Synthesis and evaluation of a series of 1,2,4,5-tetrazines for bioorthogonal conjugation

Bioconjug Chem. 2011 Nov 16;22(11):2263-70. doi: 10.1021/bc200295y. Epub 2011 Oct 24.


1,2,4,5-Tetrazines have been established as effective dienes for inverse electron demand [4 + 2] Diels-Alder cycloaddition reactions with strained alkenes for over 50 years. Recently, this reaction pair combination has been applied to bioorthogonal labeling and cell detection applications; however, to date, there has been no detailed examination and optimization of tetrazines for use in biological experiments. Here, we report the synthesis and characterization of 12 conjugatable tetrazines. The tetrazines were all synthesized in a similar fashion and were screened in parallel to identify candidates most ideally suited for biological studies. In depth follow-up studies revealed compounds with varying degrees of stability and reactivity that could each be useful in different bioorthogonal applications. One promising, highly stable, and water-soluble derivative was used in pretargeted cancer cell labeling studies, confirming its utility as a bioorthogonal moiety.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Alkenes / chemistry
  • Cell Line, Tumor / cytology
  • Cell Line, Tumor / metabolism
  • Click Chemistry / methods*
  • Humans
  • Molecular Structure
  • Norbornanes / chemistry
  • Organic Chemicals / chemical synthesis*
  • Organic Chemicals / chemistry*
  • Staining and Labeling / methods


  • Alkenes
  • Norbornanes
  • Organic Chemicals