]


White to off-white crystalline powder

Storage Conditions

Store in a cool and dry place (2-8oC)


  • PyCloP often gives better results than other phosphonium-HOBt reagents, for the coupling of N-methylated amino acids.
  • PyCloP, 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.


  • Coupling N-Methylated Amino Acids Using PyBroP and PyCloP Halogenophosphonium Salts: Mechanism and Fields of Application
    J. Coste, E. Frerot, P. Jouin J. Org. Chem., 1994, 59 (9), pp 2437–2446.

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