Facile synthesis of SSR180575 and discovery of 7-chloro-N,N,5-trimethyl-4-oxo-3(6-[18F]fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide, a potent pyridazinoindole ligand for PET imaging of TSPO in cancer

Yiu Yin Cheung, Michael L. Nickels, Dewei Tang, Jason R. Buck, H. Charles Manning

Research output: Contribution to journalArticle

12 Scopus citations


A novel synthesis of the translocator protein (TSPO) ligand 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide (SSR180575, 3) was achieved in four steps from commercially available starting materials. Focused structure-activity relationship development about the pyridazinoindole ring at the N3 position led to the discovery of 7-chloro-N,N,5-trimethyl-4-oxo-3(6-fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide (14), a novel ligand of comparable affinity. Radiolabeling with fluorine-18 (18F) yielded 7-chloro-N,N,5-trimethyl-4-oxo-3(6-[18F]fluoropyridin-2-yl)-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide ([18F]-14) in high radiochemical yield and specific activity. In vivo studies of [18F]-14 revealed this agent as a promising probe for molecular imaging of glioma.

Original languageEnglish
Pages (from-to)4466-4471
Number of pages6
JournalBioorganic and Medicinal Chemistry Letters
Issue number18
StatePublished - Sep 15 2014
Externally publishedYes


  • Fluorine-18
  • Glioma
  • PET
  • SSR180575
  • TSPO

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