Skip to main content


TOTU is a coupling reagent belong to a family of OxymaPure® based coupling reagents.

The use of TOTU is possible both in classical peptide synthesis and in solid-phase peptide synthesis.

CAS: 136849-72-4

Synonym: O-[(Ethoxycarbonyl)cyanomethylenamino]-N,N,N′,N′-tetramethyluronium tetrafluoroborate




Molecular Formula


Molecular Weight

328.10 [gr/mol]


White to off-white crystalline powder

Storage Conditions

Protect from the light and store in a cool and dry place (≤25oC)


  • TOTU was developed as peptide coupling reagent by researchers at Hoechst AG in the early 1990s, as an alternative to benzotriazole derivatives.
  • TOTU distinguished by its high activation potential, straightforward preparation (one-pot reaction) and high solubility. The only solvents used in the preparation are toluene and acetone. In addition, the sodium salt of the oxime employed in the reaction can be obtained directly from ethyl cyanoacetate.
  • TOTU, HOTU, and COMU® are obtained as the O-form isomer (uronium salts), which is more reactive than the typical hydroxybenzotriazole N-form (aminium salts).
  • The by-products resulting from the activation of a carboxyl group with TOTU are tetramethylurea and ethyl 2-hydroxyimino-2-cyanoacetate, which can readily be extracted in the water.
  • Moreover, the anion of the oxime is yellow in color and can therefore be readily detected on extraction of the reaction mixture with, for example, bicarbonate. The use of TOTU is possible both in classical peptide synthesis and in solid-phase peptide synthesis.


  • Azidopeptide nucleic acid. An alternative strategy for solid-phase peptide nucleic acid (PNA) synthesis)
    F, Debaene and N. Winssinger Org. Lett., 2003, Vol. 5, No. 23, 4445-4447.
    Read Article
  • Oxyma: an efficient additive for peptide synthesis to replace the benzotriazole-based HOBt and HOAt with a lower risk of explosion
    R. Subirós-Funosas, R. Prohens, R. Barbas, A. El-Faham, and F. Albericio Chemistry, 2009, 15(37), 9394-403.
    Read Article
  • Thermal Stability Assessment of Peptide Coupling Reagents Commonly Used in Pharmaceutical Manufacturing
    Jeffrey B. Sperry*, Christopher J. Minteer, JingYa Tao, Rebecca Johnson, Remzi Duzguner, Michael Hawksworth, Samantha Oke, Paul F. Richardson, Richard Barnhart, David R. Bill, Robert A. Giusto, and John D. Weaver III
    Org. Process Res. Dev. 2018, 22, 9, 1262–1275


TOTU Stable and Efficient Coupling Reagent


View Poster

Request an Information or Quotation

Information Request

    Price Quote Request

      Skip to content