Synthesis and Radiolabeling of a polar [125 I]I-1,2,4,5-Tetrazine

Natasha Bidesi, Vladimir Shalgunov, Umberto Maria Battisti, Lars Hvass, Jesper Tranekjaer Jørgensen, Christian B M Poulie, Andreas I Jensen, Andreas Kjaer, Matthias M Herth*

*Corresponding author for this work


Pretargeting imaging has gained a lot of prominence, due to its excellent bioorthogonality and improved imaging contrast compared to conventional imaging. A new iodo tetrazine (Tz) derivative has been synthesized and further developed into the corresponding iodine-125 (125 I) analog (12), via the trimethylstannane precursor. Radiolabeling with either N-chlorosuccinimide or chloramine-T, in either MeCN or MeOH proceeded with a radiochemical conversion (RCC) of >80%. Subsequent deprotection only proved successful, among the tested conditions, when the radiolabeled Tz was stirred in 6-M HCl(aq.) at 60°C for 2.5 h. To the best of our knowledge, this is the first H-tetrazine labeled with iodine. In vivo investigations on the pretargeting ability of 12 are currently under way.

Original languageEnglish
JournalJournal of Labelled Compounds and Radiopharmaceuticals
Issue number1
Pages (from-to)22-30
Number of pages9
Publication statusPublished - Jan 2023


  • Cell Line, Tumor
  • Click Chemistry/methods
  • Heterocyclic Compounds
  • Iodine Radioisotopes
  • Radiopharmaceuticals
  • idodine-125
  • pretargeting
  • click chemistry
  • bioorthogonal
  • tetrazine


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