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@INPROCEEDINGS{Kolks:865320,
      author       = {Kolks, N. and Zlatopolskiy, BD and Urusova, EA and
                      Neumaier, B.},
      title        = {{S}ynthesis of {N}-methyl- and
                      5-{HO}-[18{F}]fluorotryptophans},
      reportid     = {FZJ-2019-04822},
      year         = {2019},
      abstract     = {Ziel/Aim:Tryptophan (Trp) metabolism is altered in numerous
                      pathological processes. 7-[F-18]FTrp developed in our group
                      is a promising PET-tracer for imaging of Trp metabolism but
                      is unable to distinguish between the two pathways of Trp
                      metabolization. The aim of this project was the development
                      of procedures for the preparation of NinMe-6- and
                      5-HO-7-[F-18]FTrp as PET-probes suitable for selective
                      visualization of the kynurenine or serotonin
                      pathway.Methodik/Methods:Precursor for the radiosynthesis of
                      NinMe-6-[F-18]FTrp, (S,S)-BPB-Ni-NinMe-6-Bpin-Trp, was
                      synthesized starting from 6-bromoindole. Miyaura borylation,
                      followed by a Mannich reaction and quaternization with MeI
                      furnished
                      N,N,N-(6-Bpin-NinMe-indolyl)methyltrimethylammonium iodide.
                      Alkylation of (S)-BPB-Ni-Gly with the latter and
                      Nin-methylation afforded the desired precursor.
                      Boc-7-Bpin-5-AcO-Trp-OtBu was prepared via Ir-catalyzed
                      2,7-diborylation of Boc-5-AcO-Trp-OtBu, accessible from
                      5-OH-Trp in three reaction steps, followed by selective
                      2-deborylation using Bi(OAc)3. Both precursors were
                      radiolabeled according to the protocol of alcohol-enhanced
                      Cu-mediated F-18-fluorination. The decomposition of the
                      labeled precursors under acidic conditions afforded the
                      F-18-labeled amino acids NinMe-6- and
                      5-HO-7-[F-18]FTrp.Ergebnisse/Results:(S,S)-BPB-Ni-NinMe-6-Bpin-Trp
                      was obtained in a total yield of $13\%$ after 5 steps and
                      Boc-7-BPin-5-AcO-Trp-OtBu in a $12\%$ yield after 5 steps.
                      (S,S)-BPB-Ni-NinMe-6-[F-18]FTrp was produced in RCCs of up
                      to $90\%,$ decomposed to Nin-Me-6-[F-18]FTrp and isolated by
                      HPLC in RCY of 10 – $15\%.$ Boc-5-OAc-7-Bpin-Trp-OtBu was
                      labeled with an RCC of $25\%$ and after deprotection
                      5-HO-7-[F-18]FTrp was obtained similarly to
                      NinMe-6-[F-18]FTrp but in lower
                      RCY.Schlussfolgerungen/Conclusions:Nin-Me-6- and
                      5-HO-7-[F-18]FTrp represent promising PET-probes for the
                      delineation of kynurenine and serotonin pathways of Trp
                      metabolism. Both probes were successfully prepared using
                      alcohol-enhanced Cu-mediated radiofluorination.},
      month         = {Apr},
      date          = {2019-04-03},
      organization  = {57. Jahrestagung der Deutschen
                       Gesellschaft für Nuklearmedizin,
                       Bremen (Germany), 3 Apr 2019 - 6 Apr
                       2019},
      subtyp        = {After Call},
      cin          = {INM-5},
      cid          = {I:(DE-Juel1)INM-5-20090406},
      pnm          = {573 - Neuroimaging (POF3-573)},
      pid          = {G:(DE-HGF)POF3-573},
      typ          = {PUB:(DE-HGF)6},
      doi          = {10.1055/s-0039-1683491},
      url          = {https://juser.fz-juelich.de/record/865320},
}