Synthesis of carbon-11-labeled CK1 inhibitors as new potential PET radiotracers for imaging of Alzheimer's disease

Mingzhang Gao, Min Wang, Qi Huang Zheng

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The reference standards methyl 3-((2,2-difluoro-5H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-d]imidazol-6-yl)carbamoyl)benzoate (5a) and N-(2,2-difluoro-5H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-d]imidazol-6-yl)-3-methoxybenzamide (5c), and their corresponding desmethylated precursors 3-((2,2-difluoro-5H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-d]imidazol-6-yl)carbamoyl)benzoic acid (6a) and N-(2,2-difluoro-5H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-d]imidazol-6-yl)-3-hydroxybenzamide (6b), were synthesized from 5-amino-2,2-difluoro-1,3-benzodioxole and 3-substituted benzoic acids in 5 and 6 steps with 33% and 11%, 30% and 7% overall chemical yield, respectively. Carbon-11-labeled casein kinase 1 (CK1) inhibitors, [11C]methyl 3-((2,2-difluoro-5H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-d]imidazol-6-yl)carbamoyl)benzoate ([11C]5a) and N-(2,2-difluoro-5H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-d]imidazol-6-yl)-3-[11C]methoxybenzamide ([11C]5c), were prepared from their O-desmethylated precursor 6a or 6b with [11C]CH3OTf through O-[11C]methylation and isolated by HPLC combined with SPE in 40–45% radiochemical yield, based on [11C]CO2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the molar activity (MA) at EOB was 370–740 GBq/μmol with a total synthesis time of ∼40-min from EOB.

Original languageEnglish (US)
Pages (from-to)2234-2238
Number of pages5
JournalBioorganic and Medicinal Chemistry Letters
Volume28
Issue number13
DOIs
StatePublished - Jul 15 2018

Keywords

  • Alzheimer's disease (AD)
  • Carbon-11-labeled CK1 inhibitors
  • Casein kinase 1 (CK1)
  • Positron emission tomography (PET)
  • Radiosynthesis

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Pharmaceutical Science
  • Drug Discovery
  • Clinical Biochemistry
  • Organic Chemistry

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